Intrarenal artery delineation with ultra high resolution, flat panel based, volume computerized tomography: outer limits of spatial resolution.

Abstract

New methods of noninvasive high resolution imaging may improve the delineation of tumor microvessels and, thus, be of significant help in surgical planning and cost-effective monitoring of novel anti-angiogenic therapy. We determined the maximum delineation of intrarenal microvessels with a novel flat panel based volume computerized tomography system in an experimental setting. We prospectively evaluated 13 porcine renal specimens for intrarenal vessel delineation using a prototype gantry based, flat panel, cone beam computerized tomography system. The gantry incorporates an array of a 40 x 30 cm(2) CsI amorphous silicon flat panel detector consisting of a 2,048 x 1,536 matrix. After catheterizing the renal artery with a 5Fr end hole catheter a contrast enhanced scan was performed using BaS as contrast medium at a dilution of 200 mg/ml. The diameter of all definable arterial branches was determined using a software tool based on Medical Imaging and Interaction Toolkit, allowing semi-automatic segmentation of the vessel tree. In step 1 the vessel tree is segmented by a 3-dimensional region growing algorithm. Following its medial axis the vessel tree is extracted and converted to a representation, including the diameter of the vessels. In each kidney an average +/- SD of 47,454 +/- 22,382 arterial branches could be delineated. The diameter of the branches was 0.029 (mean 0.032 +/- 0.0025) to 3.444 mm (mean 1.813 +/- 0.6139) with a median of 0.263 mm. Of visible intrarenal arteries 2.7% had a vessel diameter of 0.029 mm. Flat panel based volume computerized tomography can visualize intrarenal microvessels down to a diameter of 0.03 mm. It may improve the assessment of renal microvessel architecture in healthy patients and in those with pathological conditions.