Magnetic resonance imaging
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Randomized Controlled Trial
Sequential prostate MRI reporting in men on active surveillance: initial experience of a dedicated PRECISE software program.
There is interest in using sequential multiparametric magnetic resonance imaging (mpMRI) to assess men on active surveillance (AS) for prostate cancer. The Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) recommendations propose standardised reporting mpMRI data for these men. This includes accurate size measurements of lesions over time, but such approach is time consuming for the radiologist and there is a strong need of dedicated tools to report serial scans in a systematic manner. We present the results from an initial validation cohort using dedicated PRECISE reporting software to allow automated comparison between sequential scans on AS. ⋯ We conclude that a dedicated PRECISE reporting tool for sequential scans in men on AS results in a significant reduction in the reporting time and allows the radiologist to easily compare scans over time. This tool will help with our understanding of the natural history of mpMRI changes during AS.
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Quantitative susceptibility mapping (QSM) is a means to obtain direct measurements of local tissue susceptibility distribution. Usually the focus is on imaging tissues in the brain, and the region of the brain studied is dictated by an eroded skull stripped mask. Producing the pristine local phase behavior for regions at the edge of the brain has been difficult in the past. ⋯ The mean and standard deviation inside the SSS for all volunteers was 435 ± 5 ppb (this is the inter-subject error). To validate the proposed approach, the mean susceptibility inside the straight sinus showed good agreement between conventional approach and the proposed method. The results presented in this study indicate the potential of generating the susceptibility map for the whole brain, including the SSS (as well as potentially all the cortical veins).
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A 2D gradient-echo EPI is commonly employed for arterial spin labeling (ASL) readout to achieve fast whole brain coverage measurements. However, such a readout suffers from susceptibility artifacts induced by magnetic field inhomogeneities. To reduce these susceptibility effects, single-shot spin-echo EPI was proposed to be used for acquisitions in continuous ASL (CASL). ⋯ Motor cortex activations derived from a finger-tapping task and functional networks from resting state fMRI were compared for both GE and SE contrasts. Direct comparison of SE and GE contrasts revealed that GE ASL provides an improved sensitivity of functional activity in finger-tapping and in resting-state imaging. SE ASL, on the other hand, suffered less from susceptibility artifacts induced by magnetic field inhomogeneities and pulsatile flow artifacts.
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In this work, we characterize contrast origins and noise contributions of spin echo (SE) EPI BOLD signal at 3 T. SE BOLD is a fMRI method of choice for imaging brain regions affected by susceptibility artifacts at lower fields, but its sensitivity remains a limiting factor for whole-brain imaging. To resolve this, the signal and noise contributions as well as TE dependence of SE EPI are characterized in this study. ⋯ To summarize, a new SE-BOLD model was proposed to characterize SE-BOLD contrast and physiological noise contribution at 3 T. Results suggests that SE-BOLD sensitivity can be improved by using shorter TEs, making it a more attractive choice for fMRI, especially in regions with susceptibility artifacts. Such optimizations could also help extend the application of SE BOLD to WM fMRI studies.