Relative safety of intravenous digital subtraction angiography over other methods of carotid angiography and impact on clinical management of cerebrovascular disease

Diagnostic feasibility of middle cerebral artery stenosis or occlusion evaluated by TCCS and CEUS: Repeatability, reproducibility, and diagnostic agreement with DSA

AIM

This study aimed to evaluate the feasibility of transcranial color-coded sonography (TCCS) and contrast-enhanced ultrasound (CEUS) in assessing middle cerebral artery (MCA) stem stenosis or occlusion compared to digital subtraction angiography (DSA).

METHODS

A total of 48 cases including 96 MCAs suspected stem stenosis or obstruction in the MCA were assessed by TCCS, CE-TCCS, and DSA. The diameters of the most severe stenosis (Ds), proximal normal artery (Dn), and diameter stenosis rate of MCA were measured using both the color doppler flow imaging (CDFI) modality of TCCS or CEUS and the CEUS imaging modality. The intraclass correlation coefficients (ICCs) and 95 % confidence intervals (CI) were evaluated, and a weighted Kappa value was used to evaluate the intra-observer agreement, inter-observer agreement, agreement between CDFI modality and DSA stenosis or occlusion, and agreement between CEUS imaging modality and DSA stenosis or occlusion.

RESULTS

The ICC results indicated excellent repeatability and reproducibility (all ICCs > 0.75; weighted Kappa values >0.81). Compared with DSA, the weighted Kappa values and 95 % CIs of stenosis (the first measurement was taken by two observers) of CDFI modality and CEUS imaging modality were 0.175 (0.041, 0.308) and 0.779 (0.570, 0.988) for observers A and 0.181 (0.046, 0.316) and 0.779 (0.570, 0.988) for observers B respectively.

CONCLUSION

This study indicates that inter- and intra-observer agreements were good for the direct method of measuring percentages of MCA stenosis by TCCS and CEUS. CEUS imaging modality is a new and reliable imaging modality approach to evaluate the MCAs stenosis and occlusion.

Combined carotid and transcranial color-coded sonography in acute ischemic stroke

The objective of this study is to clarify whether the combination of carotid duplex sonography (CD) and transcranial color-coded sonography (TCCS) can accurately detect occlusive lesions in extra and intracranial brain arteries in acute stroke patients, using angiography as the standard. Just before angiography, we performed CD and TCCS in 40 consecutive patients within 24 h after stroke onset. We assessed 320 vessels in total, bilateral internal carotid arteries, vertebral arteries, M1 segments of middle cerebral arteries (MCAs), and P2 segments of posterior cerebral arteries (PCAs). Out of all vessels, 250 (78.1%) could be evaluated by neurosonography because 32 MCAs and 38 PCAs were excluded due to inadequate acoustic windows for TCCS. Significant occlusive lesions (>50%) were observed in 21 out of 250 vessels by neurosonography. Angiography confirmed 20 occlusive lesions as revealed by neurosonography. In the remaining 229 neurosonographically normal vessels, angiography showed no significant lesions except M2 occlusions. The accuracy, sensitivity, and specificity of neurosonography for the detection of occlusive vessels were 99.6, 100 and 99.6%, respectively. Occlusive lesions were observed in 20 of all patients by neurosonography. Nineteen of them were confirmed by angiography. The combination of CD and TCCS can make an accurate diagnosis for significant occlusive lesions in brain arteries in acute stroke patients.

Carotid stenosis in the real world--can Doppler ultrasound replace angiography in a district general hospital setting?

Large trials have confirmed the benefit of carotid endarterectomy in the prevention of stroke in patients with transient ischaemic attacks and > or =70% stenosis of the ipsilateral internal carotid artery. Invasive confirmatory angiography carries some risk, but these patients can be identified by Doppler ultrasound. Non-invasive confirmatory testing with spiral computed tomographic angiography or magnetic resonance angiography is not easily available in many hospitals. In this study, criteria have been developed for use in this unit to identify significant carotid artery stenosis and enable selection for surgery after Doppler ultrasound alone, with known degrees of sensitivity, specificity and accuracy. Carotid arteriography is reserved for a minority of cases.

The effect of angiographic technique and image quality on the reproducibility of measurement of carotid stenosis and assessment of plaque surface morphology

We studied the reproducibility of measurement of carotid stenosis and assessment of plaque surface morphology on 1001 angiograms from a consecutive series of patients entered into the European Carotid Surgery Trial. Inter-observer agreement (Kappa statistic, 95% confidence interval (CI)) for categorization of carotid stenosis, as 0-29%, 30-69% or 70-99% was good (0.68, 0.63-0.73) on 789 conventional or digitally subtracted selective angiograms, and good (0.64, 0.54-0.75) on 174 conventionally and digitally subtracted aortic arch injection angiograms, but was poor (0.29, 0.02-0.80) on 29 intravenous digital subtraction angiograms. Inter-observer agreement did not vary with the method of image acquisition of arterial angiograms, but was dependent on the quality of visualization of the stenosis: kappa = 0.73 (0.67-0.79) for good quality angiograms vs. 0.54 (0.44-0.64) for poor quality angiograms. Inter-observer agreement for assessment of plaque surface morphology was moderate (kappa 0.4-0.6) and did not vary with type of angiography or method of image acquisition. However, ulceration was reported most frequently on selective angiograms and on those angiograms on which the quality of visualization of the stenosis was good. We conclude that the reproducibility of measurement of carotid stenosis and the assessment of plaque surface morphology vary depending on the type of angiography and the quality of visualization of the stenosis. This should be taken into account when validating non-invasive methods of imaging the carotid bifurcation.

