# Clinical value of combined 18F-FDG and 18F-P3BZA imaging in the diagnosis of melanoma

## TL;DR

Combining two imaging techniques improves melanoma diagnosis and treatment decisions.

## Contribution

Demonstrates that combining 18F-FDG and 18F-P3BZA PET/CT improves diagnostic accuracy and staging in melanoma.

## Key findings

- Combined imaging improved sensitivity for detecting metastases and lymph node involvement.
- Combined imaging changed treatment decisions in 26.3% of patients.
- Combined imaging improved TNM staging in 31.6% of patients.

## Abstract

This study aims to explore the clinical value of the combination of 18F fluorodeoxyglucose (18F-FDG) and N-[2-(dimethylamino) ethyl]-18F-5-fluoropicolinamide (18F-P3BZA) positron emission tomography/computed tomography (PET/CT) in melanoma patients.

A retrospective study was conducted on 19 melanoma patients who underwent 18F-FDG and 18F-P3BZA PET/CT scans at the Nuclear Medicine Department/PET Imaging Center of the Second Xiangya Hospital, Central South University, from March 2022 to March 2024. The diagnostic efficacy of 18F-FDG, 18F-P3BZA, and the combination of both for melanoma was compared, and the value of combined imaging for TNM staging and clinical treatment decision-making in melanoma patients was discussed.

The sensitivity of 18F-P3BZA in diagnosing primary lesions of melanoma, all metastases, sentinel lymph node metastases (SLNM), distant lymph node metastases (DLNM), and bone metastases (BM) was 100% (12/12), 71.4% (40/56), 72.4% (21/29), 66.7% (14/21), and 83.3% (5/6), respectively. The corresponding values for 18F-FDG were 91.7% (11/12), 91.1% (51/56), 86.2% (25/29), 95.2% (20/21), and 100% (6/6), respectively. Combined imaging showed a higher sensitivity in diagnosing SLNM, DLNM, and all metastases than 18F-P3BZA (χ2 = 7.105, p = 0.004; χ2 = 3.860，p = 0.045; χ2 = 15.604; p < 0.001). In addition, the specificity of 18F-FDG in diagnosing all metastases, SLNM, DLNM, and BM, was 50.0, 69.2, 56.3, and 100%, respectively, and the corresponding values for 18F-P3BZA were 81.8, 100, 75.0, and 100%, respectively. Combined imaging improved N and M staging in 31.6% (6/19) of melanoma patients and changed clinical treatment decisions in 26.3% (5/19) of melanoma patients.

The specificity of 18F-FDG alone in diagnosing melanoma is low, but it can be combined effectively with 18F-P3BZA. The combination of 18F-FDG and 18F-P3BZA PET/CT can further improve the detection efficiency of lesions, TNM staging, and clinical treatment decisions.