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Biomedical subjects

Michael L Wood

Publications and source records attributed to Michael L Wood.

4 recordsLinked to original sources
PubMed2006

New onset heart failure in a 29-year-old: A case report of isolated left ventricular noncompaction.

A previously healthy 29-year-old patient presented with new onset congestive heart failure. Based on findings on transthoracic echocardiogram (TTE) and cardiac magnetic resonance imaging (MRI) at an outside center, the patient was diagnosed as having a dilated cardiomyopathy with structural abnormalities in the ventricular septum and left ventricular (LV) apex suspicious for myocardial tumor. After referral to our center for further management, repeat TTE revealed findings characteristic of left ventricular non-compaction (LVNC) with severely depressed overall LV systolic function. Review of the outside cardiac MRI supported the diagnosis of LVNC. Final management consisted of traditional medical therapy for congestive heart failure, an implantable cardiac defibrillator (ICD), warfarin anticoagulation for the prevention of thromboembolism and referral for cardiac transplant.

Adult↗
PubMed2002

Pulse-wave velocity measured in one heartbeat using MR tagging.

A noninvasive method for measuring the aortic pulse-wave velocity (PWV) in a single heartbeat is introduced. The method sinusoidally tags a column of blood within the vessel, and rapidly acquires a series of 1D projections of the tags as they move (in practice, 64 projections at 4-ms intervals). From these projections, the relative motion of blood at different positions along the vessel is measured. The PWV is obtained by fitting a mathematical model of blood flow to the tag trajectories. Tests of this method in a pulsatile flow phantom are presented using latex and polyurethane tubes. The PWV measured in these tubes was (mean +/- standard deviation) 4.4 +/- 0.5 m/s and 2.3 +/- 0.2 m/s, respectively. The distensibility of each tube was calculated from the PWV (latex = (7 +/- 2) 10(-3) mm Hg(-1), poly. = (25 +/- 4) 10(-3)mmHg(-1)) and found to agree within error with distensibility measurements based on the change of tube area with pressure (latex = (6.3 +/- 0.3) 10(-3)mmHg(-1), poly. = (27 +/- 1) 10(-3) mmHg(-1)). To test its feasibility, the PWV measurement was applied to four normal volunteers. The measured PWV values were 3.9 +/- 0.8 m/s, 3.6 +/- 0.9 m/s, 3.9 +/- 0.5 m/s, and 5.3 +/- 0.8 m/s. By acquiring an independent PWV measurement each heartbeat, errors introduced by arrhythmia and trigger variability appear to be avoided with this method.

Aorta↗
PubMed2002

High-order multiband encoding in the heart.

Spatial encoding with multiband selective excitation (e.g., Hadamard encoding) has been restricted to a small number of slices because the RF pulse becomes unacceptably long when more than about eight slices are encoded. In this work, techniques to shorten multiband RF pulses, and thus allow larger numbers of slices, are investigated. A method for applying the techniques while retaining the capability of adaptive slice thickness is outlined. A tradeoff between slice thickness and pulse duration is shown. Simulations and experiments with the shortened pulses confirmed that motion-induced excitation profile blurring and phase accrual were reduced. The connection between gradient hardware limitations, slice thickness, and flow sensitivity is shown. Excitation profiles for encoding 32 contiguous slices of 1-mm thickness were measured experimentally, and the artifact resulting from errors in timing of RF pulse relative to gradient was investigated. A multiband technique for imaging 32 contiguous 2-mm slices, with adaptive slice thickness, was developed and demonstrated for coronary artery imaging in healthy subjects. With the ability to image high numbers of contiguous slices, using relatively short (1-2 ms) RF pulses, multiband encoding has been advanced further toward practical application.

Arteries↗