Can iterative reconstruction algorithms replace tube loading compensation in low kVp hepatic CT? Subjective versus...

Area of Science:

• Radiology
• Medical Imaging
• Nephrology

Background:

• Lowering peak kilovoltage (kVp) in hepatic computed tomography (CT) reduces contrast medium doses, crucial for patients at risk of contrast-induced acute kidney injury (CI-AKI).
• This dose reduction strategy increases image noise, necessitating image quality preservation techniques.
• Tube loading compensation (TLC) or iterative reconstruction (IR) algorithms are potential methods to control noise in low-kVp CT imaging.

Purpose of the Study:

• To evaluate and compare the image quality of 80 kVp hepatic CT protocols.
• The study specifically compared 80 kVp CT with TLC and filtered back projection (FBP) against 80 kVp with no TLC (No-TLC) and IR algorithms (SAFIRE 3 and 5).
• The evaluation focused on patients with an estimated glomerular filtration rate (eGFR) below 45 mL/min.

Main Methods:

• Forty patients with a BMI of 18-32 kg/m² underwent hepatic CT using both protocols after a 300 mg I/kg contrast medium injection.
• Key image quality parameters assessed included hepatic attenuation, image noise, enhancement, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR).
• Subjective image quality was evaluated using visual grading scores.

Main Results:

• Comparing TLC/FBP with No-TLC/IR-S5, no significant differences were found in hepatic attenuation, image noise, enhancement, SNR, or CNR.
• However, No-TLC/IR-S3 demonstrated higher image noise and lower SNR and CNR compared to TLC/FBP.
• Subjective image quality scores were significantly lower for the IR-S5 images compared to TLC/FBP.

Conclusions:

• Combining 80 kVp hepatic CT for reduced contrast dose in CI-AKI-risk patients with IR algorithms and unchanged tube loading does not achieve adequate diagnostic image quality.
• The findings suggest that current IR algorithms, when used without TLC at 80 kVp, may not sufficiently mitigate noise to maintain diagnostic standards.
• Optimizing low-dose CT protocols requires further investigation to balance contrast dose reduction with acceptable image quality for clinical use.