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Automated Assessment of Cerebral Arterial Perforator Function on 7T MRI
Tine Arts1, Jeroen C W Siero1,2, Geert Jan Biessels3
1Department of Radiology, Centre for Image Sciences, University Medical Center Utrecht, Utrecht, The Netherlands.
Background:
Blood flow velocity and pulsatility of small cerebral perforating arteries can be measured using 7T quantitative 2D phase contrast (PC) MRI. However, ghosting artifacts arising from subject movement and pulsating large arteries cause false positives when applying a previously published perforator detection method.
Purpose:
To develop a robust, automated method to exclude perforators located in ghosting artifacts.
Study Type:
Retrospective.
Subjects:
Fifteen patients with vascular cognitive impairment or carotid occlusive disease and 10 healthy controls.
Field Strength/Sequence:
7T/cardiac-gated 2D PC MRI.
Assessment:
Perforators were automatically excluded from ghosting regions, which were defined as bands in the phase-encoding direction of large arteries. As reference, perforators were manually excluded by two raters (T.A., J.J.M.Z.), based on perforator location with respect to visible ghosting artifacts. The performance of both censoring methods was assessed for the number of (Nincluded ), mean velocity (Vmean ), and pulsatility index (PI) of the included perforators.
Statistical Tests:
For within-method comparisons, inter- and intrarater reliability were assessed for the manual method, and test-retest reliability was assessed for both methods from repeated 2D PC scans (without repositioning). Intraclass correlation coefficients (ICCs) and their 95% confidence intervals (CIs) were determined for Nincluded , Vmean , and PI for all within-method comparisons. The ICC to compare between the two methods was determined with the use of both (test-retest) scans using a multilevel nonlinear mixed model.
Results:
The automated censoring method showed a moderate to good ICC (95% CI) vs. manual censoring for Nincluded (0.73 [0.58-0.87]) and Vmean (0.90 [0.84-0.96]), and a moderate ICC for PI (0.57 [0.37-0.76]). The test-retest reliability of the manual censoring method was considerably lower than the interrater and intrarater reliability, indicating that scanner noise dominates the uncertainty of the analysis.
Data Conclusion:
The proposed automated censoring method can reliably exclude small perforators affected by ghosting artifacts.
Level Of Evidence:
3.
Technical Efficacy Stage:
1.
Insights
This study developed an automated method to remove artifacts in 7T quantitative 2D phase contrast (PC) MRI, improving the detection of small cerebral perforating arteries. The automated approach reliably excludes ghosting artifacts, enhancing diagnostic accuracy.
Area of Science:
- Neuroimaging
- Cerebrovascular Research
- Medical Physics
Background:
- 7T quantitative 2D phase contrast (PC) MRI measures blood flow in small cerebral perforating arteries.
- Ghosting artifacts from subject movement and pulsating arteries cause false positives in perforator detection.
Purpose of the Study:
- To develop a robust, automated method for excluding perforators located within ghosting artifacts.
- Enhance the accuracy of cerebral perforator detection in 7T PC MRI.
Main Methods:
- Developed an automated method to identify and exclude perforators in ghosting regions.
- Defined ghosting regions as bands in the phase-encoding direction of large arteries.
- Compared automated exclusion with manual exclusion by two raters.
Main Results:
- Automated censoring showed moderate to good reliability (ICC 0.73-0.90) compared to manual censoring for included perforators and mean velocity.
- Moderate reliability (ICC 0.57) was observed for pulsatility index.
- Manual method's test-retest reliability was lower than interrater/intrarater reliability, suggesting scanner noise impact.
Conclusions:
- The automated censoring method reliably excludes small perforators affected by ghosting artifacts.
- This method improves the robustness of cerebral perforator analysis in 7T PC MRI.
