Simple and effective technique of guided biopsy in a closed MRI system.

BACKGROUND: Magnetic resonance (MR)-guided biopsies are generally regarded as complex interventions. We implemented interventional MR (IMR) with the resources available in and for practical application in a large (1100 beds) central hospital. METHODS: This simple and straightforward IMR technique uses a step-by-step approach for localization, access route planning, biopsy, verification in at least two planes, and postoperative control. The technique has been used and evaluated unchanged for more than 400 punctures and interventions. RESULTS: Contrast, signal, matrix options, and visibility of needle track and tip permit uncomplicated orientation. The mean duration of a biopsy is 19 min. The technique can be applied to all radiologic puncture settings without any technical or medical complications. CONCLUSION: The crucial step in implementing IMR is not to contemplate its application but to simply start applying the procedure.

Malignant biliary obstruction: treatment with self-expandable stainless steel endoprosthesis.

Metal endoprostheses of the Wallstent type were successfully inserted percutaneously and endoscopically in 80 consecutive patients with malignant obstructive biliary stenoses, who were followed for up to 18 months. The indication for treatment was jaundice due to malignant biliary obstruction. Repeat radiological investigations were performed if the patient had symptoms suggesting stent occlusion. After stent implantation, 88% of patients demonstrated a serum bilirubin decrease by more than 50%. We observed a 15% rate of serious complications, including a 10% rate of cholangitis with septicemia. There were no cases of stent migration or occlusion due to encrustation of bile. Recurrent jaundice occurred in 17.5% of patients due to progressive tumor growth after 3-10 months. In 5 of these patients, tumor overgrowth was redilated and/or restented. Of the 80 patients, 34% are alive after 2-12 months (mean: 242 days); of these, two-thirds are free of jaundice. Sixty-six percent of patients died between 3 days and 1.5 years (mean: 133 days). Although autopsy investigations revealed the possibility of tumor growth onto the inner surface of the stent, through the mesh of the endoprosthesis, no stent occlusion by tumor ingrowth into the lumen occurred. Self-expandable stainless steel endoprostheses provide good palliation in patients with malignant obstructive jaundice.

Use of the Wallstent in the venous system including hemodialysis-related stenoses.

Eighteen patients with a total of 23 venous stenoses or occlusions were treated with the Wallstent. In 5 patients treated for malignant stenosis there was one primary failure due to insufficient stent expansion. The other 4 patients showed rapid relief of their inflow obstruction, all remaining asymptomatic despite later stent occlusion in 1 patient. Four patients were treated for benign postoperative stenoses of the iliac or femoral vein. All stents remained patent for a period of 6 weeks-58 months. Nine patients were treated for one or multiple stenoses along the venous outflow tract of hemodialysis fistulas. Of 14 lesions that were eventually stented, 12 are still patent after 3-27 months (mean 19). However, 10 secondary interventions (eight percutaneous transluminal angioplasty (PTA), two stents) and three additional stent procedures for new lesions were necessary. Although our experience is limited, we believe that patients with tumor compression or postoperative strictures of large veins benefit from treatment with stents. Stenting of venous outflow stenoses in hemodialysis fistulas can significantly prolong stent function, however, PTA should always be the first treatment of choice.

Historical overview on the development and characteristics of stents and future outlooks.

The history and development of endovascular stents is described beginning with the Maass double helix spiral prosthesis, the first stent used in human clinical trials in the early 80s. This is followed by a description of the three main groups of stent techniques: the shape memory alloy stents, the balloon-expandable stents, and the self-expanding stainless steel stents. Requirements and new trends for improving clinical results in the future complete this text.

Biliary obstruction: treatment with self-expanding metal prostheses.

The authors percutaneously and endoscopically inserted 58 Wallstent endoprostheses in 42 consecutive patients with benign and malignant obstructive biliary stenoses. The three patients with benign obstructive jaundice were followed up for 48 months. Two of the stents occluded due to sludge formation, prompting percutaneous reentry. The 39 patients with malignant disease were followed up for 18 months. Twenty-six of these patients died 3 days to 1.5 years (mean, 133 days) after the procedure. Thirteen are alive after 2-12 months (mean, 242 days). Recurrent jaundice occurred in 11 patients (28%): in four patients due to tumor growth over the proximal end of the stent, in one patient due to excessive gallbladder hydrops, and in six patients due to liver failure. Although autopsy investigations revealed the possibility of tumor growth onto the inner surface of the stent through the stainless steel mesh of the endoprosthesis, stent occlusion by tumor ingrowth into the lumen was not encountered.