Intracranial imaging

This article concentrates on the imaging of intracranial structures and outlines some basic imaging strategies for common clinical presentations.

Non-selective digital subtraction angiography in comparison with selective conventional angiography in the diagnosis of carotid artery disease

In the recent past, non-selective arterial digital subtraction angiography (NSDSA) seemed a less invasive alternative to conventional filmscreen angiography (CFA) in the diagnosis of carotid artery disease. NSDSA obviated the need for selective catheterization with its associated risks but yet took advantage of the DSA method. However, this technique has not found general application although there are no reports that formally assess the (dis)advantages of NSDSA. The aim of our study was to compare the reliability of NSDSA with CFA in evaluation of carotid bifurcations in patients with transient ischemic attacks or partial stroke by reviewing prospectively collected data. Over a 2-year period, 40 patients (upper age limit 65 years) underwent both NSDSA and CFA. Bilateral NSDSA was performed in all 40 patients (80 bifurcations). Bilateral CFA was performed in 27 patients whereas unilateral CFA was carried out in 13 patients (67 bifurcations). Inter- and intra-observer variability for the degree of stenosis was determined by calculation of kappa-values for a 4-point and a 2-point scale. The proportion of interpretable studies was significantly lower in NSDSA. The inter- and intra-observer agreement was on average better in CFA examinations, though the difference was only statistically significant for the inter-observer agreement. The results of our study indicate that images obtained with NSDSA give less reliable information about carotid artery disease than images obtained with CFA. This is in accordance with the fact that NSDSA now seems an abandoned technique.

Complications of intraarterial digital subtraction angiography in patients investigated for cerebral vascular disease

395 patients (236 males, mean age 55.6 years: 159 females, mean age 52.2 years) with suspected transient ischaemic attacks or previous strokes underwent intraarterial digital subtraction angiography (IADSA) over a 3-year period ending in March 1991. All procedures were performed via the femoral approach and the majority consisted of arch studies followed by selective catheterization. 253 (64.1%) of the patients had extracranial vascular disease confirmed at angiography. A retrospective analysis of the patients' records was made to extract all possible complications. Complications were defined as any untoward symptoms or signs occurring within 48 h and which could have been related to the angiogram. Neurological complications occurred in 15 (3.89%) patients. 10 (2.5%) patients had transient complications which resolved completely within 24 h. In three (0.8%) patients the neurological deficit was reversible, recovering fully within 6 days. Two (0.52%) patients were left with residual disability from stroke at 10 days. The permanent neurological complication rate is in the lower range of the rates recorded in previous conventional angiographic studies. We conclude that IADSA is a relatively safe and reliable form of investigation in patients with suspected cerebral vascular disease.

Non-invasive assessment of the Circle of Willis using transcranial pulsed Doppler ultrasound with angiographic correlation

The ability of transcranial pulsed Doppler ultrasound (TCD) to provide a dynamic assessment of the functional capability of the Circle of Willis was assessed using conventional cerebral angiography for anatomic correlation. Eleven patients had normal four-vessel cerebral angiography prior to being investigated with ultrasound. Angiography and ultrasound both demonstrated a functional anterior communicating artery in nine of the eleven patients, giving complete agreement between the two techniques. Posterior communicating arteries were visualized angiographically in all eleven patients. Ultrasound identified bilateral functional vessels in nine, the other two patients having non-functional vessels. In these latter two patients, angiography demonstrated three of the four posterior communicating arteries to be hypoplastic and it was uncertain whether these vessels carried significant blood flow. The fourth posterior communicating artery was shown to have an absent proximal segment of the ipsilateral posterior cerebral artery, with a persistent fetal posterior communicating artery. This anatomical variation is a potential limitation of ultrasound for assessing functional posterior communicating arteries. These preliminary results indicate that a combination of the anatomical (angiographic) and dynamic (ultrasonic) data may prove to be complementary for assessing the Circle of Willis.

Extended use of cranial CT in the evaluation of patients with stroke and transient ischaemic attacks

The hypothesis was explored that patterns of ischaemic brain damage shown by CT may be of greater value in estimating the relevance of angiographic stenosis in the carotico-vertebral arteries in some patients than presenting clinical features. Five angiographic and six CT abnormalities were defined and charted independently in a blinded manner in 312 patients whom clinical features and subsequent management were known. Charts were combined for statistical analysis. Statistically significant associations were found between two types of CT lesion and angiographic abnormalities, but these were present in only 18% of cases. The distribution of clinical features did not differ significantly within this subset compared to the whole population, from which it was concluded that the hypothesis was upheld. Furthermore significantly more patients in this subset were subjected to carotid endarterectomy, suggesting that management decisions may have been modulated by CT findings in some patients.