Imaging strategies in the management of gastric cancer: current role and future potential of MRI

Abstract

Accurate preoperative staging of gastric cancer and the assessment of tumor response to neoadjuvant treatment is of importance for treatment and prognosis. Current imaging techniques, mainly endoscopic ultrasonography (EUS), computed tomography (CT) and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET), have their limitations. Historically, the role of magnetic resonance imaging (MRI) in gastric cancer has been limited, but with the continuous technical improvements, MRI has become a more potent imaging technique for gastrointestinal malignancies. The accuracy of MRI for T- and N-staging of gastric cancer is similar to EUS and CT, making MRI a suitable alternative to other imaging strategies. There is limited evidence on the performance of MRI for M-staging of gastric cancer specifically, but MRI is widely used for diagnosing liver metastases and shows potential for diagnosing peritoneal seeding. Recent pilot studies showed that treatment response assessment as well as detection of lymph node metastases and systemic disease might benefit from functional MRI (e.g. diffusion weighted imaging and dynamic contrast enhancement). Regarding treatment guidance, additional value of MRI might be expected from its role in better defining clinical target volumes and setup verification with MR-guided radiation treatment.

Figure 1.

Axial T ₂ weighted magnetic resonance images (A) and corresponding high signal on diffusion-weighted images (b = 800 s/mm²) (B) of the primary gastric tumor and pathologic lymph node (red marking), as well as a coronal T ₂ weighted magnetic resonance image in one patient with cT3N1 gastric adenocarcinoma (C).

Figure 2.

Preoperative dynamic contrast enhanced (DCE) magnetic resonance images in axial plane approximately 1.25 min after intravenous contrast injection of two patients with gastric cancer (A and B). Figure B shows increased motion-related artifacts compared to Figure A.

Figure 3.

Preoperative T ₂-weighted magnetic resonance images in axial planes with pathologic lymph nodes (red markings) in one patient with gastric cancer.

Figure 4.

Preoperative T ₂-weighted magnetic resonance images (A) and planning CT images (B) of one patient with gastric cancer in axial planes. The red contouring reflects the clinical target volume (CTV) that could be used for preoperative radiation therapy.