Corrigendum (correction) for Case A-2643
The case report published in the March 2014 issue of Cryonics magazine for case A-2643 contains the following two paragraphs. The underlined text is now known to be incorrect and is explained below.
While surgery and perfusion were accomplished without incident, the actual success of perfusion in this case appears negligible. A lack of brain dehydration, as seen in all patients under non-ideal circumstances of death and/or stabilization and transport, suggests that perfusion was significantly impaired. Further evidence from CT scans corroborates this assumption, revealing what is assumed to be significant perfusion impairment, minimal dehydration, and areas of significant pathology.
Further evidence of poor perfusion can be observed when viewing images of Kim’s brain serially using various CLUTs (color scales) to differentiate areas of presumed impairment vs. cryoprotected areas. When viewed serially there appear to be some areas of cortical cryoprotection, though minimal. The entire subcortex appears impaired.
The incorrect conclusion of “negligible” or “minimal” cryoprotection was based upon uncalibrated post-cryopreservation CT scan data, and belief that lack of brain dehydration during cryoprotectant perfusion necessarily implied poor perfusion. Calibration of the CT scan data to a quantitative scale in October, 2015, revealed that although cryoprotection was non-uniform as originally observed, the non-uniformity mostly spanned a range between 50% and 100% of target cryoprotectant concentration. Areas of cortical cryoprotection that had been characterized as “minimal” actually contained near or above 100% target concentration necessary for vitrification.
The concentration-calibrated CT scan of the entire brain of A-2643 is shown below in movie form. Approximately half the brain volume outside the tumor and fluid-filled ventricles appears to have achieved a cryoprotectant concentration near or above that required for vitrification (light purple or orange). The remainder of the brain experienced various degrees of cryoprotected freezing. Only very small volumes appear to have received negligible cryoprotection (pale blue), such as necrotic portions of tumor and vitreous humor of the eyes.
For comparison, the CT scan A-1088 shows the CT density of a brain frozen without cryoprotectant due to circumstances of the case. The grey appearance of the brain is completely different from A-2643. Much of the brain of A-2643 more closely resembles the CT density visible in the CT scan of A-1002, a case in which the dehydrated brain is believed to have vitrified completely.
It’s also notable that there are no inflections in the cryogenic cooling curve (shown below the CT scan on this page) of A-2643. This implies that tissue in contact with the two temperature probes vitrified. (Significant freezing would cause delay and inflection in the cooling curve due to release of latent heat as water froze.)
A high level of cryoprotection without accompanying cerebral dehydration is a surprising finding of this case. This had never been seen before, which led to the initial incorrect interpretation of poor cryoprotection. The absence of dehydration in this case is now presumed due to opening of the blood brain barrier caused by the one hour of warm ischemia that preceded cryoprotectant perfusion. While tumors can also compromise the blood brain barrier, absence of dehydration was not seen in case A-1097, in which a brain tumor was also present, but no significant interval of warm ischemia occurred.
CT scan of A-2643:
Cryogenic Cooling Curve of A-2643: