Recent advancements are revolutionizing acute ischaemic stroke (AIS) management. In an expert meeting, Professor Keith Muir, SINAPSE Professor of Clinical Imaging & Consultant Neurologist from the University of Glasgow, UK, alongside a panel of local neurologists, discussed innovative approaches to thrombolysis in complex AIS cases. The panel examined how different neuroimaging modalities and artificial intelligence (AI) technologies can aid diagnosis and expand the safe use of thrombolytics. They also explored recent revolutions, successes and challenges of stroke triage networks in Hong Kong and Scotland.
Selecting patients for IVT in challenging cases
Benefits of intravenous thromboÂlytic therapy (IVT) in AIS are highly time-dependent. [J Pers Med 2024;14:955] “Our centre aims to achieve a door-to-needle [DTN] time of <30 minutes and a tissue plasminogen activator [tPA] rate of 20 percent for the National Stroke Centre Accreditation,” shared Dr Kay-Cheong Teo from the Hong Kong Stroke Society. “However, efficiently identifying appropriÂate candidates for thrombolysis remains a key challenge. Common challenging casÂes include minor stroke, stroke mimics, and postsurgical patients.”
“For minor stroke, we need to first assess whether the symptom is truÂly disabling,” explained Teo. “Disability guides our decision, as landmark trials suggest no benefit of IVT for nondisÂabling symptoms. The National InstiÂtutes of Health (NIH) Stroke Scale [NIÂHSS] score alone may underestimate disability, especially for symptoms imÂpacting specific occupations. Therefore, we also consider the patient’s age and occupation, with a practical rule beÂing whether the patient can walk indeÂpendently.” [JAMA 2018;320:156-166; JAMA 2023;329:2135-2144]
“For sudden-onset symptoms that may be stroke mimics, we first exclude reversible causes, such as hypoglycaemia, fever, or inÂtoxication,” Teo added. “Suspicion increases if atrial fibrillation or high cardiovascular risk is present. In such cases, we often proceed with IVT without waiting for CT angiograÂphy [CTA], since IVT is relatively safe even in stroke mimics. For postsurgical patients, the decision is complex. In selected patients and depending on timing and procedure type, thrombolysis may be safely administered after surgery, but careful assessment, disÂcussion with the patient and surgeons, and a thorough risk-benefit analysis are essential due to ongoing bleeding risks.” [NeuroloÂgy 2010;74:1340-1345; Circ Cardiovasc Qual Outcomes 2019;12:e005609; Stroke 2017;48:3034-3039]
Ongoing Asian study: Safety of off-label IVT in AIS patients with recent ingestion of DOACs
“A multicentre, investigator-initiated prospective study in Hong Kong and MainÂland China, now expanding to Malaysia, examines the safety and benefits of IVT with alteplase or tenecteplase in patients with recent use of direct oral anticoaguÂlants [DOACs; last intake occurring within 4–48 hours],” said Dr Bonaventure Yiu-Ming Ip of the Chinese University of Hong Kong (CUHK).
“Early insights from the study suggest IVT can be safely administered even withÂout specific antidotes for factor Xa inhibiÂtors, with trends of improved neurological recovery compared with conservative management,” noted Ip.
“A larger sample size or even ranÂdomized evidence is needed to confirm the safety and efficacy of this approach. Moving forward, the study may upscale recruitment and involve a multiethnic Asian population to bridge critical eviÂdence gaps in Asia,” Ip continued.
Use of low-field MRI
Local neurologists’ initial experience
“Recent collaborative research beÂtween CUHK and Beijing Tiantan HospiÂtal explored using low-field MRI [0.23T] in emergency stroke units [ESUs],” shared Dr Sze-Ho Ma of Hong Kong Stroke SoÂciety. “The compact machine [2.13 x 1.20 x 1.6 m], operable on household power, is suitable for smaller spaces. Innovations in imaging processing, enhanced by AI, enable rapid scans in a total of 4 minutes and 42 seconds for three sequences: DWI, FLAIR, and HEIR, which is designed to detect acute haematoma. An additionÂal MR angiography using time-of-flight takes around 1.5 minutes.” (Figure 1)
“Compared with conventional MRI, this technique reduces scan time and costs while providing comparable image quality and resolution,” noted Ma. LiterÂature reported that low-field MRI (0.23T) achieved >96 percent accuracy and 97 percent sensitivity in detecting ischaemic lesions vs 3.0T MRI, and had a threefold higher likelihood of detection vs nonconÂtrast CT. [Stroke 2024;55:e249-e251; Int J Stroke 2025:17474930251378850]
Benefits of ESU with low-field MRI
An ESU with low-field MRI allows diÂagnosis and treatment within the same room, creating an all-in-one stroke unit from ambulance to needle with no patient transfers. “Given its compact size and no shielding requirements, we converted a storeroom into a fully functional ESU with minimal renovations,” highlighted Ma. “IniÂtial data showed a median DTN time of just 21 minutes and door-to-scan time of 8 minutes, representing a significant imÂprovement. Over the past 6–9 months, approximately 90 patients were screened, with a quarter receiving IVT, despite manÂpower constraints.”
