Genito-urinary Flashcards

Question

You are the interventional radiology fellow in your hospital. A nephrologist has asked you for an opinion on four patients they feel require renal arterial intervention. Patient A is a 68-year-old male who has had a catheter angiogram which showed a 60% narrowing in the right renal artery. This patient has refractory hypertension. Patient B is a 42-year-old female, also with refractory hypertension. She has had an MR angiogram, which has shown several stenoses, with intervening mild aneurysm formation, in the proximal right renal artery. Patient C is a 72-year-old female with impaired renal function, who underwent captopril renal scintigraphy. On the baseline study, there was a similar appearance of the kidneys. On the captopril study, there was a differential split of renal function of 15% between the right and left kidney, with a decrease of time to peak activity of 320 seconds. The final patient D had a renal Doppler ultrasound, which showed a biphasic flow pattern in the segmental arteries, with a slow upstroke. Which of these patients has significant atherosclerotic renal artery stenosis? [B1 Q29] A. Patients A and B. B. Patients C and D. C. Patients A, C, and D. D. Patients B, C, and D. E. All of them.

Answer 1

**Patients C and D** A 70% stenosis is taken as the cut-off for signiﬁcant stenosis. Patient B is atypical in their age. They also have imaging characteristics typical of ﬁbromuscular dysplasia. Patients C and D have classical imaging features of renal artery stenosis (RAS). Regarding ultrasound diagnosis using Doppler, this is made by either showing ﬂow acceleration immediately distal to the site of stenosis or showing dampened ﬂow in the segmental arteries. In the renal artery, a peak systolic velocity of over 180 cm/s combined with a renal/aortic velocity ratio of over 3 is reported as being the most sensitive method of detecting RAS.

Answer 2

**Arterial phase CT abdomen**. The IVU has surprisingly been helpful in showing a delayed increasing nephrogram, a classical, although uncommon, appearance of renal vein thrombosis. This is also indicated by the history of glomerulonephritis, which can manifest as nephrotic syndrome, the most common cause for renal vein thrombosis. Ultrasound is often successful at identifying a thrombosed right renal vein but is not useful in assessing the longer left renal vein. Gradient and SE sequences are both helpful in assessing the renal venous system, with GE giving low-signal thrombus and SE giving high-signal thrombus. Arterial phase CT would be too early to show a venous ﬁlling defect and thus may not contribute, although it may show a rim nephrogram. Portal venous phase CT is reasonably sensitive at detecting the lack of enhancement within the renal vein and abnormal enhancement pattern within the affected kidney.

Answer 3

**MRI** MRI is superior to the other imaging modalities listed at ruling out renal vein invasion. CT is still very accurate (reported as high as 96%), but MR has the advantage of being able to accurately differentiate benign from malignant thrombus. MR offers no advantage in detecting nodal disease, however, and patients being considered for curative surgery should undergo staging CT of the chest, abdomen and pelvis. PET does not have a specific role for detecting renal vein invasion.

Answer 4

**Refer for immediate venous intervention**. There are several complications to be aware of in the immediate post-transplant period. The most efﬁcient and cost-effective method of surveillance for these is ultrasound. Acute rejection and acute tubular necrosis (ATN) both occur early in the post-transplant phase and can be difﬁcult to differentiate. Both can cause elevation of pulsatility index (PI) (normal <1.5) and resistive index (RI) (normal <0.7), although these tend to be higher with rejection. ATN is more common with cadaveric transplants. It usually resolves within a matter of days or weeks, but ultimately biopsy can be necessary to reliably differentiate these processes. This patient probably had a degree of ATN initially. Arterial occlusion is uncommon and is evident by reduced/absent arterial ﬂow in the main artery as well as in the interlobar arteries, which can demonstrate loss of ﬂow with any cause of severe oedema (e.g. renal vein thrombosis or acute rejection). Renal vein thrombosis causes pain and anuria. It is associated with early treatment with cyclosporine and steroids. It also causes a rise in the RI and PI. The key feature to notice is the persistent ﬂow in the main renal artery, reducing the likelihood of renal arterial thrombosis. There is also a tubular structure noted in the hilum, which is what a thrombosed renal vein looks like, and reversal of diastolic ﬂow on arterial traces.

Answer 5

**PI < 1.5, RI < 0.7, prominence of renal pyramids**. PI < 1.5 or RI < 0.7 can be regarded as normal, whilst a PI > 1.8 or RI = 0.9 should be regarded as abnormal. Although both ATN and acute rejection cause the PI and RI to rise, the likelihood of acute rejection is greater with higher values. Complete absence of diastolic ﬂow, or ﬂow reversal, is due to acute rejection in most of the case. Morphologically, the transplant kidney is very similar to the native and many of the subtle differences are attributed to the improved resolution of the former. There is a well-deﬁned renal parenchyma peripherally, with a highly reﬂective echogenic sinus centrally. In distinction to the native kidney, the renal pyramids are more commonly visualized within the transplant, being hypoechoic, relative to the parenchyma itself. Loss of cortico-medullary differentiation is pathological and is a B mode ﬁnding that can be associated with acute rejection.

Answer 6

**Renal Vein Thrombosis** **Immediate faint persistent nephrogram** RVT Acute glomerulonephritis Chronic severe ischaemia

Answer 7

**Acute complete arterial occlusion** **Rim nephrogram** Acute complete arterial occlusion Severe hydronephrosis **Striated nephrogram** Acute ureteric obstruction Acute pyelonephritis Acute renal vein thrombosis AR polycystic kidney Medullary sponge kindey

Answer 8

**Produces moth-eaten nephrograms after thrombosis of the microaneurysms** **PAN** Affects **medium and small** arteries. **Multiple microaneurysms 2-3 cm in size**, which when **thrombosed** produce **moth-eaten nephrogram**. Angiography has high sensitivity and specificity but a much higher negative than positive predictive value in diagnosis. Diagnosis is often made with clinical features and angiography.

Answer 9

**Fibromuscular dysplasia** FMD accounts for 35% of RAS. It is more common in children and young adults, affecting **females > males**. It is associated with hypertension and progressive renal insufficiency. FMD occurs bilaterally in 2 ⁄ 3 of cases and R > L 4:1. It usually affects the **mid distal renal artery**, and there can be a **beaded appearance of artery.**

Answer 10

**Perinuclear anti-neutrophil cytoplasmic - pANCA** While several forms of arteritis can cause multiple small renal aneurysms, it is **polyarteritis nodosa** that does so most commonly, affecting men more than women with a mean age of 55 years, the range being 18–81 years. It is associated with HIV and hepatitis B infection, and **pANCA** is usually positive. Systemic lupus erythematosus: **anti-double-stranded DNA antibodies** Goodpasture’s disease: **anti-basement membrane antibodies** Sjogren’s syndrome: **anti-Ro and anti-La antibodies** rheumatoid arthritis: **anti-immunoglobulin G (anti-IgG), also known as rheumatoid factor**

Answer 11

**Polyarteritis nodosa** Appearances are virtually diagnostic of polyarteritis nodosa. The condition is characterised by focal areas of necrotising arteritis with fibrinoid necrosis and small aneurysm formation in skin, kidneys, cardiovascular system, and central nervous system

Answer 12

Acute glomerulonephritis, **RVT** and chronic severe ischaemia are all causes of immediate faint persistent nephrogram.

Answer 13

**Repeat CT in 3–6 months**. Solid masses smaller than 1 cm are challenging. Firstly, there is a reasonable **chance that a very small solid mass is benign**. Secondly, it is often **difﬁcult to characterize a mass smaller than 1 cm as solid and enhancing**, despite a meticulous technique using state-of-the-art CT and MR imaging. Thirdly, these masses are often **too small to biopsy**, therefore when encountering a mass that is believed to be solid and is less than 1 cm in size, it is reasonable to observe them with an initial examination with CT or MR at 3–6 months followed by yearly examinations. A full work-up could ensue when the mass reaches 1 cm in size.

Answer 14

**Ablation zone unchanged in size over time**. Following ablation, the treatment zone is larger than the original lesion, as a margin of normal tissue is intentionally ablated to prevent recurrence. This should reduce in size/involute over time. If the ablation zone remains the same or increases in size, recurrence should be suspected. Lack of enhancement is a reliable indicator of successful treatment. It is not uncommon to ﬁnd peripheral enhancement in the immediate post-treatment period due to reactive hyperaemia. Any nodular or central enhancement indicates incomplete treatment or recurrence.

Answer 15

**Haemorrhage is the most common major complication** **Post-RFA syndrome (Flu-like symptoms)** occurs **24-48 hours post-ablation**. It is a likely inflammatory response to tumour necrosis or cytokine production. Persistence of fever beyond day 10 should be evaluated for infection. **Haemorrhage is most seen in central tumours**. Ureteral strictures and urinomas are rare.

