80-kVp hepatic CT to reduce contrast medium dose in azotemic patients: a feasibility study. (April 2020)

• Record Type: Journal Article
• Authors: Holmquist, Fredrik; Söderberg, Marcus; Nyman, Ulf; Fält, Tobias; Siemund, Roger; Geijer, Mats
• Is Part Of: Acta radiologica. Volume 61:Number 4(2020)
• Page Start: 441
• Page End: 449
• Publication Date: 2020-04
• Subjects: Computed tomography -- contrast media -- acute kidney injury -- liver -- filtered back-projection -- image noise -- low tube voltage; Radiology, Medical -- Periodicals; Radiography, Medical -- Periodicals; Radiotherapy -- Periodicals; 616.0757
• DOI: 10.1177/0284185119866807
• Languages: English
• ISSNs: 0284-1851

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/m 2, glomerular filtration rate <45 mL/min) and 120-kVp CT with 500 mg I/kg in 40 patients (body mass index = 17–30 kg/m 2, 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/m 2, which could benefit patients at risk of contrast medium-induced acute kidney injury.