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Reliability of in vivo volume measures of hippocampus and other brain structures using MRI
1Research Service, VA Medical Center West Los Angeles (Brentwood Division), CA 90073.
Abstract:
Volume reductions of the hippocampus are associated with Alzheimer's disease, schizophrenia, and epilepsy. We used clinically available MRI methods (2D acquisition; inversion recovery and calculated T2 images; 3 mm contiguous slices) that optimize image contrast, quality, and resolution and standardized positioning protocols to maximize the in vivo accuracy (test-retest reliability) of brain volume measurements in volunteers who were scanned two or three times. Volunteers were scanned in the same MRI instrument (intrascanner reliability) as well as in two different instruments (interscanner reliability). A single rater obtained brain volume measures of seven contiguous slices centered on the anterior commissure. The in vivo intrascanner reliability for measures of anterior hippocampus and ventricular volumes was very good, with reliability coefficients [intraclass r (rxx)] ranging between .855 and .997, and a median coefficient of variation (CV) of 6.4%. Reliability was good for amygdala (rxx of .740 and .764) and for total frontal and temporal lobe volumes and white matter volume measures (rxx ranging between .640 and .823, median coefficient of variation was 3.2%). Overall, interscanner reliability was also good. We discuss the implications of our results relative to the possible clinical utility of hippocampal quantification and the feasibility of prospective studies aimed at quantifying progressive neurodegeneration.
Insights
Accurate in vivo brain volume measurements, including the hippocampus, are reliable using standard MRI. This supports the clinical use of MRI for tracking neurodegeneration in conditions like Alzheimer's disease.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- Hippocampal volume reduction is linked to Alzheimer's disease, schizophrenia, and epilepsy.
- Accurate in vivo brain volume measurement is crucial for clinical diagnosis and research.
Purpose of the Study:
- To assess the in vivo accuracy and reliability of brain volume measurements using standard MRI techniques.
- To evaluate both intrascanner and interscanner reliability for hippocampal and other brain region volumes.
Main Methods:
- Utilized clinically available 2D MRI acquisition with inversion recovery and calculated T2 images.
- Employed standardized positioning protocols and contiguous 3 mm slices for consistent measurements.
- A single rater quantified brain volumes from seven contiguous slices centered on the anterior commissure.
Main Results:
- Very good intrascanner reliability (intraclass r [rxx] .855–.997) for anterior hippocampus and ventricular volumes (median CV 6.4%).
- Good reliability (rxx .640–.823) for amygdala, frontal/temporal lobes, and white matter volumes (median CV 3.2%).
- Overall good interscanner reliability was also achieved.
Conclusions:
- Standardized MRI protocols provide reliable in vivo measurements of brain volumes, including the hippocampus.
- These findings support the clinical utility of hippocampal quantification for diagnosing and monitoring neurodegenerative diseases.
- The demonstrated reliability facilitates prospective studies on progressive neurodegeneration.