Related Experiment Video
Updated: Aug 14, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Acute ischemic stroke: accuracy of diffusion-weighted MR imaging--effects of b value and cerebrospinal fluid
Philip E Chen1, Jessica E Simon, Michael D Hill
1Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region, Calgary, AB, T2N 2T9, Canada.
Purpose:
To prospectively determine which diffusion-weighted magnetic resonance (MR) imaging technique (ie, conventional diffusion-weighted MR imaging [b = 1000 or 1500 sec/mm2] or fluid-inversion prepared diffusion [FLIPD] MR imaging [b = 1500 sec/mm2]) is most accurate in depicting acute ischemic stroke at 3 T.
Materials And Methods:
The Health Research Ethics Board approved this study; written informed consent was provided by all participants or their surrogate. Diffusion-weighted MR imaging was performed in 75 consecutive patients (43 men, 32 women; mean age, 64.0 years) with acute ischemic stroke. Two experienced neuroradiologists determined the presence of hyperacute stroke lesions at diffusion-weighted MR imaging by locating areas of hyperintensity that corresponded to regions with a decreased diffusion coefficient. These findings were used as the reference standard. Four raters who were blinded to patient history assessed all images and apparent diffusion coefficient maps for the presence of changes that were consistent with acute ischemic stroke. Accuracy, sensitivity, specificity, negative predictive value, positive predictive value, and inter- and intrarater reliability scores were calculated for each technique.
Results:
Specificity, positive predictive value, and accuracy were not significantly different among the techniques. FLIPD MR images obtained with a b value of 1500 sec/mm2 had decreased sensitivity for acute ischemic stroke (mean, 61.8%; 95% confidence interval [CI]: 55.4%, 67.9%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 82.5%; 95% CI: 77.1%, 87.0%) or 1500 sec/mm2 (mean, 84.5%; 95% CI: 79.3%, 88.9%). FLIPD MR images also had decreased negative predictive value (mean, 96.5%; 95% CI: 95.7%, 97.2%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 98.4%; 95% CI: 97.8%, 98.8%) or 1500 sec/mm2 (mean, 98.6%; 95% CI: 98.1%, 99.0%). Intra- and interrater reliability scores were generally excellent for all three techniques.
Conclusion:
FLIPD MR images obtained with a b value of 1500 sec/mm2 are less suitable for the detection of acute ischemic stroke owing to a decreased sensitivity and negative predictive value. The performance of the two conventional diffusion-weighted MR imaging techniques (b = 1000 and 1500 sec/mm2) was equivalent.
Insights
Conventional diffusion-weighted MRI (b=1000 or 1500 sec/mm2) is more sensitive and has a higher negative predictive value for detecting acute ischemic stroke than FLIPD MRI (b=1500 sec/mm2). Conventional techniques offer equivalent performance for stroke detection.
Area of Science:
- Radiology
- Neuroimaging
- Medical Imaging
Background:
- Acute ischemic stroke diagnosis relies on prompt and accurate imaging.
- Diffusion-weighted magnetic resonance (MR) imaging is crucial for detecting early ischemic changes.
- Optimizing MR imaging techniques is essential for improving diagnostic accuracy in hyperacute stroke.
Purpose of the Study:
- To compare the accuracy of conventional diffusion-weighted MR imaging (DW-MRI) with fluid-inversion prepared diffusion (FLIPD) MR imaging in detecting acute ischemic stroke at 3 Tesla.
- To evaluate the sensitivity, specificity, and predictive values of different DW-MRI techniques for hyperacute stroke detection.
Main Methods:
- A prospective study involving 75 patients with suspected acute ischemic stroke at 3T MRI.
- Comparison of conventional DW-MRI (b=1000 and 1500 sec/mm2) and FLIPD MR imaging (b=1500 sec/mm2).
- Assessment by blinded neuroradiologists using lesion hyperintensity and apparent diffusion coefficient maps; reference standard based on consensus.
Main Results:
- Conventional DW-MRI with b=1000 or 1500 sec/mm2 demonstrated significantly higher sensitivity (82.5% and 84.5%) and negative predictive value (98.4% and 98.6%) for acute ischemic stroke detection compared to FLIPD MR imaging (61.8% and 96.5%).
- No significant differences were found in specificity, positive predictive value, or overall accuracy between the techniques.
- Excellent intra- and interrater reliability was observed for all tested MR imaging techniques.
Conclusions:
- FLIPD MR imaging with b=1500 sec/mm2 is less suitable for detecting acute ischemic stroke due to lower sensitivity and negative predictive value.
- Conventional DW-MRI techniques at b=1000 and 1500 sec/mm2 exhibit equivalent performance and are superior for hyperacute stroke detection.
- Conventional DW-MRI remains the preferred technique for acute ischemic stroke evaluation at 3T.
