The prognostic value of positron emission tomography/magnetic resonance imaging in predicting survival in patients with adenocarcinoma of the esophagogastric junction.

Introduction: In recent years, the utility of positron emission tomography/magnetic resonance imaging (PET/MRI) has become increasingly significant in diagnostic settings. This study provides a five-year follow-up on a previous pilot study that demonstrated the feasibility of PET/MRI in predicting the resectability of adenocarcinoma of the esophagogastric junction (AEG). We aimed to evaluate whether this imaging modality could further serve as a prognostic tool for survival in AEG patients.

Methods: A total of 22 patients were included in the initial pilot study, with 17 of them undergoing surgery. All patients underwent three series of neo-adjuvant chemotherapy (NT). This follow-up study retrospectively analyzed the correlation between the apparent diffusion coefficient (ADC) and standard uptake value (SUV) measurements of the primary tumor from the original study with overall survival and recurrence. ADC and SUV values were measured prior to initiation of NT, and again 17-21 days into the first cycle of NT-administration, and the differences between the scans were calculated as ∆SUV_max, ∆ADC_b0, and ∆ADC_b50. Early treatment response was assessed using the Response Evaluation Criteria In Solid Tumors (RECIST). Binary logistic regression was employed to evaluate the predictive values of ADC and SUV parameters, and receiver operating characteristic (ROC) curves were generated to determine sensitivity, specificity, and area under the curve (AUC).

Results: As of January 7, 2022, 8 of the 22 patients were still alive. The AUC was calculated to assess the association of imaging parameters with long-term survival: ∆SUV_max: AUC = 0.74, sensitivity, 87.5%, specificity 62.5% (p = 0.037). ∆ADC_b0: AUC = 0.62, sensitivity 85.7%, specificity 57.1% (p = 0.400). ∆ADC_b50: AUC = 0.78, sensitivity 78.6%, specificity 85.7% (p = 0.011). Combining all three parameters yielded an AUC of 0.81, with a sensitivity of 78.6% and a specificity of 85.7% (p = 0.002). The results for individual measurements were: SUV_max(pre-NT): AUC = 0.56, sensitivity 78.6%, specificity 50% (p = 0.646). SUV_max(post-NT): AUC = 0.81, sensitivity 85.7%, specificity 87.5% (p = 0.002). ADC_b0(pre-NT): AUC = 0.55, sensitivity 71.4%, specificity 62.5% (p = 0.682). ADC_b0(post-NT): AUC = 0.63, sensitivity 78.6%, specificity 57.1% (p = 0.339). ADC_b50(pre-NT): AUC = 0.51, sensitivity 85.7%, specificity 37.5% (p = 0.952). ADC_b50(post-NT): AUC = 0.63, sensitivity 42.9%, specificity 100% (p = 0.279). No significant correlation was found between RECIST group and survival status (p = 0.15).

Conclusion: Our results indicate that PET/MRI is feasible for predicting long-term survival in AEG patients. The highest AUCs were achieved when combining SUV and ADC parameters, and when using post-NT SUV_max alone.