Acute stroke imaging: CT with CT angiography and CT perfusion before management decisions

Free-Breathing, Non-Gated Heart-To-Brain CTA in Acute Ischemic Stroke: A Feasibility Study on Dual-Source CT

Purpose

To validate the feasibility of free-breathing, non-gated, high-pitch heart-to-brain computed tomography arteriography (CTA) in acute ischemic stroke and the capability of non-gated heart-to-brain CTA in showing cardiac anatomy.

Materials and Methods

The study protocol was approved by the institutional medical ethics review board. Free-breathing, non-gated, high-pitch heart-to-brain CTA was performed on patients with acute ischemic stroke referred for multimodal CT using a third-generation dual-source CT. Patients scheduled for ECG-triggered heart-to-brain CTA served as controls. Quantitative and/or qualitative image quality of the four cardiac chambers, left atrial appendage, interventricular and interatrial septa, carotid arteries, and coronary arteries were evaluated and compared between the two groups.

Results

Free-breathing, non-gated, high-pitch heart-to-brain CTA was performed on 30 patients with acute ischemic stroke, whereas the control group included 31 cases. There is no significant difference in the image quality of CTAs between the two groups at cardiac chambers and carotid arteries. The image quality of coronary arteries also showed no significant difference between the two groups. The mean dose length products of CTA in the two groups were 129.1 ± 30.5 mGy cm and 121.6 ± 30.3 mGy cm, respectively. Cardiac abnormality can be shown in patients with acute ischemic stroke.

Conclusion

It is feasible to use free-breathing, non-gated, high-pitch heart-to-brain CTA with dual-source CT in acute ischemic stroke for cardiac etiology screening.

Ghost infarct core following endovascular reperfusion: A risk for computed tomography perfusion misguided selection in stroke

BACKGROUND

Computed tomography perfusion (CTP) has been increasingly used for patient selection in mechanical thrombectomy for stroke. However, previous studies suggested that CTP might overestimate the infarct size. The term ghost infarct core (GIC) has been used to describe an overestimation of the final infarct volumes by pre-treatment CTP of >10 ml.

AIM

We sought to study the frequency and predictors of GIC.

METHODS

A prospectively collected mechanical thrombectomy database at a comprehensive stroke center between September 2010 and August 2020 was reviewed. Patients were included if they had a successful reperfusion (mTICI2b-3), a pre-procedure CTP, and final infarct volume measured on follow-up magnetic resonance imaging. Uni- and multivariable analyses were performed to identify predictors of GIC.

RESULTS

Among 923 eligible patients (median [IQR] age, 64 [55-75] years; NIHSS, 16 [11-21]; onset to reperfusion time, 436.5 [286-744.5] min), GIC was identified in 77 (8.3%) of the overall patients and in 14% (47/335) of those reperfused within 6 h of symptom onset. The median overestimation volume was 23.2 [16.4-38.3] mL. GIC was associated with higher NIHSS score, larger areas of infarct core and tissue at risk on CTP, unfavorable collateral scores, and shorter times from onset to image acquisition and to reperfusion as compared to non-GIC. Patients with GIC had smaller median final infarct volumes (10.7 vs. 27.1 ml, p < 0.001), higher chances of functional independence (76.2% vs. 55.5%, adjusted odds ratio (aOR) 3.829, 95% CI [1.505-9.737], p = 0.005), lower disability (one-point-mRS improvement, aOR 1.761, 95% CI [1.044-2.981], p = 0.03), and lower mortality (6.3% vs. 15%, aOR 0.119, 95% CI [0.014-0.984], p = 0.048) at 90 days. On multivariable analysis, time from onset to reperfusion ≤6 h (OR 3.184, 95% CI [1.743-5.815], p < 0.001), poor collaterals (OR 2.688, 95% CI [1.466-4.931], p = 0.001), and higher NIHSS score (OR 1.060, 95% CI [1.010-1.113], p = 0.018) were independent predictors of GIC.

CONCLUSION

GIC is a relatively common entity, particularly in patients with poor collateral status, higher baseline NIHSS score, and early presentation, and is associated with more favorable outcomes. Patients should not be excluded from reperfusion therapies on the sole basis of CTP findings, especially in the early window.

