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Comparison of prostate delineation on multimodality imaging for MR-guided radiotherapy.

ABSTRACT: OBJECTIVE::With increasing incorporation of MRI in radiotherapy, we investigate two MRI sequences for prostate delineation in radiographer-led image guidance. METHODS::Five therapeutic radiographers contoured the prostate individually on CT, T2 weighted (T2W) and T2* weighted (T2*W) imaging for 10 patients. Contours were analysed with Monaco ADMIRE (research v. 2.0) to assess interobserver variability and accuracy by comparison with a gold standard clinician contour. Observers recorded time taken for contouring and scored image quality and confidence in contouring. RESULTS::There is good agreement when comparing radiographer contours to the gold-standard for all three imaging types with Dice similarity co-efficient 0.91-0.94, Cohen's ? 0.85-0.91, Hausdorff distance 4.6-7.6?mm and mean distance between contours 0.9-1.2?mm. In addition, there is good concordance between radiographers across all imaging modalities. Both T2W and T2*W MRI show reduced interobserver variability and improved accuracy compared to CT, this was statistically significant for T2*W imaging compared to CT across all four comparison metrics. Comparing MRI sequences reveals significantly reduced interobserver variability and significantly improved accuracy on T2*W compared to T2W MRI for DSC and Cohen's ?. Both MRI sequences scored significantly higher compared to CT for image quality and confidence in contouring, particularly T2*W. This was also reflected in the shorter time for contouring, measuring 15.4, 9.6 and 9.8?min for CT, T2W and T2*W MRI respectively. Conclusion: Therapeutic radiographer prostate contours are more accurate, show less interobserver variability and are more confidently and quickly outlined on MRI compared to CT, particularly using T2*W MRI. Advances in knowledge: Our work is relevant for MRI sequence choice and development of the roles of the interprofessional team in the advancement of MRI-guided radiotherapy.

SUBMITTER: Pathmanathan AU

PROVIDER: S-EPMC6540870 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Comparison of prostate delineation on multimodality imaging for MR-guided radiotherapy.

Pathmanathan Angela U AU McNair Helen A HA Schmidt Maria A MA Brand Douglas H DH Delacroix Louise L Eccles Cynthia L CL Gordon Alexandra A Herbert Trina T van As Nicholas J NJ Huddart Robert A RA Tree Alison C AC

The British journal of radiology 20190124 1095

<h4>Objective:</h4>With increasing incorporation of MRI in radiotherapy, we investigate two MRI sequences for prostate delineation in radiographer-led image guidance.<h4>Methods:</h4>Five therapeutic radiographers contoured the prostate individually on CT, T<sub>2</sub> weighted (T<sub>2</sub>W) and T<sub>2</sub>* weighted (T<sub>2</sub>*W) imaging for 10 patients. Contours were analysed with Monaco ADMIRE (research v. 2.0) to assess interobserver variability and accuracy by comparison with a go ...[more]

PMID: 30676772

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Project description:Multi-modality image-guided radiotherapy is the standard of care in contemporary cancer management; however, it is not common in preclinical settings due to both hardware and software limitations. Soft tissue lesions, such as orthotopic prostate tumors, are difficult to identify using cone beam computed tomography (CBCT) imaging alone. In this study, we characterized a research magnetic resonance (MR) scanner for preclinical studies and created a protocol for combined MR-CBCT image-guided small animal radiotherapy. Two in-house dual-modality, MR and CBCT compatible, phantoms were designed and manufactured using 3D printing technology. The phantoms were used for quality assurance tests and to facilitate end-to-end testing for combined preclinical MR and CBCT based treatment planning. MR and CBCT images of the phantoms were acquired utilizing a Varian 4.7 T scanner and XRad-225Cx irradiator, respectively. The geometry distortion was assessed by comparing MR images to phantom blueprints and CBCT. The corrected MR scans were co-registered with CBCT and subsequently used for treatment planning. The fidelity of 3D printed phantoms compared to the blueprint design yielded favorable agreement as verified with the CBCT measurements. The geometric distortion, which varied between -5% and 11% throughout the scanning volume, was substantially reduced to within 0.4% after correction. The distortion free MR images were co-registered with the corresponding CBCT images and imported into a commercial treatment planning software SmART Plan. The planning target volume (PTV) was on average 19% smaller when contoured on the corrected MR-CBCT images relative to raw images without distortion correction. An MR-CBCT based preclinical workflow was successfully designed and implemented for small animal radiotherapy. Combined MR-CBCT image-guided radiotherapy for preclinical research potentially delivers enhanced relevance to human radiotherapy for various disease sites. This novel protocol is wide-ranging and not limited to the orthotopic prostate tumor study presented in the study.

Project description:ImportanceTargeted magnetic resonance (MR)/ultrasound fusion prostate biopsy has been shown to detect prostate cancer. The implications of targeted biopsy alone vs standard extended-sextant biopsy or the 2 modalities combined are not well understood.ObjectiveTo assess targeted vs standard biopsy and the 2 approaches combined for the diagnosis of intermediate- to high-risk prostate cancer.Design, setting, and participantsProspective cohort study of 1003 men undergoing both targeted and standard biopsy concurrently from 2007 through 2014 at the National Cancer Institute in the United States. Patients were referred for elevated level of prostate-specific antigen (PSA) or abnormal digital rectal examination results, often with prior negative biopsy results. Risk categorization was compared among targeted and standard biopsy and, when available, whole-gland pathology after prostatectomy as the "gold standard."InterventionsPatients underwent multiparametric prostate magnetic resonance imaging to identify regions of prostate cancer suspicion followed by targeted MR/ultrasound fusion biopsy and concurrent standard biopsy.Main outcomes and measuresThe primary objective was to compare targeted and standard biopsy approaches for detection of high-risk prostate cancer (Gleason score ≥ 4 + 3); secondary end points focused on detection of low-risk prostate cancer (Gleason score 3 + 3 or low-volume 3 + 4) and the biopsy ability to predict whole-gland pathology at prostatectomy.ResultsTargeted MR/ultrasound fusion biopsy diagnosed 461 prostate cancer cases, and standard biopsy diagnosed 469 cases. There was exact agreement between targeted and standard biopsy in 690 men (69%) undergoing biopsy. Targeted biopsy diagnosed 30% more high-risk cancers vs standard biopsy (173 vs 122 cases, P < .001) and 17% fewer low-risk cancers (213 vs 258 cases, P < .001). When standard biopsy cores were combined with the targeted approach, an additional 103 cases (22%) of mostly low-risk prostate cancer were diagnosed (83% low risk, 12% intermediate risk, and 5% high risk). The predictive ability of targeted biopsy for differentiating low-risk from intermediate- and high-risk disease in 170 men with whole-gland pathology after prostatectomy was greater than that of standard biopsy or the 2 approaches combined (area under the curve, 0.73, 0.59, and 0.67, respectively; P < .05 for all comparisons).Conclusions and relevanceAmong men undergoing biopsy for suspected prostate cancer, targeted MR/ultrasound fusion biopsy, compared with standard extended-sextant ultrasound-guided biopsy, was associated with increased detection of high-risk prostate cancer and decreased detection of low-risk prostate cancer. Future studies will be needed to assess the ultimate clinical implications of targeted biopsy.Trial registrationclinicaltrials.gov Identifier: NCT00102544.

Dataset Information

Comparison of prostate delineation on multimodality imaging for MR-guided radiotherapy.

Publications

Comparison of prostate delineation on multimodality imaging for MR-guided radiotherapy.

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