Prospective navigator correction of image position for coronary MR angiography.

Danias, Peter G.; McConnell, Michael V.; Khasgiwala, Vaibhav C.; Chuang, Michael L; Edelman, Robert R.; Manning, W. J.

doi:10.1148/radiology.203.3.9169696

Cited by 245 publications

(185 citation statements)

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“…In particular, the free-breathing 3D viability images delineated the MI (21/23 ϭ 91.3%) and all linear hyperenhancing myocardium, because of their high spatial resolution and the high CNR between LV blood and subendocardial hyperenhancing myocardium. This high CNR between the LV blood and hyperenhancing myocardium might be attributed to the suppression of blood signals because of the volumetric excitation and reduced inflow effect in the 3D viability imaging (13,15). Another possible reason for the high CNR between the LV blood and hyperenhancing myocardium was the washout of gadolinium from the LV blood because of the longer delay time and scan time of the free-breathing 3D viability imaging.…”

Section: Discussionmentioning

confidence: 99%

“…All three patients had HCM, and we did not confirm the relationship between the failure of navigator gating and this disease, while they tended to present with transient arrhythmia or dyspnea. The failure of navigator gating has been observed in patients with other myocardial diseases examined using free-breathing 3D viability MRI at 1.5T, probably because of mechanical errors or irregular respiratory or cardiac rhythm of patients (11,15,20). Second, the free-breathing 3D viability images failed to detect about one-third of the patchy hyperenhancing myocardium.…”

Section: Discussionmentioning

confidence: 99%

“…In this free-breathing 3D viability imaging, a k-space weighted navigator-gating technique in combination with a real-time adaptive correction of the imaged 3D volume was used in the craniocaudal direction for the suppression of respiratory artifacts (15,16). A 2D pencil-beam navigator was placed on the right diaphragm and the navigator window was 5-7 mm in the 1/4 center of k-space, and up to 9 -14 mm displacement was permitted for data acquisition in the outer 3/4 k-space.…”

Section: Mrimentioning

confidence: 99%

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Free‐breathing high‐spatial‐resolution delayed contrast‐enhanced three‐dimensional viability MR imaging of the myocardium at 3.0T: A feasibility study

Amano

Matsumura

Kumita

2008

Magnetic Resonance Imaging

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Purpose:To assess the feasibility of free-breathing highspatial-resolution delayed contrast-enhanced three-dimensional (3D) viability magnetic resonance imaging (MRI) at 3.0T for the detection of myocardial damages. Materials and Methods:Twenty-five patients with myocardial diseases, including myocardial infarction and cardiomyopathies, were enrolled after informed consent was given. Free-breathing 3D viability MRI with high spatial resolution (1.5 ϫ 1.25 ϫ 2.5 mm) at 3.0T, for which cardiac and navigator gating techniques were employed, was compared with breath-hold two-dimensional (2D) viability imaging (1.77 ϫ 1.18 ϫ 10 mm) for assessment of contrastto-noise ratio (CNR) and myocardial damage.Results: Free-breathing 3D viability imaging was achieved successfully in 21 of the 25 patients. This imaging technique depicted 84.6% of hyperenhancing myocardium with a higher CNR between hyperenhancing myocardium and blood and with excellent agreement for the transmural extension of myocardial damage (k ϭ 0.91). In particular, the 3D viability images delineated the myocardial infarction and linear hyperenhancing myocardium, comparable to the 2D viability images. Conclusion:Free-breathing high-spatial-resolution delayed contrast-enhanced 3D viability MRI using 3.0T was feasible for the evaluation of hyperenhancing myocardium, as seen with myocardial infarction and cardiomyopathies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Mrimentioning

confidence: 99%

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Free‐breathing high‐spatial‐resolution delayed contrast‐enhanced three‐dimensional viability MR imaging of the myocardium at 3.0T: A feasibility study

Amano

Matsumura

Kumita

2008

Magnetic Resonance Imaging

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“…One study using a qualitative analysis reported that an FB scan is superior to a BH scan (36). One advantage of an FB acquisition is the inherent lack of slice misregistration.…”

Section: Discussionmentioning

confidence: 99%

Free‐breathing delayed hyperenhanced imaging of the myocardium: A clinical application of real‐time navigator echo imaging

