MDCT signs differentiating retroperitoneal and intraperitoneal lesions- diagnostic pearls Poster No.: C-0987 Congress: ECR 2015 Type: Educational Exhibit Authors: D. V. Bhargavi, R. Avantsa, P. Kala; Bangalore/IN Keywords: Abdomen, CT, Diagnostic procedure, Education and training DOI: 10.1594/ecr2015/C-0987 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 35
Learning objectives The diagnosis of retroperitoneal lesions is challenging which includes lesions from the retroperitoneal organs and lesions outside the major organs. To differentiate and diagnose retroperitoneal lesions and Intraperitioneal lesions based on signs on MDCT. To demonstrate various signs on MDCT to differentiate lesions from the retroperitoneal organs and primary retroperitoneal lesions. To present an approach for the diagnosis of retroperitoneal lesions on MDCT. Background Introduction The retro peritoneum is the portion of the abdomen located posterior to the peritoneal cavity extending from the diaphragm to the pelvic inlet. It includes portions of the colon, duodenum, pancreas, kidneys, adrenal glands, abdominal aorta, inferior vena cava, lymph nodes, fat and much of the abdominal wall musculature. The retro peritoneum is commonly divided into three spaces by the anterior and posterior renal fasciae: 1. Anterior pararenal space 2. Perirenal space 3. Posterior pararenal space Psoas compartment is sometimes considered a fourth retroperitoneal space. The anterior, posterior and lateroconal fasciae are often not seen as distinct layers but instead as a multilayered complex, hence the localization of the lesion into specific compartments is sometimes difficult. The computed tomography can demonstrate important characteristics of these tumors. Even then the diagnosis is often challenging for radiologists. Diagnostic challenges include precise localization of the lesion, organ of origin, determination of the extent of invasion, and characterization of the specific pathologic type. Page 2 of 35
Retroperitoneal lesions can either from the retroperitoneal organs or primary retroperitoneal lesions. Primary retroperitoneal mass lesions are a diverse group of lesions that arise within the retroperitoneum but outside the major organs. Images for this section: Fig. 1: sectional anatomy of normal Retroperitoneal structures, fascial planes and spaces. Page 3 of 35
Fig. 2: Normal sectional anatomy of Retroperitoneum. Fig. 3: Line diagram of Retroperitoneal structures, fascial planes and spaces. Page 4 of 35
Fig. 4: Axial CECT images at different levels showing normal Retroperitoneal structures. Page 5 of 35
Findings and procedure details We retrospectively studied 25 patients with abdominal mass lesions and subsequently confirmed with surgical and histopathological diagnoses of retroperitoneal and intraperitoneal (IP) mass lesions. The cases included were retroperitoneal sarcomas, renal cell carcinoma, suprarenal lesions, mesenteric mass and GIST. Approach to retroperitoneal (RP) lesions: Step 1. Intraabdominal or Retroperitoneal (figure 5) Ø The retroperitoneal lesion due to its location tends to show mass effect on the adjacent retroperitoneal structures. Ø Lateral or anterior displacement of the retroperitoneal structures or compression over the retroperitoneal structures. Case 1 (figure 6) A 35 year old male presented with abdominal mass. There is displacement of the superior mesenteric vessels. The lesion is identified as right renal mass and was pathologically proven to be a RCC. Case 2 (figure 7) A 42 year old male patient with a mass in the left posterior pararenal space displacing the left kidney anteromedially. The mass was diagnosed as retroperitoneal sarcoma. Case 3 (figure 8) A 55 years old patient with left lower pole renal cell carcinoma showing displacement of the ascending colon anteriorly. Case 4 (figure 9) The pancreas is seen displaced anteriorly by the prevertebral mass in a 40 year old female patient which was diagnosed as retroperitoneal lymphoma. Case 5 (figure 10) Page 6 of 35
