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Estimating Differential Renal Function Using Ellipsoid Approximation of Renal Function on Computed Tomography
CUA Online Library. Nguyen L. 06/25/13; 31313; MP-06.12
Dr. Laura Nguyen
Dr. Laura Nguyen
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Abstract
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ESTIMATING DIFFERENTIAL RENAL FUNCTION USING ELLIPSOID APPROXIMATION OF RENAL VOLUME ON CT SCAN

Laura Nguyen, Fadi Kamal, Brian Blew

BACKGROUND: Living renal donors must undergo extensive medical investigations in order to be approved for the donor program. Among other testing, this includes both computed tomography (CT) scans to evaluate vascular anatomy and nuclear medicine renal scans to assess for differential renal function.

Extensive research has been done using complex models to calculate precise radiographic measurement of renal volume on CT in order to estimate differential renal function based on differential renal volumes. Thus, the necessity of the nuclear medicine renal scan can be eliminated, reducing the radiographic burden and time commitment of the potential donor and addressing the ongoing scarcity of the necessary radionucleotide. However, these models are rarely used as they are often cost-prohibitive due to the need for proprietary software and they are labor-intensive for radiologists.

METHODS: In this study, we examined whether a simplified estimation of differential renal volumes based on the ellipsoid formula (renal volume = πldw/6, where l, d, and w represent three dimensions of the kidney) using CT scans, may also adequately estimate differential renal function.

RESULTS: Charts of 79 consecutive living renal donors were reviewed retrospectively. The differential renal volumes measured on CT scans were reliable between operators (p<0.05). We found that the volume-based estimations of differential renal volume were in fact correlated to differential renal function on nuclear medicine scans (r=0.29, p<0.01). We were able to identify the kidney with the greater function in 53 (67%) of the 79 cases, and in all 8 (100%) of 8 cases in which the difference in differential renal function was clinically significant (>10% difference between kidneys).

CONCLUSIONS: These findings support removal of the nuclear medicine scan from routine assessment of potential kidney donors without the need for expensive radiologic software, but further research looking specifically at potential donors with clinically significant differential renal function between kidneys is required to confirm our findings.
ESTIMATING DIFFERENTIAL RENAL FUNCTION USING ELLIPSOID APPROXIMATION OF RENAL VOLUME ON CT SCAN

Laura Nguyen, Fadi Kamal, Brian Blew

BACKGROUND: Living renal donors must undergo extensive medical investigations in order to be approved for the donor program. Among other testing, this includes both computed tomography (CT) scans to evaluate vascular anatomy and nuclear medicine renal scans to assess for differential renal function.

Extensive research has been done using complex models to calculate precise radiographic measurement of renal volume on CT in order to estimate differential renal function based on differential renal volumes. Thus, the necessity of the nuclear medicine renal scan can be eliminated, reducing the radiographic burden and time commitment of the potential donor and addressing the ongoing scarcity of the necessary radionucleotide. However, these models are rarely used as they are often cost-prohibitive due to the need for proprietary software and they are labor-intensive for radiologists.

METHODS: In this study, we examined whether a simplified estimation of differential renal volumes based on the ellipsoid formula (renal volume = πldw/6, where l, d, and w represent three dimensions of the kidney) using CT scans, may also adequately estimate differential renal function.

RESULTS: Charts of 79 consecutive living renal donors were reviewed retrospectively. The differential renal volumes measured on CT scans were reliable between operators (p<0.05). We found that the volume-based estimations of differential renal volume were in fact correlated to differential renal function on nuclear medicine scans (r=0.29, p<0.01). We were able to identify the kidney with the greater function in 53 (67%) of the 79 cases, and in all 8 (100%) of 8 cases in which the difference in differential renal function was clinically significant (>10% difference between kidneys).

CONCLUSIONS: These findings support removal of the nuclear medicine scan from routine assessment of potential kidney donors without the need for expensive radiologic software, but further research looking specifically at potential donors with clinically significant differential renal function between kidneys is required to confirm our findings.
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