Feasibility of biology-guided radiotherapy using PSMA-PET to boost to dominant intraprostatic tumour

Gaudreault, Mathieu; Chang, David; Hardcastle, Nicholas; Jackson, Price; Kron, Tomas; Hofman, Michael S

doi:10.1016/j.ctro.2022.05.005

Cited by 5 publications

(5 citation statements)

References 51 publications

(48 reference statements)

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“…Tsui et al evaluated the impact of an automatically generated DIL, leading to the conclusion that dosimetry planning was significantly impacted by the accuracy of the DIL delineation [27]. Finally, other imaging modalities, such as PSMA-positron emission tomography (PET), could be used to segment the DIL [28]. The impact of the choice of window levelling should be studied [29].…”

Section: Discussionmentioning

confidence: 99%

Inter-Rater Variability of Prostate Lesion Segmentation on Multiparametric Prostate MRI

Jeganathan,

Salgues,

Schick

et al. 2023

Biomedicines

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Introduction: External radiotherapy is a major treatment for localized prostate cancer (PCa). Dose escalation to the whole prostate gland increases biochemical relapse-free survival but also acute and late toxicities. Dose escalation to the dominant index lesion (DIL) only is of growing interest. It requires a robust delineation of the DIL. In this context, we aimed to evaluate the inter-observer variability of DIL delineation. Material and Methods: Two junior radiologists and a senior radiation oncologist delineated DILs on 64 mpMRIs of patients with histologically confirmed PCa. For each mpMRI and each reader, eight individual DIL segmentations were delineated. These delineations were blindly performed from one another and resulted from the individual analysis of the T2, apparent diffusion coefficient (ADC), b2000, and dynamic contrast enhanced (DCE) sequences, as well as the analysis of combined sequences (T2ADC, T2ADCb2000, T2ADCDCE, and T2ADCb2000DCE). Delineation variability was assessed using the DICE coefficient, Jaccard index, Hausdorff distance measure, and mean distance to agreement. Results: T2, ADC, T2ADC, b2000, T2 + ADC + b2000, T2 + ADC + DCE, and T2 + ADC + b2000 + DCE sequences obtained DICE coefficients of 0.51, 0.50, 0.54, 0.52, 0.54, 0.55, 0.53, respectively, which are significantly higher than the perfusion sequence alone (0.35, p < 0.001). The analysis of other similarity metrics lead to similar results. The tumor volume and PI-RADS classification were positively correlated with the DICE scores. Conclusion: Our study showed that the contours of prostatic lesions were more reproducible on certain sequences but confirmed the great variability of prostatic contours with a maximum DICE coefficient calculated at 0.55 (joint analysis of T2, ADC, and perfusion sequences).

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Section: Discussionmentioning

confidence: 99%

Inter-Rater Variability of Prostate Lesion Segmentation on Multiparametric Prostate MRI

Jeganathan,

Salgues,

Schick

et al. 2023

Biomedicines

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“…We chose to use MRI-based fusion and re-optimization in this study because the majority of modern data assessing DILs have used MRI, and MRIs are the most frequent advanced imaging modality available in our patient population. In recent years, there has been an increasing utilization of nuclear imaging, including PSMA-PET and fluciclovine F-18 PET in the initial diagnostic workup of prostate cancer, and these modalities are also being used to define DILs [29][30][31]. As nuclear imaging becomes increasingly available in our patient population, we hope to explore and implement similar image guidance and dose differentiation techniques using these imaging modalities.…”

Section: Discussionmentioning

confidence: 99%

Dose differentiated high-dose-rate prostate brachytherapy: a feasibility assessment of MRI-guided dose escalation to dominant intra-prostatic lesions

