CT perfusion diagnoses delayed cerebral ischemia in the early stage of the time-window after aneurysmal subarachnoid hemorrhage

CT perfusion imaging in aneurysmal subarachnoid hemorrhage. State of the art

CT perfusion (CTP) images can be easily and rapidly obtained on all modern CT scanners and have become part of the routine imaging protocol of patients with aneurysmal subarachnoid haemorrhage (aSAH). There is a growing body of evidence supporting the use of CTP imaging in these patients, however, there are significant differences in the software packages and methods of analysing CTP. In. addition, no quantitative threshold values for tissue at risk (TAR) have been validated in this patients' population. Here we discuss the contribution of the technique in the identification of patients at risk of aSAH-related delayed cerebral ischemia (DCI) and in the assessment of the response to endovascular rescue therapy (ERT). We also address the limitations and pitfalls of automated CTP postprocessing that are specific to aSAH patients as compared to acute ischemic stroke (AIS).

CTP for the Screening of Vasospasm and Delayed Cerebral Ischemia in Aneurysmal SAH: A Systematic Review and Meta-analysis

BACKGROUND

Delayed cerebral ischemia and vasospasm are the most common causes of late morbidity following aneurysmal SAH, but their diagnosis remains challenging.

PURPOSE

This systematic review and meta-analysis investigated the diagnostic performance of CTP for detection of delayed cerebral ischemia and vasospasm in the setting of aneurysmal SAH.

DATA SOURCES

Studies evaluating the diagnostic performance of CTP in the setting of aneurysmal SAH were searched on the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Cochrane Clinical Answers, Cochrane Methodology Register, Ovid MEDLINE, EMBASE, American College of Physicians Journal Club, Database of Abstracts of Reviews of Effects, Health Technology Assessment, National Health Service Economic Evaluation Database, PubMed, and Google Scholar from their inception to September 2023.

STUDY SELECTION

Thirty studies were included, encompassing 1786 patients with aneurysmal SAH and 2302 CTP studies. Studies were included if they compared the diagnostic accuracy of CTP with a reference standard (clinical or radiologic delayed cerebral ischemia, angiographic spasm) for the detection of delayed cerebral ischemia or vasospasm in patients with aneurysmal SAH. The primary outcome was accuracy for the detection of delayed cerebral ischemia or vasospasm.

DATA ANALYSIS

Bivariate random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio. Subgroup analyses for individual CTP parameters and early-versus-late study timing were performed. Bias and applicability were assessed using the modified QUADAS-2 tool.

DATA SYNTHESIS

For assessment of delayed cerebral ischemia, CTP demonstrated a pooled sensitivity of 82.1% (95% CI, 74.5%-87.8%), specificity of 79.6% (95% CI, 73.0%-84.9%), positive likelihood ratio of 4.01 (95% CI, 2.94-5.47), and negative likelihood ratio of 0.23 (95% CI, 0.12-0.33). For assessment of vasospasm, CTP showed a pooled sensitivity of 85.6% (95% CI, 74.2%-92.5%), specificity of 87.9% (95% CI, 79.2%-93.3%), positive likelihood ratio of 7.10 (95% CI, 3.87-13.04), and negative likelihood ratio of 0.16 (95% CI, 0.09-0.31).

LIMITATIONS

QUADAS-2 assessment identified 12 articles with low risk, 11 with moderate risk, and 7 with a high risk of bias.

CONCLUSIONS

For delayed cerebral ischemia, CTP had a sensitivity of >80%, specificity of >75%, and a low negative likelihood ratio of 0.23. CTP had better performance for the detection of vasospasm, with sensitivity and specificity of >85% and a low negative likelihood ratio of 0.16. Although the accuracy offers the potential for CTP to be used in limited clinical contexts, standardization of CTP techniques and high-quality randomized trials evaluating its impact are required.

