Thoracic lymph node delineation at dose-reduced (1 mSv) dose-modulated contrast enhanced MDCT: a retrospective pilot study.

PURPOSE: To compare contrast-enhanced low-dose multidetector-row computed tomography (CE-LDCT) of the chest with unenhanced (UN-) LDCT and contrast-enhanced standard-dose CT (CE-SDCT) in regard to the delineation of intrathoracic lymph nodes.

MATERIALS AND

METHODS

Based on the international association for the study of lung cancer (IASLC) grouping of thoracic lymph nodes, two independent radiologists retrospectively assessed lymph node delineation in 9 CE-LDCTs (64 rows, 120 KV, p < 30 mAs/slice) and in 2 control groups of 36 UN-LDCTs and 36 CE-SDCTs, each matched for gender, age, chest/lung diameters, and clinical history. At a significance level of p < 0.025 (Bonferroni-correction for two control groups), two-tailed Chi-square and Fisher's exact tests were applied. For the evaluation of the inter-observer agreement, Cohen's kappa statistics were used.

RESULTS

CE-LDCT delineated lymph node groups significantly more often than UN-LDCT, in general (p < 0.001) and individually in the subcarinal (p < 0.025), the hilar (p < 0.001), and the peripheral lung (p < 0.001) zones. There were no significant differences in lymph node delineation between CE-LDCT and CE-SDCT. Inter-observer agreement was substantial to perfect for all lymph node zones (κ 0.64-1.0). Measurable lymph nodes did not significantly differ in size between cases and controls.

CONCLUSION

At CE-LDCT of the chest, delineation of mediastinal and hilar lymph node groups was superior to UN-LDCT and similar to CE-SDCT. CE-LDCT may be a promising alternative for patients with non-malignant lung disease, unclear chest X-ray findings, or the need for follow-up.