Latest Technology for Shorter Treatment Initiation Times and Faster Brain Tissue Evaluation in Acute Stroke Patients

Image interpretation support solutions using deep learning to assist physicians during diagnosis and help improve clinical workflow

At the Stroke Center, the Neurosurgery Department and the Rehabilitation Department have joined with the Stroke Department to form a multidisciplinary stroke care team made up of certified nurse specialists, rehabilitation staff, pharmacists, nutritionists, social workers, and other medical professionals to provide expert treatment. In cooperation with the Trauma & Critical Care Center, the Stroke Center has established a system based on advanced diagnosis using CT, MRI, etc. and a variety of medical and surgical treatment options, including intravenous rt-PA therapy and mechanical thrombectomy. Stroke care is available 24 hours a day for patients with acute ischemic stroke, hemorrhagic stroke, transient ischemic attack, and other conditions. For acute stroke patients, a dedicated hotline to emergency rescue services has been established, and the Stroke Center directly receives patient acceptance requests.
Dr. Kawano explains the acute care system at the Stroke Center, "In acute stroke care, it's essential to transport patients to medical institutions where appropriate treatment can be provided, and also to ensure quick diagnosis and prompt treatment after arrival. At our center, as soon as the emergency rescue team hotline rings, we start preparing for treatment, including intravenous rt-PA therapy and thrombectomy. The goal is to make the time to treatment initiation as short as possible."
In 2019, the center handled 733 emergency outpatient visits, 722 hospitalized patients, 25 intravenous rt-PA therapy cases, 50 thrombectomy cases, and many others. The center has also been certified as a Primary Stroke Center (PSC) by the Japanese Stroke Society.

The phrase "time is brain" is often heard in acute stroke treatment, emphasizing the need to start treatment as quickly as possible. At the same time, the results of recent clinical trials have shown that accurately evaluating stroke patients and selecting the optimal treatment leads to improved outcomes, and the importance of diagnostic imaging for quickly providing precise information on the status of brain tissues is increasing. With regard to the diagnostic imaging of patients with acute stroke, Dr. Kawano says, "Of course, time is important, but we need to accurately determine the condition of the brain in a short time and precisely assess the status of brain tissues."
In January 2019, the Stroke Center adopted a clinical approach employing a "CT-first" protocol in which treatment is selected based on the findings of non-contrast CT, CT perfusion imaging (CTP), and CT angiography (CTA) using Aquilion ONE and the Vitrea workstation for patients with suspected cerebral infarction. In the previous protocol, patients were first examined by plain CT with Aquilion ONE in the Trauma & Critical Care Center on the 1st floor of the hospital, they were then transported to the MRI examination room in the basement floor for MRI scanning, and they were finally transported back to the 1st floor for treatment. This protocol was very inefficient because the patients needed to be moved from one floor of the hospital to another. And even more time was needed to check and prepare the patients for MRI scanning, as well as to perform the relatively time-consuming MRI scans themselves. For these reasons, the hospital decided to adopt a CT-first protocol. This allowed the door-to-needle time to be reduced from 60 minutes when MRI was performed to only about 30 to 35 minutes with the use of CT only. Dr. Kawano notes, "This not only eliminates the time needed to move patients from floor to floor, but also allows us to quickly assess the status of brain tissues and identify occluded vessels using CT and Vitrea in combination. So we can immediately identify which patients should be treated with intravenous rt-PA or mechanical thrombectomy."

In addition, the Protected Code Stroke during the COVID-19 Pandemic, which was modified and issued by the Japanese Stroke Society (JSS-PCS) on April 24, 2020, specifies CT as the diagnostic imaging method of choice for acute stroke patients. Performing simple chest CT at the same time as head CT is recommended for patients with either confirmed or suspected COVID-19 infection. Dr. Kawano adds, "By performing head CT immediately followed by chest CT, we can check for the presence of pneumonia, which is strongly suggestive of COVID-19 infection. The use of CT in stroke treatment during the COVID-19 pandemic is not only better for patients, but also helps to protect hospital staff."

Abierto Reading Support Solution is a medical information solution which was released in July 2020 by Canon Medical Systems as a new product line in the Abierto Series. Abierto Reading Support Solution is equipped with the Abierto Automation Platform, which automates the transmission and reception of image data and the execution of various applications installed in the system, as well as the Findings Navigator, which centrally manages and displays the analysis results. The first application package released for the automation platform was the Abierto Reading Support Solution for Stroke (Stroke Package). The Stroke Package includes four analysis applications: Hemorrhage Analysis, Ischemia Analysis, Brain Perfusion, and Vessel Occlusion Analysis.
The Stroke Department is currently engaged in joint research with Canon Medical Systems to evaluate the clinical usefulness of diagnostic support based on deep learning for acute stroke. At this time, Abierto Reading Support Solution has been introduced ahead of its general market release for validation of its value in the care of acute stroke patients. Dr. Kawano says, "In the treatment of patients with acute stroke, which requires quick and accurate diagnosis, we're currently verifying how automated analysis can save time and reduce the burden on our radiologic technologists. We're also evaluating how the analysis results provided by specialized applications for stroke diagnosis can help to improve the overall workflow of diagnosis and treatment."
After CT scanning is completed, the Automation Platform automatically transfers the images to the server, executes processing by the appropriate applications, and then sends the results to the viewer (PACS). Dr. Kawano explains the benefits of the Automation Platform, "I think the workload on the radiologic technologists performing examinations is greatly reduced because everything is automated after CT scanning is completed. Also, because we have a good idea of how long it takes for the analysis images to be displayed, there's less stress while waiting for the results. I expect the Automation Platform to be very helpful for improving workflow up to the start of treatment for acute stroke, when every second counts."

We are proceeding with verification of the analysis results provided by the various applications included in the Stroke Package. The Hemorrhage Analysis application extracts high-intensity areas from non-contrast brain CT images and displays weighted images. The Ischemia Analysis application extracts low-intensity areas and identifies the areas with suspected "early CT signs". Advanced technology designed and developed using deep learning is used for analysis. The Brain Perfusion application performs analysis by deconvolution using a Bayesian estimation algorithm, as in Vitrea, and generates CBF, CBV, MTT, TTP, and Tmax maps. The ischemic core and the areas suspected to be penumbral are displayed with clear color-coding, and the volume and mismatch ratio of each area is calculated automatically. The Vessel Occlusion Analysis application generates 3D-CTA (MPR, VR) images based on contrast CT images and displays discontinuities in the blood vessels. Dr. Kawano observes, "Experts often disagree on the interpretation of early CT signs, so I think the analysis results provided by Abierto Reading Support Solution are really helpful. We can obtain a good overall understanding of the analysis results of CTP and CTA, and that helps us to quickly reach an accurate diagnosis and select the best treatment."
With regard to Abierto Reading Support Solution, Dr. Kawano states, "The biggest advantage is that Abierto Reading Support Solution can be used as a support tool for image interpretation. For example, it can be very helpful in situations where a stroke specialist isn't available at all times, such as at hospitals that do not have a stroke specialist 24/7. It's now possible to decide whether immediate treatment or transport is needed, which is a great benefit to patients. And for specialists, I think Abierto Reading Support Solution is useful because it can serve as another 'eye' for diagnostic support."
The automation of examination workflows made possible by Abierto Reading Support Solution and the introduction of advanced solutions to support diagnosis are expected to lead to a new era in the care of acute stroke patients.

Reprinted from INNERVISION magazine, September 2020.
Interview conducted on July 3, 2020