Τίτλος:
Evaluation of patient-specific MR distortion correction schemes for improved target localization accuracy in SRS
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Purpose: This work aims at promoting target localization accuracy in cranial stereotactic radiosurgery (SRS) applications by focusing on the correction of sequence-dependent (also patient induced) magnetic resonance (MR) distortions at the lesion locations. A phantom-based quality assurance (QA) methodology was developed and implemented for the evaluation of three distortion correction techniques. The same approach was also adapted to cranial MR images used for SRS treatment planning purposes in single or multiple brain metastases cases. Methods: A three-dimensional (3D)-printed head phantom was filled with a 3D polymer gel dosimeter. Following treatment planning and dose delivery, volumes of radiation-induced polymerization served as hypothetical lesions, offering adequate MR contrast with respect to the surrounding unirradiated areas. T1-weighted (T1w) MR imaging was performed at 1.5 T using the clinical scanning protocol for SRS. Additional images were acquired to implement three distortion correction methods; the field mapping (FM), mean image (MI) and signal integration (SI) techniques. Reference lesion locations were calculated as the averaged centroid positions of each target identified in the forward and reverse read gradient polarity MRI scans. The same techniques and workflows were implemented for the correction of contrast-enhanced T1w MR images of 10 patients with a total of 27 brain metastases. Results: All methods employed in the phantom study diminished spatial distortion. Median and maximum distortion magnitude decreased from 0.7 mm (2.10 ppm) and 0.8 mm (2.36 ppm), respectively, to <0.2 mm (0.61 ppm) at all target locations, using any of the three techniques. Image quality of the corrected images was acceptable, while contrast-to-noise ratio slightly increased. Results of the patient study were in accordance with the findings of the phantom study. Residual distortion in corrected patient images was found to be <0.3 mm in the vast majority of targets. Overall, the MI approach appears to be the most efficient correction method from the three investigated. Conclusions: In cranial SRS applications, patient-specific distortion correction at the target location(s) is feasible and effective, despite the expense of longer imaging time since additional MRI scan(s) need to be performed. A phantom-based QA methodology was developed and presented to reassure efficient implementation of correction techniques for sequence-dependent spatial distortion. © 2020 American Association of Physicists in Medicine
Συγγραφείς:
Dellios, D.
Pappas, E.P.
Seimenis, I.
Paraskevopoulou, C.
Lampropoulos, K.I.
Lymperopoulou, G.
Karaiskos, P.
Περιοδικό:
Medical Physics
Εκδότης:
John Wiley and Sons Ltd
Λέξεις-κλειδιά:
3D printers; Computerized tomography; Filled polymers; Location; Magnetic resonance; Magnetic resonance imaging; Pathology; Phantoms; Quality assurance; Quality control, Contrast to noise ratio; Efficient implementation; Multiple brain metastasis; Polymer gel dosimeter; Radiation-induced polymerization; Reverse read gradients; Stereotactic radiosurgery; Threedimensional (3-d), Image enhancement, gadolinium pentetate; nuclear magnetic resonance imaging agent; polymer, Article; brain metastasis; cancer localization; clinical article; contrast enhancement; contrast to noise ratio; controlled study; data analysis software; digital imaging and communications in medicine; human; image analysis; image processing; image quality; magnetic field; nuclear magnetic resonance; polymerization; quality control; radiation dose; signal noise ratio; stereotactic radiosurgery; three dimensional printing; three-dimensional imaging; treatment planning; brain tumor; diagnostic imaging; imaging phantom; nuclear magnetic resonance imaging; nuclear magnetic resonance spectroscopy; radiosurgery, Brain Neoplasms; Humans; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Phantoms, Imaging; Radiosurgery
