PET/CT Robustness In Melanoma

The incidence of melanoma is rising in the Netherlands and worldwide, with
current death rates of 800 patients per year in the Netherlands. Once
metastasized, death has historically been imminent for patients, until the
emergence of targeted- and immunotherapy. With response rates of 6-59% and
5-year survival rates reaching 40-50% from a prior 10%, a new era has begun
(1). However, as the variety in response rates signifies, a sizeable percentage
of patients do not respond and it is unclear if all lesions within a patient
respond similarly. Inter- and intra-tumour heterogeneity could be a
contributing factor to response failure (2,3). Characterising each tumour
lesion translates into biopsying each individual lesion leading to excessive
patient burden. PET/CT imaging provides the ability to visualize all lesions on
both an anatomical and functional basis. Adding PET/CT quantification analysis,
an unique and extensive non-invasive characterisation of all tumour lesions can
be provided. Until now only dermoscopy, confocal microscopy and CT based
quantification have been used in melanoma for diagnostic and prognostic model
building with promising results (4,5). One of the main challenges of imaging
based quantification research is the robustness of features, i.e. their
variability over time and susceptibility to different scan settings. No studies
have been performed to assess feature robustness in melanoma PET/CT
quantification, which is vital as a primary step to determine which features
are best to use in a predictive model for clinical application.

Determining the robustness of [18F]-FDG PET/CT based quantitative features in
metastatic melanoma patients by test-retesting [18F]-FDG PET/CT scans and
varying post processing scan settings, for future diagnostic and prognostic
clinical application.

This is a monocenter non-randomised prospective observational study, for a
duration of 1 year. The main procedure consists of repeating a [18F]-FDG PET/CT
scan *1 < 7 days of a first clinically indicated scan, all according to
standard clinical protocol. Addition of a variation in the post-processing
settings will be added after the patient has already left the scanner. 28
evaluable patients will be included of which a patient will be replaced if one
withdraws or is withdrawn from the study. A schedule for one patient is as
follows:

Day 1: [18F]-FDG PET/CT scan as planned (=test scan, clinically indicated)
Day 3, 4, 5, 6 or 7: [18F]-FDG PET/CT scan (=retest scan, additional scan for
study purposes)

Not applicable. There is minimal patient burden consisting of one extra
hospital visit of 1.5 hours for one additional [18F]-FDG PET scan with an
additional radiation dose of ±9 mSv.