Prospective feasibility analysis of a novel off-line approach for MR-guided radiotherapy

Bostel, Tilman; Pfaffenberger, A.; Delorme, Stefan; Dreher, Constantin; Echner, G.; Haering, P.; Lang, Clemens; Splinter, M.; Laun, Frederik Bernd; Müller, Marco; Jäkel, Oliver; Debus, Jürgen; Huber, Peter E.; Sterzing, Florian; Nicolay, Nils H.

doi:10.1007/s00066-017-1258-y

Cited by 18 publications

(23 citation statements)

References 34 publications

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“…Magnetic resonance (MR) imaging, with its superior soft-tissue contrast, facilitates enhanced differentiation between cancerous and healthy tissue as well as functional assessment of treatment response [ 5 , 6 ]. Given the technical challenges in integrating MR imaging (MRI) into a linear accelerator, first studies on MR-guided radiotherapy (MRgRT) focused on offline solutions and reported efficacy and feasibility for this technique [ 7 – 10 ].…”

Section: Introductionmentioning

confidence: 99%

First prospective clinical evaluation of feasibility and patient acceptance of magnetic resonance-guided radiotherapy in Germany

et al. 2020

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Purpose Magnetic resonance-guided radiotherapy (MRgRT) has recently been introduced in our institution. As MRgRT requires high patient compliance compared to conventional techniques and can be associated with prolonged treatment times, feasibility and patient tolerance were prospectively assessed using patient-reported outcome questionnaires (PRO-Q). Materials and methods Forty-three patients were enrolled in a prospective observational study and treated with MRgRT on a low-field hybrid Magnetic Resonance Linear Accelerator system (MR-Linac) between April 2018 and April 2019. For assistance in gated breath-hold delivery using cine-MRI, a video feedback system was installed. PRO-Qs consisted of questions on MR-related complaints and also assessed aspects of active patient participation. Results The most commonly treated anatomic sites were nodal metastases and liver lesions. The mean treatment time was 34 min with a mean beam-on time of 2:17 min. Gated stereotactic body radiotherapy (SBRT) was applied in 47% of all patients. Overall, patients scored MRgRT as positive or at least tolerable in the PRO-Q. Almost two thirds of patients (65%) complained about at least one item of the PRO-Q (score ≥4), mainly concerning coldness, paresthesia, and uncomfortable positioning. All patients reported high levels of satisfaction with their active role using the video feedback system in breath-hold delivery. Conclusion MRgRT was successfully implemented in our clinic and well tolerated by all patients, despite MR-related complaints and complaints about uncomfortable immobilization. Prospective clinical studies are in development for further evaluation of MRgRT and for quantification of the benefit of MR-guided on-table adaptive radiotherapy.

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Section: Introductionmentioning

confidence: 99%

First prospective clinical evaluation of feasibility and patient acceptance of magnetic resonance-guided radiotherapy in Germany

et al. 2020

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“…Dosimetric deviations in prostate radiotherapy resulting from intra- and interfractional anatomic variability have been incompletely understood, and an in-depth comprehension about the dosimetric impact of position verification imaging becomes more important as individual fraction dose are increasing for hypofractionated or even stereotactic treatment approaches ( 18 , 19 , 30 ). Previous analyses have generally been limited by the insufficient quality or frequency of position verification imaging and the lacking availability of elastic image registration tools.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

