Abstract

PET provides diagnostic information currently not available with traditional imaging. Retrospective analysis was performed of 104 patients with primary or recurrent melanoma who underwent PET for staging to determine sensitivity/specificity compared to body CT. 157 PET and 70 CT scans were analyzed with a mean follow up of 26 months. Metastatic events were confirmed with positive histology (73%) or documented disease progression.PET demonstrated 86% sensitivity and 97% specificity in 41 patients with metastasis. CT showed 57% sensitivity and 70% specificity in 30 patients with metastasis. Exclusion of areas not evaluated on CT (head, neck/supraclavicular, and extremities) increased CT sensitivity to 68%. Fifty-three patients underwent 67 consecutive CT and PET scans that detected 132 metastases in 30 individuals. PET detected a greater percentage of metastases (83%) compared to CT (56%), and specifically, in the soft tissue, neck, peripheral/mediastinal/intraabdominal lymph nodes, and small bowel. PET detected 100% of mediastinal metastasis while CT detected only 67%. Surprisingly, PET detected 84% of lung parenchymal metastasis compared to 72% with CT.PET is more sensitive and specific than CT for detection of melanoma metastasis and should be considered the primary staging study upon suspicion of recurrent disease. PET shows greater ability to detect soft tissue, small bowel, and lymph node metastasis that do not meet criteria designated as abnormal by CT. Likewise, CT does not routinely evaluate the supraclavicular area, neck, or upper/lower extremities. However, even when these sites are excluded from comparative analysis, PET is superior to CT in detecting melanoma metastasis.

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