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
Why is determination of extramural vascular invasion important in rectal carcinoma staging?
Because almost all patients with invasion of large vessels deep to muscularis propria have or will soon develop liver metastases.
What is the primary determinant of the T staging in anal carcinoma?
size of tumor
In the assessment of an anorectal tumor on MRI, if the mucosa/submucosal is uninvolved, which primary should you consider?
GIST
Carcinoid
Adenocarcinoma and squamous cell carcinoma arise from the mucosa/submucosa.
Ulcers in the distal duodenum (D3, D4) or proximal jejunum, especially if multiple, are suspicious for what pathology?
Zollinger Ellison syndrome
What are the surgical changes in a roux-en-y gastric bypass?
1- The stomach is partitioned into a small fundal component (gastric pouch) and an excluded component (excluded stomach)
2- Jejunum is divided 25-50cm distal to ligament of Treitz
3- The distal limb of the divided jejunum (alimentary limb) is brought up to the gastric pouch. It can be brought up anterior or posterior to the transverse colon. An end-to-end or end-to-side gastrojejunal anastomosis is created; when end-to-side there is a short blind ending jejunal stump.
4- The proximal limb of the divided jejunum (biliarypancreatic/afferent limb) is anastomosed to the small bowel 75-150cm distal to the gastrojejunostomy to create a common channel that continues to the ileum. It is a side-to-side anastomosis.
What is the normal diameter of the stoma of the gastrojejunal anastomosis in a roux-en-y gastric bypass?
8-12mm
What is the normal size of the gastric pouch in roux-en-y gastric bypass?
15-20mL (but can vary significantly)
In roux-en-y gastric bypass, stricture at the gastrojejunal anastomosis typically appear after how long?
4 weeks post operative
Which presentation of marginal ulcers post roux-en-y is more common:
Marginal ulcer at the gastrojejunal anastomosis
Marginal ulcer in the Roux limb abutting the anastomosis
Marginal ulcer in the roux limb abutting the anastomosis. It is believe that the ulcers are due to chronic exposuer of the mucosa to gastric acid.
What are the complications of roux-en-y gastric bypass?
Leak
Anastomotic stricture
Marginal ulcer
Acute or chronic Jejunal ischemia (roux limb)
Giant jejunal ulcers in chronic jejunal ischemia
Small bowel obstruction from various etiologies
Internal hernia
Intussusception
Gastro-gastric fistula
What is the most common cause of small bowel obstruction in laparoscopic roux-en-y bypass?
INTERNAL HERNIAS are the most common cause of small bowel obstruction in laparoscopic roux-en-y bypass.
Adhesions are the most common cause of small bowel obstruction in open roux-en-y bypass.
In patients with roux-en-y bypass, where do internal hernias occur?
Through a defect in the mesocolon (retrocolic roux limb)
Defect in the small bowel mesentery (jejunojejunal anastomosis)
Defect posterior to the Roux limb (Peterson defect)
What is the typical location of an intussusception in patients with roux-en-y bypass?
Typically occurs at the jejunojejunal anastomosis, with the staple line at this anastomosis presumably acting as the lead point.
Rare cause of SBO.
Where is the gastric band positioned in laparoscopic adjustable gastric banding?
About 2cm below the gastroesophageal junction
What is the normal appearance of a gastric band on plain radiograph?
2cm below GE junction
oblique orientation with lateral side above medial side just beneath the medial aspect of the left hemidiaphragm.
The phi angle (angle created by the intersecting lines through the spinal column and horizontal axis of the band) is normally between 4 and 58 degrees.
In laparoscopic adjustable gastric banding, what is the normal size of the gastric pouch?
Normal diameter of of 4cm, corresponding to a volume of 15-20mL.
What are the potential complications of laparoscopic adjustable gastric banding?
Stomal stenosis (band is too tight) Malpositioned band Pouch dilatation (from stomal stenosis, band slippage or chronic volume overload) Distal band slippage (causes obstruction, volvulus) Gastric perforation Gastric volvulus Intraluminal band erosion Port infection or eversion Tubing disconnection/kink
What is the volume of the residual stomach in laparoscopic sleeve gastrectomy?
Approximately 100mL
What are the potential complications of laparoscopic sleeve gastrectomy?
