Dual Inversion Recovery Research Articles

Assessment of coronary artery disease wall thickening using phase-sensitive black-blood MRI: initial experience for the evaluation of coronary artery disease

Background Coronary arterial wall imaging is a promising non-invasive tool for quantitative assessment of arterial remodeling. Conventional techniques mandate imaging during cardiac rest period as well as nulling the blood signal inside the arterial lumen in order to generate an appropriate lumen-wall contrast. These constraints limited the use of coronary wall imaging. Recently, phase-sensitive dual inversion recovery (PS-DIR) imagingFetal cardiovascular MRI has been hampered by the lack of a reliable cardiac gating signal. A recently proposed solution to this problem is metric optimized gating (MOG)[1] was proposed to alleviate the burden of nulling the blood signal and permitted more timing flexibility in planning for coronary wall imaging. This work investigates the utilization of PS-DIR in the assessment of coronary artery thickening in patients with coronary artery diseases (CAD).

Coronary vessel wall assessment after Kawasaki Disease

2D cross-sectional Dual-Inversion-Recovery (DIR) black-blood imaging of the coronary arteries has been used to assess Kawasaki Disease (KD) (Greil et al. 2007). A 3D coronary black-blood approach, however, has been shown to provide better coverage of the coronary tree (Botnar et al 2001). Furthermore, uptake of gadolinium contrast agent in coronary walls may indicate on-going inflammation or vessel wall fibrosis (Maintz et al, 2006).

Time spatial labeling inversion pulse cerebral MR angiography without subtraction by use of dual inversion recovery background suppression

Time-spatial labeling inversion pulse (time-SLIP), which is a technique of nonenhanced magnetic resonance angiography (MRA) based on arterial spin labeling (ASL), is used in various situations. Although subtraction between the images obtained with and without ASL is usually employed in cerebral time-SLIP MRA, to reduce the imaging time, dual inversion recovery (IR) has been applied for suppression of the background signals in this study. Appropriate timings for the 1st IR, 2nd IR, and the interval of data acquisition were investigated using computer simulation and a phantom experiment. With a short interval of data acquisition, the visibility of the simulated vessel was inadequate because replacement of the suppressed flow was insufficient. With a long interval of data acquisition, the contrast between the vessel and background was reduced. The reasons for this appeared to be the following: the longitudinal magnetization of the replaced flow is reduced because of the prolonged 2nd inversion time, causing a mismatch of the null point between the calculated and the actual values to become prominent. As a result, 3-4 s seemed to be an appropriate interval for data acquisition. Sufficient angiographic information could be obtained by use of dual IR background suppression in a volunteer study. With this technique, cerebral time-SLIP MRA can be performed in half of the imaging time required with the conventional subtraction technique.

Phase-sensitive black-blood coronary vessel wall imaging

Black-blood MR coronary vessel wall imaging may become a powerful tool for the quantitative and noninvasive assessment of atherosclerosis and positive arterial remodeling. Although dual-inversion recovery is currently the gold standard, optimal lumen-to-vessel wall contrast is sometimes difficult to obtain, and the time window available for imaging is limited due to competing requirements between blood signal nulling time and period of minimal myocardial motion. Further, atherosclerosis is a spatially heterogeneous disease, and imaging at multiple anatomic levels of the coronary circulation is mandatory. However, this requirement of enhanced volumetric coverage comes at the expense of scanning time. Phase-sensitive inversion recovery has shown to be very valuable for enhancing tissue-tissue contrast and for making inversion recovery imaging less sensitive to tissue signal nulling time. This work enables multislice black-blood coronary vessel wall imaging in a single breath hold by extending phase-sensitive inversion recovery to phase-sensitive dual-inversion recovery, by combining it with spiral imaging and yet relaxing constraints related to blood signal nulling time and period of minimal myocardial motion.

Dual inversion recovery, ultrashort echo time (DIR UTE) imaging: Creating high contrast for short‐T2 species

Imaging of short-T(2) species requires not only a short echo time but also efficient suppression of long-T(2) species in order to maximize the short-T(2) contrast and dynamic range. This paper introduces a method of long-T(2) suppression using two long adiabatic inversion pulses. The first adiabatic inversion pulse inverts the magnetization of long-T(2) water and the second one inverts that of fat. Short-T(2) species experience a significant transverse relaxation during the long adiabatic inversion process and are minimally affected by the inversion pulses. Data acquisition with a short echo time of 8 mus starts following a time delay of inversion time (TI1) for the inverted water magnetization to reach a null point and a time delay of TI2 for the inverted fat magnetization to reach a null point. The suppression of long-T(2) species depends on proper combination of TI1, TI2, and pulse repetition time. It is insensitive to radiofrequency inhomogeneities because of the adiabatic inversion pulses. The feasibility of this dual inversion recovery ultrashort echo time technique was demonstrated on phantoms, cadaveric specimens, and healthy volunteers, using a clinical 3-T scanner. High image contrast was achieved for the deep radial and calcified layers of articular cartilage, cortical bone, and the Achilles tendon.

Dual stack black blood carotid artery CMR at 3T: application to wall thickness visualization.

