Investigating the Role of Integrated 18FDG-PET/MRI in Predicting the Treatment Outcome of Neoadjuvant Concurrent Chemoradiotherapy Followed by Esophagectomy for Patients With Esophageal Cancer

Background:

Esophageal carcinoma is ranked as the 6th leading cancer in Taiwan. In recent years, the survival of patients with esophageal cancer has been improved by the use of neoadjuvant chemoradiotherapy with esophagectomy. But it is reported that only patients who were responsive to neoadjuvant therapy would have prolonged survival. And accurate clinical or imaging modality parameters for prognostic prediction are still lacking.

Traditionally, clinicians rely on endoscopic ultrasound (EUS) and computed tomography (CT) to evaluate the treatment response of esophageal cancer patients. After the neoadjuvant chemotherapy, the accuracy of EUS for assessment of primary tumor or regional nodal sites is reported to be 45-82% or 55-94%, respectively. As for CT, the reported sensitivity is also suboptimal, ranging from 33 to 55%. The specificity is 50-71%. In this regard, 18F-FDG PET/CT has higher sensitivity and specificity of 57-86% and 46-93% than other imaging modalities. But it is still difficult to precisely assess the treatment response depending on these imaging studies.

Functional MRI has been proven to be useful to evaluate treatment responses in various cancers. However, the application of functional MRI in esophageal cancer is limited. One investigator has reported that the apparent diffusion coefficient (ADC) value derived from diffusion MRI (DWI) had the potential to predict the response of esophageal cancer patients. After chemotherapy, the velocity of contrast across the vascular wall was also reported to change substantially in the dynamic contrast MRI (DCE MRI) study.

Integrated PET/MRI has the advantage to perform multiparametric imaging and to assess tumor metabolism (SUV, TLG), ADC, and DCE MRI parameters simultaneously. Recently, PET/MRI has been investigated in several cancers with promising results. In this study, the investigators prospectively explore the role of multiparametric PET/MRI imaging in evaluating the outcome of patients with esophageal cancer.