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The authors compared two techniques for performing runoff, contrast material-enhanced magnetic resonance (MR) angiography. Multiinjection time-resolved imaging of contrast kinetics (TRICKS) and single-injection bolus-chase MR angiographic examinations were performed in 10 volunteers and 10 patients. Image quality and venous overlay of the major blood vessels of the abdomen, thigh, and calf were evaluated. Significantly more (P <.05) vessels were depicted with diagnostic quality on multiinjection TRICKS than on single-injection bolus-chase MR angiographic images.

Purpose: To evaluate the feasibility of using magnetic resonance (MR) imaging to guide and monitor endovascular therapeutic procedures., Materials and Methods: Endovascular therapeutic procedures were performed with MR imaging guidance in eight dogs by using a 1.5-T MR unit with echo-planar imaging capabilities. Carotid arterial aneurysms were surgically created in four dogs. The ability to depict, track, and position catheters, guide wires, and Guglielmi detachable coils was assessed. Catheters were first positioned with fluoroscopic guidance. Tracking and depiction were achieved with MR imaging by using commercially available catheters filled with a gadopentetate dimeglumine solution and a fast, two-dimensional, time-resolved, variable-rate k-space sampling technique., Results: When either a catheter or the coaxial space between a catheter and a guide wire was filled with a solution of gadopentetate dimeglumine, catheter movement was always depicted. In the animals with aneurysms, it was possible to depict movement of a catheter into and out of the aneurysm. This was achieved by superimposing reconstructed images obtained during catheter movement onto a previously acquired MR angiogram ("road map"). Prototype Guglielmi detachable coils were successfully positioned and detached. Aneurysm obliteration was monitored with the acquisition of new road map images., Conclusion: The results demonstrate the feasibility of using MR imaging to guide endovascular therapeutic procedures.

The excellent linearity of digital image storage and retrieval permits hybrid analog-digital subtraction to extend the spatial resolution of two previously developed algorithms which employed entirely digital apparatus. A low resolution, time-integrated preinjection digital mask image is reconverted to analog form and subtracted from live analog video images of iodine administered by peripheral intravenous injection to produce a high resolution display of the cardiovascular system with contrast ten times greater than conventional fluoroscopy. Preliminary studies in dogs are compared with images obtained with our digital subtraction algorithms.

K-edge subtraction images have been produced using a digital video image processor. Images formed by three filtered x-ray beams are detected by an image intensifier-Plumbicon system, digitilized, and combined in real time to produce bone- and tissue-free K-edge subtraction images of iodinated structures. Preliminary studies of rhesus monkey cranial, spinal, and abdominal structures are compared with those of conventional radiography.