Answer 16

**Tumour size > 2.5 cm** Stage T2 disease is indicated when the tumour size is greater than 2.5cm.

Answer 17

**Renal Vein Invasion** In TCC inferior vena cava and renal vein invasion are uncommon

Answer 18

**Renal Cell Carcinoma** A single portal venous phase CT is not the optimum image set to characterize renal parenchymal lesions. However, renal cell carcinoma is more commonly encountered than high-density cysts. Furthermore, carcinoma is most frequently found in men (2:1) aged over 50 years. Kidney neoplasms tend to have densities **above 30 HU on an unenhanced CT** and rise by more than 10–20 HU post-contrast, usually being **above 70 HU in the portal phase**

Answer 19

**T3c N0 M0** **T1 <7 cm** - Limited to kidney **T2 >7cm** - Limited to kidney **T3 tumour extends beyond the kidney**, into either the adrenal gland or perinephric tissues (T3a), the **renal vein or vena cava** below the diaphragm (T3b) or the vena cava above the diaphragm, or it invades the wall of the vena cava (T3c). **T4 tumour invades beyond Gerota’s fascia**. N1 or N2 nodal disease refers to involvement of a single regional node, or more than one regional node, respectively. Overall, T3c N0 M0 disease represents stage III disease

Answer 20

**Successful** The practice of radiofrequency ablation of renal tumours is emerging. Currently, CT 1 month after the procedure is used to assess treatment success. If enhancing prior to ablation, the tumour is regarded as ablated if there is <10 HU rise in attenuation following contrast administration. Bulky persistent irregular peripheral enhancement is the commonest appearance of an incompletely treated lesion

Answer 21

**T1W post-gadolinium with pre-contrast T1W signal subtracted** The **cornerstone of diagnosis here is the post-contrast enhancement of renal cell carcinoma. To identify this among the high T1 signal of haemorrhage or protein within cysts, it is ideal to subtract the precontrast T1 signal**. Fat suppression will not remove the distracting high signal from mildly complicated cysts. Risk of renal cell carcinoma is increased in adult polycystic renal disease when in renal failure. Hence, caution may be required since at certain levels of renal impairment the use of MRI contrast is not advised.

Answer 22

**Calcification** **No calcification in AML** whereas it is seen in 10% of renal cell carcinomas. Both these tumours can be hyper vascular. The cornerstone of diagnosis of an angiomyolipoma is identifying fat on CT or MRI; however, fat has been reported in renal cell carcinoma, and peripheral or renal sinus fat can become trapped in any large renal tumour

Answer 23

**Renal mass in keeping with renal cell carcinoma and hepatosplenomegaly without focal hepatic or splenic lesions**. Stauffer described a syndrome of nephrogenic hepatopathy in which a renal cancer without liver metastases causes hepatosplenomegaly and abnormal liver function. Renal cell carcinoma paraneoplastic phenomena include erythrocytosis and hypercalcaemia

Answer 24

**Renal oncocytoma**. This is a benign renal cell neoplasm responsible for about 5% of all adult primary renal epithelial neoplasms. It typically occurs in elderly men. They usually appear as **solitary, well- demarcated**, unencapsulated, fairly **homogeneous** renal **cortical** tumours with **central stellate scar**. **Bilateral, multicentric oncocytomas** are seen in hereditary syndromes of renal oncocytosis and **Birt–Hogg–Dubé syndrome**. A central stellate scar is seen in approximately one-third. However, distinguishing them from RCC on imaging is not reliable. Leiomyoma of the kidney is a benign smooth muscle neoplasm. It appears as a well- circumscribed, homogeneous, exophytic solid mass that shows uniform enhancement on contrast-enhanced CT. It may occasionally be cystic. Metanephric adenoma is a benign renal neoplasm that is more common in middle-aged to elderly females. It is associated with polycythaemia in 10%. It typically appears as a well- deﬁned, unencapsulated, solitary mass that may be hyperattenuating on unenhanced CT. Calciﬁcation can be seen in up to 20%. Hemangioma of the kidney occurs as an unencapsulated, solitary lesion that frequently arises from the renal pyramids or the pelvis. Contrast-enhanced CT or MRI may show early intense enhancement, with persistent enhancement on delayed images. Juxtaglomerular cell (JGC) neoplasm or reninoma is an extremely rare, benign renal neoplasm of myoendocrine cell origin, which is associated with a clinical triad of hypertension, hypokalaemia, and high plasma renin activity. It typically appears as a unilateral, well- circumscribed, cortical tumour and often measures less than 3 cm, but otherwise is indistinguishable from other cortical neoplasms.

Answer 25

**Oncocytoma** **Benign**. Oncocytoma is a tubular adenoma that is very rarely malignant. They are often asymptomatic even when large. The **central scar** is typical and is **due to haemorrhage and infarction of the tumour having outgrown its vascular supply**. Radiological differentiation from renal cell carcinoma can be very difficult and percutaneous needle **biopsy is unreliable**. **Nephrectomy is therefore often indicated**

Answer 26

**Multifocality bilateralism and metachronous tumours occur together in 4-6%** Co-existent RCC in 10% of cases. Due to diffuse bilateral renal involvement patients with oncocytosis often present with abnormal renal function. Final diagnosis is by biopsy

Answer 27

**Wilms tumour**. Sporadic aniridia is associated with nephron-blastomatosis (multiple nephrogenic rests) and an increased risk of Wilms tumour. At CT, the nephrogenic rests appear as homogenous, hypodense nodules/peripheral rind, with little or no enhancement compared to the compressed normal cortical tissue. Any new, enlarging, or heterogenous mass in the setting of nephron-blastomatosis indicates the development of a Wilms tumour.

Answer 28

**Nephroblastoma** Also called Wilms’ tumour, this lesion typically presents as a large mass, crossing the midline and commonly displacing the large vessels (in contrast to neuroblastoma, where the mass encases the vessels). This is the most common neoplasm in children between 1 and 8 years of age.

Answer 29

**Renal calculi are present in most patients** SCC of the kidney is a relatively rare condition. It carries a **poor prognosis** due to its **aggressive nature**. Both **renal calculi and chronic infection** have been implicated in its aetiology. Cross sectional imaging appearances are identical to those of TCC

Answer 30

**Mesoblastic nephroma** This is a **hamartoma** and is the **most common solid neoplasm in neonates**. It typically **involves the renal sinus** and there is no invasion of the veins (differentiating it from Wilms’ tumour) or the collecting system. **small areas of necrosis**

Answer 31

**The presence of aneurysmal blood vessels within the lesion**. Both well-differentiated retroperitoneal liposarcomas and exophytic renal angiomyolipomas can be very large in size and thus size is not a discriminating factor. Both contain large amounts of mature lipid, thus signiﬁcant portions of the lesion will have negative Hounsﬁeld attenuation values on CT imaging. Aneurysmal blood vessels are commonly seen in large angiomyolipomas, whereas well differentiated liposarcomas are generally rather hypo-vascular lesions. Both angiomyolipomas and retroperitoneal liposarcomas may contain areas of soft tissue density. Liposarcoma is probably more likely to have an irregular margin and may contain areas of ﬂuid density

Answer 32

**Angiomyolipoma** The finding of fat attenuation values within a renal lesion on CT is diagnostic of angiomyolipoma. This is a benign tumour that is typically hyperechoic on ultrasound and of high signal on T1-weighted MR due to fat. It does not enhance post-gadolinium, in contrast to renal cell carcinoma, which usually does enhance

Answer 33

**Are associated with tuberous sclerosis** Those AML associated with tuberous sclerosis are multifocal, bilateral, larger and present in a younger age group. AML appear echogenic on US.

Answer 34

**AML** AML appears increased on S1 on T1+T2 and is echogenic on US.

Answer 35

**AML** Demonstration of fat within a renal mass on CT or MRI is diagnostic of AML

Answer 36

**haemorrhage from the angiomyolipoma** Angiomyolipomas are benign hamartomatous tumours that can occur in the kidneys. They contain fat, smooth muscle and abnormal blood vessels. Eighty per cent are sporadic and occur most often in females aged 50–80 years. Twenty per cent of patients with angiomyolipomas have tuberous sclerosis. Retroperitoneal bleed is the most signiﬁcant complication and can be catastrophic. The risk increases with size of the lesion due to increased abnormal vasculature. Haemorrhage occurs because of large tortuous vessels and aneurysms. Embolization is performed for symptomatic (ﬂank pain) angiomyolipomas, those that have bled at any size, and prophylactically when over 4cm.

Answer 37

**Angiomyolipomas** The lesions contain fat (negative Hounsfield units) and show vascularity within. With the history of fits, tuberous sclerosis should be considered as a diagnosis.

Answer 38

**Non-Hodgkin’s lymphoma** The most likely diagnosis is non-Hodgkin’s lymphoma. Primary renal involvement is rare but is often involved either by haematogenous spread or direct invasion. The kidneys represent one of the most common extra-nodal sites of disease in non-Hodgkin’s lymphoma but are rarely involved in Hodgkin’s disease. Involvement is usually bilateral, with masses of decreased attenuation and mild homogenous enhancement with intravenous contrast on CT. Patency of the renal vessels despite encasement is highly suggestive, as is preservation of the normal renal contour.