Luminais¹,

Nourzadeh²,

Aliotta³

et al. 2022

jcb

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Purpose: Prostate brachytherapy is routinely performed with trans-rectal ultrasound (TRUS)-or computed tomography (CT)-based planning that cannot delineate dominant intra-prostatic lesions (DILs). In contrast, magnetic resonance imaging (MRI)-based planning allows for more accurate DIL delineation and dose escalation. This study assessed the maximum achievable dose escalation to DILs.Material and methods: We retrospectively identified 24 patients treated with high-dose-rate (HDR) prostate brachytherapy boost (15 Gy in 1 fraction). All patients had a pre-treatment prostate MRI with 1-3 DILs. MRIs were used to delineate DILs and were co-registered to TRUS intra-procedure. Treatment plans were experimentally re-optimized to escalate DIL dose. Dosimetric indices from the original and re-optimized plans were compared using two-tailed paired t-test. Re-optimized plans were deemed acceptable if they achieved all of the following criteria: prostate D 90 > 100%, prostate V 100 > 90%, urethra D 10 < 118%, rectum V 80 < 0.5 cc, bladder D 1cc < 75%, or if they did not exceed organs at risk (OARs) doses of the original plan.Results: The mean DIL D 90 was significantly increased from 134% of the prescription dose on the original plans to 154% on the re-optimized plans. The mean urethra D 10 and mean bladder D 1cc were significantly reduced from 123% to 117% and from 72% to 65%, respectively. Prostate D 90 was reduced from 106% to 102%, and prostate V 100 was reduced from 93% to 91%.Conclusions: We re-optimized HDR brachytherapy plans to escalate DILs dose to a mean D 90 of > 150% while maintaining favorable prostate coverage and OARs doses. We propose DIL D 90 dose of > 150% (22.5 Gy) as an achievable goal.

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“…Therefore, the PET signal coming from this volume must originate from the tumour only and not from any physiological uptake in the surrounding tissue or another tumour. The PET distribution surrounding the tumour was characterised as a function of the distance from the GTV by generating consecutive 3 mm outer margin expansion of the GTV, all disjoint from each other ( 14 , 15 ). The expansion was performed for distances = [3 mm, 50 mm] and SUVmax inside these shells was reported.…”

Section: Methodsmentioning

confidence: 99%

Combined biology-guided radiotherapy and Lutetium PSMA theranostics treatment in metastatic castrate-resistant prostate cancer

Gaudreault

Chang²,

Hardcastle³

et al. 2023

Front. Oncol.

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BackgroundLutetium-177 [177Lu]-PSMA-617 is a targeted radioligand that binds to prostate-specific membrane antigen (PSMA) and delivers radiation to metastatic prostate cancer. The presence of PSMA-negative/FDG-positive metastases can preclude patients from being eligible for this treatment. Biology-guided radiotherapy (BgRT) is a treatment modality that utilises tumour PET emissions to guide external beam radiotherapy. The feasibility of combining BgRT and Lutetium-177 [177Lu]-PSMA-617 for patients with PSMA-negative/FDG-positive metastatic prostate cancer was explored.Materials and methodsAll patients excluded from the LuPSMA clinical trial (ID: ANZCTR12615000912583) due to PSMA/FDG discordance were retrospectively reviewed. A hypothetical workflow where PSMA-negative/FDG-positive metastases would be treated with BgRT whilst PSMA-positive metastases would be treated with Lutetium-177 [177Lu]-PSMA-617 was considered. Gross tumour volume (GTV) of PSMA-negative/FDG-positive tumours were delineated on the CT component of the FDG PET/CT scan. Tumours were deemed suitable for BgRT if (1) normalised SUV (nSUV), defined as the ratio of maximum SUV (SUVmax) inside the GTV to mean SUV inside a 5 mm/10 mm/20 mm margin expansion of the GTV, was larger than a pre-specified nSUV threshold and (2) there was no PET avidity inside the margin expansion.ResultsIn 75 patients screened for Lutetium-177 [177Lu]-PSMA-617 treatment, 6 patients were excluded due to PSMA/FDG discordance and 89 PSMA-negative/FDG-positive targets were identified. GTV volumes ranged from 0.3 cm3 to 186 cm3 (median GTV volume = 4.3 cm3, IQR = 2.2 cm3 – 7.4 cm3). SUVmax inside GTVs ranged between 3 and 12 (median SUVmax = 4.8, IQR = 3.9 – 6.2). With nSUV ≥ 3, 67%/54%/39% of all GTVs were suitable for BgRT within 5 mm/10 mm/20 mm from the tumour. Bone and lung metastases were the best candidates for BgRT (40%/27% of all tumours suitable for BgRT with nSUV ≥ 3 within 5 mm from the GTV were bone/lung GTVs).ConclusionsCombined BgRT/Lutetium-177 [177Lu]-PSMA-617 therapy is feasible for patients with PSMA/FDG discordant metastases.

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Feasibility of biology-guided radiotherapy using PSMA-PET to boost to dominant intraprostatic tumour

Cited by 5 publications

References 51 publications

Inter-Rater Variability of Prostate Lesion Segmentation on Multiparametric Prostate MRI

Inter-Rater Variability of Prostate Lesion Segmentation on Multiparametric Prostate MRI

Dose differentiated high-dose-rate prostate brachytherapy: a feasibility assessment of MRI-guided dose escalation to dominant intra-prostatic lesions

Combined biology-guided radiotherapy and Lutetium PSMA theranostics treatment in metastatic castrate-resistant prostate cancer

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