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

Abstract

In previous work with the method of multiple indicator dilution (MID), we have established that a spatially distributed model of transcapillary exchange proposed by Goresky, Ziegler, and Bach (GZB) accurately describes, at the in vivo whole-organ level, the handling of extracellular indicators in the canine renal cortex. To date, however, it has not been possible to assess the key hypothesis that GZB corresponds to the actual local mechanism of exchange in vivo and is not just a compact summary of the kidney's average whole-organ behavior. By adapting the MID method to high speed computed tomography (CT), we are now able to report that the GZB mechanism is an accurate description of renal cortical transcapillary exchange down to volumes of cortical tissue comprising no more than a few per cent of the total cortical mass, i.e., containing no more than a few thousand nephrons. A small bolus of iohexol (radiopaque extracellular indicator) or iodipamide ethyl ester microparticles (radiopaque plasma indicator) injected into the renal artery was followed by CT as it passed through the kidney and into the renal vein. Time-attenuation value curves of the two contrast media obtained from the renal vein and from regions of interest in the cortex were then modeled with the GZB mechanism and with a more complex formulation that includes GZB as a limiting case. When applied to the data, the models converged to GZB as the best fit for each region examined. The GZB mechanism is found to provide excellent agreement with the regional data.

Dosing of indocyanine green for intraoperative laser fluorescence angiography in kidney transplantation

“…However, this allows a visualization of microperfusion at the most distant regions from the central vessels of the kidney. As a previous study by Lumsden et al shows cortical perfusion resembles the perfusion of inner zones of the kidney. Another limitation includes the retrospective design yielding differently sized dosage groups according to empirical observations.…”

Dynamic Three-dimensional MR Renography for the Measurement of Single Kidney Function: Initial Experience

“…One advantage of a relatively high spatial resolution 3D MR method over scintigraphy and other clearance measurements is the ability to assess also intrarenal regional function (12), which may be altered in diseases affecting segmental anatomy, such as fibromuscular dysplasia of the segmental renal arteries. Quantification of contrast material in multiple functional compartments, such as the cortex, medulla, and collecting system, may also be useful for a compartmental analysis of renal physiologic function (29).…”

Real-time visualization of renal microperfusion using laser speckle contrast imaging

“… 5 It is based on the misconception that total RBF adequately reflects RCM. 6 Therefore, the use of techniques that can detect heterogeneity of blood flow is preferred. 7 Postoperative duplex sonography has the ability to detect local perfusion deficits 8 and has been validated in several studies.…”