Fig. 2

Measurement of lymphatic obstruction using NIRF-ICGL and CSF level increase using MRI. (a) Lymphatic drainage in the cervical region of control and CLND group animals (at 2 and 8 weeks) using NIRF-ICGL. In the control group, the lymphatic flows along the collective lymphatic vessels toward the CLNs (yellow arrows). In the CLND group, the CLNs are not found, and abnormal lymphatic drainage patterns are observed in the neck and face at 2 and 8 weeks after surgery owing to lymphatic obstruction. (b) Quantitative results of lymphatic drainage spread. The threshold area is significantly different between the groups (t-test, *p < 0.05). (c) The time-domain waveforms of lymphatic contractions measured in the regions of interest (ROI, red dotted circle) of each group. Compared with the control group, the waveform and frequency of lymphatic contractions are alternated in the CLND group. (d) Signal conversion from the time-domain to the frequency-domain spectrum via fast Fourier transform (FFT) signal processing. In the control group, signal peaks are observed between 0.1 and 0.2 Hz, indicating frequent movements with a consistent period. (e) The images of # 13 and 17 slides among 27 MRI sections are used to measure the volume of the lateral ventricle in the control and CLND groups. The area within the red line represents the lateral ventricle. (f) The volume of the lateral ventricle (LV) determined by MRI in the control and CLND groups at 2 weeks and 8 weeks after model formation. The volume of the LV in the CLND group increased by approximately 15% compared with that of the control group (at 2 and 8 weeks), indicating an increase in CSF levels (t-test, **p < 0.01)