Positron emission tomography scanning in malignant melanoma

Area of Science:

• Oncology
• Nuclear Medicine
• Medical Imaging

Background:

• Anatomically based computed tomography (CT) scans have shown limited utility in evaluating Stage III malignant melanoma.
• Functional imaging is needed to improve diagnostic accuracy for advanced melanoma staging.

Purpose of the Study:

• To investigate the efficacy and clinical utility of positron emission tomography (PET) scans in patients with Stage III malignant melanoma.
• To compare PET scan performance against traditional imaging methods for melanoma staging.

Main Methods:

• Prospective evaluation of 106 whole-body 2-fluorine-18, 2-fluoro-2-deoxy-D-glucose (FDG) PET scans in 95 patients with Stage III melanoma.
• Identification of abnormal areas on FDG PET scans based on increased metabolic activity.
• Pathological assessment of all identified abnormal foci to confirm malignancy.

Main Results:

• PET scanning identified 144 of 165 melanoma sites (87.3% sensitivity), missing microscopic disease and smaller lesions.
• A positive predictive value of 78.6% was observed, improving to 90.6% with clinical information.
• Specificity was 43.5% due to limited lymph node dissections; 19.7% of abnormal PET findings indicated unsuspected metastatic disease.
• Clinical management plans were altered in 15.1% of patients based on PET scan results.

Conclusions:

• FDG PET scanning is a valuable tool for managing Stage III melanoma patients considered for further surgery.
• Despite a significant false-positive rate, PET scans influenced patient management in a notable percentage of cases.
• PET's limitations in detecting microscopic disease restrict its utility for Stage I-II melanoma evaluation.