Spiral computed tomography angiography in the assessment of middle cerebral artery occlusive disease

Diagnostic performance of single-phase CT angiography in detecting large vessel occlusion in ischemic stroke: A systematic review

PURPOSE

To systematically review the diagnostic performance of single-phase CT angiography (CTA) in detecting intracranial large vessel occlusion (LVO).

METHOD

MEDLINE and Embase were searched for studies investigating the diagnostic performance of single-phase CTA in detecting LVO. Study quality was assessed. Sensitivity and specificity were calculated and meta-analyzed with a bivariate random-effects model. Heterogeneity was assessed with a chi-squared test.

RESULTS

Eleven studies were included. High risk of bias with regard to "patient selection", "reference standard", and "flow and timing" was present in 4, 1, and 2 studies, respectively. In 7 studies, it was unclear whether reference tests were interpreted blinded to CTA readings. There was variability in types of vessel segments analyzed, resulting in heterogeneous sensitivity and specificity (P < 0.05). Two studies provided data for the proximal anterior circulation (distal intracranial carotid artery, A1-, A2-, M1- and M2-segments), with pooled sensitivity of 88.4 % (95 % CI: 62.2-97.2 %) and pooled specificity of 98.5 % (95 % CI: 33.2-100 %). One study suggested that multiphase CTA improved agreement between nonexperts and an expert in detecting A1-, A2-, M1-, M2-, and M3-segment occlusions compared to single-phase CTA (ĸ = 0.72-0.76 vs. ĸ = 0.32-0.45). No other included study reported added value of advanced CTA (CT perfusion, 4D-CTA, or multiphase CTA) compared to single-phase CTA in detecting proximal anterior circulation LVO.

CONCLUSION

There is lack of high-quality studies on the diagnostic performance of single-phase CTA for LVO detection in the proximal anterior circulation. The added value of advanced CTA techniques in detecting proximal anterior circulation LVO is not completely clear yet.

Comparison of high-resolution MRI with CT angiography and digital subtraction angiography for the evaluation of middle cerebral artery atherosclerotic steno-occlusive disease

Intracranial atherosclerotic disease is increasingly recognized as a major stroke subtype worldwide. Current diagnostic evaluation of atherosclerotic disease of the middle cerebral artery (MCA) relies on detection of stenoses with luminographic imaging studies that do not directly visualize plaque unlike high-resolution MRI. This retrospective study seeks to evaluate the accuracy of high-resolution MRI vessel wall imaging, computed tomographic angiography (CTA) and digital subtraction angiography (DSA) in measuring the degree of stenosis within the MCA. 28 recently symptomatic patients with MCA territory symptoms underwent preliminary imaging with CTA followed by high-resolution MRI at 3-Tesla and definitive imaging with DSA for detection of M1 territory steno-occlusive lesions. Measurements of MCA segments on MRI and CTA were compared with reference to DSA values. Sensitivity and specificity of high-resolution MRI vessel wall imaging, CTA using maximum intensity projection (MIP) and CTA using volume rendering (VR) for the detection of stenosis > 50 % and occlusion were 80.0 and 53.6 %, 72.2 and 72.7 %, and 77.8 and 18.2 %, respectively. MRI-derived values correlated better with DSA (Spearman R = 0.68, p < 0.01) than CTA MIP and VR (Spearman R = 0.45, 0.22; p = 0.02, 0.24, respectively). High-resolution MRI of the MCA is capable of accurately measuring the degree of stenosis and is more sensitive than CTA in a sample of high-risk, symptomatic patients. This study, combined with previous reports, supports the potential of morphological MRI to measure intracranial atherosclerotic plaque non-invasively.

3-Dimensional computed tomographic angiography for use of surgery planning in patients with intracranial aneurysms

BACKGROUND

After subarachnoid haemorrhage (SAH) diagnostic evaluation of the underlying cause is warranted since the rebleeding rate is high. The objective of the study was to answer the question, whether 3-Dimensional computed tomographic angiography (3D-CTA) is able to accurately determine the surgical indications in patients with intracranial aneurysms.

METHODS

After performing 3D-CTA the size of the aneurysm, direction of the aneurysmal dome, neck position and variants of the circle of Willis were analysed. Surgery was performed solely on CTA data in those cases, where the aneurysm was clearly visible. If the findings were negative or inconclusive, intra-arterial digital subtraction angiography (DSA) was also done.

