Parallel imaging: is GRAPPA a useful acquisition tool for MR imaging intended for volumetric brain analysis?

Optimisation studies were performed on a young healthy volunteer and the selected protocol (including the use of two different parallel imaging acceleration factors) was then tested on a cohort of 15 elderly volunteers including MCI and AD patients. In addition to automatic brain segmentation, hippocampus volumes were manually outlined and measured in all patients. The 15 patients were scanned on a second occasion approximately one week later using the same protocol and evaluated in the same manner to test repeatability of measurement using images acquired with the GRAPPA parallel imaging technique applied to the MPRAGE sequence.Intraclass correlation tests show that almost perfect agreement between repeated measurements of both segmented brain parenchyma fraction and regional measurement of hippocampi. The protocol is suitable for both global and regional volumetric measurement dementia patients.In summary, these results indicate that parallel imaging can be used without detrimental effect to brain tissue segmentation and volumetric measurement and should be considered for both clinical and research studies where longitudinal measurements of brain tissue volumes are of interest.Age is the strongest predicting factor for dementia. In total, dementia affects more than 25% of those aged over 85 years and between 30 and 50% of those aged over 90 years. Due to the population boom of the 1940's the elderly population is rapidly growing. Thus, the prevalence of dementia is expected to increase significantly over the coming decades. Rapid diagnosis and treatment is therefore of evermore-importance.One of the most widely accepted imaging biomarkers in the aging process is that of brain tissue atrophy and an increase in cerebral spinal fluid (CSF) volume. Much effort is put into correlating rates of brain atrophy with disease progression [1,2]in order that the imaging may be used as a diagnostic tool [3] rather than depending on mental ability tests only. As yet, there is no