Pelvis Magnetic Resonance Imaging to Diagnose Familial Partial Lipodystrophy

Context The diagnosis of familial partial lipodystrophy (FPLD) is currently made based on clinical judgment. Objective There is a need for objective diagnostic tools that can diagnose FPLD accurately. Methods We have developed a new method that uses measurements from pelvic magnetic resonance imaging (MRI) at the pubis level. We evaluated measurements from a lipodystrophy cohort (n = 59; median age [25th-75th percentiles]: 32 [24-44]; 48 females and 11 males) and age- and sex-matched controls (n = 29). Another dataset included MRIs from 289 consecutive patients. Results Receiver operating characteristic curve analysis revealed a potential cut-point of <= 13 mm gluteal fat thickness for the diagnosis of FPLD. A combination of gluteal fat thickness <= 13 mm and pubic/gluteal fat ratio >= 2.5 (based on a receiver operating characteristic curve) provided 96.67% (95% CI, 82.78-99.92) sensitivity and 91.38% (95% CI, 81.02-97.14) specificity in the overall cohort and 100.00% (95% CI, 87.23-100.00) sensitivity and 90.00% (95% CI, 76.34-97.21) specificity in females for the diagnosis of FPLD. When this approach was tested in a larger dataset of random patients, FPLD was differentiated from subjects without lipodystrophy with 96.67% (95% CI, 82.78-99.92) sensitivity and 100.00% (95% CI, 98.73-100.00) specificity. When only women were analyzed, the sensitivity and the specificity was 100.00% (95% CI, 87.23-100.00 and 97.95-100.00, respectively). The performance of gluteal fat thickness and pubic/gluteal fat thickness ratio was comparable to readouts performed by radiologists with expertise in lipodystrophy. Conclusion The combined use of gluteal fat thickness and pubic/gluteal fat ratio from pelvic MRI is a promising method to diagnose FPLD that can reliably identify FPLD in women. Our findings need to be tested in larger populations and prospectively.