Evaluation of decreased uptake of 18F-fluorodeoxyglucose in the cerebral cortex of patients with intracranial non-Hodgkin's lymphoma lesions through PET/CT.

Abstract

This study aims to investigate whether basal ganglia can be utilised as reference for measuring ratios between standardised uptake values (SUV), namely, SUVmax and SUVmean, of 18F-fluoro-deoxyglucose (18F-FDG) uptake, in the ipsilateral cerebral cortex and basal ganglia of patients with non-Hodgkin's lymphoma lesions. Fifty-three patients with pathologically confirmed highly metabolic non-Hodgkin's lymphoma were retrospectively analysed; these patients were subjected to treatment strategy and underwent positron emission tomography/computed tomography (PET/CT). Nineteen of the patients who improved after the treatment were re-examined by PET/CT. PET/CT simultaneity was performed on 12 normal volunteers as the control group. SUVmax and SUVmean in the cerebral cortex and basal ganglia (head of caudate nucleus and lenticular nucleus) were evaluated by ganglia was also calculated. The ratios were compared between patients and the control group as well as before and after the treatment. The ratios between the SUVmax of 18F-FDG uptake were 1.03±0.16 (range 0.50-1.51, left) in the ipsilateral cerebral cortex and 1.02±0.16 (range 0.50-1.31, right) in the basal ganglia of 53 patients with non-Hodgkin's lymphoma; the corresponding ratios in the 12 controls were 1.09±0.11 (range 0.99-1.21, left) and 1.09±0.09 (range 1.00-1.24, right), respectively. The ratios between the SUVmean and 18F-FDG uptake in the ipsolateral cerebral cortex and basal ganglia were 0.76±0.09 (range 0.50-1.07, left) and 0.76±0.09 (range 0.48-0.98, right), respectively, which were lower than those in the control group [0.93±0.06 (range 0.83-0.99, left) and 0.92±0.05 (range 0.84-0.99, right), respectively]. For patients effectively treated, the ratios between the SUVmax in the ipsolateral cerebral cortex and basal ganglia were 1.08±0.13 (range 0.94-1.36, left) and 1.08±0.13 (range 0.88-1.31, right) before the treatment; these values were similar to 1.11±0.13 (range 0.85-1.36, left) and 1.09±0.11 (range 0.90-1.32, right) obtained in the ipsolateral cerebral cortex and basal ganglia of the patients after the treatment, respectively. The ratios between the SUVmean in the ipsolateral cerebral cortex and basal ganglia were 0.78±0.06 (range 0.68-0.93, left) and 0.78±0.06 (range 0.69-0.95, right) in the patients before the treatment; these ratios were lower than those in post-treatment patients [0.90±0.06 (range 0.74-1.00, left) and 0.90±0.07 (range 0.72-1.00, right), respectively], respectively. High levels of 18F-FDG metabolism in patients with non-Hodgkin's lymphoma may decrease glucose uptake in the cerebral cortex (diversion of 18F-FDG from the cerebral tissue to the lymphoma tissue); this phenomenon may be reversed with effective therapy for lymphoma. The ratio with 18F-FDG metabolism in basal ganglia could be used as reference to quantify and monitor glucose metabolism in cerebral tissues during the course of lymphoma.