Centrifugal Distribution of Regional Cerebral Blood Flow and its Time Course in Traumatic Intracerebral Hematomas

Abstract

Cerebral blood flow (CBF) alterations following post-traumatic contusions have been demonstrated in recent papers. We evaluated regional CBF (rCBF) by means of Xenon-enhanced computerized tomography (Xe-CT) in 29 traumatic intracerebral hematomas, from 22 patients with severe head injury (GCS < or = 8). Fifty traumatic hematoma/Xe-CT CBF measurements were obtained from 39 Xe-CT studies performed during the acute phase (corresponding to the first 20 days post-injury). The rCBF was measured in three different regions of interest: the hemorrhagic core, the perihematoma edematous low-density area, and a 1-cm rim of perihematoma normal-appearing brain tissue, surrounding the edematous low-density area. We found a centrifugal improvement of rCBF as well as a decrease in the rates of CBF levels below 18 mL/100 g/min from the core to the periphery (p < 0.0001), which persisted over time. Ischemic rCBF values were detected in the perihematoma low-density area only in 24% of the traumatic hematomas. The time course of rCBF levels showed a reduced flow in the first 24 h, with a recovery of flow from day 2 to day 4, followed by another reduced flow (p < or = 0.0001) both in the perihematoma edematous low-density area and in the non-lesioned tissue. Our findings suggest that the only area with persistent ischemic values was the hemorrhagic core. Low rCBF levels seen in the perihematoma low-density area may only be ascribed partially to ischemia and can possibly recover over time. These results could encourage a surgical approach based on an early evacuation of the hemorrhagic core associated to a preservation of the surrounding edematous tissue.

A Practical Approach to Interpretation of CBF Measured by Mean of Xenon-CT in Patients with Traumatic Brain Injury

“…(23) describes the time course of global CBF in 522 studies (unpublished data). A similar time course of rCBF has been observed in traumatic contusion by means of intravenous 133 Xenon [79], in traumatic intra-parenchymal hematoma [75] and in the cortex below the evacuated SDH by means of Xe-CT [44]. Although this pattern has been described in pooled patients with TBI it seems to characterize only patients with unfavorable outcome as shown in two studies in which data were dichotomized for favourable and unfavourable outcome [44,76].…”

“…Several studies have evaluated the time course of CBF after injury and converging findings suggest that, in the first hours post injury (phase 1), global CBF is markedly reduced, increases then during days 2-4 (phase 2) and thereafter decreases toward levels higher than those observed in the first 24 hours (phase 3), both in adults [72][73][74][75][76] and in children [77,78]. Fig.…”

Regional Cerebral Blood Flow Using Quantitative MR Angiography

“…In addition, diseases like Moyamoya may be problematic to evaluate, because large vessels are typically replaced by multiple intracranial and extracranial collateral vessels that may not be amenable to flow measurement and would not be accounted for by the partitioning model. For the patient with an extracranial circulation-intracranial circulation bypass, 28 the bypass flow must be measured and included in the regional flow calculation. Last, the number of subjects in each age group was small, especially in the oldest age group.…”

Common data elements in radiologic imaging of traumatic brain injury

“…While CTP affords only a ''snapshot'' view of brain perfusion, continuous ICP monitoring and CPP calculation are possible. On the other hand, in case of aggressive management, MAP and ICP can be almost normalized, but without normalization of brain perfusion (81). In such cases, CPP would be inappropriately normal, but one can expect that CTP would be abnormal.…”

“…Focal perfusion abnormalities are typically observed in and around contusions, even before they become apparent on structural imaging (63)(64)(65). Perfusion, measured using Xenon-enhanced computed tomography (Xe-CT) (80)(81)(82)(83), CTP (63), and DSC-MRI (82)(83)(84), are altered in peri-contusional edematous regions, suggesting ongoing ischemic damage, and a role for perfusion imaging in prognosis (63,85). Focal brain perfusion abnormalities associated with extra-axial blood collections correlate with symptomatology.…”