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23. Correction with blood T1 is essential when measuring post-contrast myocardial T1 value in patients with acute myocardial infarction

Author

Choi Eui-Young, Hwang Sung Ho, Yoon Young Won, Park Chul Hwan, Paek Mun Young, Greiser Andreas, Chung Hyemoon, Yoon Ji-Hyun, Kim Jong-Youn, Min Pil-Ki, Lee Byoung Kwon, Hong Bum-Kee, Rim Se-Joong, Kwon Hyuck Moon, and Kim Tae Hoon

Subjects
Cardiovascular magnetic resonance, T1 mapping, Myocardium, Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Background Post-contrast T1 mapping by modified Look-Locker inversion recovery (MOLLI) sequence has been introduced as a promising means to assess an expansion of the extra-cellular space. However, T1 value in the myocardium can be affected by scanning time after bolus contrast injection. In this study, we investigated the changes of the T1 values according to multiple slicing over scanning time at 15 minutes after contrast injection and usefulness of blood T1 correction. Methods Eighteen reperfused acute myocardial infarction (AMI) patients, 13 cardiomyopathy patients and 8 healthy volunteers underwent cardiovascular magnetic resonance with 15 minute-post contrast MOLLI to generate T1 maps. In 10 cardiomyopathy cases, pre- and post-contrast MOLLI techniques were performed to generate extracellular volume fraction (Ve). Six slices of T1 maps according to the left ventricular (LV) short axis, from apex to base, were consecutively obtained. Each T1 value was measured in the whole myocardium, infarcted myocardium, non-infarcted myocardium and LV blood cavity. Results The mean T1 value of infarcted myocardium was significantly lower than that of non-infarcted myocardium (425.4±68.1 ms vs. 540.5±88.0 ms, respectively, p< 0.001). T1 values of non-infarcted myocardium increased significantly from apex to base (from 523.1±99.5 ms to 561.1±81.1 ms, p=0.001), and were accompanied by a similar increase in blood T1 value in LV cavity (from 442.1±120.7 ms to 456.8±97.5 ms, p0.05). The Ve did not show significant differences from apical to basal slices. Conclusion Post-contrast myocardial T1 corrected by blood T1 or Ve, provide more stable measurement of degree of fibrosis in non-infarcted myocardium in short- axis multiple slicing.

Published
2013
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24. Shortened Modified Look-Locker Inversion recovery (ShMOLLI) for clinical myocardial T1-mapping at 1.5 and 3 T within a 9 heartbeat breathhold

Author

Greiser Andreas, Cochlin Lowri E, Dall'Armellina Erica, Ferreira Vanessa M, Piechnik Stefan K, Neubauer Stefan, and Robson Matthew D

Subjects
Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Background T1 mapping allows direct in-vivo quantitation of microscopic changes in the myocardium, providing new diagnostic insights into cardiac disease. Existing methods require long breath holds that are demanding for many cardiac patients. In this work we propose and validate a novel, clinically applicable, pulse sequence for myocardial T1-mapping that is compatible with typical limits for end-expiration breath-holding in patients. Materials and methods The Shortened MOdified Look-Locker Inversion recovery (ShMOLLI) method uses sequential inversion recovery measurements within a single short breath-hold. Full recovery of the longitudinal magnetisation between sequential inversion pulses is not achieved, but conditional interpretation of samples for reconstruction of T1-maps is used to yield accurate measurements, and this algorithm is implemented directly on the scanner. We performed computer simulations for 100 msIn-vivo myocardial T1-mapping using this method and the previous gold-standard (MOLLI) was performed in 10 healthy volunteers at 1.5T and 3T, 4 volunteers with contrast injection at 1.5T, and 4 patients with recent myocardial infarction (MI) at 3T. Results We found good agreement between the average ShMOLLI and MOLLI estimates for T1 < 1200 ms. In contrast to the original method, ShMOLLI showed no dependence on heart rates for long T1 values, with estimates characterized by a constant 4% underestimation for T1 = 800-2700 ms. In-vivo, ShMOLLI measurements required 9.0 ± 1.1 s (MOLLI = 17.6 ± 2.9 s). Average healthy myocardial T1 s by ShMOLLI at 1.5T were 966 ± 48 ms (mean ± SD) and 1166 ± 60 ms at 3T. In MI patients, the T1 in unaffected myocardium (1216 ± 42 ms) was similar to controls at 3T. Ischemically injured myocardium showed increased T1 = 1432 ± 33 ms (p < 0.001). The difference between MI and remote myocardium was estimated 15% larger by ShMOLLI than MOLLI (p < 0.04) which suffers from heart rate dependencies for long T1. The in-vivo variability within ShMOLLI T1-maps was only 14% (1.5T) or 18% (3T) higher than the MOLLI maps, but the MOLLI acquisitions were twice longer than ShMOLLI acquisitions. Conclusion ShMOLLI is an efficient method that generates immediate, high-resolution myocardial T1-maps in a short breath-hold with high precision. This technique provides a valuable clinically applicable tool for myocardial tissue characterisation.