CT perfusion-guided administration of IV milrinone is associated with a reduction in delayed cerebral infarction after subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a singular pathological entity necessitating early diagnostic approaches and both prophylactic and curative interventions. This retrospective before-after study investigates the effects of a management strategy integrating perfusion computed tomography (CTP), vigilant clinical monitoring and standardized systemic administration of milrinone on the occurrence of delayed cerebral infarction (DCIn). The "before" period included 277 patients, and the "after" one 453. There was a higher prevalence of Modified Fisher score III/IV and more frequent diagnosis of vasospasm in the "after" period. Conversely, the occurrence of DCIn was reduced with the "after" management strategy (adjusted OR 0.48, 95% CI [0.26; 0.84]). Notably, delayed ischemic neurologic deficits were less prevalent at the time of vasospasm diagnosis (24 vs 11%, p = 0.001 ), suggesting that CTP facilitated early detection. In patients diagnosed with vasospasm, intravenous milrinone was more frequently administered (80 vs 54%, p < 0.001 ) and associated with superior hemodynamics. The present study from a large cohort of aSAH patients suggests, for one part, the interest of CTP in early diagnosis of vasospasm and DCI, and for the other the efficacy of CT perfusion-guided systemic administration of milrinone in both preventing and treating DCIn.

Whole-brain CT Perfusion at Admission and During Delayed Time-window Detects the Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

To evaluate the utility of computed tomography perfusion (CTP) both at admission and during delayed cerebral ischemia time-window (DCITW) in the detection of delayed cerebral ischemia (DCI) and the change in CTP parameters from admission to DCITW following aneurysmal subarachnoid hemorrhage.

METHODS

Eighty patients underwent CTP at admission and during DCITW. The mean and extreme values of all CTP parameters at admission and during DCITW were compared between the DCI group and non-DCI group, and comparisons were also made between admission and DCITW within each group. The qualitative color-coded perfusion maps were recorded. Finally, the relationship between CTP parameters and DCI was assessed by receiver operating characteristic (ROC) analyses.

RESULTS

With the exception of cerebral blood volume (P=0.295, admission; P=0.682, DCITW), there were significant differences in the mean quantitative CTP parameters between DCI and non-DCI patients both at admission and during DCITW. In the DCI group, the extreme parameters were significantly different between admission and DCITW. The DCI group also showed a deteriorative trend in the qualitative color-coded perfusion maps. For the detection of DCI, mean transit time to the center of the impulse response function (Tmax) at admission and mean time to start (TTS) during DCITW had the largest area under curve (AUC), 0.698 and 0.789, respectively.

CONCLUSION

Whole-brain CTP can predict the occurrence of DCI at admission and diagnose DCI during DCITW. The extreme quantitative parameters and qualitative color-coded perfusion maps can better reflect the perfusion changes of patients with DCI from admission to DCITW.

Impact of Implementing an Elaborated CT Perfusion Protocol for Aneurysmal SAH on Functional Outcome: CTP Protocol for SAH

BACKGROUND AND PURPOSE

The acute phase of aneurysmal SAH is characterized by a plethora of impending complications with the potential to worsen patients' outcomes. The aim of this study was to evaluate whether an elaborated CTP-based imaging protocol during the acute aneurysmal SAH phase is able to prevent delayed infarctions and contribute to a better outcome.

MATERIALS AND METHODS

In 2012, an elaborated CTP-based protocol was implemented for the management of patients with aneurysmal SAH. Retrospective analysis of patients with aneurysmal SAH treated from 2010 to 2013 was performed, comparing the patients treated before (group one, 2010-2011) with those treated after the protocol implementation (group two, 2012-2013) with regard to delayed infarctions and outcome according to the mRS at 3-months' follow-up.

RESULTS

A total of 133 patients were enrolled, of whom 57 were included in group 1, and 76, in group 2. There were no significant differences between the groups concerning baseline characteristics. In the multivariate analysis, independent predictors of a good outcome (mRS ≤ 2) were younger age (P < .001), lower World Federation of Neurosurgical Societies grade (P < .001), absence of delayed infarction (P = .01), and management according to the CTP protocol (P = .01). Larger or multiple infarctions occurred significantly more often in group 1 compared with group 2 (88% versus 33% of all delayed infarctions, P = .03). The outcome in group 2 was significantly better compared with group 1 (P = .005).

CONCLUSIONS

The findings suggest that implementation of an elaborated CTP protocol is associated with a better outcome. An earlier initiation of further diagnostics and treatment with prevention of large territorial and/or multiple infarctions might have led to this finding.

Association Between Spreading Depolarization and Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: Post Hoc Analysis of a Randomized Trial of the Effect of Cilostazol on Delayed Cerebral Ischemia

BACKGROUND

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) remains an important problem with a complex pathophysiology. We used data from a single-center randomized trial to assess the effect of a phosphodiesterase inhibitor, cilostazol, in patients with aneurysmal SAH to explore the relationships of DCI with vasospasm, spreading depolarization (SD) and microcirculatory disturbance.