BackgroundThe increasing understanding of atherosclerosis as an important risk factor for the development of acute ischemic events like ischemic stroke has stimulated increasing interest in non-invasive assessment of the structure, composition and burden of plaque depositions in the carotid artery wall. Vessel wall imaging by means of cardiovascular magnetic resonance (CMR) is conventionally done by 2D dual inversion recovery (DIR) techniques, which often fail in covering large volumes of interest as required in plaque burden assessment. Although the technique has been extended to 2D multislice imaging, its straight extension to 3D protocols is still limited by the prolonged acquisition times and incomplete blood suppression. A novel approach for rapid overview imaging of large sections of the carotid artery wall at isotropic spatial resolutions is presented, which omits excitation of the epiglottis. By the interleaved acquisition of two 3D stacks with the proposed motion sensitized segmented steady-state black-blood gradient echo technique (MSDS) the coverage of the carotid artery trees on both sides in reasonable scan times is enabled.Results10 patients were investigated with the proposed technique and compared to conventional transversal DIR turbo spin and gradient echo approaches centered at the height of the carotid bifurcation. In all MSDS experiments sufficient black-blood contrast could be obtained over the entire covered volumes. The contrast to noise ratio between vessel and suppressed blood was improved by 73% applying the motion sensitizing technique. In all patients the suspicious areas of vessel wall thickening could be clearly identified and validated by the conventional local imaging approach. The average assessable vessel wall segment length was evaluated to be 18 cm. While in 50% of the cases motion artifacts could be appreciated in the conventional images, none were detected for the MSDS technique.ConclusionThe proposed technique enables the time efficient coverage of large areas of the carotid arteries without compromising wall-lumen CNR to get an overview about detrimental alterations of the vessel wall. Thickening of the vessel wall can be identified and the suspicious segments can be targeted for subsequent high-resolution CMR. The exclusion of the epiglottis may further facilitate reduction of swallowing induced motion artifacts.

Aortic vessel wall magnetic resonance imaging at 3.0 Tesla: A reproducibility study of respiratory navigator gated free‐breathing 3D black blood magnetic resonance imaging

The purpose of this study was to evaluate a free-breathing three-dimensional (3D) dual inversion-recovery (DIR) segmented k-space gradient-echo (turbo field echo [TFE]) imaging sequence at 3T for the quantification of aortic vessel wall dimensions. The effect of respiratory motion suppression on image quality was tested. Furthermore, the reproducibility of the aortic vessel wall measurements was investigated. Seven healthy subjects underwent 3D DIR TFE imaging of the aortic vessel wall with and without respiratory navigator. Subsequently, this sequence with respiratory navigator was performed twice in 10 healthy subjects to test its reproducibility. The signal-to-noise (SNR), contrast-to-noise ratio (CNR), vessel wall sharpness, and vessel wall volume (VWV) were assessed. Data were compared using the paired t-test, and the reproducibility of VWV measurements was evaluated using intraclass correlation coefficients (ICCs). SNR, CNR, and vessel wall sharpness were superior in scans performed with respiratory navigator compared to scans performed without. The ICCs concerning intraobserver, interobserver, and interscan reproducibility were excellent (0.99, 0.94, and 0.95, respectively). In conclusion, respiratory motion suppression substantially improves image quality of 3D DIR TFE imaging of the aortic vessel wall at 3T. Furthermore, this optimized technique with respiratory motion suppression enables assessment of aortic vessel wall dimensions with high reproducibility.

Dual Inversion Recovery Brain Imaging at 3 Tesla: Diagnostic value in the detection of MS lesions

Purpose: To prospectively determine and compare the sensitivity in the detection of multiple sclerosis (MS) lesions using Dual Inversion-Recovery (DIR), fluid-attenuated inversion recovery (FLAIR), and a T2-weighted turbo spin echo (T2 TSE) magnetic resonance imaging (MRI) at 3.0T in patients with suspected and definite MS.

Dual Inversion Recovery MRI Helps Identifying Cortical Tubers in Tuberous Sclerosis

Dual inversion-recovery imaging (DIR) has been advocated for the diagnosis of cortical lesions in epileptic patients. The role of this sequence, however, is not established in tuberous sclerosis patients. We studied prospectively the interest of DIR sequence in four well-documented consecutive tuberous sclerosis patients with focal epilepsy. In all patients, the cortical tubers appeared very bright on this sequence and were well outlined compared with high resolution T2 or FLAIR imaging. In two patients, one cortical tuber was missed on T2 weighted images due to signal intensity close to the CSF. These lesions were better depicted on DIR than on FLAIR. Three cortical lesions from two patients were visualized only on DIR. DIR helped to depict cortical tubers and may have a complementary role in the MRI evaluation of tuberous sclerosis patients. There is a need to compare sensitivity of T2, FLAIR and DIR with a larger population of patients with focal epilepsies.

Dual Inversion Recovery Brain Imaging at 3 Tesla: Diagnostic value in the detection of MS lesions

Purpose: To prospectively determine and compare the sensitivity in the detection of multiple sclerosis (MS) lesions using Dual Inversion-Recovery (DIR), fluid-attenuated inversion recovery (FLAIR), and a T2-weighted turbo spin echo (T2 TSE) magnetic resonance imaging (MRI) at 3.0T in patients with suspected and definite MS.