half-dose radiopharmaceutical in wide beam reconstruction

Conditions: Myocardial Infarction; Ischemic Heart Disease

Summary: this study is recruiting patients already scheduled for a single photon emission computed tomography myocardial perfusion imaging (spect-mpi) test. spect-mpi is a nuclear imaging technique that uses a radioactive substance, or radiotracer, and special equipment to create three-dimensional (3d) images of the heart. radiotracer is a radioactive dye that will make the structures of the heart visible and is routinely used to view blood flow in the heart, scan for damaged heart tissue, or assess heart function. for a routine spect-mpi test, the radiotracer is given in one dose at the beginning of the test, followed by taking resting images of the heart. for this study, researchers would like to administer half of the radiotracer, obtain resting images, administer the remainder of the radiotracer and obtain a second set of resting images. participants will receive the same amount of radioactive material that would normally be given for this test; however, it will be administered in two half-doses. participation in this study will add about 30 minutes to the time it takes to complete the routine test. the investigators expect to enroll about 160 subjects in this study at northwestern.

subjects in this study will proceed to the nuclear cardiology laboratory for their scheduled nuclear stress test. after informed consent is obtained, the study doctor or research staff member will ask detailed questions about the subject's current health, medications and medical history, and the subject's medical chart will be reviewed including results of any previous nuclear images. for the test, a small catheter (tube) will be placed in a vein in the subject's arm to administer the radioactive imaging agent, tc-99m sestamibi. subjects will be given half (1/2) of the normal tc-99m sestamibi dose and then the study staff will obtain resting images pictures of the heart. after this set of images, the subject will be given the remaining half of the radioactive imaging agent followed by a second set of images. after this, the subject will then undergo the stress portion of the test in the usual manner as prescribed by the referring physician.

Eligibility criteria:
inclusion criteria: * patients over the age of 18 years * undergoing nuclear stress testing * history of myocardial infarction, cardiomyopathy, heart failure or prior nuclear studies with resting perfusion defects exclusion criteria: * unwilling or unable to undergo an additional resting spect acquisition * clinical contraindications to nuclear stress testing including acute myocardial infarction * for patients undergoing exercise treadmill stress testing: * left bundle branch block or artificial ventricular pacemaker * for patients undergoing regadenoson (lexiscan) stress testing: * moderate to severe chronic obstructive pulmonary disease or asthma, second- or third degree atrioventricular block or sinus node disease (unless patients have a functioning artificial pacemaker), known hypersensitivity to aminophylline or adenosine * inability to give informed consent

Keywords: spect mpi tomography, emission-computed, single-photon wide beam reconstruction