Whole brain quantitative T2 MRI across multiple scanners with dual echo FSE: Applications to AD, MCI, and normal aging

The ability to pool data from multiple MRI scanners is becoming increasingly important with the influx in multi-site research studies. Fast spin echo (FSE) dual spin echo sequences are often chosen for such studies based principally on their short acquisition time and the clinically useful contrasts they provide for assessing gross pathology. The practicality of measuring FSE-T2 relaxation properties has rarely been assessed. Here, FSE-T2 relaxation properties are examined across the three main scanner vendors (General Electric (GE), Philips, and Siemens). The American College of Radiology (ACR) phantom was scanned on four 1.5T platforms (two GE, one Philips, and one Siemens) to determine if the dual echo pulse sequence is susceptible to vendor-based variance. In addition, data from 85 subjects spanning the spectrum of normal aging, mild cognitive impairment (MCI), and Alzheimer's disease (AD) was obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) to affirm the presence of any phantom based between vendor variance and determine the relationship between this variance and disease. FSE-T2 relaxation properties, including peak FSE-T2 and histogram width, were calculated for each phantom and human subject. Direct correspondence was found between the phantom and human subject data. Peak FSE-T2 of Siemens scanners was consistently at least 20ms prolonged compared to GE and Philips. Siemens scanners showed broader FSE-T2 histograms than the other scanners. Greater variance was observed across GE scanners than either Philips or Siemens. FSE-T2 differences were much greater with scanner vendor than between diagnostic groups, as no significant changes in peak FSE-T2 or histogram width between normal aged, MCI, and AD subject groups were observed. These results indicate that whole brain histogram measures are not sensitive enough to detect FSE-T2 changes between normal aging, MCI, and AD and that FSE-T2 is highly variable across scanner vendors.