Development of a PET-MR Myocardial Perfusion Examination Using Regadenoson

Simultaneous acquisition PET-MRI is a new technology that has the potential to significantly impact diagnostic patient care. It combines high signal resolution MRI anatomic imaging and PET biological measurements, with the added benefit of radiation dose reduction in comparison to PET-CT. As the incidence of false positive SPECT-MPI studies secondary to attenuation artifact is relatively high and MRI coverage of the left ventricular myocardium is limited, it is likely that one of the immediate applications of PET-MRI technology is myocardial ischemia assessment.

PET has long been considered the noninvasive reference standard for myocardial perfusion. However, delayed contrast enhanced (DCE) MRI is very sensitive for infarct detection. Indeed, both PET and MR imaging have the potential to provide comprehensive whole heart ischemia and infarct detection.

PET-MR technology, with its ability to obtain simultaneous perfusion information via both PET and MRI, has the potential to obtain multiple, possibly redundant, data sets. On the other hand, it also has the potential to combine the best of both techniques to provide a highly robust examination that is both shorter and of lower radiation dose than the standard myocardial PET perfusion examination. Optimization of a protocol is necessary to develop a comprehensive protocol without redundancy. Because of its single injection capability, regadenoson is ideally suited to a protocol that will assess and employ dual-modality myocardial perfusion data collection.

It is expected that the best candidates for PET-MR myocardial perfusion imaging will likely be a) patients whose body habitus suggests that their SPECT-MPI examination would be limited by attenuation artifact -- women with large breasts and patients (usually men) with abdominal obesity and/or b) patients who may have a smaller region of ischemia that might be missed on an MRI examinations with limited perfusion coverage.

Inclusion criteria

• Patients who have had a clinically ordered rest/regadenoson single-isotope SPECT-MPI study within 10 days prior to cardiac PET-MRI examination
• Reversible perfusion abnormalities on SPECT imaging in at least 2 contiguous myocardial segments
• Patients for whom standard of care coronary ICA is planned

Exclusion criteria

• An clinical event (ie; worsening angina pectoris or myocardial infarction) occuring after the SPECT-MPI and before the cardiac MRI examination
• Myocardial revascularization occuring after the SPECT-MPI and before the cardiac MRI examination
• Contraindications to MR imaging (pacemaker, brain aneurysm clips, shrapnel, etc.)
• Renal insufficiency (GFR < 60 mL/min/1.73m2)
• Allergy or other contraindication to gadolinium-based MR contrast agent
• Second or third degree atrioventricular (AV) block
• Active asthma
• Seizures
• Current hypotension (<100/60)
• Current hypertension (>160/90)
• Pregnancy
• Breast feeding
• Use of caffeine, nicotine or over the counter cold medicines within 12 hours of the cardiac PET-MRI examination
• Use of the medication dipyridamole within 48 hrs of the cardiac PET-MRI examination