Validity of skeletal muscle mass index measurements for assessing sarcopenia in patients with gynecological cancer

Background: The current study investigated an optimal method for using CT scan in detection of low skeletal muscle mass quantity (SMQ). Methods: In total, 82 consecutive patients with gynecological cancers were examined using computed tomography (CT) and dual-energy X-ray absorptiometry (DEXA) before treatment. Low SMQ was defined as a DEXA-based skeletal muscle mass index (SMI) of <5.40 kg/m(2). Furthermore, CT-based SMI values were measured by six evaluators, and each evaluator measured SMI values two times for each subject. The first SMI value and the average SMI value were used for analyses. Receiver operating characteristic (ROC) analyses were performed to evaluate the performance of CT-based SMI measurements for detecting low SMQ. Interobserver agreement was assessed using the intraclass correlation coefficient (ICC). Results: In total, 23 patients (28.0%) were diagnosed with low skeletal muscle mass. All areas under the curve (AUC) values from twelve (six evaluators x two measurements) ROC curves were within the range of 0.8-0.9. AUC values based on a single measurement and those based on two measurements were almost the same. The ICC was 0.828 (95% CI 0.777-0.874, P < 0.001) when using a single measurement value and increased to 0.959 (95% CI 0.944-0.971, P < 0.001) when using the average of the two measurements. Conclusions: A single measurement CT-based SMI efficiently identified patients with low SMQ in a daily clinical setting. The reliability of SMI measurements might be further improved by using a mean value of two measurements compared with the use of a single measurement value.