The pancreatic tail mass lesion displacing the ascending colon anteriorly. Case 6 (figure 11) Psoas mass lesion seen displacing the aorta anteriorly. Step 2 - Primary retroperitoneal lesions (figure 12) Primary retroperitoneal lesions are the lesions within the retroperitoneum but outside the retroperitoneal structures. Ø They have to be suspected if the lesion is displacing the retroperitoneal structures anteriorly Ø According to the pattern of the spread like encasement of the aorta, growth along the paraspinal region and along the normal structures. Pattern of spread and Infiltration of the retroperitoneal structures Case 7 (figure 13) Sagittal CT image of a 35 year old male patient with retroperitoneal lymphoma demonstrating encasement and infiltration of the inferior vena cava by the mass. Case 8 (figure 14) Sagittal CT image of a 35 year old male patient with retroperitoneal lymphoma demonstrating encasement of the right ureter. Case 9 (figure 15) Retroperitoneal mass lesion seen encasing and infiltrating the left ureter causing left hydroureteronephrosis. Floating aorta sign: Floating aorta sign: encasement of aorta by retroperitoneal mass. Case 10 (figure 16) A 38 years old male patient with retroperitoneal lymphoma showing encasement of the aorta by the retroperitoneal mass. Step 3-Retroperitoneal lesions from retroperitoneal structures. (figure 17) Page 7 of 35
There are four different signs on MDCT which aid in identifying the origin of the lesion. Ø Beak sign: Beak deformation of edge of adjacent organ Ø Phantom organ sign: Obscuration of small organs by large mass. Ø Embedded organ sign: Part of organ of origin is embedded in the mass with adjacent desmoplastic reaction. Ø Prominent feeding artery sign: Feeding artery to the lesion arises from the organ of origin. Beak sign Case 11 (figure 18) Axial CT image of left renal cell carcinoma demonstrating beak shaped deformation at the edge of the left kidney. Case 12 (figure 19) Beak sign demonstrated in a case of pancreatic tail mass lesion. Case 13 (figure 20) Sagittal CT image demonstrating beak sign in case of renal cell carcinoma. Phantom organ sign Case 14 (figure 21) Axial CT image of a case of pheochromocytoma. Left adrenal gland is not visualized. Embedded organ sign Case 15 (figure 22) Axial CT image of right renal cell carcinoma showing compression of the right kidney by the mass. The right kidney appears embedded within the mass with desmoplastic reaction at the contact surface. Case 16 (figure 23) Page 8 of 35
Sagittal CT image of a case of left psoas abscess demonstrating embedded organ sign Prominent feeding artery sign Case 17 (figure 24) Axial CT image of right renal cell carcinoma showing the mass being supplied by the right renal artery. Case 18 (figure 25) The retroperitoneal pancreatic mass showing its arterial supply from the celiac artery. Step 4-Intraperitoneal lesions (figure 26) Points aid in diagnosis of intraperitoneal lesions Ø Identifying organ of origin Ø Mass effect on the adjacent structures Ø Growth within the peritoneal cavity Ø Posterior displacement of the retroperitoneal structures. Case 19 (figure 27) A 42 year old patient with gastrointestinal stromal tumour with mass effect on intraperitoneal structures- spleen, small bowel, liver. Case 21 (figure 28) Coronal and Sagittal CT images of a mesenteric mass within peritoneal cavity, anterior to aorta, IVC and mass effect on urinary bladder and small bowel. Case 22 (figure 29) Axial and sagittal CT images of a mesenteric mass lesion deforming the shape of liver and causing posterior displacement of aorta and kidney. Flowchart to approach the retroperitoneal/intraperitoneal lesions. (figure 30) Page 9 of 35
Images for this section: Fig. 5: Step 1. identify the lesion whether it is Intra-abdominal or Retroperitoneal. Page 10 of 35
Fig. 6: Axial CECT image in arterial phase demonstrating displacement of the superior mesenteric vessels by the right renal mass. Page 11 of 35