Answer 39

**CT may demonstrate sheet like diffuse infiltration of perirenal tissues** Diffuse infiltration leads to renal enlargement. Focal lesions have a characteristic usually low attenuation post-contrast on CT, low SI on T1 and hypo-iso-intense on T2

Answer 40

**Are usually hypo-vascular on CT** Metastases are usually small (< 3cm), multiple and confined to cortex. The most common mode of spread is haematogenous. Metastases tend not to invade the renal vein or calcify; they are more infiltrative, less exophytic compared with renal cell carcinoma

Answer 41

**Cortico-medullary phase**. Imaging in the **cortico-medullary phase (25-40 sec)** is helpful for showing the normal cortico-medullary pattern in pseudotumours such as prominent columns of Bertin or focal renal hypertrophy. It is also useful for suspected abnormalities such as vascular malformations and pseudoaneurysms of the kidney. The **nephrographic phase (70-180 sec)** is best to characterize renal masses. Small parenchymal renal lesions may be hidden in the renal medulla on the cortico-medullary phase and excretory phases. **Excretory phases(>180 sec)** are best to assess for collecting system lesions and the unenhanced scan is best for detection of renal calculi and for using as a baseline in assessing the enhancement characteristics of parenchymal renal lesions

Answer 42

**Hypertrophied column of Bertin** Many lesions may be mistaken for a renal cell carcinoma on imaging, and it is important to be able to differentiate such ‘pseudotumours’ from genuine carcinomas. The features described in the question are consistent with a prominent column of Bertin. This is normal renal tissue located between the pyramids and extending into the renal sinus. The key features include continuity with the cortex, identical echogenicity to normal cortex and the lack of mass effect or renal outline deformity. * A dromedary hump is a focal bulge on the lateral border of the left kidney caused by its relationship with the adjacent spleen. * Persistent fetal lobulation can be identified by indentations of the renal surface that overlie the space between the pyramids * Renal scarring lies directly over the medullary pyramids

Answer 43

**Sturge–Weber–Dimitri syndrome** This is characterised by multiple vascular malformations in the face (‘port-wine stain’) and central nervous system (leptomeningeal venous angiomas), and orbital and visceral angiomatosis (intestine, kidneys, spleen, thyroid, pancreas, and lungs). ## Footnote Syndromes with renal mass 1. Von-Hippel Lindau 2. Tuberous Sclerosis 3. Birt Hogg Dube 4. Sturge-Weber-Dimitri

Answer 44

**60 pre-contrast attenuation, 70 post-contrast attenuation.** The attenuation of the normal renal parenchyma typically ranges from 30 to 40 HU. That of hyperattenuating renal masses usually is at least 40 HU but no higher than 90 HU on CT without intravenous contrast. Benign cysts are overwhelmingly the most common type of hyperattenuating renal mass and are also known as hyperdense renal cysts. They are usually cysts containing haemorrhage or proteinaceous material. Hyperattenuating cysts should not enhance and therefore cannot be diagnosed with conﬁdence by using unenhanced CT alone. A proper CT examination includes scanning both before and after the administration of intravenous contrast material. Masses that increase in attenuation by 10 HU or less are considered non-enhancing. Masses that increase in attenuation by more than 10 HU are considered enhancing. However, because the standard deviation of attenuation measurements may be more than 10 HU, an attenuation difference of 20 HU or more is a more speciﬁc criterion of enhancement

Answer 45

**Multiple thin non-enhancing septa**. The criteria for a Bosniak IIF cyst are multiple hairline-thin septa with or without perceived (not measurable) enhancement, minimal smooth thickening of wall or septa that may show perceived (not measurable) enhancement, calciﬁcation may be thick and nodular but no measurable enhancement present, no enhancing soft-tissue components, and intrarenal non-enhancing high attenuation renal mass (> 3cm). The follow-up is CT or MRI at 6 months, 1 year, and then yearly up to 5 years. The criteria for a Bosniak II cyst that does not require follow-up include few hairline-thin septa with or without perceived (not measurable) enhancement, ﬁne calciﬁcation or a short segment of slightly thickened calciﬁcation in the wall or septa, homogeneously high- attenuating masses (<3 cm) that are sharply marginated and do not enhance. Thickened irregular or smooth walls or septa, with measurable enhancement, are features of a Bosniak III cyst and these are surgical lesions unless there are co-morbidities or limited life expectancy, when they may be observed

Answer 46

**Uniform wall thickening** The Bosniak classification groups cystic renal lesions into one of four categories based on CT/MR appearances. The differentiation between groups II and III is important as group II are typically ‘follow-up lesions and group III are ‘surgical lesions. Features of a Bosniak III lesion include irregular thickened septa, measurable enhancement, coarse irregular calcification, multi-loculation, nodularity, uniform wall thickening and margin irregularity

Answer 47

**III** Class II have at least one thin septa traversing them (< 1mm) and they have an appearance of thin areas of mural calcification or fluid content with greater attenuation. These lesions are benign however IIF with numerous class II features should be followed up. Class III features as above are indicative of malignancy and biopsy, or surgical exploration is necessary. Type IV cystic lesions are clearly malignant.

Answer 48

**Imaging follow-up** An incidental, mildly complicated renal cyst has been uncovered. The Bosniak classiﬁcation is a useful tool for evaluating cystic renal lesions, and guiding management. Simple cysts (Bosniak grade I) are thin walled, are of water density and have no enhancement. Minimally complicated cysts (grade II) may be clustered or septated, and have small curvilinear calciﬁcations, a minimally irregular wall or high-density contents. Follow-up lesions (grade IIF) have perceptible enhancement of otherwise thin septations or are above 3cm in diameter with high-density contents. Surgical lesions (grade III) have thicker septa or walls, measurable enhancement, coarse irregular calciﬁcation and irregular margin, are multiloculated or can be a non-enhancing nodular mass. Clearly malignant lesions (grade IV) can have necrotic components, irregular wall thickening and enhancing solid elements

Answer 49

**Localized cystic renal disease**. This is an uncommon, non-familial, and non-progressive disorder of the kidney characterized by the replacement of all or localized areas of a kidney by multiple variably sized cysts. These cysts form clusters that are separated by thin areas of normal renal parenchyma. The aggregated cysts in localized cystic disease can frequently appear like a multi-septate mass, but they do not form a distinct encapsulated mass and do not show mural irregularities, which are characteristics of cystic neoplasms. Multilocular cystic nephroma in adults is much more common in females (female:male 9:1) and manifests as a multi-loculated cystic lesion with hair-like septa and minimal mural enhancement. It is distinguished from localized cystic disease by the presence of a capsule. Typically, extension into the central renal sinus is found and multilocular cystic nephroma is often classiﬁed on imaging as Bosniak III lesions. Lymphangioma of the kidney is a rare benign cystic tumour that most often arises from the peri-pelvic region or renal sinus. It may more rarely arise from the lymphatics of the capsule or cortex. In the diffuse form of lymphangiomatosis, the cystic changes occur diffusely in the renal sinus or perinephric region, with a relatively normal appearing renal parenchyma. Clear cell RCC presents as a solid or a cystic lesion, the cystic variant accounting for 4–15% of all RCCs. These lesions typically have nodular or septal enhancement, distinguishing them from benign cystic renal lesions. Multi-cystic dysplastic kidney is a congenital maldevelopment in which the kidney is completely replaced by cysts with no normal renal parenchyma remaining.

Answer 50

**Haemorrhagic renal cyst** A less than 10 HU increase post-contrast indicates benign hyperdense cyst. Other benign features include being sharply marginated and homogenous

Answer 51

**Parapelvic cysts** The main differential diagnosis for a parapelvic or renal sinus cyst is hydronephrosis. Such cysts may present with pain due to obstructive caliectasis, but rarely cause hydronephrosis. They are found in 1.5% of autopsies and represent 4–6% of all renal cysts. A distinction is made in this question between renal and ureteric colic, the former symptom located to the loin and the latter more typically being loin to groin

Answer 52

**Medullary sponge kidney**. Hyperparathyroidism, renal tubular acidosis, and medullary sponge kidney are the three most common causes of medullary nephrocalcinosis. The former two conditions are associated with hypercalciuria that results in uniform medullary nephrocalcinosis. Sarcoidosis and multiple myeloma are associated with hypercalcemia resulting in bilateral nephrocalcinosis. Medullary sponge kidney can affect the kidney segmentally, unilaterally, or bilaterally, therefore unilateral nephocalcinosisis is suggestive of medullary sponge kidney. Medullary sponge kidney is characterized by **cystic dilatation of collecting tubules**. Urine stasis within the dilated tubules **predisposes to infection and calculus formation** within the dilated tubules or urinary tracts. On excretory urogram, **contrast within the dilated tubules produces a striated ‘paintbrush’ appearance of the renal pyramids**.

Answer 53

**Medullary sponge kidney** The features are those of medullary sponge kidney. This is a non-inheritable condition that produces cystic dilatation of the collecting ducts and nephrocalcinosis; 75% of cases are bilateral and it is usually asymptomatic. It is associated with an increased incidence of infection and urolithiasis but is not thought to predispose to malignancy

Answer 54

**Medullary cystic disease** Acute arterial hypotension, arteriosclerosis, nephrosclerosis and hereditary nephropathies including medullary cystic disease and Alport syndrome are all causes of bilateral small kidneys.

Answer 55

**Autosomal dominant polycystic kidney disease** Intravenous urogram appearances are typical due to large cysts distorting the collecting system. **Spider leg pyelogram - Stretched out collecting system due to mass effect from renal cysts** Autosomal recessive polycystic kidney disease (infantile type) produces microscopic cysts and on intravenous urography and shows an initial faint nephrogram with increasingly dense nephrogram.

Answer 56

**Autosomal recessive polycystic kidney disease** This condition can be diagnosed as early as 17–18 weeks on obstetric ultrasound. The kidneys may be massively enlarged measuring up to 10–20 times normal size with an enlarged renal: abdominal circumference ratio of > 0.30. The renal parenchyma is hyperechoic and there may be oligohydramnios. There is an association with congenital hepatic fibrosis.

