Is 18F-FDG PET/CT Necessary During Vismodegib Therapy for Basal Cell Carcinoma? Quantitative Changes and Incremental Value Beyond CT
WORLD JOURNAL OF NUCLEAR MEDICINE, cilt.1, sa.2026, ss.1-9, 2026 (ESCI)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 1 Sayı: 2026
- Basım Tarihi: 2026
- Doi Numarası: 10.1055/s-0046-1829369
- Dergi Adı: WORLD JOURNAL OF NUCLEAR MEDICINE
- Derginin Tarandığı İndeksler: Emerging Sources Citation Index (ESCI)
- Sayfa Sayıları: ss.1-9
- Bursa Uludağ Üniversitesi Adresli: Evet
Özet
Objectives The role of 18F-fluorodeoxyglucose positron emission tomography/com-
puted tomography (18F-FDG PET/CT) in monitoring basal cell carcinoma (BCC) during
vismodegib therapy remains poorly defined, particularly in patients with extensive,
multifocal, or Gorlin syndrome–associated disease. This study aimed to evaluate
metabolic and anatomic treatment-response findings and the incremental diagnostic
value of 18F-FDG PET beyond CT in this setting.
Materials and Methods Patients with histopathologically confirmed BCC who under-
went 18F-FDG PET/CT during vismodegib therapy between December 2015 and
August 2026 were retrospectively reviewed. Metabolic response was classified using
PERCIST (Positron Emission Tomography Response Criteria in Solid Tumors)-like criteria
based on serial maximum standardized uptake value (SUVmax) measurements, and
tumor-to-liver ratio (TLR) was additionally calculated as a background-normalized
metabolic parameter. Patients without suitable paired imaging for metabolic response
assessment because of absent follow-up PET/CT, lack of an FDG-avid target lesion, or
intervening local treatment were considered not evaluable for categorical metabolic
response. Baseline and follow-up SUVmax and TLR values were compared using the
Wilcoxon signed-rank test. Continuous variables were summarized using descriptive
statistics, and categorical variables were reported as frequencies and percentages.
Results Sixteen patients were included, of whom 5 had Gorlin syndrome. Primary
lesions were predominantly craniofacial, occurring in 15 of 16 patients (93.8%), and 11
patients had orbital involvement. Baseline FDG avidity was present in 10 patients,
whereas 6 had low or absent uptake. Among 8 patients with paired quantitative PET/CT
measurements, the median baseline and follow-up SUVmax values were 5.45 and 4.50,
respectively, with no significant interval change (Wilcoxon signed-rank test, p ¼ 1.000).
Similarly, paired TLR values showed no significant interval change (p ¼ 0.834). Cate-
gorical PET response assessment was feasible in seven patients. Others were not
evaluable because of absent follow-up PET/CT, no FDG-avid target lesion, or interven-
ing local treatment. A CT-measurable target lesion was present in nine patients (56.2%),
while PET provided incremental information beyond the CT component in three
patients (18.8%), primarily through the identification of additional metabolically active
lesions or disease findings not apparent on CT.
Conclusion Although 18F-FDG PET/CT may provide additional metabolic information
in selected patients with advanced, multifocal, or Gorlin syndrome–associated BCC, its
incremental diagnostic contribution beyond CT during vismodegib therapy appears
limited. Selective use may therefore be more appropriate than routine serial imaging.