Add like
Add dislike
Add to saved papers

Evaluation of Tumour Coverage after MR-Guided Prostate Focal Laser Ablation Therapy.

Medical Physics 2018 November 18
PURPOSE: Prostate cancer is the most common non-cutaneous cancer among men in the USA.[1] Focal laser thermal ablation (FLA) has the potential to control small tumours 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. Multi-parametric 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 tumour volume were measured to determine whether complete coverage of each tumour was achieved, which would be considered a clinically successful ablation.

METHODS: Pre-operative mpMRI were acquired for each patient two to three months preceding the procedure and the prostate and lesion(s) were manually contoured on 3T T2-weighted axial images. The prostate and ablation zone(s) were also manually contoured on post-ablation 1.5T T1-weighted contrast-enhanced axial images acquired immediately after the procedure intra-operatively. The lesion surface was non-rigidly regis-tered to the post-ablation image using an initial affine registration followed by non-rigid 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 inter-section 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 tu-mour and ablation zone were close. Of the 23 lesions that were analyzed, eleven were completely covered by the ablation zone and twelve were par-tially covered. A shift of 1.0, 2.0, and 2.6 mm would result in 19, 21, and all tumours completely covered by the ablation zone, respectively. The median unablated tumour volume across all tumours was 0.1 mm3 with an IQR of 3.7 mm3 , which was 0.2% of the median tumour volume (46.5 mm3 with an IQR of 46.3 mm3 ). The median extension of the tumours beyond the ablation zone, in cases which were partially ablated, was 0.9 mm (IQR of 1.3 mm), with the furthest tumour extending 2.6 mm.

CONCLUSION: In all cases the boundary of the tumour was close to the boundary of the ablation zone and in some cases the boundary of the ablation zone did not completely enclose the tumour. 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 segmenta-tion methods used, as well as different voxel sizes and contrast between the registered T2 and T1 MRI sequences and asymmetric swelling of the prostate post-procedurally. This article is protected by copyright. All rights reserved.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app