Gastric leak Abscess Gastric stricture/outlet obstruction Gastric dilatation GERD Splenic injury/infarction
TRUE OR FALSE
A hyperechoic renal mass is specific for angiomyolipoma.
FALSE
It is a non-specific appearance and overlaps with RCC. Another study or demonstrating stability on previous is necessary to diagnose AML.
TRUE OR FALSE
Calcification is a typical finding in angiomyolipoma of the kidney
FALSE
AML does not calcify. If there is calcium, consider RCC.
difference between bochdalek and morgagni hernia?
Bochdalek:
big
back and medial, left sided
babies
bad (pulmonary hypoplasia)
Bochdalek is at the back
Morgagni:
herniation through foramen of morgagni anterior and through sternocostal angle right sided (90%) small rare low risk of prolapse
Most common benign esophageal mass?
Leiomyoma
What are the values of normal and abnormal freePSA/totalPSA ratio?
<0.1: normal
0.1-0.15: equivocal
>1.5: abnormal
Where is the anterior fibromuscular stroma of the prostate located?
Anterior aspect of the prostate, it extends from the prostatic base to the midgland. It is non-vascular, should have no enhancement on post-gadolinium images.
On prostate MRI, what are potential causes of a T2 dirty peripheral zone?
normal
prostatitis
post radiotherapy change
low gleason score infiltrative cancer
Where is the prostatic neurovascular bundle located?
Lies posterolateral to the prostate gland
What is AAST grade 1 kidney injury?
grade I: contusion or non-enlarging subcapsular perirenal haematoma, and no laceration
What is AAST grade 2 kidney injury?
grade II: superficial laceration <1 cm depth and does not involve the collecting system (no evidence of urine extravasation), non-expanding perirenal haematoma confined to retroperitoneum
What is AAST grade 3 kidney injury?
grade III: laceration >1 cm without extension into the renal pelvis or collecting system (no evidence of urine extravasation)
What is AAST grade 4 kidney injury?
grade IV
- laceration extends to renal pelvis or urinary extravasation
- vascular: injury to main renal artery or vein with contained haemorrhage
- segmental infarctions without associated lacerations
- expanding subcapsular haematomas compressing the kidney
What is AAST grade 5 kidney injury?
grade V
- shattered kidney
- avulsion of renal hilum: devascularisation of a kidney due to hilar injury
- ureteropelvic avulsions
- complete laceration or thrombus of the main renal artery or vein
What is the DDx of primary perirenal space tumors and pseudotumors?
Lymphoma Leukemia Extramedullary hematopoiesis Metastases (bronchogenic carcinoma) Castleman disease Extraadrenal myelolipoma Erdheim-Chester disease
What is the DDx of renal tumors/pseudotumors with perirenal space extension?
Renal cell carcinoma Angiomyolipoma Xanthogranulomatous pyelonephritis Leiomyoma Hemangioma Lymphangioma
What is the DDx of retroperitoneal tumors/pseudotumors with perirenal space extension?
Lymphoma Leukemia Metastatic lymphadenopathy Malignant fibrous histiocytoma Liposarcoma Plasma cell neoplasms Retroperitoneal fibrosis
What is the DDx of a rindlike soft-tissue perirenal mass?
Lymphoma Leukemia Retroperitoneal fibrosis Extramedullary hematopoiesis Erdheim-Chester disease
What is the DDx of a perirenal mass with macroscopic fat?
Angiomyolipoma
Liposarcoma
Extramedullary hematopoiesis
Extraadrenal myelolipoma
What are the most commonly isolated pathogens in xanthogranulomatous pyelonephritis?
e. coli
Proteus mirabilis
What are the typical CT findings of xanthogranulomatous pyelonephritis?
Renal enlargement
Heterogeneous parenchymal enhancement/nonenhancement
Hydronephrosis
Abscess
Obstructive staghorn-like calculi
Extension of inflammation into perirenal space/retroperitoneum
What % of cases of perirenal lymphoma involve only the perirenal space?
<10%
Isolated perirenal lymphoma is unusual, and usually is due to contiguous spread from retroperitoneal or renal lymphoma.
