Role of volumetric software in the extended treatment window of acute ischemic stroke

Feb 23, 2021

In 2018, two randomized controlled trials, DEFUSE 31and DAWN2 showed the benefit of mechanical thrombectomy in patients with large vessel occlusions (LVO) presented within 6-24 hours after stroke onset. The findings of the DAWN and DEFUSE 3 trial had a profound effect on the treatment guidelines of stroke associations worldwide and prompted the extension of the time window for stroke treatment from 6 hours to 24 hours. This expansion of the treatment window to 24 hours has the potential to benefit a significant proportion of patients with stroke who may have been otherwise categorically denied this treatment.

Results from DAWN and DEFUSE 3 trials                                          

The DEFUSE 3 trial investigated whether patients in the 6-16 hours time window after stroke onset, benefit from endovascular thrombectomy compared to standard medical therapy. Outcomes of the DEFUSE 3 trial were assessed using the modified Rankin scale 90 days after the onset of the stroke. Following this scoring system, patients received a score between 0 and 6, indicating respectively no disabilities and death. Whereas 17% of the patients in the control group were rated as being functionally independent (score 0-2), this percentage increased to 45% in the thrombectomy group. Furthermore, the percentage of patients with a severe disability or death in the thrombectomy group dropped from 42% to 22% in comparison to the control group.1

Similarly, the DAWN trial compared the outcome of endovascular thrombectomy with standard medical therapy in stroke patients in the 6 to 24 hours time window. These results also showed a dramatic improvement in the case of thrombectomy treatment. At 90 days, 49% of patients in the endovascular-treated group had a modified Rankin scale score of 0-2. Whereas in the control arm, this was only 13% of patients.2 

Volumetric inclusion criteria

The inclusion criteria of both trials were based on patients presented to the hospital with occlusion of the internal carotid artery (ICA), occlusion of the first segment of the middle cerebral artery (M1), or both. Further imaging-based selection criteria are based on volumetrics extracted from computerized tomography (CT) perfusion scans. In the DEFUSE 3 trial, patients were included when the cerebral blood flow (CBF) abnormality had a volume of less than 70 mL. In addition, the mismatch volume needed to exceed 15 mL volume with a mismatch ratio larger than 1.8. In the DAWN trial, the volume of the CBF abnormality was taken into account in combination with the NIH stroke scale (NIHSS) score using age-dependent cut-offs. 1,2

A new treatment paradigm in acute/ischemic stroke

Based on these clinical trials, treatment guidelines from most stroke associations have changed, including the American Heart Association/American Stroke Association (AHA/ASA)3, the European Stroke Organisation (ESO)4 and the National Institute for Health and Care Excellence (NICE)5 in the UK. The shift from a time-based treatment perspective to a tissue-status-based approach has made the volumetric assessment of the CBF abnormalities, the mismatch ratio, and the mismatch volume of key importance. The adoption of this new treatment paradigm in an acute setting, therefore, depends on the availability of real-time automated software that is accurate, reproducible, regulatory approved, and affordable.  

About icobrain cva 

icobrain cva is a fully-automated CE-marked and FDA-cleared software solution for the quantitative assessment of tissue perfusion on CT. icobrain cva reports the volume of the core and perfusion lesion by quantifying Tmax and CBF abnormalities together with the mismatch volume and ratio. The report includes an AIF/VOF graph with information on the correctness of the selected arterial input function and the quality of the output. icobrain cva is a cloud-based solution, returning a report and perfusion maps straight into your PACS and e-mail inbox. 

References 

1. Albers et al., Thrombectomy for Stroke at 6 to 16 Hours with Selection by Perfusion Imaging, N Engl J Med. 2018 Feb 22;378(8)-708-718 (DEFUSE 3)

2. Nogueira et al., Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct, N Engl J Med. 2018 Jan 4;378(1)-11-21 (DAWN trial)

3. Powers et al., Guidelines for the Early Management of Patients With Acute Ischemic Stroke: 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke, AHA Journals, 2019;e345 doi:10*1161/STR.0000000000000211

4. Turc, et al. European Stroke Organisation (ESO) - European Society for Minimally Invasive Neurological Therapy (ESMINT) Guidelines on Mechanical Thrombectomy in Acute Ischaemic Stroke, European Stroke Journal. 2019;4(1):6-12

5. NICE guideline 2019: stroke and transient ischaemic attack in over 16s: diagnosis and initial management (NG128): https://www.nice.org.uk/guidance/ng128