Random Flashcards
Discuss peritoneal CSF pseudocyst (cause, appearance, etc.)
Rare complication of VP shunt catheter placement, time from placement to appearance 3weeks-5years
thin walled cystic mass around the tip of the VP shunt. US method of choice, CT also good. Does not necessarily need to have septations.
treatment is excision of cyst or repositioning of VP shunt tip
What is technique (contrast timing) and values to diagnose adrenal adenoma with CT C+
C- scan, initial enhanced scan (60sec) and delayed enhanced scan (15min)
Adrenal adenomas show increased washout compared to malignant lesions
(Enhanced CT - delayed CT)/(enhanced CT) *100
If there is over 60% washout, it is diagnostic of an adrenal adenoma. Less than 60% remains equivocal and should proceed to biopsy or MR
Define encapsulating peritoneal sclerosis
Complication of peritoneal dialysis with thickening of the peritoneum which encapsulates and obstructs the small bowel.
Define circumaortic left renal vein (aka circumaortic renal collar)
Accessory or supernumerary left renal vein which passess posterior to the aorta, apart from the normal renal vein passing anterior to aorta.
Name the syndrome:
anterior interposition of the colon to the liver reaching the under-surface of the right hemidiaphragm with associated upper abdominal pain
Chilaiditi syndrome
Most common cause of appendiceal mucocoele
Mucosal hyperplasia
Other causes:
Mucinous neoplasms (cystadenoma, cystadenocarcinoma)
Carcinoid
Adjacent caecal tumour
What is the name of the intermediate stage between acute pyelonephritis and renal abscess, and is a focal region of interstitial nephritis.
Lobar nephronia
How to differentiate inguinal from femoral hernia on CT? (AJR 2007)
if the hernia sac extends medial to the pubic tubercle, it is almost certainly an inguinal hernia.
if the hernia sac remains lateral to the pubic tubercle and compresses the femoral vein, it is almost certainly a femoral hernia
Ddx hypervascular small bowel intraluminal tumor that typically causes intussusception
Carcinoid tumor
Metastasis
GIST
What are the primary risk factors for small bowel adenocarcinoma? (5)
Hereditary nonpolyposis colorectal cancer
Familial adenomatous polyposis
Peutz-Jeghers (hereditary intestinal polyposis syndrome)
Celiac disease
Crohn’s disease
What are the primary risk factors for small bowel lymphoma? (6)
Celiac disease Crohn's disease SLE immunocompromised state post-chemotherapy extra-intestinal lymphoma
What is the most common primary small bowel neoplasm?
Carcinoid tumor (44%)
The other most common SB primary neoplasms are:
Adenocarcinoma
lymphoma
GIST
Metastases are more common than primary tumors.
What are the typical imaging findings of small bowel adenocarcinoma?
Focal unilocular, circumferential mass with shouldering of the margins and obstruction.
Often show moderate enhancement
Duodenum is most common site, followed by jejunum.
Frequently metastasize to liver/peritoneum
mesenteric fat stranding can represent extraluminal infiltration (favors ADK over lymphoma)
What is typical imaging appearance of small bowel lymphoma?
thick walled infiltrating mass with aneurysmal dilatation without obstruction.
bulky mesenteric/retroperitoneal lymphadenopathy and splenomegaly help differentiate from adenocarcinoma
most common site: distal ileum, contains large amount of lymphoid tissue.
Enteropathy associated T-cell lymphoma of the small intestine is associated with what pathology?
Celiac disease
Most common location for carcinoid tumor of the gastrointestinal tract?
Small intestine (42%)
rectum (27%)
appendix (24%, but previous data claims it is most common location)
stomach (9%)
radiographics 2007
What is the typical imaging appearance of carcinoid tumor of small bowel?
partly calcified mesenteric mass with desmoplastic reaction and retraction of adjacent small bowel loops with wall thickening. This often represents mesenteric metastasis/extension, with the primary lesion being a small intraluminal mass.
It is a hypervascular tumor.
What is carcinoid syndrome?
Presents in less than 10% of patients with carcinoid tumor
caused by overproduction of serotonin
symptoms are cutaneous flushing, diarrhea and bronchoconstriction. Heart failure can occur from serotonin-induced fibrosis of tricuspid/pulmonary valves.
What is typical imaging appearance of GIST?