et al. 2020

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Background To investigate deviations between planned and applied treatment doses for hypofractionated prostate radiotherapy and to quantify dosimetric accuracy in dependence of the image guidance frequency. Methods Daily diagnostic in-room CTs were carried out in 10 patients in treatment position as image guidance for hypofractionated prostate radiotherapy. Fraction doses were mapped to the planning CTs and recalculated, and applied doses were accumulated voxel-wise using deformable registration. Non-daily imaging schedules were simulated by deriving position correction vectors from individual scans and used to rigidly register the following scans until the next repositioning before dose recalculation and accumulation. Planned and applied doses were compared regarding dose-volume indices and TCP and NTCP values in dependence of the imaging and repositioning frequency. Results Daily image-guided repositioning was associated with only negligible deviations of analyzed dose-volume parameters and conformity/homogeneity indices for the prostate, bladder and rectum. Average CTV T did not significantly deviate from the plan values, and rectum NTCPs were highly comparable, while bladder NTCPs were reduced. For non-daily image-guided repositioning, there were significant deviations in the high-dose range from the planned values. Similarly, CTV dose conformity and homogeneity were reduced. While TCPs and rectal NTCPs did not significantly deteriorate for non-daily repositioning, bladder NTCPs appeared falsely diminished in dependence of the imaging frequency. Conclusion Using voxel-by-voxel dose accumulation, we showed for the first time that daily image-guided repositioning resulted in only negligible dosimetric deviations for hypofractionated prostate radiotherapy. Regarding dosimetric aberrations for non-daily imaging, daily imaging is required to adequately deliver treatment.

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“…Our manuscript analyzed data from a prospective trial investigating daily MRI in treatment position as a means of off-line MR-guided radiotherapy [19,20]. In this study, 8 patients with locally advanced rectal adenocarcinoma were enrolled between October 2013 and June 2017.…”

Section: Patientsmentioning

confidence: 99%

“…All patients received daily short MR scans in treatment position prior to irradiation with the same immobilization equipment used for RT to image the morphological and functional changes of the tumorous tissue during the treatment. The transfer of patients between the MR device and the linear accelerator was realized with a shuttle system (Zephyr system, Diacor, Salt Lake City, USA) [19].…”

Section: Patient Immobilization and Treatment Planningmentioning

confidence: 99%

Exploring MR regression patterns in rectal cancer during neoadjuvant radiochemotherapy with daily T2- and diffusion-weighted MRI

et al. 2020

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Background: To date, only limited magnetic resonance imaging (MRI) data are available concerning tumor regression during neoadjuvant radiochemotherapy (RCT) of rectal cancer patients, which is a prerequisite for adaptive radiotherapy (RT) concepts. This exploratory study prospectively evaluated daily fractional MRI during neoadjuvant treatment to analyze the predictive value of MR biomarkers for treatment response. Methods: Locally advanced rectal cancer patients were examined with daily MRI during neoadjuvant RCT. Contouring of the tumor volume was performed for each MRI scan by using T2-and diffusion-weighted-imaging (DWI)-sequences. The daily apparent-diffusion coefficient (ADC) was calculated. Volumetric and functional tumor changes during RCT were analyzed and correlated with the pathological response after surgical resection. Results: In total, 171 MRI scans of eight patients were analyzed regarding anatomical and functional dynamics during RCT. Pathological complete response (pCR) could be achieved in four patients, and four patients had a pathological partial response (pPR) following neoadjuvant treatment. T2-and DWI-based volumetry proved to be statistically significant in terms of therapeutic response, and volumetric thresholds at week two and week four during RCT were defined for the prediction of pCR. In contrast, the average tumor ADC values widely overlapped between both response groups during RCT and appeared inadequate to predict treatment response in our patient cohort. Conclusion: This prospective exploratory study supports the hypothesis that MRI may be able to predict pCR of rectal cancers early during neoadjuvant RCT. Our data therefore provide a useful template to tailor future MRguided adaptive treatment concepts.

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Prospective feasibility analysis of a novel off-line approach for MR-guided radiotherapy

Abstract: This trial demonstrated for the first time the feasibility and patient compliance of a shuttle-based off-line approach to MRgRT of pelvic malignancies.

Cited by 18 publications

References 34 publications

First prospective clinical evaluation of feasibility and patient acceptance of magnetic resonance-guided radiotherapy in Germany

First prospective clinical evaluation of feasibility and patient acceptance of magnetic resonance-guided radiotherapy in Germany

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

Exploring MR regression patterns in rectal cancer during neoadjuvant radiochemotherapy with daily T2- and diffusion-weighted MRI

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