Advanced

Simulated Dose Reduction for Abdominal CT With Filtered Back Projection Technique: Effect on Liver Lesion Detection and Characterization

Aho Fält, Tobias LU ; Söderberg, Marcus LU ; Hörberg, Lisa LU ; Christoffersen, Christina ; Lång, Kristina LU ; Abul-Kasim, Kasim LU and Leander, Peter LU (2019) In American Journal of Roentgenology 212(1). p.84-93
Abstract
OBJECTIVE. Previous studies have shown the possibility to reduce radiation dose in abdominal CT by 25–50% without negatively affecting detection of liver lesions. How radiation dose reduction affects characterization of liver metastases is not as well known. The objective of this study was to investigate how different levels of simulated dose reduction affect the detection and characterization of liver lesions, primarily hypovascular metastases. A secondary objective was to analyze the relationship between the lesion size and contrast-to-noise ratio (CNR) and the detection rate.

MATERIALS AND METHODS. Thirty-nine patients (19 with metastases and 20 without) were retrospectively selected. The following radiation dose levels (DLs)... (More)
OBJECTIVE. Previous studies have shown the possibility to reduce radiation dose in abdominal CT by 25–50% without negatively affecting detection of liver lesions. How radiation dose reduction affects characterization of liver metastases is not as well known. The objective of this study was to investigate how different levels of simulated dose reduction affect the detection and characterization of liver lesions, primarily hypovascular metastases. A secondary objective was to analyze the relationship between the lesion size and contrast-to-noise ratio (CNR) and the detection rate.

MATERIALS AND METHODS. Thirty-nine patients (19 with metastases and 20 without) were retrospectively selected. The following radiation dose levels (DLs) were simulated: 100% (reference level), 75%, 50%, and 25%. Five readers were asked to mark liver lesions and rate the probability of malignancy on a 5-grade Likert scale. Noninferiority analysis using the jackknife free-response ROC (JAFROC) method was performed as well as direct comparison of detection rates and grades.

RESULTS. JAFROC analysis showed noninferior detection and characterization of metastases at DL75 as compared with DL100. However, the number of benign lesions and false-positive localizations rated as “suspected malignancy” was significantly higher at DL75.

CONCLUSION. Radiation dose can be reduced by 25% without negatively affecting diagnosis of hypovascular liver metastases. Characterization of benign lesions, however, is impaired at DL75, which may lead to unnecessary follow-up examinations. Finally, increased image noise seems to affect the detection of small lesions to a degree that cannot be explained solely by the reduction in CNR.


(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
American Journal of Roentgenology
volume
212
issue
1
pages
84 - 93
publisher
American Roentgen Ray Society
external identifiers
  • pmid:30299999
  • scopus:85058883697
ISSN
0361-803X
DOI
10.2214/AJR.17.19441
language
English
LU publication?
yes
id
c0fc5aa9-b8f0-491a-bc5a-8c04e6df22d0
date added to LUP
2018-11-09 13:51:04
date last changed
2020-02-26 07:05:55
@article{c0fc5aa9-b8f0-491a-bc5a-8c04e6df22d0,
  abstract     = {OBJECTIVE. Previous studies have shown the possibility to reduce radiation dose in abdominal CT by 25–50% without negatively affecting detection of liver lesions. How radiation dose reduction affects characterization of liver metastases is not as well known. The objective of this study was to investigate how different levels of simulated dose reduction affect the detection and characterization of liver lesions, primarily hypovascular metastases. A secondary objective was to analyze the relationship between the lesion size and contrast-to-noise ratio (CNR) and the detection rate.<br/><br/>MATERIALS AND METHODS. Thirty-nine patients (19 with metastases and 20 without) were retrospectively selected. The following radiation dose levels (DLs) were simulated: 100% (reference level), 75%, 50%, and 25%. Five readers were asked to mark liver lesions and rate the probability of malignancy on a 5-grade Likert scale. Noninferiority analysis using the jackknife free-response ROC (JAFROC) method was performed as well as direct comparison of detection rates and grades.<br/><br/>RESULTS. JAFROC analysis showed noninferior detection and characterization of metastases at DL75 as compared with DL100. However, the number of benign lesions and false-positive localizations rated as “suspected malignancy” was significantly higher at DL75.<br/><br/>CONCLUSION. Radiation dose can be reduced by 25% without negatively affecting diagnosis of hypovascular liver metastases. Characterization of benign lesions, however, is impaired at DL75, which may lead to unnecessary follow-up examinations. Finally, increased image noise seems to affect the detection of small lesions to a degree that cannot be explained solely by the reduction in CNR.<br/><br/><br/>},
  author       = {Aho Fält, Tobias and Söderberg, Marcus and Hörberg, Lisa and Christoffersen, Christina and Lång, Kristina and Abul-Kasim, Kasim and Leander, Peter},
  issn         = {0361-803X},
  language     = {eng},
  number       = {1},
  pages        = {84--93},
  publisher    = {American Roentgen Ray Society},
  series       = {American Journal of Roentgenology},
  title        = {Simulated Dose Reduction for Abdominal CT With Filtered Back Projection Technique: Effect on Liver Lesion Detection and Characterization},
  url          = {http://dx.doi.org/10.2214/AJR.17.19441},
  doi          = {10.2214/AJR.17.19441},
  volume       = {212},
  year         = {2019},
}