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Background: Dual-source dual-energy computed tomography (DECT) offers the potential for opportunistic osteoporosis screening by enabling phantomless bone mineral density (BMD) quantification. This study sought to assess the accuracy and precision of volumetric BMD measurement using dual-source DECT in comparison to quantitative CT (QCT). Methods: A validated spine phantom consisting of three lumbar vertebra equivalents with 50 (L1), 100 (L2), and 200 mg/cm3 (L3) calcium hydroxyapatite (HA) concentrations was scanned employing third-generation dual-source DECT and QCT. While BMD assessment based on QCT required an additional standardised bone density calibration phantom, the DECT technique operated by using a dedicated postprocessing software based on material decomposition without requiring calibration phantoms. Accuracy and precision of both modalities were compared by calculating measurement errors. In addition, correlation and agreement analyses were performed using Pearson correlation, linear regression, and Bland-Altman plots. Results: DECT-derived BMD values differed significantly from those obtained by QCT (p < 0.001) and were found to be closer to true HA concentrations. Relative measurement errors were significantly smaller for DECT in comparison to QCT (L1, 0.94% versus 9.68%; L2, 0.28% versus 5.74%; L3, 0.24% versus 3.67%, respectively). DECT demonstrated better BMD measurement repeatability compared to QCT (coefficient of variance < 4.29% for DECT, < 6.74% for QCT). Both methods correlated well to each other (r = 0.9993; 95% confidence interval 0.9984–0.9997; p < 0.001) and revealed substantial agreement in Bland-Altman plots. Conclusions: Phantomless dual-source DECT-based BMD assessment of lumbar vertebra equivalents using material decomposition showed higher diagnostic accuracy compared to QCT.
Recent studies have reported that takotsubo syndrome (TTS) patients are suffering from life-threatening arrhythmias. The aim of our study was to understand the short and long-term usefulness of cardiac implantable electronic devices in TTS patients.We constituted a collective of 142 patients in a bi-centric study diagnosed with TTS between 2003 and 2017. The patient groups, divided according to the treatment with (n = 9, 6.3%) or without cardiac devices (n = 133, 93.7%), were followed-up to determine the importance of devices and its complications. One patient was treated with a permanent pacemaker, five patients with a wearable cardioverter defibrillator, two patients with a subcutaneous defibrillator and one patient with a transvenous defibrillator. Regular device check-up was documented in all patients, presenting an ongoing high-degree AV-block. Neither device complications nor life-threatening tachyarrhythmias were documented after acute TTS event. However, patients comprising the device group suffered significantly more often from a highly reduced EF (30 ± 7.7% versus 39.1 ± 9.7%; p < 0.05), cardiogenic shock with use of inotropic agents (66.6% versus 16.6%; p < 0.05) and cardiopulmonary resuscitation (44.4% versus 5.3%; p < 0.05). Our data confirm the usefulness of pacemaker in TTS patients. However, the cardioverter defibrillator including wearable cardioverter defibrillator may not be recommended.
Key Teaching Points
• Wearables such as smartwatches can monitor beyond heart rate and heart rhythm.
• Specific smartwatches provide reliable measurements of electrocardiographic intervals (eg, QT interval).
• Correct analysis and interpretation of the QT interval in an individual with previously unknown long QT syndrome facilitated the diagnosis.