Accuracy of tumor segmentation from multi-parametric prostate MRI and 18F-choline PET/CT for focal prostate cancer therapy applications

Piert, Morand; Shankar, Prasad R.; Montgomery, Jeffrey S.; Kunju, Lakshmi P.; Rogers, Virginia; Siddiqui, Javed; Rajendiran, Thekkelnaycke M.; Hearn, Jason W.D.; George, Arvin; Shao, Xia; Davenport, Matthew S.

doi:10.1186/s13550-018-0377-5

Cited by 25 publications

(22 citation statements)

References 46 publications

(55 reference statements)

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“…In the absence of better techniques to place ablation zones more accurately, our data suggest that the 5 mm margins used for this procedure were insufficient and should be extended 3 mm further for complete ablation of the dominant lesion in all cases. This recommendation is consistent with other reports which suggest using margins of at least 9 mm although they are based on segmentation variability and MR visibility of tumors. Increasing margins may not be possible if the tumor is close to a functional structure that needs to be preserved, such as the urethra or rectum, but Fig.…”

Section: Discussionsupporting

confidence: 92%

“…However, a future study can focus on the impact of tumor segmentation variability on analysis of coverage of the tumor by the ablation zone. Furthermore, some studies suggest tumor boundaries extend beyond what can be seen on MRI which means our results likely underestimate the volume of the untreated tumor. Histological analysis, which was not performed in this study, would reveal the full extent of untreated tumor.…”

Section: Discussionmentioning

confidence: 85%

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Evaluation of tumor coverage after MR‐guided prostate focal laser ablation therapy

et al. 2018

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Purpose Prostate cancer is the most common noncutaneous cancer among men in the USA. Focal laser thermal ablation (FLA) has the potential to control small tumors while preserving urinary and erectile function by leaving the neurovascular bundles and urethral sphincters intact. Accurate needle guidance is critical to the success of FLA. Multiparametric magnetic resonance images (mpMRI) can be used to identify targets, guide needles, and assess treatment outcomes. In this study, we evaluated the location of ablation zones relative to targeted lesions in 23 patients who underwent FLA therapy in a phase II trial. The ablation zone margins and unablated tumor volume were measured to determine whether complete coverage of each tumor was achieved, which would be considered a clinically successful ablation. Methods Preoperative mpMRI was acquired for each patient 2–3 months preceding the procedure and the prostate and lesion(s) were manually contoured on 3 T T2‐weighted axial images. The prostate and ablation zone(s) were also manually contoured on postablation 1.5 T T1‐weighted contrast‐enhanced axial images acquired immediately after the procedure intraoperatively. The lesion surface was nonrigidly registered to the postablation image using an initial affine registration followed by nonrigid thin‐plate spline registration of the prostate surfaces. The margins between the registered lesion and ablation zone were calculated using a uniform spherical distribution of rays, and the volume of intersection was also calculated. Each prostate was contoured five times to determine the segmentation variability and its effect on intersection of the lesion and ablation zone. Results Our study showed that the boundaries of the segmented tumor and ablation zone were close. Of the 23 lesions that were analyzed, 11 were completely covered by the ablation zone and 12 were partially covered. A shift of 1.0, 2.0, and 2.6 mm would result in 19, 21, and all tumors completely covered by the ablation zone, respectively. The median unablated tumor volume across all tumors was 0.1 mm3 with an IQR of 3.7 mm3, which was 0.2% of the median tumor volume (46.5 mm3 with an IQR of 46.3 mm3). The median extension of the tumors beyond the ablation zone, in cases which were partially ablated, was 0.9 mm (IQR of 1.3 mm), with the furthest tumor extending 2.6 mm. Conclusion In all cases, the boundary of the tumor was close to the boundary of the ablation zone, and in some cases, the boundary of the ablation zone did not completely enclose the tumor. Our results suggest that some of the ablations were not clinically successful and that there is a need for more accurate needle tracking and guidance methods. Limitations of the study include errors in the registration and segmentation methods used as well as different voxel sizes and contrast between the registered T2 and T1 MRI sequences and asymmetric swelling of the prostate postprocedurally.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 85%

