MT MRI Contrast No Help in Cirrhosis Diagnosis

November 27, 2011

Magnetization transfer (MT) contrast-prepared magnetic resonance imaging is “unlikely to be of clinical utility” in diagnosing cirrhosis, according to a study published online Nov. 23 in the journal Radiology.

Magnetization transfer (MT) contrast-prepared magnetic resonance imaging is “unlikely to be of clinical utility” in diagnosing cirrhosis, according to a study published online Nov. 23 in the journal Radiology.

The study did confirm the ability of MT contrast prepared MRI to help distinguish substances of varying protein concentration, according to New York University researchers led by radiologist Andrew B. Rosenkrantz, MD.

Researchers studied 20 patients with cirrhosis and portal hypertension and 20 healthy volunteers with no known liver disease. Rosenkrantz and colleagues had previously optimized the MT sequence using agar phantoms with protein concentrations ranging from 0 percent to 4 percent. The subjects underwent liver MR imaging that included eight separate breath-hold MT contrast sequences, each performed by using a different MT pulse frequency offset (range, 200–2500 Hz). Regions of interest were then placed to calculate the MT ratio for the liver, fat, and muscle in the volunteer group and for the liver in the cirrhosis group.

The MT ratio was nearly identical between healthy (26.0 percent to 80.0 percent) and cirrhotic livers (26.7 percent to 81.2 percent) for all frequency offsets.

But as has been showed with previous studies, MT ratio can indeed differentiate tissue types. MT ratio increased with decreasing MT pulse frequency offset for each of the four phantoms and the assessed in vivo tissues, consistent with previous reports. At all frequency offsets, MT ratio increased with increasing phantom protein concentration. In volunteers, at frequency offsets greater than 400 Hz, the MT ratio was significantly greater for muscle (34.4 percent to 54.9 percent) and much lower for subcutaneous fat (10.3 percent to 12.6 percent), compared with that for the liver (22.8 percent to 46.9 percent).