Answer 57

**Renal tuberculosis** This appearance is typical of a ‘putty kidney’. This results in a non-functional, shrunken kidney and auto-nephrectomy. Tuberculosis can involve any part of the genitourinary tract. Renal tuberculosis is usually seen secondary to haematogenous spread from lungs. Renal tuberculosis can manifest in several ways including as a renal mass

Answer 58

**Emphysematous pyelitis**. The combination of these radiological ﬁndings in a septic diabetic patient indicates an infection with a gas-forming organism, usually E. coli. The gas is located entirely within the pelvicalyceal system, as opposed to the renal parenchyma, which would indicate a diagnosis of emphysematous pyelonephritis. The importance is in the urgency of treatment and prognosis. Emphysematous pyelonephritis carries a grave prognosis and often requires nephrectomy for life-saving treatment, whereas the prognosis with emphysematous pyelitis is not as grave and it often responds to antibiotics with possible urinary drainage procedures if necessary.

Answer 59

**Xanthogranulomatous pyelonephritis (XGP)**. This is most commonly secondary to Proteus infection. XGP is discussed elsewhere in this chapter.

Answer 60

**XGP**. Whilst the patient presents with the classical renal cell carcinoma (RCC) triad of loin pain, haematuria, and a mass, this triad is actually only present in 30% of patients with RCC. These features are also typically found in XGP. The key ﬁnding in this case is of areas of **fatty attenuation within the mass, in association with a staghorn calculus**. Calculi are found in 80– 90% of cases of XGP. The long history of symptoms is also typical of XGP, which can be present for up to 6 months prior to diagnosis. Lymphoma, RCC, and renal oncocytoma would not typically have areas of fatty tissue within them. Angiomyolipomas, in the absence of tuberous sclerosis, are typically solitary. They are usually well deﬁned, unlike in this case, and would rarely reach this size without having previously caused symptoms. XGP is typically found in **diabetic patients** and is due to **proteus infection**. Treatment is with **nephrectomy**

Answer 61

**Xanthogranulomatous pyelonephritis** The most likely diagnosis is xanthogranulomatous pyelonephritis. This is a chronic granulomatous infection in a chronically obstructed kidney, often secondary to a staghorn calculus. It often presents insidiously in middle-aged to elderly females. It is most commonly diffuse, but the focal form seen in 15% of cases may provide a diagnostic dilemma as it can be difficult to confidently distinguish from renal cell carcinoma.

Answer 62

**Xanthogranulomatous pyelonephritis** A rare form of low-grade chronic renal infection with progressive destruction of renal parenchyma, XGP is more common in women and in 50-60 age group. Most cases are diffuse. E.coli and P.mirabils are the most common organisms in these patients with UTI

Answer 63

**Xanthogranulomatous pyelonephritis** On the IVU, the features of xanthogranulomatous pyelonephritis are unilateral reniform enlargement, ipsilateral renal hypofunction and nephrolithiasis. The condition is probably produced by chronic low-grade obstruction and chronic bacteriuria. Renal parenchyma is replaced by lipid-laden histiocytes causing renal expansion. This expansion can cause ‘stone fracture’ with obvious separation of the fracture fragments on plain ﬁlm. Renal tuberculosis causes dystrophic calciﬁcation that can be nodular, curvilinear, or amorphous. The calciﬁcation is typically multifocal, involving other sites of the urinary tract, and there may be kidney scarring. Hyperparathyroidism causes medullary calciﬁcation. Six per cent of renal carcinomas have amorphous, irregular, or occasionally curvilinear calciﬁcation, while hydatid cysts exhibit curvilinear or heterogeneous calciﬁcation.

Answer 64

**Xanthogranulomatous pyelonephritis** This is a chronic suppurative infection characterised by replacement of renal parenchyma by lipid-laden macrophages. In most cases there is also a staghorn calculus with renal enlargement and a rim of cortical enhancement (‘bear paw’ sign)

Answer 65

**Xanthogranulomatous pyelonephritis** Other options are all associated with bleeding or spontaneous haemorrhage.

Answer 66

**Perinephric and periureteric stranding**. Whilst this observation is sensitive and speciﬁc for detecting calculi, it does not have a bearing on stone outcome or urgency of treatment. The site is of value because if the stone impacts, it dictates the therapeutic approach. The size of the calculus can be used to assess the likelihood of spontaneous passage, with calculi over 5 mm more likely to cause obstruction. The density of the calculus has been found to predict the success of extracorporeal shock wave lithotripsy (ESWL). The presence of anatomical variations is also of interest to the urologists in treatment planning, if this becomes necessary.

Answer 67

**HIV-positive patient on antiretroviral therapy**. Whilst CT KUB has 95–99% sensitivity for renal calculi, occasionally calculi due to antiretroviral therapy can be undetectable even to CT. Proteus is associated with formation of staghorn calculi and chronic dehydration with calcium oxalate calculi, both of which are radio opaque. Xanthine calculi and urate calculi are classically not detectable on plain ﬁlm KUB but are usually visible on CT KUB.

Answer 68

**Soft-tissue rim sign** The soft-tissue rim sign is thickening of the ureteric wall around the calculus due to oedema. It has a reported specificity of up to 92% for renal calculi. Other signs that may favour a diagnosis of ureteric calculi include asymmetrical perinephric fat stranding, periureteral oedema, hydronephrosis and unilateral renal enlargement. The lobster claw and signet ring signs concern papillary necrosis on intravenous urogram. The nubbin and drooping lily signs both refer to ureteral duplication.

Answer 69

**T1-weighted imaging is useful in differentiating between clot and calculi** * A static-fluid MR urogram is a heavily T2-weighted technique like MRCP. * Excretory urogram is a post-gadolinium injection T1-weighted technique. * A static-fluid MR urogram is preferred in patients with renal failure. * Renal sinus cysts cannot often be differentiated from dilated intrarenal collecting systems on T1-weighted and T2-weighted images. They are better appreciated on the excretory urogram. Source data should be reviewed to ensure that small filling defects are not missed.

Answer 70

**In an obstructed infected system, further imaging and manipulation are usually delayed after establishing drainage** * The most common reasons for persistent haematuria are traumatic arteriovenous fistula, pseudoaneurysm or vascular injury, all of which are usually managed endovascularly. * Brodel’s avascular plane is just posterior to the convex lateral margin. * Whilst an easily accessible lower pole calyx is usually the target for a simple nephrostomy drainage, for ureteral interventions, a posterior calyx in the mid or upper polar region may be better. * Almost all patients develop haematuria, but 1–3% may need transfusion or further intervention.

Answer 71

**Post obstructive uropathy** Answers B-E are causes with narrow infundibula.

Answer 72

**HIV** While around 10% of renal and ureteric stones are radiolucent on plain ﬁlm, almost all are opaque on CT. One exception is the tiny radiolucent calculi formed in patients on protease inhibitors such as indinavir used in the treatment of HIV/AIDS.

Answer 73

**Left nephrostomy and antibiotics** Pyonephrosis secondary to an obstructing calculus is the likely diagnosis. Percutaneous nephrostomy is indicated for temporary or permanent relief of an obstructed urinary system (malignant or benign obstructive uropathy), pyonephrosis, renal stones, iatrogenic ureteric injury, transplant kidney ureteric obstruction, and vesicovaginal ﬁstula. A ‘onestab’ puncture technique or Seldinger technique can be used. For any procedures where urinary infection is suspected or in stone disease, prophylactic antibiotics are mandatory – for example, 80mg gentamicin or 750mg cefuroxime. Clotting must also be checked and if necessary corrected. The major complication rate is around 3% while minor complications occur in around 15%. Major complications are septicaemia, blood loss requiring transfusion, pleural or abdominal viscera puncture, or transcolonic approach. Minor complications include retroperitoneal urine extravasation, clot colic from macroscopic haematuria and tube complications. Tube complications include catheter dislodgement, blockage, leaking, kinking and fracture

Answer 74

**Acute tubular necrosis** Acute tubular necrosis is the commonest acute reversible cause of renal failure in the transplanted kidney and usually occurs within 24 hours. Of the complications of a transplanted kidney causing renal impairment, **normal perfusion is seen in acute tubular necrosis**, whereas **renal vein thrombosis and transplant rejection have reduced perfusion accompanying the diminished excretion**. Ciclosporin can cause a similar pattern of renal impairment but would be expected to occur 1 month after transplantation. Functional assessment of a transplanted kidney involves perfusion and excretion assessment with a MAG3 or DTPA renogram, MAG3 being the better test in transplant recipients with renal impairment. Doppler ultrasound resistive index measurement is also used, with a value of ,0.7 regarded as normal.

Answer 75

**Chronic non-steroidal anti-inﬂammatory drug (NSAID) analgesic overuse**. The appearances described are those of **renal papillary necrosis**. This can be due to several causes, most commonly analgesic abuse, but also severe renal infection in diabetics, sickle cell disease, haemophilia, and renal vein thrombosis. The causes of chronic renal disease can be subdivided by the effects noted on the renal parenchyma and the papillary/pelvicalyceal system, and whether these are uni- or bilateral. In bilateral cases such as this, no radiological abnormality suggests possible glomerulonephritis, acute tubular necrosis (ATN), acute cortical necrosis, or pyelonephritis. Generalized inﬁltration of the renal parenchyma suggests amyloid or malignant inﬁltration (e.g. lymphoma or leukaemia). Papillary/pelvicalyceal abnormalities, in the presence of normal parenchyma, indicate papillary necrosis, medullary sponge kidney, or renal TB. Papillary calyceal abnormality with focal parenchymal loss indicates reﬂux nephropathy, TB, or calculus. Both parenchymal loss and papillary calyceal abnormalities indicate obstructive nephropathy or severe reﬂux nephropathy.

