Abstract Introduction Cancer cachexia is a multifactorial syndrome characterised by involuntary weight loss and muscle wasting, commonly seen in patients with advanced malignancies. Lean Body Mass (LBM) assessment is crucial for the early indentification and monitoring of cancer cachexia. Dual-energy X-ray absorptiometry (DEXA) is widely accepted as the gold standard for evaluating body composition. This study aims to develop a method for estimating LBM using whole-body low-dose CT acquired during PET/CT imaging. Methods A cohort of patients enrolled in a prospective pilot study on cancer cachexia were included in the analysis. All patients underwent both DEXA and 18 FFDG PET/CT imaging. Lean body mass was assessed by calculating the Total Body Lean Mass ratio (TBLMr) from DEXA (TBLMr DEXA ) and also whole-body low-dose CT (TBLMr CT ). Results A total of 32 (13-cachectic, 19-non-cachectic) patients with advanced malignancies were included in the analysis. The TBLMr CT and TBLMr DEXA were highly correlated (R 2 = 0.92). Bland-Altman plots indicated a scaling bias with increasing TBLMr DEXA values, with the non-cachectic group exhibiting a tighter distribution (0.06 ± 0.05) compared to the cachectic group (0.03 ± 0.11). TBLMr values were significantly different between cachectic and non-cachectic groups for both the DEXA-derived ( p < 0.004) and low-dose CT-derived ( p < 0.010) measurements. Conclusion Whole-body low-dose CT obtained from routine 18 FFDG PET/CT imaging can provide an accurate estimate of LBM, showing high concordance with DEXA-derived measurements and clinical diagnosis of cachexia. This method offers a practical method for monitoring cancer cachexia in patients undergoing routine 18 FFDG PET/CT scans.
O’Keefe et al. (Sat,) studied this question.