Implementation of Computed Tomography Angiography (CTA) and Computed Tomography Perfusion (CTP) in Polish Guidelines for Determination of Cerebral Circulatory Arrest (CCA) during Brain Death/Death by Neurological Criteria (BD/DNC) Diagnosis Procedure

Abstract

Background: Brain death/death by neurologic criteria (BD/DNC) guidelines are routinely analyzed, compared and updated in the majority of countries and are later implemented as national criteria. At the same time, extensive works have been conducted in order to unify clinical procedures and to validate and implement new technologies into a panel of ancillary tests. Recently evaluated computed tomography angiography and computed tomography perfusion (CTA/CTP) seem to be superior to traditionally used digital subtraction angiography (DSA), transcranial Doppler (TCD) and cerebral perfusion scintigraphy for diagnosis of cerebral circulatory arrest (CCA). In this narrative review, we would like to demonstrate scientific evidence supporting the implementation of CTA/CTP in Polish guidelines for BD/DNC diagnosis. Research and implementation process: In the first of our base studies concerning the potential usefulness of CTA/CTP for the confirmation of CCA during BD/DNC diagnosis procedures, we showed a sensitivity of 96.3% of CTA in a group of 82 patients. CTA was validated against DSA in this report. In the second study, CTA showed a sensitivity of 86% and CTP showed a sensitivity of 100% in a group of 50 patients. In this study, CTA and CTP were validated against clinical diagnosis of BD/DNC supported by TCD. Additionally, we propose our CCA criteria for CTP test, which are based on ascertainment of cerebral blood flow (CBF) < 10 mL/100 g/min and cerebral blood volume < 1 mL/100 g in regions of interest (ROIs) localized in all brain regions. Based on our research results, CTA/CTP methods were implemented in Polish BD/DNC criteria. To our knowledge, CTP was implemented for the first time in national guidelines.

Conclusions: CTA and CTP-derived CTA might be in future the tests of choice for CCA diagnosis, proper and/or Doppler pretest might significantly increase sensitivity of CTA in CCA diagnosis procedures. Whole brain CTP might be decisive in some cases of inconclusive CTA. Implementation of CTA/CTP in the Polish BD/DNC diagnosis guidelines does not show any major obstacles. We believe that in next edition of "The World Brain Death Project" CTA and CTP will be recommended as ancillary tests of choice for CCA confirmation during BD/DNC diagnosis procedures.

Keywords: CT angiography; CT perfusion; brain death; cerebral blood flow; death by neurologic criteria.

Figure 1

Various scales used for CCA diagnosis in CTA imaging: (A) 10-point scale, where positive result (score = 10) confirming CCA is stated when bilateral ACA-A3, MCA-M4, PCA-P2 and ICV and single GCV and BA are not opacified; (B) 7-point scale, where positive result (score = 7) confirming CCA is stated when bilateral ACA-A3, MCA-M4 and ICV and single GCV are not opacified; (C) 4-point scale, where positive result (score = 4) confirming CCA is stated when bilateral MCA-M4 and ICV are not opacified.

Figure 2

Criteria of CCA in CTP imaging. Axial sections of brain with marked positions of ROIs. Color scale illustrates range of CBF (mL/100 g/min). CBF < 10 mL/100 g/min confirms CCA.

Figure 3

Different CTA (upper row) and CTP (lower row) patterns during CCA diagnosis procedures: (A) patient with suspected ischemic stroke with normal CTA and CTP; (B) patient with opacification limited to proximal segments of middle cerebral arteries MCA-M1 inCTA (red arrows) and CBF value < 10 mL/100 g/min in CTP; both techniques confirm CCA. (C) Patient with bilateral opacification of cortical arterial segments (MCA-M4; red arrows) in CTA, not consistent with CCA diagnosis and CBF value < 10 mL/100 g/min in CTP, which confirms CCA diagnosis; (D) patient with opacified MCA-M4 segments (red arrows) and opacified internal cerebral vein (blue arrow) in CTA, not consistent with CCA diagnosis and CBF value < 10 mL/100 g/min, which confirms CCA diagnosis; (E) patient with opacified MCA-M2/M3 segments (red arrows) in CTA, consistent with CCA diagnosis and isolated single sub-craniectomy area with CBF value > 10 mL/100 g/min (white arrow), also consistent with CCA diagnosis; (F) patient with opacified MCA-M4 segments (red arrows) and opacified internal cerebral vein (blue arrow) in CTA, not consistent with CCA diagnosis and multiple scattered areas with CBF value > 10 mL/100 g/min (white arrows), also inconsistent with CCA diagnosis. Color scales illustrate range of CBF (mL/100 g/min). CBF < 10 mL/100 g/min confirms CCA.

Figure 4

Schematic algorithm of application of CTA and CTP for CCA confirmation according to Polish national guidelines for BD/DNC diagnosis. Notes: * bilateral non-filling of cortical arteries (MCA-M4) and ICVs in late phase with normal filling of extracranial arteries in early phase; filling of one or two cortical arteries on the same side is permissible as long as the ICVs are not filled. ** CBF below 10 mL/100 g/min and CBV below 1.0 mL/100 g in all ROIs. Presence of small, isolated foci with CBF or CBV above these values are permissible in regions of local decompression due to craniectomy or open skull fracture. BD/DNC—brain death/death by neurologic criteria; CCA—cerebral circulatory arrest.