High spatial and temporal resolution neuro and body contrast-enhanced MR angiography.

摘要

Recent advances in acquisition and reconstruction techniques for contrast-enhanced MR Angiography (CE-MRA), such as parallel imaging and view-shared time-resolved sampling patterns, have made high temporal and spatial resolution imaging feasible. The purposes of this work are to assess the fidelity with which view-shared time-resolved acquisitions portray motion and to develop improved methods for high temporal and spatial resolution imaging of the neurovasculature and abdominal vasculature. A computer-controlled motion phantom was used to study the temporal fidelity of 3D time-resolved sequences in portraying an advancing contrast bolus. The centricity and compactness of the sampling of central k-space and the ordering of views for reconstruction were shown to affect the ability to freeze motion within each data acquisition frame. A comprehensive neurovascular exam was developed for imaging of the aortic arch through intracranial vessels using a two part imaging protocol including (i) a low dose (2 ml) time-resolved scan to provide bolus timing and an overview of the vasculature and (ii) a high spatial resolution carotid angiogram and intracranial venogram using a dynamic change of field-of-view. Imaging of the abdominal vasculature was performed using a similar two-part protocol along with high parallel imaging accelerations. The rapid 3D time-resolved test bolus acquisition provided quality (temporal resolution, spatial resolution and SNR) allowing reliable timing and an overview of the vasculature. Applying accelerated imaging to larger contrast volume carotid and renal angiograms allowed for high spatial resolution imaging over an extended field-of-view and decreased scan times compared to clinical standards.