Prospective comparison of MR with diffusion-weighted imaging, Endoscopic Ultrasound, MDCT and Positron Emission Tomography-CT in the preoperative staging of oesophageal cancer: results from a pilot study

OBJECTIVES: To compare the diagnostic performance of Magnetic Resonance (MR) and diffusion-weighted imaging (DWI), Multidetector Computed Tomography (MDCT), Endoscopic Ultrasonography (EUS) and 18F-FDG (Fluorodeoxyglucose) Positron Emission Tomography - Computed Tomography (PET-CT) in the preoperative loco-regional staging of oesophageal cancer. METHODS: Eighteen patients with oesophageal or Siewert I tumour (9 directly treated with surgery and 9 addressed to chemo/radiotherapy before) underwent 1.5 T MR and DWI, 64-channels MDCT, EUS and PET-CT before (n=18) and also after neoadjuvant treatment (n=9). All images were analysed and staged blindly by dedicated operators (7th TNM edition). Two radiologists calculated independently the Apparent Diffusion Coefficient (ADC) from the first scan. Results were compared with histopathological findings. After the population had been divided according to local invasion (T1-2 vs T3-4) and nodal involvement (N0 vs N+), sensitivity, specificity, accuracy, positive and negative predictive value were calculated and compared. Quantitative measurements from DWI and PET-CT were also analysed. RESULTS: For T staging, EUS showed the best sensitivity (100%) while MR showed the highest specificity (92%) and accuracy (83%). For N staging, MR and EUS showed the highest sensitivity (100%), but none of the techniques showed adequate results for specificity. Overall, MR showed the highest accuracy (66%) for N stage, even though this was not significantly different to the other modalities. ADC was different between surgery-only and chemo/radiotherapy groups (1.90 vs 1.30 x 10-3 mm2/s, respectively; p= 0.005) - optimal cut off for local invasion:1.33 x 10-3 mm2/s (p=0.05). Difference in SUV was also very close to conventional levels of statistical significance (8.81 vs 13.97 g/cc, respectively; p= 0.05) - optimal cut off: 7.97 g/cc (p=0.44). CONCLUSIONS: In this pilot study we have shown that MR with DWI could enrich the current preoperative workup for oesophageal cancer and could be used for T and N staging. However, larger studies will need to be carried out before introducing this technique in the standard diagnostic pathway, in order to understand if MR with DWI could change its management and replace more costly or invasive tests such as PET-CT or EUS. Advances in knowledge: This pilot study represents the first effort where the four techniques have been prospectively compared together for oesophageal cancer staging. The combination of MR and DWI could provide important, additional information for staging and initial treatment decision-making.