Endovascular therapy for stroke is progressing fast and now has strong clinical evidence behind it, but more trained radiologists and specialist services are needed to introduce it more widely.

“There’s been a recent revolution in stroke. After decades of research, clinical trials are now skewed positive and have completely validated endovascular therapy,” explained Prof. Max Wintermark, chief of radiology at Stanford University and President of the American Society of Functional Neuroradiology.

Typical example of a stroke MRI study, including diffusion-weighted imaging (DWI), T2-weighted image (T2), perfusion-weighted imaging or PWI (mean transit time, MTT), and MR angiography (MRA). MRA shows a large occlusion in the left vessel, causing an infarct in the left basal ganglia on DWI, with a large mismatch (PWI defect – arrowheads – larger than the DWI abnormality) (provided by Prof. Max Wintermark).

At today’s session, he will be joining other speakers who will be elaborating on the importance of the technique and how to implement it – especially outside the traditional three to four-hour time window.

Clearing an arterial thrombosis in stroke patients is a highly time-sensitive activity, according to Dr. Raman Uberoi, consultant radiologist at Oxford University Hospitals NHS Foundation Trust, U.K. Patients have to get to hospital within a couple of hours to achieve good results with this procedure, but today there’s growing evidence it can improve outcome even up to 24 hours.

“You can not only prevent some patients from dying, but you can leave them with a healthy and active life – especially younger patients,” he told ECR Today.

Clearing an arterial thrombosis in stroke patients is a highly time-sensitive activity, according to Dr. Raman Uberoi, consultant radiologist at Oxford University Hospitals NHS Foundation Trust, U.K.

Stroke thrombectomies are currently performed by neuro-interventional radiologists and some general interventional radiologists with specific stroke thrombectomy training. As with clots elsewhere in the body, a small tube or catheter is passed through an artery in the groin and used to remove clots from the brain. The patient is then prescribed blood thinners to reduce the risk of further clots occurring.

The key challenge for radiology is the widespread implementation of stroke thrombectomy services, especially in rural areas, Uberoi continued. There needs to be a major increase in the number of centres able to undertake this procedure, which may require a wider range of clinicians trained to perform the procedure – most logically interventional radiologists, as they have the most suitable skillsets. Where that is not practical, cardiologists or even neurologists may need to be trained to do the job.

“It is the sort of thing that comes along once in a generation that can really change how we deliver healthcare,” he said. “And it is something countries should invest in heavily, as it can transform care.”

However, Uberoi warned that some neuro-interventional radiologists believe general interventional radiologists should not be involved in delivering a stroke thrombectomy service. Also, some general interventional radiologists feel they cannot support the delivery of these new services because their workload is too high. Ultimately, though, professionals should work collaboratively and put their turf battles aside to do what is best for patients, he said.

Dr. Achala Vagal, Professor of Radiology at the University of Cincinnati Medical Centre, Ohio, U.S., will speak about advantages and challenges of CT-based evaluation of acute stroke.

As Dr. Achala Vagal from the University of Cincinnati Medical Centre, Ohio, U.S., noted, new guidelines on thrombectomy mean that demand for endovascular treatments has doubled or even tripled in some countries. Diagnostic radiologists and interventional radiologists using CT or MRI need to look at increasing numbers of images of the brain and blood vessels to help with patient selection. They also have to ensure the patient has no additional chronic or unexpected findings, such as a hidden cancer.

“The sheer volume of CT and MR imaging is a real-life challenge and can lead to burnout for radiologists,” she said.

Radiologists also need to think about workflow. Even with a 24-hour window for thrombectomy, patients often arrive late at the hospital because the symptoms of a stroke can be very subtle. Radiologists need to work closely with the rest of the stroke team to decide whether the patient goes immediately from the ambulance to the scanner, receiving all necessary medical checks on the way.

After decades of research, clinical trials are now skewed positive and have completely validated endovascular therapy, according to Prof. Max Wintermark, chief of radiology at Stanford University and President of the American Society of Functional Neuroradiology.

In addition, radiologists need to think about patient selection. As Wintermark explains, the role of his talk and that of Vagal is to outline how the different imaging modalities can help a radiologist to assess whether a patient is a good candidate for endovascular therapy. For example, a CT or MRI scan can show whether the clot or clots are reachable with a tube or catheter.

Imaging of the patient’s brain also needs to show there is viable brain tissue worth saving. When a clot obstructs a vessel to the brain, tissue slowly dies, but at a different rate for each patient. If considerable tissue has died by the time the patient arrives for a thrombectomy, removing the clot can cause a haemorrhage. This is why patients suspected of stroke should go to the closest emergency room as soon as they can, said Wintermark. The more time elapses, the less likely the stroke patient is to have the imaging features that would qualify them for a thrombectomy – even if admitted within 24 hours.

Correct use of imaging within the 24-hour time window can help to personalise endovascular therapy to the needs and likely outcomes of the patient, he concluded.

Transatlantic Course of the ESR and the RSNA
Stroke imaging and endovascular treatment: now and the future
TC 1228 Current status of stroke workup and treatment

Stroke imaging and endovascular treatment: now and the future

  • A. Current status of endovascular management of acute ischaemic stroke: evidence and guidelines
    Raman Uberoi; Oxford/UK
  • B. CT-based evaluation of acute stroke: advantages and challenges
    Achala Vagal; Cincinnati, OH/US
  • C. MRI-based evaluation of acute stroke: advantages and challenges
    Max Wintermark; San Francisco, CA/US

FURTHER READING

Compagne KCJ, Boers AMM, Marquering HA et al (2019) Follow-up infarct volume as a mediator of endovascular treatment effect on functional outcome in ischaemic stroke. Eur Radiol. 29(2):736-744: european-radiology.org/5578

Chung MS, Lee JY, Jung SC et al (2019) Reliability of fast magnetic resonance imaging for acute ischemic stroke patients using a 1.5-T scanner. Eur Radiol. 29(5):2641-2650: european-radiology.org/5812

Ognard J, Dissaux B, Haioun K, Nonent M, Gentric JC, Ben Salem D (2019) A ‘one-stop-shop’ 4D CTA protocol using 320-row CT for advanced imaging in acute ischemic stroke: a technical note. Eur Radiol. 29(9):4930-4936: european-radiology.org/6041

Austein F, Wodarg F, Jürgensen N et al (2019) Automated versus manual imaging assessment of early ischemic changes in acute stroke: comparison of two software packages and expert consensus. Eur Radiol. 29(11):6285-6292: european-radiology.org/6252

Guenego A, Mosimann PJ, Pereira VM et al (2019) Proposed achievable levels of dose and impact of dose-reduction systems for thrombectomy in acute ischemic stroke: an international, multicentric, retrospective study in 1096 patients. Eur Radiol. 29(7):3506-3515: european-radiology.org/6062