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Background: Peripheral quantitative computed tomography (pQCT) provides real volumetric bone density values, not only of the total, but also of trabecular and cortical bone, separately. In addition, it provides data on bone geometry that can be related to the risk of fracture. Methods: Total, cortical, and trabecular volumetric bone mineral densities (BMD), as well as the main geometric parameters (cross-sectional area, cortical area, trabecular area, and cortical thickness) were assessed by pQCT at the distal radius in 24 hemodialysis patients affected by severe secondary hyperparathyroidism (PTH, mean ± SD: 1444 ± 695 pg/mL). The strength-strain index (SSI), a biomechanical parameter describing bone fragility, was also determined. Results: Compared with a control group of 64 healthy age-matched subjects, volumetric BMD (mg/cm3 ) was significantly reduced in all patients (total BMD: 243 ± 87 vs. 405 ± 138, cortical BMD: 605 ± 218 vs. 856 ± 204, trabecular BMD: 95 ± 51 vs. 182 ± 75). Cortical area and cortical thickness showed significant modifications, while cross-sectional area did not. SSI was significantly reduced (547 ± 125 vs. 927 ± 306 mm3 ). PTH levels showed a significant inverse correlation with cortical BMD (r = -0.56), cortical thickness (r = -0.46), cortical area (r = -0.61), and SSI (r = -0.54). Quantitative analysis of bone demonstrated cortical porosity. Conclusions: In dialysis patients with severe secondary hyperparathyroidism, pQCT showed a significant cortical osteopenia, associated with geometric and mechanical bone impairment. Interestingly, we also found a comparable deficit of trabecular bone, which may be related to the very high PTH levels. Generalized cortical thinning, intracortical porosity and cortical-endosteal resorption (“trabecularization” of the cortical bone) are major determinants of reduced bone strength, which may be quantitated by pQCT. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to evaluate the relationship between myocardial viability (MV) detected by Tl-201 rest/redistribution protocol (RR-SPECT) and the presence of ventricular late potentials (VLPs) in acute myocardial infarction (AMI). We analyzed signal-averaged ECGs (SAECGs) in 28 patients (age 57 ± 10 years) with a first anterior AMI within 48 hours of symptoms (SAECG1) and prior to discharge (SAECG2). VLPs were defined according to the presence of filtered QRS (QRS-D) > 114 ms and duration of low amplitude signals (LAS) a 30 ms or root mean square voltage (RMS40) < 25 μ;V, using a 25-Hz filter, or a duration of LAS > 39 ms or RMS40 < 20 μ;V, using a 40-Hz filter. RR-SPECT was performed 17 ± 6 days after AMI. Segments were considered viable when counts were > 60% in early images or when a fill-in > 10% was detectable on delayed images of those segments with a first count between 31% and 59%. Methods: Patients were divided into two groups: with MV (group 1 = 16 patients) if almost one third of segments appeared to be viable; without MV (group 2 = 12 patients). No difference was found between the two groups in SAECG1, whereas, using a 25-Hz filter, a greater QRS-D (106.6 ± 13.5 vs 93.5 ± 6 ms) and LAS (31.2 ± 8.7 vs 18.1 ± 6.4 ms) as well as a smaller RMS40 (43 ± 33.5 vs 71.3 ± 30.4 μ;V) characterized the SAECG2 of group 1. Sensitivity and specificity of VLPs in detecting MV were 31% and 100%. When using cut-off values derived from median distribution of the population (QRS-D & 99 ms, LAS a 24 ms and RMS40 > 51 μ;V), sensitivity raised to 75% and specificity was 92% with a positive and negative predictive value of 92% and 73%. Conclusions: The presence of MV is associated with a greater incidence of VLPs. SAECG performed at the time of discharge may facilitate the identification of patients with μ;V after anterior AMI. [ABSTRACT FROM AUTHOR]