High Intensity Reduction Research Articles

A New Magnetic Resonance Imaging Method for 2 Tissue Suppression: Double Tissue Suppression With Multiecho Acquisition and Single Inversion Time Combining High-Intensity Reduction (DOMUST-HIRE).

The fluid-attenuated inversion recovery (FLAIR) method is one of the most important magnetic resonance imaging techniques for the brain, and the high-intensity reduction (HIRE) method is an imaging technique to obtain cerebrospinal fluid suppression images by subtracting long echo time images from short echo time images. In contrast, the double inversion recovery technique suppresses 2 types of tissue signals with different T1 values by applying 2 inversion recovery pulses with different inversion times. However, the double inversion recovery method requires the setting of 2 inversion times in a sequence; thus, its use is limited to relatively high-specification equipment. Here, we propose a new sequence called double tissue suppression with multiecho acquisition and single inversion time combining high-intensity reduction (DOMUST-HIRE) that suppresses the 2 tissues by adding single inversion recovery pulses to a sequence based on the HIRE method. In this small clinical study, we performed physical evaluation by imaging a subject's head with FLAIR and DOMUST-HIRE method. The DOMUST-HIRE method can increase the contrast ratio and the contrast-to-noise ratio between white matter (WM) and gray matter, whereas the signal-to-noise ratio between WM and gray matter decreased than with FLAIR method. The DOMUST-HIRE method can be used to suppress WM and cerebrospinal fluid signals.

Improved visualization of diffusion-prepared MR neurography (SHINKEI) in the lumbosacral plexus combining high-intensity reduction (HIRE) technique

PurposeThis study attempted to improve visualization of the pelvic nervous system using the high-intensity reduction (HIRE)-nerve-SHeath signal increased with INKed rest-tissue RARE Imaging (SHINKEI) technique that involves subtracting signals of 3D heavily T2W images from SHINKEI images. We identified the optimum TE value for 3D heavily T2W images and assessed the usefulness of the HIRE-SHINKEI technique. Materials and methodsCoronal lumbosacral plexus images were acquired from six healthy volunteers at 3 T. We optimized the TE of the 3D heavily T2-weighted (T2W) images in HIRE-SHINKEI and compared HIRE-SHINKEI images with conventional SHINKEI images with respect to nerve depiction, and vein, bladder, and cerebrospinal fluid (CSF) signal suppression using a 5-point scale. ResultsIn 3D heavily T2W images optimized by HIRE-SHINKEI technique, the signal corresponding to nerves became significantly lower at TE = 400 ms (p < 0.0005), while that of veins occurred at TE = 400 ms and 600 ms (p < 0.05). The suppression of bladder signals was significant at TE = 400, 600, and 800 ms (p < 0.05); however, there was no difference in signal inhibition from CSF at all TEs tested. Based on these results, an optimal TE of 600 ms was identified for 3D heavily T2W images; these images corresponded to the minimal loss of nerve signal and simultaneous maximum subtraction of signals from the bladder, vein, and CSF with dissimilar T2 values. Compared with SHINKEI images, the optimized HIRE-SHINKEI images selectively delineated nerves in greater detail, and along with significant signal suppression of the bladder (p < 0.0001) and veins (p < 0.05). ConclusionHIRE-SHINKEI can be used to better visualize the lumbosacral plexus with higher signal suppression of other pelvic structures. Such detailed Magnetic resonance neurography and selective depiction of nerves are useful for the diagnosis of peripheral nerve disorders.

HIRE (high intensity reduction)

HIRE (high intensity reduction)

Assessment of cerebral gliomas by a new dark fluid sequence, high intensity REduction (HIRE): a preliminary study.

The purpose of this study was to assess the diagnostic potential of a new dark fluid sequence, high intensity reduction (HIRE) in the diagnostic workup of patients with cerebral gliomas. The HIRE sequence utilizes a very long T(2) value of the cerebrospinal fluid (CSF) to suppress its high signal contribution in T(2)-weighted imaging by a image subtraction technique. Fifteen patients with histologically confirmed cerebral gliomas were examined with T(2)-weighted fast spin-echo (FSE), T(1)-weighted SE, fast fluid-attenuated inversion recovery (FLAIR), and HIRE imaging using identical scan parameters. In patients with enhancing lesions, fast FLAIR and HIRE were added to the contrast-enhanced T(1)-weighted SE images. Images were analyzed in a qualitative and quantitative evaluation. In the qualitative analysis, lesion detection, lesion delineation, and differentiation between enhancing and non-enhancing tumor tissue were assessed in a two-reader study. For the quantitative analysis, lesion-to-background and lesion-to-CSF contrast and contrast-to-noise ratios were determined in a region of interest analysis. HIRE achieved a significant reduction of the CSF signal without losing the high gray-to-white matter contrast of T(2)-weighted sequences. In the quantitative analysis, the contrast ratios of the HIRE images were lower compared with the FLAIR images due to a relatively high background and CSF signal. After administration of contrast media, HIRE images presented a significant signal increase in enhancing lesions, which subsequently increased the contrast and contrast-to-noise ratios. In the qualitative analysis, both readers found all tumors clearly delineated on HIRE imaging. Compared with T(2)-weighted FSE, the tumor delineation with HIRE was better in nine patients, equal in four patients, and less in one patient. Compared with the FLAIR images, HIRE was rated superior in three patients, equal in nine patients, and inferior in another three patients. Delineation of the enhancing tumor parts was possible with HIRE in all patients. HIRE images had significantly fewer image artifacts than FLAIR images due to reduced inflow effects. The T(2)-based HIRE sequence presented is an alternative to the T(1)-based FLAIR sequence, with the advantage of better gray-to-white matter contrast and shorter measurement time. Due to the subtraction technique, signal intensities from tissues with relaxation times in the range T(2 WM) < < T(2) < T(2 CSF) are also gradually affected, corresponding to their T(2) values. With respect to this unwanted effect, an improvement in HIRE imaging will be possible by using a self-weighted subtraction algorithm. In a forthcoming study this concept will first be tested on appropriate phantom fluids.