Triple Phase CT May Replace Dual-energy X-ray Absorptiometry Scan For Evaluation of Osteoporosis in Liver Transplant Candidates.

BACKGROUND: Assessment of bone density is an important part of liver transplant (LT) evaluation for early identification and treatment of osteoporosis (OP). Dual-energy X-ray absorptiometry (DXA) is currently the standard clinical test for osteoporosis; however, it may contribute to the appointment burden on LT candidates during the cumbersome evaluation process and there are limitations affecting its accuracy. In this study, we evaluate the utility of biomechanical analysis of vertebral images obtained during triple phase dual-energy abdominal CT (TPCT) in diagnosing osteoporosis among LT candidates.

METHODS: Retrospective review of cases evaluated for liver transplant between 01/2017 and 03/2018. All patients who underwent dual-energy TPCT within 3 months of DXA were included. The biomechanical CT (BCT) analysis was performed at a centralized lab (O.N. Diagnostics, Berkeley, CA, USA), blinded to the DXA data. DXA-based osteoporosis was defined as T-score ≤ -2.5 at the hip or spine. BCT-based osteoporosis was defined as vertebral strength ≤ 4,500 N women or ≤ 6,500 N men, or trabecular volumetric bone mineral density ≤ 80 mg/cm3 .

RESULTS: Comparative data were available for 91 patients who had complete data for both DXA and BCT: (31 women, 60 men), mean (± SD) age 54 ± 11 years, mean body mass index 28 ± 6 kg/m2 . Using DXA as clinical reference, sensitivity of BCT to detect DXA-defined osteoporosis was 83.3% (20/24 patients) and negative predictive value was 91.7%; specificity and positive predictive value were 65.7%, 46.5%, respectively.

CONCLUSION: Biomechanical CT analysis of vertebral images on triple phase CT, routinely obtained during transplant evaluation, can reliably rule out osteoporosis in liver transplant candidates. Patients with suspicion of osteoporosis on TPCT may need further evaluation by DXA.