Jason H's flashcards COPY
1
Q
Cutoff for short cervix
A
Endocervical canal < 2.5 cm in length
2
Q
Max normal nuchal fold thickness and when to measure
A
Max nuchal fold thickness: < 6mm When to measure: ~18-22 weeks
3
Q
Classic differential for polyarteritis nodosa (PAN)
A
CLASH: - Cryoglobulinemia - Leukemia - Arthritis (rheumatoid) - Sjogren’s - Hepatitis B
4
Q
Hepatic angiosarcoma risk factors
A
- Thorotrast - arsenic - PVC - Radiation - Hemochromatosis - NF
5
Q
Carney Triad
A
- Pulmonary Chondroma - Extra-adrenal Pheo - GIST
6
Q
Wolman disease
A
Bilateral enlarged calcified adrenals
7
Q
Qualities making a thyroid nodule more suspicious
A
- More solid - calcs (esp. microcalcs - buzzword for papillary cancer) - cold on I-123 scan (15% cancer) - taller than wide - microlobulated contour - hypoechogenicity
8
Q
IgG4 associated diseases
A
- Orbital pseudotumor - Tolosa Hunt - Sialadenitis, dacryoadenitis (salivary, lacrimal gland inflammation) - Reidel’s thyroiditis - Autoimmune pancreatitis - Primary sclerosing cholangitis - Retroperitoneal fibrosis
9
Q
Whole body nucs scan showing bones, and spleen > liver. Which tracer?
A
Indium-111 WBC scan
10
Q
Nucs scan showing bones, liver > spleen, lacrimal glands. Which tracer?
A
Gallium
11
Q
Whole body nucs scan without bones but with liver > spleen. Which tracer?
A
I-131 MIBG
12
Q
Whole body nucs scan, no bones, spleen > liver, intense renal uptake. Which tracer?
A
In-111 Octreotide
13
Q
Whole body nucs scan, no bones, liver or spleen. Which tracer?
A
I-123 or I-131
14
Q
What tracers give you a very hot spleen?
A
In-111 octreotide, In-111 or Tc-99 WBC scans. Tc-99 sulfur colloid also, but the liver will be hotter.
15
Q
Things that can cause free Technetium on bone scan
A
Air in the vial/syringe (causes oxidation, releasing tech from MDP), or not enough stannous chloride (this reduces free pertechnetate, allowing binding to MDP)
16
Q
Marked uptake in skull sutures on MDP bone scan
A
Renal osteodystrophy
17
Q
Renal CORTEX hotter than adjacent lumbar spine on MDP bone scan?
A
Hemochromatosis
18
Q
Tc-99m half life?
A
6 hours
19
Q
Causes of liver uptake on Tc-99m MDP bone scan?
A
- Al 3+ contamination - cancer (HCC or mets) - amyloidosis - liver necrosis
20
Q
Reasons for diffusely DECREASED bone uptake on MDP bone scan?
A
- Free Tc-99 (less tracer bound to MDP) - bisphosphonate therapy
21
Q
Time frame for flare phenomenon on bone scan?
A
2 weeks - 3 months after treatment, bone scan may look worse. Signs it isn’t real: - lesions more sclerotic on CT - bone scan improves after 3 months
22
Q
Differential for cold lesion on MDP bone scan?
A
- Early osteonecrosis - Radiation therapy - Anaplastic met (thyroid, renal, neuroblastoma, myeloma) - Infarction (very early or late) - Hemangioma - Artifact from prosthesis
23
Q
“Tram track” uptake in long bones on MDP bone scan?
A
Hypertrophic pulmonary osteoarthropathy - main concern in lung cancer (seen in 10% of lung cancers), but also can be seen with any hypoxia inducing process, i.e., CF, CHF, mesothelioma, pneumoconiosis, etc.
24
Q
“Double density sign” on MDP bone scan
A
Osteoid osteoma. Sign describes hot area with even hotter area within it (the nidus).
25
Where do you tend to see VENOUS epidural hemorrhage?
Anterior temporal lobe
26
How to tell metabolic from metastatic MDP superscan?
Metabolic superscan will have super hot skull. Also, metastatic is more axial skeleton, while metabolic includes appendicular more.
27
Causes of metabolic superscan on MDP bone scan?
- Hyper PTH - renal osteodystrophy - diffuse Pagets - severe thyrotoxicosis
28
Normal plain film after equivocal lesion on MDP bone scan - more or less suspicious for met?
MORE suspicious. Next step should be MRI.
29
What are the cutoffs for IVC filter size (IVC diameter)?
IVC up to 28 mm can use normal Greenfield or Denali, up to 40 mm can use birds nest, if larger than 40 mm must place bilateral iliac vein filters.
30
What do you see in osteomyelitis on combined sulfur colloid/WBC nucs scan
Looking for an area of mismatch, where there is increased uptake on WBC scan (leukocyte infiltration) without increased uptake on marrow/sulfur colloid scan (normal marrow replaced by infection).
31
Half life of I-123
13.2 hours (switch 2 and 3 in I-123)
32
Half life of I-131
8 days
33
I-123 thyroid scan dose
100-400 microCi
34
Dose for MDP bone scan
20-25 mCi
35
F-18 FDG half life
109.7 minutes
36
F-18 FDG energy?
511 keV
37
F-18 FDG dose?
10-15 mCi
38
Dose of CCK before HIDA?
0.02 MICROgrams
39
Dose of morphine for HIDA scan?
0.04 mg
40
Tc-99m energy?
140 keV
41
Allowable breakthrough of Mo-99 per mCi Tc-99?
0.15 microCi per mCi Tc-99
42
I-131 energy?
364 keV
43
Things hot on all phases of 3 phase bone scan?
- Reflex Sympathetic Dystrophy (RDS) - Charcot joint - Osteomyelitis - Fracture - Tumor - Pagets (according to QEVLAR)
44
Radiation level below which noncancer fetal health effects not detectable in pregnancy?
\< 5 rads (0.05 Gy)
45
Differences between ovarian fibroma and Brenner tumor?
Both are fibrous ovarian masses, therefore dark on T1 and T2. Fibroma: - calcs rare Brenner: - calcs common - epithelial tumor (ovarian transitional cell carcinoma) - seen in older women (50s - 70s)
46
Name the different cysts in the region of the vagina?
Nabothian: cervix Gartner: Anterolateral wall of the upper vagina. Above level of the pubic symphysis on saggital. Can exert mass effect on urethra. Forms from incomplete Wolffian duct regression. Skene: Periurethral glands, so right above vaginal introitus. Bartholin: Below level of pubic symphysis, associated with labia majora.
47
Testicular mass with "onion skin" appearance?
Epidermoid cyst - benign - relatively nonvascular
48
Meigs syndrome?
- Benign ovarian tumor (fibrothecoma/fibroma) - Ascites - Pleural effusion/hydrothorax (right sided ~60-70%)
49
RCC T-staging?
T1, T2: Confined to kidney, less than (T1) or greater than (T2) 7cm. T3: Vascular invasion, a, b, c based on degree of invasion - - T3a: Renal vein invasion - T3b: Tumor extension in IVC, but below level of diaphragm - T3c: IVC extension above level of diaphragm T4: Extension beyond Gerota's fascia, or to ipsilateral adrenal gland
50
Things associated with Horseshoe kidney?
- Turners syndrome - Recurrent stones and infection - Wilms tumor (8x increased risk) - Transitional cell carcinoma (more urine stasis) - Renal carcinoid
51
I-131 energy and half life
Energy: 365 keV half life: 8 days
52
Gallium 67 half-life and energy
1/2 life: 78 hours Energies: 90, 190, 290, 390 keV
53
When is Tc-99 HMPAO used instead of In-111 WBC for infection?
Kids - Tc-99 has lower absorbed dose and shorter imaging time Small parts - better in hands and feet
54
Biologic half life of Tc-99 MAA?
4 hours
55
Biologic and physical half life of Xenon-133
30 seconds, and 5.3 days
56
How big are Tc-99 MAA particles?
10-100 micrometers.
57
Does reducing particle count in V/Q scan reduce dose?
Not necessarily, normal Tc-99 dose can be added to fewer particles.
58
Tracer localizing to RUQ on ventilation portion of V/Q scan?
Hepatic steatosis. Xenon is fat soluble.
59
Which ventilation tracer must you use for quantitative V/Q?
Xenon-133
60
Ga-67 photo peak
4 of them! - 90, 190, 290, 390 - (actually 93, 184, 300, 393)
61
Ga-67 1/2 life
78 hours (about 3 days)
62
How long after Ga-67 administration do you scan?
after 24 hours, otherwise background signal is too high
63
Critical organ for Ga-67?
Colon
64
I-131 energy and half life
364 keV beta particle, t1/2 8 days
65
Iodine trapping vs. organification
I-123, I-131, and Tc-99 all are trapped by the thyroid (iodine analog transported into gland) Only I-123 and I-131 are organified (oxidized by thyroid peroxidase and bound to tyrosyl moiety). Tc-99 washes out.
66
I-123 half life and energy
t1/2: 13.2 hours energy: 160 keV
67
When can you breast feed after I-123, I-131, and Tc-99?
Tc-99: resume in 12-24 hours I-123: resume in 2-3 days I-131: can't breast feed. pump and dump.
68
Normal thyroid uptake levels?
6-18% at 4-6 hours, 10-30% at 24 hours.
69
Medications affecting thyroid uptake study
- Thyroid blockers (PTU, Methimazole), stop 3 days before test - Nitrates, stop 1 week before test - synthroid, stop 3-4 weeks before test - IV contrast, not within 1 month - Amiodarone, stop 3-6 months before test
70
Viral prodrome with thyroid uptake scan showing decreased %RAIU
de Quervain's thyroiditis (granulomatous thyroiditis)
71
Thyroid nodule HOT on Tc-99 scan, COLD on I-123 scan?
"Discordant" nodule. Concerning for cancer, as some cancers maintain ability to trap iodine analogues (Tc-99m) but lose ability to organify (I-123/131).
72
From what segment of the internal carotid artery does the Inferolateral trunk (ILT) arise?
C4 (cavernous segment)
73
What are the segments of the ICA?