Goldfarb

Shinnar

2006

Magnetic Resonance Imaging

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Purpose:To compare a free-breathing (FB) acquisition with the current standard of breath-holding (BH) in a clinical setting using identical two-dimensional MR pulse sequences for imaging of myocardial delayed hyperenhancement. Materials and Methods:Two-dimensional gadolinium-enhanced images were acquired using FB and BH techniques in 18 subjects to evaluate delayed enhancement of myocardial infarction. The FB acquisition used a navigator echo to monitor the position of the right hemidiaphragm for respiratory gating and correction. Visual analysis using a 16-segment model, quantitative signal difference to noise ratios, and percent left ventricle (LV) viability measurements for the two acquisition types were statistically compared.Results: An excellent agreement between two-dimensional BH and two-dimensional FB acquisitions was found. In one patient, a nontransmural infarct was seen only in the FB images. There were no statistically significant differences in the number of infarcted segments or the measured signal difference to noise ratios (SDNR) between the two methods. Linear regression and Bland Altman analysis of the percentage LV viable myocardium yielded a good fit and narrow limits of agreement. Conclusion:An FB navigator echo acquisition can be effectively used in the setting of myocardial delay hyperenhanced imaging. Image quality is similar or superior to that of BH imaging. RECENT STUDIES have shown that reversible myocardial dysfunction can be identified using gadoliniumenhanced MRI (1-5). Images of the myocardium are made after a delay of several minutes following T1 shortening contrast agent administration; this technique is often called "delayed hyperenhanced (DHE) imaging." Nonviable tissue is identified as having a slightly higher concentration than viable tissue of an intravenously injected gadolinium contrast agent. An inversion recovery (IR) T1 weighted sequence (6) is used to minimize the signal intensity from viable myocardium. The inversion time (TI) parameter of the pulse sequence, which is the time between the inversion pulse and the acquired data, is adjusted to minimize the image intensity of healthy myocardium. In these images, nonviable myocardium is identified as hyperenhancing regions.To reduce or eliminate artifacts from motion of the heart during the normal respiratory cycle, image data are most commonly acquired over several heartbeats using pulse sequences synchronized with the cardiac cycle and during suspended respiration. Two-dimensional breath-hold (BH) IR spoiled gradient-echo imaging has been validated in animal models and human studies (7-10) and is currently the standard of reference for MR DHE imaging. Since one slice is acquired each BH, this technique requires many breath-holds for the evaluation of the entire left ventricle. Single-slice BH MRI techniques (11,12) have been proposed and adopted to reduce acquisition time, increase image contrast, resolution, or spatial coverage, but BH-DHE techniques remain limited by BH time and patient cooperation.Free-breathing (F...

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“…The adverse impact of breathing-induced myocardial bulk motion can be minimized by the use of breathholding (1)(2)(3)(4)(5) or by the application of respiratory gating with MR navigators (6 -12). Further refinements in navigator technology have included prospective adaptive motion correction (9,10) in conjunction with navigator displacement-dependent 2D reordering of the acquired k yprofiles in k-space (13,14).…”

mentioning

confidence: 99%

Motion artifact reduction and vessel enhancement for free‐breathing navigator‐gated coronary MRA using 3D k‐space reordering

Huber

Hengesbach

Botnar

et al. 2001

Magnetic Resonance in Med

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Breathing-induced bulk motion of the myocardium during data acquisition may cause severe image artifacts in coronary magnetic resonance angiography (MRA). Current motion compensation strategies include breath-holding or free-breathing MR navigator gating and tracking techniques. Navigator-based techniques have been further refined by the applications of sophisticated 2D k-space reordering techniques. A further improvement in image quality and a reduction of relative scanning duration may be expected from a 3D k-space reordering scheme. Therefore, a 3D k-space reordered acquisition scheme including a 3D navigator gated and corrected segmented kspace gradient echo imaging sequence for coronary MRA was implemented. This new zonal motion-adapted acquisition and reordering technique ( Coronary MR angiography (MRA) image quality is heavily dependent on the suppression of breathing-related motion artifacts. The adverse impact of breathing-induced myocardial bulk motion can be minimized by the use of breathholding (1-5) or by the application of respiratory gating with MR navigators (6 -12). Further refinements in navigator technology have included prospective adaptive motion correction (9,10) in conjunction with navigator displacement-dependent 2D reordering of the acquired k yprofiles in k-space (13,14).k-Space reordering techniques take advantage of the inhomogeneous signal distribution in k-space, with highest signal amplitudes in the origin of k-space and gradually decreasing information content in the periphery of k-space (15). However, high-frequency portions of k-space may still contain information relevant to small-diameter structures, such as the coronary arteries. Based on this a priori knowledge, the priority of lines in k-space can be defined by a problem-specific priority function. One such application, among other techniques (6,13,14,16), is motionadapted gating (MAG) for navigator displacement-dependent reordering of k y -profiles in k-space (13). With MAG, "important" profiles are acquired during a small diaphragmatic displacement while profiles of "lesser importance" are subject to broader or larger displacement conditions. Planar 2D phase-reordering methods in 3D coronary MRA minimize respiratory motion artifacts and increase scan efficiency (14). However, these 3D acquisition techniques solely include reordering of the k-space in two dimensions (k x and k y ). We hypothesized that a "true" 3D k-space reordering in conjunction with a 3D imaging approach would lead to further improvements in respiratory motion suppression and a reduction in the relative scanning time.The present study describes a prospective navigatorbased 3D k-space reordering technique. This zonal motionadapted acquisition and reordering technique (ZMART) was developed using simulations of the Bloch equations, and has been validated in phantom and in vivo experiments. Image data were objectively and quantitatively compared, and the preliminary in vivo results are presented. METHODS k-Space ReorderingA prospective adaptive reordering o...

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Prospective navigator correction of image position for coronary MR angiography.

Abstract: Prospective, adaptive navigator correction of image position for free-breathing coronary MR angiography is a promising, novel approach to compensate for respiratory motion.

Cited by 245 publications

References 0 publications

Free‐breathing high‐spatial‐resolution delayed contrast‐enhanced three‐dimensional viability MR imaging of the myocardium at 3.0T: A feasibility study

Free‐breathing high‐spatial‐resolution delayed contrast‐enhanced three‐dimensional viability MR imaging of the myocardium at 3.0T: A feasibility study

Free‐breathing delayed hyperenhanced imaging of the myocardium: A clinical application of real‐time navigator echo imaging

Motion artifact reduction and vessel enhancement for free‐breathing navigator‐gated coronary MRA using 3D k‐space reordering

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