Utilization of Cerebral Blood Flow Study With Computed Tomography for Subdural Hematoma Management

Stroke is among the leading causes of death in the United States, and with our aging population, it will remain a pertinent obstacle in the acute setting. While the field of neuroradiology has advanced tremendously over the years, particularly in improving what we can visualize and quantify, the phrase “time is brain” yet dominates acute stroke management. Optimizing diagnostic protocols for suspected stroke requires a careful balance of data acquisition and speed, as well as taking into account available resources. We present a case of a middle-aged patient with notable risk factors for stroke presenting to the emergency department with altered mental status and suspected stroke. Radiography revealed a large subacute subdural hematoma (SDH) with a mild mass effect on the surface of the brain. The evaluation was supplemented by a computed tomography (CT) and perfusion cerebral blood flow (CBF) study indicating cortical ischemia with penumbra from the SDH compression. SDH evacuation was successfully performed, and patient recovery was achieved within the intensive care unit (ICU). Rapid data acquisition via CBF with CT imaging is crucial for guiding treatment decisions for SDHs. While protocols for ischemic stroke are well-established, SDH protocols are not studied. Thus, we discuss the value of a multimodal CT imaging approach, including CBF studies, in SDH evaluation.

CT-based Techniques for Brain Perfusion

Recent rapid advances in endovascular treatment for acute ischemic stroke highlight the crucial role of neuroimaging especially multimodal computed tomography (CT) including CT perfusion in stroke triage and management decisions. With an increasing focus on changes in cerebral physiology along with time-based matrices in clinical decisions for acute ischemic stroke, CT perfusion provides a rapid and practical modality for assessment and identification of salvageable tissue at risk and infarct core and provides a better understanding of the changes in cerebral physiology. Although there are challenges with the lack of standardization and accuracy of quantitative assessment, CT perfusion is evolving as a cornerstone for imaging-based strategies in the rapid management of acute ischemic stroke.

Multimodal CT techniques for cerebrovascular and hemodynamic evaluation of ischemic stroke: occlusion, collaterals, and perfusion

Neuroimaging of cerebrovascular status and hemodynamics has vastly improved our understanding of stroke mechanisms and provided information for therapeutic decision-making. CT techniques are the most commonly used techniques due to wide availability, rapid acquisition and acceptable tolerance. Numerous multimodal CT techniques have been developed in the last few years. We summarize and explain the various multimodal CT acquisition techniques within three categories based on the scanning mode, namely static mode (single-phase CTA), multiple static mode (multi-phase CTA) and continuous mode (CT perfusion and dynamic CTA). Post-processing methods based on different acquisition modes are also introduced in an easy manner by focusing on the information extracted and products generated. We also describe the applications for these techniques along with their advantages and disadvantages.

Contrast-Enhanced Computed Tomography as a Necessary Scan in Acute Stroke: A Case Series

BACKGROUND

We present a number of exemplary cases where the diagnostic value of the contrast-enhanced computed tomography (CT) after CT angiography in our acute stroke imaging protocol was of fundamental clinical significance.

METHODS

We retrospectively reviewed 7 cases presented to the emergency room, between 2012 and 2014, suspected of acute stroke, with findings diagnosed by the contrast-enhanced CT.

RESULTS

Seven exemplary cases: acute midbrain infarct versus posterior-fossa artefact differentiation in contrast-enhanced CT; differentiation between an M1 occlusion and an internal carotid artery dissection in contrast-enhanced CT; diagnosis of veno-occlusive disease rather than arterial occlusion; bleeding arterial aneurysm revealed by contrast-enhanced CT; previously unsuspected sinus vein thrombosis; sinus vein thrombosis suspected in CT angiography, ruled out by contrast-enhanced CT; and space occupying lesion clearly diagnosed by contrast-enhanced CT.

CONCLUSIONS

Adding contrast-enhanced CT as a part of the acute stroke imaging protocol presents additional diagnoses and avoids pitfalls. Therefore, we consider the contrast-enhanced CT to be essential to the acute stroke setting imaging protocol.

