[anatomy&imaging][module C]

Question 1

Answer 1

Normal USS. Axial Rt lobe • Common carotid (CCA), rt lobe (arrow, very homogenous) and trachea marked.

Question 2

Answer 2

Lt thyroid nodule (arrow) on axial and longitudinal views:

Question 3

Answer 3

Seen as asymmetric enhancement (i.e. brightness, arrowed) around trachea on CT:

Question 4

Answer 4

PET-CT shows the activity of the lesion. The very bright signal here (arrow) shows that the lesion is very metabolically active and is therefore suspicious for tumour.

Question 5

Answer 5

T2 MRI, showing a large intrasellar mass extending into the suprasellar region, in keeping with a pituitary adenoma. The mass is arrowed.

Question 6

Answer 6

The rounded dark lesions are cysts. • Normal kidney structure no longer visible.

Question 7

Answer 7

The kidney has been taken over by cysts o The majority are low density, but some are higher density (arrow) due to intracyst haemorrhage usually. • Note, there is no intravenous contrast on this scan (look at aorta and IVC) o This is because the patient had renal failure

Question 8

Answer 8

The cysts are well seen as bright lesions (water is bright on T2 MRI)

Question 9

Answer 9

Also note cysts in the liver due to the ADPKD

Question 10

Answer 10

MCA aneurysm arrowed

Question 11

Answer 11

CT 3D reconstruction

Question 12

Answer 12

Angiogram post coil

Question 13

Answer 13

Normal internal carotids bilaterally (solid arrow) • Thyroid cartilage seen anteriorly (dashed arrow)

Question 14

Answer 14

Slightly more superior slice • Left ICA occluded (arrow) o External carotid artery anterior to this is patent • Mild narrowing of right ICA (irregular medial aspect)

Question 15

Answer 15

Mild narrowing at origin of right ICA (arrow)

Question 16

Answer 16

In comparison, the left ICA is occluded. • The ECA is patent.

Question 17

Answer 17

Solid arrow marks the adenoma o There is background low level activity around this which is from the thyroid • The activity superior to this is normal activity within the salivary glands (dashed arrow).

Question 18

Answer 18

Transverse section just beneath the thyroid (which is not visible on this image o The lesion is marked with 4 x small crosses o Right common carotid marked with solid arrow o Trachea marked with dashed arrow

Question 19

Answer 19

SVC compressed to a bright dot (arrow). Surrounded by multiple lymph nodes (lower density) • Aortic arch seen on left

In this case the symptoms were due to diffuse large B-cell lymphoma (a tumour of the lymphatic cells), causing lymphadenopathy in the neck and mediastinum. The mediastinal nodes compress the SVC, causing a degree of obstruction to blood returning to the heart – this is turn leads to facial fullness as the blood is held up, and breathlessness due to swelling around the trachea.

Question 20

Answer 20

Slightly lower down than last slice. SVC (arrow) pushed up against ascending aorta. o Heterogenous right anterior mediastinal mass = partially necrotic (hence heterogenous) tumour. o Other anatomy: Asc + desc aorta, pulmonary artery bifurcation, both main bronchi

Question 21

Answer 21

Abnormal node in the right supraclavicular fossa (dashed arrow) and around right neck vessels (solid arrow; note the asymmetry compared to left)

Question 22

Answer 22

Right brachiocehalic artery and branches and SVC well seen • SVC compression (arrow) well seen!

Question 23

Answer 23

PET CT combines the anatomy of CT (but no contrast given here, so vessels not as well seen) with functional information on PET • The PET scan tells us about tissue activity. o Here we can see that the right anterior mediastinal tissue is very active (bright colour – see scale on the side of the image, the higher up the scale, the more active)

POST Tx

Question 24

Answer 24

The consolidation on the right is actually infarct (secondary to PE) – a partially occluded vessel (arrow) is seen at the top of the consolidation (this is partially patent medially).

