Ct perfusion in oncological imaging

Computed tomography (CT) perfusion is a CT examination modality that enables visualization and non-invasive quantitative assessment of tissue perfusion. Application of CT perfusion in oncology enables non-invasive detection and quantification of neo-angiogenesis (i. e., pathological vascularization) in various malignant tumors. Based on the values of CT perfusion parameters, it is possible to distinguish neoplastic from healthy tissue, malignant from benign tumors, highly aggressive from low-aggressive tumors, and good from poor tumor response to oncological therapy. The basic principle of low-dose CT perfusion is to repeatedly scan the selected region where the tumor is located, using reduced tube voltage and current, at short time intervals after intravenous administration of a small bolus of iodine contrast by an automatic injector at a high flow rate. Using different kinetic-mathematical models allows measurement of certain tissue perfusion parameters, including: blood flow (BF), circulating blood volume (BV), mean transit time (MTT), and vascular permeability (PS or K trans). While results from different CT perfusion software are not comparable, the standardized perfusion value (SPV) is a universal semi-quantitative indicator of tissue perfusion that is independent of the CT perfusion algorithm and can be easily calculated without commercial CT perfusion software. While BF, BV, and PS values are significantly higher in the majority of high-grade malignant tumors compared to low-grade or benign tumors or healthy tissue, MTT is often lower in high-grade tumors. A significant decline in CT perfusion parameter values is a marker of a good response of the neoplasm to the oncological therapy.