Abstract
OBJECTIVE: To investigate the diagnostic value of combined non-contrast MR lymphangiography (NCMRL) and (99)TC(m)-DX lymphoscintigraphy in systemic lupus erythematosus(SLE) and rheumatoid arthritis(RA) with lymphatic system involvement. METHODS: A retrospective analysis was conducted on the clinical and imaging data of 25 SLE patients with lymphatic system involvement and 18 RA patients with lymphatic system involvement. All patients underwent NCMRL and (99)TC(m)-DX lymphoscintigraphy examinations. The chi-square test or Fisher’s exact test was used to analyze the distribution differences of abnormal lymphatic system signs in NCMRL and ⁹⁹Tcᵐ-DX lymphangiography between the two groups of patients. McNemar’s test was used to compare the abnormal lymphatic vessel signs detected by the two imaging modalities in 43 patients with SLE or RA with lymphatic system involvement. The Kappa test was applied to evaluate the diagnostic consistency of the two imaging modalities in identifying abnormal lymphatic vessels in these patients. P < 0.05 was statistically significant. RESULTS: MRL showed that the incidence of thoracic duct outlet obstruction in SLE patients with lymphatic system involvement (25, 100.0%) was significantly higher than that in RA patients with lymphatic system involvement (6, 33.3%) (P = 0.000). In ⁹⁹Tcᵐ - DX lymphoscintigraphy, the incidence of chylous effusion in SLE patients with lymphatic system involvement (22, 88.0%) was significantly higher than that in RA patients with lymphatic system involvement (4, 22.2%), while the incidence of limb lymphedema in RA patients with lymphatic system involvement (14, 77.8%) was significantly higher than that in SLE patients with lymphatic system involvement (4 cases, 20.0%) (P = 0.000). There was no statistically significant difference (P > 0.05) in the detection rates of obstruction of the thoracic duct outlet, tortuous dilation of the thoracic segment of the thoracic duct, abnormality of the bronchial mediastinum, and dilation of the iliac lymphatic vessels and lumbar trunk between the two examinations. The Kappa values were rated as follows: almost perfect (1.000), good (0.788), moderate (0.482), and fair agreement (0.256). CONCLUSION: ⁹⁹Tcᵐ-DX lymphoscintigraphy dynamically reflects lymphatic reflux and identifies lymphedema and chylous effusion in SLE and RA patients with lymphatic involvement, but has low spatial resolution. NCMRL clearly displays systemic lymphatic vessel abnormalities and surrounding tissue conditions, yet cannot confirm chylous effusions or localize active chyle leakage. Combined use of the two modalities provides comprehensive imaging information for the clinical diagnosis of SLE and RA with lymphatic system involvement.