Answer 76

**Papillary necrosis** Papillary necrosis occurs due to ischaemic damage to the medulla of the kidney and does not primarily involve the cortex. There are many causes including diabetes, analgesic nephropathy, pyelonephritis, renal vein thrombosis and sickle cell disease. It may be localised or diffuse, bilateral or unilateral depending on the cause. Intravenous urogram appearances are varied and include clubbed calyces, calcification and sloughing of necrotic papilla and alteration in the renal contour.

Answer 77

**Sickle Cell Disease** Causes of bilateral smooth renal enlargement include diabetic nephropathy, acute glomerulonephritis, collagen vascular disease, vasculitis, AIDS nephropathy, leukaemia, lymphoma, autosomal recessive polycystic renal disease, acute interstitial nephritis, sickle cell disease, thalassaemia, acromegaly, amyloidosis, myeloma, and acute urate nephropathy. When the bilateral renal enlargement is caused by masses, the differential diagnosis includes autosomal dominant polycystic disease, acquired renal cystic disease, lymphoma, metastases, Wilms’ tumours, tuberous sclerosis, von Hippel–Lindau syndrome, multiple oncocytomas and nephroblastomatosis.

Answer 78

**Sloughed papilla** Predisposing factors to papillary necrosis include diabetes mellitus, analgesic nephropathy/abuse, sickle cell disease, pyelonephritis, obstructive uropathy, tuberculosis, trauma, cirrhosis, coagulopathy and renal vein thrombosis. None of the other options easily explains the club-shaped calyx. Blood clots from renal or tumour haemorrhage do cause ureteric colic but tend to elongate along the pelvis and ureter

Answer 79

**Acute tubular necrosis** This is secondary to temporary marked reduction in tubular blood flow. Contrast injection especially in diabetics with glomerulosclerosis is one of the known causes. Typically, the kidneys are enlarged due to interstitial oedema with an immediate dense and persistent nephrogram with absence of contrast from the collecting system.

Answer 80

**Acute cortical necrosis** The features described are typical of cortical nephrocalcinosis. Causes of cortical nephrocalcinosis include acute cortical necrosis, chronic glomerulonephritis, sickle cell disease, Alport syndrome and congenital oxalosis. Acute cortical necrosis is a rare cause of acute renal failure and is most commonly due to complications of pregnancy such as placental abruption, infected abortion, and severe eclampsia.

Answer 81

**Acute Cortical Necrosis** Acute cortical necrosis causes cortical nephrocalcinosis, whereas B-E are causes of medullary nephrocalcinosis.

Answer 82

**Renal cortical necrosis** This is rare cause of acute renal failure with typical imaging features as given. CT is the most sensitive and specific imaging for this condition. Absent opacification of the cortex with enhancement of juxtamedullary kidney and poor contrast excretion is diagnostic for this condition.

Answer 83

**Occurs in 90% of pregnant women by third trimester** In most women dilatation disappears postpartum. Resolution can take between a few days to several weeks. Maternal hormones play a minor part. Right sided hydronephrosis is more common

Answer 84

**There is no evidence of pelvi-ureteric junction or ureteric obstruction** The Whitaker test is a pressure–ﬂow study to evaluate ureteral obstruction or resistance in dilated non-reﬂuxing upper tracts. Being invasive and time-consuming, it is usually performed only when excretory renograms are equivocal. A pressure difference of greater than 15cmH 2 O is abnormal.

Answer 85

**Urine leak**. Lacerations generally contain clotted blood and therefore do not enhance on scans obtained with intravenous contrast. Contrast enhancement during the pyelographic phase of the CT examination indicates the presence of a urine leak. A delayed scan of 10–15 minutes may show the extent of the urinary extravasation. Intense enhancement within a laceration during the early phase indicates active haemorrhage. Focal areas of infarction do not enhance (unlike contusions). The cortical rim nephrogram is a sign of a devascularized kidney, which occurs due to laceration of the main renal artery.

Answer 86

**Deep laceration to the collecting system**. Renal injuries are classiﬁed into ﬁve grades of severity by the American Association for the Surgery of Trauma (AAST), with approximately 80% classiﬁed as grade 1. Most signiﬁcant injuries manifest as haematuria and no signiﬁcant urinary tract injury occurs in the absence of gross haematuria and shock. In addition, most signiﬁcant renal trauma is associated with additional visceral injury.

Answer 87

**Transitional cell carcinoma (TCC).** The appearance of **ureteral dilatation around and below an intraluminal ﬁlling defect** is described as the **‘goblet’ sign**. This sign indicates that the ﬁlling defect is caused by a chronic process, which allows dilatation of the ureter immediately below to accommodate the lesion. In addition to TCC, this appearance may rarely be seen with metastatic disease or endometriosis. Chronic analgesic use is a risk factor for TCC. Pyeloureteritis cystica appears as multiple small ﬁlling defects in the renal pelvis and ureter, typically seen in diabetics.

Answer 88

**Maintenance of reniform shape**. Advanced TCC of the collecting system in the kidney can cause distortion of the renal architecture, but typically the reniform shape of the kidney is maintained. As RCC arises in the renal cortex, large tumours of this nature typically distort the normal renal outline Calciﬁcation can rarely occur in both RCCs and TCCs, although perhaps more commonly in RCC. TCC demonstrates calciﬁcation in less than 3%, when it is usually diffuse and punctate. Necrosis can occur in both large RCCs and large TCCs, giving a heterogenous enhancement pattern on CT. Renal vein invasion is a more typical manifestation of RCC and both these tumours may be hypo-vascular compared to normal renal parenchyma on a nephrographic phase of the CT examination.

Answer 89

**TCC is the most common tumour of the urinary tract** TCC is the commonest cancer in the urinary tract. Whilst a predominant majority of them develop in the bladder, the renal pelvis is the second commonest site. In the ureter, the upper ureter is the commonest site. Adenocarcinoma is the commonest tumour in the urachus. [???] Schistosomiasis is associated with squamous cell carcinoma.

Answer 90

**Have a broad base and frond-like morphology** Over 85% of TCCs are infiltrating papillary tumours. CT density is 8-30 HU, slightly higher than urine and lower than renal parenchyma. Post-contrast there is mild to moderate enhancement to 18-55 HU.

Answer 91

**Location in proximal third of ureter** Ureteral endometriosis is usually in childbearing age and in the lower third of ureters, often co-existent with other sites of abdominal and pelvic disease.

Answer 92

**IV** In the TNM staging of urothelial malignancies, T1 refers to invasion of the subepithelial connective tissue, whereas a T2 tumour invades the muscularis. T3 tumours in the renal pelvis invade the peri pelvic fat or renal parenchyma, whereas those in the ureter invade the periureteric fat. T4 tumours invade adjacent organs or perinephric fat, as in this case. For renal and ureteric transitional cell carcinoma, the group stages I–III are determined by the T status, all these stages having no involved nodes

Answer 93

**Internal Iliac** A short axis measurement of 7 mm or greater represents signiﬁcant enlargement of internal iliac nodes. Regarding other nodal regions, signiﬁcant enlargement for inguinal nodes is 10mm, for common iliac 9mm, for external iliac 10mm, for obturator 8mm and for retroperitoneal nodes between renal arteries and the aortic bifurcation 12mm. In addition to size, there may be morphological clues to nodal involvement by cancer. Clustering of nodes, round nodes, nodes with irregular capsules, and nodes sharing CT or MRI characteristics of the primary tumour (attenuation, signal, cystic or necrotic changes, and contrast- enhancement pattern) are features suggesting lymph node involvement.

Answer 94

**Grade 3**. Whilst most associated with congenital reﬂux in children, acquired reﬂux is also seen, most commonly due to bladder outlet obstruction or recurrent cystitis. **Vesicoureteric reflux grading:** Grade 1 reﬂux demonstrates reﬂux into the **ureter**. Grade 2 reﬂux into the **renal pelvis** Grade 3 **Mild pelvi-ureteric dilatation**. Grade 4 **Moderate** pelvi-ureteric dilatation and calyceal blunting, but **preserved** papillary impressions. Grade 5 **Markedly** dilated pelvis and tortuous ureter with **obliteration** of the forniceal angles and papillary impressions.

Answer 95

**Renal imaging**. Mullerian duct anomalies are associated with renal tract anomalies in up to 30% of cases due to the close embryologic relationship between the Mullerian and mesonephric ducts. The most common renal tract abnormality is renal agenesis. Other associated anomalies include duplicated collecting system, renal duplication, horseshoe kidney, crossed renal ectopy. and cystic renal dysplasia. Renal imaging is therefore essential in all patients with Mullerian duct anomalies. Surgical intervention is not required in patients with a unicornuate uterus and a non- functioning rudimentary horn.

Answer 96

**Eagle Barrett syndrome**. Eagle Barrett syndrome or prune belly syndrome is classically deﬁned as a triad of partial or complete absence of abdominal musculature (resulting in bulging ﬂanks), cryptorchidism, and urinary abnormalities as described above. In addition, several respiratory, GI, musculoskeletal, and cardiovascular anomalies are associated with this syndrome. It occurs almost exclusively in males. The cause and embryogenesis remain controversial. Bladder outlet obstruction, mesodermal arrest, and dysgenesis of the yolk sac have been proposed as possible causes.

