[Lymph node image with ultrasmall superparamagnetic iron oxide and comparison with pathological result].

Area of Science:

• Biomedical Imaging
• Oncology
• Pathology

Background:

• Lymph node assessment is crucial for staging cancer and diagnosing inflammation.
• Ultrasmall superparamagnetic iron oxide (USPIO) is an MRI contrast agent that can accumulate in macrophages.
• Understanding USPIO enhancement patterns in different lymph node conditions is vital for accurate diagnosis.

Purpose of the Study:

• To characterize USPIO-enhanced MRI in rabbit models of lymphadenitis and lymph node metastasis.
• To correlate MRI findings with ultrastructural and histological features of lymph nodes.

Main Methods:

• 36 rabbits were modeled with either lymphadenitis or VX2 tumor cell-induced metastasis.
• MRI scans were performed before and after USPIO administration.
• Histopathology (HE, Prussian blue) and electron microscopy analyzed lymph node microstructure and USPIO distribution.

Main Results:

• USPIO-enhanced MRI revealed distinct T2 signal reduction patterns: central in inflammatory nodes, homogenous and faint in metastatic nodes.
• Enhancement rates differed significantly (57.39% inflammatory vs. 29.45% metastatic, P < 0.01).
• USPIO particles were primarily located in macrophages, with distribution varying between inflammatory and metastatic lymph nodes.

Conclusions:

• USPIO enhancement patterns are closely linked to the distribution and function of intra-node macrophages.
• These findings suggest that USPIO-enhanced MRI can help differentiate between inflammatory and metastatic lymph nodes.
• Macrophage status and USPIO uptake impact the accuracy of lymph node property diagnosis using USPIO-enhanced MRI.