The effectiveness of low-dose intravenous insulin boluses to improve study quality in F-18 FDG myocardial scans is investigated. Seventeen patients were imaged using a protocol in which only diabetic patients with fasting blood glucose levels > 8 mmol/l were given insulin. Fifty-three patients were imaged using a protocol in which all patients were given 1-3 IU intravenously of insulin immediately before F-18 FDG injection, based on fasting blood glucose levels. Scan quality was rated as poor, good, or excellent. Using the conventional protocol, 29% of the scans were poor quality (uninterpretable), 47% were good, and 23% were excellent. Using the low-dose intravenous insulin boluses protocol, 2% were poor, 53% were good, and 45% were excellent (P = 0.01). There were no significant differences in the proportion of diabetic patients, age, or fasting blood glucose levels. Low-dose intravenous insulin bolus is an easy and safe method of improving myocardial F-18 FDG scan quality in nondiabetic and diabetic patients.