Answer 97

**Vesico-ureteric reﬂux** The abnormality described on ultrasound is multicystic dysplastic kidney (MCDK). It is the most common form of cystic disease in infants and the second most common cause of an abdominal mass in a neonate (after hydronephrosis). Obstruction/atresia of the ureter during the developmental stage is thought to be the etiology. Bilateral MCDK is uncommon, but associated anomalies of the contra-lateral kidney are seen in up to 50% of cases. Vesico-ureteric reﬂux (30–40%) is the most common associated anomaly, followed by pelvi-ureteric junction obstruction (10–20%).

Answer 98

**Retrocaval ureter** aka Circumcaval ureter Medial deviation of the ureter is seen with retrocaval ureter on the right side and with retroperitoneal fibrosis. The other conditions listed all cause medial deviation of the ureter in the lumbar region. Retrocaval ureter is a rare entity which is caused by abnormal embryogenesis of the IVC. There may be symptoms of right ureteral obstruction and recurrent urinary tract infections.

Answer 99

**Primary megaureter** The primary megaureter occurs because of developmental aperistalsis of the distal ureter. The ureter tends to be dilated but straight in a congenital primary megaureter. Primary vesico-ureteric reﬂux and obstructive secondary megaureter tend to cause tortuous ureteric dilatation.

Answer 100

**Left ureteral duplication** The ‘drooping ﬂower’ appearance on IVU occurs with a duplicated system when the obstructed dilated upper pole collecting system displaces the contrast-opaciﬁed, lower collecting system laterally and inferiorly. The Weigert–Meyer rule describes the commonest relationship of insertion of the duplicated ureters into the bladder. The upper collecting system ureter inserts ectopically into the bladder inferior and medial to the orthotopic ureter, which enters the bladder near the trigone. The ectopic ureter may be stenotic or obstructed with or without ureterocele

Answer 101

**Vesicoureteral reflux usually present** With an abnormal urinary tract, there may be failure of fetal micturition and thus oligohydramnios. This is seen exclusively in men and reflux is present in most cases. The bladder neck is typically wide with a tapering dilatation of the posterior urethra.

Answer 102

**Grade II** Grade I is reflux only in the ureter and not into the pelvicalyceal system. Grade III is reflux into the pelvicalyceal system with mild dilatation of the ureter and pelvicalyceal system. Grade IV and V are more severe dilatations and tortuosity of the ureter and pelvicalyceal system

Answer 103

**Malakoplakia**. This is an inﬂammatory response to chronic E. coli infection. It is more common in females and in diabetic/immunocompromised patients. It most commonly occurs in the bladder and distal ureter and is multifocal in 75% of cases

Answer 104

**Malakoplakia** Malakoplakia is the most likely diagnosis based on the history provided. This is a rare granulomatous infection affecting **elderly females** with a history of E. coli infections. It primarily affects the bladder and affects the remainder of the renal tract with decreased incidence as one progresses proximally. **Leukoplakia** may have similar appearance, but is **more common in males** with bladder involvement, and is characterised by the **passage of gritty soft-tissue flakes.** **Pyeloureteritis cystica** typically produces multiple **round filling defects** rather than plaques.

Answer 105

**Extraperitoneal rupture**. Over 70% of patients with traumatic bladder injury have a coexisting pelvic fracture. CT cystography is as accurate as conventional cystography. Extraperitoneal rupture * accounts for 80% of all cases of traumatic bladder injury. * It occurs because of shearing forces or penetrating injury from bony fragments at the base of the bladder. * Contrast can also track down into the scrotum or thigh. Intraperitoneal rupture * (15% of cases) * follows a direct blow to a distended bladder, with the tear involving the bladder dome. Contrast will be seen to outline small bowel loops. Combined injuries occur in 5%. Interstitial injuries are rare and are detected by contrast dissecting into the bladder wall. Imaging is frequently normal in the setting of bladder contusion.

Answer 106

**Contrast extravasation into the paracolic gutters** Extraperitoneal rupture of the bladder is associated with pelvic fractures following trauma and cystography should be performed if this is suspected. The injury is usually at the base of the bladder, anterolaterally. Contrast is seen to extravasate with a streaky or flame-shaped appearance and collects in the space of Retzius, upper thighs, inguinal regions, perivesical fat and anterior abdominal wall. Contrast in the paracolic gutters suggests intraperitoneal rupture of the bladder. This is associated with a different method of injury, typically rupture at the bladder dome following blunt trauma with a distended bladder or secondary to iatrogenic injury such as cystoscopy.

Answer 107

**Invasion of peri vesical fat** Invasion of peri vesical fat indicates T3 disease. Invasion of surrounding organs, pelvic or abdominal wall is T4 disease. T1-T2b tumours are treated with a conservative approach including TURB and local chemotherapy, whereas radical cystectomy and urinary diversion are reserved for invasive cancer.

Answer 108

**T2 N2 M0** Bladder cancer achieves the T3 status by peri vesical involvement. The N status is determined by the greatest dimension of the regional nodes. When the greatest dimension is less than or equal to 2cm, the nodal status is N1. N2 is for regional nodes measuring 2–5cm. N3 is achieved when the greatest dimension of the largest regional node is more than 5cm. Inguinal and retroperitoneal nodes are staged as metastases.

Answer 109

**MRI of the bladder plus CT of the chest, abdomen, and pelvis with intravenous contrast** MRI is indicated for local (in fact locoregional) staging. CT of the chest is required in addition to the abdomen and pelvis because of the histological tumour type. 18 FDG PET is not useful for staging urothelial tumours because of the urinary excretion of this radiotracer.

Answer 110

**Emphysematous cystitis** Emphysematous cystitis occurs more commonly in females and is usually due to E.coli. Gas is present in the bladder mucosal lumen. On ultrasound there is a thickened bladder wall with echogenic foci and acoustic shadowing

Answer 111

**Bladder calciﬁcation** Whilst this can be seen in TB, it is more typically associated with schistosomiasis. TB usually causes scarring and a reduced capacity bladder. Renal calciﬁcation is typical. The areas of increased attenuation within the calyceal system represent areas of coalescing caseating granulomas and may have associated calciﬁcation. Scarring can also cause stenosis of calyces, causing focal obstruction. Occasionally a small calciﬁed kidney is found, evidence of auto- nephrectomy. Passage of the infection via the urine into the ureters causes focal stenoses, which can coalesce to cause a long stricture, or give a beaded or corkscrew appearance to the ureter. Whilst renal TB results from spread from a primary pulmonary infection, the CXR is only abnormal in 25–50% of cases and is therefore not helpful.

Answer 112

**Schistosomiasis** The differential for bladder calcification includes tuberculosis, post-radiotherapy cystitis, urachal carcinoma, TCC, and squamous cell carcinoma. However, schistosomiasis is the commonest cause, especially in the African population, where it is often endemic. The bladder is usually a normal size and shape, with thin curvilinear calcifications. Ureteric strictures, inflammatory pseudo-polyps and vesico-ureteric reflux are seen in addition to bladder and ureteric calcification.

Answer 113

**Schistosoma haematobium** Schistosomiasis (bilharzia) is a parasitic infection that, worldwide, is the commonest cause of bladder wall calciﬁcation. Schistosoma japonicum and S. mansoni cause gastrointestinal tract infection, while S. haematobium affects the genitourinary tract. Schistosomiasis is endemic in South Africa, Egypt, Nigeria, Tanzania, Zimbabwe and Puerto Rico. The calciﬁcation spreads proximally up the ureters. In contrast, tuberculosis begins in the kidneys and spreads distally. Transitional cell carcinoma and cyclophosphamide-induced cystitis also cause bladder wall calciﬁcation. Causes of calciﬁcation within the urinary bladder lumen include stones and encrusted foreign bodies such as catheter balloons.

Answer 114

**Cystocele** Suspected pelvic ﬂoor prolapse can be investigated with MRI. Usually, there is minimal movement of pelvic organs even on maximal strain. When the pelvic ﬂoor is lax, the organs descend below the pubococcygeal line by 1–2cm. When descent exceeds 2cm, the prolapse may require surgical intervention. An enterocele describes small bowel descending 2cm or more between vagina and rectum. Anterior bulging of the rectal wall is known as a rectocele, while bladder descent of more than 1cm is a cystocele

Answer 115

**Schistosomiasis** Schistosomiasis is endemic in southern and east Africa and is a result of infection by Schistosoma haematobium. Ova are laid into the submucosa of the lower urinary tract, causing an extensive fibrosing with later calcification. Ova migrating into the portal venous system result in a fibrosing granulomatous reaction leading to portal hypertension and oesophageal varices.

Answer 116

**Anterior urethral injury**. Urethral injuries are rarely life-threatening but have signiﬁcant long-term morbidity. Complications include stricture, incontinence, and impotence. The male urethra extends from the bladder base to the external meatus and is divided into the posterior (prostatic and membranous) and anterior (bulbous and penile) urethra. The anterior and posterior urethra are separated by the urogenital diaphragm. The Goldman classiﬁcation of urethral injury emphasizes anatomic location.

Answer 117

**Posterior urethral injuries can be seen in up to 20% of pelvic fractures in males** Urethral injuries are seen in up to 20% of male patients following pelvic fractures. They are much less common in women. The posterior urethra is the commonest site; impotence can develop in up to 40% of these patients.