- C1: cervical - C2: petrous - C3: lacerum - C4: cavernous - C5: clinoid - C6: ophthalmic - C7: communicating
74
Threshold for cataract formation from an acute exposure? (20 years after the exposure)
0.5 Gy (50 rads)
75
Which cranial nerve passes under the "eagle's beak" of the jugular tubercle?
CN 12 - hypoglossal nerve. The hypoglossal canal is separated from the jugular foramen by the "eagle's beak".
76
What structure separates the sublingual space from the submandibular space?
Mylohyoid muscle
77
Which Charcot joint site tends NOT to retain normal bone density for age?
Foot, because nearly always associated with diabetes and osteopenic. Shoulder, knee, hip tend to retain normal density for age.
78
Potential causes of PRES?
Big one is hypertension (or labile BP) - post partum - eclampsia/pre-eclampsia - acute glomerulonephritis HUS TTP SLE Drug toxicity Bone marrow transplantation Sepsis
79
Thyroid taking up Tc-99, but not iodine on 24 hour imaging. What gives?
Could be 2 things: 1. Congenital enzyme deficiency preventing organification 2. Medication like PTU that blocks organification
80
Blunt cerebrovascular trauma grading?
Biffl scale: 1: Mild injury, intimal irregularity 2: dissection with raised intimal flap / intramural haematoma with luminal narrowing \>25% / intraluminal thrombosis 3: pseudoaneurysm 4: vessel occlusion/thrombosis 5: vessel transection
81
Longitudinal vs. transverse oriented temporal bone fractures?
Longitudinal more common - less vascular injury - less likely to have facial nerve paralysis (20%) - more likely to have conductive hearing loss vs sensorineural Transverse (20-30% of fractures) -- "Transverse is worse" - more vascular injury - more sensorineural vs conductive hearing loss (disruption of vestibulocochlear nerve) - more facial nerve injury/paralysis (\> 30%)
82
Things that make you resistant to I-131 treatment?
- Medullary subtype cancer (doesn't take up tracer well) - Prior treatment (only more resistant tumor cells left, typically increase dose by 50% for repeat treatment) - Hx of methimazole tx (even years ago)
83
Syndromic associations with medullary thyroid cancer?
- MEN 2 (a and b subtypes) - Von Hippel Lindau - Neurofibromatosis 1
84
When do patients need to be admitted after I-131 tx?
- NRC limit 7 (some states 5) mrem/h measured at 1 meter from patient's chest - effective dose to adult caregivers and family members \< 5 mrem/hr (0.05 mSv/hr) - \< 33 mCi residual activity
85
How long after I-131 treatment do you have to wait before getting pregnant?
At least 6 months
86
Absolute contraindications to I-131 tx?
- Severe uncontrolled thyrotoxicosis - Pregnancy
87
How do you deal with I-131 tx in a dialysis pt?
- Get treatment right after dialysis so tracer sticks around longer - Dialysate goes down drain, TUBING must stay in storage
88
I-131 dosing for cancer ablation?
Low risk: tumor \< 1.5 cm, contained in thyroid - low dose \< 30 mCi High risk: tumor \> 1.5 cm, vessel, lymphatic or capsule invasion, mets, multifocal - high dose 100-200 mCi (Mettler) - 100 for thyroid only, 150 for thyroid + nodes, 200 for distant mets (Crack the Core)
89
Wolff-Chaikoff Effect
Suppression of thyroid function after ingestion of a large amount of iodine - lasts around 10 days - can be used to suppress thyroid in thyroid storm by infusing iodine
90
In-111 photopeak(s)?
170, 250 keV
91
TI-201 photo peak(s)
70, 80 keV (actually 69, 81 keV)
92
Gorlin syndrome?
AKA Basal cell nevus syndrome - Basal cell skin cancer - Medulloblastoma - Dural calcs - Odontogenic cysts
93
What tumor classically arises from the roof of the fourth ventricle? The floor?
Roof: Medulloblastoma Floor: Ependymoma
94
What is TI-201's physiologic mechanism?
Potassium analog - enters cell via Na/K pump. Marker of viability - taken up in living cells w/ functioning Na/K pump, not necrosis or bacteria.
95
CNS perfusion tracers
Tc-99 HMPAO or Tc-99 ECD
96
Hot nose sign on nucs perfusion scan?
Sign of brain death - perfusion stops at skull base for ICAs. More flow to ECA (including face/nose).
97
Nucs study for TIA
Give Diamox (acetazolamide) before perfusion tracer. Areas at risk for ischemia can't dilate any more and will be relatively photopenic.
98
Cingulate island sign
Seen in Lewy body dementia. Low uptake in the lateral occipital lobes with sparing of the posterior cingulate gyrus on FDG-PET brain scan.
99
Signs of NPH on CSF flow nucs study?
- Early entry of tracer into lateral vents (4-6 hours) - Persistent tracer in lateral vents at 24 hours - Delay in ascent to the parasagittal region (\> 24 hours)
100
Nucs CSF flow study tracer?
In-111 DTPA
101
What makes a CSF leak study positive?
- Localized tracer in the sinuses or ears or whatever (abnormal location) on 1-3 hour imaging - Image pledgets that were in the pts nose, if ratio of pledget to serum activity is \> 1.5, that's also positive
102
Shunt patency tracer?
Tc-99 DTPA (can also use In-111 DTPA)
103
Bleeding rate needed for positive tagged RBC vs angio?
Tagged RBC: 0.1 ml/min Angio: 1.0 ml/min
104
Tagged RBC scan with activity over LUQ, salivary glands, thyroid. Positive?
NO - activity over LUQ likely gastric uptake from free Tc. Activity in salivary glands and thyroid confirms.
105
Drugs to enhance Meckel scan?
Pentagastrin - enhances gastric uptake of pertechnetate, stimulates GI activity H2 blockers - block secretion of pertechnetate from gastric cells Glucagon - slow gastric motility
106
Medications that can mimic biliary obstruction on HIDA?
Dilantin (chlorpromazine) and OCPs. Can cause prompt liver uptake and delayed clearance, mimicking CBD obstruction.
107
What do you do before HIDA in neonatal setting?
Give phenobarb to ramp up hepatocyte function
108
Diffuse pulmonary uptake on Tc-99 sulfur colloid scan?
- Most commonly diffuse liver disease - Excess aluminum in colloid - Primary pulmonary issues (phagocytosis by pulmonary macrophages)
109
Bilateral fusiform thickening of the Achilles?
Xanthoma - familial hypercholesterolemia
110
Ball like tumor in extremity of young child?
Synovial sarcoma - Ca++ - Bone erosions - "Never" involve joint - Painful
111
Jaffe-Campanacci syndrome?
- Multiple NOFs - Cafe-au-lait spots - mental retardation - hypogonadism - cardiac malformations
112
Intertrochanteric lesion ddx?
- Lipoma - Liposclerosing myxofibrous tumor (10% undergo malig transformation) - Solitary bone cyst - Monostotic fibrous dysplasia
113
POEMS syndrome?
- Polyneuropathy - Organomegaly - Endocrinopathy - Myeloma - Skin changes, sclerotic bone lesions
114
Syndrome associated with increased radiation sensitivity?
Ataxia telangiectasia
115
Aggressive bone mass with sequestration and associated soft tissue mass?
Primary osseous lymphoma
116
Correct kvP for mammography?
26-33 (30)?
117
Renal scan tracers, mechanism and doses?
Tc-99 MAG3: - Secreted, estimates renal plasma flow (ERPF) - 10-20 mCi - Good for suspected obstruction, poor renal function Tc-99 DTPA: - Filtered, estimates GFR - 10-20 mCi Tc-99 DMSA: - Cortical agent - 5-10 mCi (hangs around in kidneys a long time. Critical organ is kidney, whereas for all others is bladder) - preferred in peds b/c lower dose to gonads (even though higher in kidneys) Tc-99 glucoheptonate: - Cortical agent - 10-20 mCi
118
For nucs renal scan, normal 20/3 and 20/peak ratio?
This is counts at 20 mins over counts at 3 min (or peak) 20/3: normal \< 0.8 20/peak: normal \< 0.3
119
Difference between ATN, Cyclosporin Toxicity, and Acute rejection on MAG3?
ATN and Cyclosporin toxicity both show NORMAL perfusion and DELAYED excretion. - Difference is ATN is 3-4 days post-op and toxicity is later/long standing. Acute rejection is immediately post-op, but shows DECREASED perfusion and delayed excretion.
120
Preferred renal cortical tracer in peds?
Tc-99 DMSA (rather than Tc-99 glucoheptonate)
121
Lipomatous hypertrophy of the interatrial septum vs atrial lipoma
Lipomatous hypertrophy spares the fossa ovalis
122
What transporter does FDG use to enter the cell? Then what happens?
- GLUT-1 - FDG is then phosphorylated by hexokinase to FDG-6-phosphate, locking it in the cell
123
18-FDG critical organ?
Bladder
124
Tumors COLD on PET?
- lung adeno in situ (BAC) - carcinoid - RCC - peritoneal, bowel, liver implants - mucinous tumors - prostate
125
Will a fatter person have higher or lower SUV values on PET?
HIGHER, because fat takes up less glucose (than muscle presumably?) and so more available tracer.
126
Seminomatous vs non-seminomatous GCT on PET?
Seminoma tends to be hot, non-seminomas tend to be cold
127
What medications interfere with MIBG?
- calcium channel blockers - labetalol (other beta blockers ok) - reserpine - sympathomimetics - TCAs
128
What particle size do you use for lymphoscintigraphy (sentinel node detection)?
\<0.2 microns (\<200 nm)
129
How do you tell difference between scar and hibernating myocardium?
Hibernating myocardium will take up FDG and thallium (on delayed imaging)
130
Rb-82 half life?
75 seconds
131
Two most common primaries with mets to kidney?
Lung and breast
132
"Nodule in nodule" on liver MRI?
Appearance of dysplastic nodule with a portion transformed to HCC. Part of the nodule will behave like dysplastic nodule (T1 bright, T2 dark, iso w/ gad), and a smaller part behaves like HCC (++ arterial enh, rapid washout)
133
What tumor marker is elevated in mucinous cystic neoplasms of the pancreas?
CEA \> 400
134
How to differentiate mesenteric carcinoid from fibrosing mesenteritis?
Octreotide scan, will be hot with carcinoid.
135
What is PHACES syndrome?
