Muscle fat fraction in XXXX : dual-echo dual-flip-angle spoiled gradient-recalled MR imaging technique for quantification--a feasibility study.

@entity31181 @entity1 @entity4094
PURPOSE: To prospectively evaluate the muscle fat fraction (MFF) measured with dual-echo dual-flip-angle spoiled gradient-recalled acquisition in the steady state ( @entity31181 ) magnetic resonance (MR) imaging technique by using muscle biopsy as the reference standard. MATERIALS AND METHODS: After ethics approval, written informed consent from all @entity1 was obtained. Twenty-seven consecutive @entity1 , evaluated at the @entity4094 Center with a possible diagnosis of @entity4094 , were prospectively studied with MR imaging of the lower extremities to quantify muscle fatty infiltration by means of MFF calculation. Spin-density- and T1-weighted fast @entity31181 in-phase and opposed-phase dual-echo sequences were performed, respectively, with 20   and 80   flip angles. Round regions of interest were drawn by consensus on selected MR sections corresponding to anticipated biopsy sites. These were marked on the @entity1 's skin with a pen by using the infrared spider light of the system, and subsequent muscle biopsy was performed. MR images with regions of interest were stored on a secondary console where the MFF calculation was performed by another radiologist blinded to the biopsy results. MFFs calculated with dual-echo dual-flip-angle @entity31181 MR imaging and biopsy were compared by using a paired t test, Pearson correlation coefficient, and Bland-Altman plots. P value of < .05 was considered to indicate a statistically significant difference. RESULTS: The mean MFFs obtained with dual-echo dual-flip-angle @entity31181 MR imaging and biopsy were 20.3% (range, 1.7%-45.1%) and 20.6% (range, 3%-46.1%), respectively. The mean difference, standard deviation of the difference, and t value were -0.3, 1.3, and -1.3 (P > .2), respectively. The Pearson correlation coefficient was 0.995; with the Bland-Altman method, all data points were within the    2 SDs limits of agreement. CONCLUSION: The results show that dual-echo dual-flip-angle @entity31181 MR imaging technique provides reliable calculation of MFF, consistent with biopsy measurements.
