Chronic renal failure (CRF) is associated with a 10 to 20-fold increase in cardiovascular risk. Vascular calcification (VC) is a prominent feature of cardiovascular disease in dialysis patients, and contributes to the excess mortality in this population. Adenine-induced CRF proved a suitable model to study uremia-related VC. This study explores micro-CT (m-CT) scanning as a tool to detect and follow-up VC in living uremic rats.

Thoracal m-CT scans (Skyscan 1076, Belgium) were performed in living rats under pentobarbital-anesthesia after 7 to 10 weeks of adenine-induced CRF. Scans (with 25 mm Ti-filter) were isotropic, with a voxel size of 35 × 35 × 35 mm. Virtual cross sections were reconstructed by Feldkamp cone-beam algorithm. Tissue calcium content was measured by atomic absorption spectroscopy and VC was scored histologically on Von Kossa stained sections.

In a feasibility study seven rats (a subset of a larger study) were scanned. In two animals, the calcified aortic wall was densely delineated on m-CT images, in agreement with highly increased bulk calcium content and histological Von Kossa positivity. The other animals did not show any signs of VC by any method. In a second study rats were screened after 7 weeks of CRF. Calcification was detected in 8/14 animals, 6 of which were rescanned one week later. A short in vivo scan was performed twice and demonstrated good reproducibility of the technique. Additionally, good correlation was found between in vivo scans and ex vivo scans of the animal and the paraffin-embedded aortas.

In conclusion, in vivo micro-CT scanning is a sensitive method to detect calcifications in the thoracic aorta of CRF rats. In the future, this promising technique will allow to follow-up and quantify the development, and potential reversal during treatment, of vascular calcifications in living animals.