Magnetization transfer contrast MR in lesions of the head and neck

To compare lesion-to-background contrast with and without magnetization transfer (MT) in lesions of the head and neck.

Twenty lesions (16 malignant, 4 benign) were evaluated in 17 patients (11 men, 6 women; mean age, 58 years; age range, 39-76 years). In 13 patients, MR imaging was performed at 0.1 T with continuous-wave, off-resonance MT; in 4 patients, MR imaging was performed at 1.5 T with on-resonance, binomial MT prepulses. Fifteen sequences were conducted before the administration of gadopentetate dimeglumine; 13 were conducted after the administration of that contrast material. The ratio of signal intensity with the MT pulses (Ms) to signal intensity without the MT pulses (Mo) was calculated, as were the lesion-to-background contrast and the contrast-to-noise ratios.

Ms/Mo showed both wide variability and considerable overlap among different lesion types. Images from MT sequences showed better contrast than those from non-MT sequences in 23 of 28 lesions (12 of 15 before and 11 of 13 after the administration of contrast material). The mean contrast improvement percentages (+/- standard deviation) were 165.5% (+/- 58%) on unenhanced images and 186.6% (+/- 84.8%) on contrast-enhanced images. The mean improvements in contrast-to-noise ratios were 156% (+/- 60%) on unenhanced images and 171.6% (+/- 98.1%) on contrast-enhanced images.

MT improved contrast between nodes or tumors showing an MT effect and background tissue (usually fat) not showing an MT effect. MT also improved contrast between contrast-enhanced neoplastic lesions and background tissue that showed an MT effect.