Experimentelle Erprobung eines neuen Spulendesigns zur endoluminalen MRT am Beispiel des Schweinemagens

Newly developed surface coil for endoluminal MRI, depiction of pig gastric wall layers and vascular architecture in ex vivo study

BACKGROUND

The purpose of this study was to visualize the gastric wall layers and to depict the vascular architecture in vitro by using resected porcine stomachs studied with high-spatial resolution magnetic resonance (MR) imaging.

METHODS

Normal dissected porcine stomach samples (n = 4) were examined with a 3 Tesla MR system using a newly developed surface coil. MR images were obtained by the surface coil as receiver and a head coil as transmitter. High-spatial-resolution spin-echo MR images were obtained with a field of view of 8 x 8 cm, a matrix of 256 x 128 and slice thicknesses of 3 and 5 mm.

RESULTS

T1 and T2-weighted MR images clearly depicted the normal porcine gastric walls as consisting of four distinct layers. In addition, vascular architectures in proper muscle layers were also visualized, which were confirmed by histological examinations to correspond to blood vessels.

CONCLUSIONS

High-spatial-resolution MR imaging using a surface coil placed closely to the gastric wall enabled the differentiation of porcine gastric wall layers and the depiction of the blood vessels in proper muscle layer in this experimental study.

CT and endoscopic ultrasound in comparison to endoluminal MRI: preliminary results in staging gastric carcinoma

PURPOSE

To prospectively compare diagnostic parameters of a newly developed endoluminal MRI (endo-MRI) concept with endoscopic ultrasound (EUS) and hydro-computer tomography (Hydro-CT) in T-staging of gastric carcinoma on one patient collective.

MATERIAL AND METHODS

28 consecutive patients (11 females, 17 males, age range 46-87 years, median 67 years) referred for surgery due to a gastric malignancy were included. Preoperative staging by EUS was performed in 14 cases and by Hydro-CT in 14 cases within a time frame of 2 weeks. Ex vivo endo-MRI examination of gastric specimens was performed directly after gastrectomy within a time interval of 2-3h. EUS data were acquired from the clinical setting whereas Hydro-CT and endo-MRI data were evaluated in blinded fashion by two experienced radiologists and one surgeon well experienced in EUS on gastric carcinomas.

RESULTS

Histopathology resulted in 4 pT1, 17 pT2, 3 pT3 and 2 pT4 carcinomas with 2 gastric lymphomas which were excluded. Overall accuracy for endo-MRI was 75% for T-Staging of the 26 carcinomas. EUS achieved 42.9% accuracy; endo-MRI in this subgroup was accurate in 71.4%. Hydro-CT was correct in 28.6%, accuracy for endo-MRI in this subgroup was 71.4%.

CONCLUSION

The direct comparison of all three modalities on one patient collective shows that endo-MRI is able to achieve adequate staging results in comparison with clinically accepted methods like EUS and Hydro-CT in classifying the extent of tumor invasion into the gastric wall. However the comparison is limited as we compared in vivo routine clinical data with experimental ex vivo data. Future investigations need to show if the potential of endo-MRI can be transferred into a clinical in vivo setting.

Radiologische Bildgebung des oberen Gastrointestinaltraktes

CT, and multi-detector row computed tomography in particular, play a very important role in staging malignant tumors of the stomach. The optimized technique of so called "Hydro-CT", including distension to the gastric wall with 1-1.5 l oral contrast media, mainly water, has fostered the diagnostic value of CT in the diagnosis of diseases of the stomach. By using the "Hydro-CT" technique, the detection rate for gastric carcinoma is now between 89% and 94%, and for liver metastasis between 85% and 92%. For overall T staging, the sensitivity is rather low at between 43% and 65%, and for the lymph nodes between 64 and 88%. Depending on tumor type, multislice computed tomography (MSCT) supplies morphological details for defining the type of lesion (polyps, gastritis, lymphoma, gastrointestinal stromal tumours, carcinoma). Nevertheless, a definite differential diagnosis remains difficult. In addition, multiplanar reconstruction (MPR), derived from multi-detector row computed tomography data sets, is very helpful in localizing these pathologies and demonstrating their anatomic relationship to adjacent organs and vascular structures. MRI plays no major part in the diagnostic evaluation of the upper GI-tract.

New coil concept for endoluminal MR imaging: initial results in staging of gastric carcinoma in correlation with histopathology

Our aim was to conduct a prospective study to evaluate staging accuracy of a new coil concept for endoluminal magnetic resonance imaging (MRI) on ex vivo gastric carcinomas. Twenty-eight consecutive patients referred to surgery with a clinically proven primary gastric malignancy were included. Surgical specimens were examined with a foldable and self-expanding loop coil (8-cm diameter) at 1.5 Tesla immediately after total gastrectomy. T1- and T2-weighted and opposed-phase sequences (axial, frontal sections; 3- to 4-mm slice thickness) were acquired. Investigators blinded to any patient information analyzed signal intensity of normal gastric wall, gastric tumor, and lymph nodes. Findings were compared with histopathological staging. On surgical specimens, 2-5 gastric wall layers could be visualized. All gastric tumors (26 carcinomas, two lymphomas) were identified on endoluminal MR data (100%). Overall accuracy for T staging was 75% (18/24); sensitivity to detect serosal involvement was 80% and specificity 89%. N staging correlated in 58% (14/24) with histopathology (N+ versus N-). The endoluminal coil concept is feasible and applicable for an ex vivo setting. Endoluminal MR data provided sufficient detail for gastric wall layer differentiation, and therefore, identification of T stages in gastric carcinoma is possible. Further investigations in in vivo settings should explore the potential of our coil concept for endoluminal MR imaging.