Chest CT in patients after lung transplantation: A retrospective analysis to evaluate impact on image quality and radiation dose using spectral filtration tin-filtered imaging

Alexander Wressnegger; Helmut Prosch; Bernhard Moser; Walter Klepetko; Peter Jaksch; Christopher Lambers; Konrad Hoetzenecker; Christian Schestak; Albert De Bettignies; Lucian Beer; Georg Apfaltrer; Helmut Ringl; Paul Apfaltrer

doi:10.1371/journal.pone.0228376

Chest CT in patients after lung transplantation: A retrospective analysis to evaluate impact on image quality and radiation dose using spectral filtration tin-filtered imaging

PLoS One. 2020 Feb 5;15(2):e0228376. doi: 10.1371/journal.pone.0228376. eCollection 2020.

Affiliations

¹ Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
² Division of Surgery, Department of Thoracic Surgery, Medical University Vienna, Vienna, Austria.
³ Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria.
⁴ Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.

Abstract

Objectives: The purpose of this study was to investigate the impact of a 150kV spectral filtration chest imaging protocol (Sn150kVp) combined with advanced modeled iterative reconstruction (ADMIRE) on radiation dose and image quality in patients after lung-transplantation.

Methods: This study included 102 patients who had unenhanced chest-CT examinations available on both, a second-generation dual-source CT (DSCT) using standard protocol (100kVp, filtered-back-projection) and, on a third-generation DSCT using Sn150kVp protocol with ADMIRE. Signal-to-noise-ratio (SNR) was measured in 6 standardized regions. A 5-point Likert scale was used to evaluate subjective image quality. Radiation metrics were compared.

Results: The mean time interval between the two acquisitions was 1.1±0.7 years. Mean-volume-CT-dose-index, dose-length-product and effective dose were significantly lower for Sn150kVp protocol (2.1±0.5mGy;72.6±16.9mGy*cm;1.3±0.3mSv) compared to 100kVp protocol (6.2±1.8mGy;203.6±55.6mGy*cm;3.7±1.0mSv) (p<0.001), equaling a 65% dose reduction. All studies were considered of diagnostic quality. SNR measured in lung tissue, air inside trachea, vertebral body and air outside the body was significantly higher in 100kVp protocol compared to Sn150kVp protocol (12.5±2.7vs.9.6±1.5;17.4±3.6vs.11.8±1.8;0.7±0.3vs.0.4±0.2;25.2±6.9vs.14.9±3.3;p<0.001). SNR measured in muscle tissue was significantly higher in Sn150kVp protocol (3.2±0.9vs.2.6±1.0;p<0.001). For SNR measured in descending aorta there was a trend towards higher values for Sn150kVp protocol (2.8±0.6 vs. 2.7±0.9;p = 0.3). Overall SNR was significantly higher in 100kVp protocol (5.0±4.0vs.4.0±4.0;p<0.001). On subjective analysis both protocols achieved a median Likert rating of 1 (25th-75th-percentile:1-1;p = 0.122). Interobserver agreement was good (intraclass correlation coefficient = 0.73).

Conclusions: Combined use of 150kVp tin-filtered chest CT protocol with ADMIRE allows for significant dose reduction while maintaining highly diagnostic image quality in the follow up after lung transplantation when compared to a standard chest CT protocol using filtered back projection.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Algorithms
Female
Humans
Image Processing, Computer-Assisted / methods*
Lung Diseases / diagnostic imaging*
Lung Diseases / surgery
Lung Transplantation / methods*
Male
Middle Aged
Radiation Dosage
Radiographic Image Enhancement / instrumentation*
Radiographic Image Enhancement / methods
Radiographic Image Interpretation, Computer-Assisted / methods*
Radiography, Thoracic / methods*
Retrospective Studies
Signal-To-Noise Ratio
Tin
Tomography, X-Ray Computed / methods*

Substances

Tin

Grants and funding

This study was supported by the Medical Scientific Fund of the Mayor of the City of Vienna. This study was supported by Siemens Healthineers (Grant Number: FA771B1201 to PA).