open access

Vol 5, No 2 (2002)
Published online: 2002-06-07
Submitted: 2012-01-23
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Optimal time window for measurement of renal output parameters

Jacob D. Kuyvenhoven, Hamphrey R. Ham, Amy Piepsz
Nucl. Med. Rev 2002;5(2):105-108.

open access

Vol 5, No 2 (2002)
Published online: 2002-06-07
Submitted: 2012-01-23

Abstract

Although normalised residual activity (NORA) and output efficiency (OE) are usually measured at a fixed time t, their dependency on t may affect the prediction of mean transit time (MTT). This study aimed to evaluate their degree of dependency on t and to determine an optimal time of measurement by assessment of their relationship with MTT for various times t. A simulation model generated 232 cortical renograms by convolving one plasma disappearance curve with 232 created cortical retention functions. The results show that considerable changes are observed for NORA and OE , depending on the time of measurement t. The choice of this time significantly influences the predictive value of these parameters for estimating MTT. The optimal time for measurement of NORA and OE should be close to the MTT, at the moment when emptying takes place. In the clinical practice, it should be adapted to the clinical problem under investigation.

Abstract

Although normalised residual activity (NORA) and output efficiency (OE) are usually measured at a fixed time t, their dependency on t may affect the prediction of mean transit time (MTT). This study aimed to evaluate their degree of dependency on t and to determine an optimal time of measurement by assessment of their relationship with MTT for various times t. A simulation model generated 232 cortical renograms by convolving one plasma disappearance curve with 232 created cortical retention functions. The results show that considerable changes are observed for NORA and OE , depending on the time of measurement t. The choice of this time significantly influences the predictive value of these parameters for estimating MTT. The optimal time for measurement of NORA and OE should be close to the MTT, at the moment when emptying takes place. In the clinical practice, it should be adapted to the clinical problem under investigation.
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Keywords

renography; output efficiency; NORA; simulation study

About this article
Title

Optimal time window for measurement of renal output parameters

Journal

Nuclear Medicine Review

Issue

Vol 5, No 2 (2002)

Pages

105-108

Published online

2002-06-07

Bibliographic record

Nucl. Med. Rev 2002;5(2):105-108.

Keywords

renography
output efficiency
NORA
simulation study

Authors

Jacob D. Kuyvenhoven
Hamphrey R. Ham
Amy Piepsz

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