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The association between a quantitative computed tomography (CT) measurement of cerebral edema and outcomes in post-cardiac arrest-a validation study.

ABSTRACT: Previous studies have examined the association between quantitative head computed tomography (CT) measures of cerebral edema and patient outcomes reporting that a calculated gray matter to white matter attenuation ratio (GWR) of <1.2 indicates a near 100% non-survivable injury post-cardiac arrest. The objective of the current study was to validate whether a GWR <1.2 reliably indicates poor survival post-cardiac arrest. We also sought to determine the inter-rater variability among reviewers, and examine the utility of a novel GWR measurement to facilitate easier practical use.We performed a retrospective analysis of post-cardiac arrest patients admitted to a single center from 2008 to 2012. Inclusion criteria were age ?18 years, non-traumatic arrest, and available CT imaging within 24h after ROSC. Three independent physician reviewers from different specialties measured CT attenuation of pre-specified gray and white matter areas for GWR calculations.Out of 171 consecutive patients, 90 met the study inclusion criteria. Thirteen patients were excluded for technical reasons and/or significant additional pathology, leaving 77 head CT scans for evaluation. Median age was 66 years and 64% were male. In-hospital mortality was 65% and 70% of patients received therapeutic hypothermia. For the validation measurement, the intra-class correlation coefficient was 0.70. In our dataset, a GWR below 1.2 did not accurately predict mortality or poor neurological outcome (sensitivity 0.56-0.62 and specificity 0.63-0.81). A score below 1.1 predicted a near 100% mortality but was not a sensitive metric (sensitivity 0.14-0.20 and specificity 0.96-1.00). Similar results were found for the exploratory model.A GWR <1.2 on CT imaging within 24h after cardiac arrest was moderately specific for poor neurologic outcome and mortality. Based on our data, a threshold GWR <1.1 may be a safer cut-off to identify patients with low chance of survival and good neurological outcome. Intra-class correlation among reviewers was moderately good.

SUBMITTER: Cristia C

PROVIDER: S-EPMC4172369 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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The association between a quantitative computed tomography (CT) measurement of cerebral edema and outcomes in post-cardiac arrest-a validation study.

Cristia Cristal C Ho Mai-Lan ML Levy Sean S Andersen Lars W LW Perman Sarah M SM Giberson Tyler T Salciccioli Justin D JD Saindon Brian Z BZ Cocchi Michael N MN Donnino Michael W MW

Resuscitation 20140602 10

<h4>Aim</h4>Previous studies have examined the association between quantitative head computed tomography (CT) measures of cerebral edema and patient outcomes reporting that a calculated gray matter to white matter attenuation ratio (GWR) of <1.2 indicates a near 100% non-survivable injury post-cardiac arrest. The objective of the current study was to validate whether a GWR <1.2 reliably indicates poor survival post-cardiac arrest. We also sought to determine the inter-rater variability among rev ...[more]

PMID: 24892267

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Project description:IntroductionMalignant cerebral edema develops in a small subset of patients with hemispheric strokes, precipitating deterioration and death if decompressive hemicraniectomy (DHC) is not performed in a timely manner. Predicting which stroke patients will develop malignant edema is imprecise based on clinical data alone. Head computed tomography (CT) imaging is often performed at baseline and 24-h. We determined the incremental value of incorporating imaging-derived features from serial CTs to enhance prediction of malignant edema.MethodsWe identified hemispheric stroke patients at three sites with NIHSS ≥ 7 who had baseline as well as 24-h clinical and CT imaging data. We extracted quantitative imaging features from baseline and follow-up CTs, including CSF volume, intracranial reserve (CSF/cranial volume), as well as midline shift (MLS) and infarct-related hypodensity volume. Potentially lethal malignant edema was defined as requiring DHC or dying with MLS over 5-mm. We built machine-learning models using logistic regression first with baseline data and then adding 24-h data including reduction in CSF volume (ΔCSF). Model performance was evaluated with cross-validation using metrics of recall (sensitivity), precision (predictive value), as well as area under receiver-operating-characteristic and precision-recall curves (AUROC, AUPRC).ResultsTwenty of 361 patients (6%) died or underwent DHC. Baseline clinical variables alone had recall of 60% with low precision (7%), AUROC 0.59, AUPRC 0.15. Adding baseline intracranial reserve improved recall to 80% and AUROC to 0.82 but precision remained only 16% (AUPRC 0.28). Incorporating ΔCSF improved AUPRC to 0.53 (AUROC 0.91) while all imaging features further improved prediction (recall 90%, precision 38%, AUROC 0.96, AUPRC 0.66).ConclusionIncorporating quantitative CT-based imaging features from baseline and 24-h CT enhances identification of patients with malignant edema needing DHC. Further refinements and external validation of such imaging-based machine-learning models are required.

Project description:Studies of soft tissue composition using computed tomography (CT) scans are often semi-quantitative and based on Hounsfield units (HU) measurements that have not been calibrated with a quantitative CT (QCT) phantom. We describe a study to establish the water (H2O) and dipotassium hydrogen phosphate (K2HPO4) basis set equivalent densities of fat and fat-free liver tissue. With this information liver fat can be accurately measured from any abdominal CT scan calibrated with a suitable phantom.Liver fat content was measured by comparing single-energy QCT (SEQCT) HU measurements of the liver with predicted HU values for fat and fat-free liver tissue calculated from their H2O and K2HPO4 equivalent densities and calibration data from a QCT phantom. The equivalent densities of fat were derived from a listing of its constituent fatty acids, and those of fat-free liver tissue from a dual-energy QCT (DEQCT) study performed in 14 healthy Chinese subjects. This information was used to calculate liver fat from abdominal SEQCT scans performed in a further 541 healthy Chinese subjects (mean age 62 years; range, 31-95 years) enrolled in the Prospective Urban Rural Epidemiology (PURE) Study.The equivalent densities of fat were 941.75 mg/cm3 H2O and -43.72 mg/cm3 K2HPO4, and for fat-free liver tissue 1,040.13 mg/cm3 H2O and 21.34 mg/cm3 K2HPO4. Liver fat in the 14 subjects in the DEQCT study varied from 0-17.9% [median: 4.5%; interquartile range (IQR): 3.0-7.9%]. Liver fat in the 541 PURE study subjects varied from -0.3-29.9% (median: 4.9%; IQR: 3.4-6.9%).We have established H2O and K2HPO4 equivalent densities for fat and fat-free liver tissue that allow a measurement of liver fat to be obtained from any abdominal CT scan acquired with a QCT phantom. Although radiation dose considerations preclude the routine use of QCT to measure liver fat, the method described here facilitates its measurement in patients having CT scans performed for other purposes. Further studies comparing the results with magnetic resonance (MR) measurements of liver fat are required to validate the method as a useful clinical tool.

Dataset Information

The association between a quantitative computed tomography (CT) measurement of cerebral edema and outcomes in post-cardiac arrest-a validation study.

Publications

The association between a quantitative computed tomography (CT) measurement of cerebral edema and outcomes in post-cardiac arrest-a validation study.

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