Correction of iodine-123-labeled meta-iodobenzylguanidine uptake with multi-window methods for standardization of the heart-to-mediastinum ratio

Background. To overcome differences in the choice of collimator for an iodine-123 (I-123)-labeled meta-iodobenzylguanidine ((MIBG) heart-to-mediastinum (H/M) ratio, we examined multi-window correction methods with I-123 dual-window (IDW) and triple-energy window (TEW) acquisition. Methods and Results. Standard phantoms, which consisted of the heart, mediastinum, lung, and liver, were generated. Three correction methods were compared: TEW and two IDW methods (IDW0 and IDW1). Low-energy high-resolution (LEHR), medium-energy (ME), and I-123-specific low-medium-energy high-resolution (LMEHR) collimators were used. Clinical studies were performed in 10 patients. In the phantom study, the HIM ratio was significantly underestimated without correction, with both the LEHR and ME collimators (70% and 88% of the true value). When H/M with the LEHR collimator was divided by uncorrected HIM with the ME collimator, the ratio (mean = SD) was 80% +/- 5%, 98% +/- 5%, 104% +/- 7%, and 98% +/- 5% for the no-correction, TEW, IDW0, and IDW, methods, respectively. Clinical studies with the LEHR collimator after TEW and IDW correction (uncorrected average HIM ratio, 1.86 +/- 0.23; TEW, 2.47 +/- 0.46, P =.0015; IDW, 2.46 +/- 0.46, P =.0017) provided comparable values to the uncorrected ME collimator (2.56 +/- 0.46, P = NS vs TEW and IDW). Conclusions. The H/M ratio with the ME collimator, after application of the TEW or IDW methods, was close to the theoretical value in the phantom study. However, the corrected HIM ratios with the LEHR collimator provided comparable H/M ratios to the uncorrected ME data in phantom and clinical studies. (J Nucl Cardiol 2007;14:843-51).