Assessment of various strategies for 18F-FET PET-guided delineation of target volumes in high-grade glioma patients

Purpose: The purpose of the study is to assess the contribution of 18F-fluoro-ethyl-tyrosine (18F-FET) positron emission tomography (PET) in the delineation of gross tumor volume (GTV) in patients with high-grade gliomas compared with magnetic resonance imaging (MRI) alone. Materials and methods: The study population consisted of 18 patients with high-grade gliomas. Seven image segmentation techniques were used to delineate 18F-FET PET GTVs, and the results were compared to the manual MRI-derived GTV (GTVMRI). PET image segmentation techniques included manual delineation of contours (GTVman), a 2.5 standardized uptake value (SUV) cutoff (GTV2.5), a fixed threshold of 40% and 50% of the maximum signal intensity (GTV40% and GTV50%), signal-to-background ratio (SBR)-based adaptive thresholding (GTVSBR), gradient find (GTVGF), and region growing (GTVRG). Overlap analysis was also conducted to assess geographic mismatch between the GTVs delineated using the different techniques. Results: Contours defined using GTV2.5 failed to provide successful delineation technically in three patients (18% of cases) as SUVmax < 2.5 and clinically in 14 patients (78% of cases). Overall, the majority of GTVs defined on PET-based techniques were usually smaller than GTVMRI (67% of cases). Yet, PET detected frequently tumors that are not visible on MRI and added substantially tumor extension outside the GTVMRI in six patients (33% of cases). Conclusions: The selection of the most appropriate 18F-FET PET-based segmentation algorithm is crucial, since it impacts both the volume and shape of the resulting GTV. The 2.5 SUV isocontour and GF segmentation techniques performed poorly and should not be used for GTV delineation. With adequate setting, the SBR-based PET technique may add considerably to conventional MRI-guided GTV delineatio

Evaluation of [18F]-choline PET/CT for staging and restaging of prostate cancer

Purpose: To evaluate the accuracy of [18F]-choline (FCH) positron emission tomography/computed tomography (PET/CT) for staging and restaging of prostate cancer. Methods: FCH PET/CT was performed in 111 patients with prostate cancer using 200MBq FCH: 43 patients [mean age 63years; mean prostrate specific antigen (PSA) 11.58μg/l] were examined for initial staging, and 68 patients (mean age 66.4years) were examined for restaging (mean PSA 10.81μg/l). FCH PET/CT results were correlated to histopathology, bone scan, morphology as revealed by magnetic resonance imaging (MRI) and CT, PET/CT follow-up and PSA follow-up after therapy. Results: FCH PET/CT scans at initial staging correctly showed no metastases in 36/38 patients undergoing radical surgery, as confirmed by PSA levels 2μg/

Characteristics and outcome of prostate cancer with PSA <4 ng/ml at diagnosis: a population-based study

Introduction: This population-based study aims to assess prognosis of prostate cancer diagnosed with prostate-specific antigen (PSA) levels <4 ng/ml in routine care. Materials and methods: We compared prostate cancer patients with low PSA values (n=59) with other prostate cancer patients (n=1330) by logistic regression and the Cox model using data from the Geneva Cancer Registry. Results: Patients with low PSA values more frequently had early-stage and well differentiated tumours. Nevertheless, 35% presented with aggressive tumour characteristics or metastases. After adjustment for other prognostic factors, prostate cancer-specific mortality was similar for both groups (hazard ratio: 1.1; 95%CI: 0.6-2.2). Conclusion: We conclude that cancer with low PSA values at diagnosis is not indolen

