Abstract
Non‐Cartesian magnetic resonance imaging (MRI) sequences have shown great promise for abdominal examination during free breathing, but break down in the presence of bulk patient motion (i.e. voluntary or involuntary patient movement resulting in translation, rotation or elastic deformations of the body). This work describes a data‐consistency‐driven image stabilization technique that detects and excludes bulk movements during data acquisition. Bulk motion is identified from changes in the signal intensity distribution across different elements of a multi‐channel receive coil array. A short free induction decay signal is acquired after excitation and used as a measure to determine alterations in the load distribution. The technique has been implemented on a clinical MR scanner and evaluated in the abdomen. Six volunteers were scanned and two radiologists scored the reconstructions. To show the applicability to other body areas, additional neck and knee images were acquired. Data corrupted by bulk motion were successfully detected and excluded from image reconstruction. An overall increase in image sharpness and reduction of streaking and shine‐through artifacts were seen in the volunteer study, as well as in the neck and knee scans. The proposed technique enables automatic real‐time detection and exclusion of bulk motion during MR examinations without user interaction. It may help to improve the reliability of pediatric MRI examinations without the use of sedation.
Highlights
Motion poses a key challenge for diagnostic three‐dimensional (3D) magnetic resonance (MR) examination of the abdomen
A variety of techniques for motion‐robust abdominal imaging have been proposed in the literature, the occurrence of bulk motion still poses an unresolved problem and can result in non‐diagnostic image quality or misinterpretation of images
This work describes a time‐efficient method for automatic detection and exclusion of bulk motion during volumetric abdominal MR examination
Summary
Motion poses a key challenge for diagnostic three‐dimensional (3D) magnetic resonance (MR) examination of the abdomen. Both physiological motion, such as respiratory and cardiac motion, and bulk motion, caused by bulk body movements or coughing, can impair the image quality and result in non‐diagnostic images.[1,2,3] Various strategies have been proposed to handle physiological motion‐related artifacts. General anesthesia or deep sedation is often necessary to obtain diagnostic images in Abbreviations used: AF, artifacts; CC, correlation coefficient; CHESS, chemical shift selective; FFT, fast Fourier transformation; FID, free induction decay; FOV, field of view; HIPAA, Health Insurance Portability and Accountability Act; ICE, image calculation environment; IRB, Institutional Review Board; IQ, image quality; LE, liver edge sharpness and hepatic vessel clarity; MR, magnetic resonance; MRI, magnetic resonance imaging; RF, radiofrequency; SAD, sum of absolute differences; 3D, three‐dimensional Bjorn Stemkens and Thomas Benkert contributed to this work
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