Imaging with non-FDG PET tracers: outlook for current clinical applications

Apart from the historical and clinical relevance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG), various other new tracers are gaining a remarkable place in functional imaging. Their contribution to clinical decision-making is irreplaceable in several disciplines. In this brief review we aimed to describe the main non-FDG PET tracers based on their clinical relevance and application for patient care

Dual-Phase PET-CT to Differentiate [F-18]Fluoromethylcholine Uptake in Reactive and Malignant Lymph Nodes in Patients with Prostate Cancer

PURPOSE: To investigate whether time-trends of enhanced [(18)F]Fluoromethylcholine ([(18)F]FCH) in lymph nodes (LN) of prostate cancer (PCa) patients can help to discriminate reactive from malignant ones, and whether single time point standardized uptake value (SUV) measurements also suffice. PROCEDURES: 25 PCa patients with inguinal (presumed benign) and enlarged pelvic LN (presumed malignant) showing enhanced [(18)F]FCH uptake at dual-phase PET-CT were analyzed. Associations between LN status (benign versus malignant) and SUV(max) and SUV(meanA50), determined at 2 min (early) and 30 min (late) post injection, were assessed. We considered two time-trends of [(18)F]FCH uptake: type A (SUV early > SUV late) and type B (SUV late ≥ SUV early). Histopathology and/or follow-up were used to confirm the assumption that LN with type A pattern are benign, and LN with type B pattern malignant. RESULTS: Analysis of 54 nodes showed that LN status, time-trends, and 'late' (30 min p.i.) SUV(max) and SUV(meanA50) parameters were strongly associated (P<0.0001). SUV(max) relative difference was the best LN status predictor. All but one inguinal LN showed a decreasing [(18)F]FCH uptake over time (pattern A), while 95% of the pelvic nodes presented a stable or increasing uptake (pattern B) type. CONCLUSIONS: Time-trends of enhanced [(18)F]FCH uptake can help to characterize lymph nodes in prostate cancer patients. Single time-point SUV measurements, 30 min p.i., may be a reasonable alternative for predicting benign versus malignant status of lymph nodes, but this remains to be validated in non-enlarged pelvic lymph nodes

In vivo uptake of [C-11]choline does not correlate with cell proliferation in human prostate cancer

Purpose: Prostate cancer is the second leading cause of death from cancer among US men. Positron emission tomography (PET) with [C-11] choline has been shown to be useful in the staging and detection of prostate cancer. The background of the increased uptake of choline in human prostate cancer is not completely understood. The aim of this study was to prospectively investigate the relationship between the [C-11] choline uptake and the cell proliferation in human prostate cancer. Methods: Prostate cancer tissue from 18 patients who had undergone a radical prostatectomy for histologically proven disease was studied. An [C-11] choline PET scan was performed prior to surgery. Post-prostatectomy specimens were prepared and stained with the antibody MIB-1 for Ki-67, which depicts proliferation. Two independent observers counted the amount of stained nuclei per specimen. Results: Prostate cancer showed Ki-67 staining and high uptake of [C-11] choline. Statistical analysis showed no significant correlation between [C-11] choline uptake and Ki-67 staining (R = 0.23; P = 0.34). No significant relationships were found between the uptake of [C-11] choline (SUV) and either preoperative PSA (R = 0.14; P = 0.55) or Gleason sum score (R = 0.28; P = 0.25). Conclusion: In vivo uptake of [C-11] choline does not correlate with cell proliferation in human prostate cancer as depicted by Ki-67. Our results suggest that a process other than proliferation is responsible for the uptake of [C-11] choline in prostate cancer

[11C]choline PET for the intraprostatic tumor characterization and localization in recurrent prostate cancer after EBRT

Aim. This study focuses on the potential role of [C-11] choline positron emission tomography (PET) for the intraprostatic tumor characterization and localization in recurrent prostate cancer after EBRT. Methods. This retrospective study was conducted in patients who were being followed up after EBRT for histological proven prostate cancer. We selected the patients with a local recurrence by [C-11]choline PET/CT fusion. The results of PET were compared with the results of histology and with clinical follow-up. Results. Forty-two patients with a local recurrence suggested by PET were included in this study. According to PET results: of the 42 patients, 15 (36%) had a focal recurrence, 27 (64%) showed a diffuse recurrence. The overall concordance of PET with histology concerning detection of recurrence was 76% (32 patients had positive PET results and positive biopsies). We confirmed the local recurrence as visualized by PET in 37/42(88%) patients using a composite reference with histology and clinical follow up after local salvage treatment. The concordance of the intraprostatic distribution of the tumor with PET with histology from transrectal prostate biopsies (median biopsies 7, range 4-12) was 47% (7/15) in unilateral cases and 41% (11/27) in bilateral cases. No significant differences were seen between the 2 groups in serum PSA at time of PET (P=0.509) and SUV (P=0.739) using Student's t-test. Conclusion. Intraprostatic characterization of recurrent prostate cancer after EBRT with C-11-choline PET is feasible at present but shows a moderate concordance with routine transrectal prostate biopsies. The accuracy is too low for the routine use of this modality in the present scenario