Individualized Protocol Saves Contrast Dose in Liver CT

Background

Vulnerable patients with preexisting renal insufficiency or diabetes may have a higher risk of developing contrast-induced acute kidney injury (CI-AKI). Reducing CI-AKI incidence can be achieved by reducing iodinated contrast dose. Personalized body weight-adapted contrast injection protocol software such as P3Tᵀᴹ (Bayer) has already shown to be effective: it is able to reduce contrast dose without compromising diagnostic attenuation (Kok 2015, Mihl 2016). However, its application has not yet been evaluated for liver imaging

P3Tᵀᴹ is an individualized contrast medium injection software: It adapts iodine delivery rate (IDR) and total iodine load based upon a nonlinear relationship between patient weight and scan duration, while still achieving a diagnostic scan.

Conclusion

Contrast medium dose was reduced by an average of 14.8mL with the individualized ICM injection protocol compared to the standard protocol for all groups. With regard to body weight subgroups, contrast dose reduction was 8.51mL for patients ≤50kg, 10.86 for patients >50kg and <65 kg as well as 11.95mL for patients ≥65kg body weight.
The method’s is easy-to-use characteristics provide individualized contrast medium injection protocols even under special and clinical research requirements, note the authors.

Value Proposition

In contrast enhanced liver CT, using P3Tᵀᴹ based on patient weight effectively reduced contrast medium dose without affecting image quality.

Methods

This prospective, randomized, single-center study compares the performance of dual phase enhanced liver CT with an individualized ICM injection protocol using P3Tᵀᴹ versus a standard weight-based ICM injection with a dose of 1.5mL/kg body weight.

• 324 cases, all receiving a 64-detector row liver CT (120kV, 250mAs), both unenhanced and enhanced
• Iopromide (Ultravist®) with a concentration of 300mgI/mL at a flow rate of 3mL/s.
• Contrast medium injection rate and contrast medium concentration remained fixed. The only changed parameter was contrast medium dose.

Image analysis was done quantitatively using CT values and ΔHU (difference in CT values between enhanced and unenhanced CT) of the liver parenchyma and liver parenchyma during the hepatic artery phase (HAP) and the portal venous phase (PVP), as well as contrast medium required between the two groups.
Image analysis was performed qualitatively by two radiologists, both with a minimum experience of 15 years. Both were blinded to clinical data.

Results in Detail

Quantitative measurements

• No statistical difference during the hepatic artery phase (HAP) for CT values of the liver parenchyma and liver parenchyma ∆HU (difference in CT values between enhanced and unenhanced CT).
• Statistical differences during the portal venous phase (PVP) in CT values for liver parenchyma and the portal vein, as well as liver parenchyma ∆HU and for contrast medium required between the two groups.

Qualitative measurements

• No obvious differences between the P3T and the standard dose groups regarding anatomical structures.
• Both radiologists substantially agreed in grading tumor conspicuity.

Contrast medium doses

The mean contrast medium doses used in the three weight-based subgroups were:

Mean contrast medium dose in the weight-based subgroups

Lesion Detection

• Liver CT with the individualized contrast protocol led to the detection of 31 lesions in 23 patients.
• Liver CT with the standard contrast protocol led to the detection of 27 lesions in the 15 patients with confirmed hepatocellular carcinoma (HCC).
• There was no statistical difference in the tumor-liver contrast between the two groups.