Multimodal CT versus MRI in Selecting Acute Stroke Patients for Endovascular Treatment

Multimodal CT imaging characteristics may predict post-reperfusion infarct volume in wake-up stroke patients

Background

Accurate prediction of subsequent infarct volume in acute ischemic stroke (AIS) patients helps determine appropriate interventions and prognosis. The objectives are to assess whether early multimodal CT imaging characteristics of wake-up stroke (WUS) patients could predict post-reperfusion infarct volume and evaluate the accuracy of baseline infarct and penumbra volumes for predicting follow-up infarct volume.

Methods

This retrospective study included WUS patients, last seen well (LSW) >6 h, with multimodal CT imaging at baseline. Baseline non-contrast CT (NCCT) and CT perfusion were analyzed using RAPID software, and CT angiography using maximum intensity projection. Post-reperfusion infarct volume was assessed at 24-h following reperfusion on magnetic resonance diffusion-weighted imaging (DWI). Patients were stratified by treatment module for analyses.

Results

Of 34 eligible patients, 9 (26.5%) received intravenous recombinant tissue plasminogen activator (r-tPA) alone and 25 (73.5%) received both endovascular thrombectomy (EVT) and r-tPA. All patients had a strong correlation between baseline NCCT alberta stroke program early CT score, clot burden score (CBS), Tan score, infarct volume, penumbra volume with 24-h post-reperfusion infarct volume (respectively, r=0.172, P=0.015; r=0.118, P=0.047; r=0.149, P=0.024; r=0.311, P=0.001 and r=0.120; P=0.045). Among reperfusion therapies, WUS patients who received EVT had a significantly lower 24-h post-reperfusion infarct volume and had a significant difference between baseline infarct volume and 24-h post-reperfusion infarct volume (respectively, 82 vs. 14, P=0.032 and 47 vs. 14, P=0.04).

Conclusions

Primarily obtained multimodal CT imaging characteristics may predict post-reperfusion infarct volume in WUS patients, and those who underwent EVT had a significantly lower post-reperfusion infarct volume.

Emerging Techniques and Future Directions: Fast and Portable Magnetic Resonance Imaging

Fast MRI and portable MRI are emerging as promising technologies to improve the speed, efficiency, and availability of MR imaging. Fast MRI methods are increasingly being adopted to create screening protocols for the diagnosis and management of acute pathology in the emergency department. Faster imaging can facilitate timely diagnosis, reduce motion artifacts, and improve departmental MR operations. Point-of-care and portable MRI are emerging technologies that require radiologists to reenvision the role of MRI as a tool with greater accessibility, fewer siting constraints, and the ability to provide valuable diagnostic information at the bedside. Recently introduced commercially available pulse sequences and new MRI scanners are bringing these technologies closer to the patient's clinical setting, and we expect their use to only increase over the coming decade. This article provides an overview of these emerging technologies for emergency radiologists.

Is There a Difference Between LI-RADS 3 to LI-RADS 5 Progression Assessment Using CT Versus MR? A Retrospective, Single-Center, Longitudinal Study of Patients Who Underwent 5082 Radiologic Examinations for Surveillance of Hepatocellular Carcinoma Over a 43-Month Period

OBJECTIVE

The Liver Imaging Reporting and Data System (LI-RADS) has been widely applied to CT and MR liver observations in patients at high-risk for hepatocellular carcinoma (HCC). We investigated the impact of CT vs MR in upgrading LI-RADS 3 to LI-RADS 5 observations using a large cohort of high-risk patients.

METHODS

We performed a retrospective, longitudinal study of CT and MR radiographic reports (June 2013 - February 2017) with an assigned LI-RADS category. A final population of 757 individual scans and 212 high-risk patients had at least one LI-RADS 3 observation. Differences in observation time to progression between modalities were determined using uni- and multivariable analysis.

RESULTS

Of the 212 patients with a LI-RADS 3 observation, 52 (25%) had progression to LI-RADS 5. Tp ranged from 64 - 818 days (median: 196 days). One hundred and three patients (49%) had MR and 109 patients (51%) had CT as their index study. Twenty-four patients with an MR index exam progressed to LI-RADS 5 during the follow-up interval, with progression rates of 22% (CI:13%-30%) at 1 year and 29% (CI:17%-40%) at 2 years. Twenty-eight patients with a CT index exam progressed to LI-RADS 5 during follow-up, with progression rates of 26% (CI:16%-35%) at 1 year and 31% (CI:19%-41%) at 2 years. Progression rates were not significantly different between patients whose LI-RADS 3 observation was initially diagnosed on MR vs CT (HR: 0.81, P = 0.44).

DISCUSSION

MR and CT modalities are comparable for demonstrating progression from LI-RADS 3 to 5 for high risk patients.

Cognitive Function and Prognosis of Multimodal Neuroimage-Guided Thrombectomy on Mild to Moderate Anterior Circulation Infarction Patients with Broadened Therapeutic Window: A Prospective Study

BACKGROUND AND OBJECTIVES

Endovascular mechanical thrombectomy is an important approach for acute ischemic stroke (AIS) treatment. Multimodal neuroimaging methods ideally provide the exact localization, extent, and metabolic activity of target tissues. Post-stroke cognitive impairment has recently been realized to be another major concern except for neurological function impairment. The aim of our study was to carry out a prospective study to compare neurological and cognitive functions after thrombectomy in mild to moderate anterior circulation infarction patients selected by multimodal neuroimaging.

METHODS

Ninety patients were recruited from January 2016 to March 2017 consecutively. Neurological function was assessed by NIHSS before thrombectomy, and 6 h, 24 h, 7 days, 90 days after mechanical thrombectomy. Cognitive functions were evaluated by Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and Hachinski Ischemic Scale.

RESULTS

Patients who received mechanical thrombectomy had significantly better neurological functions at 6 h (p < 0.001), 24 h (p < 0.001), 7 days (p < 0.001), and 90 days (p < 0.001), as well as cognitive functions evaluated by MoCA (26.23 ± 3.85 vs. 24.62 ± 2.25, p = 0.022, n = 85) and MMSE (26.65 ± 2.77 vs. 25.10 ± 2.36, p = 0.023, n = 85) compared to the standard therapy group.

CONCLUSIONS

The current prospective study demonstrated that mechanical thrombectomy can significantly improve neurological and cognitive functions in patients with mild to moderate AIS at broadened therapeutic window under multimodal CT and multimodal MRI imaging.