I-123 MIBG cardiac uptake measurements: limitations of collimator choice and scatter correction in the clinical context

Fletcher, A. M., Motherwell, D. W., Small, A. D., McCurrach, G. M., Goodfield, N. E.R., Petrie, M. C. , Martin, W. and Cobbe, S. M. (2010) I-123 MIBG cardiac uptake measurements: limitations of collimator choice and scatter correction in the clinical context. Nuclear Medicine Communications, 31(7), pp. 629-636. (doi:10.1097/MNM.0b013e3283375639) (PMID:20224458)

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Abstract

OBJECTIVE: Low uptake of metaiodobenzylguanidine (MIBG) in patients with heart failure generally indicates poor prognosis. Our objective was to determine the best method for calculating I-123 MIBG uptake. MIBG uptake as a percentage of the injected dose is presented as an alternative method for serial assessment. METHODS: Patients with chronic heart failure were imaged with I-123 MIBG with both a medium-energy (ME) collimator and a low-energy high-sensitivity (LEHS) collimator. Scatter correction was used to correct the LEHS images. Heart-to-mediastinal (H/M) ratio and the percentage of myocardial uptake of MIBG were obtained. RESULTS: Mean H/M ratios for the ME images, LEHS images and scatter-corrected LEHS images were 2.45+/-0.61, 2.22+/-0.47 and 2.51+/-0.62, respectively. Mean H/M ratio was significantly different among all the three sets (P<0.001) of images. The average difference in H/M ratios between the ME images and LEHS images was lower when scatter correction was applied (4.95% vs. 9.79%). The error in calculating the myocardial uptake as a percentage of the injected dose was significantly lower than the error in calculating H/M ratio (0.2 vs.10.2% LEHS; 0.3 vs.16.0% ME; 0.2 vs.11.8% LEHS scatter corrected). CONCLUSION: For quantitative assessment of H/M ratio in I-123 MIBG imaging a LEHS collimator can be used in place of a ME collimator to achieve better counting statistics, but scatter correction must be used. The calculation of the myocardial uptake as a percentage of the injected dose has potential as an alternative method of measurement, particularly for serial assessment.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Martin, Professor William and Petrie, Professor Mark and Cobbe, Professor Stuart
Authors: Fletcher, A. M., Motherwell, D. W., Small, A. D., McCurrach, G. M., Goodfield, N. E.R., Petrie, M. C., Martin, W., and Cobbe, S. M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Nuclear Medicine Communications
Publisher:Lippincott, Williams and Wilkins
ISSN:0143-3636
ISSN (Online):1473-5628

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