68Ga-DOTATATE PET/CT and MRI with Diffusion-Weighted Imaging (DWI) in Short- and Long-Term Assessment of Tumor Response of Neuroendocrine Liver Metastases (NELM) Following Transarterial Radioembolization (TARE)

Abstract

The aim of this study was to evaluate the role of SUV and ADC in assessing early response in patients with NELM following TARE. Thirty-two patients with pre- and postinterventional MRI with DWI and 68Ga-DOTATATE PET/CT were included. ADC and SUV of three target lesions and of tumor-free spleen and liver tissue were determined on baseline and first follow-up imaging, and tumor to spleen (T/S) and tumor to liver (T/L) ratios were calculated. Response was assessed by RECIST 1.1 and mRECIST on first follow-up, and long-term response was defined as hepatic progression-free survival (HPFS) over 6, 12, and <24 months. In responders, intralesional ADC values increased and SUV decreased significantly regardless of standard of reference for response assessment (mRECIST/RECIST/HPFS > 6/12/24 m). Using ROC analysis, ΔSUV T/S ratio (max/max) and ΔSUV T/L ratio (max/mean) were found to be the best and most robust metrics to correlate with longer HPFS and were superior to ΔADC. ΔT/S ratio (max/max) < 23% was identified as an optimal cut-off to discriminate patients with longer HPFS (30.2 m vs. 13.4 m; p = 0.0002). In conclusion, early percentage changes in SUV tumor-to-organ ratios on first follow-up seem to represent a prognostic marker for longer HPFS and may help in assessing therapeutic strategies.

Quantitative SSTR-PET/CT: a potential tool for predicting everolimus response in neuroendoctine tumour patients

“…32,33 Additionally, in a different study, the change of T/S and T/L ratios on the first follow-up was identified as the best metric to correlate with longer hepatic PFS in NET patients undergoing TARE. 34 The main limitation of this study was its small sample size, which is related to the low incidence of NETs and everolimus representing a second-line treatment. Additionally, the retrospective analysis represents a limiting factor, as time intervals between PET/CT scans and everolimus treatment were heterogeneous, and prior therapies differed among patients.…”

Neuroendokrine Tumoren – von der morphologischen zur funktionellen Bildgebung

“…Gastrointestinale NET erscheinen hypointens in T1, hyperintens in T2 und zeigen eine KM-Aufnahme sowie eine Diffusionsrestriktion in diffusionsgewichteten Sequenzen. Die DWI eignet sich zudem zur Beurteilung therapieassoziierter Veränderungen nach transarterieller Chemoembolisation (TACE) oder selektiver interner Radiotherapie (SIRT) [31,32]. Bezüglich der Primärtumorlokalisation weist die MRT eine ähnliche Sensitivität und Spezifität wie die CT-Bildgebung auf [33,34].…”

Neuroendokrine Tumoren – von der morphologischen zur funktionellen Bildgebung

“…Gastrointestinale NET erscheinen hypointens in T1, hyperintens in T2, zeigen eine KM-Aufnahme und eine Diffusionsrestriktion in diffusionsgewichteten Sequenzen. Die DWI eignet sich zudem zur Beurteilung therapieassoziierter Veränderungen nach transarterieller Chemoembolisation (TACE) oder selektiver interner Radiotherapie (SIRT) [31,32]. Bezüglich der Primärtumorlokalisation weist die MRT eine ähnliche Sensitivität und Spezifität wie die CT-Bildgebung auf [33,34].…”