Imaging evaluation of prostate cancer with 18F-fluorodeoxyglucose PET/CT: utility and limitations

Abstract

Prostate cancer is a major public health problem in developed countries. The remarkable biological and clinical heterogeneity of prostate cancer provides unique opportunities as well as challenges for the diagnostic imaging evaluation of this prevalent disease. The disease is characterized by a natural history that ranges from localized slowly growing hormone-dependent tumor progressing to metastatic hormone-refractory disease. PET is an ideal imaging tool for noninvasive interrogation of the underlying tumor biology. (18)F-FDG is the most common PET radiotracer used for oncological applications based upon elevated glucose metabolism in malignant tissue in comparison to normal tissue. FDG uptake in prostate cancer depends on tumor differentiation with low accumulation in well-differentiated tumors and high uptake in aggressive poorly differentiated tumors. Cumulative current evidence suggests that FDG PET may be useful in detection of disease in a small fraction of patients with biochemical recurrence, in the imaging evaluation of extent and treatment response in metastatic disease and in prediction of patient outcome.

Fig. 1

Biochemical recurrence of prostate cancer after curative prostatectomy (serum PSA=2.2 ng/mL, initial Gleason score 9). Note the 1 cm hypermetabolic metastatic left paraaortic lymph node (arrowhead) on the axial fused FDG PET/CT image.

Fig. 2

Treatment response evaluation with FDG PET/CT. CT at bone window level (left) and fused PET/CT (right) images demonstrate hypermetabolic lesions with little or no structural abnormality involving the right posterior ilium (SUVmax 5.5) and left L5 (SUVmax 3.6) before therapy (top panel, serum PSA=67.4 ng/mL) that become metabolically inactive (SUVmax 1.3) and sclerotic after successful chemotherapy (bottom panel, serum PSA = 0.3 ng/mL).

Fig. 3

Prognostic utility of FDG PET/CT in metastatic prostate cancer. Maximum intensity projection PET images show clinical states of castrate-sensitive predominantly lymph node disease at baseline (left panel) developing into castrate-resistant predominantly bone metastatic disease after 12 months (right panel). The patient died at 28.5 months after the baseline scan.