230.1: Computed tomographic perfusion (CTP) is a useful adjunct to computed tomographic angiography (CTA) in the diagnosis after brain death (BD).

Background: Computed tomographic angiography (CTA) is a new ancillary test used during the brain death (BD) diagnostic procedures. According to 4-point score lack of opacification of cortical segments of both middle cerebral arteries and both internal cerebral veins confirms cessation of brain blood flow. This 4-point grading system was proposed by Leclerc et al. in 2006 [1]. In some cases, especially in the presence of craniectomies or open skull fractures, in patients fulfilling clinical BD criteria, opacification of higher segments of cerebral arteries and/or cerebral veins can be noted. This may be the reason of diagnostic confusion. Sensitivity of CTA in recent publications varies between 85% and 96% [2]. Cerebral circulatory arrest commences at the capillary level, and therefore we hypothesized that computed tomographic perfusion (CTP) would be a more sensitive test than CTA. Aim of the study: The aim of the study was the comparison the sensitivities of CTP and CTA in the diagnosis of BD. Methods: Whole brain CTP was performed in BD patients after completing BD diagnosis. CTA was derived from CTP datasets. Cerebral blood flow (CBF) and volume (CBV) were calculated in 1-cm2 circular regions of interest (ROIs) circumscribing the brainstem, including the midbrain (n = 2), pons (2), and medulla oblongata (2) as well as the cerebellum (8), cortical regions of the frontal (12), parietal (12), temporal (12), and occipital lobes (8), and the basal ganglia (8) drawn bilaterally and placed on each 10-mm axial slice. This resulted in a total of 66 ROIs for each patient (Fig. 1). Results: The CTP findings were interpreted as being consistent with a diagnosis of BD (positive) when CBF and CBV in all ROIs were below 10 mL/100g/min and 1.0 mL/100g, respectively. These thresholds were determined by Astrup et al. in 1981 [3]. The CTA findings were interpreted as consistent with a BD diagnosis (i.e., positive) if the exam revealed bilateral nonfilling of cortical segments of the MCA and bilateral nonfilling of the ICV (Fig. 2). Results: Fifty BD patients were included. The CTP results revealed CBF from 0.00 to 9.98 mL/100g/min (mean, 1.98±1.68 mL/100g/min) and CBV from 0.00 to 0.99 mL/100g (mean, 0.14±0.12mL/100g) and were thus interpreted as positive in all 50 patients. By contrast, the CTA results suggested 7 negative cases, providing a sensitivity of 86%. The difference between the CTP and CTA sensitivity results for the diagnosis of BD was statistically significant (p=0.006). Following the results of our study we implemented CTA and CTP in to the panel of instrumental ancillary tests in currently reviewed Polish BD diagnosis guidelines. Conclusions: CTP performed in combination with CTA in cases when CTA results are negative for BD could increase the sensitivity of CTA. References: 1. Leclerc X. et al. The role of spiral CT for the assessment of the intracranial circulation in suspected brain-death. J Neuroradiol 2006; 33: 90–95 2. Taylor T, et al: Computed tomography (ct) angiography for confirmation of the clinical diagnosis of brain death. Cochrane Database Syst Rev, 2014; 3 Cd009694 3. Astrup J, et al: Thresholds in cerebral ischemia - the ischemic penumbra. Stroke. 1981;12(6):723-5.