Computerized schemes take an important role in maintaining the reproducibility of results in quantitative analysis of 123I meta-iodobenzyl guanidine (123I MIBG) scintigraphy. The authors studied a computerized scheme for obtaining heart-to-mediastinum ratios from scintigram data. The computerized scheme is based on image registration between chest radiograms and scintigrams. The use of registered images enables location of myocardial and mediastinum regions in scintigram because these regions are easily recognized even in case of low myocardial MIBG uptake. The registered result is utilized to reduce the variation in determined shapes for myocardial regions by manual procedure. At the 2016 Japanese Society of Nuclear Cardiology Annual Scientific Meeting, the authors, by summarizing their fundamental techniques, reported the prototype computer software, examples of measurement results using the software, and future aspects of developing such computerized schemes by clinical application of their research. An overview of the scheme is provided in this review article.