In patients with PXE, etidronate reduced arterial calcification and subretinal neovascularization events but did not lower femoral fluoride sodium positron emission tomography activity compared with placebo, without important safety issues. (Treatment of Ectopic Mineralization in Pseudoxanthoma elasticum; NTR5180).

Dose escalation above 60 Gy for locally advanced rectal cancer results in high pCR-rates and acceptable early toxicity. This observation needs to be further investigated within larger randomized controlled phase 3 trials in the future.

Objectives To investigate the accuracy of bone mineral density (BMD) quantification using dual-layer spectral detector CT (SDCT) at various scan protocols. Methods Two validated anthropomorphic phantoms containing inserts of 50-200 mg/cm 3 calcium hydroxyapatite (HA) were scanned using a 64-slice SDCT scanner at various acquisition protocols (120 and 140 kVp, and 50, 100 and 200 mAs). Regions of interest (ROIs) were placed in each insert and mean attenuation profiles at monochromatic energy levels (90-200 keV) were constructed. These profiles were fitted to attenuation profiles of pure HA and water to calculate HA concentrations. For comparison, one phantom was scanned using dual energy X-ray absorptiometry (DXA). Results At both 120 and 140 kVp, excellent correlations (R = 0.97, P < 0.001) were found between true and measured HA concentrations. Mean error for all measurements at 120 kVp was -5.6 ± 5.7 mg/cm 3 (-3.6 ± 3.2%) and at 140 kVp -2.4 ± 3.7 mg/cm 3 (-0.8 ± 2.8%). Mean measurement errors were smaller than 6% for all acquisition protocols. Strong linear correlations (R 2 ≥ 0.970, P < 0.001) with DXA were found.Conclusions SDCT allows for accurate BMD quantification and potentially opens up the possibility for osteoporosis evaluation and opportunistic screening in patients undergoing SDCT for other clinical indications. However, patient studies are needed to extend and translate our findings. Key points• Dual-layer spectral detector CT allows for accurate bone mineral density quantification.• BMD measurements on SDCT are strongly linearly correlated to DXA.• SDCT, acquired for several indications, may allow for evaluation of osteoporosis.• This potentially opens up the possibility for opportunistic osteoporosis screening.

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