Ma also presented a case illustrating how the DWI-FLAIR mismatch in ESU enÂabled accurate determination of stroke onÂset in a wake-up stroke case, allowing timely thrombolysis and improved NIHSS score.
“Low-field MRI’s impressive resÂolution and rapid imaging support decision-making for thrombolytic treatÂment in AIS, including atypical presentaÂtions or uncertain onset times. Although MR angiography using time of flight (MRA [TOF]) is sensitive, low-field MRI is not yet a full substitute for CTA,” he added.
Downsides of low-field MRI
“While low-field MRI is portable and cost-effective, it has notable limitations. Motion artefacts are common, especially in confused or unstable patients who canÂnot lie still for 5 minutes, making scanning challenging,” noted Ma. “Patients with very low or high blood pressure or poor Glasgow Coma Scale [GCS] score are generally not suitable candidates.”
“Although safe with metal objects, arÂtefacts can occur, and thick slices [about 6 mm] may miss small infarcts. Fine-cut options are available but require extra time,” he added.
“Current evidence suggests that multimodal CT including CT brain, CTA and CT perfusion [CTP] has broader applicability, especially for extended-window thrombolysis and thrombectomy, as CTP can identify viable tissue up to 24 hours after stroke onset,” emphasized Muir.
The panel agreed that imaging should not replace thorough clinical assessment. Rapid onset and focal neurological signs remain the most important factors for acÂcurate diagnosis.
Stroke triage and diversion network models
Stroke Green Channel in Hong Kong
“In Hong Kong, a regional acute public hospital with a comprehensive stroke centre has implemented the Stroke Green Channel. This dedicated pathway from ambulance to treatment has specific time targets for each step to ensure rapid and efficient stroke care,” shared Dr Man-Sum Chi of Hong Kong Stroke Society. (Figure 3)
“Since its launch in January 2025, the median DTN has decreased from 58 to 28.5 minutes, with >80 percent of paÂtients treated within 45 minutes. The meÂdian door-to-puncture time has improved from 103 to 64 minutes, with nearly 88 percent achieving puncture within 90 minutes,” highlighted Chi. “Future plans include deploying patient location tracking system and integrating data with mainÂland China’s stroke registries to further enhance stroke care efficiency.”
Stroke unit workflow in Glasgow
“As one of the largest hospitals in the area and the only provider of 24/7 thromÂbectomy, we often receive potentially treatable patients from hospitals without such services, but transfer times remain a challenge,” Muir noted.
“Our multidisciplinary team works closely from the emergency department to imaging and intervention. Patients are assessed and treated in our dedicated stroke unit, with on-site rehabilitation for continuous care,” Muir added.
“As stroke patients require compreÂhensive vascular imaging, routine imagÂing includes CT and CTA, with CTP perÂformed at the team’s discretion, up to 24 hours after stroke onset. CTP provides focal evidence of ischaemia not visible on other scans, which expedites diagnosis and treatment. We also use a stroke app for data entry and communication, supÂported by software such as RAPID to exÂpedite decisions,” he continued.
“Thrombectomy workflows ensure rapid treatment during work hours, while outside-hours evaluation and imaging are supported by on-call teams and remote tools, with imaging repeated in the mornÂing before intervention,” noted Muir. “Our DTN time is around 45 minutes – shorter than the national average but longer than Hong Kong’s.”
“Both Scotland and Hong Kong face challenges based on local circumstances, but both systems share similar approaches to addressing stroke care issues. The key to better clinical decisions is acquiring higher quality diagnostic information through more routine access to complex imaging, whether low-field MRI or CTP, and ensurÂing rapid and accurate data entry with the help of technology,” Muir concluded.
This special report is supported by an education grant from the industry.
