Regional Reliability of Combining CT Angiography-source Image and Non-contrast CT in Acute Ischemic Stroke

Abstract

Purpose: CT angiography-source image (CTA-SI) can be used as an effective alternative to diffusion-weighted imaging (DWI) for identifying acute ischemic stroke (AIS). This study investigates the reliability of combining CTA-SI with non-contrast CT (NCCT) for AIS diagnosis, with a focus on how different brain areas affect diagnostic accuracy. Methods: Patients with various subtypes of AIS who underwent NCCT, CTA, and DWI from January to December 2022 were included. Two experienced neuroradiologists analyzed ischemic core across NCCT, CTA-SI, and NCCT+CTA-SI models, evaluating interobserver reliability and lesion detection rate. Results: A total of 304 patients (63% male, age 67.2 ± 11.9 years) with AIS were included. The distribution of stroke subtypes was as follows: 23% large vessel trunk infarction, 46% deep perforator vessel infarction, 9% superficial perforator vessel infarction, 5% watershed infarction, and 17% infratentorial infarction. The interobserver reliability was substantial in the three image models, especially the NCCT+CTA-SI model (all p<0.05). The NCCT+CTA-SI model demonstrated higher lesion detection rate than the NCCT (59.20% vs 48.7%, p<0.05) and CTA-SI model (59.2% vs 45.4%, p<0.05), particularly when detecting large vessel trunk infarction (82.90% vs 58.60%, p<0.05) and deep perforator vessel infarctions (64.80% vs 44.40%, p<0.05). Conclusions: The NCCT+CTA-SI model may be a valuable tool for evaluating AIS when DWI is not feasible. Smaller hospitals might consider adopting this combination for improved stroke diagnosis, highlighting the need for careful evaluation of deep perforator vessel infarction when large vessel trunk infarction is not evident.

Keywords: Acute ischemic stroke; Computed tomography angiography source image; Deep perforator vessel infarction; Large vessel trunk infarction.

Figure 1

Study flowchart.

Figure 2

The schematic diagram of AIS classification. Red: large vessel trunk infarction; yellow: deep perforator vessel infarction; light yellow (lime): superficial perforator vessel infarction; green: watershed infarction; blue: infratentorial infarction.

Figure 3

Typical cases. (A) Large vessel trunk infarction (LTI). An 85-year-old female; onset time 3+ hours. NCCT showed no obvious abnormalities. CT angiography source images (CTA-SI) revealed a large, slightly low attenuation in the left frontal and parietal lobes. The combination of CTA-SI and NCCT depicted left frontal and parietal lobe ischemic stroke. Diffusion-weighted imaging (DWI) showed a large, diffuse, restricted area in the left frontal and parietal lobes. (B) Deep perforator vessel infarction (DPI). A 67-year-old female; onset time 23 hours. NCCT showed no obvious abnormalities. CTA-SI revealed a slightly low attenuation in the right basal ganglia. The combination of CTA-SI and NCCT depicted right basal ganglia ischemic stroke. DWI showed a patchy diffuse restricted area in the right basal ganglia. (C) Superficial perforator vessel infarction (SPI). A 67-year-old female; onset time 24 hours. NCCT showed a slightly low attenuation in the subcortical region of the left parietal lobe. CTA-SI showed no obvious abnormalities. The combination of CTA-SI and NCCT did not indicate the infarct focus. DWI showed a patchy and punctate restricted area in the subcortical region of the left frontal and parietal lobe. (D) Watershed infarction (WI). A 61-year-old male; onset time 3+ hours. NCCT and CTA-SI demonstrated chainlike low attenuation in the left paraventricular region, and there were no signs of old lesions in the surrounding area. DWI showed a chainlike restricted area in the left paraventricular region. (E) Infratentorial infarction (IF). A 78-year-old male; onset time 1+ hours. NCCT and CTA-SI showed no obvious abnormalities in the posterior fossa. Beam hardening artifacts were shown on CTA-SI. DWI showed patchy restricted area in the pons which located in the posterior fossa.