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Updated: Aug 19, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Tracer delay correction of cerebral blood flow with dynamic susceptibility contrast-enhanced MRI
Masanobu Ibaraki1, Eku Shimosegawa, Hideto Toyoshima
1Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan. iba@akita-noken.go.jp
Insights
Tracer delay significantly impacts cerebral blood flow (CBF) calculations in stroke patients using singular value decomposition (SVD) deconvolution. A new delay correction method improves the reliability of perfusion imaging for hyperacute stroke patients.
Area of Science:
- Neuroimaging
- Medical Physics
- Radiology
Background:
- Dynamic susceptibility contrast-enhanced MRI (DSC-MRI) is used to measure cerebral blood flow (CBF) and mean transit time (MTT).
- Deconvolution algorithms, such as singular value decomposition (SVD), are employed to calculate these perfusion parameters.
- Tracer arrival delays, common in cerebrovascular disease, can introduce significant errors in SVD-based deconvolution.
Purpose of the Study:
- To investigate the impact of tracer delay on CBF measurements using SVD deconvolution.
- To develop and validate a novel method for correcting tracer delay in perfusion imaging.
- To assess the necessity of delay correction for reliable perfusion assessment in hyperacute stroke patients.
Main Methods:
- Simulations were performed to evaluate the effect of tracer delay on CBF underestimation with varying mean transit times (MTTs).
- A pixel-by-pixel least-squares fitting approach was developed to determine and correct for tracer delay.
- The corrected CBF was calculated using SVD deconvolution after time-shifting the arterial input function.
- The delay correction method was applied to DSC-MRI data from nine patients with hyperacute stroke.
Main Results:
- Simulation studies demonstrated that tracer delay leads to CBF underestimation, particularly with shorter MTTs.
- The developed delay correction method rendered CBF measurements insensitive to tracer delay across different vascular models, with a slight increase in CBF fluctuation.
- Application to hyperacute stroke patients revealed that delay correction could alter the contrast of CBF and MTT images.
Conclusions:
- Tracer delay significantly affects CBF quantification using SVD deconvolution in cerebrovascular disease.
- The proposed delay correction method enhances the accuracy and reliability of CBF and MTT measurements.
- Tracer delay correction is crucial for obtaining dependable perfusion imaging in hyperacute stroke patients when employing SVD deconvolution.
Abstract:
Cerebral blood flow (CBF) and vascular mean transit time (MTT) can be determined by dynamic susceptibility contrast-enhanced magnetic resonance imaging and deconvolution with an arterial input function. However, deconvolution by a singular value decomposition (SVD) method is sensitive to the tracer delay that often occurs in patients with cerebrovascular disease. We investigated the effect of tracer delay on CBF determined by SVD deconvolution. Simulation study showed that underestimation of CBF due to tracer delay was larger for shorter MTTs. We developed a delay correction method that determines tracer delay by means of least-squares fitting pixel-by-pixel. The corrected CBF was determined by SVD deconvolution after time-shifting of the measured concentration curve. The simulations showed that the corrected CBF was insensitive to tracer delay irrespective of the vascular model, although CBF fluctuation increased slightly. We applied the delay correction to the CBF and MTT images acquired for nine patients with hyperacute stroke and unilateral occlusion of the middle cerebral artery. We found in some patients that the delay correction modulated the contrast of CBF and MTT images. For hyperacute stroke patients, tracer delay correction is essential to obtain reliable perfusion image when SVD deconvolution is used.
