High-concentration contrast media in neurological multidetector-row CT applications: implications for improved patient management in neurology and neurosurgery

Abstract

Dynamic CT scanning after intravenous injection of iodine contrast medium (CM) was proposed in the very early days of CT. The goal was to characterize tissue by extracting information from the temporal course of enhancement. In the early 1980s, modeling algorithms were already described in the literature for the quantitative calculation of cerebral blood flow (CBF). However, cerebral applications suffered from the insufficient temporal resolution available at that time and the central nervous system was already seen primarily as an MRI domain. The renaissance of dynamic CT in neurological applications came in the middle of the 1990s with the introduction of thrombolytic therapy in acute stroke. With CT being the primary imaging modality, getting additional hemodynamic information from the same device without having to move the patient appeared attractive. Multimodal CT protocols allow a comprehensive diagnosis of the emergency stroke patient in less than 15 minutes by combining nonenhanced CT (NECT), perfusion CT (PCT) and CT angiography (CTA). Dynamic PCT can also render important information in patients with intraaxial brain tumors, allowing differentiation not only between lymphoma and glioma but also between low-grade and high-grade glioma by quantifying local cerebral blood volume (CBV) and permeability of the blood-brain barrier (BBB). However, even if a shorter imaging time permits a reduction in volume of CM, adequate total iodine levels must be preserved for dynamic CT applications. Increased concentrations of iodine are therefore helpful to obtain adequate total iodine levels for imaging.