| 1,000 mg given at least 30 min prior to injection) to prevent possible thyroid uptake of free radioactive iodine. | |
| ## Information Pertinent to Performance of the Procedure | |
| - Patient history with particular focus on previous surgery and/or radiation therapy as well as current and past neurological or psychiatric status.- History of diabetes, fasting state.- Information regarding recent morphological imaging studies (CT, MRI).- Current medication and when last taken, especially psychotropic pharmaceuticals. These may influence regional metabolic rate of glucose (rCMRGI).- Patient's ability to lie still for 20-40 min for PET to \(\sim 1\) h for SPECT. | |
| ## Precautions and Conscious Sedation | |
| - Continuous supervision of the patients during the whole scanning procedure is necessary. This is especially important for patients with tumor associated seizures.- In uncooperative patients, it may be worthwhile to apply conscious sedation (e.g., by a short acting benzodiazepine such as i.v., midazolam). For FDG, administration should take place at least 20 min after tracer injection, preferably starting only a few minutes before data acquisition.- Appropriate monitoring (pulse-oximetry) should be performed to recognize the possibility of cardiopulmonary depression and appropriate antidote/emergency backup should be foreseen. Doses of sedation should be reduced in elderly patients. | |
| ## Radiopharmaceutical | |
| ## Radiopharmaceutical | |
| - \(^{[18}\mathrm{F}]\mathrm{Fluoro-2-deoxyglucose}\) (FDG). | |
| - \(3 - [^{123}\mathrm{I}]\) Iodo- \(\alpha\) -methyl-L-tyrosine (IMT). | |
| - [Methyl-\(^{11}\mathrm{C}\) ]-L-methionine (MET). | |
| - \(O - (2 - [^{18}\mathrm{F}]\) Fluoroethyl)-L-tyrosine (FET). | |
| ## Recommended Dosage | |
| The dose recommendations for FDG, MET, and FET mentioned here are valid for full ring dedicated PET- cameras with BGO- crystals in 3D- mode. | |
| - FDG: in adults, 125-250 MBq (typically 150 MBq) in 3D-mode. In children, 2-4 MBq/kg in 3D-mode with a minimum of 10 MBq in newborn infants.- IMT: 100-400 MBq (typically 185 MBq).- MET: 200-250 MBq.- FET: 200-250 MBq. | |
| The administered dose may increase using 2D- mode and vary for other systems according to differences in sensitivity. For the radiolabeled amino acids, the activity to be administered to children should be a fraction of the adult activity calculated from body weight according to the factors given by the EANM Pediatric Task Group. | |
| ## Radiation Dosimetry (Table 2.1) | |
| ## Radiation Dosimetry of Brain Transmission Scans | |
| Based on transmission scans of 10 min and CT- based scans of 5- 10 s, the effective doses per scan are: 20- 30 μSv for Germanium- based transmission, \(\sim 20\) μSv for low- dose high- speed CT, and between 220 and 450 μSv for high- quality CT. |