Posterior fossa (Dandy Walker) Hemangiomas Arterial anomalies Coarctation, Cardiac defects Eye abnormalities Subglottic hemangiomas
136
Hurst disease?
Acute Hemorrhagic Leukoencephalitis Fulminant ADEM with massive swelling and death. Don't see hemorrhage on imaging.
137
Disseminated necrotizing leukoencephalopathy?
Severe white matter changes with ring enhancement. Seen in leukemia patients undergoing chemorads.
138
Binswanger disease?
Subcortical leukoencephalopathy
139
Cingulate island sign?
Seen on brain FDG-PET in Lewy body dementia. Relative photopenia in the occipital region with sparing of the posterior cingulate gyrus.
140
Pseudotumor cerebri associated conditions?
- Hypothyroid - Cushings - Vitamin A toxicity
141
What is MELAS?
Mitochondrial Encephalopathy with Lactic Acidosis and Stroke like episodes
142
CHARGE syndrome?
Coloboma Heart defects Atresia of the choanae Retardation of growth Genitourinary anomalies Ear abnormalities
143
Choanal atresia syndrome associations?
- CHARGE - Crouzon's - DiGeorge - Treacher Collins - Fetal Alcohol Syndrome
144
Cleidocranial dysostosis?
- Brachycephaly (craniosynostosis of coronal or lambdoid sutures) - Wormian bones - Absent clavicles
145
Crouzon's syndrome?
- Brachycephaly - 1st arch hypolasia (maxilla and mandible) - choanal atresia
146
Apert syndrome
- brachycephaly (coronal or lambdoid craniosynostosis) - fused fingers
147
Joubert syndrome?
- molar tooth configuration of superior cerebellar peduncles - vermian hypoplasia or aplasia - retinal dysplasia (50%) - multicystic dysplastic kidney (30%)
148
Meckel-Gruber syndrome
- holoprosencephaly - multiple renal cysts - polydactyly
149
Things associated with schizencephaly?
- optic nerve hypoplasia (30%) - absent septum pellucidum (70%) - epilepsy (50-80%)
150
Gorlin syndrome
Basal cell nevus syndrome - multiple basal cell carcinomas - dural calcs - odotogenic cysts - medulloblastoma
151
Medulloblastoma syndromic associations?
- Turcots syndrome - Gorlin syndrome (basal cell nevus syndrome)
152
Turcot syndrome
- GI polyposis - medulloblastoma - glioblastoma multiforme
153
Lhermitte-Duclos
- dysplastic cerebellar gangliocytoma (hamartoma) - "tiger stripe" appearance - cowden's syndrome - breast cancer (30-50%) - follicular thyroid cancer (5%)
154
Nucs scan to distinguish schwannoma from paraganglioma?
In-111 octreotide - uptake in paraganglioma but not schwannoma
155
Most common bacteria in Lemierre's syndrome?
Fusobacterium necrophorum
156
Significance of fossa of Rosenmuller?
Earliest sign of nasopharyngeal SCC can be effacement of fat in this fossa.
157
Coat's disease
Retinal telangiectasia - subretinal exudate leading to retinal detachment - young boys, unilateral - non-calcified (retinoblastoma will be) - small globe
158
What is VACTERL?
Vertebral anomalies Anal atresia Cardiac anomalies TracheoEsophageal fistula Renal and radial anomalies Limb defects
159
Caudal regression associations?
- Currarino triad - VACTERL - Maternal diabetes
160
McCune Albright vs Mazabraud syndrome?
Both are polyostotic fibrous dysplasia syndromes McCune Albright: - polyostotic FD - cafe au lait spots - precocious puberty Mazabraud: - polyostotic FD - soft tissue myxomas
161
Spinal infections that classically spare the disc space?
- TB - Brucellosis (favors lower L-spine and SI joints) - Aspergillus
162
Subacute combined degeneration?
Vitamin B-12 deficiency - "Inverted V sign" in spine, lesions affecting the bilateral dorsal columns
163
Thickened, enhancing, "onion-bulb" nerve roots in the cauda equina?
- CIDP (Chronic Inflammatory Demyelinating Polyneuropathy) - Charcot Marie Tooth
164
Syndrome associated with choroid plexus carcinoma?
Li-Fraumeni (bad p53 tumor suppressor gene)
165
What mass is a mimic of meningioma?
Hemangiopericytoma - soft tissue sarcoma - enhances homogeneously - No hyperostosis or calcification - invades skull
166
Genetic marker for oligodendroglioma?
1p/19q deletion portends better outcome
167
Differences between TB meningitis and neurosarcoid?
Both will cause basilar meningitis and leptomeningeal enhancement TB: - dystrophic calcs - nodularity - obstructive hydrocephalus - can cause infarct in children Sarcoid: - no hydro
168
What nucs study helps distinguish toxo from lymphoma in the CNS?
Thallium - will be hot in lymphoma, not in toxo.
169
Signs of CNS CMV infection in neonates?
- periventricular calcification - polymicrogyria
170
What disease causes hippocampal atrophy?
Alzheimers
171
What passes through the optic canal?
- CN2 - opthalmic artery
172
What passes through the hypoglossal canal?
Hypoglossal nerve (CN12)
173
What traverses the jugular foramen?
Pars vascularis: - Jugular vein - CNs 10 & 11 (vagus, spinal accessory) - posterior meningeal branch of ascending pharyngeal artery Pars nervosa: - CN 9 (glossopharyngeal) - inferior petrosal sinus venous return
174
What traverses the foramen spinosum?
Middle meningeal artery
175
What traverses the foramen rotundum?
CN V2 "R2V2"
176
What traverses the superior orbital fissure?
CNs V1, 3, 4, 6
177
What traverses the foramen ovale?
CN V3, accessory meningeal artery
178
Types of mediastinal germ cell tumors?
Teratoma: cystic, fat and calcium Seminoma: bulky and lobulated, "straddles the midline" Non-seminomatous GCT: big and ugly, hemorrhage, necrosis. Can invade lung
179
Most common cause of unilateral lymphangitic carcinomatosis?
Lung adeno invading lymphatics.
180
What nucs study would you use to localize a carcinoid tumor?
Octreoscan
181
Which is more common in the trachea, carcinoid or adenoid cystic?
Adenoid cystic
182
What virus is associated with PTLD and when does it generally occur with respect to transplant?
Epstein Barr virus, and usually within 1 year of transplant
183
Two most common lung tumors in AIDS patients?
1. Kaposi 2. AIDS related pulmonary lymphoma (usually high grade NHL)
184
Size criteria for treating pulmonary AVM?
Afferent vessel \> 3mm
185
What is Swyer-James?
Classic cause of unilateral lucent lung (Poland syndrome is another). Post-viral obliterative bronchiolitis. Affected lobe is small.
186
Omphalocele vs gastroschisis?
Omphalocele: - midline - covered by peritoneum and amnion ("omphalosealed") - trisomy 18 most common associated chromosomal anomaly (though also associated with trisomy 13, Turners, Downs, Klinefelters, Beckwith-Widemann, pentalogy of Cantrell) - lots of other associated abnormalities (CNS, cardiac, bladder exstrophy - elevated maternal AFP Gastroschisis: - always right sided - NOT covered by membrane - not many associated abnormalities, except for GI stuff like malro, stenosis or atresia. - even more elevated maternal AFP
187
Associations with extralobar sequestration?
Presents in infancy with respiratory distress, usually because of the associated anomalies: - CPAM - congenital diaphragmatic hernia - vertebral anomalies - congenital heart disease - pulmonary hypoplasia
188
Malignancies associated with CPAM?
Pleuropulmonary blastoma, rhabdomyosarcoma
189
Lymphangioleiomyomatosis associations?
- Tuberous sclerosis - Renal AMLs - chylothorax - strongly favors women
190
Birt Hogg Dube?
- Oval shaped lung cysts - Oncocytomas - Chromophobe RCCs
191
Lymphocytic Interstitial Pneumonia associations?
- Autoimmune diseases (SLE, RA, Sjogrens) - Sjogrens in 25% of LIP cases - HIV (LIP in a younger patient, like children - apparently LIP in HIV pos adults is rare) - Castleman disease
192
Saber sheath trachea?
Diffuse tracheal narrowing in the transverse dimension, sparing the extrathoracic portion. Means the patient has COPD.
193
What is compensatory emphysema?
AKA Postpneumonectomy syndrome, where you've taken out one lung so the other hyperinflates to compensate. Not an obstructive process like regular emphysema.
194
Earliest pleural manifestation of asbestos exposure?
Benign pleural effusion. Lag time about 5 years after exposure.
195
What do you worry about with cavitation in the setting of pulmonary silicosis?
TB. Silicosis increases risk of TB by about 3x.
196
What lung disease is associated with scleroderma?
NSIP
197
Most common recurrent primary disease after lung transplant?
Sarcoidosis (35%)
198
Long segment subglottic circumferential tracheal thickening without calcs?
Wegener's. Can be focal or long segment. Commonly involves the subglottic trachea and involves the posterior membrane.
199
Which tracheal pathologies spare the posterior membrane?
TBOP: Tracheobronchopathia osteochondroplastica - cartilaginous and osseous nodules in the submucosa of the trachea and bronchi Relapsing polychondritis: diffuse thickening of the trachea, but NO calcification. Get recurrent cartilage inflammation elsewhere (like the ear) and also recurrent pneumonia
200
Favored locations of tracheal squamous cell vs adenoid cystic?
SCC is most common tracheal tumor and favors the lower trachea and proximal bronchus, adenoid cystic favors the upper trachea.
201
Syndrome with congenital cystic bronchiectasis?
Williams Campbell syndrome. Deficiency of cartilage in the 4-6th order bronchi
202
Syndrome with massive dilation of the trachea?
Mournier-Kuhn (Tracheobronchomegaly). Trachea dilated \> 3 cm.
203
Hepatopulmonary syndrome?
Cirrhotic patient - develop subpleural telangiectasias which engorge and shunt blood when the patient sits up. Therefore they get the opposite of CHF symptoms, i.e. shortness of breath when sitting up.
204
What extrathoracic effects can a fibrous tumor of the pleura cause?
- hypertrophic pulmonary osteoarthropathy - hypoglycemia
205
Empyema necessitans causative organisms?
Empyema nananananananana BATMAN! Blastomycosis Actinomycosis (2nd most common) Tuberculosis (most common, 70%) Mucormycosis Aspergillosis Nocardia
206
Most common side for traumatic diaphragmatic hernia?
