Calcaneal attachment of the plantar fascia: MR findings in asymptomatic volunteers.

Abstract

To determine the spectrum of magnetic resonance (MR) imaging findings at the calcaneal attachment of the plantar fascia in asymptomatic volunteers. The study was approved by the institutional review board, and informed consent was obtained from all subjects. MR imaging was performed in 77 asymptomatic volunteers (mean age, 48.0 years; age range, 23-83 years) with use of a 1.5-T system. There were 40 women (mean age, 49.0 years; age range, 24-83 years) and 37 men (mean age, 48.0 years; age range, 23-83 years). Signal intensity characteristics and thickness of the medial, central, and lateral fascicles of the plantar fascia were assessed independently by two radiologists. The presence of soft-tissue edema, bone marrow edema, and bone spur formation at the attachment of the plantar fascia was noted. Datasets were analyzed with inferential statistic procedures. The mean thickness of the plantar fascia was 0.6 mm (medial fascicle), 4.0 mm (central fascicle), and 2.3 mm (lateral fascicle). Increased signal intensity in the plantar fascia was seen with the T1-weighted sequence in 16 of the 77 volunteers (21%), the T2-weighted sequence in six (7.8%), and the short inversion time inversion-recovery sequence in six (7.8%). Soft-tissue edema was seen deep to the plantar fascia in five of the 77 volunteers (6.5%) and superficial to the plantar fascia in 16 (21%). A calcaneal spur was detected in 15 of the 77 volunteers (19%). Calcaneal bone marrow edema was present in four volunteers (5.2%). T1-weighted signal intensity changes in the plantar fascia, soft-tissue edema superficial to the plantar fascia, and calcaneal spurs are common findings in asymptomatic volunteers and should be used with caution in the diagnosis of plantar fasciitis. Increased signal intensity within the plantar fascia with fluid-sensitive sequences is uncommon in asymptomatic volunteers.