Carsten Krautmacher MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: To compare clinical high field MR imaging at 3.0 Tesla with standard imaging at 1.5 Tesla in patients with contrast enhancing brain tumors, to evaluate T1-weighted (T1w) SE, FFE, and MDEFT (modified driven equilibrium Fourier transform) sequences with respect to contrast-to-noise ratio (CNR). Methods and Materials: This was an intra-individual comparative study performed in 12 patients (6 female, 6 male, mean age 58 years), 11 with primary brain tumors and one with brain metastases on 1.5T and 3.0T clinical whole body MR scanners. Imaging protocols included axial T1w SE, T1w FFE, and T1w MDEFT sequences before and after administration of Gd-DTPA (0.1 mmol/kg body weight). Sequence parameters were largely identical at 1.5T and 3.0T: SE (TR=500ms, TE=12ms), FFE (TR=350ms, TE=4.6ms/2.6ms, flip angle=80º/100º at 1.5T/3.0T, respectively), MDEFT (TR=1400ms, TI=700ms, TE=9ms). Geometrical parameters were the same for all sequences: slice thickness/gap=5mm/1mm, field of view=230mmx230mm, matrix=256x206. Interval between consecutive scans at 1.5T and 3.0T was at least 24 hours. CNR was assessed by ROI-analysis of enhancing lesions and contralateral white matter. Results: ROI-based image analysis demonstrated higher contrast-to-noise ratios of enhancing brain tumors for all three T1-weighted sequences at 3.0T. At 3.0T, the different pulse sequences showed a gain in CNR relative to respective sequences at 1.5T as follows (CNR3.0T/CNR1.5T): T1w SE (2.5), T1w FFE (2.0), and T1w MDEFT (2.5). Generally, relative level of CNR was higher for SE sequences than for FFE and MDEFT sequences at 3.0T: 1.0, 0.62, 0.54, respectively. Conclusion: MR imaging of contrast enhancing brain tumors benefits from CNR gain at high field. Of the analyzed T1-weighted pulse sequence types, the SE sequence benefited most from the increase in field strength, and showed highest CNR at 3.0 Tesla.      

Krautmacher MD, C, 3.0 Tesla versus 1.5 Tesla MRI of Contrast Enhancing Brain Tumors: Evaluation of T1-weighted SE, FFE, and MDEFT Sequences.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3102648.html