SPIO-enhanced MRI for sentinel lymph node mapping in oral cancer: a prospective feasibility study

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Early-stage oral cancer management involves invasive sentinel lymph node biopsy (SLNB) or neck dissection.
• A noninvasive imaging alternative for detecting lymph node involvement is highly desirable.
• Superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) offers potential for visualizing draining lymph nodes.

Purpose of the Study:

• To determine optimal SPIO injection and T2*-weighted MRI parameters for identifying oral cancer sentinel lymph nodes (SLNs).
• To map lymphatic drainage patterns using SPIO-enhanced MRI.
• To evaluate the capability of SPIO-enhanced MRI in detecting metastatic SLNs.

Main Methods:

• SPIO nanoparticles were injected submucosally around tongue tumors in ten patients post-SLNB.
• MRI was performed 1 hour after SPIO injection, with SPIO dose adjusted based on imaging quality.
• Lymphatic drainage patterns were compared between MRI and SPECT/CT; MRI findings were correlated with histopathology.

Main Results:

• A dose of 1 mg of iron was found to be suitable.
• All 25 SLNs identified on SPECT/CT were also visualized on MRI.
• MRI detected significantly more lymph nodes (107) compared to SPECT/CT (55), but could not differentiate metastatic from non-metastatic nodes based on imaging characteristics.

Conclusions:

• SPIO-enhanced T2*-weighted MRI is effective for mapping SLNs and lymphatic drainage patterns in oral cancer.
• This technique visualizes more lymph nodes than SPECT/CT, offering better anatomical detail.
• Distinguishing metastatic from non-metastatic lymph nodes solely based on SPIO-enhanced MRI is not currently feasible.