NONINVASIVE MEASUREMENT OF ARTERIAL BLOOD-PLASMA CONCENTRATION OF IODINATED CONTRAST AGENTS FROM CT SCANS OF HUMAN BRAIN

Objective: Our goal was to assess the accuracy of estimating the time course of the arterial plasma concentration of meglumine iothalamate f rom cranial CT images of different vascular structures in the brain. M aterials and Methods: Dynamic CT studies of transcapillary transport i n various brain lesions were analyzed. Vascular structures in the brai n were identified and classified in three categories: arteries, veins, and venous sinuses. Systemic venous blood samples were taken prior to the infusion of meglumine iothalamate and 10 min after completion of the infusion and used as a calibration for the volume averaging fracti on of the image of each vascular structure. A time course of plasma me glumine iothalamate concentration for each of the vascular categories in the CT images was obtained and compared with a variety of methods. Results: Significant differences were found for measurement of plasma meglumine iothalamate concentration from different vascular categories . There was also a disparity between the volume averaging fraction tha t we calculated and what would be expected due to the measured systemi c hematocrit for all vascular structures. Conclusion: The use of image s of veins and venous sinuses consistently underestimated the arterial concentration around the peak values. Correcting the imaged venous si nus values with the measured systemic hematocrit was even less reliabl e. The most accurate method of determining arterial plasma concentrati on of meglumine iothalamate from CT images of brain was to correct the identified arterial vessels for volume averaging.