Plantar fascia evaluation with a low-field MRI scanner in weight-bering position: our initial experience in patients with plantar fasciitis and in healthy volunteers

Purpose: To assess the usefulness of weight-bearing examination of the ankle performed with a low-field MRI scanner in the evaluation of plantar fascia in normal healthy volunteers and in patients with a clinical evidence of plantar fasciitis. Methods and Materials: We retrospectively evaluated ankle MR examinations in two groups of 40 patients each, performed between January and July 2008. Spin echo T1W, Gradient echo T2W, and Short Tau Inversion Recovery (STIR) images were acquired with a 0.2 T scanner (G-Scan, Esaote Biomedica, Genoa, Italy) in both weight-bearing position and normal conventional supine position. A dedicated extremities transmitter/receiver coil was used. The lesion site and signal intensity changes were evaluated in consensus by three musculoskeletal experienced radiologists. Results: In all healthy volunteers, a normal appearance of plantar fascia was observed in both conventional supine and in weight-bearing positions. In the latter, an increased stretching of plantar fascia fibers was revealed. In patients with clinical evidence of plantar fasciitis, MRI performed in both positions confirmed the diagnosis in 35/40 cases. Only in the weight-bearing position a subtle plantar fascia rupture was also detected in 4/40 cases. In 5/40 cases the plantar fascia was normal in both positions, and there were other causes of heel pain such as Achilles tendinopathy, calcaneal spur, and calcaneal edema without plantar fascia involvement. Conclusion: Imaging the heel in weight-bearing position with a new developed MRI scanner is useful in demonstrating subtle ruptures of plantar fascia, which can be overlooked when imaging the ankle only in supine position.