Benjamin Matthew Howe MD, Presenter: Nothing to Disclose

Joel Patrick Felmlee PhD, Abstract Co-Author: Nothing to Disclose

Daniel Vance Litwiller, Abstract Co-Author: Nothing to Disclose

Jonathan T. Finnoff DO, Abstract Co-Author: Nothing to Disclose

Michael David Ringler MD, Abstract Co-Author: Nothing to Disclose

Kimberly Katz Amrami MD, Abstract Co-Author: Nothing to Disclose

To introduce axial balanced steady state free precession (bSSFP) MR imaging with provocative maneuvers as an adjunct test for popliteal artery entrapment syndrome (PAES).

All scans were performed on a 1.5 T scanner. An axial 2D bSSFP, non-fat saturated imaging technique was performed through both knees simultaneously with the following parameters: TR 3.2-8.2 ms, minimum TE (1.3-1.8 ms), flip angle 45º, field of view to include both knees (30-40 cm), 5 mm slice thickness with 0 skip, 224 pixel × 256 pixel matrix, and number of excitations 1. An 8 channel torso phased array coil was used in association with a Plexiglas footplate. bSSFP was performed in the neutral position and then in resisted plantar and dorsiflexion (Figure). All scans were performed and analyzed by a single fellowship trained musculoskeletal radiologist. A retrospective chart review was performed to identify patients who underwent additional diagnostic evaluation with provocative ultrasound (US) and/or conventional angiography.

One hundred and twenty legs were evaluated in 60 patients. A total of 22 extremities (11 patients) underwent conventional diagnostic angiography and/or subsequent surgical intervention. The positive predictive value (PPV) of provocative bSSFP was 100% with 14 true positives and no false positives. The negative predictive value (NPV) of bSSFP was 50% with 4 true negatives and 4 false negatives. Arterial US exams with provocative measures were evaluated independently with a PPV of 64% (7 true positives and 4 false positives.) There were no true negatives and 7 false negatives for arterial US. Eighteen extremities underwent both provocative bSSFP and arterial US prior to conventional provocative diagnostic angiography. The PPV of provocative bSSFP and US were 100% and 64%, respectively. The NPV of bSSFP was 67% in this subset of patients. There were 7 false negatives and no true negatives with US.

The bSSFP PPV in our study group was 100% compared with 64% for provocative arterial US. The bSSFP NPV was only 50%, but this was superior to provocative arterial US in our study group.

bSSFP may simplify the evaluation of patients with chronic exertional leg pain by identifying patients who may benefit from conventional diagnostic angiography to exclude PAES.

Howe, B, Felmlee, J, Litwiller, D, Finnoff, J, Ringler, M, Amrami, K, Balanced Steady-State Free Precession Imaging of Popliteal Artery Entrapment Syndrome.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006523.html