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A standardized method of generating time-to-peak perfusion maps in dynamic-susceptibility contrast-enhanced MR
C Nasel1, A Azizi, A Veintimilla
1Department of Radiology, University of Vienna, Austria.
Background And Purpose:
Perfusion MR imaging, performed as dynamic-susceptibility contrast-enhanced MR imaging, is sensitive to hemodynamic risks for patients with cerebrovascular disease. We sought to define a quantitative parameter for perfusion MR imaging, which shows brain areas at hemodynamic risk and enables direct comparison of different perfusion MR imaging examinations.
Methods:
A new standardization procedure for the time-to-peak (TTP) parameter, standardized time to peak (stdTTP), was introduced. The stdTTP automatically calculates a time offset correlated to the earliest enhancing voxels in a section and rescales all TTP values accordingly. Because of a close relation between this offset and stdTTP of early enhancing voxels in central vascular territories (CVTs), stdTTP provides an estimate of the bolus run time between CVTs and related border zones (BZs). The stdTTP in CVTs and BZs was measured in 11 patients without hemodynamic impairment by using high temporal resolution dynamic-susceptibility contrast-enhanced perfusion MR imaging.
Results:
An excellent comparability of different dynamic susceptibility contrast-enhanced MR imaging studies was found. The stdTTP in CVTs was 0.4 +/- 0.5 s (minimum, 0 s; maximum, 1.3 s) for the anterior, 0.5 +/- 0.3 s (minimum, 0 s; maximum, 1.0 s) for the middle, and 1.4 +/- 0.5 s (minimum, 0.4 s; maximum, 2.4 s) for the posterior cerebral artery. In the anterior BZ, stdTTP was 2.3 +/- 0.4 s (minimum, 1.6 s; maximum, 3.2 s), and in the posterior BZ, stdTTP was 2.8 +/- 0.4 s (minimum, 2.0 s; maximum, 3.4 s).
Conclusion:
The results suggest a limit for stdTTP of approximately 3.5 s in the anterior and posterior BZs. The stdTTP could serve as a quantitative measure for the hemodynamic risk assessment of patients with cerebrovascular disease. Because stdTTP can be directly derived from the measured curves, the hemodynamic situation of a patient can be judged with a minimum of computational effort.
Insights
A new standardized time to peak (stdTTP) parameter improves hemodynamic risk assessment in cerebrovascular disease patients. This quantitative measure allows direct comparison of perfusion MR imaging studies with minimal computational effort.
Area of Science:
- Radiology
- Neuroimaging
- Medical Imaging
Background:
- Perfusion MR imaging is crucial for assessing hemodynamic risks in cerebrovascular disease.
- Dynamic-susceptibility contrast-enhanced (DSC) MR imaging is sensitive to these risks.
Purpose of the Study:
- To define a quantitative parameter for perfusion MR imaging.
- To identify brain areas at hemodynamic risk.
- To enable direct comparison of different DSC MR imaging examinations.
Main Methods:
- Introduction of a novel standardization procedure for time to peak (TTP), termed standardized time to peak (stdTTP).
- stdTTP automatically calculates and applies a time offset based on earliest enhancing voxels.
- Measurement of stdTTP in central vascular territories (CVTs) and border zones (BZs) in 11 patients without hemodynamic impairment using high-temporal-resolution DSC perfusion MR imaging.
Main Results:
- Excellent comparability was achieved across different DSC MR imaging studies.
- stdTTP values in CVTs ranged from 0.4 ± 0.5 s (anterior) to 1.4 ± 0.5 s (posterior).
- stdTTP values in border zones were 2.3 ± 0.4 s (anterior) and 2.8 ± 0.4 s (posterior).
Conclusions:
- stdTTP shows a potential limit of approximately 3.5 s in anterior and posterior border zones.
- stdTTP can serve as a quantitative measure for hemodynamic risk assessment in cerebrovascular disease.
- Direct derivation of stdTTP from measured curves allows for rapid hemodynamic situation assessment.