Answer 118

**Retrograde urethrogram to exclude urethral injury** In patients with pelvic fractures, bloody meatus, and inability to void should raise the possibility of urethral injury. A retrograde urethrogram should be performed to exclude urethral injury before inserting a Foley’s catheter or cystography for bladder ruptures.

Answer 119

**Squamous cell** Urethral tumour is rare and occurs more in women than in men. Squamous cell carcinoma is the most common histological type followed by transitional cell carcinoma and then adenocarcinoma. MRI is the technique of choice for local staging

Answer 120

**Corpus spongiosum enhances more rapidly following gadolinium as compared to the corpora cavernosa** **Both** corpus spongiosum and the corpora cavernosa are **low on T1, High on T2**. The **periurethral** tissue is **low signal on T2** MR cannot reliably differentiate between Buck’s fascia and tunica albuginea. They are depicted as a single, thick, low-signal rim. A surface coil is used for local disease staging.

Answer 121

**Peyronie’s disease** The cause of Peyronie’s disease is unknown, but the result is ﬁbrous thickening of Buck’s fascia and the septum between the corpora cavernosa. Calciﬁed plaques are also seen. The ﬁbrous areas do not engorge with blood, causing the penis at erection to be bent; this can make intercourse painful or impossible. * Priapism is persistent painful erection of the penis but is not associated with penile calciﬁcation. * Zoon’s balanitis is an idiopathic lymphocytic inﬂammatory condition of the penis, which may respond to topical steroid but is also treated by circumcision. * Balanitis xerotica obliterans is the severe form of penile lichen sclerosus, which is an uncommon inﬂammatory dermatosis. It can cause phimosis and urinary retention.

Answer 122

**Tunica albuginea** Invasion of the corpora cavernosa or corpora spongiosa by a penile cancer is via the tunica albuginea, making the local stage T2. If the urethra, found centrally within the corpora spongiosa, is involved, it becomes T3. Each corpus cavernosum contains a central artery. Having rapidly ﬂowing blood, this will also be hypointense on both T1W and T2W images because of ﬂow void.

Answer 123

**To perform local staging** MRI offers good soft-tissue contrast that is of value in local staging of the primary tumour. Local extent is used to guide the type of treatment, which includes partial penile amputation, total penectomy and radiation therapy. MRI will also show enlarged regional lymph nodes, but the principal purpose of MRI is local staging. CT can also be used for nodal spread and metastatic disease.

Answer 124

**Normal appearance** Investigation in most cases of haemospermia is not fruitful. In patients under 40 years, the causes are usually idiopathic or inﬂammatory (prostatitis, epididymo-orchitis, urethritis and urethral warts). The same causes apply in those over 40 years, but further possible causes include prostate cancer, benign prostatic hypertrophy, prostatic or seminal vesicle calculi, hypertension and carcinoma of the seminal vesicles

Answer 125

**Post-contrast enhancement less than that of all corpora** Most cancers of the penis (95%) are squamous cell carcinoma, but basal cell carcinoma, sarcoma, melanoma, lymphoma and urethral transitional cell carcinoma are also possible. Typical appearances of a primary penile cancer are of an ill-deﬁned inﬁltrating lesion hypointense to the corpora on both T1W and T2W images. Tumours enhance following contrast, but to a lesser degree than the normal corporal bodies. Signal characteristics of melanotic melanoma will be notably different from the other tumour types, returning a bright signal on T1W images.

Answer 126

**Repeat scan in 4 weeks**. There are a number of important points in this question. Firstly, the date from biopsy must be known to avoid misinterpreting haemorrhage as disease on MRI. Fortunately, the urologists have provided you with the salient information necessary to estimate disease stage from the Partin’s tables. Whilst these are clinical features, they are essential to know when interpreting MRI. The features described indicate a <1% risk of this patient having extracapsular disease. In combination with the unknown date of the biopsy, it would be prudent to exclude the possibility that this low signal in the seminal vesicles is not haemorrhage by repeating the scan. If this does represent disease invasion of the seminal vesicles, then it would indicate T3b disease.

Answer 127

**All of them.** MRI is not a primary investigation in the diagnosis of prostate cancer, but it is used in staging known disease. Occasionally, in a patient with a high risk of prostate carcinoma, as in this case, when the urologists have repeatedly failed biopsies, MRI can be used to help guide biopsy. In this setting MRS can also be used to increase conﬁdence in the diagnosis. As with all prostate imaging for cancer, the results are more reliable in the peripheral zone due to the variability of appearances in the transitional zone. Choline is elevated in prostate cancer and is thought to reﬂect increased cell membrane turnover. Creatine, also detected on MRS, is unchanged. Polyamine is reduced. Citrate, which is stored in normal prostatic cells, is reduced, presumably because of reduced normal function within cancerous cells. The (creatine + choline)/citrate ratio has been used to help discriminate prostate cancer from normal prostate. The role of MRS in the transitional zone is unclear.

Answer 128

**Post-contrast, the peripheral zone enhances more than the central zone** The zonal anatomy is best depicted on T2-weighted images. The proximal urethra is not routinely identifiable unless the patient is catheterised or has had previous TURP. Seminal vesicles are bright on T2-weighted images; the low-intensity structures indicate the neurovascular bundles. The peripheral zone has a higher signal on T2-weighted images and enhances more.

Answer 129

**Bladder and rectal involvement are best seen on coronal image**s Bladder and rectal involvement are best appreciated on axial and coronal images. MR is much more accurate for prostatic volume assessment and CT usually overestimates prostatic volume.

Answer 130

**Tumour of the gland is low signal on T2** Tumour appears as a focus of low signal compared to the normal high signal peripheral zone on T2. **T3 disease indicates extracapsular extension** and/or seminal vesicle involvement. Tumour appears dark on ADC and bright on high b-value DWI images. **Obturator nodes are first to become involved.**

Answer 131

**Elevated choline: citrate ratio** Elevated choline + creatine: citrate ratio best describes MRS features of prostate cancer.

Answer 132

**Are low signal when invaded with tumour** Seminal vesicles may appear low in signal on T2 when atrophic, empty or with tumour involvement.

Answer 133

**Volume of prostate gland > 60 cc precludes brachytherapy** Contraindications to brachytherapy include a volume of over 60cc.

Answer 134

**T2 weighted images** These demonstrate the zonal anatomy of the prostate well. The prostatic urethra serves as a reference point. The peripheral zone returns high signal compared with the central or transitional zones.

Answer 135

**Peripheral zone lesion with low signal on T2** Prostatic carcinoma is best seen as an area of low signal intensity in the peripheral zone of prostate on T2. The normal glandular tissue returns high signal on T2 images.

Answer 136

**Solid and Cystic Components** Prostatic sarcomas represent 0.1% of all primary prostate malignancy in adults. Mean age is younger than that of adenocarcinoma. Typically presents as a large solid and cystic mass with rapid hypervascular and heterogenous soft tissue occupying all or most of the prostate

Answer 137

**T2c N1 M1 ** Being bilateral prostate-conﬁned disease, this cancer is T2c. Internal iliac, obturator, external iliac and sacral are the regional nodal groups. Common iliac, para-aortic and inguinal involved lymph nodes are regarded as metastases. T1 – Not radiologically visible, T2a – less than half of one side T2b – more than half of one side T2c – bilateral, T3a – breaches the prostatic capsule T3b – invades seminal vesicles, T4 – other pelvic tissue.

Answer 138

**Left Base** In staging prostate cancer with MRI, the large-FOV T1W sequence is useful for demonstrating haemorrhage (high signal), enlarged lymph nodes and bone metastases. Small-FOV T2W images of the prostate in axial, coronal and sagittal planes show the zonal anatomy well, with normal peripheral zone returning high signal. Cancer within the peripheral zone typically returns low signal on T2W images. Other typical ﬁndings in carcinoma of the prostate are increased relative peak enhancement, increased contrast wash-in rate, reversal of the choline plus creatine/citrate ratio on spectroscopy, restricted diffusion and increase in permeability on pharmacokinetic modelling.

Answer 139

Scrotum - **Superficial Inguinal** Penile body - **Superﬁcial Inguinal** Proximal penis - **Deep Inguinal** Testes - **Para-aortic nodes at the L1–2 level.** Appreciation of these patterns of lymph drainage is of vital importance when staging testicular, penile, and other scrotal malignancies

Answer 140

**Malignancy in an undescended testis** Lipoma of the cord will have a high signal on both T1-weighted and T2-weighted images. Neurofibroma will demonstrate a target sign on T2-weighted images and is of low attenuation on CT. Abscess will be clinically apparent, hypoechoic on ultrasound and have high signal on T2-weighted images. Haematomas are usually of higher attenuation on CT with varying appearances on MR, but do not demonstrate contrast enhancement.

Answer 141

**Hypoechoic small and harder testis** Absence of hydrocele and normal scrotal wall/skin are other features of chronic torsion.

