SENSE imaging improves breast MR

Parallel imaging in breast MR improves lesion characterization and significantly reduces scan time, allowing for shorter bilateral examinations, according to researchers at Saint Barnabas Medical Center in Livingston, NJ.

Saint Barnabas is a community hospital where Dr. Paul D. Friedman and colleagues perform about 125 breast MR exams a month. Since January 2002, they have scanned approximately 1300 patients using sensitivity encoded (SENSE) technology.

"To our knowledge, this is the largest ongoing application of SENSE imaging for breast examinations," the researchers wrote in the February issue of the American Journal of Roentgenology.

Before SENSE imaging, unilateral imaging took 30 minutes, required two patient visits, two contrast injections, and subtraction images. Temporal resolution was greater than one minute.

The use of SENSE imaging has resulted in shorter scanning times (22-minute bilateral scans) that, in turn, have improved patient comfort, generated increased patient throughput, and resulted in lower costs, according to the study.

The SENSE technique uses multiple receiver coil elements to encode spatial resolution, thus effectively creating parallel imaging. Parallel imaging brings both higher spatial resolution for morphology and higher temporal resolution for dynamic contrast enhancement. Artifacts from breathing and cardiac motion are significant reduced.

High spatial resolution is essential for better visualization of morphology and the characterization of lesions. High temporal resolution is essential for better contrast uptake statistics and, consequently, for the characterization of lesions, Freidman said.

Image protocol include non-fat-saturated T1-weighted and fat-saturated T2-weighted acquisitions before contrast administration. All the images were acquired in a conventional bilateral fashion in a transverse orientation. Both the T1- and T2-weighted protocols were based on turbo spin-echo protocols with an in-plane resolution of 1 by 1.2 mm, 30 slices of 5-mm thickness, and scanning times of 51 and 42 seconds, respectively.

The 3D dynamic contrast enhancement acquisition was performed in three different orders, with no protocol exceeding five minutes:

• high temporal and low spatial resolution

• moderate temporal and spatial resolution

• low temporal and high spatial resolution

Sensitivity for breast MRI is high, ranging from 94% to 100%. But specificity suffers, with a range of 37% to 97%. Friedman speculated that low specificity may be due, in part, to variations in technique and reviewer interpretation. SENSE imaging can increase specificity by improving technique and aiding in improved characterization of lesions and uptake statistics, he said.

"Breast MRI generally is considered an expensive examination technique with a relatively low specificity. However, with continued improvements in technique aimed at increasing patient throughput, reducing costs, and improving diagnostic specificity, breast MRI will become even more beneficial and, possibly, become an effective screening tool," the authors concluded.

For more information from the Diagnostic Imaging archives:

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