Quantification of popliteal artery narrowing with QISS MRA during active ankle plantarflexion in healthy, asymptomatic volunteers and its potential application in the diagnosis of popliteal artery entrapment syndrome (PAES).

OBJECTIVE

To assess the degree of narrowing of the popliteal artery during active ankle plantar flexion in healthy volunteers using a non-contrast quiescent-interval single-shot (QISS) magnetic resonance angiography (MRA) technique.

MATERIALS AND METHODS

Following IRB approval, 10 healthy volunteers were recruited and following informed consent underwent QISS MRA of the lower extremity at rest and during ankle plantarflexion. Two pediatric musculoskeletal radiologists independently reviewed MR images in random order and recorded a number of subjective and objective anatomic variables including branch pattern, proximity of vessel to bony structures, gastrocnemius bulk, and presence of accessory muscle. Arterial narrowing with plantarflexion was recorded by a subjective assessment of 3D reconstructions (negligible or non-negligible) and objectively by measuring the narrowest diameter during plantarflexion and at rest. Agreement between reader scores was assessed using the concordance correlation coefficient (CCC) for continuous variables, and kappa and the proportion of agreement for categorical variables.

RESULTS

Mean reduction in arterial diameter during plantar flexion was 17.1% (min 1.9%, max 64.1%, SD 16.7%) for reader 1 and 17.2% (min 1.7%, max 50.0%, SD 14.3%.) for reader 2 with high agreement between readers: CCC = 0.92 and CI = 0.82, 0.96. Arterial narrowing was described subjectively as "non-negligible" in 7/20 legs by reader 1 and 5/20 legs by reader 2 with proportion of agreement = 0.90, CI (0.77, 1.00).

CONCLUSION

We observed a wide range of popliteal arterial narrowing with plantarflexion in asymptomatic volunteers. Larger studies, for which QISS is well suited, may be invaluable for distinguishing physiologic from pathologic arterial narrowing in patients with suspected popliteal artery entrapment syndrome (PAES).