Abstract
ObjectiveTo investigate differences between reconstruction algorithms in quantitative perfusion values and time-attenuation curves in computed tomography perfusion (CTP) examinations of the upper abdomen. MethodsTwenty-six CTP examinations were reconstructed with filtered back projection and an iterative reconstruction algorithm, advanced modeled iterative reconstruction (ADMIRE), with different levels of noise-reduction strength. Using the maximum-slope model, quantitative measurements were obtained: blood flow (mL/min/100 mL), blood volume (mL/100 mL), time to peak (s), arterial liver perfusion (mL/100 mL/min), portal venous liver perfusion (mL/100 mL/min), hepatic perfusion index (%), temporal maximum intensity projection (Hounsfield units (HU)) and temporal average HU. Time-attenuation curves for seven sites (left liver lobe, right liver lobe, hepatocellular carcinoma, spleen, gastric wall, pancreas, portal vein) were obtained. Mixed-model analysis was used for statistical evaluation. Image noise and the signal:noise ratio (SNR) were compared between four reconstructions, and statistical analysis of these reconstructions was made with a related-samples Friedman’s two-way analysis of variance by ranks test. ResultsThere were no significant differences for quantitative measurements between the four reconstructions for all tissues. There were no significant differences between the AUC values of the time-attenuation curves between the four reconstructions for all tissues, including three automatic measurements (portal vein, aorta, spleen). There was a significant difference in image noise and SNR between the four reconstructions. ConclusionsADMIRE did not affect the quantitative measurements or time-attenuation curves of tissues in the upper abdomen. The image noise was lower, and the SNR higher, for iterative reconstructions with higher noise-reduction strengths.
Highlights
Computed tomography perfusion (CTP) has been used since 1991, but broad application of this modality in clinical workflow has not been implemented
We investigated if there are differences between quantitative measurements and the time-attenuation curves obtained in different tissues in reconstructions made with filtered back projection (FBP) and advanced modeled iterative reconstruction (ADMIRE) using a system from Siemens Healthcare
There was no significant difference between the quantitative measurements of blood flow (BF), blood volume (BV), to peak (TP), arterial liver perfusion (ALP), portal venous liver perfusion (PVP), hepatic perfusion index (HPI) or temporal average (TAVG) between the four reconstructions in any tissue (Fig. 4)
Summary
Computed tomography perfusion (CTP) has been used since 1991, but broad application of this modality in clinical workflow has not been implemented This is due (at least in part) to: (i) the initially limited area that could be examined; (ii) quality issues because of motion artifacts from breathing; (iii) the high radiation doses rendered by these studies compared with standard CT. Technological developments in CT have made it possible to increase the scan length for CTP, thereby enabling coverage of the entire trunk They have provided effective ways to eliminate motion artefacts that are otherwise problematic in CTP examinations of this body area. Comparative studies of visual and quantitative assessments of CTP images are, warranted
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