Purpose: Although13 N-Ammonia (NH3) positron emission tomography (PET) has been increasingly applied in clinical practice, its long examination time remains a limitation, primarily due to the required interval for sufficient radioactive decay.This study aimed to validate a low-dose rest scan to reduce the required interval and shorten the overall examination time.Methods: This prospective study enrolled 24 patients (age 6512, 15 male) with known or suspected coronary artery disease.To validate the low-dose approach, each patient underwent two separate rest scans consecutively: a low-dose scan (approximately one-third the standard dose) and a standard-dose scan (555 to 740 MBq), immediately followed by standard pharmacological stress scan.PET parameters, including end-diastolic/systolic volumes (EDV/ESV, mL), ejection fraction (EF, %), summed rest score (SRS), and rest myocardial blood flow (MBF, mL/g/min), were compared between the two rest protocols.Results: EF, EDV, ESV, SRS, and MBF showed significant correlation between low and standard-dose (r=0.99,0. 99, 0.99, 0.99, and 0.93 for EF, EDV, ESV, SRS, and MBF; p<0.0001 for all).Bland-Altman plot showed a good agreement (bias 0.303.64,-0.301.89,-0.472.04,-0.210.78,and 0.0330.096;limits of agreement -4.86 to 5.47, -4.02 to 3.41, -3.52 to 4.48, -1.7 to 1.3, and -0.22 to 0.15 for EF, EDV, ESV, SRS, and MBF).Conclusion: A low-dose NH3 rest PET protocol is feasible and provides quantitative results highly comparable to the standard-dose.Implementing this approach can shorten examination times and improve clinical throughput.
Kaimoto et al. (Thu,) studied this question.