¹⁸F‐choline and/or ¹¹C‐acetate positron emission tomography: detection of residual or progressive subclinical disease at very low prostate‐specific antigen values (<1 ng/mL) after radical prostatectomy

Abstract

OBJECTIVES To assess the value of positron emission tomography (PET)/computed tomography (CT) with either 18F‐choline and/or 11C‐acetate, of residual or recurrent tumour after radical prostatectomy (RP) in patients with a prostate‐specific antigen (PSA) level of <1 ng/mL and referred for adjuvant or salvage radiotherapy. PATIENTS AND METHODS In all, 22 PET/CT studies were performed, 11 with 18F‐choline (group A) and 11 with 11C‐acetate (group B), in 20 consecutive patients (two undergoing PET/CT scans with both tracers). The median (range) PSA level before PET/CT was 0.33 (0.08–0.76) ng/mL. Endorectal‐coil magnetic resonance imaging (MRI) was used in 18 patients. Nineteen patients were eligible for evaluation of biochemical response after salvage radiotherapy. RESULTS There was abnormal local tracer uptake in five and six patients in group A and B, respectively. Except for a single positive obturator lymph node, there was no other site of metastasis. In the two patients evaluated with both tracers there was no pathological uptake. Endorectal MRI was locally positive in 15 of 18 patients; 12 of 19 responded with a marked decrease in PSA level (half or more from baseline) 6 months after salvage radiotherapy. CONCLUSIONS Although 18F‐choline and 11C‐acetate PET/CT studies succeeded in detecting local residual or recurrent disease in about half the patients with PSA levels of <1 ng/mL after RP, these studies cannot yet be recommended as a standard diagnostic tool for early relapse or suspicion of subclinical minimally persistent disease after surgery. Endorectal MRI might be more helpful, especially in patients with a low likelihood of distant metastases. Nevertheless, further research with 18F‐choline and/or 11C‐acetate PET with optimal spatial resolution might be needed for patients with a high risk of distant relapse after RP even at low PSA values.

18F-fluorocholine for prostate cancer imaging: a systematic review of the literature

“…Dynamic acquisition over the pelvis followed by a whole-body PET or PET/CT static acquisition including the pelvis has been proposed as allowing visualization of pelvic disease without interference from bladder uptake (dynamic imaging) while allowing maximum sensitivity for distant disease (delayed whole-body PET or PET/CT). 20,21,24,34,35,37,38,42,57 Early time points for imaging (0-15 min post-intravenous injection) and/or delayed imaging time points (30,40,45,60, 90-120 and 65-200 min post-intravenous injection) have been also described in the published literature. 22,23,[27][28][29][30][31][32][33]36,39,40,41,[43][44][45][46][47][48][49][50][51][52][54][55][56] 34 16…”

“…Seven studies detailing the radiosynthesis of 18 F-FCH, preclinical and early clinical dosimetry and biodistribution in humans were identified. [20][21][22][23][24][25][26] Clinical studies included six articles for evaluation of local disease, [27][28][29][30][31][32] five articles for evaluation of nodal disease, 30,[33][34][35][36] six articles for bone metastases, including evaluation of treatment response, 30,34,[37][38][39][40] 12 articles for biochemical recurrence 34,[36][37][38][40][41][42][43][44][45][46][47] and two articles evaluating 18 F-FCH in castrate-resistant patients. 39,48 Seven studies evaluated 18 F-FCH for defining intra-prostatic lesions or limited lymph node recurrence for dose-escalated radiotherapy.…”

“…In the setting of biochemical recurrence, generally the performance of 18 F-FCH PET/CT seems to be higher among patients with higher PSA at the time of recurrence, shorter PSA doubling time or higher initial Gleason grade. 34,[36][37][38][41][42][43][44][45][46][47] For instance, Cimitan et al 41 found positive 18 F-FCH scans in 54 patients examined for rising PSA post-radical prostatectomy (n ¼ 58), radical radiotherapy (n ¼ 21) or while on hormones (n ¼ 21). They noted that the 18 F-FCH scans were rarely (3/38) positive among patients with PSA o4 ng ml À1 and initial Gleason grade p7, whereas all patients with a PSA 44 ng ml À1 and Gleason score 47 had positive scans.…”

“…40 Although the overall sensitivity for detecting any recurrence with 18 F-FCH imaging at PSA levels X2-5 ng ml À1 seems to be acceptable (X80%), the sensitivity for detection of prostate bed and small lymph node recurrences at PSA levels o2-5 ng ml À1 is lower (E50%). 34,[41][42][43][44][45] This may reflect the fact that isolated local recurrence is more likely at lower PSA levels and these recurrences may be more difficult to detect owing to challenges in distinguishing between prostate bed uptake and bladder accumulation of tracer, particularly for small volume recurrences. 34,36,[41][42][43][44][45] For example, in a series of 84 PCa patients, Panebianco et al 46 noted superior performance of 3 T combined 1 H-MRI and MR spectroscopy vs 18 F-FCH PET/CT for small volume (mean diameter ¼ 6 mm) and low PSA value (0.2-2 ng ml À1 ) recurrences, but comparable performance for larger volume local recurrence (mean diameter ¼ 13.3 mm).…”

“…Radiotherapy dose escalation to the whole prostate has been shown to be associated with improved disease control, but at the cost of higher gastrointestinal and genitourinary toxicity. 59 Histopathology studies demonstrating that most PCa men 42 34 o5 PET/CT Vees et al 45 11 o1 PET/CT Pelosi et al 43 56 0.1-39 w PET/CT Husarik et al 36 68 0.36-100 w PET/CT 2. Lower sensitivity for detection of recurrence in PCa patients with lower PSA values (o2-5 ng ml À1 ), and small lesions (o10 mm).…”