Using CT in the Diagnosis and Management of Patients with Cerebral Vasospasm

Brain damage evaluation via arterial spin labeling perfusion imaging for patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

Subarachnoid hemorrhage (SAH) is a neurological condition with an annual incidence of 6-22 per 100,000. Despite many advances in diagnosis, the rates of mortality and morbidity in patients remain high. The most important reason for this is complications accompanied by perfusion changes. The aim of our study was to show the perfusion changes with arterial spin labelling (ASL) after SAH.

MATERIALS AND METHODS

In this prospective study, 23 patients diagnosed with aneurysmal SAH were evaluated by ASL perfusion imaging between days 1-3 and 8-10. The mean signal intensities (SI) of both hemispheres from the anterior cerebral artery, middle cerebral artery, and basal ganglia were measured manually according to the region of interest. The relationship between the SI values calculated for both cerebral hemispheres, complications, and grading scales of the side with more intense (ipsilateral) and less (contralateral) bleeding were evaluated.

RESULTS

There was a significant difference in the ipsilateral/contralateral SI ratio (SIIps/ConBGin) (p = 0.015) among all ASL values, including the basal ganglia between days 0-3 and 8-10. There was a significant negative correlation between ASL parameters and rating scale scores. Additionally, when the SIIps/ConBGinDay0-3 ratio cut-off value was ≤ 0.72, the sensitivity and specificity were 57.1% and 100.0%, respectively, in predicting non-fatal complications, and the sensitivity and specificity in predicting all complications, including death, were 55.6% and 100.0%, respectively.

CONCLUSION

Global or regional perfusion decrease can be shown using ASL, with or without the development of vasospasm, without the need for exogenous contrast agent use.

Influence of nimodipine combined with ulinastatin on neurological function and inflammatory reaction in patients with cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE

This study aimed to discuss the influence of nimodipine+ulinastatin on the neurological function and inflammatory reaction in patients with cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH).

METHODS

Overall, 90 patients with CVS after SAH who were admitted to our hospital were enrolled in this study and randomly divided into research and control groups (n = 45 for both groups). On the basis of conventional therapy, patients in the control group were injected with ulinastatin and those in the research group were injected with ulinastatin+nimodipine through an intravenous drip for 7 days with the others the same as those of the control group.

RESULTS

Blood flow velocity in all cerebral arteries was lower in the research group than in the control group after treatment (P < 0.05). Calcitonin gene-related peptide and nitric oxide levels were higher in the research group than in the control group after treatment (P < 0.05). Endothelin levels were lower in the research group than in the control group (P < 0.05). The total effective rate was higher in the research group than in the control group (P < 0.05). Glasgow Coma Scale scores were higher in the research group than in the control group (P < 0.05).

CONCLUSION

The drug combination of nimodipine and ulinastatin improved blood flow and neurological function in patients with CVS after SAH and enhanced the therapeutic efficacy; the underlying mechanism may be associated with the regulation of vascular endothelial dilatation function and the inhibition of relevant inflammatory factors' expression.

Robust Low-Dose CT Perfusion Deconvolution via Tensor Total-Variation Regularization

Acute brain diseases such as acute strokes and transit ischemic attacks are the leading causes of mortality and morbidity worldwide, responsible for 9% of total death every year. "Time is brain" is a widely accepted concept in acute cerebrovascular disease treatment. Efficient and accurate computational framework for hemodynamic parameters estimation can save critical time for thrombolytic therapy. Meanwhile the high level of accumulated radiation dosage due to continuous image acquisition in CT perfusion (CTP) raised concerns on patient safety and public health. However, low-radiation leads to increased noise and artifacts which require more sophisticated and time-consuming algorithms for robust estimation. In this paper, we focus on developing a robust and efficient framework to accurately estimate the perfusion parameters at low radiation dosage. Specifically, we present a tensor total-variation (TTV) technique which fuses the spatial correlation of the vascular structure and the temporal continuation of the blood signal flow. An efficient algorithm is proposed to find the solution with fast convergence and reduced computational complexity. Extensive evaluations are carried out in terms of sensitivity to noise levels, estimation accuracy, contrast preservation, and performed on digital perfusion phantom estimation, as well as in vivo clinical subjects. Our framework reduces the necessary radiation dose to only 8% of the original level and outperforms the state-of-art algorithms with peak signal-to-noise ratio improved by 32%. It reduces the oscillation in the residue functions, corrects over-estimation of cerebral blood flow (CBF) and under-estimation of mean transit time (MTT), and maintains the distinction between the deficit and normal regions.

