Three‐dimensional canine renovascular structure and circulation visualized in situ with the dynamic spatial reconstructor

Abstract

The dynamic spatial reconstructor--a unique, high speed, volume-scanning, X-ray computed tomographic imaging system--was utilized to examine canine renovascular anatomy and renal circulation in situ. In each of the four kidneys examined in this study initial scans were done during bolus injections of angiographic contrast material into the renal artery. A subsequent scan was then performed following an injection of methyl-methacrylate-based casting compound that had been contrast enhanced with ethiodol. After the scans, each kidney was removed, and its parenchyma was digested in potassium hydroxide to expose the vascular cast. Comparison of casts with their reconstructed images and with images obtained during injection of contrast material showed that interlobar arteries and occasionally arcuate arteries could be clearly detected. Although discrete vessels less than 1 mm in diameter could not be resolved, dynamic changes in parenchymal distribution of density during passage of contrast material allowed interpretation of flow through the multiple capillary beds of the kidney. Such analysis indicated that maximal density was in the outer-middle zone of the cortex throughout the duration of the scan. Analysis of artery-to-vein transit time showed arrival of contrast material in the renal vein as soon as 3 sec, and continuation for longer than 8 sec, after the renal artery bolus. In conclusion, renal circulation in the dog can be discretely visualized with the dynamic spatial reconstructor up to the level of the arcuate arteries; however, capillary flow as a whole can be followed through the cortex, and the results suggest the presence of both rapid and slow components of peritubular circulation.

Vascular exchange in the kidney. Regional characterization by multiple indicator tomography.

“…Tomographic imaging of the indicator dilution process is well suited to regional studies of kidney function8 but has thus far been applied with single indicators to estimate regional blood flow and glomerular filtration rate. [18][19][20][21][22][23][24][25] Multiple indicator dilution (MID) is a method designed originally for whole-organ studies of vascular exchange.2,26,27 To our knowledge, it has not previously been applied to regional functional analysis. MID presents two or more tracers to a target organ, usually by means of a sharp bolus input to the organ's arterial inflow.…”