Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine.
Background Iterative reconstruction (IR) is a recent reconstruction algorithm for computed tomography (CT) that can be used instead of the standard algorithm, filtered back projection (FBP), to reduce radiation dose and/or improve image quality. Purpose To evaluate and compare the image quality of low-dose CT of the lumbar spine reconstructed with IR to conventional FBP, without further reduction of radiation dose. Material and Methods Low-dose CT on 55 patients was performed on a Siemens scanner using 120 kV tube voltage, 30 reference mAs, and automatic dose modulation. From raw CT data, lumbar spine CT images were reconstructed with a medium filter (B41f) using FBP and four levels of IR (levels 2-5). Five reviewers scored all images on seven image quality criteria according to the European guidelines on quality criteria for CT, using a five-grade scale. A side-by-side comparison was also performed. Results There was significant improvement in image quality for IR (levels 2-4) compared to FBP. According to visual grading regression, odds ratios of all criteria with 95% confidence intervals for IR2, IR3, IR4, and IR5 were: 1.59 (1.39-1.83), 1.74 (1.51-1.99), 1.68 (1.46-1.93), and 1.08 (0.94-1.23), respectively. In the side-by-side comparison of all reconstructions, images with IR (levels 2-4) received the highest scores. The mean overall CTDIvolwas 1.70 mGy (SD 0.46; range, 1.01-3.83 mGy). Image noise decreased in a linear fashion with increased strength of IR. Conclusion Iterative reconstruction at levels 2, 3, and 4 improves image quality of low-dose CT of the lumbar spine compared to FPB.
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.
Muhammed
M
Alshamari
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.|2 Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Lund University, Sweden.
Mats
M
Geijer
3 Department of Medical Physics, School of Medical Sciences, Örebro University, Örebro, Sweden.
Eva
E
Norrman
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.
Mats
M
Lidén
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.
Wolfgang
W
Krauss
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.
Johan
J
Jendeberg
4 Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University, Örebro, Sweden.
Anders
A
Magnuson
1 Department of Radiology, School of Medical Sciences, Örebro University, Örebro, Sweden.
Håkan
H
Geijer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
X-ray computed tomography (CT); image manipulation/reconstruction; lumbar vertebrae; radiation dosage; spine