Cerebral relaxation times from postmortem MR imaging of adults

We measured T1 and T2 values of cerebral postmortem magnetic resonance (PMMR) imaging and compared the data of cadavers with that of living human subjects.

We performed PMMR imaging of the brains of 30 adults (22 men, 8 women; mean age, 58.2 years) whose deaths were for reasons other than brain injury or disease at a mean of 29.4 hours after death. Before imaging, the bodies were kept in cold storage at 4°C (mean rectal temperature, 15.6°C). We measured T1 and T2 values in the brain bilaterally at 5 sites (bilateral caudate nucleus, putamen, thalamus and gray matter and white matter of the frontal lobe) and compared the data of PMMR imaging with that from MR imaging of the corresponding sites in 24 healthy volunteers (9 men, 15 women; mean age, 51.8 years). We also investigated the influence of body temperature on T1 and T2 values.

Compared with MR imaging findings in the living subjects, PMMR imaging showed significantly shorter T1 values in the caudate nucleus, putamen, thalamus and gray matter and white matter of the frontal lobe and significantly longer T2 values in the gray matter and white matter of the frontal lobe; T2 values in the caudate nucleus, putamen, and thalamus showed no such differences. T1 values correlated significantly with body temperature in all 5 brain sites measured, but T2 values did not.

Compared with findings of cerebral MR imaging in living adult subjects, those of PMMR imaging tended to demonstrate shorter T1 values and longer T2 values. We attribute this to increased water content of tissue, reduced pH, and reduced body temperature after death.