Advances in transcranial Doppler US: imaging ahead

Transcranial Doppler ultrasonography (US) is a noninvasive, portable technique for evaluating the intracranial vasculature. It has found its most useful clinical application in the detection of vasospasm involving the cerebral vessels after subarachnoid hemorrhage due to aneurysm rupture. The technique has become an integral part of monitoring and managing patients with subarachnoid hemorrhage in the neurologic intensive care unit. In addition, it has proved useful for evaluating the intracranial vasculature in patients with sickle cell disease, stroke, or brain death. Transcranial US originated as a "blind" nonimaging study in which pulsed Doppler technology was used. Identification of the major intracranial vessels and evaluation of those vessels for vasospasm relied on spectral waveforms obtained in each vessel and was based on the depth of the vessel from the skull, the direction of blood flow, and the orientation of the transducer. Recent advances in US technology allow the use of gray-scale, spectral Doppler, and color Doppler flow imaging to directly visualize intracranial vessels, thereby simplifying flow velocity measurements and enhancing their accuracy for vasospasm detection. In particular, measurements of peak systolic velocity and mean flow velocity and calculation of the Lindegaard ratio facilitate the identification of vessels that may be in vasospasm and help differentiate vasospasm from physiologic conditions such as hyperemia and autoregulation. Thus, gray-scale and color Doppler flow imaging offer many advantages over the original pulsed Doppler technique for evaluating the intracranial vasculature.

Role of CT perfusion imaging in the diagnosis and treatment of vasospasm

The current role of CT perfusion (CTP) imaging in the diagnosis and treatment of vasospasm in the setting of aneurysmal subarachnoid hemorrhage is discussed in this article, with specific attention directed towards defining the terminology of vasospasm and delayed cerebral ischemia. A commonly used CTP technique in clinical practice is described. A review of the literature regarding the usefulness of CTP for the diagnosis of vasospasm and its role in guiding treatment are discussed. Recent research advances in the utilization of CTP and associated ongoing challenges are also presented.

Diagnostic accuracy of CT angiography and CT perfusion for cerebral vasospasm: a meta-analysis

BACKGROUND AND PURPOSE

In recent years, the role of CTA and CTP for vasospasm diagnosis in the setting of ASAH has been the subject of many research studies. The purpose of this study was to perform a meta-analysis of the diagnostic performance of CTA and CTP for vasospasm in patients with ASAH by using DSA as the criterion standard.

MATERIALS AND METHODS

The search strategy for research studies was based on the Cochrane Handbook for Systematic Reviews, including literature data bases (PubMed, Embase, Cochrane Database of Systematic Reviews, and the Web of Science) and reference lists of manuscripts published from January 1996 to February 2009. The inclusion criteria were the following: 1) published manuscripts, 2) original research studies with prospective or retrospective data, 3) patients with ASAH, 4) CTA or CTP as the index test, and 5) DSA as the reference standard. Three reviewers independently assessed the quality of these research studies by using the QUADAS tool. Pooled estimates of sensitivity, specificity, LR+, LR-, DOR, and the SROC curve were determined.

