Subarachnoid Contrast Accumulation and Alberta Stroke Program Early Computed Tomography Score Applied to Contrast Accumulation After Thrombectomy as Predictors of Symptomatic Hemorrhage

BACKGROUND

Areas of contrast accumulation (CA) are commonly found on routine computed tomography (CT) performed immediately after thrombectomy. In the present study, we investigated the types of CA associated with the different outcomes, including symptomatic intracranial hemorrhage (sICH).

METHODS

The present study analyzed the data from 145 patients with anterior circulation stroke who had undergone non-contrast-enhanced conventional CT immediately after thrombectomy. The following variables were investigated: collateral status, failure of recanalization, Alberta stroke program early CT score (ASPECTS) applied to CA lesions and diffusion-weighted imaging infarct lesions, and sICH.

RESULTS

Of the 145 patients, 102 (70.3%) had CA lesions. All types of CA (any CA, cortical CA, subarachnoid CA, and CA ASPECTS) were significantly associated with poor outcomes (modified Rankin scale score >2). In particular, subarachnoid CA (odds ratio, 23.994; 95% confidence interval, 4.696-122.589) and CA ASPECTS (odds ratio, 0.550; 95% confidence interval, 0.404-0.750) were independently associated with sICH. Patients with subarachnoid CA had poorer collateral status and a larger final infarct size than those without subarachnoid CA, although the initial National Institutes of Health stroke scale score and recanalization rate were comparable between the 2 groups. A CA ASPECTS of ≤5 predicted sICH with a sensitivity of 66.7% and a specificity of 92.6% (area under the curve, 0.854).

CONCLUSIONS

Our data suggest that a subarachnoid CA location and CA ASPECTS are predictors of sICH. In particular, a subarachnoid location of CA might signify damage of the subarachnoid collateral arteries, leading to a larger infarct.

Middle Cerebral Artery Residual Contrast Stagnation on Noncontrast CT Scan Following Endovascular Treatment in Acute Ischemic Stroke Patients

BACKGROUND AND PURPOSE

We evaluated the relationship between middle cerebral artery (MCA) residual contrast stagnation on immediate postprocedural noncontrast CT scan and intraparenchymal hemorrhage (IPH) after endovascular treatment in acute ischemic stroke patients.

METHODS

The clinical and imaging data from patients with acute unilateral MCA M1 occlusion who underwent endovascular treatment over a 3.5-year period were reviewed. Bilateral M1 segments were selected on the first postangiography CT scan, and average attenuation was determined in Hounsfield units (HU); the difference between average HU values was calculated. Postprocedural CT scans were also evaluated for presence of IPH, defined as hyperdensity persisting on follow-up CT scans obtained >24-hours postprocedure.

RESULTS

Of 80 patients included in our series; 10/80 developed IPH on immediate postprocedural CT scan. Patients with IPH had a higher (ipsilateral-contralateral) M1 residual attenuation difference (P < .001). An average ipsilateral M1 attenuation which was ≥5 HU greater than contralateral artery had a 3.8 times increase in relative risk of IPH (95% confidence interval: 2-7.1).

CONCLUSION

On immediate postprocedural noncontrast CT scan of stroke patients with acute MCA M1 occlusion after endovascular treatment, higher residual contrast stagnation in the affected MCA, compared to contralateral artery, is associated with an increased risk of IPH.

Immediate CT findings following embolization of cerebral aneurysms: suggestion of blood-brain barrier or vascular permeability change

INTRODUCTION

Although endovascular techniques are widely used for the treatment of cerebral aneurysms, the immediate postprocedural brain CT findings have not been reported. Therefore, in the present study we assessed the immediate postprocedural brain CT findings following the uneventful coil embolization of cerebral aneurysms.

METHODS

Included in the study were 59 patients with 61 cerebral aneurysms after uncomplicated coil embolization. Acute subarachnoid hemorrhage was present with 32 of the 61 aneurysms. All patients underwent a brain CT scan just before and within 2 h after the endovascular treatment. If the postprocedural CT scan revealed any new findings, a follow-up CT scan and/or MRI were performed within 24 h. The variables related to the abnormal CT findings were also evaluated.

