Multimodal Imaging for Early Functional Response Assessment of super(90)Y-/ super(177)Lu-DO TATOC Peptide Receptor Targeted Radiotherapy with DW-MRI and super(68)Ga-DOTATOC-PET/CT

• Published in: Molecular imaging and biology Vol. 16; no. 4; pp. 586 - 594
• Main Authors: Wulfert, Sarah, Kratochwil, Clemens, Choyke, Peter L, Afshar-Oromieh, Ali, Mier, Walter, Kauczor, Hans-Ulrich, Schenk, Jens-Peter, Haberkorn, Uwe, Giesel, Frederik L
• Format: Journal Article
• Language: English
• Published: 01.08.2014
• ISSN: 1536-1632; 1860-2002
• DOI: 10.1007/s11307-014-0722-7

Purpose: The purpose of this study is to investigate the utility of contrast-enhanced magnetic resonance imaging (CE-MRI), diffusion-weighted MRI (DW-MRI), and super(68)Ga-DOTATOC positron emission tomography/computer tomography ( super(68)Ga-DOTATOC PET/CT) in the assessment of response to loco-regional peptide receptor radiotherapy (PRRT) with super(90)Y-/ super(177)Lu-DO TATOC in patients with hepatic metastases from gastro-entero-pancreatic neuroendocrine tumors (GEP-NET). Procedures: CE-MRI, DW-MRI, and super(68)Ga-DOTATOC-PET/CT images were acquired before and 3 months after one to two cycles of intra-arterial super(90)Y-/ super(177)Lu-DO TATOC therapy in 14 patients (nine female, five male; mean age, 54 plus or minus 9 years; range, 41-69 years) with hepatic metastases from GEP-NET. A total of 38 liver metastases were defined as target lesions for which the longest diameter, mean apparent diffusion coefficient (ADC sub(mean)) and maximum standardized uptake value (SUV sub(max)) were assessed. Based on changes in size on follow-up imaging, target lesions were classified as responding (RL) or nonresponding (NRL). Relative changes in tumor size, ADC sub(mean), and SUV sub(max) were compared between the two subgroups. Results: A total of 27 responding and 11 nonresponding lesions were successfully evaluated. Mean ADC sub(mean) increased significantly in RL (p=0.011) as well as NRL (p=0.025). A significant correlation was found between baseline ADC sub(mean) and both the percent ADC sub(mean) change (p=0.033) and decrease in lesion size after therapy (diameter p=0.006; volume p=0.002). SUV sub(max) of RL declined significantly by 24.1 % (p=0.014) and remained nearly unchanged in NRL. The change of SUV sub(max) correlated significantly with the pretreatment SUV sub(max) (p<0.001) and the change in lesion diameter (p=0.009). NRL with an ADC sub(mean) change >0.3110 super(-3) m m super(2)/s on first follow-up imaging showed a decrease in size in the long-term course. Conclusion: These results suggest that both DW-MRI and DOTATOC-PET imaging provide potential biomarkers for early assessment of treatment and stratification of therapy response, but that DW-MRI should be interpreted only in combination with SSTR expression and morphologic changes.