FINDINGS

Between January 2001 and December 2002 100 patients (68 F, 32 M) were examined and 123 aneurysms (86 ruptured and 37 unruptured) were diagnosed. All patients received CTA preoperatively and in 27 patients selective DSA was additionally performed. Postoperatively in 34 patients the operative result was checked by DSA. A good correlation between CTA and the intra-operative findings was present in 92 of 100 patients. One aneurysm was not seen on CTA, but was on DSA. In four cases we could confirm DSA findings in CTA after re-evaluation of the data. In three cases neither CTA nor DSA clearly showed an aneurysm, but it was confirmed during surgery. A good correlation between CTA and DSA was found in 60 of 61 patients (98%). The correlation between CTA and intra-operative findings was good as expected in 92 patients, in 5 patients an aneurysm was detected on re-evaluation. Only one aneurysm could not be demonstrated by CTA but in DSA.

CONCLUSION

CTA is less invasive, less time consuming, cheaper and easier to demonstrate the essential information regarding the aneurysm than DSA. We therefore recommend that following a careful analysis most aneurysms - 92% - can be operated solely on CTA data.

Transcranial doppler sonography and CT angiography in patients with atherothrombotic middle cerebral artery stroke

BACKGROUND AND PURPOSE

Atherothrombotic disease of the middle cerebral artery (MCA) frequently occurs in Asian populations. This abnormality can be noninvasively assessed with transcranial Doppler sonography (TCD) and computed tomographic angiography (CTA). To our knowledge, the usefulness of TCD sonography compared with CTA in the diagnosis of nonembolic MCA disease has not been studied.

METHODS

We prospectively examined 70 patients with clinically suspected atherothrom botic MCA stroke by using TCD sonography and CTA. We excluded patients with a known source of cardiac emboli, significant carotid stenosis, or classic lacunar syndrome. TCD sonography was performed within 2 days of admission, followed by CTA within 7 days after stroke onset.

RESULTS

CTA demonstrated MCA stenosis of more than 50% in 57 patients (81%), whereas only 29 patients (41%) had abnormal TCD findings. CTA showed proximal M1 stenosis, distal M1 stenosis, and M2 disease in 29%, 29%, and 24% of the patients, respectively. Stenotic sites differed between patients with normal TCD results and those with abnormal results. TCD findings correlated well with CTA findings in all patients with proximal M1 stenosis. In contrast, TCD sonography correctly depicted distal M1 or M2 disease in only 24% of the patients.

CONCLUSION

In this population, CTA is superior to TCD sonography in the diagnosis of MCA disease. Abnormal TCD results are highly suggestive of MCA stenosis. However, normal TCD findings do not exclude such lesions, especially in patients with distal M1 or M2 disease. Because distal M1 and M2 disease was found in half of our patients, TCD sonography should not be used as a method to screen for MCA stenosis.

Advances in non-invasive imaging of intracranial vascular disease

Intra-arterial catheter angiography has, in the past, been the mainstay for the investigation of intracranial vascular disease. It is, however, invasive, usually requires in-patients admission, and is associated with a rate of neurological complications between 1% and 3%. In recent years, magnetic resonance angiography (MRA) and CT angiography (CTA) have emerged as non-invasive alternatives for imaging blood vessels and have made a significant impact on neuroradiological investigations. It is the purpose of this article to explain the basic technical principles of these two methods and to give an overview of their current clinical applications.

Vascular risk factors for atherosclerotic lesions of the middle cerebral artery detected by magnetic resonance angiography (MRA)

OBJECTIVES

To examine the relationship between atherosclerotic lesions of the middle cerebral artery (MCA) detected on MRA and vascular risk factors.

MATERIAL AND METHODS

We retrospectively assessed 279 patients (mean age, 69.0+/-11.3 years) who visited the Department of Neurology of Masuda Red Cross Hospital and underwent three-dimensional, time-of-flight MRA of the head between January 1996 and October 1998. Cases of cerebral embolism and internal carotid artery occlusion were excluded. Diagnoses were cerebral infarction (n = 152) and others (n = 127). We evaluated stenotic or occlusive lesions of the MCA (M1 portion), using MRA. Age, sex, history of hypertension, HbA1c, total cholesterol, fasting triglyceride, high density lipoprotein, lipoprotein(a), blood pressure, hematocrit, smoking and left ventricular hypertrophy (LVH) on ECG were included in the analysis.

