Evaluation Of Pseudocontinuous Arterial Spin Labeling Technique In 1.5 T Mri: A Phantom Study
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Date
2015
Authors
Yusoff, Norain Liyana
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Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
The routine use of arterial spin labeling (ASL) in diagnosis various brain pathology still facing challenges in image acquisition, post processing and analysis of MR images. The application of ASL technique is still much limited in various clinical settings due to relatively lower sensitivity and image coverage compared to other existing method. This study is to review this advanced technique in Magnetic Resonance Imaging (MRI) with the fabricated phantom using pseudocontinuous ASL (pcASL) with better SNR. pcASL is also used in most hardware setup of MRI scanners. The main imaging parameters such as field of view (FOV), slice thickness (ST) and matrix size were evaluated to obtain optimal image acquisition. The T1, T2 weighted images and BRAVO sequences were also investigated in this study. A fabricated flow phantom was scanned with 1.5 T MRI scanner (GE system). Various labeling parameters were evaluated to obtain optimal image quality. The blood mimicking solution was prepared with a combination of 40 % glycerol and 60 % distilled water. The MR image quality was evaluated by measuring the the signal-to-noise ratio (SNR) of each image. The pcASL showed that it provides optimal SNR by applying optimal imaging parameters. The highest SNR value (94.9) was obtained in paediatric carotid artery size and 75 % stenosis with imaging parameters: slice thickness 9 mm, FOV 320 mm x 320 mm and matrix size 256. This study also found that some susceptibility artifacts can be found in the images. This is due to the turbulent flow inside narrow tubes or leakage inside the phantom. Many SNR cannot be obtained due to artifacts. Thus, familiarity with commonly encountered artifacts is important in determining the interpretation of image. Improvement of the SNR in pcASL measurements is crucial so that it could take a more central role in MRI studies.
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Keywords
Arterial Spin Labeling (ASL)