Well defined exophytic mass with heterogeneous enhancement and clear delineation from the mesentery.
hypervascular mets to the liver. Lymphadenopathy is atypical.
can show aneurysmal dilatation.
intraluminal mass is less common.
obstruction rare.
In a patient with crohn’s disease and bowel wall thickening causing small bowel obstruction that is refractory to medical therapy, what differential diagnosis should be considered? (1)
Underlying malignancy (adenocarcinoma)
What is splenic SANT? CT/MRI appearance?
Sclerosing Angiomatoid Nodular Transformation of the spleen
rare benign non-neoplastic vascular splenic neoplasm of uncertain etiology.
On CT, the typical pattern is a solitary, well-circumscribed splenic mass with smooth or lobular borders. Mildly hypodense on NECT with rim enhancing and radiating vascularized tissue penetrating from the periphery toward the center with progressive central enhancement on delayed imaging - “spoke wheel” pattern.
On MRI, most commonly heterogeneous but low to intermediate signal intensity on T1-weighted imaging.
On T2-weighted sequences typically low signal - in contrast to most differential diagnosis.
Remains non-specific with malignant lesions being in DDx therefore requires splenectomy.
What is the name of a stomach adenocarcinoma metastasis to the ovary?
Krukenberg tumor
Most important sequence to assess peripheral zone for prostate cancer on MR? Transitional zone?
Peripheral zone: DWI
Transitional zone: T2, because BPH nodules restrict and enhance
When assessing fibrotic changes in the retroperitoneum, what distribution of involvement helps differentiate retroperitoneal fibrosis from Erdheim-Chester disease?
inferior vena cava and pelvic ureters are typically spared in erdheim-chester disease
Give ddx for multiseptated cystic renal mass (complex renal cyst)
Benign multilocular renal cyst Multilocular cystic RCC (rare) Multilocular cystic nephroma Mixed epithelial and stromal tumor Infected cyst or abscess
What RCC subtype is typically hypovascular? Also give its typical MRI appearance
Papillary renal carcinoma
HypoT2
Hypointense on gradient echo (artifact from hemosiderin)
What is imaging Ddx of papillary renal carcinoma
AML with minimal fat
Oncocytoma
Clear cell/chromophobe RCC
What is the mecanism of pneumatosis intestinalis in a patient having received recent chemotherapy (ex: bone marrow transplant)
The chemotherapeutic agents can cause GI mucosal damage (denudation), which can allow intraluminal air to enter the damaged or dissected bowel wall
It is benign.
What is the most common cause of omental caking?
Give differential diagnosis
Most common cause is metastases from ovarian, gastric or colon cancer
Ddx:
Tuberculous peritonitis
Lymphoma
mesothelioma
How do you differentiate choledocholithiasis from pneumobilia and bile flow artifacts?
On axial images:
choledocholithiasis is typically located in a dependent position in the duct
pneumobilia is antidependent
bile flow artifacts are typically located centrally
What is the differential diagnosis for a striated nephrogram? (5)
Pyelonephritis Urinary obstruction Renal vein thrombosis Renal contusion Hypotension
Name this finding:
Portal hypertension causes enlargement of the splenic vein, formation of perisplenic collaterals and eventually small areas of intrasplenic hemorrhage. The remnants of these tiny foci of hypertensive bleeding, which are composed of hemosiderin, fibrous tissue, and calcium, are referred to as ___ or ___
Siderotic nodules or gamna-gandy bodies
Blooming artifact on gradient-echo sequence is pathognomonic for this entity
Name the following types of hernias:
1- Herniation of the appendix through the inguinal canal
2- Herniation of a Meckel diverticulum through the inguinal canal
3- Incarceration of the appendix within a femoral hernia
1- Amyand hernia
2- Littré hernia
3- De Garengeot’s hernia
What are the typical CT features of retractile mesenteritis? (subgroup of sclerosing mesenteritis)
This disorder is usually confined to the mesentery and can occasionally calcify.
Presents as a soft tissue mass that can contain fat and calcifications extending from the root of the mesentery toward the small bowel. This can lead to retraction and kinking of the bowel, resulting in crampy abdominal pain.
What is the difference between primary and secondary hemochromatosis? (give etiology)
Primary hemochromatosis is an autosomal recessive genetic disorder. The affected individual has increased iron absorption (2-3x normal).
