Utility of Short-Acting Intravenous Insulin Therapy in Preparation of F-18 Fluorodeoxyglucose Positron Emission Tomography Computed Tomography Scan in Cancer Patients Incidentally Detected with High Blood Glucose Levels on the Day of Test

BACKGROUND: In diabetic (DM) patients, hyperglycemia degrades image quality in F-18 FDG PET CT by altering bio-distribution of FDG in the body and augmenting soft tissue and muscular uptake. We intend to evaluate the use of short acting I.V insulin in minimising the rescheduling of patients detected with FBG>160 mg/dL on the day of scan. AIM AND OBJECTIVES: To show the utility of short acting IV insulin therapy in preparation of cancer patients incidentally detected with high blood glucose levels for F-18 FDG PET CT scan, (>160mg/dL) and to compare the obtained image quality with patients detected with fasting blood glucose level (FBG) <100mg/dL and <160 mg/dL, using visual and semi quantitative methods. MATERIAL AND METHODS: 613 cancer patients referred for PET CT were divided into 3 groups, Group I (n=30): known diabetics (DM) or incidentally diagnosed with FBG >160 mg/dL, Group II (n=349): DM patients with FBG <160 mg/dL (100-160mg/dL), Group III (n=234): Non DM patients FBG <100mg/dL. In Group I short acting insulin was given intravenously using a sliding scale, post insulin after 90 minutes F-18 FDG (radiotracer) injection was given and PETCT scan was obtained 60 mins post radiotracer injection. Qualitative image analysis was done using biodistribution score and quantitative analysis was done by chi square test, ANOVA (analysis of variance) and paired t-test. RESULTS: In group I patients post insulin there was significant decrease in FBG levels (216±22.2 to 136±13.4mg/dL) and acceptable image quality. Comparison of quantitative parameters (mean and maximum SUV calculated by drawing ROI around brain, heart, liver, muscle, subcutaneous fat) among the 3 groups showed significant intergroup difference with p value <0.05. CONCLUSION: This short acting I.V insulin protocol is safe and can be used to obtain optimal quality F-18 FDG PET CT scan images by alleviating the need for rescheduling patients though they present with high glucose levels.