Quantitative ultrasound of the calcaneus in long-term liver or cardiac transplantation patients.

Bone loss is one of the most common complications after solid-organ transplantation, but it is frequently under-diagnosed. Our purpose was to evaluate quantitative ultrasound of calcaneus (QUS) in comparison with dual-energy X-ray absorptiometry (DXA) to identify transplant recipients with osteoporosis. We have cross-sectionally evaluated 140 transplant recipients (85 liver and 55 cardiac transplantations; mean age: 53.6 years, time since transplantation: 67.9 months). Devices used were Hologic 4500 QDR for DXA measurements and Sahara Clinical Sonometer (Hologic Inc, Bedford, MA) for calcaneal QUS. Quantitative ultrasound index (QUI) was calculated from speed of sound (m/s) and broadband ultrasonic attenuation (dB/MHz). QUI T-score and bone mineral density (BMD) T-score (spine and hip) were obtained from Spanish normative data. According to World Health Organization criteria, defined either at lumbar spine or femoral neck, 61% of the females had osteopenia and 32% had osteoporosis, whereas 52% of the males had osteopenia and 11% had osteoporosis. Calcaneal QUS parameters (speed of sound, broadband ultrasonic attenuation, and QUI) were positively correlated with lumbar and femoral BMD (p<0.001). In receiver operator characteristic analysis, a T-score QUI<or=-1.4 standard deviation (SD) had 68% sensitivity and 72% specificity for osteoporosis diagnosis by DXA criteria. However, to obtain maximal sensitivity (5% of false-negative), QUI T-score cutoff should be -0.6 SD, but specificity drops to 42%. In conclusion, a positive correlation exists between lumbar and femoral BMD and QUS parameters in long-term liver or cardiac transplant recipients. QUS could be recommended for screening of osteoporosis in long-term transplanted patients.