European Nuclear Medicine Guide
Semiquantitative Lymphoscintigraphy is a well-established functional examination to evaluate and confirm the diagnosis of lymphedema, as well as to measure lymphatic function.99mTc-nanocolloid (37-50 MBq) is injected intradermally in the interdigital space of Digit I-II of the foot.
Afterwards the patient undergoes 15 minutes of a treadmill exercise at 3,6 km/h to stimulate the lymphatic transport. Subsequently static images of the lower extremities and inguinal area are performed. The uptake in the inguinal region must be attenuation corrected, which is done by gamma camera based methods using a 57Co-flood source (Fig. 1) or by BMI corrected methods [174–176]. Attenuation correction is necessary in order to account for the inhomogeneous distribution of patient weight. The 57Co method uses a combination of planar transmission (without and with the patient in the scanner) to calculate photon absorption and emission measurements [174], whereas the BMI method uses a purely mathematical algorithm to correct pixel-by-pixel [175]. Additionally, visual assessment is necessary for the evaluation of abnormal lymphatic flow. By applying 57Co method the normal uptake is about > 14% and with BMI-method above 9% (Fig. 2) [177].
For the upper extremities similar approaches could be performed, however the interpretation is only done by visual analysis, since there are not so far well-established semiquantitative methods.
Fig. 1. Attenuation correction by transmission (57Co) and emission acquisitions
