Understanding drives progress.
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Longitudinal analysis compares two or more MRI brain scans to measure the change over time between each MRI scan. We match both the age and sex of each patient with a group of control subjects to ensure that each patient is properly compared to a group of healthy control subjects. Longitudinal data often shows brain abnormalities that multiple cross-sectional analyses do not reflect.
What is Longitudinal Analysis?
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NeuroGage Longitudinal Analysis method uses comparisons with normal control subjects. Each normal control had 2 MRI scans done. The normal changes in brain volume were calculated.
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In order to perform Longitudinal Analysis on a given patient, the patient will have MRI scans done at two points in time--for example, a year apart--and a brain volume analysis will be done for each. The changes in volume of the brain and brain subregions will be calculated using the same methods that were used for the normal controls. For each brain region, the patient’s annualized percentage change in brain volume will be compared to that of the normal control group in order to determine if the patient's brain volume changed abnormally fast.
What is a Biomarker?
The NeuroGage Traumatic Brain Injury (TBI) Biomarker test was based on NeuroQuant 3.0 volume data and NeuroGage 3.0 asymmetry data. 61 patients with chronic mild or moderate TBI were compared to the normal controls. Neural network analyses, an AI-based method, were used to predict whether each subject belonged to the group of normal controls or patients. The final method was highly accurate for distinguishing patients from normal controls, as shown in the table below:
Since the development of the TBI Biomarker test, we have tested its validity in an additional sample of patients with chronic mild or moderate TBI, many of whom had brain disorders other than TBI. Of that sample (N=47), 93.6% tested positive for a diagnosis of TBI, confirming very good sensitivity of the test. For a subgroup of that sample that included patients with mild TBI but not moderate TBI (N=34), 97.1% tested positive for a diagnosis of TBI, again confirming excellent sensitivity of the test.