Left side, since on the right the liver acts as a protector of the diaphragm.
207
When is a superior sulcus tumor unresectable?
- brachial plexus involvement above T1 (C8 or higher) - diaphragm paralysis (involvement of C3,4,5) - greater than 50% vertebral body - distal nodes or mets
208
Classic location for pericardial cyst?
Right anterior cardiophrenic angle
209
Classic cause of fibrosing mediastinitis?
Histoplasmosis. Most common cause is actually idiopathic. - Can also be caused by radiation, TB, and sarcoid. - can calcify - can cause SVC syndrome - when idiopathic, associated with retroperitoneal fibrosis (IgG-4 related disease)
210
What is a Rasmussen aneurysm?
Pulmonary artery pseudoaneurysm secondary to TB
211
What pulmonary artery pressure defines hypertension?
\> 25 mmHg
212
In what time frame should a pulmonary contusion resolve?
By 72 hours - if it doesn't resolve by then, it's probably aspiration/pneumonia or laceration.
213
Most common locations for aortic injury?
1st: Aortic isthmus (90%, just distal to left subclavian. site of ligamentum arteriosum) 2nd: aortic root 3rd: diaphragm
214
Bosniak criteria?
1: simple cyst (0% risk) 2: \< 3cm, hyperdense, thin septations and calcium (0% risk) 2F: \> 3cm, hyperdense, this septations and calcium (5% risk, ? 6 mo f/u) 3: Thick septations and calcium, mural nodule (50% risk, partial nephrectomy or RF ablation) 4: Any enhancement (100% risk, partial or total nephrectomy)
215
Renal insufficiency, hx of bipolar disorder
Lithium nephropathy - innumerable small cysts - diabetes insipidus
216
Medullary nephrocalcinosis causes?
- hyper PTH - medullary sponge kidney (usually asymptomatic) - lasix use in a child - distal (type 1) RTA
217
Most common congenital anomaly of the GU tract?
UPJ obstruction - associated with crossing vessels - associated with contralateral multicystic dysplastic kidney
218
Ureteral wall calcs?
- Schistosomiasis (increased risk of SCC) - TB
219
Ureteritis cystica?
Tiny subepithelial cysts in ureteral wall - project into lumen and cause filling defects - from chronic inflammation (stones, infx) - diabetics with recurrent UTI - ? inc risk of cancer
220
Malacoplakia vs leukoplakia?
Leukoplakia: - squamous metaplasia from chronic irritation/inflammation - mural filling defects - PREMALIGNANT Malacoplakia: - assoc with E. coli infx, plaques are masses of bacteria - female immunocompromised pts - NOT premalignant - tx with antibiotics - assoc with obstruction
221
Balkan nephropathy?
Degenerative nephropathy secondary to ingestion of aristolochia clematitis seeds - very increased risk of renal pelvis and upper ureter TCC
222
What increases your risk of SCC of the urinary tract?
Schistosomiasis infection. Also causes calcification.
223
"Bunch of grapes" mass protruding from vagina?
Sarcoma botryoides or botryoid variant of rhabdomyosarcoma - occurs in hollow, mucosa lined structures, i.e. nasopharynx, bladder, vagina
224
When do you get adenocarcinoma of the bladder?
Cancer of a urachal remnant. Therefore will be centered at the midline bladder dome.
225
Urethral cancer types and where they occur?
- Mostly SCC (80%) - If in prostatic segment, more likely TCC (90%) - If in urethral diverticulum, adenocarcinoma
226
Struma ovarii?
Teratoma subtype of the ovary containing thyroid tissue - multilocular cystic mass - intensely enhancing solid component - LOW signal on T2 in cystic appearing areas due to colloid
227
Ovarian vein thrombophlebitis clinical setting and sidedness?
Postpartum women - acute pelvic pain and fever - increased risk with c-section, endometritis Right sided 80%
228
Posterior urethral cysts?
Prostatic utricle cyst - prune belly, Downs, unilat renal agenesis - imperforate anus Mullerian duct cyst - mullerian duct remnant, can get endometrial, clear cell or squamous cancers Seminal vesicle cyst - unilateral lateral cyst. renal agenesis, vas agenesis, ectopic ureter, PCKD
229
Antibody seen in PBC?
Antimitochondrial antibody
230
What is peliosis?
Blood filled cystic spaces in a solid organ (usually liver) - Idiopathic, but associated with OCPs, steroids, AIDS, renal tx, Hodgkins lymphoma
231
What organism causes AIDS cholangiopathy classically?
Cryptosporidium infection of biliary epithelium - 60% get papillary stenosis - intra and extrahepatic strictures
232
Things that increase risk for GI lymphoma?
- SLE - AIDS - Celiac - Crohn's
233
Rectal cancer stage that requires chemorads prior to surgery?
T3: invasion of perirectal fat
234
How energetic must a photon be to eject an electron (in eV)?
15 eV. Photons with at least 15 electron volts energy is considered "ionizing radiation"
235
Why is Rhenium sometimes mixed in with Tungsten in the x-ray filament?
Helps prevent tungsten from cracking after many heat/cool cycles
236
How much increase in mA will double beam intensity? How about for kVp?
Doubling mA will double intensity, while increasing kVp by 15% doubles intensity.
237
How does the average energy relate to kVp (approximately)?
Average energy is between 1/3 - 1/2 of the kVp
238
Which contributes to image blur, actual or apparent focal spot?
Apparent focal spot, the focal spot on the patient.
239
Does heel effect increase or decrease with increased source to image distance?
Decrease
240
Does heel effect increase or decrease with increased field size?
Increase
241
Does heel effect increase or decrease with increased anode angle?
Decrease
242
What is the approximate energy (keV) that divides primarily compton vs. photoelectric interactions?
30 keV
243
As linear attenuation coefficient increases, what happens to half value layer?
Decreases. Inverse relationship according to Crack video
244
What substance is used in the detector cassette in CR?
Barium fluorohalide
245
Indirect vs direct DR?
Indirect: - uses cesium iodide as a phosphor, generates visible light photos which disperse a little before hitting a photodiode which translates image to electrical signal Direct: - uses amorphous selenium to directly transfer x-ray photons to electrical signal. No lateral dispersion affecting resolution like in indirect system.
246
What is DQE (detector quantum efficiency) and is it better for DR or CR?
DQE is the ratio of signal coming in to detector (radiation) vs signal in resulting image. 1.0 would be perfect. DR is about 0.5 (0.45), and CR is worse at about 0.25.
247
What percent of bone mineralization must be lost to be detectable on plain radiograph?
30-40%
248
What is the ratio of gadolinium to saline for arthrogram injection?
0.1 mL gad to 20 mL saline/anesthetic
249
Reducible ulnar deviation at the MCPs with preserved joint spaces?
SLE or Jaccoud Jaccoud is ligamentous laxity with a history of rheumatic fever
250
Focal spot size for regular mammogram vs mag view?
Regular mammogram = 0.3 mm Mag view = 0.1 mm
251
What effect will increasing kVp and mA have on quantum mottle?
Increasing kVp or mA will both DECREASE mottle
252
Iodine k-edge?
33.2 keV
253
How does source to patient distance affect KAP/DAP (kerma/dose area product)?
It doesn't. The KAP is independent of the source location
254
Classic differential for leptomeningeal carcinomatosis?
MOCLEGG or GEMCLOG - Medulloblastoma - Oligodendroglioma - Choroid plexus tumor - Lymphoma - Ependymoma - Glioblastoma - Germinoma
255
How is target heart rate calculated for cardiac stress test?
Target HR = 85% maximal HR Maximal HR = 220 - age
256
When is the 180 deg rephasing pulse done in a spin echo sequence?
1/2 TE
257
Which tracers decay by electron capture?
GIIT Gallium, Indium, I-123, Thallium
258
Thin vs thick scintillation crystal?
Sodium iodide crystal doped with thallium - thin crystal increases spatial resolution but decreases sensitivity - thick crystal decreases spatial resolution but decreases sensitivity
259
Equation for effective half life?
1/Te = 1/Tp + 1/Tb Te = effective 1/2 life Tp = physical 1/2 life Tb = biologic 1/2 life
260
How long do you keep radioactive material before it's safe to discard?
10 half lives
261
Limit for aluminum contamination of Tc-99?
\< 10 micrograms per 1 ml
262
Limit for free Tc in a dose?
Most of the time, must be at least 90% bound Tc-99. Between 90-95% depending on what it's being bound to.
263
Is testing for chemical purity mandated in NRC states?
No.
264
What type of equilibrium is a Tc/Mo generator?
Transient equilibrium
265
Hand and thumb defects with an ASD?
Holt Oram
266
What other anomaly is strongly associated with unroofed coronary sinus?
Persistent left SVC
267
What type of TAPVR causes pulmonary edema appearance in the newborn?
Type 3, infracardiac. Pulmonary veins drain below the diaphragm, and can be obstructed by the diaphragm causing edema.
268
Differential for lucent metaphyseal lines in a child?
- Leukemia, lymphoma - Severe illness - TORCH infx - Scurvy
269
Most common intraorbital, extraocular tumor in children?
Rhabdomyosarcoma
270
Most common intraorbital tumor in children?
Retinoblastoma
271
What proportion of schizencephaly are bilateral?
Up to half. About 2/3 are open lip. (A little less often when bilateral - about 60%)
272
Differential for diffusely dense bones in a child?
Osteopetrosis Pyknodysostosis Hypervitaminosis A Renal osteodystrophy Fluorosis
273
What is the age group for choroid plexus papilloma/carcinoma?
Children less than 5 An intraventricular enhancing mass in the atrium in an older child, maybe teen, more likely to be meningioma)
274
Cardiac defect most commonly associated with aortic coarctation?
Bicuspid aortic valve (80%)
275
Grade viability of myocardium on MRI?
Based on % thickness involved in infarct: \< 25%: likely to improve with PCI 25 - 50%: may improve 50 - 100%: unlikely to recover function
276
In cardiac amyloidosis, is the TI generally longer or shorter than normal?
Longer. Difficult to suppress myocardium. TI may be so long that blood pool is darker than myocardium.
277
Waterhouse-Freidrichsen syndrome?
Acute adrenal hemorrhage in the setting of fulminant meningitis. Causative organism: Neisseria meningitidis.
