*3.1. Patient Characteristics*

This study focused on patients who had restaging PET/CT scans and met the inclusion criteria. Their demographic and clinicopathologic characteristics are shown in Table 1.


**Table 1.** Patient demographic and clinicopathologic characteristics.

A total of 167 patients presented for restaging; after excluding those that did not meet the inclusion criteria, 49 patients remained. This study consisted of 23 (46.9%) females and 26 (53.1%) males. Most of the patients (61.22%, n = 30) were less than 65 years old. The lower limb primary tumors were the most common, observed in 42.86% (n = 21) of the patients; the remainder were distributed in the upper limbs, head and neck, chest and

back. The histological types reported among these patients included unspecified malignant melanoma present in 71.43% (n = 35) patients and nodular type (18.37%, n = 9). The majority of the patients had stage IV disease (61.22%, n = 30).

The AJCC clinical stage at the time of referral was documented. Treatment received by the patients prior to the restaging PET was surgery (n = 36) and chemotherapy (n = 13). Patients were then restaged based on clinical and imaging findings. Patients in stages II and III were upstaged and those in stage IV either progressed or had stable disease. Based on the new stages, nine patients proceeded to receive immunotherapy, three received chemotherapy and the rest were followed up by observation and/or referral to palliative care.

The median follow-up time for survival was 12 months (interquartile range (IQR) of 3–32 months). High mortality rates were observed among males, those aged <65 years and those in clinical stage IV.

#### *3.2. Metabolic PET Parameters*

The median (IQR) SUVmax, MTV, TLG, whole-body MTV and whole-body TLG for the patients were 6.62 (3.1–12.6), 8.06 cm<sup>3</sup> (2.9–21.0), 19.49 (6.8–118.3), 33.36 (10.2–100.2) and 462.89 (59.3–1553.3), respectively. Compared to the survivors, non-survivors had a significantly higher median MTV (11.86 cm<sup>3</sup> vs. 5.68 cm3; *p*-value = 0.022), TLG (31.25 vs. 14; *p*-value = 0.0357), whole-body MTV (53.9 cm<sup>3</sup> vs. 14.4 cm3; *p*-value = 0.0076) and whole-body TLG (963.4 vs. 114.6; *p*-value = 0.0056) (Table 2).



IQR: Interquartile range; SUVmax: maxiumum standard uptake value; MTV: metabolic tumor volume; TLG: total lesion glycolysis.
