Validity Of Mri And Ultrasound Volume Measurements Of Foot Muscles With And Without Plantar Fasciopathy

Ultrasound (US) can potentially provide a more cost-efficient way to measure the volume of intrinsic foot muscles and plantar fascia (PF) without compromising accuracy. PURPOSE: to investigate the reliability of US and MRI in measuring the volume of intrinsic foot muscles and PF size. Second, to compare the validity of US to two volumetric calculations of MRI. METHODS: Intrinsic foot muscle volume and PF thickness were measured via US and MRI in 28 participants (females = 15, males = 13) (Age 54.6 +/- 6.63), with and without chronic plantar fasciitis (CPF) (with CPF = 13, without CPF = 15). The PF and flexor digitorum brevis (FDB) muscle were imaged via US and MRI. Subsequently, the PF thickness and FDB volume were calculated using the Osirix semi-auto volume segmentation software for MRI and the truncated cone formula for both MRI and US. Intraclass correlation coefficients (ICC), Pearson product correlation (r), minimal detectable difference (MDD), and standard error of the measurement (SEm) were calculated. RESULTS: High intra-class correlations (r = 0.989 - 0.997) were found for both MRI volume calculations: MRI Osirix semi-auto volume segmentation (MRI OX), and MRI truncated cone (MRI TC); as well as for the US volume calculation METHOD: ultrasound truncated cone (US TC). MRI OX and US TC were not statistically different from one another indicating that these measurements were comparable. MRI TC was significantly larger than both MRI OX and US TC. MRI OX’s relative MDD value is 4.89%, MRI TC value is 7.24%, and US TC value is 9.23% indicating that ultrasound had a lower level of precision compared to both MRI methods. CONCLUSIONS: US appears to be a valid method to calculate muscle volume for the FDB when compared to the MRI Osirix semi-auto volume segmentation. The TC method used for MRI data was found to be precise but not valid due to its consistent overestimation of volume. US may be used as an alternative to MR volumetric imaging when using Osirix auto-segmenting software.