278
Dilated RV with reduced wall motion and fatty replacement of the myocardium?
Arrhythmogenic Right Ventricular Dysplasia (ARVD)
279
Non-compaction ratio and when to measure?
Ratio: \>2.3 : 1 non-compacted : compacted myocardium When to measure: end-diastole
280
Kid with dilated cardiomyopathy and midwall delayed enhancement?
Muscular dystrophy: Becker (mild) or Duchenne (severe) Biventricular replacement of myocardium with connective tissue and fat X-linked
281
Smoothly marginated T1/T2 dark cardiac mass with central calcification?
Cardiac fibroma. Higher incidence in Gorlin syndrome
282
What is the first branch of the SMA?
Inferior pancreaticoduodenal artery
283
Branches of the posterior division of the internal iliac artery?
I Love Sex: - Iliolumbar - Lateral Sacral - Superior Gluteal
284
Winslow pathway?
Collateral arterial pathway connecting aorta to iliacs via subclavian -\> internal thoracic (mammary) -\> superior epigastric -\> inferior epigastric -\> iliac. Becomes important in aorto-iliac occlusive disease. Can be disrupted in transverse incision abdominal surgery.
285
When does the subclavian artery become the axillary artery? The brachial?
Subclavian becomes axillary at the first rib. Axillary becomes brachial at the lower border of the teres major.
286
What structure marks the point where the external iliac becomes common femoral?
The inferior epigastric origin.
287
In a circumaortic left renal vein, which limb is superior?
The anterior limb (anterior to the aorta) is superior, the posterior limb is inferior.
288
Differential for shortening of 4th/5th metacarpals?
- Turner syndrome - Pseudohypoparathyroidism (also pseudopseudohyperPTH) - Basal cell nevus syndrome (Gorlin) - Sickle cell disease - Hereditary multiple exostosis syndrome - Homocystinuria - Post-infectious - Post-traumatic - Idiopathic
289
Floating viscera sign?
Classic angiographic sign of abdominal aortic dissection. Aortic branch arteries appear to arise out of nowhere, unopacified false lumen adjacent to artery origin. http://www.annalscts.com/article/viewFile/1696/2373/6588
290
Most common underlying causes for acute aortic syndromes?
Dissection and intramural hematoma: Hypertension. Penetrating ulcer: Severe atherosclerosis.
291
Leriche syndrome?
Occlusion of the aorta distal to the renal arteries (usually at the bifurcation). Secondary to bad athero usually. Triad: - Butt claudication - Absent/decreased femoral pulses - Impotence
292
Triad of HTN, claudication, and renal failure?
Mid aortic syndrome. Progressive narrowing of abdominal aorta and major branches. - Different from Leriche in that it is longer segment and higher. - Affects children and young adults
293
Hughes-Stovin syndrome?
Rare variant of Behcet's disease, characterized by pulmonary artery aneurysm formation/rupture, and recurrent thrombophlebitis.
294
Rasmussen aneurysm?
Pulmonary artery pseudoaneurysm secondary to pulmonary TB (associated with cavitary lesion). Usually upper lobes.
295
In median arcuate ligament syndrome, does it get better or worse with expiration?
Worse with expiration, better with inspiration.
296
Association with popliteal artery aneurysm?
Abdominal aortic aneurysm (30-50%) 10% of people with AAAs have popliteal aneurysm 50-70% of popliteal aneurysms are bilateral Biggest concern: distal embolization of thrombus from aneurysm causing acute limb ischemia.
297
Ankle-brachial index ranges?
1.0 = normal 0.3 - 0.5 = claudication \< 0.3 = rest pain
298
Cogan syndrome?
Large vessel vasculitis affecting children and young adults. Eye and ear involvement with optic neuritis, uveitis, and meniere-like disease. Also can get aortitis, which portends worse prognosis.
299
Short differential for microaneurysm formation in the kidney?
- Polyarteritis nodosa - Speed kidney (crystal meth use)
300
Erosion of nasal septum, saddle nose deformity? No drug history.
Granulomatosis with polyangiitis (Wegener's)
301
Gradenigo syndrome?
Petrous apicitis with involvement of Dorello canal (CN 6) resulting in lateral gaze palsy.
302
Multiple splanchnic artery saccular aneurysms?
SAM (Segmental Arterial Mediolysis) Not really vasculitis, no inflammation. Media of vessels degenerates --\> aneurysms.
303
Multiple cysts around the popliteal artery with compression?
Cystic Adventitial Disease - affects popliteal artery of young men - multiple mucoid filled cysts develop in the outer media and adventitia, which eventually compress the artery
304
Normal carotid velocity? ICA/CCA ratio? ICA end diastolic velocity??
Normal: Carotid velocity: 125 cm/s ICA/CCA ratio: 2 ICA end diastolic velocity: \< 40 cm/s
305
Unilateral vs bilateral tardus parvus in carotid?
Unilateral - innominate artery stenosis Bilateral - aortic valve stenosis
306
Reversal of diastolic flow in bilateral common carotid arteries?
Aortic regurgitation.
307
Most common biliary ductal variant?
Drainage of the right posterior segment branch into the left hepatic duct (13 - 19%). Normal is the right posterior joining the right anterior to form the right hepatic duct, which then joins the left hepatic. http://goo.gl/ulJHjt Second most common is trifurcation of the right anterior, right posterior, and left hepatic ducts (11%).
308
What are the exceptions to restricted access in zones 3 & 4?
No exceptions! Even if patient is coding, techs should start CPR then move patient out of restricted areas to code team.
309
Epi doses/dilutions for contrast reaction?
IM: 1:1000, 0.1 - 0.3 ml IV: 1:10,000, 1 - 3 ml Both of these give the same dose (0.1 - 0.3 mg), but use smaller volume for injecting into soft tissues.
310
Strontium 89 half life?
50.5 days (14 days in bone)
311
Samarium-153 half life
46 hours
312
Yttrium-90 half life?
64 hours
313
Differences in bone met therapeutic agents?
Sr-89: - pure beta emitter - most marrow toxicity (longest recovery) - renal excretion - t1/2 = 50 days (14 in bone) Sm-153: - beta emitter, with some gamma (imageable) - less marrow toxicity - renal excretion - t1/2 = 46 hours Ra-223: - alpha emitter - least marrow toxicity - GI excretion - t1/2= 11.4 days - shown to improve survival with metastatic prostate CA
314
Valve at the end of the coronary sinus where it drains into the RA?
Thebesian valve
315
What is the most common vascular ring?
Double aortic arch - right arch usually larger and more superior
316
What is the only vascular cause of stridor in a pt with a left arch?
Pulmonary sling
317
Syndrome associated with cardiac rhabdomyoma?
Tuberous sclerosis.
318
What is the earliest sign of tuberous sclerosis that can be diagnosed in utero?
Cardiac rhabdomyoma.
319
Medial apophysitis of the elbow?
Little leaguer's elbow AKA medial apophysitis or epiphysiolysis. Marrow edema on MR within the medial humeral epicondyle. May see osteopenia on X-ray, widening or late closure of the physis.
320
Where does the biceps tendon attach?
Radial tuberosity
321
What MELD score puts you at higher risk for early death after elective TIPS?
MELD \> 18
322
Absolute contraindications for TIPS?
- Severe heart failure (right or left) - Biliary sepsis - Isolated gastric varices (splenic vein occlusion) Relative contraindications: - cavernous transformation of the portal vein - severe hepatic encephalopathy
323
What qualifies as massive hemoptysis?
\> 300 cc in 24 hours
324
What embolic material should you use for massive hemoptysis?
Use particles for bleeding bronchial arteries, so if it rebleeds after treatment you can still get back and treat again. Exception is AVM or aneurysm, where obviously you don't want to use particles, since they'll shunt to systemic circulation and fuck shit up.
325
Contraindications to uterine artery embolization?
- Pregnancy - Active pelvic infection - Prior pelvic radiation - Connective tissue disease - Prior surgery with adhesions (relative contraindication)
326
When do you place an IVC filter above the renal veins?
- Pregnancy (avoid compression) - Clot in renal veins or gonadal veins - Probably clot in previously placed infrarenal IVC filter, though isn't mentioned in Crack
327
Skin changes by fluoro dose?
2 Gy: early transient erythema 6 Gy: chronic erythema 10 Gy: telangiectasia 13 Gy: dry desquamation 18 Gy: moist desquamation
328
"Shrinking breast"?
Invasive lobular breast cancer.
329
Axillary lymph node levels?
1: lateral to pec minor 2: under pec minor 3: medial to pec minor Rotter node: between pec major and minor
330
Risk of malignant degeneration with Phyllodes tumor?
10%. Can metastasize, usually to lungs and bone. Fast growing. Mimics a fibroadenoma. Need wide margin resection, margin \< 2cm assoc with higher recurrence rate.
331
What is the most common pineal mass?
Germinoma
332
Parinaud syndrome is most associated with lesions of what structure?
Pineal gland, compressing the tectal plate. - Upward gaze deficiency - pupillary light-near dissociation (pupils respond to near stimuli but not light) - convergence retraction nystagmus
333
Differential for mass in the anterior half of the lateral ventricle?
- Subependymoma: older male - Ependymoma: young - Subependymal giant cell astrocytoma (near the foramen of Monro): tuberous sclerosis patient - Central Neurocytoma (attached to septum pellucidum): patient in their 20s
334
What subtype of medulloblastoma tends to occur in older patients and more peripherally within the cerebellar hemisphere than classic medulloblastoma?
Desmoplastic/Nodular Medulloblastoma tends to occur in older patients and more peripherally within the cerebellar hemisphere than classic medulloblastoma.
335
What cell do meningiomas arise from?
Arachnoid cap cell
336
There is a fourth ventricular mass in a 58yo man. What is the most likely diagnosis?
Subependymoma. Subependymoma occurs in old patients (5th to 6th decades of life), ependymoma occurs in young patients (major peak 1-5yo, second smaller peak mid 30s).
337
For a CSF shunt study, how is the dose of 99mTechnetium-DTPA administered?
