Dynamic keyhole: A novel method to improve MR images in the presence of respiratory motion for real‐time MRI

Purpose: In this work, the authors present a novel magnetic resonance imaging reconstruction method to improve the quality of MR images in the presence of respiratory motion for real‐time thoracic image‐guided radiotherapy. Methods: This new reconstruction method is called dynamic keyhole and utiliz...

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Veröffentlicht in:Medical physics (Lancaster) Jg. 41; H. 7; S. 072304 - n/a
Hauptverfasser: Lee, Danny, Pollock, Sean, Whelan, Brendan, Keall, Paul, Kim, Taeho
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States American Association of Physicists in Medicine 01.07.2014
Schlagworte:
60 APPLIED LIFE SCIENCES
Biological material, e.g. blood, urine; Haemocytometers
biomedical MRI
Clinical applications
DATASETS
Digital computing or data processing equipment or methods, specially adapted for specific applications
Digital image processing
Humans
image coding
Image coding, e.g. from bit‐mapped to non bit‐mapped
Image data processing or generation, in general
IMAGE PROCESSING
Image Processing, Computer-Assisted - methods
image reconstruction
image resolution
Involving electronic [emr] or nuclear [nmr] magnetic resonance, e.g. magnetic resonance imaging
Magnetic Resonance Imaging - methods
Medical image artifacts
Medical image contrast
medical image processing
Medical image reconstruction
Medical magnetic resonance imaging
Motion
motion artifacts
NMR IMAGING
patient monitoring
Pneumodyamics, respiration
pneumodynamics
radiation therapy
RADIOLOGY AND NUCLEAR MEDICINE
RADIOTHERAPY
radiotherapy guidance
real‐time imaging
Reconstruction
Respiration
respiratory motion
Spatial resolution
thoracic imaging
Thorax - anatomy & histology
Thorax - physiology
Time Factors
ISSN:0094-2405, 2473-4209, 2473-4209
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Zusammenfassung:Purpose: In this work, the authors present a novel magnetic resonance imaging reconstruction method to improve the quality of MR images in the presence of respiratory motion for real‐time thoracic image‐guided radiotherapy. Methods: This new reconstruction method is called dynamic keyhole and utilizes a library of previously acquired, peripheral k‐space datasets from the same (or similar) respiratory state in conjunction with central k‐space datasets acquired in real‐time. Internal or external respiratory signals are utilized to sort, match, and combine the two separate peripheral and central k‐space datasets with respect to respiratory displacement, thereby reducing acquisition time and improving image quality without respiratory‐related artifacts. In this study, the dynamic keyhole, conventional keyhole, and zero‐filling methods were compared to full k‐space acquisition (ground truth) for 60 coronal datasets acquired from 15 healthy human subjects. Results: For the same image‐quality difference from the ground‐truth image, the dynamic keyhole method reused 79% of the prior peripheral phase‐encoding lines, while the conventional keyhole reused 73% and zero‐filling 63% (p‐value < 0.0001), corresponding to faster acquisition speed of dynamic keyhole for real‐time imaging applications. Conclusions: This study demonstrates that the dynamic keyhole method is a promising technique for clinical applications such as image‐guided radiotherapy requiring real‐time MR monitoring of the thoracic region. Based on the results from this study, the dynamic keyhole method could increase the temporal resolution by a factor of five compared with full k‐space methods.
Bibliographie:Telephone: 61 2 9351 3385; Fax: 61 2 9351 4018.
taeho4kim@gmail.com
Author to whom correspondence should be addressed. Electronic mail
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ISSN:0094-2405
2473-4209
2473-4209
DOI:10.1118/1.4883882