Diagnostic Utility of Computed Tomography Perfusion in the Telestroke Setting

A Comparative Study of CT Perfusion Postprocessing Tools in Medium/Distal Vessel Occlusion Stroke

BACKGROUND AND PURPOSE

CTP has been validated for stroke due to large vessel occlusion, but not for medium or distal vessel occlusions (MDVO). The aim of this study was to evaluate discrepancy of 2 widely used postprocessing tools for CTP in patients with medium/distal vessel occlusion (MDVO) stroke.

MATERIALS AND METHODS

This retrospective single-center cohort study comprised CTP data sets of patients with acute isolated MDVO and disabling stroke. CTP postprocessing included Syngo.via and RapidAI. Perfusion lesions were segmented and compared with regard to volume and spatial distribution of the perfusion abnormalities. For each patient, the results of the 2 postprocessing tools were deemed to represent agreement regarding volume and/or distribution according to a predefined classification scheme. Penumbra volumes were compared between postprocessing tools by using the t test for paired samples.

RESULTS

Fifty CTP data sets from 49 patients (mean age 75.3 ± 10.7 years, 33 male patients) were included. In <30% of patients, the predefined criteria for agreement were met which indicate at least 50% congruence regarding lesion size and lesion location as well as a maximum distance between lesion margins <50 mm. Comparison of tissue at risk volumes revealed outliers, volume disagreement, and distribution disagreement in up to 79.6%. The 2 postprocessing tools disagreed on presence and volume of an infarct core in up to 86% of patients. Penumbra volumes differed significantly between postprocessing tools (P < .001; mean difference 50.5 mL/16.9 mL).

CONCLUSIONS

Despite being in daily use, commercially available postprocessing tools for CTP provide discrepant results in patients with MDVO.

Diagnostic accuracy of large and medium vessel occlusions in acute stroke imaging by neurology residents and stroke fellows: A comparison of CT angiography alone and CT angiography with CT perfusion

INTRODUCTION

Neurology senior residents and stroke fellows are first to clinically assess and interpret imaging studies of patients presenting to the emergency department with acute stroke. The aim of this study was to compare the diagnostic accuracy of brain CT angiography (CTA) with and without CT perfusion (CTP) between neurology senior residents and stroke fellows.

METHODS

In this neuroimaging study, nine practitioners (four senior neurology residents (SNRs) and five stroke fellows (SFs)) clinically assessed and interpreted the imaging data of 50 cases (15 normal images, 21 large vessel occlusions (LVOs) and 14 medium vessel occlusions (MeVOs) in two sessions, 1 week apart in comparison to final diagnosis of experienced neuroradiologist and experienced stroke neurologist consensus. Interrater agreement of CTA alone and CTA with CTP was quantified using kappa statistics, sensitivity, specificity and overall accuracy.

RESULTS

Overall, arterial occlusions were correctly identified in 221/315 (70.1%) with CTA alone and in 266/315 (84.4%) with CTA and CTP (p < 0.001). The sensitivity of overall arterial occlusions detection with CTA alone was 94.2% (95% CI: 90.8%-96.6%) while with addition of CTP was 98% (95% CI: 95.6%-99.3%), The specificity of CTA alone was 74.7% (95% CI: 67.2%-81.3%) which increased with CTP to 84.4% (95% CI: 77.7%-89.8%). The likelihood of correct identification with CTA alone was 156/189 (82.54%) for LVOs and 65/126 (51.59%) for MeVOs. This increased to 169/189 (89.42%; p = 0.054) for LVOs and 97/126 (76.98%; p < 0.001) for MeVOs when the CTA images with CTP were viewed. There was good overall interrater agreement between readers when using CTA alone (k 0.71, 95% CI, 0.62-0.80) and almost perfect (k 0.85, 95% CI, 0.76-0.94) when CTP was added to the image for interpretation. CTA and CTP had a significantly lower median interquartile range (IQR) interpretation time than CTA alone (114 [IQR, 103-120] s vs 156 [IQR, 133-160] s, p < 0.001).

DISCUSSION

In cerebral arterial occlusions, the rate of LVO and MeVOs detections increases when adding CTP to CTA. The accuracy and time for diagnosing arterial occlusion can be significantly improved if CTP is added to CTA. As MeVOs are commonly missed by front-line neurology senior residents or stroke fellows, cases with significant deficits and no apparent arterial occlusions need to be reviewed with neuroradiological expertise.