RESULTS

Among the 61 immediate brain CT scans, 26 (43%) showed abnormal findings, including cortical contrast enhancement (n=21, 34%), subarachnoid contrast enhancement (n=8, 13%), intraventricular contrast enhancement (n=5, 8%), and striatal contrast enhancement (n=2, 3%). Single or mixed CT findings were also seen. None of the 61 aneurysms was associated with new neurological symptoms after endovascular treatment, and all patients made an uneventful recovery. Abnormal findings were more likely to be found with lower body weight and with increased corrected amounts of contrast material and heparin (P<0.05).

CONCLUSION

After uneventful endovascular treatment of cerebral aneurysms, the immediate brain CT findings can reveal various patterns of abnormal contrast enhancement. Recognizing the immediate brain CT findings is important, as they can mimic various diseases.

Factors contributing to blood-brain barrier disruption following intracarotid injection of nonionic iodinated contrast medium for cerebral angiography: experimental study in rabbits

PURPOSE

This study was performed to investigate the role of injection methods and conditions under a fixed dose of radiographic contrast medium (CM) in respect to promoting blood-brain barrier (BBB) disruption.

MATERIALS AND METHODS

A total of 44 white rabbits (average body weight 2.7 +/- 0.4 kg) were used, and their carotid injection was performed with nonionic CM. The variables assessed for the carotid injections included the following: iodine content (300 or 150 mg I/ml), liquid temperature (37 degrees or 24 degrees C), and the injection time duration (1 or 30 s). The rabbits were divided into five groups. To evaluate BBB disruption, pre- and post-contrast-enhanced magnetic resonance (MR) studies were performed.

RESULTS

Abnormal enhancement of the brain parenchyma in MRI was noted in only one group, which consisted of high-iodine concentration CM injected at a low temperature over a short injection interval. Statistically significant increased values for the percentage of relative enhancement (RE%) were demonstrated (P < 0.05) in comparison with the saline-injected control group.

CONCLUSION

This result suggests variables that may need to be carefully considered to prevent BBB injury induced by nonionic CM for cerebral angiography, especially in the setting of a neurointerventional procedure.

Contrast enhancement and contrast extravasation on computed tomography after intra-arterial thrombolysis in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

The goal of this study was to determine the CT findings and clinical consequences of contrast enhancement and contrast extravasation on CT scans obtained after intra-arterial thrombolytic therapy for treatment of acute ischemic stroke.

METHODS

Sixty-two patients were treated with intra-arterial thrombolysis. All patients underwent nonenhanced CT scans immediately and 24 hours after thrombolytic therapy. Contrast enhancement was defined as a hyperdense lesion that disappeared on a 24-hour follow-up CT scan. Contrast extravasation was defined as a hyperdense lesion with maximum Hounsfield unit >90 that persisted on a follow-up CT scan. We evaluated the differences in the clinical and radiological data between 3 groups: contrast enhancement, contrast extravasation, and control groups.

RESULTS

Contrast enhancement was found in 14 of 62 patients (22.6%); contrast extravasation was seen in 7 (11.3%). Compared with the control group, the contrast enhancement group had a lower recanalization grade (64.3% versus 34.1%, P=0.048) and a lower incidence of hemorrhagic transformation (14.3% versus 43.9%, P=0.047). The contrast extravasation group had a higher incidence of both hemorrhage (100% versus 43.9%, P=0.006) and symptomatic hemorrhage (100% versus 14.6%, P<0.001) than the control group. Poor outcomes were more frequent in the contrast extravasation group (100% versus 38.9%, P=0.003) than the control group.

CONCLUSIONS

Contrast enhancement on CT scans obtained after intra-arterial thrombolysis is usually not associated with hemorrhagic complications. However, contrast extravasation is highly associated with parenchymatous hematoma and should be considered a negative prognostic sign.

