Whole Brain Volume Measured from 1.5T vs. 3T MRI in Healthy Subjects and Patients with Multiple Sclerosis (P6.156)

OBJECTIVE: Evaluate differences in brain parenchymal volumes (BPVs) from 1.5T vs. 3T in patients with multiple sclerosis (MS) vs. normal controls (NC) and test their relative strength in correlations with MS clinical status (physical disability and cognition). BACKGROUND: Whole brain atrophy is a standard secondary outcome in relapsing-remitting (RR) MS therapeutic trials. With the ongoing MRI transformation from 1.5T to 3T for MS clinical care and research to affect improved scan acquisition time/quality, there is an unmet need to calibrate this change. We compared the clinical relationships between brain parenchymal volumes (BPV) from 1.5T and 3T in patients and normal controls (NC). DESIGN/METHODS: We studied MS patients [n=26, age (mean, range) 43 (21-55), 22 (85[percnt]) RRMS, Expanded Disability Status Scale (EDSS) 1.98 (0-6.5), timed 25 foot walk (T25FW) 5.95 (3.2-33.0 seconds)] and NC [n=9, age 45 (31-53)]. Subjects underwent 1.5T (Phillips) and 3T (GE) brain 3D-T1-weighted scans to derive normalized BPV from an optimized fully automated SIENAX pipeline. The patients underwent cognitive testing of commonly affected domains. RESULTS: BPV-1.5T was higher than BPV-3T [mean (95[percnt] confidence interval) +45.7 mL (+35.3, +56.1), p<0.00001]. This appeared to result from improved tissue-CSF contrast at 3T. BPV-3T showed a larger volume decrease and a larger effect size in detecting brain atrophy in MS vs. NC [-74.5 mL (-126.5, -22.5), p=0.006, d=0.92] vs. BPV-1.5T [-51.3 mL (-99.8, -2.8), p=0.04, d=0.67]. Correlations between BPV-1.5T and EDSS (r=-0.43, p=0.027) and BPV-3T and EDSS (r=-0.49, p=0.011) and between BPV-1.5T and T25FW (r=-0.46, p=0.018) and BPV-3T and T25FW (r=-0.56, p=0.003) slightly favored 3T. BPV-cognition correlations were significant (p<0.05) for 6 of 11 subscales to a similar degree at 1.5T (r range=0.44-0.58) and 3T (r range=0.43-0.53). CONCLUSIONS: Field strength may impact whole brain volume measurements when evaluating patients with MS. Study Supported by: National Multiple Sclerosis Society RG3798A2 (Bakshi) Disclosure: Dr. Chu has nothing to disclose. Dr. Tauhid has nothing to disclose. Dr. Glanz has received research support from Merck Serono. Dr. Healy has received research support from Merck Serono. Dr. Kim has nothing to disclose. Dr. Oommen has nothing to disclose. Dr. Khalid has nothing to disclose. Dr. Neema has nothing to disclose. Dr. Bakshi has received personal compensation for activities with Biogen Idec, Novartis, Sanofi/Genzyme, and Teva Neuroscience as a consultant.