Cardiac 123I-MIBG normal uptake values are population-specific: Results from a cohort of controls over 60 years of age

Purpose Cardiac I-123-MIBG image interpretation is affected by population differences and technical factors. We recruited older adults without cognitive decline and compared their cardiac MIBG uptake with results from the literature. Methods Phantom calibration confirmed that cardiac uptake results from Japan could be applied to our center. We recruited 31 controls, 17 individuals with dementia with Lewy bodies (DLB) and 15 with Alzheimer's disease (AD). Images were acquired 20 minutes and four hours after injection using Siemens cameras with medium-energy low-penetration (MELP) collimators. Local normal heart-to-mediastinum (HMR) ratios were compared to Japanese results. Results Siemens gamma cameras with MELP collimators should give HMRs very close to the calibrated values used in Japan. However, our cut-offs with controls were lower at 2.07 for early and 1.86 for delayed images. Applying our lower cut-off to the dementia patients may increase the specificity of cardiac MIBG imaging for DLB diagnosis in a UK population without reducing sensitivity. Conclusions Our local HMR cut-off values are lower than in Japan, higher than in a large US study but similar to those found in another UK center. UK centers using other cameras and collimators may need to use different cut-offs to apply our results.

Automated summary

This study suggests that interpretation of cardiac I-123-MIBG images in the UK may be influenced by population differences and technical factors, with potential implications for DLB diagnosis.