The dose of 99mTechnetium-DTPA is injected by a physician using sterile technique into the CSF shunt reservoir. The shunt reservoir can be palpated as a raised area on the scalp (deep to the skin and superficial to the bone). The patient should be in the supine position during the injection. Immediately after injection, the patient undergoes dynamic imaging at a rate of 1 min/frame in the supine position. For ventriculoatrial shunts, imaging should include the head to the heart, and for ventriculoperitoneal shunts imaging should include the head to the peritoneal cavity.
338
At what point in fetal development should the corpus callosum be fully developed?
20 weeks
339
Which part of the corpus callosum forms last?
Rostrum
340
If CT findings are consistent with acute subarachnoid hemorrhage and CT angiogram is negative, what is the next step?
Catheter cerebral angiogram
341
What artery chiefly supplies the amygdala?
Anterior choroidal artery
342
In Huntingtons disease, Tc-HMPAO imaging classically demonstrates decreased radiotracer uptake involving which structures?
Caudate nuclei
343
What is the acuity and expected MR signal of a 4 day old hemorrhage?
Early subacute, T1 bright, T2 dark. Hyperacute: It Be (0-7 hrs) Acute: Iddy (7-72 hrs) Early subacute: Biddy (72 hrs - 7 days) Late subacute: Baby (7 days - 3 weeks) Chronic: DooDoo (\> 3 weeks)
344
What is the most common type of traumatic intracranial hemorrhage?
Subdural hematoma
345
What conditions give you isolated brachydactyly of the 4th and 5th metacarpals?
- Pseudohypoparathyroidism - Pseudopseudohypoparathyroidism - Turner's syndrome
346
What percent of children who present with meningioma will go on to develop NF2?
Approximately 20%
347
What type of cancer could epidermoids or dermoids in the head degenerate into?
Squamous cell cancer, rarely
348
The most common consequence of ruptured dermoid is?
Chemical meningitis
349
What is associated with poorer outcomes in ependymoma?
- 4th ventricle location - patient \< 2 years old
350
Cowden syndrome is associated with an increased risk of which CNS pathology?
Cowden syndrome, also known as multiple hamartoma syndrome, is an autosomal dominant inherited disorder characterized by multiple hamartomas throughout the body and increased risk of certain cancers. Cowden syndrome is associated with an increased risk of dysplastic gangliocytoma of the cerebellum (also known as Lhermitte-Duclos disease), a WHO Grade I tumor.
351
In patients with chronic liver disease, the basal ganglia may demonstrate which MR signal abnormality compared to normal patients?
Some patients with chronic liver disease may demonstrate characteristic increased T1 signal in the basal ganglia on MRI. Experts have associated this finding with an atypical form of Parkinsonism that occurs in chronic liver disease. Neuropathogically the increased T1 signal reflects manganese accumulation within the globus pallidus. Similar MRI findings have been described in patients receiving long-term parenteral nutrition with excessive manganese content, and the findings resolve with elimination of manganese from the feeds.
352
Hyperattenuating, hyperenhancing mass at anterior 3rd ventricle?
Choroid glioma. Chordoid glioma tends to occur in a very specific place: the anterior wall of third ventricle/hypothalamus. On CT, these lesions classically appear as a well-circumscribed hyperattenuating lesion in the anterior wall of third ventricle and hypothalamus and demonstrate avid contrast enhancement. The lesion is hyperattenuating because it contains a proteinacous fluid, not because of hypercellularity.
353
"Breast within a breast"?
Hamartoma. Difficult to see on US as they blend in.
354
Via which route does phyllodes metastasize?
Hematogenously, to the lungs and bone
355
What are the 5 classic high risk breast lesions?
- Radial scar (associated with Tubular DCIS/IDC 10-30%) - Atypical ductal hyperplasia (30% of time surg path will upgrade to DCIS) - Lobular carcinoma in situ (can be precursor to ILC, but less often than DCIS --\> IDC) - Atypical lobular hyperplasia (milder than LCIS) - Papilloma (most common intraductal mass, most common cause of bloody discharge)
356
Risk factors for male breast cancer
Klinefelters, cirrhosis/chronic alcoholism
357
If you see silicone in an axillary lymph node, does this mean the implant has ruptured?
No. Silicone molecules can apparently pass through the semi-permeable implant shell normally.
358
Breast cancer T staging?
T1: \<2 cm T2: 2 - 5 cm T3: \> 5 cm T4: Any size, with chest wall fixation, skin involvement, or inflammatory CA. Pagets of breast DOES NOT count as T4.
359
Most common tumor to met to the breast?
Melanoma.
360
Nipple enhancement on breast MRI?
Normal - don't call it Pagets
361
On breast MRI, what malignant things could be T2 bright?
Colloid cancer or Mucinous cancer. Everything else T2 bright is generally benign.
362
What is the minimum compressibility of the breast for stereotactic biopsy?
The breast cannot compress to less than 2-3 cm. If it does, you risk going through and through the breast when you fire the biopsy device. If it compresses too small, you should do a wire localization for excisional bx.
363
Required line pair resolution for mammo?
13 lp/mm in the anode/cathode direction 11 lp/mm in the left/right direction
364
How many fibers, masses, and microcalc clusters for mammo QC?
4, 3, 3 4 fibers, 3 masses, 3 microcalc clusters (Four Fibers, three of the others)
365
For mammo, how often do you do processor QC and check darkroom cleanliness?
Daily. Processor QC and darkroom cleanliness: Daily Viewbox conditions and phantom evaluation: Weekly Repeat analysis: Quarterly Compression test, darkroom fog and screen-film contrast: Semi-annually
366
For mammo, how often do you do repeat analysis?
Quarterly. Processor QC and darkroom cleanliness: Daily Viewbox conditions and phantom evaluation: Weekly Repeat analysis: Quarterly Compression test, darkroom fog and screen-film contrast: Semi-annually
367
For mammo, how often do you check compression test, darkroom fog, and screen-film contrast?
Semi-annually. Processor QC and darkroom cleanliness: Daily Viewbox conditions and phantom evaluation: Weekly Repeat analysis: Quarterly Compression test, darkroom fog and screen-film contrast: Semi-annually
368
For mammo, how often do you check viewbox conditions and do phantom evaluation?
Weekly. Processor QC and darkroom cleanliness: Daily Viewbox conditions and phantom evaluation: Weekly Repeat analysis: Quarterly Compression test, darkroom fog and screen-film contrast: Semi-annually
369
For mammo medical audit, what are the target ranges for recall rate and cancers/1000 screened?
Recall rate: 5-7% Cancer/1000 screened: 3-8
370
How could you maintain a constant exposure while lowering dose?
Raise kVp by 15% while lowering mAs by 50%. This will maintain the same exposure, higher energy x-rays will penetrate more easily and deliver less dose.
371
What three things affect heel effect, and how?
- Anode angle: Effect worse with smaller angle - Source to image distance (SID): Worse with smaller distance - Field of view: Worse with larger FOV
372
What percent of GI duplication cysts contain ectopic gastric or pancreatic tissue?
50% - Most are symptomatic - Small bowel more common
373
Earliest sign of NEC on plain film?
Fixed, dilated unfolded loop of bowel.
374
Flux gain vs minification gain?
In an image intensifier, flux gain refers to the increase in magnitude of light from the OUTPUT phosphor due to the voltage applied between the input and output phosphors. This makes the electrons speed up, increasing energy, which is then proportional to the light created on the output phosphor. Minification gain is the concentration of electrons on the output phosphor just because it's smaller. So, more electrons per unit area --\> increased energy/light
375
When are grids not used?
Extremities and peds
376
As you move the source away from the patient, how does dose area product change?
It doesn't change. DAP is independent of beam location. As intensity decreases by inverse square law, area of beam hitting patient increases by same amount. So nothing changes.
377
Max dose rates for High Level Control vs no HLC?
Normal mode: 10 R/min (87 mGy/min) HLC: 20 R/min (176 mGy/min) Audible alarm must be on when HLC is used
378
What happens at different skin doses?
2 Gy: Early transient erythema 3 Gy: Temporary epilation (hair loss) 6 Gy: Chronic erythema / "Main erythema" 7 Gy: Permanent Epilation 10 Gy: Telangiectasia 13 Gy: Dry desquamation 18 Gy: Moist desquamation / Ulceration 24 Gy: Secondary ulceration
379
What is the bit depth of a CT pixel?
12 bits, which equals 4096 possible shades of grey. 2^12 = 4096
380
What generation are most CTs currently?
3rd generation, i.e. fan beam with continuous rotation. See figure here: http://flylib.com/books/1/511/1/html/2/files/02fig38.jpg
381
If you double mAs, how much does the signal to noise ratio increase?
Signal increases proportionally, i.e. 2 x mAs = 2 x signal. Noise increases by factor of sqrt(2), i.e. 2 x mAs = sqrt(2) x noise So, SNR increases by 1.4x when you double mAs (2/sqrt(2) = 1.4)
382
How does slice thickness affect contrast resolution?
Larger slice thickness = more x-ray quanta = less noise. And vice-versa
383
What causes ring artifact on CT?
Calibration error or defective detector.
384
In ultrasound, what is the relationship between probe frequency and attenuation per unit distance?
It's proportional, so a 2 MHz probe will attenuate twice as much over a certain distance as a 1 MHz probe. Hence, poorer penetration for high frequency probes. Also, sound intensity is exponentially attenuated with distance for a given frequency.
385
How does US transducer crystal thickness relate to wavelength?
The transducer is 1/2 the wavelength. Lower frequency probe = thicker crystal.
386
Thin vs thick damping block?
Thin block (light damping): - "Ding" - High quality/narrow bandwidth (more pure frequency spectrum) - Longer spatial pulse length (takes longer to damp crystal vibration) - For doppler, to preserve velocity information (measuring frequency shift, so need a narrower range of frequencies in the beam) Thick block (heavy damping): - "Thud" - Low quality/broad bandwidth (less pure frequency spectrum, more off target frequencies sent out) - Shorter spatial pulse length (quickly dampens crystal vibration) - Higher axial spatial resolution, since the pulse length is short you can resolve things right on top of one another
387
What is the optimal matching layer thickness?
1/4 the wavelength. Crystal thickness is 1/2 the wavelength. Matching layer helps transition from the acoustic impedance of the crystal material to the impedance of the patient tissue, so the matching layer impedance is in between.
388
What effect does adding multiple focal zones have on temporal resolution?
Multiple focal zones decreases temporal resolution. Since each focal zone is a separate set of transducer pulses (send and receive), the frame rate (temporal resolution) goes down.