RESULTS

36 patients (12.9%) had stenotic or occlusive lesions of the MCA on MRA. Univariate analysis showed that age, hypertension and HbA1c were significantly correlated with MCA lesions. Multiple logistic regression analysis showed that HbA C and hypertension were significant and independent predictors for MCA lesions.

CONCLUSION

Hypertension and high serum HbAlc levels may contribute to the development of atherosclerotic lesions of the MCA in Japanese people.

Diagnosis and monitoring of middle cerebral artery occlusion with contrast-enhanced transcranial color-coded real-time sonography in patients with inadequate acoustic bone windows

Transcranial color-coded real-time sonography (TCCS) is an emerging diagnostic technique that allows noninvasive imaging of intracranial vessels within parenchymal structures. However, in some patients, transcranial ultrasound is particularly hindered by insufficient ultrasound penetration through the temporal bone. The present study evaluates whether or not application of an echo-contrast agent in ultrasound-refractory patients with middle cerebral artery (MCA) trunk occlusion enhances image acquisition enough to yield accurate diagnoses. Contrast-enhanced (CE) TCCS examinations, computed tomography scans and angiographic studies were performed in 20 patients with clinical symptoms suggestive of MCA occlusion within 12 h of the onset of symptoms. For comparison, 20 control persons without history or clinical signs for cerebrovascular diseases were examined using CE-TCCS. In none of the patients or control subjects did unenhanced TCCS investigations depict any color-coded vascular signal of an intracranial vessel. After application of 9 mL of 400 mg/mL galactose-based microbubbles, CE-TCCS was performed. In subjects with MCA occlusion, CE-TCCS examinations were repeated within 24 h, 48 h and 5 days after stroke. In stroke patients (n = 20), CE-TCCS showed an occluded MCA main stem in 11 patients, and this vessel was clearly demonstrable on the unaffected side. On the affected side, the posterior cerebral artery (PCA) and anterior cerebral artery (ACA) could be visualized in 8 of 11 subjects; in 3 patients, at least 1 of these vessels was detectable. Angiographic studies confirmed the diagnosis of MCA trunk occlusion in all 11 individuals. In follow-up investigations, 3 stroke patients had angiographic and CE-TCCS examinations consistent with vessel reperfusion. Nine stroke patients had a patent MCA shown in angiographic and CE-TCCS examinations. In the control group, the MCA trunk could be visualized in all subjects by CE-TCCS. CE-TCCS is a sensitive and specific ultrasound method for the diagnosis of MCA trunk occlusion that overcomes the anatomical hindrance of inadequate acoustic bone window. This technique may help to identify patients suitable for thrombolytic therapies and monitor their response.

Emergency imaging of the acute stroke patient

Patients presenting with suspected acute stroke require rapid diagnosis and treatment. Neuroimaging is critical in determining acute-stroke type and thus appropriate management. A review of various neuroimaging techniques and their role in the evaluation of both acute ischemic stroke and acute hemorrhagic stroke is provided.

Variability of magnetic resonance angiography and computed tomography angiography in grading middle cerebral artery stenosis

BACKGROUND AND PURPOSE

Magnetic resonance angiography and computed tomography angiography are new, noninvasive methods to provide images of the cerebral vasculature. The reliability of magnetic resonance angiography and computed tomography angiography when used to grade middle cerebral artery stenosis remains to be established. We sought to study the interobserver and intraobserver variabilities of magnetic resonance angiography and computed tomography angiography in grading middle cerebral artery stenosis.

METHODS

A total of 50 middle cerebral arteries in 25 patients were studied with magnetic resonance angiography and computed tomography angiography. All patients had a history of ischemic stroke. The films were read independently by two observers on separate occasions. Films were shown again to the same observer 4 weeks after the first reading. The degree of middle cerebral artery stenosis was categorized into four grades: normal/mild, moderate, severe, and occluded. The interobserver and intraobserver variabilities were calculated by the kappa statistic method.

RESULTS

Interobserver variability for grading middle cerebral artery stenosis was good (kappa = 0.78) for magnetic resonance angiography and moderate (kappa = 0.51) for computed tomography angiography. There was perfect agreement between two observers in 86% of the vessels shown in magnetic resonance angiography and in 76% of the vessels shown in computed tomography angiography. Intraobserver variability for both imaging methods was good, with the kappa value in the range of 0.70 to 0.76.

CONCLUSIONS

Our results suggest that according to our protocol, magnetic resonance angiography is more reliable than computed tomography angiography in grading middle cerebral artery stenosis.