Magnetic Resonance Imaging in Proximal Venous Outflow Obstruction.

Background: Proximal venous outflow obstruction (PVOO) in the abdomen and pelvis is increasingly recognized as an important contributor to venous disease of the lower extremity. There are currently no guidelines regarding a noninvasive screening tool for PVOO, although magnetic resonance venography (MRV) is commonly used in many practices. The objective of this study was to determine the value and utility of MRV in diagnosis and screening for PVOO.

Methods: This retrospective study consisted of 46 consecutive patients, all of whom presented with signs and/or symptoms of PVOO and were evaluated with MRV followed by intravascular ultrasound (IVUS) and venography. Of these 46 patients suspected to have PVOO based on clinical evaluation, 24 patients had PVOO confirmed with IVUS and venography and PVOO was not observed on IVUS and venography in the remaining 22 patients. The MRV of these 46 patients was retrospectively reviewed in a blinded fashion and then correlated with IVUS and venography by 1 vascular surgeon. A scoring system was developed to define the types of radiography findings that were observed: normal, suspicious, and abnormal.

Results: When compared with IVUS and multiplane venography, the interpretation of MRV had a sensitivity of 100% and a specificity of 22.7%. The positive predictive value of MRV was 58.5%, and the negative predictive value was 100%.

Conclusions: The high sensitivity (100%) and low specificity (22.7%) of MRV suggest that it can be a screening tool at best, used only to rule out PVOO; it cannot be used to confirm PVOO, given its a 41.5% false positive rate. Thus, the development of a different, noninvasive diagnostic test that can more accurately assess patients with suspected PVOO during the initial evaluation of their lower-extremity venous disease should be explored.