Tailoring Contrast Media Protocols to Varying Tube Voltages in Vascular and Parenchymal CT Imaging:The 10-to-10 Rule

The latest technical developments in CT have created the possibility for individualized scan protocols at variable kV settings. Lowering tube voltages closer to the K-edge of iodine increases attenuation. However, the latter is also influenced by patient characteristics such as total body weight. To maintain a robust contrast enhancement throughout the patient population in both vascular and parenchymal CT scans, one must adapt the contrast media administration protocols to both the selected kV setting and patient body habitus. This article proposes a simple rule of thumb for how to adapt the contrast media protocol to any kV setting: the 10-to-10 rule.</p

Performance of Centargo:A Novel Piston-Based Injection System for High Throughput in CE CT

PURPOSE: To compare an investigational device (MEDRAD(®) Centargo CT Injection System, “Centargo”) to the currently available MEDRAD(®) Stellant CT Injection System (“Stellant”), in terms of efficiency, injector performance, and user satisfaction. PATIENTS AND METHODS: A total of 425 patients at two sites were enrolled; 198 patients in phase one, a randomized study (98 Stellant and 100 Centargo). The second observational phase included 227 patients who were injected with Centargo. Phase one recorded times for setup, disassembly, and patient changeovers. Demographic data, subjective image quality, and injection parameters were collected. Phase two assessed usability via a questionnaire provided to all end-users of both systems (radiographers). RESULTS: Patient changeover times were statistically significantly faster with Centargo (15.4s ± 8.7s vs 53.7s ± 19.6s, p < 0.001). Centargo day-setup times were similar to Stellant (138.1s ± 92s vs 151.8s ± 30.6s, p = 0.33) and end-of-day-disassembly times were significantly slower (60.6s ± 27s vs 17.1s ± 12.9s, p < 0.001). Based on four different scenarios modelling patient throughput, the projected time savings with Centargo over Stellant was 40–63%, with the highest efficiency improvements for higher throughputs and the use of larger contrast medium bottles. Both Centargo and Stellant usability averaged between “Very Easy” and “Easy” in all responses to the questionnaire. There were no instances of interrupted injections due to communication loss or detected air and no insufficient images due to injector performance. No safety issues were identified. CONCLUSION: Centargo was able to demonstrate improved efficiency as compared to Stellant while maintaining injector performance and high usability scores

Shaken or Stirred? The Inconsistencies of Manual Contrast Media Dilution in Endovascular Interventions

MATERIALS AND METHODS: Phase I: Eleven radiological technologists were asked to fill a CM injector 3 times with 50% diluted CM (iopromide 300 mg I/mL). The dilution was injected (12 mL/s) through a Coriolis flowmeter, with CM concentration and total volume calculated. Interoperator, intraoperator, and intraprocedural variations were calculated as coefficients of variability. Contrast media dose reporting accuracy was determined. Phase II: The study was repeated after implementation of a standardized dilution protocol with 5 representative operators. RESULTS: Phase I: The average injected concentration among 11 operators was 68% ± 16% CM (n = 33; range, 43%-98%), as compared with the target of 50% CM. The interoperator variability was 16%, the intraoperator variability was 6% ± 3%, and the intraprocedural variability was 23% ± 19% (range, 5%-67%). This led to overdelivery of CM compared with intended patient dose by 36% on average. Phase II: After standardization, injections averaged 55% ± 4% CM (n = 15; range, 49%-62%), with interoperator variability of 8%, intraoperator variability of 5% ± 1%, and intraprocedural variability of 1.6% ± 0.5% (range, 0.4%-3.7%). CONCLUSIONS: Manual CM dilution can lead to substantial interoperator and intraoperator, as well as intraprocedural variability in injected concentration. This can result in underreporting of administered CM doses to patients. It is recommended that clinics assess their current standard of care regarding CM injections for endovascular interventions and evaluate potential corrective actions if appropriate

Individually Body Weight-Adapted Contrast Media Application in Computed Tomography Imaging of the Liver at 90 kVp

Objectives The aim of the present study was to evaluate the attenuation and image quality (IQ) of a body weight-adapted contrast media (CM) protocol compared with a fixed injection protocol in computed tomography (CT) of the liver at 90 kV. Materials and Methods One hundred ninety-nine consecutive patients referred for abdominal CT imaging in portal venous phase were included. Group 1 (n = 100) received a fixed CM dose with a total iodine load (TIL) of 33 g I at a flow rate of 3.5 mL/s, resulting in an iodine delivery rate (IDR) of 1.05 g I/s. Group 2 (n = 99) received a body weight-adapted CM protocol with a dosing factor of 0.4 g I/kg with a subsequent TIL adapted to the patients' weight. Injection time of 30 seconds was kept identical for all patients. Therefore, flow rate and IDR changed with different body weight. Patients were divided into 3 weight categories; 70 kg or less, 71 to 85 kg, and 86 kg or greater. Attenuation (HU) in 3 segments of the liver, signal-to-noise ratio, and contrast-to-noise ratio were used to evaluate objective IQ. Subjective IQ was assessed by a 5-point Likert scale. Differences between groups were statistically analyzed (P 0.05). Body weight-adapted protocoling led to more homogeneous enhancement of the liver parenchyma compared with a fixed protocol with a mean enhancement per weight category in group 2 of 126.5 +/- 15.8, 128.2 +/- 15.3, and 122.7 +/- 21.2 HU compared with that in group 1 of 139.9 +/- 21.4, 124.6 +/- 24.8, and 116.2 +/- 17.8 HU, respectively. Conclusions Body weight-adapted CM injection protocols result in more homogeneous enhancement of the liver parenchyma at 90 kV in comparison to a fixed CM volume with comparable objective and subjective IQ, whereas overall CM volume can be safely reduced in more than half of patients