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  1. 1. References: CT and MR imaging of whole abdomen John R. Haaga, MD, FACR
  2. 2.  Anatomy Role of imaging in Localization of pathology Neoplasms
  3. 3.  Posterior peritoneum Renal (Gerota’s) fasciae Lateroconal fascia Musculoaponeurotic plane, embracing the quadratus lumborum and psoas muscles, the diaphragmatic crura and associated ligamentous fascia.
  4. 4. Retroperitoneal spaces
  5. 5.  Iliopsoas compartment - located within and immediate adjacent to psoas muscle - posteromedial to the posterior pararenal space
  6. 6.  The retromesenteric, retrorenal, and lateroconal planes are potential routes of interfascial communication between the retroperitoneal spaces. Retroperitoneal hemorrhage or rapidly expanding fluid collections can spread via these interfascial connections.
  7. 7.  Largest Pancreas, Duodenum, Colon Continuous across the midline
  8. 8.  Smallest Continues anterolaterally into the properitoneal fat, the extraperitoneal fat of the anterior abdominal wall.
  9. 9.  Plain radiograph USG CT MRI
  10. 10. Pancreatic calcification Common  Rare - Chronic alcoholic - Idiopathic pancreatitis - Hereditary pancreatitis - Cystic fibrosis - Hyperparathyroidism - Protein malnutrition - Cystic tumours - Cavernous lymphangioma - Islet cell tumours - Haemangioma - Pseudo cysts - Haematoma
  11. 11.  Multidetector CT in retroperitoneal haemorrhages, fluid collections, AAA and masses. Magnetic resonance (MR) imaging has an increasing role in evaluating soft-tissue masses of the extraperitoneal spaces.
  12. 12.  Below the kidneys, the retroperitoneal spaces -a single space with direct contiguity between the anterior and posterior portions. Retroperitoneal hemorrhage or fluid spread from the abdominal retroperitoneum into the extraperitoneal pelvis along the anterior and posterior perirenal fasciae, which combine to form the fascial plane in the iliac fossa . Superiorly, the perirenal fasciae are attached to the diaphragm. On the right side, the bare area of the liver is directly connected to the anterior pararenal space. Therefore, hepatic lacerations involving the bare area of the liver can be a source (albeit uncommon) of retroperitoneal hemorrhage.
  13. 13.  CT findings of duodenal injury- duodenal wall thickening- periduodenal fluid- Fluid in the right anterior pararenal space- Diminished bowel wall enhancement of the injured segment- extraluminal air (More specific sign of duodenal perforation)- extraluminal oral contrast material air (More specific sign of duodenal perforation)- the “sentinel clot” sign
  14. 14.  Two-thirds of blunt pancreatic injuries occur in the pancreatic body, with the remainder occurring with equal frequency in the head, neck, and tail.
  15. 15.  Goals of imaging- to identify the retroperitoneal hemorrhage, its location and its possible source- to assess its relative stability on the basis of the size and presence (or absence) of active extravasation of intravascular contrast material
  16. 16. Surgical standpoint, the retroperitoneum can bedivided into zones because hematoma locationhas therapeutic implications
  17. 17.  Pelvic retroperitoneum is the most common location of retroperitoneal hemorrhage, frequently in association with pelvic fractures.
  18. 18.  In the setting of trauma should raise suspicion for- Pancreatic injury- Duodenal injury- Renal collecting system injury (with urine leakage)- Retroperitoneal hemorrhage
  19. 19.  Primary- Lymphoid malignancy : NHL, HL, HIV related NHL- Enlarged LNs in HIV- Soft tissue masses Secondary- Lymphnodes Testicular, Prostate- Metastases UB, Cervix etc..
  20. 20.  Lymphnodes1) Paracaval and paraortic : > 10 mm2) Retrocural : > 7 mm MRI has better distinction than CT between LNs and vessels and bowels
  21. 21.  NHL/HD Paraortic LN very frequent in NHL as compared to HDAnn Arbor staging
  22. 22.  Characterization of the Retroperitoneal Space Displacement of retroperitoneal organs strongly suggests that the tumor arises in the retroperitoneum Displacement of Major vessels and some of their branches
  23. 23.  Beak Sign: a mass deforms the edge of an adjacent organ into a “beak” shape, it is likely that the mass arises from that organ (beak sign)
  24. 24. Embedded Organ Sign.—When a tumor compresses anadjacent plastic organ (eg, gastrointestinal tract, inferiorvena cava) that is not the organ of origin.
  25. 25.  Phantom (Invisible) Organ Sign.—When a large mass arises from a small organ, the organ sometimes becomes undetectable. Prominent Feeding Artery Sign.— Hypervascular masses are often supplied by feeding arteries that are prominent enough to be visualized at CT or MR imaging, a finding that provides an important key to understanding the origin of the mass.
  26. 26.  Although the MR imaging appearance of most soft-tissue masses is nonspecific The presence of certain histologic components (eg, myxoid stroma, collagen fibers, calcification, and fat) can be suggested by evaluating intralesion signal intensity and enhancement patterns. Determination of the dominant histologic component can help narrow the differential diagnosis of the lesion. However, management changes a bit
  27. 27. Poorly differentiated liposarcoma
  28. 28.  Target Sign: a central area of low to intermediate signal intensity surrounded by a ring of high signal intensity on T2-weighted images Corresponds to fibrous tissue centrally and myxoid tissue peripherally and is commonly seen in neurofibroma and schwannoma
  29. 29. Neurofibroma
  30. 30.  Bowl of Fruit Sign: A mosaic of mixed low, intermediate, and high signal intensity on T2- weighted images as a result of admixture of solid components, cystic degeneration, hemorrhage, myxoid stroma, and fibrous tissue. This finding is commonly seen in malignant fibrous histiocytoma, synovial sarcoma, and Ewing sarcoma.
  31. 31. Malignant fibrous histiocytoma
  32. 32.  Proliferation of fibroblasts, infiltration of acute inflammatory cells, and proliferation of capillaries, surrounded by collagen fibers.
  33. 33.  Eitiology- Idiopathic (70 %) - Focal inflammatory or- Around AAAs infectious conditions- Medications e.g. - (e.g., diverticulosis, app methysergide, beta endicitis, extravasation blockers, methyldopa, h from the urinary tract). ydralazine, antibiotics, a - Previous surgery or nd some analgesics radiation treatment.- systemic infections - Trauma. (e.g., tuberculosis, syphi - Retroperitoneal lis, actinomycosis, bruce hemorrhage. llosis, fungal infections). - Marfans disease. - Inflammatow bowel disease
  34. 34.  Defined as focal area of dilatation of aortic diameter >3 cm Majority are infrarenal 2-20 %- juxtrarenal and pararenal Atherosclerotic/ degenerative- most common Other causes
  35. 35.  Inflammatory aneurysm (5-15 %) Results from fibrotic autoimmune reaction to atherosclerotic plaque Difficult surgical management
  36. 36.  Infected aneurysms More prone to rupture Increased periaortic fat earliest sign Irregularly shaped