389
Minimum separation between two reflectors to resolve on US?
1/2 the spatial pulse length. By the time one pulse has traveled the extra 1/2 pulse length distance TO the second reflector, another pulse reflected from the first reflector is 1/2 the pulse length back towards the detector, making them separated by one whole pulse length, hence no overlap and they can be resolved as separate by the transducer. Here's a shitty animation: http://i.imgur.com/E9WVTWo.gifv
390
What type of transducer is more likely to produce side lobe artifact?
Linear array transducer. Produced by radial expansion of PZT crystals. "Pseudosludge" in the gallbladder.
391
What is the Nyquist limit?
1/2 the pulse repetition frequency (PRF). If the doppler frequency shift is larger than this limit, you'll get aliasing. For example, a frequency shift of 3.5 kHz (corresponding to some flow velocity) requires a PRF of 7 kHz to avoid aliasing. How to reduce aliasing? - Reduce magnitude of doppler shift by using a lower freq transducer or increasing the angle closer to 90 deg - Increase PRF (this will increase the Nyquist limit), seems like this is the same as increasing the scale - Select sample volume at lesser depth (less time for echoes to go out and back, so the PRF increases)
392
What is the difference between power and gain in ultrasound?
Increasing power increases penetration depth. Gain just changes the brightness displayed on the monitor, but doesn't do anything to the transducer output.
393
What is the thermal index in ultrasound?
Maximum temperature rise in tissue secondary to energy absorption.
394
What is the mechanical index in ultrasound?
Measure of how likely it is cavitation will occur for a given peak rarefaction pressure and frequency. Indicator of mechanical bioeffects, matters most with contrast enhanced US.
395
Stable vs transient cavitation?
Stable: microbubbles already present in the media, which expand and contract with the ultrasound wave pressure. Transient: Bubble oscillations become large enough that the bubbles collapse, causing shock waves and possibly tissue damage.
396
NCRP limits for thermal and mechanical indices in ultrasound?
NCRP (National Council on Radiation Protection and Measurements) says it's a risk/benefit discussion for TI over 1.0 or MI over 0.5.
397
Ultrasound thermal index limits?
TI \< 0.7 for OB imaging TI 1.0 - 1.5, don't scan more than 30 min TI 2.5 - 3.0, don't scan more than 1 min TI \> 3.0, don't use US
398
How much energy is needed for beta plus decay and what happens if you don't have enough?
1.02 MeV is needed (sum of energies of two eventual 511 keV photons). Excess proton turns into a neutron and emits a positron, which then annihilates creating the 511 keV photons. If you don't have the 1.02 MeV to do beta plus decay, the isotope can do electron capture, wherein an excess proton eats an inner shell electron to become a neutron, and then another electron fills the inner shell vacancy emitting characteristic radiation.
399
What type of shielding should be used for beta emitters?
Plastic shielding. Lead shielding can cause bremsstrahlung radiation.
400
How do you calculate effective half life?
Teffective = 1/Tphysical + 1/Tbiologic
401
What causes star artifact in a nuc med study?
Septal penetration in a collimator with hexagonally arranged holes. Often when imaging thyroid after high dose therapy using medium energy collimator instead of high energy collimator.
402
Gamma camera quality control tests and how often?
Field uniformity: - Extrinsic (with collimator): daily - Intrinsic (without collimator): weekly Energy window: daily Image linearity and spatial resolution: weekly Center of rotation: weekly
403
Quality assurance tests on dose calibrator and how often?
Linearity: Ensure accurate readout over range of activities (can use sheet of varied lead thicknesses to simulate activity decay or just wait for the tracer to decay). Checked QUARTERLY Accuracy: For standard radiotracer references, make sure the dose calibrator is giving you the right activity. Checked AT INSTALLATION and ANNUALLY. Constancy: Check reference isotope every day, make sure the measured activity stays constant. Should be within 5% of computed activity. Basically a mini accuracy test. Checked DAILY. Geometry: Make sure you get the same reading regardless of sample volume or size. Test with different vials and syringes used, with different dilutions of the same tracer dose. Checked AT INSTALLATION and AFTER DEVICE IS MOVED.
404
What do you do after a major or minor spill?
Major spill: Call the radiation safety officer, don't clean it up - clear area - cover with absorbent paper - indicate boundaries of spill, don't let contaminated people go anywhere - shield source if possible - notify RSO - decontaminate people Minor spill: Just clean it up you slob - make sure the patient is ok - confine spill/limit spread, don't let contaminated people go anywhere - clean up spill with damp absorbent material (outside to center) - survey clean up items (keep 10 half lives) - survey clean up people in a different area
405
Limit whole body dose/year? Single organ dose/year?
Whole body: 5 rem (0.05 Sv, 50 mSv) Single organ: 50 rem (0.5 Sv, 500 mSv) - same for extremity (50 rem)
406
What do you have to do for a reportable medical event?
- Call NRC within 24 hrs - Write NRC letter within 15 days - Notify referring doc within 24 hrs - Notify patient (or let referring do it)
407
What is the transportation index for radionuclides?
TI = Measured max dose at 1 meter at the time of shipping. Labels: White 1: No TI because rate at 1 meter so low Yellow 2: TI \< 1.0 mR per hour Yellow 3: TI \> 1.0 mR per hour
408
Tuning fork artifact on SPECT QC?
Error with center of rotation (misregistration error). Point source SPECT image will have a "tuning fork" configuration (2 lines in one direction, 1 in the other) rather than just looking like a point. Example: https://o.quizlet.com/vbrWbnrsdYQ9Dl8NedRPrA\_m.png
409
PET QA tests and how often to perform them?
Normalization: Scan calibrated position source in the FOV, which normalizes the detector elements. Do this MONTHLY Blank scan: Do a scan without anything in the field of view, helps keep attenuation correction accurate. Like "zeroing" the scanner. Do this DAILY
410
Most common location for choroid plexus tumor in an adult?
Fourth ventricle. In children, most commonly in the atrium of the lateral ventricle.
411
How do selective RF pulse bandwidth and slice selection gradient affect slice thickness?
Higher RF pulse bandwidth increases slice thickness. Higher slice selection gradient amplitude increases slice thickness. The equation: Slice thickness = RF bandwidth / (SS gradient \* some constant)
412
What are the three types of extra-calvarial hemorrhage in babies?
- Cephalohematoma: subperiosteal, bound by sutures, will probably tamponade - Subgaleal hematoma: not bound by sutures, can get really big and be life threatening (anemia, heart failure, hypovolemia) - Caput succedaneum: subcutaneous hemorrhage/fluid collection, usually resolves after a few days Image: https://upload.wikimedia.org/wikipedia/commons/0/0a/Scalp\_hematomas.jpg
413
Which must be done first, in- or out-of-phase sequence?
Out-of-phase imaging must be done first (2.2 msec at 1T), then the in-phase (4.4 msec). Reason for this is whether you can differentiate fatty liver from iron deposition. With a very short echo time (2.2 msec), iron will be bright, and due to opposing phases fat will be dark. Iron will lose signal quickly thanks to T2\* effects, so will be darker at 4.4 msec, and even darker at 6.6 msec. So if you wait to do out-of-phase images at 6.6 msec, you will have a hard time telling fatty liver from iron overload.
414
Which sequence has the worst artifact from Eddy currents?
DWI, thanks to large amplitude and long duration of diffusion sensitizing gradients.
415
How do you fix cross talk artifact on MRI?
You can either leave a little gap between slices, or interleave slice aquisition (i.e. do all odd numbered slices then all even numbered).
416
What things can make dielectric effect artifact worse and how do you fix it?
Caused by abdominal girth approaching RF wavelength, causing constructive and destructive interference, looks like blob of dark signal in the central abdomen. Make it worse: - Higher magnetic field (3T) - Large belly - Ascites Fix it: - Use a 1.5T magnet - Drain the ascites - Use dielectric pads (placed between patient and anterior body coil) - Parallel RF transmission (?)
417
"India ink" artifact is what type of artifact?
Type 2 chemical shift artifact
418
Carcinoid syndrome usually affects which valves, and does it cause stenosis or insufficiency?
Usually affects right heart valves, causing tricuspid insufficiency and pulmonic valve stenosis. (mnemonic TIPS)
419
Does fibrous dysplasia of the skull affect the inner or outer table more?
Affects outer table more.
420
What is the approximate likelihood of amorphous breast calcs representing cancer?
20%, usually DCIS or IDC
421
In what setting is ultrasound mechanical index most important?
Mechanical index is MOST important in the setting of a contrast-enhanced ultrasound examination. Ultrasound contrasts are based on microbubbles. If the mechanical index is too high it can cause the bubbles to rupture potentially resulting in capillary damage.
422
What is the average time to recurrence for completely resected non-invasive thymoma?
5 years. Therefore, annual CT is recommended for 5 years, followed by alternating CT/plain film until year 11.
423
Renal activity in Ga-67 imaging is abnormal after how long?
24 hours. Ga-67 is normally excreted by the kidneys, but after 24 hours residual renal activity is abnormal. DDx: obstruction, renal failure, pyelo, renal neoplasm.
424
What are the types of pancreas divisum?
There are three recognized subtypes of pancreatic divisum. Type 1 is the classic and most common presentation (70% of cases) in which there is no connection between the dorsal and ventral ducts. In type 2 (20 - 25 % of cases) the minor papilla drains all of the pancreas and the major papilla only drains the bile duct. And lastly, in type 3 (5-6% of cases) there is partial fusion of the ventral and dorsal ducts, but the connection is inadequate.
425
What marker is specific for Wegener's?
C-ANCA
426
What is the limit for x-ray tube leakage?
Should not exceed 1.0 mGy at 1 meter from source.
427
Is the sternalis muscle more commonly unilateral or bilateral?
Unilateral approx 2/3 of the time.
428
What is the approximate total dose for a screening mammogram?
Around 8 mGy. Each view tends to be 1-3 mGy, so four total views averages about 8 mGy. MQSA max average glandular dose for single CC view is 3 mGy.
429
Which direction does the nipple most commonly displace after reduction mammoplasty?
Superiorly. Glandular tissue will be displaced inferiorly.
430
Screening mammo is associated with what percent reduction in mortality for women over 50?
30%
431
Per MQSA, how often do you have to do darkroom fog quality control testing?
