Assessment of Gluteus Maximus Muscle Area With Different Image Analysis Programs

Abstract

Wu GA, Bogie K. Assessment of gluteus maximus muscle area with different image analysis programs. Objective To determine the effectiveness of a percutaneous gluteal stimulation system (GSTIM) by comparing assessments of axial computed tomography (CT) scans for the pelvic area. Design Comparing the measurements of the cross-sectional area (CSA) of the gluteus maximus muscle between raters and 2 image analysis programs. Setting Retrospective axial CT scans of the pelvic area. Participants Men (N=9) with complete (below T6) spinal cord injury (SCI) and at least 2 years postinjury participated in the study (range, 29–75y; mean age, 51.8y). Intervention Comparing gluteus maximus CSA before and after a period of GSTIM. Main Outcome Measure Measurements made by 2 expert and 2 nonexpert raters were used to compare the repeatability and reliability of measuring muscle CSA. The longitudinal study presented is from repeated CT scans obtained over a 2-year period for 1 representative participant who received a GSTIM system. Results For repeatability, nonexpert raters measured a mean CSA of 35.2cm 2 (range, 20–45cm 2), while experts measured 21cm 2 (range, 10–35cm 2). A composite of all raters using the same program had SDs of 2.5 to 2.6cm 2 for a program available through the National Institutes of Health and 2.5 to 4.4cm 2 for a commercially available program. For reliability, differences between the 2 programs had mean differences in SD between 2.2 and 3.7cm 2. Conclusions The same rater and program (preferably the more reliable ImageJ) is recommended for the course of a longitudinal study. Otherwise, significant error would be introduced. Furthermore, significant increases in the CSA of gluteal muscle compared with preintervention (baseline) measurements were observed for the participant receiving GSTIM.