Less radiation, same quality: contrast-enhanced multi-detector computed tomography investigation of thoracic lymph nodes with one milli-sievert

PURPOSE: 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. RESULTS: 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. CONCLUSION: CE-LDCT with about 1 mSv demonstrated equal delineation of thoracic lymph nodes when compared with accepted standard CE-SDCT.

• Mueller-Lisse, U. G.
• Marwitz, L.
• Tufman, A.
• Huber, R. M.
• Zimmermann, H. A.
• Walterham, A.
• Wirth, S.
• Paolini, M.