Secondary hemochromatosis is a nongenetic cause of iron accumulation. Causes:
Increased absorption (ex: cirrhosis)
myelodysplastic syndrome
anemias related to ineffective erythropoiesis (thalassemia, congenital dyserythropoietic anemias, sideroblastic anemias)
exogenous increase by ingestion, parenteral infusion or multiple transfusions
In a patient with hemochromatosis, what findings will you see in the liver on in and out-of-phase imaging?
Contrary to steatosis, the signal of the liver parenchyma will be decreased on the in-phase sequence when compared with the out-of-phase sequence.
What pathologies cause iron deposition in the kidneys and what is the MR finding?
Iron deposition in the kidneys is due to intravascular hemolysis, in cases such as:
Heart valves
Paroxysmal nocturnal hemoglobinuria
Hemolytic crises of sickle cell disease
On T1 and T2 weighted images, the renal cortex will be hypointense in relation to the medulla (reversed corticomedullary differentiation)
What is the difference in patterns of iron deposition between a reticuloendothelial and a parenchymal deposition pattern?
In a reticuloendothelial pattern, the spleen and bone marrow are involved (hypointense), whereas the pancreas is spared.
It is typically due to multiple transfusions.
In a parenchymal pattern, the pancreas is involved (unless mild disease), whereas the spleen and bone marrow are spared.
It is typically due to increased iron absorption.
The liver is affected in both patterns.
What percentage of adrenal myelolipomas contain calcifications?
20%
What is the washout percentage needed to call lipid poor adrenal adenoma on CT?
absolute washout:
[(HUportal venous phase) - (HUdelayed)] / [(HUportal venous phase) - (HUnon-enhanced)] x 100
> 60% washout is highly suggestive of adrenal adenoma
relative washout
[(HUportal venous phase) - (HUdelayed)] / (HUportal venous phase) x 100
> 40% washout is highly suggestive of adrenal adenoma
Three most common sites of origin for adrenal metastasis?
Breast
Lung
Melanoma
What percentage of pheochromocytomas are malignant?
10%
True or false:
There are no reports in the literature of hypertensive crisis in patients with pheochromocytoma after non-ionic contrast injection
True
Non ionic contrast is safe in patients with pheochromocytoma, but if it is suspected prior to the study, it is preferred to begin with a C- CT or MRI.
What hereditary conditions are associated with pheochromocytoma
MEN IIa, IIb: almost always bilateral
Neuroectodermal disorders (TS, VHL, NF1, Sturge-Weber)
Carney triad (extra-adrenal pheo)
familial pheochromocytoma
What is the DDx of bilateral adrenal masses?
Mets Pheochromocytoma Lymphoma Granulomatous disease (TB, histo) Adenoma
Adrenal hemorrhage is bilateral 20% of the time
DDx of non tumoral calcification in the adrenal gland
Previous infection (TB)
Previous hemorrhage
Idiopathic
Causes of adrenal insufficiency
Idiopathic - Addison disease (70%) Fungal infection Granulomatous infection Bilat hemorrhage - addesonian crisis Bilat metastases - rare
What is the arterial and venous anatomy of the adrenal glands
Arterial:
Superior suprarenal artery, originates from subphrenic artery
middle suprarenal artery, originates from aortra
inferior suprarenal artery, originates from renal artery
Venous:
Right suprarenal vein drains into IVC
Left suprarenal vein drains into left renal vein
What is the normal thickness of the adrenal gland on MRI?
2-6mm
Normal length is 2-4cm
On chemical shift imaging, a loss of signal of what % is considered diagnostic of an adrenal adenoma?
A loss of signal of more than 20% on out of phase imaging is considered diagnostic of an adrenal adenoma.
TRUE OR FALSE
Ah heterogeneous adrenal lesion on MRI cannot be an adrenal adenoma
FALSE
Small foci of altered signal can be seen within an adrenal adenoma owing to cystic change, hemorrhage or variations in vascularity
What is prevalence of adrenal cysts?
They are rare
The frequency of adrenal cysts seen at autopsy studies ranges from 0.064% to 0.18%
What disease can be a secondary effect of bilateral adrenal hemorrhage?
