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

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

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 (18)F-fluoro-ethyl-tyrosine ((18)F-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 (18)F-FET PET GTVs, and the results were compared to the manual MRI-derived GTV (GTV(MRI)). PET image segmentation techniques included manual delineation of contours (GTV(man)), a 2.5 standardized uptake value (SUV) cutoff (GTV(2.5)), a fixed threshold of 40% and 50% of the maximum signal intensity (GTV(40%) and GTV(50%)), signal-to-background ratio (SBR)-based adaptive thresholding (GTV(SBR)), gradient find (GTV(GF)), and region growing (GTV(RG)). Overlap analysis was also conducted to assess geographic mismatch between the GTVs delineated using the different techniques. RESULTS: Contours defined using GTV(2.5) failed to provide successful delineation technically in three patients (18% of cases) as SUV(max) < 2.5 and clinically in 14 patients (78% of cases). Overall, the majority of GTVs defined on PET-based techniques were usually smaller than GTV(MRI) (67% of cases). Yet, PET detected frequently tumors that are not visible on MRI and added substantially tumor extension outside the GTV(MRI) in six patients (33% of cases). CONCLUSIONS: The selection of the most appropriate (18)F-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 delineation

Results of Dose-adapted Salvage Radiotherapy After Radical Prostatectomy Based on an Endorectal MRI Target Definition Model

To assess the outcome of patients treated with a dose-adapted salvage radiotherapy (SRT) protocol based on an endorectal magnetic resonance imaging (erMRI) failure definition model after radical prostatectomy (RP)

Impact of ¹⁸F-FDG PET/CT on target volume delineation in recurrent or residual gynaecologic carcinoma

Abstract Background To evaluate the impact of 18F-FDG PET/CT on target volume delineation in gynaecological cancer. Methods F-FDG PET/CT based RT treatment planning was performed in 10 patients with locally recurrent (n = 5) or post-surgical residual gynaecological cancer (n = 5). The gross tumor volume (GTV) was defined by 4 experienced radiation oncologists first using contrast enhanced CT (GTVCT) and secondly using the fused 18F-FDG PET/CT datasets (GTVPET/CT). In addition, the GTV was delineated using the signal-to-background (SBR) ratio-based adaptive thresholding technique (GTVSBR). Overlap analysis were conducted to assess geographic mismatches between the GTVs delineated using the different techniques. Inter- and intra-observer variability were also assessed. Results The mean GTVCT (43.65 cm3) was larger than the mean GTVPET/CT (33.06 cm3), p = 0.02. In 6 patients, GTVPET/CT added substantial tumor extension outside the GTVCT even though 90.4% of the GTVPET/CT was included in the GTVCT and 30.2% of the GTVCT was found outside the GTVPET/CT. The inter- and intra-observer variability was not significantly reduced with the inclusion of 18F-FDG PET imaging (p = 0.23 and p = 0.18, respectively). The GTVSBR was smaller than GTVCT p ≤ 0.005 and GTVPET/CT p ≤ 0.005. Conclusions The use of 18F-FDG PET/CT images for target volume delineation of recurrent or post-surgical residual gynaecological cancer alters the GTV in the majority of patients compared to standard CT-definition. The use of SBR-based auto-delineation showed significantly smaller GTVs. The use of PET/CT based target volume delineation may improve the accuracy of RT treatment planning in gynaecologic cancer.</p

Impact of 18F-FDG PET/CT on target volume delineation in recurrent or residual gynaecologic carcinoma

