Detailed knowledge of myocardial dynamics is central to understanding normal cardiac physiology and motion abnormalities are closely correlated with many cardiac pathologies. Much of what has been learned concerning myocardial dynamics has been though the use of invasive techniques which can track individual myocardial segments. Current noninvasive techniques have not been able to exactly reproduce these data, in part because they do not follow individual segments and may confuse bulk motion with wall thickening. While other MRI methods offer promise to partially address these limitations through the use of magnetic myocardial tagging, they have limited spatial and temporal resolution, are unable to examine the entire cardiac cycle, and require long examination times. We propose to overcome these limitations through the development, evaluation and validation of acquisition and analysis methods based on phase contrast MRI maps of myocardial velocity. This novel approach allows arbitrarily positioned regions, as small as a few cubic mm, to be selected retrospectively anywhere in the heart and followed in d-D throughout the entire cardiac cycle. Further, instantaneous regional strain, shear, torsion and twist can be measured directly without requiring sophisticated pattern recognition algorithms. The method will be thoroughly evaluated through the use of phantoms and by comparison with fluoroscopic measurements in animals and patients who have had radiopaque markers implanted at the time of surgery. Myocardial dynamics after surgery will be studied in patients and animals, and the myocardial mechanics of the normal and transplanted human heart will be evaluated. Once validated, this technique should allow the noninvasive study of myocardial motion with unprecedented resolution and scope, and can be made available to MRI centers throughout the world. The proposed phase contrast MRI techniques could have a significant impact in the understanding of normal myocardial function, in the evaluation of cardiac pathologies in patients, and in the choice, impact and timing of therapy.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL046347-02
Application #
3365459
Study Section
Diagnostic Radiology Study Section (RNM)
Project Start
1992-02-01
Project End
1995-01-31
Budget Start
1993-02-01
Budget End
1994-01-31
Support Year
2
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Stanford University
Department
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Markl, Michael; Draney, Mary T; Miller, D Craig et al. (2005) Time-resolved three-dimensional magnetic resonance velocity mapping of aortic flow in healthy volunteers and patients after valve-sparing aortic root replacement. J Thorac Cardiovasc Surg 130:456-63
Markl, Michael; Reeder, Scott B; Chan, Frandics P et al. (2004) Steady-state free precession MR imaging: improved myocardial tag persistence and signal-to-noise ratio for analysis of myocardial motion. Radiology 230:852-61
Markl, Michael; Draney, Mary T; Hope, Michael D et al. (2004) Time-resolved 3-dimensional velocity mapping in the thoracic aorta: visualization of 3-directional blood flow patterns in healthy volunteers and patients. J Comput Assist Tomogr 28:459-68
Markl, Michael; Pelc, Norbert J (2004) On flow effects in balanced steady-state free precession imaging: pictorial description, parameter dependence, and clinical implications. J Magn Reson Imaging 20:697-705
Draney, Mary T; Arko, Frank R; Alley, Marcus T et al. (2004) Quantification of vessel wall motion and cyclic strain using cine phase contrast MRI: in vivo validation in the porcine aorta. Magn Reson Med 52:286-95
Markl, M; Alley, M T; Pelc, N J (2003) Balanced phase-contrast steady-state free precession (PC-SSFP): a novel technique for velocity encoding by gradient inversion. Magn Reson Med 49:945-52
Markl, Michael; Chan, Frandics P; Alley, Marcus T et al. (2003) Time-resolved three-dimensional phase-contrast MRI. J Magn Reson Imaging 17:499-506
Bammer, R; Markl, M; Barnett, A et al. (2003) Analysis and generalized correction of the effect of spatial gradient field distortions in diffusion-weighted imaging. Magn Reson Med 50:560-9
Markl, M; Bammer, R; Alley, M T et al. (2003) Generalized reconstruction of phase contrast MRI: analysis and correction of the effect of gradient field distortions. Magn Reson Med 50:791-801
Alley, M T; Napel, S; Amano, Y et al. (1999) Fast 3D cardiac cine MR imaging. J Magn Reson Imaging 9:751-5

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