Accurate tissue characterization in low‐dose CT imaging with pure iterative reconstruction. Issue 2 (13th October 2016)

• Record Type: Journal Article
• Authors: Murphy, Kevin P; McLaughlin, Patrick D; Twomey, ‎Maria; Chan, Vincent E; Moloney, Fiachra; Fung, Adrian J; Chan, Faimee E; Kao, Tafline; O'Neill, Siobhan B; Watson, Benjamin; O'Connor, Owen J; Maher, Michael M
• Is Part Of: Journal of medical imaging and radiation oncology. Volume 61:Issue 2(2017:Apr.)
• Page Start: 190
• Page End: 196
• Publication Date: 2016-10-13
• Subjects: computed tomography -- Hounsfield units -- image reconstruction -- iterative reconstruction -- radiation; Radiology, Medical -- Periodicals; Radiology, Medical -- Australasia -- Periodicals; 616.0757
• DOI: 10.1111/1754-9485.12546
• Languages: English
• ISSNs: 1754-9477

Abstract

Abstract: Introduction: We assess the ability of low‐dose hybrid iterative reconstruction (IR) and 'pure' model‐based IR (MBIR) images to maintain accurate Hounsfield unit (HU)‐determined tissue characterization. Methods: Standard‐protocol (SP) and low‐dose modified‐protocol (MP) CTs were contemporaneously acquired in 34 Crohn's disease patients referred for CT. SP image reconstruction was via the manufacturer's recommendations (60% FBP, filtered back projection; 40% ASiR, Adaptive Statistical iterative Reconstruction; SP‐ASiR40). MP data sets underwent four reconstructions (100% FBP; 40% ASiR; 70% ASiR; MBIR). Three observers measured tissue volumes using HU thresholds for fat, soft tissue and bone/contrast on each data set. Analysis was via SPSS. Results: Inter‐observer agreement was strong for 1530 datapoints ( rs > 0.9). MP‐MBIR tissue volume measurement was superior to other MP reconstructions and closely correlated with the reference SP‐ASiR40 images for all tissue types. MP‐MBIR superiority was most marked for fat volume calculation – close SP‐ASiR40 and MP‐MBIR Bland–Altman plot correlation was seen with the lowest average difference (336 cm 3 ) when compared with other MP reconstructions. Conclusions: Hounsfield unit‐determined tissue volume calculations from MP‐MBIR images resulted in values comparable to SP‐ASiR40 calculations and values that are superior to MP‐ASiR images. Accuracy of estimation of volume of tissues (e.g. fat) using segmentation software on low‐dose CT images appears optimal when reconstructed with pure IR.