BACKGROUND: To evaluate the impact of (18)F-FDG PET/CT on target volume delineation in gynaecological cancer. METHODS: F-FDG PET/CT based RT treatment planning was performed in 10 patients with locally recurrent (n = 5) or post-surgical residual gynaecological cancer (n = 5). The gross tumor volume (GTV) was defined by 4 experienced radiation oncologists first using contrast enhanced CT (GTV(CT)) and secondly using the fused (18)F-FDG PET/CT datasets (GTV(PET/CT)). In addition, the GTV was delineated using the signal-to-background (SBR) ratio-based adaptive thresholding technique (GTV(SBR)). Overlap analysis were conducted to assess geographic mismatches between the GTVs delineated using the different techniques. Inter- and intra-observer variability were also assessed. RESULTS: The mean GTV(CT) (43.65 cm(3)) was larger than the mean GTV(PET/CT) (33.06 cm(3)), p = 0.02. In 6 patients, GTV(PET/CT) added substantial tumor extension outside the GTV(CT) even though 90.4% of the GTV(PET/CT) was included in the GTV(CT) and 30.2% of the GTV(CT) was found outside the GTV(PET/CT). The inter- and intra-observer variability was not significantly reduced with the inclusion of (18)F-FDG PET imaging (p = 0.23 and p = 0.18, respectively). The GTV(SBR) was smaller than GTV(CT) p ≤ 0.005 and GTV(PET/CT) p ≤ 0.005. CONCLUSIONS: The use of (18)F-FDG PET/CT images for target volume delineation of recurrent or post-surgical residual gynaecological cancer alters the GTV in the majority of patients compared to standard CT-definition. The use of SBR-based auto-delineation showed significantly smaller GTVs. The use of PET/CT based target volume delineation may improve the accuracy of RT treatment planning in gynaecologic cancer

Outcome and prognostic factors in endometrial stromal tumors: a Rare Cancer Network study

To provide further understanding regarding outcome and prognostic factors of endometrial stromal tumors (EST)

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

PURPOSE: (18)F-Fluorocholine (FCH) and (11)C-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 ≤ 3 ng/ml), curative radiotherapy (RT, 7 patients, PSA ≤ 5 ng/ml) or RP and salvage RT (9 patients, PSA ≤ 5 ng/ml). Both FCH and ACE PET/CT scans were performed in a random sequence a median of 4 days (range 0 to 11 days) apart. FCH PET/CT was started at injection (307 ± 16 MBq) with a 10-min dynamic acquisition of the prostate bed, followed by a whole-body PET scan and late (45 min) imaging of the pelvis. ACE PET/CT was performed as a double whole-body PET scan starting 5 and 22 min after injection (994 ± 72 MBq), and a late view (45 min) 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

Impact of Early Prophylactic Cranial Irradiation With Hippocampal Avoidance on Neurocognitive Function in Patients With Limited Disease Small Cell Lung Cancer. A Multicenter Phase 2 Trial (SAKK 15/12).

PURPOSE To evaluate neurocognitive function (NCF) and clinical outcomes after early hippocampal avoidance (HA) prophylactic cranial irradiation (PCI) in limited disease (LD) small-cell lung cancer (SCLC). METHODS AND MATERIALS In a phase II trial, patients with LD SCLC received HA-PCI concomitant to the 2nd cycle of chemotherapy and thoracic radiotherapy. All patients underwent objective NCF testing at baseline, 6 weeks, 6 and 12 months after HA-PCI. NCF tests included Hopkins Verbal Learning Test Revised, Controlled Oral Word Association, and Trail Making Tests (TMT) A and B. The primary endpoint was NCF decline at 6 months after HA-PCI. We assumed ≤ 30% of patients with no NCF decline as unpromising. Secondary endpoints included brain metastases free survival (BMFS), overall survival (OS), and safety of the concomitant treatment. RESULTS Among the 44 patients enrolled in the trial, 38 had evaluable NCF assessment at 6 months after HA-PCI. The proportion of evaluable patients showing no NCF decline at 6 and 12 months was 34.2% (90% CI: 21.6 - 48.8) and 48.5% (95% CI: 30.8 - 66.5), respectively. Median follow-up was 13.2 months (95% CI: 12.6 - 14.1). At 12 months, BMFS was 84.2%, and OS was 87.7% (95% CI: 73.0 - 94.7). Four patients died due to SCLC, 1 due to respiratory failure, 1 due to hemorrhage, and 1 for unknown reason. The most frequently reported grade ≥ 3 acute adverse events were anemia (21.4%), febrile neutropenia (19.1%) and fatigue (14.3%). CONCLUSIONS The proportion of patients showing no NCF decline 6 and 12 months after early HA-PCI does not appear to be better, but rather similar to that observed in patients receiving sequential PCI without HA. Early HA-PCI in LD SCLC is feasible, with observation of promising BMFS and OS in this selected population