Consensus Report from Oncology Advisory Board Meeting

Strategies for Prevention and Management of CI-AKI and the Role of Contrast in Oncology CT Settings • 15 Combined with automatic kVp selection tools, reference mAs should be set at a lower level when using a contrast injection protocol that provides higher signal. Importance of Iodine Delivery Rate [3] Two injection parameters influence iodine enhancement in CT: y y Total iodine dose (D) which is calculated as volume (ml) x iodine concentration (g iodine/ml), and y y Iodine delivery rate (IDR) (g iodine/s) which is calculated as flow rate ml/s x iodine concentration (g iodine/ml) where, dose D determines maximum enhancement in venous phase examinations. Iodine delivery rate influences maximum enhancement in first pass examinations such as CT angiography (CTA), arterial phase imaging and perfusion CT. Maintaining high iodine concentration and reducing only volume administered for same injection rate is that IDR remains high resulting in greater enhancement and potentially-improved image quality. High iodine concentration and lower volume, more practically, permits the optimization of injection protocols. Safety and Tolerability [4] Safety and tolerability are influenced by iodine dose, injection volume and flow rate. High flow rate in elderly patients or in patients with poor venous condition may be difficult to achieve or potentially harmful. Higher concentration CM at reduced flow rate is potentially advantageous in reducing intolerability while maintaining a sufficiently high IDR. Reduced total volume of administered CM is beneficial in terms of lowered cardiac preload. High flow rate is associated with: y y greater patient discomfort, y y increased heat sensation, y y higher post-examination heart rate, and y y increased number of premature heartbeats. Here, it will be worthwhile to mention that, isosmolar CM is designed and studied to be more tolerable to patients, compared to high and low osmolar CM. Contrast Medium Osmolality Low-osmolar CM (LOCM) have more cytotoxic effects than iso-osmolarity contrast media (IOCM) based on consistent evidence from cultured tubular cells. In addition, in animal models, IOCM is associated with a lower induction of NOX4- dependent reactive oxygen species (ROS) generation. Also, IOCM exerts fewer vasoconstriction effects than LOCM [5]. Contrast MediumViscosity [6] The role of viscosity in contrast-induced acute kidney injury (CI-AKI) risk is still being debated. All CM, which are more viscous than plasma, and agents with increased osmolality that have lower viscosity may still lead to AKI [5]. Solution viscosity increases when iodine concentration is increased. Injection pressure increases with viscosity. Warming the CM reduces viscosity leading to higher injection rates and better patient tolerability. Hydration Protocol The contrast-induced nephropathy (CIN) Consensus Working Panel found that adequate intravenous (IV) volume expansion with isotonic crystalloids (1-1.5 mL/kg/h), 3-12 hours before the procedure and continued for 6-24 hours afterward, decreases the incidence of CI-AKI in patients at risk. For hospitalized patients, volume expansion should begin 6 hours prior to the procedure and be continued for 6-24 hours post procedure. For outpatients, administration of fluids can be initiated 3 hours before and continued for 12 hours after the procedure. Post-procedure volume expansion is more important than pre-procedure hydration [7]. Drug Interactions to be Avoided [8] y y Discontinue nephrotoxic drugs; y y Non-steroid anti-inflammatory drugs (NSAIDs) must be particularly avoided; y y Maintain an interval of 7 days between sessions of chemotherapy-platinum derivatives; y y Metformin to be avoided/stopped as it prevents renal clearance of lactic acid;