Compressed sensing (CS) may be useful for accelerating data acquisitions in high-resolution fMRI. However, due to the inherent slow temporal dynamics of the hemodynamic signals and concerns of potential statistical power loss, the CS approach for fMRI (CS-fMRI) has not been extensively investigated. To evaluate the utility of CS in fMRI application, we systematically investigated the properties...

BACKGROUND AND PURPOSE Recent work has shown a potential for excessive heating of deep brain stimulation electrodes during MR imaging. This in vitro study investigates the relationship between electrode heating and the specific absorption rate (SAR) of several MR images. METHODS In vitro testing was performed by using a 1.5-T MR imaging system and a head transmit-receive coil, with bilateral ...

Magnetic resonance imaging (MRI) has been available in clinical practice since the early 1980s. From the start MRI was attractive because of the safety of the technique when compared to x ray imaging, as well as the anatomical detail and pathological contrast seen on the images. By the end of the decade MRI had evolved into a useful method for the evaluation of the central nervous and musculosk...

Spin echoes have been known since 1950. Although their formal description by use of the Bloch equations is straightforward, it does not lead to an intuitive understanding of their behavior except for the special cases of 180" or 90" pulses, especially when many pulses are applied before the magnetization has returned into thermal equilibrium. The extended-phasegraph algorithm, which takes into ...

BACKGROUND AND PURPOSE Enhancing lesions on brain MR imaging can present a diagnostic quandary as both benign lesions such as brain capillary telangiectasia and pathologic lesions such as demyelination may appear similar. Stagnation of blood in low-flow venous channels of brain capillary telangiectasias results in susceptibility effect secondary to the increased local deoxyhemoglobin. Both T2* ...

OBJECTIVES To evaluate hepatic fat fraction on dual- and triple-echo gradient-recalled echo MRI sequences in healthy children. MATERIALS AND METHODS We retrospectively reviewed the records of children in a medical check-up clinic from May 2012 to November 2013. We excluded children with abnormal laboratory findings or those who were overweight. Hepatic fat fraction was measured on dual- and t...

Learning the basic concepts required to understand magnetic resonance (MR) imaging is a straightforward process. Although the individual concepts are simple, there are many concepts to learn and retain simultaneously; this situation may give the illusion that learning the physics of MR imaging is complicated. It is important for the radiologist who interprets MR images to understand the methods...

Nineteen consecutive patients with spinal intramedullary lesions were studied on a 1.5-T system to compare the quality of T2-weighted spin-echo and gradient-recalled-echo (GRE) pulse sequences. Direct comparisons were made in the sagittal and/or axial planes. Twenty-four studies were performed in the 19 patients. The gradient echoes were usually performed at 300/14 (TR/TE) with a flip angle of ...

PURPOSE To determine the value of the gradient- and spin-echo (GRASE) technique as compared with the fast spin-echo and conventional spin-echo techniques in MR imaging of the brain. METHODS Sixty-six patients with ischemic and neoplastic brain lesions were examined with T2-weighted spin-echo, fast spin-echo, and GRASE sequences. Three independent observers evaluated the contrast characteristi...