Normal uptake of 18F-FDG in the testis: an assessment by PET/CT.
OBJECTIVE
The aim of this study was to assess the physiological uptake of 18F-fluoro-2-deoxyglucose (FDG) by an apparently normal testis with combined positron emission tomography-computed tomography (PET/CT) and its correlation with age, blood glucose level, and testicular volume.


METHODS
The testicular uptake of 18F-FDG, expressed as the standardized uptake value (SUV), was measured on PET/CT images in 203 men. The correlation between SUV and age, blood glucose level, and testicular volume was assessed.


RESULTS
The SUV in the total of 406 testes was 2.44 +/- 0.45 (range 1.23-3.85). The SUV was 2.81 +/- 0.43 (2.28-3.85) for 30-39 years (n = 12), 2.63 +/- 0.45 (1.77-3.75) for 40-49 years (n = 64), 2.46 +/- 0.35 (1.44-3.15) for 50-59 years (n = 82), 2.51 +/- 0.41 (1.50-3.46) for 60-69 years (n = 86), 2.43 +/- 0.47 (1.42-3.29) for 70-79 years (n = 86), and 2.18 +/- 0.45 (1.23-3.03) for 80-89 years (n = 76). When we calculated the mean SUV of bilateral testes in each patient, there were significant statistical differences between those in the age group of 30-39 years and 80-89 years, 40-49 years and 80-89 years, and 50-60 years and 80-89 years, when using an unpaired test with Bonferroni correction. The laterality index (|L - R|/(L + R) x 2) in 203 men was 0.066 +/- 0.067 (0-0.522). There was a mild correlation between the mean SUV and age (r = -0.284, P < 0.001) as well as between the mean SUV and mean volume (r = +0.368, P < 0.001). There was no correlation between the mean SUV and glucose blood level (r = -0.065, P = 0.358).


CONCLUSIONS
Some uptake of FDG is observed in the normal testis and declines slightly with age. Physiological FDG uptake in the testis should not be confused with pathological accumulation.
Kitajima
Kazuhiro
K
Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan. kazu10041976@yahoo.co.jp
Nakamoto
Yuji
Y
Senda
Michio
M
Onishi
Yumiko
Y
Okizuka
Hiromi
H
Sugimura
Kazuro
K
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics* / Q000592:standards*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000592:standards; D013382:Subtraction Technique; D013737:Testis / Q000033:anatomy & histology / Q000378:metabolism*; D014057:Tomography, X-Ray Computed
D001786:Blood Glucose; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18