What are the causes of retroperitoneal fibrosis?
idiopathic (70%)
radiation
medication
inflammation: pancreatitis, pyelonephritis
malignant: desmoplastic reaction, lymphoma
prolonged exposure to asbestos
retroperitoneal bleeding, e.g. after trauma or medical procedure
What is Rosai-Dorfman disease
Rare benign idiopathic proliferative disease that involves phagocytic histiocytes.
Mean age of 21yo
Present with massive lymphadenopathy, fever, leukocytosis, elevated ESR, and polyclonal hypergammaglobulinemia.
Perirenal hypodense soft tissue
What is the most common primary neoplasm to metastasize to the perirenal space? Why?
Lung cancer (less common: breast, melanoma, prostate) There are connections between the perirenal and mediastinal lymphatic vessels.
Name this hernia:
Lumbar hernia through the superior lumbar triangle
Grynflett-Lesshaft hernia
Name this hernia:
Lumbar hernia through the inferior lumbar triangle
Petit hernia
What are the borders of the superior lumbar triangle?
Internal oblique muscle anteriorly
12th rib superiorly
Erector spinal muscle posteriorly
What are the borders of the inferior lumbar triangle?
External oblique muscle anteriorly
Iliac crest inferiorly
Latissimus dorsi muscle posteriorly
A pheochromocytoma that develops along the path of the abdominal aorta, or at its bifurcation, arises from which structure?
Discuss the anatomy of this structure.
Organ of Zuckerkandl
The organ of Zuckerkandl comprises of a small mass of chromaffin cells derived from neural crest located along the aorta, beginning cranial to the superior mesenteric artery or renal arteries and extending to the level of the aortic bifurcation or just beyond. The highest concentration is typically seen at the origin of the inferior mesenteric artery..
What masses can arise from the organ of Zuckerkandl?
Pheochromocytoma
Neuroblastoma (rare)
What is a Sister Mary Joseph nodule?
Metastatic lesion involving the umbilicus.
Most common primary source is an intra-abdominal adenocarcinoma.
Explain how a peritoneal inclusion cyst forms (peritoneal pseudocyst)
Peritoneal inclusion cysts develop in premenopausal women with previous history of trauma, surgery, endometriosis or PID.
They are usually caused by accumulation of ovarian fluid that is contained by a peritoneal adhesion. The development of a peritoneal inclusion cyst depends on the presence of an active ovary and peritoneal adhesions. The normal peritoneum absorbs fluid easily. However, the absorptive capacity of the peritoneum is greatly diminished in the presence of mechanical injury, inflammation and peritoneal adhesions.
They typically appear as cystic masses with septations or loculated fluid collections within the pelvis. It conform to the peritoneal space and can show the ipsilateral ovary within it or within its wall.
Name this syndrome:
Complete occlusion of the abdominal aorta distal to the renal arteries
Leriche syndrome
What is the location of the rectosigmoid junction?
By anatomists: At the level of S3
By surgeons: At the level of the sacral promontory
What is the normal T2 signal of the 3 layers of the rectal wall?
Mucosa: Low signal fine line
Submucosa: High signal layers
Muscularis propria: two low signal layers (outer longitudinal and inner circular)
What are the superior and inferior borders of the anal canal?
Anorectal sling and anal verge
In the TNM staging of rectal cancer, what is considered T1?
the tumor invades the submucosa
In the TNM staging of rectal cancer, what is considered T2?
The tumor involves the muscularis propria but does not cross it
In the TNM staging of rectal cancer, what is considered T3?
The tumor extends beyond the muscularis propria into mesorectal or pericolic fat
In the TNM staging of rectal cancer, what is considered T4?
The tumor invades adjacent organs or perforates the visceral peritoneum
In rectal cancer, what T stage is treated with local excision? What T stage requires preoperative chemoradiation?
Excision: T1-T3B
Preop chemoradiation: T3C/D-T4
What is the vascular drainage of:
1- Upper two-thirds of the rectum
2- Low third of the rectum
1- Superior rectal vein (into IMV then portal system)
2- Middle and inferior rectal veins (into internal iliac vein and then IVC, bypassing liver)
What are the imaging findings in oriental cholangiohepatitis?
