Endoscopic MRI: preliminary results of a new technique for visualization and staging of gastrointestinal tumors

The principle of endoscopic ultrasonography--introducing the transducer of an external imaging method, such as ultrasonography, in combination with an endoscope into the gastrointestinal tract for higher-resolution imaging--has also been applied to magnetic resonance imaging (MRI). We report here on our preliminary experience with a new method of endoscopic MRI in the upper gastrointestinal tract.

Endoscopic MRI was performed in 32 patients with esophageal (n = 8) or gastric diseases (n = 24), mostly tumors (n = 26). Most cancers were at an advanced stage (T3/T4). A prototype MRI endoscope connected to a 1.5 tesla MRI scanner was used. The accuracy of endoscopic MRI in visualizing and staging gastrointestinal lesions was assessed.

The normal gastrointestinal wall consisted of three layers, and tumors were visualized as having a low signal intensity on both T1- and T2-weighted sequences. Destruction of the wall layers was found to be characteristic of malignancy. Sufficient images were obtained in seven of eight esophageal cases (88%), but in only 14 of 24 gastric cases (58%). In patients in whom adequate visualization was achieved, the endoscopic MRI results of local and regional staging were consistent with surgical, histopathological, CT and/or EUS results in all six esophageal cancer cases and in 89% (T stage) and 56% (N stage) of the nine patients with gastric cancer.

These preliminary results of endoscopic MRI are the first to be reported in the English literature. They show the potential of the method for local and regional staging, three-dimensional visualization of lesions being a potential advantage. Further technical improvements are expected.