Model-based Iterative Reconstruction: Effect on Patient Radiation Dose and Image Quality in Pediatric Body CT

• Published in: Radiology Vol. 270; no. 2; pp. 526 - 534
• Main Authors: Smith, Ethan A., Dillman, Jonathan R., Goodsitt, Mitchell M., Christodoulou, Emmanuel G., Keshavarzi, Nahid, Strouse, Peter J.
• Format: Journal Article
• Language: English
• Published: United States Radiological Society of North America 01.02.2014
• Subjects: Adolescent; Algorithms; Child; Child, Preschool; Humans; Infant; Neoplasms - diagnostic imaging; Original Research; Phantoms, Imaging; Radiation Dosage; Radiographic Image Interpretation, Computer-Assisted; Radiography, Abdominal; Radiography, Thoracic; Retrospective Studies; Tomography, X-Ray Computed - methods; Young Adult
• ISSN: 0033-8419; 1527-1315; 1527-1315
• DOI: 10.1148/radiol.13130362

To retrospectively compare image quality and radiation dose between a reduced-dose computed tomographic (CT) protocol that uses model-based iterative reconstruction (MBIR) and a standard-dose CT protocol that uses 30% adaptive statistical iterative reconstruction (ASIR) with filtered back projection. Institutional review board approval was obtained. Clinical CT images of the chest, abdomen, and pelvis obtained with a reduced-dose protocol were identified. Images were reconstructed with two algorithms: MBIR and 100% ASIR. All subjects had undergone standard-dose CT within the prior year, and the images were reconstructed with 30% ASIR. Reduced- and standard-dose images were evaluated objectively and subjectively. Reduced-dose images were evaluated for lesion detectability. Spatial resolution was assessed in a phantom. Radiation dose was estimated by using volumetric CT dose index (CTDI(vol)) and calculated size-specific dose estimates (SSDE). A combination of descriptive statistics, analysis of variance, and t tests was used for statistical analysis. In the 25 patients who underwent the reduced-dose protocol, mean decrease in CTDI(vol) was 46% (range, 19%-65%) and mean decrease in SSDE was 44% (range, 19%-64%). Reduced-dose MBIR images had less noise (P > .004). Spatial resolution was superior for reduced-dose MBIR images. Reduced-dose MBIR images were equivalent to standard-dose images for lungs and soft tissues (P > .05) but were inferior for bones (P = .004). Reduced-dose 100% ASIR images were inferior for soft tissues (P < .002), lungs (P < .001), and bones (P < .001). By using the same reduced-dose acquisition, lesion detectability was better (38% [32 of 84 rated lesions]) or the same (62% [52 of 84 rated lesions]) with MBIR as compared with 100% ASIR. CT performed with a reduced-dose protocol and MBIR is feasible in the pediatric population, and it maintains diagnostic quality.