Ex-vivo MRI provides images at essentially the same time as histological examination of the tissue, and, therefore, allows linking MRI signals to neuropathology findings. Although long scan times are feasible in ex-vivo MRI (generating higher spatial resolution and/or signal to noise ratio compared to in-vivo imaging), we have chosen to collect ex-vivo MRI data with in-vivo-like image properties to facilitate translation. Using this approach, we have developed a unique large database including longitudinal clinical, in-vivo MRI, ex-vivo MRI and neuropathology data on the same persons, and have demonstrated how to perform translational ex-vivo brain MRI.
- We have demonstrated how brain T2 values change with time postmortem.
- We have shown that T2 constants measured ex-vivo are linearly related to T2 constants measured in-vivo.
- We have established that hippocampal volume measured ex-vivo is related to multiple cognitive abilities assessed proximate to death, with its strongest association with episodic memory.
- We have demonstrated that regional brain volumes remain relatively unchanged across time postmortem, at least for the first 6 months after death.
- We have found a close linear correspondence between in-vivo and ex-vivo regional brain volume measurements.
- We have shown that ex-vivo magnetic susceptibility does not change systematically over time postmortem, and that, gray matter susceptibility measured ex-vivo may be well modeled as a linear function of susceptibility measured in-vivo.