Objective:To investigate the feasibility of areal bone mineral density (aBMD) quantification and the diagnostic performance for abnormal bone mass using the coronal spectral localizer radiography (SLR) from photon-counting detector CT (PCD-CT).Methods:This cross-sectional study prospectively enrolled 67 participants who underwent both dual-energy X-ray absorptiometry (DXA) and dual-source PCD-CT examinations within 7 days at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between April 2024 and September 2025. The aBMD values of L1-L4 derived from DXA and calculated based on PCD-CT SLR were obtained (aBMD DXA and aBMD SLR, respectively). Participants were categorized into four groups based on body mass index (BMI): underweight (BMI<18.5 kg/m2, n=3), normal weight (18.5 kg/m2≤BMI<24 kg/m2, n=33), overweight (24 kg/m2≤BMI<28 kg/m2, n=22), and obese (BMI≥28 kg/m2, n=9) groups. Using aBMD DXA as the golden reference, T-scores were calculated, and participants were classified into normal bone mass (T-score≥-1.0, n=42), osteopenia (-2.50.05). Across the normal bone mass, osteopenia, and osteoporosis groups, significant differences were found in aBMD DXA, aBMD SLR, and AE ( P<0.001), but not in RAE ( P=0.426). Using aBMD SLR-based T-score classification, 38, 16, and 13 participants were classifying as having normal bone mass, osteopenia, and osteoporosis. For diagnosing osteoporosis, aBMD SLR achieved an accuracy of 94.0% (63/67), sensitivity of 90.9% (10/11), and specificity of 94.6% (53/56). For detecting abnormal bone mass, the accuracy, sensitivity, and specificity were 94.0% (63/67), 100% (25/25), and 90.5% (38/42), respectively. Conclusions:Quantitative bone density assessment based on PCD-CT SLR is feasible and accurate, unaffected by body habitus or bone mass status, and demonstrates high diagnostic performance for osteoporosis and abnormal bone mass.

Objective:To investigate the feasibility of areal bone mineral density (aBMD) quantification and the diagnostic performance for abnormal bone mass using the coronal spectral localizer radiography (SLR) from photon-counting detector CT (PCD-CT).Methods:This cross-sectional study prospectively enrolled 67 participants who underwent both dual-energy X-ray absorptiometry (DXA) and dual-source PCD-CT examinations within 7 days at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between April 2024 and September 2025. The aBMD values of L1-L4 derived from DXA and calculated based on PCD-CT SLR were obtained (aBMD DXA and aBMD SLR, respectively). Participants were categorized into four groups based on body mass index (BMI): underweight (BMI<18.5 kg/m2, n=3), normal weight (18.5 kg/m2≤BMI<24 kg/m2, n=33), overweight (24 kg/m2≤BMI<28 kg/m2, n=22), and obese (BMI≥28 kg/m2, n=9) groups. Using aBMD DXA as the golden reference, T-scores were calculated, and participants were classified into normal bone mass (T-score≥-1.0, n=42), osteopenia (-2.50.05). Across the normal bone mass, osteopenia, and osteoporosis groups, significant differences were found in aBMD DXA, aBMD SLR, and AE ( P<0.001), but not in RAE ( P=0.426). Using aBMD SLR-based T-score classification, 38, 16, and 13 participants were classifying as having normal bone mass, osteopenia, and osteoporosis. For diagnosing osteoporosis, aBMD SLR achieved an accuracy of 94.0% (63/67), sensitivity of 90.9% (10/11), and specificity of 94.6% (53/56). For detecting abnormal bone mass, the accuracy, sensitivity, and specificity were 94.0% (63/67), 100% (25/25), and 90.5% (38/42), respectively. Conclusions:Quantitative bone density assessment based on PCD-CT SLR is feasible and accurate, unaffected by body habitus or bone mass status, and demonstrates high diagnostic performance for osteoporosis and abnormal bone mass.