Unilateral leptomeningeal enhancement after carotid stent insertion detected by magnetic resonance imaging

BACKGROUND AND PURPOSE

Percutaneous transluminal angioplasty combined with vascular stenting is currently being assessed in the treatment of patients with symptomatic, severe carotid stenosis. The immediate cerebral hemodynamic effects resulting from stenting are not fully understood. This article describes a novel finding: abnormal leptomeningeal enhancement after stenting shown by MRI.

METHODS

Fourteen patients with symptomatic severe carotid bifurcation stenosis underwent MRI within 4 hours before and within 3 hours after attempted carotid stenting. Twelve patients were successfully stented. Part of the MR investigation consisted of the acquisition of T1-weighted images before and after administration of the contrast agent Gd-DTPA, both before and after the procedure.

RESULTS

All 12 patients who underwent successful stenting did not have abnormal enhancement of the leptomeninges before stenting but developed unilateral enhancement following intervention but before the second injection of contrast agent. No contrast enhancement was detected in the 2 patients who had the angiographic procedure but were not stented.

CONCLUSIONS

These findings suggest that abnormal changes to the leptomeningeal vasculature occur during carotid stenting which are not associated with sudden development of neurological symptoms. The anatomic distribution of the enhancement suggests that it is a consequence of the sudden change in brain hemodynamics secondary to the improvement in carotid flow after stenting.

Magnetic resonance imaging-monitored acute blood-brain barrier changes in experimental traumatic brain injury

The authors posit that cellular edema is the major contributor to brain swelling in diffuse head injury and that the contribution of vasogenic edema may be overemphasized. The objective of this study was to determine the early time course of blood-brain barrier (BBB) changes in diffuse closed head injury and to what extent barrier permeability is affected by the secondary insults of hypoxia and hypotension. The BBB disruption was quantified and visualized using T1-weighted magnetic resonance (MR) imaging following intravenous administration of the MR contrast agent gadolinium-diethylenetriamine pentaacetic acid. To avoid the effect of blood volume changes, the maximum signal intensity (SI) enhancement was used to calculate the difference in BBB disruption. A new impact-acceleration model was used to induce closed head injury. Forty-five adult Sprague-Dawley rats were separated into four groups: Group I, sham operated (four animals), Group II, hypoxia and hypotension (four animals), Group III, trauma only (23 animals), and Group IV, trauma coupled with hypoxia and hypotension (14 animals). After trauma was induced, a 30-minute insult of hypoxia (PaO2 40 mm Hg) and hypotension (mean arterial blood pressure 30 mm Hg) was imposed, after which the animals were resuscitated. In the trauma-induced animals, the SI increased dramatically immediately after impact. By 15 minutes permeability decreased exponentially and by 30 minutes it was equal to that of control animals. When trauma was coupled with secondary insult, the SI enhancement was lower after the trauma, consistent with reduced blood pressure and blood flow. However, the SI increased dramatically on reperfusion and was equal to that of control by 60 minutes after the combined insult. In conclusion, the authors suggest that closed head injury is associated with a rapid and transient BBB opening that begins at the time of the trauma and lasts no more than 30 minutes. It has also been shown that addition of posttraumatic secondary insult-hypoxia and hypotension-prolongs the time of BBB breakdown after closed head injury. The authors further conclude that MR imaging is an excellent technique to follow (time resolution 1-1.5 minutes) the evolution of trauma-induced BBB damage noninvasively from as early as a few minutes up to hours or even longer after the trauma occurs.

Neurotoxicity of water-soluble contrast media

A review is given of the development of the water-soluble contrast media (CM) with particular attention to the frquency of neurological complications. A remarkable improvement was achieved following the introduction of the nonionic agent metrizamide in 1974, and a further decrease in neurotoxicity was obtained with the newer nonionic monomers, which have multlple hydroxyl groups included at different sites of the molecule. Theoretical considerations and experimental studies suggest that the neurotoxicity of the new nonionic dimeric agents shuold be at least within the low range seen with the monomeric ones, but further experience is needed before definite conclusions can be drawn in this respect. The mechanisms responsible for the neurological complications seen with CM are unknown but certain critical groups on the CM molecules are known. Several animal models have been developd, which may help predict the degree of neurotoxicity.