TACTICS VR Stroke Telehealth Virtual Reality Training for Health Care Professionals Involved in Stroke Management at Telestroke Spoke Hospitals: Module Design and Implementation Study

BACKGROUND

Stroke management in rural areas is more variable and there is less access to reperfusion therapies, when compared with metropolitan areas. Delays in treatment contribute to worse patient outcomes. To improve stroke management in rural areas, health districts are implementing telestroke networks. The New South Wales Telestroke Service provides neurologist-led telehealth to 23 rural spoke hospitals aiming to improve treatment delivery and patient outcomes. The training of clinical staff was identified as a critical aspect for the successful implementation of this service. Virtual reality (VR) training has not previously been used in this context.

OBJECTIVE

We sought to develop an evidence-based VR training module specifically tailored for stroke telehealth. During implementation, we aimed to assess the feasibility of workplace deployment and collected feedback from spoke hospital staff involved in stroke management on training acceptability and usability as well as perceived training impact.

METHODS

The TACTICS VR Stroke Telehealth application was developed with subject matter experts. During implementation, both quantitative and qualitative data were documented, including VR use and survey feedback. VR hardware was deployed to 23 rural hospitals, and use data were captured via automated Wi-Fi transfer. At 7 hospitals in a single local health district, staff using TACTICS VR were invited to complete surveys before and after training.

RESULTS

TACTICS VR Stroke Telehealth was deployed to rural New South Wales hospitals starting on April 14, 2021. Through August 20, 2023, a total of 177 VR sessions were completed. Survey respondents (n=20) indicated a high level of acceptability, usability, and perceived training impact (eg, accuracy and knowledge transfer; mean scores 3.8-4.4; 5=strongly agree). Furthermore, respondents agreed that TACTICS VR increased confidence (13/18, 72%), improved understanding (16/18, 89%), and improved awareness (17/18, 94%) regarding stroke telehealth. A comparison of matched pre- and posttraining responses revealed that training improved the understanding of telehealth workflow practices (after training: mean 4.2, SD 0.6; before training: mean 3.2, SD 0.9; P<.001), knowledge on accessing stroke telehealth (mean 4.1, SD 0.6 vs mean 3.1, SD 1.0; P=.001), the awareness of stroke telehealth (mean 4.1, SD 0.6 vs mean 3.4, SD 0.9; P=.03), ability to optimally communicate with colleagues (mean 4.2, SD 0.6 vs mean 3.7, SD 0.9; P=.02), and ability to make improvements (mean 4.0, SD 0.6 vs mean 3.5, SD 0.9; P=.03). Remote training and deployment were feasible, and limited issues were identified, although uptake varied widely (0-66 sessions/site).

CONCLUSIONS

TACTICS VR Stroke Telehealth is a new VR application specifically tailored for stroke telehealth workflow training at spoke hospitals. Training was considered acceptable, usable, and useful and had positive perceived training impacts in a real-world clinical implementation context. Additional work is required to optimize training uptake and integrate training into existing education pathways.

Most endovascular thrombectomy patients have Target Mismatch despite absence of formal CT perfusion selection criteria

Endovascular thrombectomy (EVT) is the standard of care for large vessel occlusion stroke. Use of Computed Tomographic Perfusion (CTP) to select EVT candidates is variable. The frequency of treatment and outcome in patients with unfavourable CTP patterns is unknown. A retrospective analysis of CTP utilisation prior to EVT was conducted. All CTP data were analysed centrally and a Target Mismatch was defined as an infarct core ≤70 ml, penumbral volume ≥15ml, and a total hypoperfused volume:core volume ratio >1.8. The primary outcome was good functional outcome at 90 days, defined as a modified Rankin Scale (mRS) score 0-2. follow-up infarct volume, core expansion and penumbral salvage volumes were secondary outcomes. Of 572 anterior circulation EVT patients, CTP source image data required to generate objective maps were available in 170, and a Target Mismatch was present in 151 (89%). The rate of 90-day good functional outcome was similar between Target Mismatch (53%) and Large Core Non-Mismatch groups (46%, p = 0.629). Median follow-up infarct volume in the Large Core Non-Mismatch group (104ml [IQR 25ml-189ml]) was larger than that in the Target Mismatch patients (16ml [8ml-47ml], p<0.001). Despite a lack of formal CTP selection criteria, the majority of patients treated at our centres had a Target Mismatch. Patients without Target Mismatch had larger follow-up infarct volumes, but the functional recovery rate was similar to that in Target Mismatch patients. Infarct volumes should be included as objective assessment criteria in the evaluation of the efficacy of EVT in non-Target Mismatch patients.