DYNAMIC MR DIGITAL SUBTRACTION ANGIOGRAPHY USING CONTRAST ENHANCEMENT, FAST DATA-ACQUISITION, AND COMPLEX SUBTRACTION

A dynamic MR angiography technique, MR digital subtraction angiography (MR DSA), is proposed using fast acquisition, contrast enhancement, a nd complex subtraction, When a bolus of contrast is injected into a pa tient, data acquisition begins, dynamically acquiring a thick slab usi ng a fast gradient echo sequence for 10-100 s, Similar to x-ray DSA, a mask is selected from the images without contrast enhancement, and la ter images are subtracted from the mask to generate angiograms. Comple x subtraction is used to overcome the partial volume effects related t o the phase difference between the flowing and stationary magnetizatio n in a voxel, Vessel signal is the enhancement of flow magnetization r esulting from the contrast bolus, MR DSA was performed in 28 patients, including vessels in the lungs, brains, legs, abdomen, and pelvis, Al l targeted vessels were well depicted with MR DSA, Corresponding dynam ic information (contrast arrival time t(a) and duration of the arteria l phase t(av)) was measured: t(a)/t(av) = 3.4/4.7 s for the lung, 10.3 /4.9 s for the brain, 12.8/19.3 for the aorta, 15.2/12.6 s for the leg , MR DSA can provide dynamic angiographic images using a very short ac quisition time.