Usefulness of [68Ga]Ga-DOTA-FAPI-04 PET/CT in patients presenting with inconclusive [18F]FDG PET/CT findings

Clinical Results of Fibroblast Activation Protein (FAP) Specific PET and Implications for Radiotherapy Planning: Systematic Review

“…For the lower gastrointestinal tract, in general, the main benefit of FAP-specific PET was not limited to target volume delineation but a better assessment of tumor spread and, therefore, more information to decide the oncological management of a patient. However, even though nearly all head-to-head comparisons with FDG PET emphasize the increased sensitivity of FAP-specific PET, there is still not much information on its specificity, hinting at a decreased performance in patients who have other diseases that provoke or are defined by an inflammatory reaction such as chronic pancreatitis [25]. This also applies for the use of FAP-specific PET for bone metastases.…”

“…The authors also report that FAP-specific PET detected more brain metastases, although the number of cases was limited (6 patients with FAP-specific PET vs. 3 patients with FDG PET). Other studies report on the detection of brain metastases with FAP-specific PET as well and also noting that the lower absolute uptake but higher tumor-to-background ratio observed in glioma also applies there [25,38].…”

“…Other publications also reported on FAP-specific PET for head and neck tumors, among them the discovery of an occult nasopharyngeal carcinoma in a patient with cancer of an unknown primary (CUP) [25]. It is also mentioned that the low uptake of healthy brain tissue helps determine the tumor spread towards the skull base [36].…”

“…While several publications contain at least one patient with breast cancer, no dedicated analysis for target volume delineation has been performed [12,26,32,36,37]. The biggest collective consisted of four patients (3 invasive ductal carcinomas, 1 invasive lobular carcinoma) analyzed by Chen et al who found that FAP-specific PET was able to detect more lymph node metastases than FDG PET in this small sample [25].…”

“…In a publication by the same group on patients with inconclusive FDG PETs, FAP-specific PET detected an occult esophageal primary in a patient whose cancer was formerly classified as CUP. In two other cases, the tumor stage was changed by detecting additional lymphatic metastases in two patients with esophageal cancer [25].…”