Semi-annually
432
Enhancing breast mass on MRI with lobulated margins and non-enhancing septations?
Fibroadenoma. Enhancing masses with ENHANCING septations more likely malignancy
433
How often do you have to perform processor quality control for film-screen mammo?
Daily
434
A breast mass with a spiculated margin on MRI has what approximate likelihood of malignancy?
80% (BIRADS 4)
435
Per MQSA, how often do you have to do compression quality control testing?
Semi-annually.
436
What is the typical Bucky factor in mammo?
2-3 (i.e., 2-3x dose) Grids are not used in mag views.
437
Approx what percent of well-circumscribed, solid, non-palpable masses on screening mammo are malignant?
1.4% (BIRADS 3)
438
Per MQSA, how often do you have to test fixer retention for film mammo?
Quarterly.
439
What radiotracer is approved for breast imaging in the US?
Tc-99 Sestamibi
440
Paget disease of the breast is associated with which type of breast cancer?
Ductal carcinoma. 4 stages of Pagets: 0 - DCIS confined to epidermis 1, 2 - DCIS deep to lesion, 2 is more extensive 3 - IDC deep to lesion
441
Increasing breast density 18 months after lumpectomy+radiation most likely what?
Most likely recurrence. Post-radiation change should peak approx 6 months after treatment, so any increasing density, trabecular thickening or skin thickening after 12 months should be considered recurrence until proven otherwise.
442
What type of breast cancer is associated with prominent lymphoid infiltration on path?
Medullary carcinoma. Tend to occur in younger women. Not usually associated with calcs. Circular/oval mass on mammo with ill-defined or circumscribed margins.
443
What percent more breast cancers will be detected by adding physical exam to screening mammo?
Approx 9% according to Breast Cancer Detection Demonstration Project (BCCDP)
444
On bone scan, what is the "Mickey mouse" sign in the spine associated with?
Paget's disease - uptake in the pedicles and spinous process.
445
When does the fetal thyroid begin to concentrate iodine?
10-12 weeks.
446
What other fracture is most associated with Jefferson fracture?
C2 fracture in 1/3 of patients.
447
When should a woman who received mantle radiation at 21 start screening mammo?
At 29 years old. 8 years after radiation, not before age 25. American Cancer Society also recommends screening MRI.
448
Approx what percent of parathyroid adeomas are ectopic and what is the most common location?
15%, and mediastinal. If labs indicate hyperparathyroidism and the neck mibi scan is negative, look at the mediastinum.
449
On cardiac MR, which sequence is most useful for differentiating acute from chronic infarct?
T2. Acute infarct will show high signal due to edema, whereas chronic will be dark due to scar.
450
What is the approximate entrance air kerma for an abdominal radiograph?
3 mGy
451
Wilm's is associated with a deletion on the short arm of which chromosome?
11. wiLms eLeven
452
Approximate spatial resolution for digital mammo?
7 lp/mm. Screen film mammo: 15 lp/mm digital mammo: 7 lp/mm digital radiography: 3 lp/mm CT: 0.7 lp/mm MRI: 0.3 lp/mm
453
Most common site of distant mets for Wilms?
Lung. Approx 5-10% of cases have mets, 85-90% of mets are to lung, 10% to liver.
454
Minimum duration a facility must keep mammography records for a patient?
5 years, assuming the patient does not request them transferred elsewhere.
455
What can happen to people living in iodine deficient areas after getting an enhanced CT?
Delayed hyperthyroidism, approx 4-6 weeks after the scan.
456
Via which route does phylloides metastasize?
Hematogenous, in approx 10% of cases.
457
Who is at greatest risk for emphysematous cholecystitis?
Elderly diabetic males
458
Is mucoepidermoid or adenoid cystic carcinoma of the trachea more likely to extend beyond the lumen?
Adenoid cystic has a propensity to extend into the mediastinum
459
Larmor frequency of hydrogen at 1 Tesla?
42 MHz
460
Primary cardiac osteosarcoma almost exclusively affects which chamber?
Left atrium. Tends to invade retrograde into pulmonary veins. In contrast, cardiac angiosarcoma likes the right atrium (right atrioventricular groove).
461
About how much more is entrance skin dose compared to entrance air kerma?
Approx 50%.
462
Approx what percentage of children with meconium ileus will turn out to have cystic fibrosis?
\> 75%. On the other hand, only about 5-20% of children with CF will present with meconium ileus.
463
How do you calculate CTDI\_w from a peripheral and central CTDI?
CTDI\_w = 2/3 peripheral + 1/3 central. E.g., if peripheral CTDI = 15 mGy and central CTDI = 6 mGy, CTDI\_w = 2/3(15) + 1/3(6) = 10 + 2 = 12 mGy.
464
Are sacrococcygeal teratomas found in children \< 2 months old more or less likely to be malignant?
Less likely. Only 10% of sacrococcygeal teratomas in children less than 2 months old are malignant, whereas 90% are malignant in children greater than 2 months old.
465
Maximum SAR for head and body imaging per the FDA?
3 W/kg for head imaging over 10 minutes 4 W/kg for body imaging over 15 minutes
466
What nuc med tracer is used for testicular imaging?
Tc-99 pertechnetate.
467
During which phase of MAG-3 renal imaging is the split function (differential function) evaluated?
Cortical phase. Differential function should be between 45 - 55% between kidneys.
468
Most common mets to the spleen?
Lung, stomach, pancreas.
469
What is the distribution and size of follicles in PCOS?
12 of more peripheral follicles measuring 2-9 mm (\< 10 mm). Criteria also say ovarian volume should be \> 10 cc.
470
How quickly do most V/Q defects from PE resolve after anticoagulation?
Most resolve by 3 months. Those that don't usually remain permanently.
471
Where on the package can the radiation warning labels be attached?
Any side, but not the top or bottom (in case the box is stacked during shipping).
472
Duct of Luschka?
Accessory bile duct that may drain directly from the liver into the gallbladder body. Injury of this during cholecystectomy can cause post-op bile leak.
473
What is the association with thymic carcinoid?
MEN type 1. Also pituitary, parathyroid, and pancreatic neoplasms.
474
Vertebral collapse with air in the compressed vertebral body?
Osteonecrosis. Apparently the air in the compressed vertebral body is associated with osteonecrosis rather than mets or myeloma.
475
Hemorrhagic mediastinitis is associated with which (infectious) disease?
Inhalational anthrax.
476
How long post-op can you have normal activity around a prosthesis?
For cemented prostheses, 6 months - 1 year. For non-cemented, 2 - 3 years.
477
What is the difference between T3 and T4 staging in lung cancer?
Both invade adjacent structures. The difference between T3 and T4 is whether it invades VITAL structures: Invasion of NON-VITAL structures (including the chest wall, mediastinal pleura, diaphragm and pericardium) is considered T3 disease. Invasion of VITAL structures (including mediastinal fat, heart, trachea or carina, esophagus, great vessels, the recurrent laryngeal nerve or the vertebral body) is considered T4 disease.
478
What are the TR and TE associated with T1, T2 and proton density sequences?
PD: long TR (2000 - 3000 ms), short TE (25 - 30 ms) T1: short TR (\< 500 ms), short TE (\< 20 ms) T2: long TR (\> 2000 ms), long TE (\> 70 ms)
479
Are thoracic neuroblastomas more or less likely to be calcified?
Thoracic neuroblastomas are less likely to calcify (about 50% vs 80-90% for abdominal tumors).
480
Most likely anterior mediastinal mass in a child?
Lymphoma, mostly hodgkin (3-5x more likely than non-hodgkin).
481
What syndrome is thymic carcinoid tumor associated with?
MEN type 1. - male predominance - most common neuroendocrine tumor of the thymus - 50% functionally active, mostly causing Cushing syndrome from oversecretion of ACTH
482
80% of cases of Hirschsprung will have presented by what age?
6 weeks of life.
483
What maternal factors increase the risk for small left colon syndrome?
- Maternal diabetes - Mag sulfate treatment for eclampsia
484
How long must a patient be surveilled after EVAR?
The rest of their life, to make sure there isn't graft failure/endoleak etc.
485
What organism is associated with MALT lymphoma of the stomach?
H. pylori infection in \> 85% of cases. When lymphoma is confined to the stomach, treatment of H. pylori will result in complete regression in 70-80% of cases.
486
Most common cause of tricuspid insufficiency?
RV dilation with dilation of the annulus. Mostly secondary to left heart failure or pulmonary hypertension/cor pulmonale.
487
Type of breast CA most likely to be associated with a cyst?
Papillary
488
Most common pediatric renal mass?
Wilms tumor
489
Most common location of the cecum in patients with malrotation?
High and medial, near the umbilicus. Cecum will be in normal position in 20% of patients with malro.
490
What is a predisposing factor for fibromatosis colli?
Fibromatosis colli almost always related to birth trauma like forceps delivery. Presents at 2-4 weeks of age. Treatment is physical therapy.
491
On VQ scan, triple match defect in lower lung zone is what probability?
Intermediate probability. Triple match in upper or middle lung zones are low prob.
492
Most common presenting symptom for symptomatic renal AVM?
Gross hematuria. Flank pain and hypertension are less common.
493
What is the gender predilection for Mournier-Kuhn?
Males, like 19:1.
494
Which pancreatic duct is which?
Wirsung is ventral, drains head and uncinate process to major papilla with the CBD. Santorini is dorsal, drains body and tail, normally connects to Wirsung with maybe a little accessory duct draining to the minor papilla. In divisum, the connection to Wirsung doesn't happen, so the whole body and tail drain to the minor papilla.
495
Where does esophageal atresia usually occur?
Junction of the upper and mid thirds of the esophagus.
496
X-ray tubes operating above 70 keV must contain total filtration of how many mm aluminum equivalent?
2.5 mm. Total filtration includes tube wall or any added filtration. At 80 keV, 2.5 mm aluminum is 1 half value layer.
497
How does beam collimation affect image contrast?
Contrast improves with increased collimation, since there will be less scatter to degrade contrast.
498
Renal transplant artery stenosis should be suspected at what RIR ratio?
RIR ratio = renal artery to iliac artery ratio \> 2 is suspicious for stenosis
499
What is the regulation regarding the door of the hot lab?
It must be either locked or under surveillance at all times.
500
Which breast carcinoma has the best prognosis?
Tubular
