Evaluating CT Perfusion Deficits in Global Cerebral Edema after Aneurysmal Subarachnoid Hemorrhage

Abstract

BACKGROUND AND PURPOSE Global cerebral edema is an independent predictor of mortality and poor outcomes after aneurysmal SAH. Global cerebral edema, a complex disease process, is thought to be associated with an altered cerebral autoregulatory response. We studied the association between cerebral hemodynamics and early global cerebral edema by using CTP. MATERIALS AND METHODS We retrospectively studied consecutive patients with aneurysmal SAH with admission CTP performed at days 0–3. Two neuroradiologists classified global cerebral edema and hydrocephalus on NCCT performed concurrently with CTP. Global cerebral edema was defined as diffuse effacement of the sulci and/or basal cisterns or diffuse disruption of the cerebral gray-white matter junction. CTP was postprocessed into CBF and MTT maps by using a standardized method. Quantitative analysis of CTP was performed by using standard protocol with ROI sampling of the cerebral cortex. The Fisher exact test, Mann-Whitney test, and independent-samples t test were used to determine statistical associations. RESULTS Of the 45 patients included, 42% (19/45) had global cerebral edema and 58% (26/45) did not. Patient groups with and without global cerebral edema were well-matched for demographic and clinical data. Patients with global cerebral edema were more likely to have qualitative global CTP deficits than those without global cerebral edema (P = .001) with an OR = 13.3 (95% CI, 2.09–138.63). Patients with global cerebral edema also had a very strong trend toward statistical significance, with reduced quantitative CBF compared with patients without global cerebral edema (P = .064). CONCLUSIONS Global perfusion deficits are significantly associated with global cerebral edema in the early phase after aneurysmal SAH, supporting the theory that hemodynamic disturbances occur in global cerebral edema.

Application of Blood-Brain Barrier Permeability Imaging in Global Cerebral Edema

“…Furthermore, our findings also demonstrated significantly decreased Ktrans and blood flow (F) in patients with GCE. In the literature, cerebral blood flow (CBF) impairment has been recently reported in patients with GCE 12 . Our data demonstrated decreased CBF in patients with GCE compared to Non-GCE and is thus concordant with previously published studies 12 .…”

“…In the literature, cerebral blood flow (CBF) impairment has been recently reported in patients with GCE 12 . Our data demonstrated decreased CBF in patients with GCE compared to Non-GCE and is thus concordant with previously published studies 12 . Since the derivation of Ktrans is dependent on blood flow, it is a less reliable parameter in flow-restricted conditions, such as seen in GCE 17 .…”

“…Since the derivation of Ktrans is dependent on blood flow, it is a less reliable parameter in flow-restricted conditions, such as seen in GCE 17 . Given that Kep is independent of blood flow, it may represent a more useful parameter to assess BBBP in the context of GCE, particularly when flow impairment occurs 12 . These findings further contribute to our understanding of developing an imaging biomarker of BBBP in flow-restricted conditions such as cerebral edema.…”

“…Up to 24 ROIs were included in each CTP section distributed in the following territories: approximately 4 ROIs in the anterior cerebral artery, 12 in the middle cerebral artery, and 4 in the posterior cerebral artery territories. ROIs overlying large cortical vessels with CBF greater than 100 ml/100 g/min were excluded from the statistical analysis 12 . Mean values, and 95% confidence intervals, were calculated using the remaining ROIs in all CTP sections for each patient.…”

“…However, according to the Lawrence and Lee Model derivations above, decreasing Kep most accurately reflects increasing disruption and permeability of BBB, especially in the setting of impaired cerebral blood flow, such as occurs in GCE 12 .…”