METHODS

A post hoc analysis of a single-center, prospective, randomized trial of the effect of cilostazol on DCI and SD after aneurysmal SAH was performed. From all randomized cohorts, patients who underwent both SD monitoring and digital subtraction angiography (DSA) on day 9 ± 2 from onset were included. Cerebral circulation time (CCT), which was divided into proximal CCT and peripheral CCT (as a measure of microcirculatory disturbance), was obtained from DSA. Logistic regression was conducted to determine factors associated with DCI.

RESULTS

Complete data were available for 28 of 50 patients. Of the 28 patients, 8 (28.5%) had DCI during the study period. Multivariate analysis indicated a strong association between the number of SDs on the day DSA was performed (i.e., a delayed time point after SAH onset) and DCI (odds ratio 2.064, 95% confidence interval 1.045-4.075, P = 0.037, area under the curve 0.836), whereas the degree of angiographic vasospasm and peripheral CCT were not significant factors for DCI.

CONCLUSIONS

There is a strong association between SD and DCI. Our results suggest that SD is an important therapeutic target and a potentially useful biomarker for DCI.

[Significance of CT perfusion examination of cerebral blood flow for assessing the risk of brain ischemia in patients with intracranial arterial aneurysm ruptures]

Prognosing the outcome of cerebral ischemia in the acute SAH phase still remains the topical issue for clinical practice because this largely affects the choice of an optimal timing of aneurysm clipping. The traditional criteria are often not effective enough to predict changes in cerebral ischemia, especially in patients in a compensated or subcompensated state who often develop delayed ischemia, which may lead to serious complications. The introduction of a CT perfusion technique for evaluating the volumetric cerebral blood flow stimulated the development of a new stage in investigation of cerebral ischemia in non-traumatic SAH.

PURPOSE

The study purpose was to evaluate the significance of cerebral blood flow indicators obtained by CT perfusion for prediction of delayed cerebral ischemia and postoperative ischemic complications to optimize treatment of patients with ruptures of intracranial arterial aneurysms.

MATERIAL AND METHODS

The study included 70 patients who underwent aneurysm clipping and 42 non-operated patients. The inclusion criteria were as follows: WFNS grade I-III condition, vasospasm according to transcranial Doppler sonography, and availability of CT scans, including CT perfusion data. The vasospasm severity and perfusion indicators _(rCBV and MTT) were evaluated. The severity of subarachnoid and ventricular hemorrhage was evaluated according to the A. Hijdra method. The final results were evaluated using a clinical-statistical method, including ROC analysis.

RESULTS

An analysis of the obtained data revealed that the risk of delayed cerebral ischemia and postoperative ischemia increases significantly if the baseline hemispheric CBF value is below a threshold of 40 ml/100 g/min, and the baseline MMT indicator is above a threshold of 5 s. There was asymmetry of these CT perfusion indicators due to a larger deviation from the threshold values in the homolateral hemisphere compared to the opposite side. The ROC analysis results demonstrated diagnostic sensitivity and diagnostic specificity of the CT perfusion technique.

CONCLUSION

The CT perfusion data together with the SAH severity and localization indicators may be used as predictors for the cerebral ischemia outcome in choosing the optimal timing of aneurysm clipping during the acute SAH period in patients in a WFNS grade I-III condition and with signs of mild or moderate vasospasm.

The association of neutrophil-to-lymphocyte ratio and delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage: possible involvement of cerebral blood perfusion

Background and purpose: Emerging evidence suggests that systemic inflammation is associated with the pathophysiological process of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). This study aimed to investigate the association of white blood cell (WBC) count and neutrophil-to-lymphocyte ratio (NLR) with the occurrence of DCI in SAH patients. Methods: A total of 122 patients diagnosed with aSAH within 72 h of onset were retrospectively enrolled. The count of WBC, neutrophil count (NC), and lymphocyte (LC) was collected on admission. Computed tomography perfusion was performed within 7 days after SAH. The occurrence of DCI was recorded during the hospitalization. Results: Among enrolled patients, 43 (35.2%) developed DCI during hospitalization. Patients who developed DCI had a higher count of WBC, NC, and NLR as well as a lower count of LC. NC and NLR were independently associated with the occurrence of DCI, while NLR was the best predictive parameter according to the receiver operating characteristic curve. Moreover, there was a strong correlation between NLR and mean cerebral blood flow, mean transit time and mean time to peak. Conclusion: Leukocytosis is an early pathology of SAH, and NLR may be a practical predictor for the occurrence of DCI in SAH patients.