CViL (McVeigh Lab) Research
Measurement of LV Function with dynamic CT
SQUEEZ is a new method for measuring local myocardial function with 4DCT data. The method tracks the relative motions of the trabecular tissues on the endocardium, as measured from the LV blood pool signal, to obtain a local estimate of LV function. During contrast injection, the LV blood pool yields a very bright 3D object whose surface represents a “cast” of the LV endocardium. CT images are obtained at multiple time points in the heart cycle from end-diastole through end-systole. For each time point the bright LV blood pool is extracted using simple automatic thresholding yielding a set of 3D “casts”. Each cast is a 2D surface imbedded in 3D; when a movie of the surfaces is viewed it is obvious that certain geometric features such as local valleys and ridges are acting as fiducial markers on the surface. These markers are tracked and the deformation on the endocardium is calculated as Regional Shortening from CT (RSCT)
Development of novel techniques to provide new possibilities from MR and CT imaging
The McVeigh lab has created new MRI techniques that have broken through barriers in scanning speed by optimizing hardware and designing novel pulse sequences. These methods opened up the first available technique to obtain cardiac function with MR during a breath-hold, and also lead to real-time MR imaging techniques used for guiding therapy, measuring perfusion with MR during contrast injection, and measuring skeletal muscle contraction in real-time. In addition, Dr. McVeigh’s laboratory has explored self-gated and motion compensation techniques to push the boundaries of spatial resolution in moving tissues such as the heart. These motion compensation methods have tremendous implications for modeling post-infarct function and electrophysiology for individual patients. Recently the McVeigh lab has developed method for the automatic evaluation of local ventricular function from a single heartbeat using data obtained during a cardiac coronary CT angiogram.
Development of tagged MRI to precisely image local myocardial function
Dr. McVeigh and his trainees have developed novel pulse sequences and image analysis techniques to use MRI tagging to measure local myocardial function. Working in close collaboration with Elias Zerhouni and other clinical colleagues and clinical trainees at Johns Hopkins, these techniques were used to fully characterize normal and ischemic myocardial function in both large animal models and humans. MRI tagging has become the gold standard method for accurate measurement of myocardial function.
Simultaneous measurement of electrical and mechanical activity in the normal, dyssynchronous and infarcted heart
Dr. McVeigh’s laboratory has developed custom hardware, pulse sequences, experimental protocols and image analysis methods to perform MRI tagging in the ectopically paced heart, and to measure electrical activity on the surface of the heart with an electrode sock during MRI tagging. These techniques have been used to understand cardiac dyssynchrony, and the effect of pacing protocol in Cardiac Resynchronization Therapy (CRT). These techniques have also been used to measure LV arrhythmia in the setting of LV scar, with high-resolution scar images providing the substrate for sophisticated 4D computer models of the entire LV. These techniques have lead to the development of precise modeling of mechanics for individual patients.
Application of novel MRI methods to heart failure and post-infarct patients
Understanding which patients will respond to Cardiac Resynchronization Therapy (CRT) remains an open problem in treating heart failure. The McVeigh lab working with cardiologists at Johns Hopkins derived a metric called “CURE” which to date is the best predictor of patient response to CRT. CURE has been successfully implemented by a number of independent groups. Also, using high resolution imaging with motion compensation techniques the McVeigh lab has provided ultra high-resolution images of infarcts in the human heart in vivo and in vitro; these efforts have helped develop models of the post-infarct heart that will have impact on the personalized treatment regime for individual patients.
Real-time MRI guided therapy
During his tenure at NIH, Dr. McVeigh worked in close collaboration with industrial partners to create ultra-fast interactive MRI scanning techniques and MRI compatible interventional devices to perform pioneering work in MRI guided interventional therapy. In collaboration with clinical colleagues at Hopkins and NIH, his laboratory performed the first MRI guided radio-frequency ablation of myocardial tissue, the first MRI guided direct injections of stem cells into the beating heart, and the first minimally invasive MRI guided delivery of a prosthetic aortic valve into the beating heart. Many of the techniques and hardware developed are now incorporated into commercial MRI systems.