Imciromab (monoclonal antimyosin antibody Fab) pentetate is a murine monoclonal antibody Fab (fragment antigen binding) derivative. It is specific for the human cardiac myosin heavy chain and localises to areas of cardiac myocyte necrosis. Indium In-111 imciromab pentetate imaging is a well tolerated, non-invasive method of assessing the presence and severity of cardiac allograft rejection. It has also been successfully used to confirm the presence and size of acute myocardial infarction (AMI), the presence of myocarditis and for the early detection of anthracycline cardiotoxicity. However, the 24- to 48-hour delay between administration and imaging restricts its use in conditions where the rapid diagnosis of cardiac disorders is essential, and the decay half-life of indium In-111 (67 hours) limits the dose of radiolabel to approximately 2 mCi. Nevertheless, except in patients requiring an immediate diagnosis of AMI, indium In-111 imciromab pentetate imaging provides significant diagnostic and prognostic information, aiding patient management and the selection of appropriate treatment, and, in some patients, abrogating the need for endomyocardial biopsy. Imciromab (monoclonal antimyosin antibody Fab) pentetate is a murine monoclonal antibody Fab (fragment antigen binding) fragment linked to a bifunctional chelating agent. It is specific for human cardiac myosin heavy chains and localises to areas of cardiac myocyte necrosis, where disruption of the cell membrane exposes cardiac myosin. Imciromab pentetate is chelated to indium In-111 prior to administration for radioimaging. Indium In-111 imciromab pentetate imaging facilitated assessment of infarct size and location in animal models of acute myocardial infarction (AMI). It indicated the location and severity of rejection in animal models of cardiac transplantation, and identified acute murine myocarditis. The elimination half-life in blood of indium In-111 imciromab pentetate in patients with AMI is about 5 hours. In mice, uptake of the radiolabel was concentrated in the kidneys (20 to 25% of the dose) and liver (5% of the dose) 24 hours after administration. Uptake in the heart was 6% in animals with acute myocarditis but only 1% in uninfected mice. In studies involving a total of more than 800 patients, indium In-111 imciromab pentetate imaging correctly identified AMI in patients with or without definitive clinical findings, with an overall sensitivity of 93%. It also provided an assessment of infarct size and, in dual isotope imaging with thallium Tl-201, identified patients at risk of developing further cardiac ischaemia. Indium In-111 imciromab pentetate imaging had a sensitivity of 80 to 100% in studies in patients with cardiac allograft rejection, with the ratio of cardiac to pulmonary uptake (HLR) providing an indication of rejection severity. In patients with suspected myocarditis a negative indium In-111 imciromab pentetate scan may abrogate the need for endomyocardial biopsy. A positive scan in patients with suspected myocarditis or acute-onset idiopathic dilated cardiomyopathy identifies those more likely to subsequently show clinical improvement. Preliminary data suggest indium In-111 imciromab pentetate imaging may also be useful in the early detection of anthracycline-associated cardiotoxicity. Indium In-111 imciromab pentetate has been very well tolerated in clinical trials, with few adverse events reported. Wheal and flare reactions to intradermal testing prior to intravenous administration are seen only rarely (2 reported cases in >330 patients). The development of human-antimurine antibodies is seldom noted and has not been associated with clinical sequelae. Eosinophilia, and hypotension and confusion have each been reported in 1 patient receiving indium In-111 imciromab pentetate but causality has not been established. Patients should receive intravenous indium In-111 imciromab pentetate 0.5mg (2 mCi). Imaging is usually performed 24 and/or 48 hours after administration. Planar imaging with a gamma camera is usually performed in 3 views, each over 10 minutes. Single photon emission computed tomography (SPECT) imaging comprises 64 frames over 180° at 30 seconds per frame.