It is a diagnosis of exclusion (other causes of biliary stricture should be excluded first), however the best diagnostic clues are:
Intra and extrahepatic biliary dilatation and multilevel strictures
Intraductal pigmented calculi usually in the absence of gallbladder calculi
Regions of segmental liver atrophy (particularly lateral aspect of the left hepatic lobe) secondary to chronic biliary obstruction.
Which components of the liver are atrophied in cirrhosis secondary to primary sclerosing cholangitis?
Atrophy of the entire liver with the exception of the caudate lobe which is hypertrophied in almost all cases (68-98%).
What is the rate of development of cholangiocarcinoma in patients with primary sclerosing cholangitis? Colorectal cancer?
15% of patients develop cholangiocarcinoma
Risk is 4x higher than patients with IBD only, 10x higher than the general population.
When reporting pre-treatment rectal cancer staging on MRI, what are the components of the “DISTANCE” mnemonic?
DIS: Distance from the inferior part of the tumor to the transitional skin (anal verge).
T: staging
A: Anal complex involvement
N: Nodal staging
C: CRM (circumferential resection margin)
E: Extramural vascular invasion
What are the 3 areas that must be evaluated for staging of a low rectal tumour?
Muscularis propria/internal sphincter: Is there partial or full thickness invasion of the MP/IS? (Stage T1 (partial) vs T2 (full))
Is there extension into the intersphincteric plane? (Stage T3)
Is there extension into the external sphincter, levator or puborectal sling muscles? (Stage T4)
THIS STAGING IS SPECIFIC TO LOW RECTAL TUMOUR
What is the MRI lymph node staging classification in rectal cancer?
N0: No suspicious lymph nodes
N1: 1-3 suspicious lymph nodes
N2: >3 suspicious lymph nodes
TRUE OR FALSE
Diffusion weighted imaging allows differentiation between reactive and neoplastic lymphadenopathy in rectal cancer
FALSE
Helps in detection of lymph nodes but poor for differentiation between reactive and neoplastic lymphadenopathy.
What is the minimum distance required between the tumor and circumferential resection margin (mesorectal fascia) for surgical resection to remain indicated?
1mm or more from the CRM. If there is tumor, involved lymphadenopathy, tumor deposits or extramuscular vascular invasion within 1mm of the CRM, it is compromised.
In rectal cancer MRI staging, how do you subdivide T3A to T3D?
T3A: <1mm beyond muscularis propria
T3B: 1-5mm beyond muscularis propria
T3C: 5-15mm beyond muscularis propria
T3D: >15mm beyond muscularis propria
What is the differential diagnosis (causes) of medullary nephrocalcinosis?
Long DDX:
Furosemide abuse Hyperparathyroidism Medullary sponge kidney Sarcoidosis Renal tubular acidosis Sickle cell disease Renal papillary necrosis
Other hypercalcemic/hypercalciuric states (hypervitaminosis D, cushing syndrome, MM, hyperuricemia, etc.)
Infection (renal tuberculosis)
What is the differential diagnosis (causes) of cortical nephrocalcinosis?
Long DDX:
Renal cortical necrosis
chronic glomerulonephritis
Chronic pyelonephritis
Autosomal recessive polycystic kidney disease
Alport syndrome
vesicoureteral reflux
Nephrotoxic drugs
Infection in HIV patients
When assessing the enhancement pattern of thickened bowel wall, the presence of a double halo or target sign usually indicates what type of pathology?
They usually indicate an acute inflammatory or ischemic condition.
(inflammatory bowel disease, infection, radiation, vasculitis, ischemia)
The target sign in bowel thickening can be rarely seen in which neoplasm?
Infiltrating scirrhous carcinoma of the stomach and colon
In such cases, there will be bowel wall rigidity, severe luminal narrowing, abrupt transition and regional lymphadenopathy.
What is the DDx of a bulky exophytic bowel wall mass?
GIST
Metastases
Lymphoma
Name 2 bowel neoplasms that may display symmetric bowel wall thickening
Scirrhous carcinoma
Lymphoma
What is the DDx of bowel wall thickening in a segmental distribution (skip lesions)
Crohn’s disease
Infectious ileitis
Radiation enteritis
Ischemia
Less common:
Intramural hemorrhage
Lymphoma
Small bowel vasculitis (SLE)
What entity should be considered in a patient with AIDS, bowel wall thickening and adjacent high-attenuation (post-contrast) lymph nodes?
