Optimization of contrast-enhanced MR angiography : basic and clinical investigations

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In an attempt to optimize MR angiography, we performed the following imaging experiments using 1.5-T clinical MR system and 4.7-T experimental MR system : (1) we designed and made vascular models which have steady, pulsatile, and turbulent flows ; (2) we imaged the vascular models using time-of-flight, phase contrast, and contrast-enhanced MR angiography, and investigated the optimal pulse sequences (including repetition time, echo time, flip angle, and flow sensitivity) and injection methods of contrast medium ; (3) we imaged various vessels of animals using time-of-flight, phase contrast, and contrast-enhanced MR angiography, and investigated the optimal pulse sequences and injection methods of contrast medium ; and, (4) we made artificial stenoses in the vascular models and animal vessels, and investigated the optimal pulse sequence and injection methods of contrast medium to evaluate the stenoses with MR angiography.We performed the optimized MR angiography for patients suspected of having vasculardiseases, compared the findings with conventional angiographic findings, and evaluated the diagnostic accuracy of MR angiography. Optimized MR angiography and contrast-enhanced MR angiography clearly depicted the cerebrovascular lesions (moyamoya disease) and aortic lesions (Takayasu arteritis), and showed a high accuracy for the diagnosis of cerebrovascular and aortic diseases. Optimized contrast-enhanced MR angiography clearly depicted head and neck hemangiomas, and it was able to show the diagnosis and subtype of hemangiomas.We are performing MR angiography that was optimized for various vascular diseases.Furthermore, we are planning to optimize MR angiography for arteries and veins in each site of the whole body.