Diagnostic yield of delayed phase imaging in CT angiography of the head and neck: a retrospective study

PURPOSE

To evaluate how often delayed images, obtained during neurovascular CTA, provide unique information relative to early phase imaging alone.

MATERIALS AND METHODS

Informed consent was waived by the institutional review body for this study. Neurovascular CTAs from January through June 2009 were searched to identify those with delayed phase imaging. Reports were reviewed to identify cases where delayed images provided potentially unique information. The studies with potentially unique information were re-interpreted to determine if the information was indeed unique.

RESULTS

645 CTAs with delayed phase imaging were identified. There were 324 men and 310 women (median age 67 years; range 20-96 years). 59 studies (59/645: 9.1%) had findings on the delayed images. There were 13 cases with hemorrhage, with 4 showing progression on delayed views. Of the remaining 46 cases, 28 had occlusion of a vessel that did not reconstitute on the delayed images, 6 had occlusion of a vessel that did reconstitute on the delayed images, 7 had a string sign which was unchanged on the delayed views and 5 had no abnormal findings. Thus in 10 cases the findings were unique to the delayed images (10/645: 1.55%). Four showed active bleeding, three showed proximal occlusion with distal internal carotid filling from ophthalmic collaterals, two showed pial vessels filling distal to proximal MCA occlusion, and one showed retrograde vertebral artery filling due to subclavian steal. 95% confidence limits of the expected incidence of unique information from the delayed phase images are 0.6%-2.5%.

CONCLUSION

Obtaining delayed phase imaging for neurovascular CTA should be an active decision and not the default protocol. This avoids imaging with little, if any value. If delayed images had not been obtained in our cohort, no detriment in patient management would have occurred.

Editorial: Workforce needs for endovascular acute ischemic stroke therapy: myth or reality?

The acute ischemic strokes amenable to intraarterial therapy probably number no more than 20,000 per year in the United States. The future demand for intraarterial reperfusion techniques may change, but the fraction of patients who require intraarterial thrombolysis is currently rather low, and the number of neurointerventionists is adequate. Each hospital caring for patients with acute stroke will need to determine its own demand for intraarterial therapy and employ an adequate supply of qualified neurointerventionists available to meet demand. Comprehensive stroke centers are now being designated and hopefully will foster a rational, regionalized approach to the delivery of endovascular therapies for stroke.

Multimodal endovascular management of acute ischemic stroke in patients over 75 years old is safe and effective

Introduction

Greater attention has been directed to endovascular recanalization of acute ischemic stroke in septuagenarians and above.

Technique

A retrospective chart review was conducted to include patients treated for acute ischemic stroke from 2006 to 2012. All patients underwent initial neurological assessment and non-contrast head CT. Patients treated from 2009 to 2012 additionally received emergent CT angiogram and CT perfusion. 51 patients met the clinical and radiographic criteria and underwent multimodal endovascular revascularization for acute ischemic events.

Results

All patients underwent cerebral angiography and met angiographic criteria for endovascular thrombolysis. 34 patients (67%) were older than 80 years of age. 23 patients (45%) received intravenous tissue plasminogen activator prior to admission. Eight (16%) patients underwent stent placement after intra-arterial thrombolysis, 10 (20%) underwent balloon angioplasty and seven (14%) underwent both angioplasty and stent placement. 21 (41%) required only intra-arterial thrombolytics. An improvement in Thrombolysis in Myocardial Infarction score was noted in 34 patients (67%). The average modified Rankin Scale score on discharge was 3.9. Symptomatic intracranial hemorrhage occurred in three patients (6%); none required surgery. One patient (1.9%) had a postoperative retroperitoneal hematoma, which was managed conservatively. Two fatalities resulted from intraoperative vessel rupture (3.9%), with a combined morbidity and mortality of 27.5%.

Conclusions

Multimodal endovascular recanalization of acute ischemic stroke is a relatively safe treatment option in patients older than 75 years of age. Careful patient selection by clinical and radiographic inclusion criteria is necessary for the successful management of stroke in this age group.