Going Nuclear with Amino Acids and Proteins - Basic Biochemistry and Molecular Biology Primer for the Technologist

In recent years, there has been an influx of new tracers into the field of nuclear medicine and molecular imaging. Most of these tracers that have been FDA approved for clinical imaging exploit various mechanisms of protein biochemistry and molecular biology to bring about their actions, such as amino acid metabolism, protein folding, receptor-ligand interactions, and surface transport mechanisms. In this review, we attempt to paint a clear picture of the basic biochemistry and molecular biology of protein structure, translation, transcription, post-translational modifications, and protein targeting, in the context of the various radiopharmaceuticals currently used clinically, all in an easy-to-understand language for entry level technologists in the field. Tracer characteristics, including indications, dosage, injection-to-imaging time, and the logic behind the normal and pathophysiologic biodistribution of these newer molecular tracers, are also discussed.

Diagnosis of perioperative myocardial infarction after coronary artery bypass

The diagnosis of perioperative myocardial infarction (POMI) in patients undergoing coronary artery bypass is uncertain because the criteria of infarction are unclear. Fifty patients who underwent coronary artery bypass were evaluated preoperatively and postoperatively with serial ECGs, creatine phosphokinase (CPK), isoenzyme determinations, and technetium pyrophosphate myocardial scans. Clinical evaluation correlated with exercise testing and postoperative angiography supported the diagnosis in questionable cases. Thirty-five patients (70%) had no evidence of POMI by any criteria, and 2 patients (4%) had unequivocal evidence of infarction by all criteria. Our studies indicate the complexities of diagnosing POMI. We believe that the serially recorded ECG is the most useful diagnostic technique. CPK isoenzyme determinations may be useful but are difficult to interpret in the operative setting. Preoperative cardiac scans are necessary so as to avoid a high incidence of false-positive scans postoperatively. In doubtful cases, postoperative coronary arteriography and left ventricular angiography may provide the most definitive information.