Accurate and precise plasma clearance measurement using four 99mTc-DTPA plasma samples over 4 h

• Published in: Nuclear medicine communications Vol. 37; no. 1; pp. 79 - 86
• Main Authors: Wanasundara, Surajith N, Wesolowski, Michal J, Barnfield, Mark C, Waller, Michael L, Murray, Anthony W, Burniston, Maria T, Babyn, Paul S, Wesolowski, Carl A
• Format: Journal Article
• Language: English
• Published: England Copyright Wolters Kluwer Health, Inc. All rights reserved 01-01-2016; Lippincott Williams & Wilkins
• Subjects: Adolescent; Adult; Child; Child, Preschool; Female; Glomerular Filtration Rate; Humans; Infant; Male; Metabolic Clearance Rate; Middle Aged; Original; Retrospective Studies; Technetium Tc 99m Pentetate - blood; Technetium Tc 99m Pentetate - pharmacokinetics; Time Factors; Young Adult
• ISSN: 0143-3636; 1473-5628
• DOI: 10.1097/MNM.0000000000000405

OBJECTIVESGlomerular filtration rate can be measured as the plasma clearance (CL) of a glomerular filtration rate marker despite body fluid disturbances using numerous, prolonged time samples. We desire a simplified technique without compromised accuracy and precision.
MATERIALS AND METHODSWe compared CL values derived from two plasma concentration curve area methods – (a) biexponential fitting [CL (E2)] and (b) Tikhonov adaptively regularized gamma variate fitting [CL (Tk-GV)] – for 4 versus 8 h time samplings from 412 Tc-DTPA studies in 142 patients, mostly paediatric patients, with suspected fluid disturbances.
RESULTSCL (Tk-GV) from four samples/4 h and from nine samples/8 h, both accurately and precisely agreed with the standard, which was taken to be nine samples/8 h CL from (noncompartmental) numerical integration [CL (NI)]. The E2 method, four samples/4 h, and nine samples/8 h median CL values significantly overestimated the CL (NI) values by 4.9 and 3.8%, respectively.
CONCLUSIONCompared with the standard, CL (E2) from four samples/4 h and from nine samples/8 h proved to be the most inaccurate and imprecise method examined, and can be replaced by better methods for calculating CL. The CL (Tk-GV) can be used to reduce sampling time in half from 8 to 4 h and from nine to four samples for a precise and accurate, yet more easily tolerated and simplified test.