Relevant Anatomy and Embryology Fibropolycystic Disorders Anomalies may occur during the embryologic development of the ductal plate that surrounds the portal vein in fetal life. Depending on the stage of fetal development at which these defects occur, a variety of common and uncommon abnormalities of the liver and biliary tree may result, including congenital hepatic fibrosis, polycystic liver disease, Caroli disease , and biliary hamartomas .…

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KEY FACTS Imaging Spectrum of appearances on CT Solitary, well-defined, water density, unilocular cystic lesion – Thin wall with sharp interface to normal splenic tissue – No peripheral/intracystic enhancement or solid component Some cysts can have septations, trabeculations, thick wall, internal necrotic debris, or calcification – May have attenuation greater than simple fluid (due to hemorrhage or protein) – Thin eggshell calcification or thick, irregular peripheral…

KEY FACTS Terminology Dissemination of splenic tissue into ectopic locations following splenic rupture (either traumatic or iatrogenic) Imaging Can occur in virtually every compartment of body Most common in abdomen/pelvis (65% of cases) Usually located within peritoneal cavity (greater omentum, bowel serosa, parietal peritoneum, undersurface of diaphragm) Less common locations include thorax (usually after diaphragmatic rupture) and subcutaneous soft tissues MDCT: Multiple nodules or masses scattered…

KEY FACTS Terminology Global or segmental parenchymal splenic ischemia and necrosis caused by vascular occlusion Imaging Acute findings on CECT Diagnosis best made on portal venous-phase images due to heterogeneous arterial-phase enhancement Global infarction: Complete nonenhancement of spleen – ± cortical rim sign: Preserved enhancement of peripheral rim of spleen in massive infarction Segmental infarction: Wedge-shaped or rounded low-attenuation area usually at periphery of spleen –…

KEY FACTS Terminology Splenomegaly: Splenic enlargement caused by a number of different underlying disorders Hypersplenism: Syndrome consisting of splenomegaly and pancytopenia in which bone marrow is either normal or hyperreactive You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

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KEY FACTS Terminology Benign ectopic splenic tissue of congenital origin Imaging Most splenules located in or near splenic hilum or ligaments 20% are near or within pancreatic tail and can mimic pancreatic neuroendocrine tumor May also be in diaphragmatic, pararenal, and gastric sites CT: Same enhancement and attenuation as normal spleen Isodense to main spleen on noncontrast images Serpiginous enhancement on arterial phase Homogeneous enhancement on…

Embryology , Anatomy , and Physiology The spleen develops from the dorsal mesogastrium and usually rotates to the left, becoming fixed in the left subphrenic location by peritoneal reflections linking it to the diaphragm, abdominal wall, stomach (gastrosplenic ligament), and kidney (splenorenal ligament). It usually develops as 1 "fused" mass of tissue, but variations are common. One or more accessory spleens are found in up to…

KEY FACTS Imaging Multiplanar, contrast-enhanced CT (or PET/CT) is optimal imaging test Protocol advice Intravenous contrast for CT or MR Double contrast barium enema Lymphoma Bulky colonic mass; without colonic obstruction Preservation of fat planes Metastasis May mimic primary adenocarcinoma on imaging You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log…

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KEY FACTS Terminology Autosomal dominant genetic disorder characterized by formation of innumerable colonic adenomatous polyps at young age and increased risk for colonic and extracolonic tumors Imaging Imaging tests : Double-contrast barium studies of colon and upper GI tract (may be redundant with endoscopy) CT or MR (for abdominal tumors) Innumerable colonic filling defects or ring shadows ± extraintestinal lesions Adenomatous (± malignant) polyps in Colon…

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KEY FACTS Imaging Imaging is critical for detection, diagnosis, staging, and follow-up of colorectal carcinoma (CRC) Detection : CT colonography, plus stool analysis Complementary role with standard colonoscopy Early cancer: Sessile or pedunculated polyp Advanced cancer: "Saddle" or "apple core" lesion – Circumferential narrowing of bowel lumen, overhanging borders, mucosal destruction Staging : Helical CT ± MR Short segment (< 10 cm) asymmetric mural thickening & luminal narrowing…

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KEY FACTS Terminology Blunt or penetrating injury to rectum or colon Imaging Transverse and descending colon are most common sites for blunt traumatic injury Rectum is most common site for penetrating injury Best diagnostic clue Colonic wall thickening with adjacent mesenteric hemorrhage or ectopic gas Best imaging tool: CECT with multiplanar reformations Rectal and intravenous contrast for penetrating injuries CT signs Discontinuity or thickening of colonic…

KEY FACTS Terminology Enteric fistula : Abnormal connection between bowel and another epithelial-lined surface (e.g., bladder, vagina, skin) Enteric sinus tract : Blind-ending tract originating from bowel Imaging Fluoroscopy Fistulogram: Best modality for enterocutaneous fistulas Small bowel follow-through : Complementary to CT or MR enterography for Crohn's disease Contrast enema : Often definitive for colonic fistulas (to bladder, vagina, etc.) CT: Primary or complementary role Definitive…

KEY FACTS Terminology Ogilvie syndrome, colonic pseudoobstruction, adynamic ileus, functional obstruction Acute: Reversible, occurring with severe medical illness and major surgeries Chronic: Constipation, no etiology for ileus, and repeated obstructive symptoms You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

KEY FACTS Terminology Cecal volvulus : Rotational twist of right colon on its axis, resulting in progressive distention and potential ischemia Cecal bascule Cecum is distended and lumen narrowed by medial folding and displacement, without twist You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here