Development of a QA phantom and protocol for proton magnetic resonance spectroscopy

Abstract

ABSTRACT:The purpose of this study was to develop a special proton magnetic resonance spectroscopy (1H-MRS) phantom, to establish and verify a quality assurance (QA) protocol, and to perform QA for a MR system. For a complete QA protocol, seven principal quality factors (PQFs) were measured. For evaluation of localization and quantification accuracy, two PQFs which are difficult to measure in commercial phantoms, we developed the layered dumbbell-shaped phantom. The performance sensitivity of our phantom was determined as a function of the voxel size on three occasions over $1 year. All MRS QA factors were optimized on two different MRI/MRS systems. The correlation between the metabolite signal intensity and the metabolite concentration was verified. The seven principal MRS QA factors studied can be used to evaluate MR spectra as well as to measure the stability of MR systems.

Design of a fused phantom for quantitative evaluation of brain metabolites and enhanced quality assurance testing for magnetic resonance imaging and spectroscopy

“…However, the signal intensity test performed for 1.5 T was not done for 3.0 T because of susceptibility effects caused by air bubbles A c c e p t e d M a n u s c r i p t in the phantom (Rice et al, 1998;Woo et al, 2009). This indicates that the changes in VOI positioning and the location in the phantom are sensitive to signal intensity with magnetic field strength and pixel size.…”

“…In addition, the inserted container contents can evaporate and become severely distorted with artifacts that occur from air within the container. This QA test was performed across a series of periods, and the SNR values of NAA in the brain-mimicking solution had an interval between 40 and 50 (SNR in 1.5 T instrument, 20-30) (Woo et al, 2009). Thus, compared to with the concentration and signal intensity of metabolites of the human brain, the results were reasonable (Barker et al, 2001;Wellard et al, 2005).…”

“…Various MRI and MRS phantoms have been developed for metabolite quantification (Rice et al, 1998;Simmons et al, 1998), relaxation times of human brain tissue (Rice et al, 1998), angiography (Krämer et al, 2004), MRI human tissue equivalent (Hattori et al, 2013;Kato et al, 2005;Ikemoto et al, 2011), reproducibility of geometric distortion in MRI (Mizowaki et al, 2000), high-resolution phantom for MRI (Fellner et al, 2001), and MRS QA phantom (Woo et al, 2009). …”

“…A signal intensity test of MRS QA was previously performed changing the VOI position and size (Rice et al, 1998;Hunjan et al, 2003;Woo et al, 2009) using an MRS phantom with layered shape containers filled with brain-mimicking solution. However, the signal intensity test performed for 1.5 T was not done for 3.0 T because of susceptibility effects caused by air bubbles A c c e p t e d M a n u s c r i p t in the phantom (Rice et al, 1998;Woo et al, 2009).…”

Four‐and‐one‐half years' experience in monitoring of reproducibility of an MR spectroscopy system — application of in vitro results to interpretation of in vivo data

“…It is also possible that some change‐points (for example around October 30, 2007) were influenced to some degree by service engineers' interventions. However, precise correlation of the changes observed in our in vitro spectroscopic measurements with the actual changes in hardware performance would require more elaborated and time‐consuming quality control procedures performed in parallel with the presented ones (28) . Although service engineers usually check the performance of MRI systems during the routine visits, Sobol et al (29) found that 80% of the independently evaluated systems revealed deficiencies affecting image quality.…”