Can integrated 18F-FDG PET/MR replace sentinel lymph node resection in malignant melanoma?

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Sentinel lymph node biopsy (SLNB) is crucial for accurate melanoma staging.
• Accurate detection of sentinel lymph node (SLN) metastases is vital for patient management.
• Advanced imaging techniques are being explored to improve SLN metastasis detection.

Purpose of the Study:

• To compare the diagnostic performance of 18F-FDG PET/CT, 18F-FDG PET/MR, and 18F-FDG PET/MR with DWI for detecting SLN metastases in melanoma.
• To evaluate the effectiveness of these imaging modalities in differentiating N-positive from N-negative melanoma patients.

Main Methods:

• A retrospective study included 52 melanoma patients who underwent 18F-FDG PET/CT and PET/MR with DWI.
• Lymphoscintigraphy and SPECT/CT were used to guide SLNB.
• Histopathology of SLNB served as the reference standard for evaluating imaging findings.

Main Results:

• PET/CT showed a sensitivity of 17.7% and specificity of 95.6%.
• PET/MR demonstrated a sensitivity of 23.5% and specificity of 96.9%.
• The addition of DWI to PET/MR did not improve the detection of metastases and increased false positives.

Conclusions:

• Integrated 18F-FDG PET/MR and PET/CT are not reliable for detecting SLN metastases in melanoma.
• Diffusion-weighted imaging does not enhance the diagnostic accuracy of PET/MR for this indication.
• SLNB remains indispensable for accurate melanoma staging, and these imaging modalities cannot replace it.