RESULTS

CTA and CTP searches yielded 505 and 214 manuscripts, respectively. Ten research studies met inclusion criteria for each CTA and CTP search. Six CTA and 3 CTP studies had sufficient data for statistical analysis. CTA pooled estimates had 79.6% sensitivity (95%CI, 74.9%-83.8%), 93.1%specificity (95%CI, 91.7%-94.3%), 18.1 LR+ (95%CI, 7.3-45.0), and 0.2 LR- (95%CI, 0.1-0.4); and CTP pooled estimates had 74.1% sensitivity (95%CI, 58.7%- 86.2%), 93.0% specificity (95% CI, 79.6%-98.7%), 9.3 LR+ (95%CI, 3.4-25.9), and 0.2 LR- (95%CI, 0.04-1.2). Overall DORs were 124.5 (95%CI, 28.4-546.4) for CTA and 43.0 (95%CI, 6.5-287.1) for CTP. Area under the SROC curve was 98 ± 2.0%for CTA and 97 ± 3.0% for CTP.

CONCLUSIONS

The high diagnostic accuracy determined for both CTA and CTP in this meta-analysis suggests that they are potentially valuable techniques for vasospasm diagnosis in ASAH. Awareness of these results may impact patient care by providing supportive evidence for more effective use of CTA and CTP imaging in ASAH.

The role of transcranial Doppler ultrasonography in the diagnosis and management of vasospasm after aneurysmal subarachnoid hemorrhage

Transcranial Doppler ultrasonography (TCD) is a tool employed by the neurosurgeon and neurointensivist in the management of vasospasm in the intensive care unit after aneurysmal subarachnoid hemorrhage. A review of the current indications, monitoring parameters, indices, and relevance of modern TCD technology is provided, as well as algorithms for the use of TCD ultrasonography in the management of patients with subarachnoid hemorrhage. Other current uses of TCD ultrasonography are also discussed in the setting of neurocritical care.

Noninvasive imaging techniques in the diagnosis and management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating condition, requiring prompt diagnosis and therapeutic intervention as well as close monitoring for the development of complications including vasospasm (VS). Although digital subtraction angiography is still considered the gold standard for the diagnosis of aSAH (and vasospasm), new and less invasive modalities are emerging including ultrasound, CT, CT angiography and CT perfusion, and MR imaging. The current evidence for the use of these newer modalities is described for the diagnosis of aSAH and the management of its sequelae including VS.

Acute cerebral ischemia following intraventricular hemorrhage in moyamoya disease: early perfusion computed tomography findings

The authors present a rare case of an infarction complication 15 days following acute intraventricular bleeding due to moyamoya disease. Before the infarction occurred, perfusion CT imaging disclosed early but reversible ischemic injury on the day of hemorrhage. Dehydration and hypotension are both possibly contributing factors of progressive injury from reversible ischemia due to infarction. Although the patient underwent successful bypass surgery, 1 month after the ictus the neurobehavior evaluation still showed marked executive dysfunction. The authors address that, in hemorrhagic-type moyamoya disease, early perfusion CT scanning is not only a powerful tool to identify the high-risk group of patients who could experience subacute infarction, but also alarms neurosurgeons to eliminate any predisposing factors when it shows reversible ischemic injuries.

Medical management of cerebral vasospasm: present and future

Cerebral vasospasm is one of the major complications of subarachnoid hemorrhage. The delayed occurrence of this complication allows for preventive management and early therapeutic interventions. Yet, accurate and timely diagnosis remains challenging and therapeutic options are rather limited. This review discusses new developments in the diagnosis and medical management of cerebral vasospasm made possible by technological advances and growing understanding of the complex pathophysiology of this disorder. CT protocols including CT perfusion and MRI with diffusion and perfusion sequences are increasingly employed in the evaluation of patients with suspected vasospasm. These radiological studies can add important information to that provided by transcranial Doppler and conventional angiography. Nimodipine for the prevention of delayed functional sequelae and hemodynamic augmentation therapy for the treatment of symptomatic vasospasm remains the mainstay of medical management. Novel strategies under investigation include the use of endothelin receptor antagonists, magnesium sulphate and statins. The value of albumin is being formally studied in an ongoing trial. Interventions to enhance nitric oxide may prove viable in the near future.