Evaluation of tumor coverage after MR‐guided prostate focal laser ablation therapy

et al. 2018

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“…Results are shown in Tables 1–5. Table 1 lists the 18 studies and shows the accuracy calculation 19,23–39 . This determined the order of the studies as presented in the remaining Tables 2–5.…”

Section: Resultsmentioning

confidence: 99%

How accurately can multiparametric magnetic resonance imaging measure the tumour volume of a prostate cancer? Results of a systematic review

Christie

Sharpley

2020

J Med Imag Rad Onc

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Summary The tumour volume of a cancer within the prostate gland is commonly measured with multiparametric MRI. The measurement has a role in many clinical scenarios including focal therapy, but the accuracy of it has never been systematically reviewed. We included articles if they compared tumour volume measurements obtained by mpMRI with a reference volume measurement obtained after radical prostatectomy. Correlation and concordance statistics were summarised. A simple accuracy score was derived by dividing the given mean or median mpMRI volume by the histopathological reference volume. Factors affecting the accuracy were noted. Scores for potential bias and quality were calculated for each article. A total of 18 articles describing 1438 patients were identified. Nine articles gave Pearson’s correlation scores, with a median value of 0.75 but the range was wide (0.42–0.97). A total of 11 articles reported mean values for volume while 9 reported median values. For all 18 articles, the mean or median values for MRI volumes were lower than the corresponding reference values suggesting consistent underestimation. For articles reporting mean and median values for volume, the median accuracy scores were 0.83 and 0.80, respectively. The accuracy was higher for tumours of greater volume, higher grade and when an endorectal coil was used. Accuracy did not seem to improve over time, with a 3 Tesla magnet or by applying a shrinkage factor to the reference measurement. Most studies showed evidence of at least moderate bias, and their quality was highly variable, but neither of these appeared to affect accuracy.

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“…Prostate and tumor volumes are consistently underrepresented with mpMRI. 38,39 Placement of a TRUS device can cause significant gland deformation that increases the error in lesion sampling,…”

Section: Limitations Of Mpmri and Mr-trus Fusion Biopsymentioning

confidence: 99%

Current Status of MRI and PET in the NCCN Guidelines for Prostate Cancer

Mason

Eastham

Davis³

et al. 2019

Journal of the National Comprehensive Cancer Network

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Prostate cancer (PCa) represents a significant source of morbidity and mortality for men in the United States, with approximately 1 in 9 being diagnosed with PCa in their lifetime. The role of imaging in the evaluation of men with PCa has evolved and currently plays a central role in diagnosis, treatment planning, and evaluation of recurrence. Appropriate use of multiparametric MRI (mpMRI) and MRI-guided transrectal ultrasound (MR-TRUS) biopsy increases the detection of clinically significant PCa while decreasing the detection of clinically insignificant PCa. This process may help patients with clinically insignificant PCa avoid the adverse effects of unnecessary therapy. In the setting of a known PCa, patients with low-grade disease can be observed using active surveillance, which often includes a combination of prostate-specific antigen (PSA) testing, serial mpMRI, and, if indicated, follow-up systematic and targeted TRUS-guided tissue sampling. mpMRI can provide important information in the posttreatment setting, but PET/CT is creating a paradigm shift in imaging standards for patients with locally recurrent and metastatic PCa. This article examines the strengths and limitations of mpMRI for initial PCa diagnosis, active surveillance, recurrent disease evaluation, and image-guided biopsies, and the use of PET/CT imaging in men with recurrent PCa. The goal of this review is to provide a rational basis for current NCCN Clinical Practice Guidelines in Oncology for PCa as they pertain to the use of these advanced imaging modalities.

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Accuracy of tumor segmentation from multi-parametric prostate MRI and 18F-choline PET/CT for focal prostate cancer therapy applications

Cited by 25 publications

References 46 publications

Evaluation of tumor coverage after MR‐guided prostate focal laser ablation therapy

Evaluation of tumor coverage after MR‐guided prostate focal laser ablation therapy

How accurately can multiparametric magnetic resonance imaging measure the tumour volume of a prostate cancer? Results of a systematic review

Current Status of MRI and PET in the NCCN Guidelines for Prostate Cancer

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