Assessment of image quality in abdominal CT: potential dose reduction with model-based iterative reconstruction

Abstract

PurposeTo estimate potential dose reduction in abdominal CT by visually comparing images reconstructed with filtered back projection (FBP) and strengths of 3 and 5 of a specific MBIR.Material and methodsA dual-source scanner was used to obtain three data sets each for 50 recruited patients with 30, 70 and 100% tube loads (mean CTDIvol 1.9, 3.4 and 6.2 mGy). Six image criteria were assessed independently by five radiologists. Potential dose reduction was estimated with Visual Grading Regression (VGR).ResultsComparing 30 and 70% tube load, improved image quality was observed as a significant strong effect of log tube load and reconstruction method with potential dose reduction relative to FBP of 22–47% for MBIR strength 3 (p < 0.001). For MBIR strength 5 no dose reduction was possible for image criteria 1 (liver parenchyma), but dose reduction between 34 and 74% was achieved for other criteria. Interobserver reliability showed agreement of 71–76% (κw 0.201–0.286) and intra-observer reliability of 82–96% (κw 0.525–0.783).ConclusionMBIR showed improved image quality compared to FBP with positive correlation between MBIR strength and increasing potential dose reduction for all but one image criterion.Key Points• MBIR’s main advantage is its de-noising properties, which facilitates dose reduction.• MBIR allows for potential dose reduction in relation to FBP.• Visual Grading Regression (VGR) produces direct numerical estimates of potential dose reduction.• MBIR strengths 3 and 5 dose reductions were 22–34 and 34–74%.• MBIR strength 5 demonstrates inferior performance for liver parenchyma.

Assessment of image quality in abdominal computed tomography: Effect of model-based iterative reconstruction, multi-planar reconstruction and slice thickness on potential dose reduction

“…Images acquired at tube loads 42 mAs and 98 mAs are included in the present assessment as previous evaluation indicated no significant improvement in image quality between 98 mAs and 140 mAs [8]. Twenty-five patients who underwent a clinically indicated non-enhanced abdominal CT were included, and demographic data (age, height, mass) were recorded.…”

“…The diagnostic performance and effect of model-based iterative reconstruction (MBIR) on different aspects of image quality and potential dose reductions has been studied by several peers [8][9][10][11][12]. However, due to increase in image noise, dose reduction impairs the diagnostic confidence as depiction of low-contrast lesions in abdominal imaging is compromised.…”

“…Since reduction of noise allows for dose reduction, this is of particular interest in optimization. Previous visual evaluation performed on advanced modeled iterative reconstruction (ADMIRE) strength 3 (AD3) and 5 (AD5) showed a preference for AD3 over AD5 [8]. To determine the desired clinical image quality, an evaluation of both subjective and objective image quality parameters is a prerequisite when a new image reconstruction technique is introduced into the clinical routine [12].…”

Performance Evaluation of Two Iterative Reconstruction Algorithms--MBIR and ASIR, in Low Radiation Dose and Low Contrast Dose Abdominal CT in Children

“…MBIR has been applied in clinical practice; through the analysis of the existing literatures, MBIR can greatly reduce noise and dramatically improve image quality [11][12][13][14][15][16][17][18], so, we evaluated 0.625mm thin slice image quality instead of routine 5mm images (with ASIR40%) to obtain more details. In addition, it has been reported that MBIR can improve the recognition of necrotic lesions in children and is suitable for displaying the density difference of soft tissue [20].…”

“…Iterative reconstruction (IR) has been used in the "double low" CT to reduce image noise and to meet the diagnostic requirements and has been applied to CT applications in chest, abdomen, blood vessel and other areas [5][6][7][8][9][10][11]. In addition, relevant studies have shown that the more sophisticated full model-based iterative reconstruction (MBIR) algorithm is more powerful than the adaptive statistical iterative reconstruction (ASIR) in image noise reduction [12][13][14][15][16][17]. So far, most of the "double-low" CT studies have been focused on blood vessel(s) [3,4,6,8], or in adults, and there are only few reports on CECT in children's abdomen, which often requires higher x-ray doses than other body regions [18].…”