Iliopsoas compartment - located within and immediate adjacent to psoas muscle - posteromedial to the posterior pararenal space
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.
Largest Pancreas, Duodenum, Colon Continuous across the midline
Smallest Continues anterolaterally into the properitoneal fat, the extraperitoneal fat of the anterior abdominal wall.
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.
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.
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
Two-thirds of blunt pancreatic injuries occur in the pancreatic body, with the remainder occurring with equal frequency in the head, neck, and tail.
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
Surgical standpoint, the retroperitoneum can bedivided into zones because hematoma locationhas therapeutic implications
Pelvic retroperitoneum is the most common location of retroperitoneal hemorrhage, frequently in association with pelvic fractures.
In the setting of trauma should raise suspicion for- Pancreatic injury- Duodenal injury- Renal collecting system injury (with urine leakage)- Retroperitoneal hemorrhage
Primary- Lymphoid malignancy : NHL, HL, HIV related NHL- Enlarged LNs in HIV- Soft tissue masses Secondary- Lymphnodes Testicular, Prostate- Metastases UB, Cervix etc..
Lymphnodes1) Paracaval and paraortic : > 10 mm2) Retrocural : > 7 mm MRI has better distinction than CT between LNs and vessels and bowels
NHL/HD Paraortic LN very frequent in NHL as compared to HDAnn Arbor staging
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
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)
Embedded Organ Sign.—When a tumor compresses anadjacent plastic organ (eg, gastrointestinal tract, inferiorvena cava) that is not the organ of origin.
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.
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
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
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.