ARRS 2022 Abstracts

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E2144. Sonographic Evaluation of Primary Retroperitoneal Benign and Malignant Processes with CT and MRI Correlation
Authors
  1. Nadia Solomon; Yale University School of Medicine
  2. Douglas Katz; NYU Winthrop University Hospital
  3. Margarita Revzin; Yale University School of Medicine
Background
There is a broad spectrum of diseases and conditions that originate and are localized in the retroperitoneum and retroperitoneal (RP) spaces of the abdomen and pelvis. Although CT and MRI play an important role in characterization and assessment of the extent of the disease and involvement of adjacent and distant structures, ultrasound (US) often is the first imaging modality that detects retroperitoneal pathology in patients with unsuspected diagnosis. Familiarity with the US imaging features of various retroperitoneal masses will facilitate diagnosis and direct further management.

Educational Goals / Teaching Points
Teaching points include: 1) familiarize radiologists with retroperitoneal anatomy and spaces; 2) review role of ultrasound in evaluation of retroperitoneal disease; 3) discuss characteristic sonographic features of various retroperitoneal processes with CT and MRI correlation; 4) briefly discuss pitfalls in the diagnosis of retroperitoneal pathologies; and 5) provide a diagnostic algorithm and management of RP processes and the role of US surveillance in monitoring of the benign entities.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
This exhibit includes anatomy of RP and its spaces and the tole of US in evaluation of RP disease, including gray scale and color Doppler, image optimization, and imaging protocol, followed by sonographic features with correlative CT and MRI findings of various RP processes. The pathologies are divided into the following subcategories: a) fat composition (lipoma, liposarcoma, leiomyosarcoma, teratoma); b) vascular (AVM, AVF, hematoma, IVC leiomyosarcoma, angiosarcoma); c) nerve extension and foramina expansion (schwannoma, neurofibroma); d) cystic (post-traumatic cysts, pseudocysts (pancreatitis), dermoid, abscess, lymphngioma, cystadenoma, epidermoid cyst, cystic ganglioneuroma); e) calcifications (teratomas, angiosarcomas); f) necrosis (tumors with necrotic center including PEComas, liposarcomas, leiomyosarcoma, rhabdomyosarcoma); g) perivascular infiltrative process (retroperitoneal fibrosis, Erdheim-Chester disease and associated hydronephrosis, lymphoma, extramedullary hematopoiesis, amyloidosis); h) fibrosis, speculated margins(desmoid); and i) hormone secretion (paraganglioma, ganglioneuroma). The exhibit also contains pitfalls (solid organ RP masses) and an algorithmic approach to diagnosis will be provided to aid stratification of various RP pathologies into conservative or surgical management or biopsy.

Conclusion
Often US is the first imaging modality that detects RP pathology in patients with unsuspected diagnosis. Therefore, recognition of the key imaging features specific to various RP pathologies is essential in narrowing the differential diagnosis and are helpful in decision making regarding the next imaging modality of choice as well as for timely management of patients, especially pediatric patients. CT and MRI are excellent complimentary cross-sectional modalities that allow a better tissue and location assessment can provide a road map for biopsy in cases where the diagnosis cannot be achieved using imaging alone.