The Role of Neuroimaging in the Determination of Brain Death

Abstract

BACKGROUND AND PURPOSEBrain death determination (BDD) is primarily a clinical diagnosis, where death is defined as the permanent loss of brainstem function. In scenarios where clinical examinations are inaccurate, ancillary imaging tests are required. The choice of ancillary imaging test is variable, but the common denominator for all of them is to establish a lack of cerebral blood flow. The purpose of this study was to compare the diagnostic accuracy and interrater reliability of different ancillary imaging tests used for BDD.METHODSArchival data were retrospectively analyzed for all patients who underwent any ancillary imaging test for BDD at our institution. The results of ancillary imaging tests were compared with, the reference standard, the clinical checklist for declaration of brain death. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of different ancillary imaging tests for BDD were performed. Interobserver agreement between two observers was measured using kappa statistics for each of the imaging modalities.RESULTSA total of 74 patients underwent 41 computer tomography perfusion (CTP), 54 CT angiogram, 15 radionuclide scans, 1 cerebral angiogram, 3 magnetic resonance imaging, and 71 nonenhanced CT (NECT) head for BDD. All ancillary tests (except NECT head) showed 100% specificity and PPV. CTP had the highest sensitivity and NPV. All ancillary imaging tests demonstrated very high interrater reliability.CONCLUSIONSThe uses of ancillary imaging tests for BDD are increasing. Within this study's limitations, CTP followed by radionuclide scan were found to be the most accurate and reliable ancillary imaging test for BDD.

Ancillary Imaging Tests for Confirmation of Brain Death

“…Another recent study from Macdonald et al reported the diagnostic accuracy and inter-rater reliability of different ancillary imaging tests used for brain death in 74 patients. They showed that CTA along with CTP and radionuclide scan had a specificity and positive predictive value of 100% [10]. These results certainly add to the growing medical literature that supports the use of CTA as a reliable ancillary imaging test in confirming the brain death.…”

“…For whole brain CTP, Ancillary Imaging Tests for Confirmation of Brain Death DOI: http://dx.doi.org /10.5772/intechopen.86516 they also showed a sensitivity of 100% to confirm the diagnosis of brain death [24]. MacDonald et al showed similar sensitivity [10].…”

“…Plain head CT does not provide functional information of the brain and does not assess intracranial blood flow. Diffuse loss of gray-white mater differentiation is likely a late phenomenon and the inter-rater reliability is poor [10].…”

“…CTP can also evaluate brain-stem specific CBF [10,20]. The concept of isolated brainstem death was first proposed by Shankar et al in clinically confirmed brain death patients (Figure 6) [20].…”

“…Exact pathophysiological mechanism behind isolated brainstem death is not yet known. This is described when in patients with clinically confirmed brain death, there is presence of blood flow in the supratentorial brain and isolated absence of blood flow in the brainstem [10,20]. Clinical examination does not differentiate between whole brain death and isolated brainstem death.…”