['Up to now, there has been limited investigation into cell therapy in the chronic phase of severe myocardial infarction (MI), and many questions remain concerning the contribution of the engrafted cells and especially their impact on the reperfusion of MI areas, when assessed by objective quantitative imaging techniques. This randomized pilot SPECT, PET, and MRI study was aimed at assessing the effects of bone marrow mononuclear cells (BMNCs) when implanted in areas of severe and chronic MI.', 'Fourteen patients, who were referred for coronary artery bypass grafting (CABG) and in whom a screening MIBI-SPECT revealed severely damaged myocardium (<50% uptake under nitrate), were randomized between a cell therapy group (n = 7; CABG and injection of BMNCs within MI areas) and a control group (n = 7; CABG alone).', 'The MI areas exhibited a posttherapeutic enhancement in the rest-uptake of MIBI in the cell therapy group [difference between 6-month control and baseline: +6.8% (5.4%), P = 0.03] but not in the control group [+1.0% (4.3%)]. However, in a per-patient analysis, this improvement was significant (> +9%) in only 3 cell therapy patients, whose MI areas before therapy had a higher FDG uptake [59% (9%) vs 38% (8%), P = 0.03] and a lower transmural extent at MRI [40% (6%) vs 73% (18%), P = 0.03] when compared with the other cell therapy patients.'] Is residual viability a predictor of the perfusion enhancement obtained with the cell therapy of chronic myocardial infarction : a pilot multimodal imaging study?