Injection of a silicone prepolymer system into the gallbladder of rabbits.

The aim of this study was to assess the feasibility of a new nonsurgical treatment for cholelithiasis. This involved injecting a liquid prepolymer into the gallbladder which would polymerize in situ, entrapping existing gallstones and permanently filling the gallbladder so as to prevent subsequent gallstone formation. Initially, several silicone prepolymer mixtures were tested in vitro for viscosity, cure time, radiopacity, and consistency when polymerized. The optimal system with regard to these parameters consisted of two room temperature vulcanizing silicones (3110 and 200), a catalyst (F), and barium sulfate. This mixture was then injected into beakers containing human gallstones alone and in combination with bile, and was periodically evaluated over six months. It was also injected into the gallbladder of six rabbits and left for 12 weeks. No clinical complications were noted in any of the animals. The cured silicone system maintained its original shape and did not fragment. At necropsy, the casts were free in the rabbits' gallbladders, with small accumulations of biliary sludge adhered to their surfaces. No mucocele of the gallbladder was found in any of the rabbits. Cholecystic histology was normal in all cases, and only one animal exhibited a mild chronic portal triaditis. These promising results indicate the need for further studies of the technique and refinement of the silicone formulation.

Mediastinal metastases of infradiaphragmatic malignancies.

Mediastinal lymph node metastases from infradiaphragmatic malignancies are reported to be a rare occurrence. The results of previous studies have been based on the evaluation of chest radiographs. In this study we retrospectively reviewed the chest and abdominal computed tomography examinations of 50 such patients. Of these, 25 had renal cell carcinoma and the remainder, other genitourinary or gastrointestinal carcinomas. The major nodal groups involved in the mediastinum were the right paratracheal in 41 cases, subcarinal in 31, paraesophageal in 26, and aortopulmonary in 25. Hilar nodes were involved in 21 cases. In the abdomen, para-aortic and or retrocrural adenopathy was present in 29 cases. Of 21 patients with pulmonary metastases, only 12 cases were associated with ipsilateral hilar lymphadenopathy. Supraclavicular lymphadenopathy occurred in only 8 patients. These results suggest that spread of infradiaphragmatic malignancies to the mediastinum occurs primarily by extension from the retrocrural and para-aortic nodes into the thoracic duct and then by antegrade flow in the thoracic duct and its collaterals, with retrograde flow from these channels to the mediastinal nodes.

Automatic motion correction for breast MR imaging.

In 29 gadolinium-enhanced breast magnetic resonance (MR) examinations, breast motion prevented accurate and efficient image processing. To compensate for global rotations and translations, an automatic motion correction method with a ratio-variance minimization algorithm was used to align images at multiple time points through an iterative process. This method reduced breast motion and improved the accuracy and efficiency of lesion detection.

Stereoscopically guided characterization of three-dimensional dynamic MR images of the breast.

A workstation was used to postprocess volume-rendered three-dimensional (3D) dynamic contrast material-enhanced magnetic resonance (MR) images of a breast carcinoma and a breast adenoma. Use of a 3D cursor allowed stereoscopic interactive probing of specific voxels to quantify contrast enhancement over time, which was mapped to a gray scale that effectively displayed enhancement as a fourth dimension. This technique is generally applicable to any time-dependent 3D imaging modality.