Imaging cadavers: cold FLAIR and noninvasive brain thermometry using CSF diffusion.
There is increasing interest in imaging cadavers for noninvasive autopsies for research purposes. However, the temperature is well below that of in vivo imaging, and a variety of interesting 'cold brain' effects are observed. At lower temperatures conventional FLAIR sequences no longer produce dark cerebrospinal fluid (CSF); T(1) is reduced from about 4.0 sec in vivo to 1.7 sec at 1 degrees C. The diffusion coefficient (DC) of CSF is much reduced (from 3.1 10(-9) m(2)s(-1) in vivo to 1.1 at 1 degrees C). DC values therefore provide a noninvasive thermometer to measure brain core temperature to within 1.0 degrees C. In three cadavers DC values were 1.1-1.5 10(-9) m(2)s(-1), indicating brain core temperatures of 1-10 degrees C, consistent with external thermocouple measurements. An improved inversion time (TI(0)) can then be found for FLAIR. At 10 degrees C this Cold FLAIR sequence (TI(0) = 1.5 sec) gave black CSF. Expressions for CSF DC and T(1) as a function of temperature were produced. A measurement of CSF DC could be converted directly to temperature and the required TI(0) found. In vitro values of CSF DC were about 1% lower than that of water. Thus, FLAIR imaging can be optimized for cadaveric brains at low and unknown temperatures, thereby improving value for autopsy purposes and facilitating comparisons with in vivo imaging.
Institute of Neurology, Queen Square, University College London, UK. p.s.tofts@bsms.ac.uk
Paul S
PS
Tofts
Jonathan S
JS
Jackson
Daniel J
DJ
Tozer
Mara
M
Cercignani
Geoffrey
G
Keir
David G
DG
MacManus
Gerard R
GR
Ridgway
Basil H
BH
Ridha
Klaus
K
Schmierer
Durre
D
Siddique
John S
JS
Thornton
Stephen J
SJ
Wroe
Nick C
NC
Fox
D001344:Autopsy / Q000379:methods*; D001831:Body Temperature; D001921:Brain / Q000473:pathology*; D002102:Cadaver; D002555:Cerebrospinal Fluid; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011180:Postmortem Changes