Differentiating intraparenchymal hemorrhage from contrast extravasation on post-procedural noncontrast CT scan in acute ischemic stroke patients undergoing endovascular treatment

INTRODUCTION

This study aimed to identify the imaging characteristics that can help differentiate intraparenchymal hemorrhage from benign contrast extravasation on post-procedural noncontrast CT scan in acute ischemic stroke patients after endovascular treatment.

METHODS

We reviewed the clinical and imaging records of all acute ischemic stroke patients who underwent endovascular treatment in two hospitals over a 3.5-year period. The immediate post-procedural CT scan was evaluated for the presence of hyperdense lesion(s). The average attenuation of the lesion(s) was measured. Intraparenchymal hemorrhage was defined as a persistent hyperdensity visualized on follow-up CT scan, 24 h or greater after the procedure.

RESULTS

Of the 135 patients studied, 74 (55%) patients had hyperdense lesion(s) on immediate post-procedural CT scan. Follow-up scans confirmed the diagnosis of intraparenchymal hemorrhage in 20 of these 74 patients. A receiver operating characteristic analysis showed that the average attenuation of the most hyperdense lesion can differentiate intraparenchymal hemorrhage from contrast extravasation with an area under the curve of 0.78 (p = 0.001). An average attenuation of <50 Hounsfield units (HU) in the most visually hyperattenuating hyperdense lesion had 100 % specificity and 56% sensitivity for identification of contrast extravasations. Petechial hyperdensity was seen in 46/54 (85%) patients with contrast extravasation versus 9/20 (45%) patients with intraparenchymal hemorrhage on the immediate post-procedural CT scan (p < 0.001).

CONCLUSION

An average attenuation <50 HU of the most hyperattenuating hyperdense parenchymal lesion on immediate post-procedural CT scan was very specific for differentiating contrast extravasation from intraparenchymal hemorrhage in acute ischemic stroke patients after endovascular treatment.

A grading scale to predict outcomes after intra-arterial thrombolysis for stroke complicated by contrast extravasation

OBJECTIVE

Contrast extravasation after intra-arterial thrombolysis for stroke occurs frequently and is identifiable on a computed tomographic (CT) scan, but it is often unrecognized or misdiagnosed. Few articles describing this phenomenon have been published. The clinical outcomes of patients after contrast extravasation are poorly understood. We designed a grading system to predict outcomes after contrast extravasation and tested the grading scale prospectively.

METHODS

We studied 27 patients who had contrast extravasation exhibited on a CT scan immediately after intra-arterial thrombolysis. The National Institutes of Health Stroke Scale was used to quantify neurological examinations preoperatively, postoperatively, and at follow-up an average of 3 months later. A grading scale from 0 to 10 was developed from a retrospective analysis of the first 18 patients using odds ratios and Fisher's exact test. The grading system was then applied prospectively to the next 9 consecutive patients.

RESULTS

Six components of the grading system were weighted approximately proportional to corresponding odds ratios: 1) incomplete recanalization (3 points), 2) prolonged angiographic blush (2 points), 3) hyperdensity greater than 150 Hounsfield units (2 points), 4) lesion volume greater than 50 cc exhibited on a CT scan (1 point), 5) lesion in eloquent parenchyma (1 point), and 6) hypodensity demonstrated on an immediate postoperative CT scan (1 point). The contrast extravasation grades for each outcome category (excellent, fair, poor, died) increased in stepwise fashion. There was a direct linear correlation between the assigned grade and National Institutes of Health Stroke Scale score improvement at follow-up.

CONCLUSION

This grading system should prove useful as a preliminary guide for predicting outcomes of patients with contrast extravasation after intra-arterial thrombolysis for stroke. Further analysis in a large cohort of prospective patients is necessary to ensure extensibility.

Angiographic Classification of Cerebral Embolism

Since 1994, we have treated 62 cases with hyperacute cerebral embolism with local intraarterial thrombolysis (LIT), but not all cases showed recanalization. We tried to classify these cases by angiographic results. Angiographically they could be classified into four types; tapering type, fading type, stump type, and edge type. The tapering and fading type had a significantly higher tendency to recanalize than the stump and edge type.

We think these classifications indicate the dissolubility of the cerebral emboli; the former two types dissoluble, the latter two types indissoluble. The tapering and fading type are the good indicators for LIT, but the stump and edge type may not be.