Biomedical subjects

M J van Osch

Publications and source records attributed to M J van Osch.

4 recordsLinked to original sources

PubMed2001

Correcting partial volume artifacts of the arterial input function in quantitative cerebral perfusion MRI.

To quantify cerebral perfusion with dynamic susceptibility contrast MRI (DSC-MRI), one needs to measure the arterial input function (AIF). Conventionally, one derives the contrast concentration from the DSC sequence by monitoring changes in either the amplitude or the phase signal on the assumption that the signal arises completely from blood. In practice, partial volume artifacts are inevitable because a compromise has to be reached between the temporal and spatial resolution of the DSC acquisition. As the concentration of the contrast agent increases, the vector of the complex blood signal follows a spiral-like trajectory. In the case of a partial-volume voxel, the spiral is located around the static contribution of the surrounding tissue. If the static contribution of the background tissue is disregarded, estimations of the contrast concentration will be incorrect. By optimizing the correspondence between phase information and amplitude information one can estimate the origin of the spiral, and thereupon correct for partial volume artifacts. This correction is shown to be accurate at low spatial resolutions for phantom data and to improve the AIF determination in a clinical example. Magn Reson Med 45:477-485, 2001.

Artifacts↗

PubMed2000

Simultaneous quantitative cerebral perfusion and Gd-DTPA extravasation measurement with dual-echo dynamic susceptibility contrast MRI.

Quantification of cerebral perfusion using dynamic susceptibility contrast MRI generally relies on the assumption of an intact blood-brain barrier. The present study proposes a method to correct the tissue response function that does not require this assumption, thus, allowing perfusion studies in, for example, high-grade brain tumors. The correction for contrast extravasation in the tissue during the bolus passage is based on a two-compartment kinetic model. The method separates the intravascular hemodynamic response and the extravascular component and returns the corrected tissue response function for perfusion quantification as well as the extravasation rate constant of the vasculature. Results of simulation experiments with different degrees of contrast extravasation are presented. The clinical potential is illustrated by determination of the perfusion and extravasation of a glioblastoma multiforme. The correction scheme proves to be fast and reliable even in cases of low signal-to-noise ratio. It is applicable whether extravasation occurs or not. When extravasation is present, application of the proposed method is mandatory for accurate cerebral blood volume measurements. Magn Reson Med 43:820-827, 2000.

Brain Neoplasms↗

PubMed2000

Repeated quantitative perfusion and contrast permeability measurement in the MRI examination of a CNS tumor.

This study reports on the results of quantitative MRI perfusion and contrast permeability measurement on two occasions in one patient. The measurements were separated 81 days in time. The tumor grew considerably in this period, but no change was found with respect to perfusion and contrast permeability. Non-involved white matter values were reproduced to demonstrate repeatability. The presented approach to dynamic susceptibility contrast MRI allows fast and repeatable quantitative assessment of perfusion and is easily integrated in a conventional brain tumor protocol.

Adult↗

PubMed1999

Measurement of cerebral perfusion with dual-echo multi-slice quantitative dynamic susceptibility contrast MRI.

Quantitative cerebral perfusion was measured in vivo using dynamic susceptibility contrast magnetic resonance imaging. A dual-echo acquisition was used to eliminate T(1)-enhancement. The arterial input curve was measured in a separate slice in the neck to minimize partial volume effects. Data analysis was performed using a maximum likelihood expectation maximization method to be less sensitive to noise or contrast arrival time differences. From the contrast response curves obtained, the cerebral blood volume (CBV) and flow (CBF) and the timing parameters mean transit time (MTT), time of appearance (TA), and time-to-bolus peak (TBP) were obtained. Adjacent slices were measured to permit discrimination between intra- and inter-subject variance. The group investigated consisted of 41 subjects without cerebral pathology on anatomical MRI. Perfusion parameters for gray (GM) and white matter (WM) were obtained: CBV (GM) = 6.78 +/- 0.99 ml/100 ml, CBV (WM) = 3.78 +/- 0. 96 ml/100 ml, CBF (GM) = 68.7 +/- 21.2 ml/100 ml/min, CBF (WM) = 35. 8 +/- 12.7 ml/100 ml/min, and average GM/WM ratio for CBV (GM/WM) = 1.87 +/- 0.42 and CBF (GM/WM) = 1.99 +/- 0.48. Measured temporal aspects of perfusion were: mean transit time (MTT) (GM) = 6.4 +/- 1. 8 seconds, MTT (WM) = 6.9 +/- 2.3 seconds, time of appearance (TA) (GM) = 1.4 +/- 0.9 seconds, TA (WM) = 2.0 +/- 1.0 seconds, and time-to-bolus peak (TBP) (GM) = 2.4 +/- 1.4 seconds, TBP (WM) = 3.0 +/- 1.5 seconds. The average values were in agreement with those from the literature. Inter- and intra-person variances were estimated using an ANOVA test, and the sources of variance in the parameters, such as image noise, biological variability, and measurement errors of the arterial input curve were found to be of the same order of magnitude. J. Magn. Reson. Imaging 1999;10:109-117.

Adult↗