Addison disease
Name etiologies of adrenal hemorrhage
Trauma Adrenal vein thrombosis Stress Hypotension Bleeding diathesis
TRUE OR FALSE:
The signal of adrenal cortical hyperplasia can drop on out of phase imaging
TRUE
Not necessarily the case, but can happen, especially in patients with nodular cortical hyperplasia. Adrenal cortical hyperplasia otherwise follows the normal signal intensity of the adrenal glands.
What is the eponym and what are the causes of primary hyperaldosteronism?
Conn Syndrome
Causes:
adrenal cortical adenoma (33%)
bilateral adrenal hyperplasia (66%)
adrenocortical carcinoma
Can also occur in renin related hypertension
Functional adrenocortical carcinoma can present with what syndromes?
Cushing Syndrome
Conn Syndrome
feminization/virilization
What is MRI appearance of adrenocortical carcinoma?
Typically large at diagnosis, 6-20cm
heterogeneous T1 and T2 (typically hetero T2hyper)
Can contain hemorrhage and necrosis
Can contain intracytoplasmic lipid, resulting in drop of signal on out-of-phase imaging
If large, tends to invade the adrenal vein and IVC
Heterogeneous enhancement
On CT, up to 33% have calcification
What syndromes is adrenocortical carcinoma associated with?
Beckwith-Wiedemann syndrome
Li-Fraumeni syndrome
Carney complex
multiple endocrine neoplasia type 1
TRUE OR FALSE:
Almost all cases of adrenal gland lymphoma are bilateral
FALSE
50% are bilateral
What is the appearance of adrenal lymphoma on MRI?
hypoT1
heterogeneous hyperT2
minimal progressive contrast enhancement
No drop on in-and-out of phase imaging
When assessing an adrenal mass such as an adenoma, what should be considered in the presence of contralateral adrenal atrophy?
That the mass is functional, because pituitary adrenocorticotropic hormone secretion is suppressed by elevated cortisol levels.
What percentage of adrenocortical carcinomas are functionally active?
30-40%
What is the most common location of metastasis in adrenocortical carcinoma?
Liver
other locations: lung, lymph nodes
What is CT and MRI appearance of pheochromocytoma?
CT:
Homogeneous (if small) or heterogeneous
Can have hemorrhage, necrosis, cystic content
Can have intracellular lipid
Can contain calcification
Avidly enhancing with variable washout characteristics (can mimic adenoma)
MRI:
Moderate to intensely T2 hyper (light bulb appearance)
avid contrast enhancement
TRUE OR FALSE
The presence of macroscopic fat in an adrenal tumor is diagnostic of a myelolipoma
FALSE
Although it is the most likely diagnosis, there are cases of macroscopic fat in other adrenal tumors such as:
adenoma pheochromocytoma adrenocortical carcinoma metastasis collision tumors (myelolipoma + another lesion)
What are the most common primary tumors in patients less than 40 years of age with adrenal metastases?
lymphoma
leukemia
lung cancer
stomach cancer
What is the course of the urachus?
From the umbilicus to the dome of the bladder
Midline, infraumbilical, soft-tissue mass with calcification is ______________ until proven otherwise
Urachal carcinoma
What is the typical location of urachal carcinoma?
Characteristically located at dome of bladder in the midline, or slightly off midline
80% are adenocarcinoma
What is the CT appearance of chronic cystitis secondary to schistosomiasis?
Nodular wall thickening progresses to contracted, fibrotic, thick-walled bladder with curvilinear calcification
Urinary bladder schistosomiasis is associated with what malignancy?
Squamous carcinoma of the bladder
In which part of the rectum does the peritoneum attach?
Middle third.
The proximal third has peritoneum laterally and anteriorly whereas the middle third has peritoneum attaching anteriorly. There is no peritoneum in the distal third of the rectum.
In rectal carcinoma staging, what anatomic landmark seperates T2 from T3?
In T2 there is involvement of the muscular wall of the rectum. When the tumor goes though the muscular wall of the rectum, it is considered T3.
In TNM classification of rectal carcinoma, what is N0, N1 and N2?
N0: none
N1: up to 3 nodes
N2: 4 nodes or more
In rectal carcinoma staging, what anatomic landmark seperates T1 from T2?
Involvement of the muscular wall of the rectum (muscularis propria).
What is the criteria when assessing for nodal disease in rectal carcinoma?
Mesorectal lymph nodes and superior rectal vessels are typically involved.
5mm in short axis (low sensitivity and specificity)
irregular nodal outline
signal heterogeneity on T2WI