Fig. 7: Axial CECT image showing a mass in the left posterior pararenal space displacing the left kidney anteromedially. Page 12 of 35
Fig. 8: Thin section axial CT images showing displacement of the ascending colon anteriorly by a mass in the left kidney lower pole. Page 13 of 35
Fig. 9: Axial CECT image showing pancreas displaced anteriorly by the prevertebral mass. Page 14 of 35
Fig. 10: Axial CECT image showing the pancreatic tail mass lesion displacing the ascending colon anteriorly. Page 15 of 35
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Fig. 11: Sagittal CECT image showing Psoas mass lesion displacing the aorta anteriorly. Fig. 12: Step 2 - Identifying Primary Retroperitoneal lesions. Page 17 of 35
Fig. 13: Sagittal CECT image demonstrating encasement and infiltration of the inferior vena cava by the mass Page 18 of 35
Fig. 14: Axial CECT image demonstrating encasement and infiltration of the right ureter by the mass. Page 19 of 35
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Fig. 15: Oblique sagittal CECT image demonstrating encasement and Infiltration of the left ureter by the mass causing left hydroureteronephrosis. Fig. 16: Axial CECT images showing encasement of the aorta by the retroperitoneal mass Page 21 of 35
Fig. 17: Step 3-Identifying retroperitoneal lesions arising from retroperitoneal structures. Page 22 of 35
Fig. 18: Axial CECT image of left renal cell carcinoma demonstrating beak shaped deformation at the edge of the left kidney. Page 23 of 35
Fig. 19: Axial CECT image with beak sign demonstrated in a case of pancreatic tail mass lesion. Page 24 of 35
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Fig. 20: Sagittal CECT image demonstrating beak sign in case of renal cell carcinoma. Fig. 21: Axial CECT image of a case of Pheochromocytoma. Left adrenal gland is not visualized. Page 26 of 35
Fig. 22: Axial CECT image of right renal cell carcinoma showing compression of the right kidney by the mass. The right kidney appears embedded within the mass with desmoplastic reaction at the contact surface. Page 27 of 35
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Fig. 23: Oblique sagittal CECT image of a case of left psoas abscess demonstrating embedded organ sign. Fig. 24: Axial CECT image of right renal cell carcinoma showing the mass being supplied by the right renal artery. Page 29 of 35
Fig. 25: Axial CECT image showing the retroperitoneal mass being supplied by the celiac artery. Page 30 of 35
Fig. 26: Step 4-Identifying Intraperitoneal lesions Fig. 27: Coronal and sagittal CECT images showing mass effect on intraperitoneal structures- spleen, small bowel, liver. Page 31 of 35
Fig. 28: Coronal and Sagittal CECT images of a mesenteric mass within peritoneal cavity, anterior to aorta, IVC and mass effect on urinary bladder and small bowel. Fig. 29: Axial and sagittal CECT images of a mesenteric mass lesion deforming the shape of liver and causing posterior displacement of aorta and kidney. Page 32 of 35
Fig. 30: Flow chart-approach for diagnosis of intraperitoneal/retroperitoneal lesions. Page 33 of 35
Conclusion Reliable differentiation between intra and retroperitoneal lesions can be made using a specific approach pattern and various MDCT signs. Personal information Dr Vidya Bhargavi, Resident, Department of radiology, Vydehi institute of medical sciences, Bangalore, India. Dr Rohini Avantsa, MD. Sectional Imaging Division, Department of radiology, Vydehi institute of medical sciences, Bangalore, India. rkgayatri5@gmail.com Dr Prachi Kala, MD. Sectional Imaging Division, Department of radiology, Vydehi institute of medical sciences, Bangalore, India. References 1.Mzuki Nshino, Katsumi Hayakama, Manabu Minami, et al. Primary retroperitoneal neoplasms: CT and MR imaging findings with anatomic and pathologic diagnostic clues. Radiographics 2003; 23:45-57. Page 34 of 35
2- Engelken, Ros, Retroperitoneal MR imaging. Magnetic resonance imaging clin N Am 1997; 5:165-178. 3-Scanlan DB. Primary retroperitoneal tumour. J Urol 1959;81:740 Page 35 of 35