Published
2010
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25. Aortic valve stenotic area calculation from phase contrast cardiovascular magnetic resonance: the importance of short echo time

Author

Cowan Brett R, Greiser Andreas, Gabriel Ruvin S, O'Brien Kieran R, Young Alistair A, and Kerr Andrew J

Subjects
Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Background Cardiovascular magnetic resonance (CMR) can potentially quantify aortic valve area (AVA) in aortic stenosis (AS) using a single-slice phase contrast (PC) acquisition at valve level: AVA = aortic flow/aortic velocity-time integral (VTI). However, CMR has been shown to underestimate aortic flow in turbulent high velocity jets, due to intra-voxel dephasing. This study investigated the effect of decreasing intra-voxel dephasing by reducing the echo time (TE) on AVA estimates in patients with AS. Method 15 patients with moderate or severe AS, were studied with three different TEs (2.8 ms/2.0 ms/1.5 ms), in the main pulmonary artery (MPA), left ventricular outflow tract (LVOT) and 0 cm/1 cm/2.5 cm above the aortic valve (AoV). PC estimates of stroke volume (SV) were compared with CMR left ventricular SV measurements and PC peak velocity, VTI and AVA were compared with Doppler echocardiography. CMR estimates of AVA obtained by direct planimetry from cine acquisitions were also compared with the echoAVA. Results With a TE of 2.8 ms, the mean PC SV was similar to the ventricular SV at the MPA, LVOT and AoV0 cm (by Bland-Altman analysis bias ± 1.96 SD, 1.3 ± 20.2 mL/-6.8 ± 21.9 mL/6.5 ± 50.7 mL respectively), but was significantly lower at AoV1 and AoV2.5 (-29.3 ± 31.2 mL/-21.1 ± 35.7 mL). PC peak velocity and VTI underestimated Doppler echo estimates by approximately 10% with only moderate agreement. Shortening the TE from 2.8 to 1.5 msec improved the agreement between ventricular SV and PC SV at AoV0 cm (6.5 ± 50.7 mL vs 1.5 ± 37.9 mL respectively) but did not satisfactorily improve the PC SV estimate at AoV1 cm and AoV2.5 cm. Agreement of CMR AVA with echoAVA was improved at TE 1.5 ms (0.00 ± 0.39 cm2) versus TE 2.8 (0.11 ± 0.81 cm2). The CMR method which agreed best with echoAVA was direct planimetry (-0.03 cm2 ± 0.24 cm2). Conclusion Agreement of CMR AVA at the aortic valve level with echo AVA improves with a reduced TE of 1.5 ms. However, flow measurements in the aorta (AoV 1 and 2.5) are underestimated and 95% limits of agreement remain large. Further improvements or novel, more robust techniques are needed in the CMR PC technique in the assessment of AS severity in patients with moderate to severe aortic stenosis.

