In vivo CT measurement of blood-brain transfer constant of iopamidol in human brain tumors |
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Authors: | W.T. Ivan Yeung Ting-Yim Lee Rolando F. Del Maestro Roman Kozak Thomas Brown |
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Affiliation: | (1) Department of Diagnostic Radiology, St. Joseph's Health Centre and University of Western Ontario, N6A 4G5 London, Ontario, Canada;(2) Department of Medical Biophysics, University of Western Ontario, N6A 4G5, Canada;(3) Lawson Family Imaging Research Laboratories, The John P. Robarts Research Institute, N6A 4G5, Canada;(4) Brain Research Laboratory, Clinical Research Unit, Department of Clinical Neurological Sciences, University of Western Ontario, N6A 4G5 London, Ontario, Canada;(5) Lawson Family Imaging Research Laboratories, The John P. Robarts Research Institute, 100 Perth Drive, N6A 5K8 London, Ontario, Canada |
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Abstract: | Summary We have developed an in vivo method of measuring the blood-brain transfer constant (K) of iopamidol and the cerebral plasma volume (Vp) in brain tumors using a clinical X-ray CT scanner. In patient studies, Isovue 300 (iopamidol) was injected at a dosage of 1 ml/kg patient body weight. Serial CT scans of the tumor site and arterial blood samples from a radial artery were taken up to 48 min after injection. The leakage of iopamidol into the brain through the blood-brain barrier was modelled as an exchange process between two compartments, the intravascular plasma space and the tissue interstitial space. Using this model and the concentration measurements in blood plasma and tissue, quantitative estimates of K and Vp in brain tumors were obtained. In addition, distribution of the estimated values of K and Vp in tumors were displayed as false colour functional images overlaid on the conventional CT scan.In a study of twelve patients with anaplastic astrocytoma (n = 3), glioblastoma multiforme (n = 4) or metastases (n = 5) the mean K and VP values in tumor were found to be 0.0273 ± 0.0060 ml/min/g and 0.068 ± 0.11 ml/g respectively. These values were significantly higher than those in grey or white matter in the contralateral normal hemisphere (p < 0.05). The functional images showed variations in K and Vp within the tumor which were difficult to perceive in the original contrast enhanced CT scans. |
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Keywords: | brain tumors blood-brain barrier blood-brain transfer constant x-ray CT iopamidol functional images |
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