Fluorodeoxyglucose uptake in the bone marrow after granulocyte colony-stimulating factor administration in patients with non-Hodgkin's lymphoma.

PURPOSE: To clarify the change in the fluorodeoxyglucose (FDG) uptake by the bone marrow over time after administration of granulocyte colony-stimulating factor (G-CSF), we evaluated the correlation between the interval from the last day of administration of G-CSF to positron emission tomography/computed tomography (PET/CT) study and spinal bone marrow accumulation in patients with non-Hodgkin's lymphoma. METHODS: A total of 127 patients with confirmed non-Hodgkin's lymphoma who underwent FDG PET within 60 days from the last administration of G-CSF were retrospectively reviewed. Thirty age-matched and sex-matched healthy controls were also included to evaluate physiological FDG uptake. PET/CT examinations were retrospectively reviewed, and maximum standardized uptake value (SUVmax) was measured by placing volumetric regions of interest over each thoracic and lumbar vertebra on PET images referring to CT images. Bone marrow SUV was defined as the mean SUVmax of the vertebra. The correlation between the interval after G-CSF and the bone marrow SUV was plotted and analyzed with polynomial approximation. RESULTS: In controls, physiological bone marrow SUV of the spine was determined. In patients with lymphoma, bone marrow SUV decreased over time and reached a plateau at about 14 days after G-CSF administration, and this was higher by 5% than the plateau at 10 days. SUV declined to the 'physiological range', that is, mean+1 standard deviation of patients, at about 7 days. CONCLUSION: For a PET/CT study, an interval of 10 days after G-CSF administration is recommended to minimize the influence of G-CSF on the bone marrow when evaluating treatment response in patients with non-Hodgkin's lymphoma.

Decreased brain FDG uptake in patients with extensive non-Hodgkin's lymphoma lesions.

OBJECTIVE: Faint brain [(18)F]fluoro-2-deoxyglucose (FDG) uptake has sporadically been reported in patients with FDG-avid large or diffusely extended tumors. The purpose of this study was to investigate whether there is a correlation between massive tumor uptake and decreased brain uptake on FDG positron emission tomography/computed tomography (PET/CT). METHODS: Sixty-five patients with histologically confirmed non-Hodgkin's lymphoma who underwent FDG-PET/CT were enrolled. Thirty control subjects were also included to evaluate normal brain FDG uptake. PET/CT examinations were retrospectively reviewed. The volumetric regions of interest were placed over lesions by referring to CT and PET/CT fusion images to measure mean standardized uptake value (SUVavg). The products of SUVavg and tumor volume were calculated as total glycolytic volume (TGV). The maximum SUV (SUVmax) and SUVavg were measured in the cerebrum and cerebellum. The values of TGV and brain FDG uptake were plotted and analyzed with a linear regression method. RESULTS: In the lymphoma patients, there were statistically significant negative correlations between TGV and brain SUVs. CONCLUSION: Demonstrating a significant negative correlation between TGV and brain uptake validated the phenomenon of decreased brain FDG uptake. Diversion of FDG from the brain to the lymphoma tissue may occur during the FDG accumulation process. Recognition of this phenomenon prevents unnecessary further neurological examinations in such cases.

[Accuracy of dynamic multileaf position and influence of beam profile according to change in dose monitor unit in QA plan of intensity modulated radiotherapy].

The number of dose monitor units in IMRT QA plans differs form the actual conditions of IMRT in dosimetry for verification of dynamic multileaf-IMRT (DMLC-IMRT). We measured the accuracy of the position of the dynamic multileaf collimator and the dose profile for various numbers of dose monitor units, and verified the accuracy of dosimetry in an IMRT QA plan. The accuracy of the position of the dynamic multileaf collimator was measured by using the software of the external irradiation device, and the dose profile was measured by using the semiconductor profiler. Deviation in the position of the dynamic multileaf collimator increased as the number of dose monitor units decreased. When deviation in the position of the dynamic multileaf collimator was large and the gap width of the multileaf collimator was narrow, the change in dose profile was large. Therefore, verification of IMRT QA plans requires a phantom and measurement device close to the actual conditions of IMRT.