Peripheral vascular disease (PVD) affects 8 million people in the United States, causes significant morbidity, and is associated with cardiovascular mortality. Given that many patients with PVD also suffer from impaired renal function, one must exercise caution in using CE-MRA because of concerns about the risks of nephrogenic systemic fibrosis (NSF), a serious and potentially lethal disorder. Recently, non-enhanced MRA techniques have been proposed to eliminate the risk of NSF. The overall goal of this proposal is to implement a methodology for non-contrast peripheral MRA that is insensitive to the timing of peak systolic flow;moreover, the technology should be fast, insensitive to patient motion, and accurate. For this purpose, we have implemented a novel approach consisting of a fat suppressed, single shot 2D saturation-recovery trueFISP (SR-TFI) pulse sequence. Although this approach for non-contrast MRA has not been previously reported, our initial clinical trials demonstrate excellent results even in the presence of severe PVD. The method does not require prior knowledge of flow patterns and eliminates the need for cine MRI to determine the timing of peak flow velocity, a requirement for FBI. Moreover, the method is less sensitive to patient motion than FBI and has proven robust for imaging of the pelvic arteries. For the small subset of patients in whom it is not possible to synchronize the data acquisition to the cardiac cycle (e.g. due to atrial fibrillation or other cardiac arrhythmias), we propose the use of ungated Ghost MRA. Ghost MRA uses the ghost artifacts generated by pulsatile flow to create an MRA with no signal contribution from background tissues.
Our specific aims are:
Specific Aim 1 : To optimize multi-station flow-insensitive SR-TFI of the peripheral arteries with a total acquisition time <10 minutes using spatial resolution on the order of 1-2 mm3.
Specific Aim 2 : To implement multi-station flow-dependent (Ghost) MRA of the peripheral arteries with an image acquisition time <5 minutes per station using spatial resolution on the order of 1 mm.
Specific Aim 3 : Evaluate non-contrast MRA in comparison with CE-MRA and/or x-ray DSA in patients
We have developed a set of novel technologies that will largely eliminate the need to administer contrast agents during magnetic resonance angiography in order to diagnose peripheral vascular disease. This study will result in better image quality, greater diagnostic accuracy, lower procedure cost, and enhanced patient safety.
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