80-kV_p hepatic CT to reduce contrast medium dose in azotemic patients: a feasibility study

Abstract

Background Low peak kilovoltage (kVp) computed tomography (CT) may be used to reduce contrast medium doses in patients at risk of contrast medium-induced acute kidney injury if image noise can be controlled by increasing X-ray tube loading (mAs). Purpose To evaluate objective and subjective image quality in 80-kVp CT with reduced contrast medium dose and compensated mAs for unchanged image noise in patients with estimated glomerular filtration rate <45 mL/min compared with the standard 120-kVp protocol. Material and Methods 80-kVp CT with 300 mg I/kg in 40 patients (body mass index 18–32 kg/m2, glomerular filtration rate <45 mL/min) and 120-kVp CT with 500 mg I/kg in 40 patients (body mass index = 17–30 kg/m2, glomerular filtration rate ≥45 mL/min) was compared on mean hepatic attenuation, image noise, contrast medium enhancement, signal-to-noise ratio, contrast-to-noise ratio, effective radiation dose, and subjective image quality. Results There were no significant differences regarding median hepatic post-contrast attenuation, image noise, contrast medium enhancement, signal-to-noise ratio, contrast-to-noise ratio, or effective dose between the 80-kVp and 120-kVp cohorts: 114/110 HU; 14/14 HU; 57/53 HU; 8.0/7.4; 3.8/3.5; and 5.3/5.9 mSv, respectively. However, subjective image visual grading showed statistically significantly inferior scores for 80 kVp for six of eight items. After exclusion of seven inferior examinations not caused by the chosen kVp technique, only three items showed inferior scores for 80 kVp. Only 5% of gradings regarding overall image quality were <3 of 5 points. Conclusion Despite lower subjective image quality, objective data indicate that 80-kVp CT with reduced contrast medium doses and compensated mAs may have the potential to provide satisfactory diagnostic quality in patients with body mass index <30 kg/m2, which could benefit patients at risk of contrast medium-induced acute kidney injury.

Finding the optimal tube current and iterative reconstruction strength in liver imaging; two needles in one haystack

“…A number of studies have evaluated the possibility to reduce radiation dose in abdominal imaging [ 23 , 29 – 33 ]. To the best of our knowledge, this is the first study comparing different radiation doses and IR strengths in abdominal imaging, within the same patient by using reconstruction software.…”

“…Establishing the objective image quality with SNR and CNR seems rather straightforward. Although, when searching for reliable thresholds, a wide variety of values is found in the literature, all presumed to be of diagnostic image quality, and no clear cut-off values have been established [ 33 – 37 ]. In addition, previous literature states that both SNR and CNR might not encompass the complete appreciation of image quality [ 38 , 39 ].…”

Revised Swedish guidelines on intravenous iodine contrast medium-induced acute kidney injury 2022: A summary

“… Patients with stable hemodynamics and renal function, and a GFR of 30–44 or 45–59 mL/min/1.73 m 2 and ≥2 non-renal risk factors are no longer considered at risk of CI-AKI provided that the gram-iodine/GFR ABS ratio can be kept <0.5. To facilitate a low ratio, the use of low-kilovoltage CT technique is recommended (20–26). CM is no longer considered to be a significant risk factor for the loss of RRF in patients undergoing dialysis.…”