Correction of collimator-dependent differences in the heart-to-mediastinum ratio in 123I-metaiodobenzylguanidine cardiac sympathetic imaging: Determination of conversion equations using point-source imaging

• Published in: Journal of nuclear cardiology Vol. 24; no. 5; pp. 1725 - 1736
• Main Authors: Inoue, Yusuke, Abe, Yutaka, Kikuchi, Kei, Matsunaga, Keiji, Masuda, Ray, Nishiyama, Kazutoshi
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 01.10.2017; Springer US
• Subjects: 123I-metaiodobenzylguanidine (MIBG); Cardiology; collimator; heart-to-mediastinum (H/M) ratio; Imaging; Medicine; Medicine & Public Health; Nuclear Medicine; Original; Original Article; Radiology; septal penetration; LEHR; SLEHR; LME; H/M; 123I-metaiodobenzylguanidine (MIBG); collimator; LEAP; CHR; heart-to-mediastinum (H/M) ratio; ROI; septal penetration; 123I-MIBG; ME; LE; IDW; I-metaiodobenzylguanidine (MIBG)
• ISSN: 1071-3581; 1532-6551
• DOI: 10.1007/s12350-016-0546-8

Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in 123I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences. Four hours after 123I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators before and after 123I-dual-window penetration correction were compared with the ME-derived standard values to determine patient-based conversion equations for empiric and combined corrections, respectively. A 123I point source was imaged with various collimators, and the central ratio, the ratio of count in a small central region of interest to count in a large one, was calculated. The method of predicting the conversion equations from the central ratios was determined. Correction using the patient-based conversion equations removed systematic underestimation of the H/M ratios obtained with the non-ME collimators, and combined correction depressed residual random errors to some degree. Point-source-based equations yielded results comparable to the patient-based equations. Empiric and combined corrections effectively reduce collimator-dependent differences in the H/M ratio. The conversion equations can be predicted from simple point-source imaging, which would allow to apply these corrections to data obtained with various collimators.