Weight-based Determination of Administered Activity in Tc-DMSA Renal SPECT in Infants: Are Minimum Administered Activities Necessary?

Overview

Journal Pediatr Radiol

Specialty Pediatrics

Date 2025 Feb 11

PMID 39934452

Authors

Neha Kwatra

P Hendrik Pretorius

S Ted Treves

Reza Vali

Valentina Ferrer Valencia

Weibin Fu

Xinhua Cao

Yongyi Yang

Michael King

Frederic H Fahey

Affiliations

Soon will be listed here.

Abstract

Background: The North American consensus guidelines recommend a weight-based administered activity for renal cortical scintigraphy with Tc-dimercaptosuccinic acid (DMSA; 1.85 MBq/kg or 0.05 mCi/kg). Patients weighing less than 10 kg are recommended to receive a minimum administered activity of 18.5 MBq (0.5 mCi), irrespective of their weight. This approach is presumably to provide sufficient counts for adequate image quality, but it has not been rigorously evaluated.

Objective: To compare the adequacy of image quality of infant DMSA renal SPECT examinations obtained using the minimum administered activity recommended by the consensus guidelines with simulated data utilizing a strict weight-based dosage.

Materials And Methods: Phase 1: Datasets of 55 infants (29 females, 26 males, median age 3.0 months and weight 5.6 kg) undergoing DMSA SPECT from 2016 to 2021 were identified with 7 used for training and 48 used for study analysis. Data from patients receiving the administered activity recommended by the consensus guidelines ("full dosage", group A) were processed using binomial resampling to add Poisson noise to mimic a strict weight-based scheme ("simulated reduced dosage", group A'). Three experienced nuclear medicine physicians, who were blinded to group membership and clinical information, independently evaluated adequacy of image quality for clinical interpretation on a 4-point scale. Student's paired t-test was utilized for group comparisons and inter-rater agreements were calculated using kappa statistics. Phase 2: Group A' simulated data were compared to a second cohort of Tc-DMSA SPECT cases where the administered activity followed a strict weight-based regime ("true reduced dosage", group B). Subjects weighing between 4-7 kg were selected (group A', 10 patients, 4 females, 6 males, median age 3.00 months and weight 5.35 kg) to compare with similar-weight group B subjects (10 patients, 5 females, 5 males, median age 2.50 months and weight 6.05 kg). The same observers and 4-point scale from phase 1 were used. The Wilcoxon rank sum test was utilized for analysis.

Results: Observers' ratings were combined for analysis resulting in n=144 case-pairs (3 observers × 48 case-pairs) in phase 1. In phase 1, the ratings of groups A and A' were identical for 73.6% (106/144) of case-pairs and never differed by more than ±1 level. No significant rating difference was found between the groups (mean (SD) of 1.17 (0.93) versus 1.22 (0.98), P=0.20). Similarly, in phase 2, no significant rating difference was found between groups A' and B (mean (SD) of 0.80 (0.81) versus 0.50 (0.68), P=0.14).

Conclusion: There was no significant difference in the adequacy of image quality of Tc-DMSA SPECT examinations using a strict weight-based dosage compared to using the recommended minimum dosage for infants as small as 3 kg.

References

Li Y, OReilly S, Plyku D, Treves S, Du Y, Fahey F . A projection image database to investigate factors affecting image quality in weight-based dosing: application to pediatric renal SPECT. Phys Med Biol. 2018; 63(14):145004. PMC: 6105284. DOI: 10.1088/1361-6560/aacbf0. View

OReilly S, Plyku D, Sgouros G, Fahey F, Treves S, Frey E . A risk index for pediatric patients undergoing diagnostic imaging with (99m)Tc-dimercaptosuccinic acid that accounts for body habitus. Phys Med Biol. 2016; 61(6):2319-32. PMC: 5736793. DOI: 10.1088/0031-9155/61/6/2319. View

Brown J, Sexton-Stallone B, Li Y, Frey E, Treves S, Fahey F . Body morphometry appropriate computational phantoms for dose and risk optimization in pediatric renal imaging with Tc-99m DMSA and Tc-99m MAG3. Phys Med Biol. 2020; 65(23):235026. DOI: 10.1088/1361-6560/abb1da. View

Juan Ramon A, Yang Y, Pretorius P, Slomka P, Johnson K, King M . Investigation of dose reduction in cardiac perfusion SPECT via optimization and choice of the image reconstruction strategy. J Nucl Cardiol. 2017; 25(6):2117-2128. PMC: 9407649. DOI: 10.1007/s12350-017-0920-1. View

Gelfand M, Parisi M, Treves S . Pediatric radiopharmaceutical administered doses: 2010 North American consensus guidelines. J Nucl Med. 2011; 52(2):318-22. DOI: 10.2967/jnumed.110.084327. View

Fahey F, Zukotynski K, Zurakowski D, Markelewicz R, Falone A, Vitello M . Beyond current guidelines: reduction in minimum administered radiopharmaceutical activity with preserved diagnostic image quality in pediatric hepatobiliary scintigraphy. Eur J Nucl Med Mol Imaging. 2014; 41(12):2346-53. DOI: 10.1007/s00259-014-2860-1. View

Bolch W, Eckerman K, Sgouros G, Thomas S . MIRD pamphlet No. 21: a generalized schema for radiopharmaceutical dosimetry--standardization of nomenclature. J Nucl Med. 2009; 50(3):477-84. DOI: 10.2967/jnumed.108.056036. View

Gelfand M . Dose reduction in pediatric hybrid and planar imaging. Q J Nucl Med Mol Imaging. 2010; 54(4):379-88. View

Bai Y, Wang D . Select the optimized effective dose to reduce nuclear radiations in pediatric nuclear medicine. World J Nucl Med. 2014; 13(1):40-5. PMC: 4149768. DOI: 10.4103/1450-1147.138573. View

10.

Li Y, OReilly S, Plyku D, Treves S, Fahey F, Du Y . Current pediatric administered activity guidelines for Tc-DMSA SPECT based on patient weight do not provide the same task-based image quality. Med Phys. 2019; 46(11):4847-4856. PMC: 7080403. DOI: 10.1002/mp.13787. View

11.

Li Y, Brown J, Xu J, Chen J, Ghaly M, Dugan M . Girth-based administered activity for pediatric Tc-DMSA SPECT. Med Phys. 2023; 51(2):1019-1033. PMC: 10799972. DOI: 10.1002/mp.16602. View

12.

Ichikawa S, Sugimori H, Ichijiri K, Yoshimura T, Nagaki A . Acquisition time reduction in pediatric Tc-DMSA planar imaging using deep learning. J Appl Clin Med Phys. 2023; 24(6):e13978. PMC: 10243333. DOI: 10.1002/acm2.13978. View

13.

Lin C, Chang Y, Chiu H, Cheng C, Huang H . Differentiation between normal and abnormal kidneys using Tc-DMSA SPECT with deep learning in paediatric patients. Clin Radiol. 2023; 78(8):584-589. DOI: 10.1016/j.crad.2023.04.015. View

14.

Poli G, Coca M, Torres L, Fahey F, Lassmann M, Chapple C . Developing and Implementing an Imaging Optimization Study in Pediatric Nuclear Medicine: Experience and Recommendations from an IAEA-Coordinated Research Project. J Nucl Med. 2020; 62(4):570-576. DOI: 10.2967/jnumed.120.244616. View