T1-weighted parenchyma attenuated inversion recovery: A novel sequence that improves contrast ratio of enhancing brain lesions.

PURPOSE: The purpose of this study was to develop and test a parenchyma attenuated T1-weighted inversion recovery MR sequence (PAIR) that increases the contrast between enhancing and non-enhancing tissues in the brain and to compare the contrast ratio of enhancing brain tumors on this sequence compared to spin echo magnetization transfer (SEMT).

PATIENTS AND METHODS: PAIR sequence parameters were developed to reduce signal from gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) in a healthy adult volunteer. Forty-one patients (17 men and 24 women) with a mean age of 55±13 (SD) years (range: 21-78years) with known or suspected brain tumors underwent PAIR and SEMT imaging after intravenous administration of gadobenate dimeglumine. In patients with confirmed tumors, PAIR and SEMT images were compared for contrast ratio of tumor-to-WM, tumor-to-GM, and tumor-to-CSF.

RESULTS: A total of 23 enhancing neoplastic lesions were found in 14/41 patients. All tumors were visualized on both contrast enhanced PAIR and SEMT images. PAIR images showed a 2.5 fold increase in maximum tumor-to-GM contrast ratio (P<0.0001), a 1.4 fold increase in maximum tumor-to-WM contrast ratio (P=0.0007) and a 5-fold increase in maximum tumor-to-CSF contrast ratio (P<0.0001).

CONCLUSION: PAIR provides improved lesion-to-background contrast ratio compared to SEMT and may be useful as an added sequence in tumor evaluation.