Magnetic resonance imaging versus lymphoscintigraphy for the assessment of focal lymphatic transport disorders of the lower limb: first experiences.

PURPOSE: To compare the diagnostic accuracy of magnetic resonance imaging (MR-lymphangiography) and lymphoscintigraphy for assessment of focal lesions of the peripheral lymphatic system. Patients with focal lymphatic transport disorders might benefit from surgi-cal interventions. PATIENTS,
METHODS: We examined by lymphoscintigraphy and MR-lymphangiography a total of 85 lower limbs in 46 consecutive patients (33 women; mean age 41 years; range 9-79 years) presenting with uni- or bilateral lymphedema. MR-lymphangiographies were obtained at isotropic sub-millimeter resolution with a 3.0 Tesla magnet after injection of gadolinium contrast medium. MR-lymphangiography was reviewed by radiologists, whereas lymphoscintigraphy was reviewed by nuclear medicine physicians. The images were examined for localization and distribution of any focal lesions of the lymphatic vessel system. Diagnostic accuracy of the MR-approach was calculated relative to the lymphoscintigraphy gold standard.
RESULTS: There was substantial correlation of results by the two modalities (κ = 0.62). MR-lymphangiography had sensitivity of 68%, specificity of 91%, positive predictive value of 82%, and negative predictive value of 83%.
CONCLUSIONS: Imaging findings of both lymphoscintigraphy and MR-lymphangiography showed good diagnostic accuracy. MR-lymphangiography proved more information about anatomic location of focal lesions of the lymphatic vessels, but use of MR-lymphangiography is currently constrained due to the requirement for off-label subcutaneous injection of gadolinium chelates. Consequently, and due to its superior sensitivity lymphoscintigraphy remains the most common imaging method to assess functional lymphatic disorders of the lower limb.