Kaposi’s sarcoma
What is the most commonly affected organ in IgG4-related disease?
Pancreas (type 1 autoimmune pancreatitis)
The bile ducts are the second most involved organ
What is the pathology of IgG4 related autimmune pancreatitis
Periductal infiltration by IgG4-positive plasma cells, which leads to periductal fibrosis.
When attempting to differentiate focal autoimmune pancreatitis from pancreatic cancer, what features of the main pancreatic duct help in differentiation?
Findings characteristic of autoimmune pancreatitis:
- Diffuse or segmental narrowing of the main pancreatic duct with no or mild duct dilatation
- Occasional CBD stenosis
- Penetration of the pancreatic duct through the mass (highly specific for benign stricture)
- Smooth tapered narrowing of the upstream pancreatic duct
- Lack of parenchymal atrophy
TRUE OR FALSE
Severe peripancreatic stranding is rare in autoimmune pancreatitis
TRUE
TRUE OR FALSE
Pancreatic calcifications and pseudocyst formation are rare in autoimmune pancreatitis
TRUE
allows differentiation with chronic alcoholic pancreatitis
What is the treatment of IgG4-related autoimmune pancreatitis?
Steroid therapy
What are the imaging findings in IgG4-related sclerosing cholangitis?
Focal or diffuse bile duct wall thickening
Biliary tree stenosis and upstream dilatation
Intrapancreatic portion of the CBD is the most commonly involved segment
What patient features help in the differentiation between primary sclerosing cholangitis and IgG4-related cholangitis?
Primary sclerosing cholangitis:
- younger patients
- associated with IBD
- more chronic symptoms
IgG4-related cholangitis:
- Older patients
- Frequently accompanied by pancreatic or extrapancreatic lesions
- may include obstructive jaundice
- often resolves with steroid therapy
On ERCP, features help in the differentiation between primary sclerosing cholangitis and IgG4-related cholangitis?
- Multifocal short intrahepatic biliary strictures with beaded appearance in PSC
- long and continuous strictures in IgG4
What are MR findings in IgG4-related sclerosing cholangitis?
- Circular and symmetric rind of tissue encasing the bile duct wall, with smooth margins
- Homogeneous enhancement on delayed phase
- Findings present in both stenotic and non-stenotic areas
- Gallbladder involvement occasionally occurs, diffuse wall thickening, T2hypo and late enhancement
What are the superior and inferior borders of the anal canal (surgical definition)?
Superior: Levator ani muscle
Inferior: anal verge
What seperates the internal and external anal sphincters?
the intersphinteric space. It is composed of loose fat-containing areolar tissue.
The vast majority (90%) of perianal fistulas are thought to arise secondary to what pathophysiology?
Impaired drainage of the anal glands (drained by the crypts of morgagni AKA anal sinuses) which leads to infection and perianal abscess
Give causes of perianal fistula other than anal gland obstruction (7)
crohn disease TB diverticulitis trauma anorectal cancer radiation therapy
Define grade 1 perianal fistula (St-Jame’s classification)
Intersphincteric fistula
Arises from the anal canal, penetrates the internal anal sphincter and extends caudally through the intersphincteric space to its cutaneous opening.
External sphincter and levator ani not involved
Define grade 2 perianal fistula (St-Jame’s classification)
Grade 1 fistula (intersphincteric) with intersphincteric abscess or secondary fistulous tract.
External sphincter and levator ani not involved
Define grade 3 perianal fistula (St-Jame’s classification)
Transphincteric fistula
Extends through both the internal and external sphincters and extends through the ischiorectal/ischioanal fossae in its way to its cutaneous opening
Define grade 4 perianal fistula (St-Jame’s classification)
Grade 3 fistula (transphincteric) with abscess or secondary tract (must not extend above the levator ani)
Define grade 5 perianal fistula (St-James classification)
Suprasphincteric fistula: perianal fistula with extension from the anal canal to above the levator ani
TRUE OR FALSE
Extra-sphincteric fistulas do not involve the internal or external anal sphincters and are typically caused by pelvic disease
TRUE
typical causes: crohn’s, diverticulitis, carcinoma
How can you differentiate an active from an inactive perianal fistula on MRI?
