Association between [18F]fluorodeoxyglucose uptake and postoperative histopathology, hormone receptor status, thymidine labelling index and p53 in primary breast cancer: a preliminary observation.

To investigate the possible role of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) in the prognostic evaluation of primary breast cancer, we studied 86 patients with T1-3 (TNM classification) breast tumours before surgery and compared the tumour FDG uptake, calculated as a standardized uptake value (SUV), with postoperative histopathological findings, steroid hormone receptor status of the tumour, thymidine labelling index (LI) and tissular expression of p53. SUV was significantly higher in infiltrating ductal carcinomas (n = 68; median SUV = 5.6) than in lobular ones (n = 18; median SUV = 3.8), and in grade 3 carcinomas (n = 26; median SUV = 6.2) than in grade 1-2 ones (n = 60; median SUV = 4.9). Moreover, SUV was significantly higher in carcinomas with high levels of p53 (n = 12; median SUV = 9.5) than in those with low levels (n = 48; median SUV = 4.25). By contrast, there was no significant correlation between SUV and the steroid hormone receptor status or LI of tumours. Our data demonstrate that FDG uptake, expressed as SUV, is associated with certain prognostic factors in breast cancer, such as histopathological grading and p53 expression, which can be assessed only by means of postoperative in vitro examinations. Hence, the information provided by FDG-PET is to some extent related to relevant information on tumour biology. The clinical value of these data will have to be confirmed by analysis of the independence of SUV from other prognostic factors by means of a multivariate analysis performed on a larger series of patients with adequate follow-up. If SUV is confirmed as an independent variable, FDG-PET could assume an important role in the determination of appropriate therapeutic strategies for primary breast cancer.

A simple and semi-automated system for increasing the recovery of aqueous [18F] fluoride from target.

A simple semi-automated apparatus is described for rinsing the transport line from the [18F] fluoride. target to the hot-cell after recovery of aqueous [18F] fluoride. The additional activity thus recovered can then be added to that previously trapped on Dowex 1X8 (CO3=) or, alternatively, diverted to a second vial for other uses such as research, PET-camera calibration or bone investigations by PET. Inclusion of the target chamber in the rinsing procedure increased the additional recovery of activity up to ca. 15%, without a noticeable effect on the isotopic integrity of the recovered [18O]H2O.

The influence of blood glucose levels on [18F]fluorodeoxyglucose (FDG) uptake in cancer: a PET study in liver metastases from colorectal carcinomas.

AIMS AND BACKGROUND: To study the influence of blood glucose levels on the clinical reliability of positron emission tomography (PET) with [18F]-2-fluoro-2-deoxy-D-glucose (FDG) in the detection of liver metastases from colorectal carcinomas and in the analysis of tumor uptake of FDG. METHODS: After having given their informed consent, 8 patients with 20 liver metastases (mean size, 31.5 mm; range, 10-75 mm) detected by means of CT were submitted to a first FDG-PET examination under fasting conditions and, 2 days later, to a second FDG-PET examination performed after i.v. infusion of a glucose solution (4 mg/kg/min for 2 hrs). The results of the two studies were compared in each patient, considering both the localization of the metastases and the FDG uptake in the lesions. A non-kinetic method was used, calculating the Standardized Uptake Value (SUV). RESULTS: All 20 metastases were clearly visible on FDG-PET under fasting conditions. Moreover, in 2 patients FDG-PET detected a number of unknown liver metastases. The blood glucose levels after glucose infusion were significantly higher than the levels under fasting conditions, 158 +/- 13.8 mg/100 ml (mean +/- sd) and 92.4 +/- 10.2, respectively (P < 0.001), and the quality of the FDG-PET images showed a marked deterioration. FDG-PET was unable to detect 6 of the 20 lesions and another 10 lesions were localized less clearly. Moreover, 80% of the unknown liver metastases were not detected after glucose loading. The SUVs of metastases decreased from 9.4 +/- 5.7 (mean +/- sd) under fasting conditions to 4.3 +/- 8.3 after glucose loading (P < 0.001). CONCLUSIONS: FDG-PET studies may be particularly unreliable under conditions of high levels of blood glucose. Therefore, patients entering FDG-PET studies should fast, and blood glucose concentration needs to be taken into account when evaluating FDG uptakes in follow-up studies.

Radiation dose to technicians per nuclear medicine procedure: comparison between technetium-99m, gallium-67, and iodine-131 radiotracers and fluorine-18 fluorodeoxyglucose.

The aim of this study was to determine the non-extremity gamma dose received by a technician while performing an ordinary nuclear medicine procedure or a static (i.e. without blood sampling) fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) study. The dose per patient was measured by means of a commercial electronic pocket Geiger Mueller dosimeter, worn in the upper left pocket of the overalls. This was previously tested by exposure to known point sources of technetium-99m, gallium-67, iodine-131 and fluorine-18 in the air. A further test was performed with 99mTc, 131I and 18F sources inserted in a water phantom to simulate the condition of high scattering degradation of the primary radiation due to the patient's tissues. Subsequently, the dose was measured by two technicians for a total of 314 clinical cases, covering the most common nuclear medicine procedures, including 44 static, two-level FDG PET studies with repositioning of the patient on the couch between the transmission and the emission scan and seven whole-body PET studies. The dose read by the dosimeter was corrected for environmental background and for detector efficiency measured with sources in the air. For a limited subset of cases, the time spent close to patients was also measured. Doses were then estimated by a crude non-absorbing point source approximation and by using experimental dose rates. A comparison between experimental and estimated doses, as well as with previously published data, completed the work. For most of the conventional procedures, the measured dose per procedure proved to be within the range 0.2-0.4 microSv, except for equilibrium angiocardioscintigraphy (1.0+/-0.5 microSv) and 99mTc-sestamibi single-photon emission tomography (1. 7+/-1.0 microSv). Comparison with data published in the last 20 years shows that our values are generally lower. The current more favourable working conditions are a result of technological improvements (for instance two-head gamma cameras capable of whole-body studies), and safer shielding and distance from patients. Two-level PET gave 11.5+/-4.4 microSv and whole-body PET 5.9+/-1.2 microSv. In a subset of patients these values could be subdivided into the separate contributions from each phase of the procedure. They were: 0.11+/-0.04 microSv for daily quality assurance, 2.9+/-3.0 microSv for two transmission scans, 0.3+/-0.1 microSv for syringe preparation, 2.8+/-1.8 microSv for injection and escorting the patient to the waiting room, 1.7+/-1.5 microSv for a whole-body emission scan, 7.7+/-5.2 microSv for two emission scans, and 0.8+/-0. 2 microSv for patient departure. The higher value from PET by comparison with conventional procedures is attributable to the higher specific gamma constant of 18F, as well as the longer time required for accurate positioning.