Published
2009
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27. Dental-dedicated MRI, a novel approach for dentomaxillofacial diagnostic imaging: technical specifications and feasibility

Author

Greiser, Andreas, primary, Christensen, Jennifer, additional, Fuglsig, João M C S, additional, Johannsen, Katrine M, additional, Nixdorf, Donald R, additional, Burzan, Kim, additional, Lauer, Lars, additional, Krueger, Gunnar, additional, Hayes, Carmel, additional, Kettless, Karen, additional, Ulrici, Johannes, additional, and Spin-Neto, Rubens, additional

Published
2023
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30. Scar Characterization to Predict Life-Threatening Arrhythmic Events and Sudden Cardiac Death in Patients With Cardiac Resynchronization Therapy: The GAUDI-CRT Study

Author

Acosta, Juan, Fernández-Armenta, Juan, Borràs, Roger, Anguera, Ignasi, Bisbal, Felipe, Martí-Almor, Julio, Tolosana, Jose M., Penela, Diego, Andreu, David, Soto-Iglesias, David, Evertz, Reinder, Matiello, María, Alonso, Concepción, Villuendas, Roger, de Caralt, Teresa M., Perea, Rosario J., Ortiz, Jose T., Bosch, Xavier, Serra, Luis, Planes, Xavier, Greiser, Andreas, Ekinci, Okan, Lasalvia, Luis, Mont, Lluis, and Berruezo, Antonio

Published
2018
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48. Dental-dedicated MRI, a novel approach for dentomaxillofacial diagnostic imaging: technical specifications and feasibility.

Author

Greiser, Andreas, Christensen, Jennifer, Fuglsig, João M C S, Johannsen, Katrine M, Nixdorf, Donald R, Burzan, Kim, Lauer, Lars, Krueger, Gunnar, Hayes, Carmel, Kettless, Karen, Ulrici, Johannes, and Spin-Neto, Rubens

Subjects
TECHNICAL specifications, DIAGNOSTIC imaging, MAGNETIC resonance imaging, MEDICAL equipment design, BRAIN imaging
Abstract

MRI is a noninvasive, ionizing radiation-free imaging modality that has become an indispensable medical diagnostic method. The literature suggests MRI as a potential diagnostic modality in dentomaxillofacial radiology. However, current MRI equipment is designed for medical imaging (eg, brain and body imaging), with general-purpose use in radiology. Hence, it appears expensive for dentists to purchase and maintain, besides being complex to operate. In recent years, MRI has entered some areas of dentistry and has reached a point in which it can be provided following a tailored approach. This technical report introduces a dental-dedicated MRI (ddMRI) system, describing how MRI can be adapted to fit dentomaxillofacial radiology through the appropriate choice of field strength, dental radiofrequency surface coil, and pulse sequences. Also, this technical report illustrates the possible application and feasibility of the suggested ddMRI system in some relevant diagnostic tasks in dentistry. Based on the presented cases, it is fair to consider the suggested ddMRI system as a feasible approach to introducing MRI to dentists and dentomaxillofacial radiology specialists. Further studies are needed to clarify the diagnostic accuracy of ddMRI considering the various diagnostic tasks relevant to the practice of dentistry. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Fully-automated left ventricular mass and volume MRI analysis in the UK Biobank population cohort: evaluation of initial results

Author

Suinesiaputra, Avan, Sanghvi, Mihir M., Aung, Nay, Paiva, Jose Miguel, Zemrak, Filip, Fung, Kenneth, Lukaschuk, Elena, Lee, Aaron M., Carapella, Valentina, Kim, Young Jin, Francis, Jane, Piechnik, Stefan K., Neubauer, Stefan, Greiser, Andreas, Jolly, Marie-Pierre, Hayes, Carmel, Young, Alistair A., and Petersen, Steffen E.

Published
2018
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