Noninvasive evaluation of the lymphatic system with lymphoscintigraphy: A prospective, semiquantitative analysis in 386 extremities

Purpose: Lymphoscintigraphy has emerged as the diagnostic test of choice in patients with suspected lymphedema. To assess the lymphatic circulation of 386 extremities in 188 patients, we prospectively recorded a semiquantitative index of lymphatic transport in addition to visual evaluation of lymphoscintigraphy image patterns. Methods: Sixty-one male and 127 female patients were studied (mean age 48 years, range 13 to 87 years). Twenty had upper extremity swelling, and 168 had lower extremity swelling. The disease was bilateral in 60 patients. Lymphoscintigraphy was performed by injecting a mean of 503 μCi of technetium 99m-antimony trisulfide colloid subcutaneously into the second interdigital space of the extremity. Time for transport to regional lymph nodes, appearance of lymph vessels and nodes and distribution pattern were scored. These scores were compiled into a modified Kleinhans transport index (TI). To assess the venous circulation, 155 patients underwent evaluation of the venous system by impedance plethysmography, ultrasonography, or contrast venography. Results: The mean TI (± SEM) in 79 asymptomatic extremities was 2.6 ± 0.5, with 66 (83.5%) demonstrating normal lymphoscintigraphy pattern (TI < 5). Patients with clinical diagnosis of lymphedema (n = 124) had a mean TI of 23.8 ± 1.5; 81.5% of these were greater than 5. Fifty-six patients (30%) had primary and 68 (36%) had secondary lymphedema. (TI of 26 ± 3.5 and 22.1 ± 1.9, respectively, p = NS). Patients without any lymphatic transport (TI of 45) were more likely to have cellulitis in their history (p < 0.05). Contrast lymphangiography in six patients correlated with lymphoscintigraphy. Sixty-four patients (34%) had swelling without lymphedema (venous edema, cardiac edema, lipedema, etc.; TI of 1.9 ± 0.4, p < 0.001). Of the 41 patients with abnormal venous studies, 18 (44%) had an elevated TI. Conclusions: Semiquantitative evaluation of the lymphatic transport with lymphoscintigraphy reliably depicts abnormalities in the lymphatic circulation. Lymphoscintigraphy excluded lymphedema as a cause of leg swelling in one third of our patients.