A study of technetium-99m red blood cell labeling efficiency in normal subjects for LVEF at King Chulalongkorn Memorial Hospital

Abstract

Introduction: There are many factors that diminishing the labeling of Tc-99m with Red Blood Cell. It sometimes occurred in nuclear medicine examination, and needed more acquisition time or repeating the examination in worst case. Objective: The purpose of this study is to compare labeling efficiency with image evaluation for labeling yield by nuclear medicine physician and to find the incident of poor labeling in normal subjects. Materials and methods: Patients with request for pre-chemotherapy Left Ventricular Ejection Fraction (LVEF) as baseline study and volunteers who did not on drug affecting red blood cell (RBC) labeling were included in this study. We measured labeling efficiency (LE), and performed anterior chest static image using Siemens SPECT camera model ECAM with Low Energy High Resolution(LEHR) collimator, matrix size 256x256, duration 2 minutes then submitted this image to nuclear medicine physician to evaluate the image as poor, moderate or good labeling. Results: There were 70 cases, 3 cases had LE < 10% with poor image evaluation, 3 cases had LE between 10-30% with moderate image evaluation and 64 cases had LE > 50% with good image evaluation. Conclusion: Repeated examination was needed if LE was less than 10% because of the poor image quality. If LE was between 10-30%, the technologist should increase the acquisition time 2-3 times more than usual. The image quality should met nuclear medicine physician satisfaction before discharging the patient.