Indocyanine green lymphography is superior to lymphoscintigraphy in imaging diagnosis of secondary lymphedema of the lower limbs

Objective: Lymphedema is commonly viewed as difficult to treat, but lymphaticovenous anastomosis applied early after onset can be curative in some cases. Therefore, early diagnosis of cancer-related lymphedema is important. Lymphoscintigraphy is currently the most common method used for imaging diagnosis of lymphedema, but indocyanine green fluorescence lymphangiography (ICG lymphography) is also increasingly used for this purpose. The goal of this study was to compare the accuracy of these methods for diagnosis of lymphedema. Methods: This was a prospective comparative study, conducted at a general hospital in Japan. The subjects were 29 consecutive patients (all female; age range, 32-79 years) with lymphedema (58 limbs, including healthy ones) after gynecologic cancer care who underwent lymphedema treatment at The University of Tokyo and Saiseikai Kawaguchi General Hospital between April 2011 and December 2011. All subjects were referred to our department for lower extremity lymphoscintigraphy and ICG lymphography. The sensitivity and specificity of lymphoscintigraphy and ICG lymphography were calculated for all limbs and for diagnosis of early lymphedema in affected limbs (International Society of Lymphology stages 0 and I). In each analysis, receiver-operating characteristic curves were prepared to compare the accuracy of the two methods. Results: In receiver-operating characteristic analysis of 58 limbs, the area under the curve was 0.72642 for lymphoscintigraphy and 0.90943 for ICG lymphography. In 34 limbs with early lymphedema, the area under the curve was 0.55882 for lymphoscintigraphy and 0.81471 for ICG lymphography. Conclusions: ICG lymphography was more accurate than lymphoscintigraphy for detecting lymphedema and was particularly useful for diagnosis of early lymphedema. This is clinically important since early diagnosis may permit curative treatment of lymphedema.