Radiology Has Multiple Roles in Stroke Management

Studies that show that pretreatment computed tomography (CT) scans can improve a patient's prognosis have been widely accepted. The question remains which modality to use and how.

Most patients are screened with CT, explained Prof. Rüdiger von Kummer, from Dresden University Hospital (Germany), who presented new research at the annual meeting of the European Congress of Radiology (ECR), held in Vienna, Austria in March 2009. CT scanners are more widely available than magnetic resonance imaging (MRI) systems, and CT scans, because of their rapidity, are easier for ill patients to tolerate. CT angiography and perfusion measurement are also more robust techniques than MR angiography (MRA) or MR perfusion imaging.

On the other hand, MRI with diffusion-weighted imaging (DWI) is a highly sensitive technique for detecting small lesions caused by embolic events, which can be missed by CT. MRI is as sensitive as CT in the detection of acute brain hemorrhages, but has a higher sensitivity for old brain hemorrhages.

The application of imaging findings is still under discussion. Based on randomized trials, systemic thrombolysis is approved for the first three hours after stroke only. But these studies have used brain hemorrhage and major infarction alone as contra-indications to drug therapy. A very recent study demonstrated the efficacy of rt-PA (recombinant tissue plasminogen activator), the only approved treatment for acute ischemic stroke up to now, up to 4.5 hours. The identification of patients with small ischemic damage, despite arterial occlusion and extended perfusion impairment, may allow effective reperfusion treatment beyond currently accepted time windows.

Because intravenous thrombolytics may fail to recanalize arterial obstructions, Prof. von Kummer suggested that the angiography suite is prepared for endovascular intervention when drug-based stroke treatments are to be used. Intra-arterial recanalization can then begin immediately if the treatment fails, and may thus considerably improve the patient's prognosis.

Endovascular recanilization can be performed up to six hours after onset of acute stroke, with a good outcome, explained Prof. Gerhard Schroth, director of diagnostic and interventional neuroradiology at Bern University Hospital (Switzerland) at the ECR meeting. Recanalization rates now approach 80%, and one in every three procedures saves a patient from severe impairment.

The procedure consists of injecting a clot-busting drug directly into the thrombus, and no longer just in front of the occlusion site as it used to be performed a few years ago. Recanalization can be achieved for the majority of patients by this way and is associated with improved outcome. Moreover, other mechanical recanalization techniques (retriever devices, percutaneous transluminal angioplasty [PTA], or stenting) can be employed by interventional radiologists if vessel occlusion persists after thrombolysis. Referrals for endovascular treatment can come at any time, and the faster interventional radiologists can respond, the more likely is a successful outcome. "Endovascular treatment is one of the most cost-effective treatments in healthcare, given the high rates of handicap associated with stroke," Prof. Schroth concluded.

Stroke is the third leading cause of death in the West, it is alone responsible for 10% of deaths worldwide and it can leave survivors with significant mental and physical impairment. Prompt management of victims can help reduce fatalities and disabilities, and radiologists can play many roles in diagnosing and treating stroke patients.

The European Congress of Radiology (ECR) is the annual meeting of the European Society of Radiology (ESR), the fastest growing medical society worldwide, currently with 44,500 members.

Related Links:
Dresden University Hospital
Bern University Hospital