11C-acetate PET in the early evaluation of prostate cancer recurrence

Purpose: The first aim of the study was to investigate the diagnostic potential of 11C-acetate PET in the early detection of prostate cancer recurrence. A second aim was the evaluation of early and late PET in this context. Methods: The study population comprised 32 prostate cancer patients with early evidence of relapse after initial radiotherapy (group A) or radical surgery (group B). The median PSA of group A (n=17) patients was 6ng/ml (range 2.6-30.2) while that of group B (n=15) was 0.4ng/ml (range 0.08-4.8). Pelvic-abdominal-thoracic PET was started 2min after injection of 11C-acetate and evaluated after fusion with CT. Results: Group A: Taking a SUVmax≥2 as the cut-off, PET showed local recurrences in 14/17 patients and two equivocal results. Distant disease was observed in six patients and an equivocal result was obtained in one. Endorectal MRI was positive in 12/12 patients. Biopsy confirmed local recurrence in six of six (100%) patients. PET was positive in five of the six patients with biopsy-proven recurrences, the result in the remaining patient being equivocal. Group B: Among the 15 patients, visual interpretation was positive for local recurrences in five patients and equivocal in four. One obturator lymph node was positive. Endorectal MRI was positive in 11/15 patients and equivocal in two. Positional correlation of positive/equivocal results on PET and endorectal MRI was observed in seven of nine patients. PSA decreased significantly after salvage radiotherapy in 8/14 patients, providing strong evidence for local recurrence. PET of the eight patients responding to RT was positive in three and equivocal in two. Conclusion: 11C-acetate PET was found to be valuable in the early evaluation of prostate cancer relapse. Optimising scanning time and use of modern PET-CT equipment might allow further improvemen

ONE SHOT - single shot radiotherapy for localized prostate cancer: 18-month results of a single arm, multicenter phase I/II trial

PURPOSE To assess in a prospective, multicenter, single-arm phase I/II study the early safety and efficacy profile of single fraction urethra-sparing stereotactic body radiotherapy (SBRT) for men with localized prostate cancer. MATERIAL AND METHODS Patients with low- and intermediate-risk localized prostate cancer without significant tumor in the transitional zone were recruited. A single-fraction of 19 Gy was delivered to the prostate, with 17 Gy dose-reduction to the urethra. Intrafraction motion was monitored using intraprostatic electromagnetic transponders with intra-fraction correction of displacements exceeding 3 mm. Genitourinary (GU), gastrointestinal (GI), and sexual toxicity during the first 18 months were evaluated using the CTCAE v4.0 grading scale. Quality of life was assessed using the International Prostate Symptom Score, the Expanded Prostate Cancer Index composite 26 score, and the International Index of Erectile Function score. RESULTS Among the 45 patients recruited in 5 centers between 2017 and 2022, 43 received the single fraction without protocol deviations, and 34 had a minimal follow-up of 18 months. The worst GU toxicity was observed at day-5 after SBRT (42.5 % and 20 % with grade 1 and 2, respectively), returning to baseline at week-12 and month-6 (<3% with grade 2), with a 12 % grade 2 flare at month 18. Gl toxicity was mild in the acute phase, with no grade ≥ 2 events (12 % grade 1 at month 6). Grade-3 proctitis was observed in one patient at month 12, with < 3 % grade 2 toxicity at month 18. Mean GU and GI bother scores showed a decline at day 5, a complete recovery at month 6, and a flare between month 12 and 18. Mean PSA dropped from 6.2 ng/ml to 1.2 ng/ml at month 18 and 0.7 ng/ml at month 24. After a median follow-up time of 26 months, 3 biochemical failures (7 %) were observed at month 17, 21 and 30. CONCLUSIONS In this multicenter phase I/II trial, we demonstrated that a 19 Gy single-fraction urethra-sparing SBRT is feasible and associated with an acceptable toxicity rate, mostly returning to the baseline at week-12 and with a symptoms flare between months 12 and 18. Longer follow-up is needed to assess the potential long-term adverse effects and the disease control efficacy

Clinical impact of 18F-choline PET/CT in patients with recurrent prostate cancer

Purpose: To investigate the clinical value of 18F-fluorocholine PET/CT (CH-PET/CT) in treatment decisions in patients with recurrent prostate cancer (rPCA). Methods: The study was a retrospective evaluation of 156 patients with rPCA and CH-PET/CT for restaging. Questionnaires for each examination were sent to the referring physicians 14-64months after examination. Questions included information regarding initial extent of disease, curative first-line treatment, and the treatment plan before and after CH-PET/CT. Additionally, PSA values at diagnosis, after initial treatment, before CH-PET/CT and at the end of follow-up were also obtained from the questionnaires. Results: Mean follow-up was 42months. The mean Gleason score was 6.9 at initial diagnosis. Initial treatment was: radical prostatectomy in 110 patients, radiotherapy in 39, and combined prostatectomy and radiotherapy in 7. Median PSA values before CH-PET/CT and at the end of follow-up were 3.40ng/ml and 0.91ng/ml. PSA levels remained stable, decreased or were below measurable levels in 108 patients. PSA levels increased in 48 patients. In 75 of the 156 patients (48%) the treatment plan was changed due to the CH-PET/CT findings. In 33 patients the therapeutic plan was changed from palliative treatment to treatment with curative intent. In 15 patients treatment was changed from curative to palliative. In 8 patients treatment was changed from curative to another strategy and in 2 patients from one palliative strategy to another. In 17 patients the treatment plan was adapted. Conclusion: CH-PET/CT has an important impact on the therapeutic strategy in patients with rPCA and can help to determine an appropriate treatmen

