Abstract
The gray-to-white matter ratio (GWR) has been used to identify brain damage in comatose patients after cardiac arrest. However, Hounsfield units (HUs), the measurement of brain density on computed tomography (CT) images, may vary depending on the machine type or parameter. Therefore, differences in CT scanners may affect the GWR in post-cardiac arrest patients. We performed a retrospective study on comatose post-cardiac arrest patients who visited the hospital from 2007 to 2017. Two CT, Lightspeed and SOMATOM, scanners were used. Two observers independently measured the HUs of the caudate nucleus, putamen, posterior internal capsule, and corpus callosum using regions of interest. We compared the GWR calculated from the HUs measured at different CT scanners. The analysis of different scanners showed statistically significant differences in the measured HUs and GWR. The HUs and GWR of Lightspeed were measured lower than SOMATOM. The difference between the two CT scanners was also evident in groups divided by neurological prognosis. The area under the curve of the receiver operating characteristic curve to predict poor outcomes of Lightspeed was 0.798, and the cut-off value for 100% specificity was 1.172. The SOMATOM was 0.855, and the cut-off value was 1.269. The difference in scanners affects measurements and performance characteristics of the GWR in post-cardiac arrest patients. Therefore, when applying the results of the GWR study to clinical practice, reference values for each device should be presented, and an integrated plan should be prepared.
Highlights
Target temperature management (TTM) is commonly applied to patients who remain comatose following resuscitation after cardiac arrest since it has been shown to improve survival and neurological outcomes [1, 2]
The grayto-white matter ratio (GWR), began to be used as a prognostic factor for comatose post-cardiac arrest patients after Torbey et al quantitatively measured the difference between gray matter (GM) and white matter (WM) and has since been studied in various ways by other researchers [3,4,5,6,7,8,9,10]
Forty-three patients were classified into the Lightspeed group, and others were classified into the SOMATOM group (Fig 1)
Summary
Target temperature management (TTM) is commonly applied to patients who remain comatose following resuscitation after cardiac arrest since it has been shown to improve survival and neurological outcomes [1, 2]. Electroencephalogram analysis, serum neuron-specific enolase, somatosensory evoked potentials, brain diffusion magnetic resonance imaging (MRI), and the brainstem response have been presented as prognostic predictors in recent studies [2]. Another prognostic factor, the grayto-white matter ratio (GWR), began to be used as a prognostic factor for comatose post-cardiac arrest patients after Torbey et al quantitatively measured the difference between gray matter (GM) and white matter (WM) and has since been studied in various ways by other researchers [3,4,5,6,7,8,9,10]. The GWR can present patient prognosis prediction criteria by representing qualitative interpretations in quantitative value
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