Answer 142

**Tubular ectasia of the rete testis**. * Also known as: Cystic transformation of the rete testis * Results from: Partial or complete obliteration of the efferent tubules → Ectasia → Cysts * Frequently bilateral but may be asymmetric. * The site: In or adjacent to the mediastinum testis * Associated with: Epididymal cysts or spermatoceles. * The key: The elongated shape that replaces the mediastinum. Intratesticular varicoceles can occur, but they are very rare. It would be even rarer for it to be thrombosed. Testicular abscess would not usually be multi-cystic but would be more rounded with an irregular wall and low-level internal echoes. Testicular infarction usually manifests as a hypoechoic mass that is largely avascular. It is not usually cystic. Epidermoid cyst is a rare benign tumour of germ cell origin. It is usually rounded or oval and classically has a target or ‘onion skin’ appearance of alternating layers of hyper- and hypo- echogenicity. The outer wall is typically hyperechoic and sometimes calciﬁed.

Answer 143

**adeno-carcinoid tumour ** 30% of all para-testicular masses and most common benign neoplasm. Hamartomatous lesions are of probable mesothelial origin in young adults and usually present either as a painless mass or an incidental finding.

Answer 144

**65%** A bell-clapper deformity is described. This is bilateral in 50–80% of cases. High insertion of the tunica vaginalis on the spermatic cord means that this tunic completely surrounds the testis, epididymis and distal spermatic cord, allowing intravaginal torsion. Extravaginal torsion is rare and occurs when the testis and tunic twist at the external ring.

Answer 145

**Testicular microlithiasis** This occurs when there is a defect in the phagocytic activity of Sertoli cells leaving degenerated intratubular debris behind. This condition is usually asymptomatic and ultrasound appearances are typically as described. When testicular microlithiasis is discovered, regular follow up should be performed due to risk of developing a testicular neoplasm.

Answer 146

**Tubular ectasias of rete testis** This is usually seen in older men and is thought to be secondary to cystic dilatation of the rete testis. This is a benign condition and an important differential is teratoma. Ultrasound appearances and MRI features are characteristic. These lesions are isointense (sometimes undetectable) on T2 (unlike teratoma).

Answer 147

**Fournier’s gangrene** Fournier’s gangrene is a progressive necrotising fasciitis in men. Thickening of the scrotal skin and air in the subcutaneous layer are diagnostic

Answer 148

**Epidermoid cyst** These are the typical radiological appearances of an epidermoid cyst of testis. The ‘onion-ring’ appearance is secondary to alternating layers of compacted keratin and desquamated squamous cells. The water and lipid contents of the cyst result in high signal on both T1 and T2.

Answer 149

**Lymphoma**. Clinically testicular lymphoma is distinct from other testicular neoplasms in that it occurs in a much older age group. It is the most common testicular neoplasm over the age of 60 years. It is also the most common bilateral testicular neoplasm (up to 38% of cases). The epididymis and spermatic cord are commonly involved. The sonographic appearance is variable and indistinguishable from germ cell tumours. Typically, they are discrete hypoechoic lesions that may completely inﬁltrate the testicle. Primary leukaemia of the testis is rare, although it is a common site of leukaemia recurrence in children. The sonographic appearances are very variable, as the tumour may be unilateral or bilateral, focal or diffuse, hypoechoic or hyperechoic. Testicular metastases, other than those from lymphoma or leukaemia, are very rare. Primary sites reported include prostate and lung. They are generally seen in the setting of widespread disease and are rarely the presenting complaint. Seminoma is the most common germ cell tumour. The average age of presentation is approximately 40 years. It is typically uniformly hypoechoic on ultrasound and they are only rarely bilateral (2%). Granulomatous orchitis may manifest as a testicular mass, but this would be very unusual. Typically this process tends to involve the epididymis ﬁrst and to a much greater degree than the testis. Pathogens include TB, syphilis, fungi, and parasites

Answer 150

**The majority of extra-testicular tumours are benign** The epididymis is iso- or hyperechoic compared to the testis. Seminomas are homogenous masses and hypoechoic to the testis. Epidermoid cysts are the commonest intra-testicular benign neoplasm. Lipomas are the commonest benign tumours in the spermatic cord.

Answer 151

**Lymphoma** This is the wrong age group for Leydig cell tumour (childhood) and seminoma (around 40 years). Lymphoma is the commonest tumour in this age group. It is more likely to have a diffuse hypoechoic appearance and be bilateral as compared to metastasis, which usually presents with multiple focal lesions. Tuberculosis of the testis is most often secondary to epididymitis.

Answer 152

**Right sided tumours spread initially to aorto-caval lymph nodes** Late relapse > 2 years after CR, in absence of second primary tumour. Occurs in up to 7% of patients with less predictable pattern of nodal spread. NSGT form 40% of testicular GCT compared with 60% seminomatous. Left-sided tumours metastasize to left PA nodes below the level of the renal vein. Echelon nodes are usually right-sided, anterior to right psoas

Answer 153

**Seminomas** Ninety-ﬁve per cent of testicular tumours are germ cell tumours. Others include sex-cord and stromal tumours such as Leydig cell and Sertoli cell tumours. Primary lymphoma and metastases can also occur in the testicle. Non-seminomatous germ cell tumours include teratoma, embryonal carcinoma and choriocarcinoma, but these affect a younger population of 20–30 years. Ultrasound scan is the investigation of choice for detection of a testicular tumour and for assessing normality of the contralateral testicle. Seminomas present with mass or pain and are generally lobulated masses on ultrasound scan with hypoechoic ﬁbrovascular septations in which colour ﬂow can be visible. T2W MRI demonstrates uniform intermediate signal with band-like low-signal septa. There is contrast enhancement, especially of the septations. They rarely calcify, but, if they do, the calciﬁcation is speckled or stippled

Answer 154

**Serial serum tumour marker measurement with 3-monthly CT of the chest, abdomen, and pelvis for 1 year followed by 6-monthly CT of the chest, abdomen and pelvis for 1 yea**r. Stage 1, non-seminomatous, germ cell tumour patients should enter a surveillance programme of this type following orchidectomy. Such programmes are rarely used for seminoma, particularly when retroperitoneal radiation treatment is used. Rising tumour markers between surveillance scans or thereafter should provoke CT of the chest, abdomen, and pelvis plus ultrasound scan of the remaining testicle. If no new disease is identiﬁed, MRI of the brain is indicated

Answer 155

**Follow-up clinical examination and surveillance sonography** Atrophic mal-descended testes are at higher risk of developing malignancy, particularly seminoma, even after orchidopexy. The increased risk applies to the contralateral testicle also. Microlithiasis is also associated with testicular cancer. In combination, these features require clinical and sonographic follow-up.

Answer 156

**Malignant teratoma** Seminoma tends to spread to contiguous nodes with the primary sites being, for a right-sided testicular tumour, right para-caval and inter-aortocaval nodes just below the junction of the right renal vein and inferior vena cava. Left-sided testicular tumours usually spread ﬁrst to nodes just caudal to the left renal vein. Teratoma and other malignant, non-seminomatous, germ cell tumours of the testes can occupy mediastinal nodes without such direct cranial extension along the nodal groups. Nodes involved by seminoma tend to be soft-tissue density while nodes inhabited by non- seminomatous, germ cell tumours are frequently cystic. Metastases to the testicle are rare on account of the testicle being an immunologically privileged site with a blood–testicular barrier. Adenomatoid tumour is a benign epididymal lesion. Epidermoid tumour is also benign, appearing as an intratesticular, hypoechoic lesion, characteristically with an echogenic capsule. Classically, it assumes an ‘onion-skin’ appearance of concentric echogenic layers. Internal shadowing can be produced by calciﬁcation.

Answer 157

**AFP and b-hCG** The patient’s age and ultrasound ﬁndings favour a non-seminomatous germ cell tumour. These are associated with elevated serum AFP and b-hCG. Together, CA-125 and AFP are associated with hepatocellular carcinoma, while CA-125 is also associated with ovarian cancer. CA-15-3 and CEA together are serum markers associated with breast cancer. PSA is associated with prostate cancer as well as several benign prostate conditions. CA-19-9 is mainly associated with malignancy of the pancreas and biliary tree

Answer 158

**Para-aortic lymph nodes** The lymphatics from the testis accompany the veins to the retroperitoneal nodes between the bifurcation and the kidneys. The local inguinal nodes are involved only if there is invasion of the scrotal wall.

Answer 159

**The left testis is more susceptible to blunt trauma** The testis suffers blunt trauma against the thigh or the symphysis pubis and the right testis, being higher, is more susceptible. Intratesticular haematomas should be followed up to resolution to rule out an underlying neoplasm and rule out any ensuing complications such as abscess formation which may necessitate orchidectomy.

Answer 160

**Immediate surgical intervention** Testicular rupture is described; it is an indication for immediate surgical intervention to salvage the testicle and prevent anti-sperm antibody development (testicles are immune- privileged sites). Other consequences of testicular trauma are fracture, haematoma, and haematocele. Associated torsion may occur, due to trauma-stimulated, forceful, cremasteric muscle contraction.

Answer 161

**Renal Vein Thrombus** Differentiation of renal cell from transitional cell carcinoma is helpful for planning surgical treatment since transitional cell carcinoma of the renal collecting system requires the more extensive surgical procedure of nephroureterectomy. Renal vein thrombus is seen with renal cell carcinoma while all other options given are features of transitional cell carcinoma of the kidney. Delayed contrast CT offers a pyelographic phase on which collecting system, ureter and bladder ﬁlling defects are clearly demonstrated. A urothelial ﬁeld effect can occur, resulting in multiple transitional cell carcinomas throughout the renal tract. Renal cell carcinoma, as it expands, tends to distort the renal outline and is more likely to be peripheral and exophytic

Genito-urinary Flashcards

(186 cards)