Question 25

[moduleC]: Case 8. Swollen leg +dyspnoea

Answer 25

Large tumour (arrow) arising from the right kidney – underlying cause for thrombus, o Quite often if there is no obvious predisposing factor for a pulmonary embolus or DVT, we image the patient to rule out an underlying tumour

Question 26

[moduleC]: Case 8. Swollen leg +dyspnoea

Answer 26

The aorta is partially calcified. • The IVC lies next to this – this contains a dark filling defect (arrow), extending to the left common iliac vein, representing a DVT (that embolised to the lung). • Other anatomy seen: Bladder (bottom of image), Liver in RUQ.

Question 27

[moduleC]: Case 8. Swollen leg +dyspnoea

Answer 27

Upside-down tulip shaped device with multiple prongs (solid arrow) lying within the IVC, to the right of the spine. This is the IVC filter. o The tube (dashed arrow) above this is the delivery device which has been introduced via the jugular vein in the neck, negotiated through the SVC and right atrium down to IVC. The IVC under the filter has been opacified partially with contrast. o The mechanical device in the bottom corner is a pulse-oximeter on the patient’s finger.

Question 28

[moduleC]: Case 9. Back pain and sudden-onset leg weakness

Answer 28

Bone windows on CT (hence different appearance to other CT). This allows better visualisation of bone. a. Destruction of right vertebral pedicle (solid arrow) b. Very moth-eaten bone with loss of cortex (see lateral ribs, dashed arrow), due to tumour infiltration

Question 29

[moduleC]: Case 9. Back pain and sudden-onset leg weakness

Answer 29

This is at the level of the right pedicle destruction seen on CT o Note the loss of normal bright CSF space anterior to and to the right of the spinal cord (arrowed) (normal below)

Question 30

[moduleC]: Case 9. Back pain and sudden-onset leg weakness

Answer 30

Again CSF is bright • T12 vertebral collapse (count up from L5) o The posterior aspect of T12 encroaches on the spinal cord • This and the axial views are best for discussing the anatomy of the spine.

Question 31

[moduleC]: Case 9. Back pain and sudden-onset leg weakness

Answer 31

STIR images are great for seeing oedema / tumour. a. These show up as bright areas on STIR, but are relatively dark on T2. Involves the vertebral bodies but also the posterior elements such as the spinous processes (solid arrow). b. Also note that CSF and a cyst (dashed arrow) in the T11 vertebral body are bright on STIR images.

Question 32

[moduleC]: Case 10. Massive Spleen.

Answer 32

Axial and coronal images showing a massively enlarged spleen in the left upper quadrant:

Question 33

[moduleC]: Case 10. Massive Spleen.

Answer 33

The spleen can enhance slightly heterogeneously compared to the liver. Many different patterns are described – here it has a ring-like enhancement pattern. • The spleen is enlarging from the left upper quadrant to the right lower quadrant (best seen on the coronal image). This is why one starts examining for splenomegaly from the right lower quadrant. • The patient has massive splenomegaly (= over 1 kg weight!). Causes include: a. Malaria b. Chronic myeloid leukaemia c. Myelofibrosis d. Kala-azar (visceral leishmaniasis) – this was the cause in this patient. • Leishmaniasis is caused by parasitic protozoa of the genus Leishmania. Humans are infected via the bite of phlebotomine sandflies, which breed in forest areas, caves, or the burrows of small rodents. There are four main types of the disease: a. Cutaneous (skin ulcers) b. Diffuse cutaneous (disseminated and chronic skin lesions resembling those of lepromatous leprosy). c. Mucocutaneous forms (lesions can partially or totally destroy the mucous membranes of the nose, mouth and throat cavities and surrounding tissues). d. Visceral leishmaniasis (aka “kala-azar”), is characterized by high fever, substantial weight loss, swelling of the spleen and liver, and anaemia. If left untreated, the disease can have a fatality rate as high as 100% within two years.