Value of Perfusion Computed Tomography (PCT) Imaging After Aneurysmal Subarachnoid Hemorrhage: A Review of the Current Data

Time of PCT

Publication

Patient cohort

Time of scan

Key finding

Early PCT

Tateyama et al. [16]

21 patients

<3 h

Global MTT prolongation is an independent predictor of outcome

Tsuang et al. [17]

38 patients

<6 h

Early bilateral prolonged MTT at the thalami is associated with poor outcome

Etminan et al. [4]

79 patients

<12 h

Subarachnoid clot volume and early MTT prolongation have an amplified risk for DCI and poor outcome

Schubert et al. [15]

17 patients

<12 h

The first 12 h after aSAH are characterized by reduction of CBF independent of ICP or CPP

Honda et al. [6]

94 patients

24–72 h

Higher CBF and lower MTT was found in patients with favorable outcome

Nabavi et al. [11]

15 patients

<48 h

The majority of patients showed changes in CBF and CBV with time suggestive of disturbed autoregulation

Van der Schaaf et al. [19]

45 patients

<72 h

The development of DCI is related to brain perfusion assessed by PCT shortly after aSAH

Sanelli et al. [13]

75 patients

<72 h

CBF reduction and MTT prolongation can be demonstrated early in aSAH patients who later develop vasospasm

Van Asch et al. [18]

138 patients

<72 h

Acute hydrocephalus after aSAH reduces CBF in the deep grey matter and periventricular white matter

Follow-up PCT

Sanelli et al. [14]

97 patients

Day 6–8

CBF and MTT at days 6–8 have the highest diagnostic accuracy for DCI

Pham et al. [12]

38 patients

>3 days, <14 days

Time to peak in PCT is a sensitive and early predictor of secondary cerebral infarction

Dankbaar et al. [2]

42 patients

<3 days to 14 days

CBF and MTT values worsening precedes DCI

Wintermark et al. [22]

27 patients

<3 days to 14 days

MTT represents the most sensitive parameter to detect vasospasm

Kunze et al. [8]

53 patients

>3 days, <14 days

Repeatedly obtained PCT is a valuable tool to detect DCI

Aralasmak et al. [1]

55 patients

Day 3 to day 15

PCT indicates high likelihood of perfusion abnormality in case of macrovascular vasospasm

Moftakhar et al. [10]

14 patients

Day 1–15

High agreement between DSA and PCT for detection of DCI

MTT mean transit time, DCI delayed cerebral ischemia, aSAH aneurismal subarachnoid hemorrhage, CBF cerebral blood flow, ICP intracranial pressure, CPP cerebral perfusion pressure, CBV cerebral blood volume, DSA digital subtraction angiography

Summary of Early PCT Data

In the first 72 h after aSAH, the majority of patients demonstrated changes in cerebral blood flow (CBF) and cerebral blood volume (CBV), which suggests an impaired autoregulation [11]. This reduction of CBF may persist over the initial phase after hemorrhage, independent from intracranial pressure and/or cerebral perfusion pressure. Additionally, a strong correlation between impaired global perfusion and clinical presentation at admission was demonstrated using Xenon-enhanced CT imaging [15]. In line with the aforementioned decrease in CBF, a prolongation of mean transit time (MTT) was reported. Early MTT prolongation significantly correlated with early mortality and occurrence of angiographic vasospasm [9]. These findings were confirmed by data reporting an association of prolonged early MTT in the thalami with poor outcome [17]. Moreover, a global MTT prolongation in the first hours after aSAH was reported as an independent predictor for poor outcome [16]. Additionally, we recently reported that the risk for new cerebral infarction and poor outcome is higher in patients with concomitant large subarachnoid clot volumes and ultra-early MTT prolongation, as opposed to sole MTT prolongation. Using a risk model based on these two variables, we defined three different risk groups for outcome prediction [4]. Changes in early cerebral perfusion, as detected by PCT, can be related to the risk for DCI because patients developing DCI show significantly more asymmetry in perfusion between the hemispheres in semiquantitative data sets [19]. An early reduction of CBF and prolongation of MTT within the first 72 h after aSAH was related to the incidence of subsequent DCI [13]. This was also supported by our own data [4]. Correspondingly, patients with favorable outcomes had increased CBF and lower MTT values. Thus, discriminant analysis of these parameters can predict patient outcome with fair probability [6]. Interestingly, early PCT can also show the effect of acute hydrocephalus on the CBF in the periventricular white matter and deep grey matter [18].

Only gold members can continue reading. Log In or Register to continue