Integrated backscatter for the in vivo quantification of supraphysiological vitamin D(3)-induced cardiovascular...

Cardiovascular calcifications are frequently found in the aging population and are independent predictors of future cardiovascular events. Integrated backscatter (IB) of ultrasound reflectivity can easily quantify calcifications. For this purpose, 30 male Wistar rats received 25,000 IU/kg/day of vitamin D(3) (group 1, n = 8), 18,800 IU/kg/day (group 2, n = 8), or injections with the vehicle only (group 3, n = 14), for 10 weeks. Echocardiographic calibrated IB (cIB) was measured and calculated at baseline and after 10 weeks, followed by ex vivo micro-CT and histopathology of the aortic valve, ascending aorta, and myocardium. After 10 weeks, the mean cIB value of the aortic valve was significantly higher for vitamin D(3)-dosed animals compared to controls. The mean cIB value of the ascending aorta and the myocardium was also significantly higher in group 1 compared to group 3. In vivo IB results were confirmed by ex vivo micro-CT and histopathology. In conclusion, IB is a non-ionizing, feasible, and reproducible tool to quantify cardiovascular calcifications in an in vivo rat model. The integration of IB in the standard echocardiographic examination for the quantification of cardiovascular calcifications could be useful for serial evaluation of treatment efficacy and for prognosis assessment.