Active tract: T1 hypo, T2 hyper, enhances
Inactive tract: T1 hypo without T2 hyper and no enhancement
In what location do most perianal fistulas arise?
dentate line posteriorly
Describe the course of a St-James type 5 suprasphincteric perianal fistula
- Arises from anal canal
- Penetrates the internal sphincter
- Ascends within the intersphincteric space into the supralevator space
- Pierces the levator ani
- Descends through the ischiorectal fossae to its cutaneous opening
DDx of medullary nephrocalcinosis (mnemonic)
HAM HOP
Hyperparathyroidism Renal tubular Acidosis Medullary sponge kidney Hypercalcemia/hypercalciuria (cushing, multiple myeloma, bone mets) Oxalosis Papillary necrosis
DDx of cortical nephrocalcinosis (mnemonic)
COAG
Cortical necrosis
Oxalosis
Alport syndrome
Glomerulonephritis (chronic)
Also chronic pyelonephritis, rejected transplant, infection in HIV pts, etc.
What are the 3 most likely DDx of a T1 hyperintense adnexal mass?
Hemorrhagic functional ovarian cyst
Endometrioma
Mature cystic teratoma
Multiple adnexal cysts with high T1 signal and low T2 signal is specific for what diagnosis?
Endometrioma, >90% specificity
TRUE OR FALSE
Diffusion restriction of a gynecological lesion has a high positive predictive value for malignancy
FALSE
Several benign entities show diffusion restriction such as:
Hemorrhagic ovarian cyst
Endometrioma
Solid endometrial implants
Benign mature cystic teratoma
What underlying pathology (etiology) should be considered in a patient with hematosalpinx?
Endometriosis
The presence of T1 hyperintensity in a dilated fallopian tube is suggestive of endometriosis.
What is the most common cause of a dilated fallopian tube?
PID
Acute: pyosalpinx
Chronic: secondary to adhesions and scarring
Does not contain T1 hyperintense signal (in which case should consider endometriosis)
What are the MRI features of extraovarian endometriosis?
Solid nodules, often multiple
T2 hypo
Can contain punctate T1 hyper areas
Enhances on C+
Also important to assess for ant distortion of the pelvic anatomy that is suggestive of adhesions.
Associated tubal abnormality (hydro/hematosalpinx)
What are the MRI features for the diagnosis of a malignancy in an endometrioma?
Enhancing mural nodule (97% sensitive, 56% specific)
Loss of T2 shading in the endometriotic cyst
Mural nodule with diameter more than 3cm
Interval increase in size of endometrioma
What are the typical MRI features of cancers arising in extraovarian endometriosis?
Solid lesions
Intermediate T1 and T2 signal
Post-gado enhancement
Diffusion restriction
Not specific, benign endometriosis can enhance and have diffusion restriction.
TRUE OR FALSE
Contrast enhancement in extraovarian endometriosis is specific for malignant transformation
FALSE
Can be present in either benign endometriosis or after development of associated malignancy
What benign entities can produce an enhancing mural nodule in an endometrioma?
Inflammation
Decidual reaction of pregnancy
Polypoid endometriosis associated with exogenous hormone
Can mimic malignant transformation
When assessing a mural nodule in an endometrioma, what MRI characteristic allows you to differentiate decidual reaction of pregnancy from development of malignancy?
In decidual reaction of pregnancy, the mural nodules have a T2 signal hyperintensity similar to normal endometrium (compare to the uterus).
The mural nodules also regress post-partum
What is the differential diagnosis of a uterine mass arising in a postoperative scar (ex: c-section)?
Granuloma
Desmoid tumor
Benign endometriotic lesion
Primary/metastastic neoplasm
What MRI feature helps distinguish an endometrioma from a hemorrhagic ovarian cyst?
Shading sign
They are both T1 hyperintense
However, endometriomas have variable areas of T2 hypointensity (can involve the entire cyst), with a typical dependent layering configuration. Degree of decreased signal is variable, up to complete signal loss.
It is due to high concentration of iron/protein from recurrence hemorrhage.
Hemorrhagic cysts do not usually have T2 shading because they do not repeatedly bleed. Usually hyper T1 and T2
