The ability to determine the percentage of kidney contribution to excretory function. Preliminary results

Purpose. Determination of the possibility of using kidney segmentation to obtain data on their volume and density characteristics to assess the split renal function.

Material and methods. The data of 31 patients who underwent nephroscintigraphy and CT examination of the kidneys with contrast were analyzed. Segmentation of both kidneys into the nephrographic phase of contrast was performed at the workstation using the Vitrea Advanced Visualization program. The obtained values of the volume were multiplied at the attenuation coefficient of X-ray radiation in Hounsfield units (HU) for each kidney to obtain the "mass" of the contrast preparation. Having divided the obtained value of each kidney by their sum value and multiplying by 100%, we obtained a split contribution of each kidney to their total excretory function in percentages. To verify the need to introduce parenchymal density into calculations in the native phase of the study, the density of the parenchyma of both kidneys was measured at three levels in the native phase, then, the calculated arithmetic mean was subtracted from the average density of the renal parenchyma in the nephrographic phase. Subsequently, the same calculations were performed to obtain the percentage contribution of the kidneys as before deducting the native density. Nephroscintigraphy was performed in various medical institutions. Studies were conducted with technetium compounds (99mTc). For further analysis, data on the percentage contribution of each kidney to their overall excretory function were taken.

Results. The obtained data on the percentage contribution of the kidneys to their total excretory function obtained by nephroscintigraphy were compared with the calculated CT data. The analysis showed a very high correlation and covariance of these results (the correlation coefficient is 0.99 (p < 0.001), the covariance coefficient is 0.95 (p < 0.001)). When conducting a correlation analysis of the results of nephroscintigraphy with CT data, where an additional correction was made for the native density of parenchyma (it was subtracted from the average density of parenchyma in the nephrographic phase), the results remained the same: the correlation coefficient was 0.99 (p < 0.001); the covariance coefficient was 0.95 (p < 0.001).

Conclusions. An accessible and practical method for evaluating split renal function has been developed. The method does not require the implementation of a clearly regulated time protocol for multiphase CT. CT data performed in any medical institution can be evaluated. The method does not require additional assessment of the native densitometric characteristics of the kidneys. The results obtained using the method showed a very high correlation with the data of dynamic nephroscintigraphy.

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