MRA throws down gauntlet to DSA in neurovascular disease

High-field 3D MR angiography can put up a good fight against conventional x-ray digital subtraction angiography for the diagnosis of brain aneurysms and other intracranial vascular malformations, according to studies presented at the RSNA meeting Monday. Three-D MRA also provides reliable follow-up after treatment.

German researchers pitched real-time contrast-enhanced MR-based subtraction angiography at 3T against conventional DSA to diagnose arteriovenous malformations and fistulae. Principal investigator Dr. Winfried A. Willinek and colleagues at the University of Bonn enrolled 26 prospective patients who underwent gadolinium-enhanced parallel imaging and DSA studies of the brain and feet. Two radiologists reviewed the results in consensus.

The investigators found the dynamic 4D MR subtraction angiography technique to be a reliable, noninvasive alternative to DSA. They were able to follow the dynamic course of the contrast agent in 100% of patients. They were also able to diagnose AVMs and abnormal vascular connections in more than 80% of cases. Four-D MRA matched DSA capabilities in correctly identifying all major feeding arteries as well as deep and superficial venous drainages.

"Four-D MR-DSA at 3T is a promising technique that can compete against conventional DSA. However, DSA is still better than MRA at identifying small arterial feeders," Willinek said.

A study by French investigators validated previous claims about 3D MRA capabilities for the detection of intracranial vascular malformations. Dr. Mina Petkova and colleagues combined time-resolved contrast-enhanced MR-based subtraction angriography with parallel imaging in 43 consecutive patients and compared results against DSA. They found that adding the time-resolved feature enhanced parallel processing and provided results similar to x-ray DSA.

"Three-D MR-DSA can be employed as a reliable and less invasive dynamic angiographic tool for diagnosis and follow-up of intracranial vascular malformations," Petkova said.

Italian investigators assessed the capabilities of 3D MR at 3T for the monitoring of patients undergoing coiling of brain aneurysms. Dr. Nicoletta Anzalone and colleagues at the University of Milan compared standard and angiographic time-of-flight MRI with contrast-enhanced MRA at 1.5T. They found both techniques worked for treatment follow-up, though with some considerations.

"Three-D MRA follow-up of coiled aneurysms at 3T is feasible and better than at 1.5T. However, ultrafast contrast-enhanced MRA at 1.5T provides greater definition of residual patency," Anzalone said.