First imaging results of an intraindividual comparison of 11C-acetate and 18F-fluorocholine PET/CT in patients with prostate cancer at early biochemical first or second relapse after prostatectomy or radiotherapy

Purpose: 18F-Fluorocholine (FCH) and 11C-acetate (ACE) PET are widely used for detection of recurrent prostate cancer (PC). We present the first results of a comparative, prospective PET/CT study of both tracers evaluated in the same patients presenting with recurrence and low PSA to compare the diagnostic information provided by the two tracers. Methods: The study group comprised 23 patients studied for a rising PSA level after radical prostatectomy (RP, 7 patients, PSA ≤3ng/ml), curative radiotherapy (RT, 7 patients, PSA ≤5ng/ml) or RP and salvage RT (9 patients, PSA ≤5ng/ml). Both FCH and ACE PET/CT scans were performed in a random sequence a median of 4days (range 0 to 11days) apart. FCH PET/CT was started at injection (307 ± 16MBq) with a 10-min dynamic acquisition of the prostate bed, followed by a whole-body PET scan and late (45min) imaging of the pelvis. ACE PET/CT was performed as a double whole-body PET scan starting 5 and 22min after injection (994 ± 72MBq), and a late view (45min) of the prostate bed. PET/CT scans were blindly reviewed by two independent pairs of two experienced nuclear medicine physicians, discordant subgroup results being discussed to reach a consensus for positive, negative end equivocal results. Results: PET results were concordant in 88 out of 92 local, regional and distant findings (Cohen's kappa 0.929). In particular, results were concordant in all patients concerning local status, bone metastases and distant findings. Lymph-node results were concordant in 19 patients and different in 4 patients. On a per-patient basis results were concordant in 22 of 23 patients (14 positive, 5 negative and 3 equivocal). In only one patient was ACE PET/CT positive for nodal metastases while FCH PET/CT was overall negative; interestingly, the ACE-positive and FCH-negative lymph nodes became positive in a second FCH PET/CT scan performed a few months later. Conclusion: Overall, ACE and FCH PET/CT showed excellent concordance, on both a per-lesion and a per-patient basis, suggesting that both tracers perform equally for recurrent prostate cancer staging

Breathing adapted radiotherapy: a 4D gating software for lung cancer

<p>Abstract</p> <p>Purpose</p> <p>Physiological respiratory motion of tumors growing in the lung can be corrected with respiratory gating when treated with radiotherapy (RT). The optimal respiratory phase for beam-on may be assessed with a respiratory phase optimizer (RPO), a 4D image processing software developed with this purpose.</p> <p>Methods and Materials</p> <p>Fourteen patients with lung cancer were included in the study. Every patient underwent a 4D-CT providing ten datasets of ten phases of the respiratory cycle (0-100% of the cycle). We defined two morphological parameters for comparison of 4D-CT images in different respiratory phases: tumor-volume to lung-volume ratio and tumor-to-spinal cord distance. The RPO automatized the calculations (200 per patient) of these parameters for each phase of the respiratory cycle allowing to determine the optimal interval for RT.</p> <p>Results</p> <p>Lower lobe lung tumors not attached to the diaphragm presented with the largest motion with breathing. Maximum inspiration was considered the optimal phase for treatment in 4 patients (28.6%). In 7 patients (50%), however, the RPO showed a most favorable volumetric and spatial configuration in phases other than maximum inspiration. In 2 cases (14.4%) the RPO showed no benefit from gating. This tool was not conclusive in only one case.</p> <p>Conclusions</p> <p>The RPO software presented in this study can help to determine the optimal respiratory phase for gated RT based on a few simple morphological parameters. Easy to apply in daily routine, it may be a useful tool for selecting patients who might benefit from breathing adapted RT.</p