Evaluation of the utility of quantitative assessment using standardized uptake value in myocardial ¹²³ I-MIBG scintigraphy: a phantom study on the influence of lung and liver uptake

In this study, we aimed to clarify the utility of the myocardial standardized uptake value (SUV) method in myocardial¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy by evaluating the impact of lung and liver uptake changes on both the heart-to-mediastinum (H/M) and myocardial SUV. The Monte Carlo simulation code simulating medical imaging nuclear detectors was used to simulate the imaging of a myocardial phantom HL under the assumption of normal uptake in myocardial MIBG scintigraphy. In addition, imaging of multiple myocardial phantom HLs with different lung and liver uptake concentrations was simulated. Quantitative values for the myocardial SUV and H/M ratio were calculated from the simulated data of the digital myocardial phantom HL. The effects of lung and liver uptake variation were evaluated by assessing the relative standard deviation (RSD) of each calculated value. For lung uptake variations, the RSD of the myocardial SUV method was 1.34% for the maximum count and 1.64% for the mean count, whereas the RSD of the H/M ratio was 4.73%. For variations in liver uptake, the RSD of the myocardial SUV method was 1.73% for the maximum count and 0.72% for the mean count, with the RSD of the H/M ratio being 0.02%. After removing the segments clearly influenced by liver uptake, the RSD of the myocardial SUV method was 0.007% for the maximum value and 0.004% for the mean value, which were both smaller than the RSD of the H/M ratio. These findings indicate that the myocardial SUV method allows for a quantitative evaluation that is less influenced by lung and liver uptake compared with the H/M ratio, thereby enabling a more stable assessment of myocardial uptake.