Less radiation, same quality: contrast-enhanced multi-detector computed tomography investigation of thoracic lymph nodes with one milli-sievert
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Mediastinal, hilar, and peripheral pulmonary lymphadenopathy is a hallmark sign of different benign and malignant diseases of the chest. Contrast-enhanced (CE) chest CT is a test frequently applied to examine thoracic lymph node zones. We attempted to find out whether mediastinal, hilar, and peripheral lymph nodes delineate equally in CE chest CT with reduced dose (CE-LDCT, about 1 mSv) when compared with accepted standard CE chest CT (CE-SDCT).
Materials and methods
In this ethics committee-approved, mono-institutional, retrospective (20 months) matched case–control study, two independent, blinded observers compared measurable lymph node delineation (yes–no) in six different International Association for the Study of Lung Cancer (IASLC) zones (upper mediastinal, aortopulmonary, subcarinal, lower mediastinal, hilar, peripheral) between 62 CE-LDCT cases and 124 CE-SDCT controls (respective tube charge, 100, 120 KVp, computed tomography dose index, 1.66 ± 0.51, 5.36 ± 2.24 mGy, automatic exposure control-modulated 64-row multi-detector chest CT with iterative image reconstruction). Individual matching for gender (53% female), age (53 ± 19 years), body height, weight, anterior–posterior and transverse diameters of chest and lung ruled out pre-test confounders. Lymph node size (cut-off value, 1 cm) was a potential post-test confounder. Two-tailed T test and Chi-square test were significant for p < 0.05.
Measurable lymph nodes delineated equally in cases (261/372 IASLC zones, 70%; 280/372, 75%) and controls (528/744, 71%; 519/744, 70%; no significant differences, power 90%). One observer delineated significantly more peripheral zone lymph nodes in cases (35/62) than in controls (43/124); there were no significant differences otherwise. Lymph node size did not differ significantly; effective dose was 1.0 ± 0.3 mSv in cases and 3.4 ± 1.5 mSv in controls.
CE-LDCT with about 1 mSv demonstrated equal delineation of thoracic lymph nodes when compared with accepted standard CE-SDCT.
KeywordsChest CT Low dose Contrast media Lymph node delineation IASLC classification
Automatic exposure control
Body mass index
Intravenous contrast enhancement or intravenously contrast-enhanced
Contrast-enhanced highly dose-saving computed tomography of the chest
Contrast-enhanced computed tomography of the chest with standard dose
Computed tomography dose index
Dose length product
Conversion factor of EUR 16262 EN
International Association for the Study of Lung Cancer
Iterative image reconstruction
Highly dose-saving computed tomography of the chest
Multi-detector row-computed tomography
Picture archiving and communication system
Computed tomography of the chest with standard dose
This manuscript includes results of doctoral thesis work in preparation by Larissa Marwitz at the Faculty of Medicine of the University of Munich (“Ludwig-Maximilians-Universität”, LMU), Germany. Authors acknowledge the kind support of their research activities by Professors Maximilian F. Reiser and Jens Ricke, Directors of the Department of Radiology of the Faculty of Medicine of the University of Munich (“Ludwig-Maximilians-Universität”, LMU), Germany.
Compliance with ethical standards
Conflict of interest
All authors declare that there is no conflict of interest.
This was a retrospective study. It was performed in accordance with the Declaration of Helsinki and approved by the local ethics committee. This article does not contain any studies with animals.
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