Abstract
Purpose: The objectives of this study are to develop an magnetic resonance imaging and spectroscopy (MRI-MRS) fused phantom along with the inserts for metabolite quantification and to conduct quantitative analysis and evaluation of the layered vials of brain-mimicking solution for quality assurance (QA) performance, according to the localization sequence. Methods: The outer cylindrical phantom body is made of acrylic materials. The section other than where the inner vials are located was filled with copper sulfate and diluted with water so as to reduce the T1 relaxation time. Sodium chloride was included to provide conductivity similar to the human body. All measurements of MRI and MRS were made using a 3.0 T scanner (Achiva Tx 3.0 T; Philips Medical Systems, Netherlands). The MRI scan parameters were as follows: (1) spin echo (SE) T1-weighted image: repetition time (TR), 500ms; echo time (TE), 20ms; matrix, 256×256; field of view (FOV), 250mm; gap, 1mm; number of signal averages (NSA), 1; (2) SE T2-weighted image: TR, 2,500 ms; TE, 80 ms; matrix, 256×256; FOV, 250mm; gap, 1mm; NSA, 1; 23 slice images were obtained with slice thickness of 5mm. The water signal of each volume of interest was suppressed by variable pulse power and optimizedmore » relaxation delays (VAPOR) applied before the scan. By applying a point-resolved spectroscopy sequence, the MRS scan parameters were as follows: voxel size, 0.8×0.8×0.8 cm{sup 3}; TR, 2,000ms; TE, 35ms; NSA, 128. Results: Using the fused phantom, the results of measuring MRI factors were: geometric distortion, <2% and ±2 mm; image intensity uniformity, 83.09±1.33%; percent-signal ghosting, 0.025±0.004; low-contrast object detectability, 27.85±0.80. In addition, the signal-to-noise ratio of N-acetyl-aspartate was consistently high (42.00±5.66). Conclusion: The MRI-MRS QA factors obtained simultaneously using the phantom can facilitate evaluation of both images and spectra, and provide guidelines for obtaining MRI and MRS QA factors simultaneously. This study was supported by grant (2012-007883 and 2014R1A2A1A10050270) from the Mid-career Researcher Program through the NRF funded by Ministry of Science. In addition, this study was supported by the Industrial R&D of MOTIE/KEIT (10048997, Development of the core technology for integrated therapy devices based on real-time MRI-guided tumor tracking)« less
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