Experience with the Amplatz retrievable vena cava filter

The Amplatz retrievable inferior vena cava filter was designed to be used as either a permanent indwelling filter or a short-term, percutaneously removable filter. The authors placed 52 filters in 52 patients. No deaths occurred as a result of filter placement or usage. Follow-up in 42 (81%) patients included inferior vena cavography (n = 31), computed tomography (n = 4), duplex ultrasound (n = 4), and autopsy (n = 3). Inferior vena cava thrombosis was found in seven (17.5%) of the 40 previously nonobstructed venae cavae studied. Two patients with caval thrombosis required a second filter to prevent embolization of thrombus that had extended to the lung side of the first filter. No clinically evident pulmonary emboli after filter placement have been noted. Six filters were successfully retrieved or repositioned percutaneously. The relatively high rate of caval thrombosis with extension above the filter may be due to a higher trapping efficiency or to filter geometry. The role of this filter in the treatment of deep venous thrombosis and pulmonary emboli is unclear.     

Efficient conditional mutation of the vertebrate CENP-C gene

We have used gene targeting in the DT40 cell line to create a cell line which expresses a fusion between CENP-C and a mouse steroid receptor and which behaves as a conditional loss of function mutant of CENP-C. Under restrictive conditions these cells arrest at the metaphase/anaphase junction and after a delay of approximately 2.5 h die by apoptosis. These results indicate that CENP-C is either necessary for anaphase chromosome movement or for mediating a signal which triggers centromere function during anaphase. Our approach is simple and applicable to a wide range of proteins with general cell autonomous functions in vertebrates.      

Intracranial circulation: preliminary clinical results with three- dimensional (volume) MR angiography

The authors assessed the clinical utility of a magnetic resonance angiography technique in the evaluation of intracranial circulation. Eighteen patients with a low likelihood of cerebrovascular disease (control group) and 40 patients with suspected cerebrovascular disease were imaged with a FISP (fast imaging with steady precession) sequence (repetition time of 50 msec, echo time of 15 msec, velocity compensation in the read and section-select directions with acceleration compensation in the read direction, 15 degrees anisotropic volume, and a 1.25-mm partition thickness). Ninety-four percent of images in the control group and 72% of images in the group with cerebrovascular disease were considered useful for diagnosis. This technique can provide accurate images of intracranial circulation and can be performed in conjunction with two-dimensional spin-echo or gradient-echo imaging. It was most useful in the evaluation of patent intracranial aneurysms, vessel displacement, and large-vessel occlusive disease. Disadvantages included limited field of view, persistent signal voids, limited spatial resolution, and inadequate depiction of lesions with slow flow.     

Retrograde left atrial catheterization

Catheterization of the left atrium can provide valuable information about both congenital and acquired heart disease. The traditional approach to examination of the left atrium has been the transseptal route, which has occasionally been associated with serious complications. A method of retrograde left atrial catheterization has been developed that is performed with a modified standard catheter. The technique was tested in five dogs and was easy and safe to perform.     

Absorbed dose to the fetus during bone scintigraphy

The authors observed the uptake of radiopharmaceutical and calculated absorbed dose in fetuses of two patients who underwent bone scintigraphy with technetium-99m methylene diphosphonate. Dose estimates per administered activity were 17 mrad/mCi (4.6 microGy/MBq) for an 8-week-old fetus and 9.7 mrad/mCi (2.6 microGy/MBq) for an 18-week-old fetus. Neither fetus demonstrated radionuclide uptake above maternal background levels. The uterine activity showed rapid clearance, with an effective half-life of 12 minutes after reaching a maximum within 1 minute after injection. Major contribution to fetal dose comes from the presence of the radionuclide in the maternal bladder. The authors conclude that bone scintigraphy performed unknowingly in pregnant individuals presents negligible increased risk to the fetus.     

US-guided percutaneous pancreatography: experience in 75 patients

Seventy-five patients underwent ultrasound (US)-guided percutaneous pancreatography during a 3 1/2-year period. Pancreatography was successful in 67 patients, and there were no significant complications. The technique, which is easy to perform, was primarily employed to assist localization of pancreatic masses at fine-needle aspiration biopsy. It was also used to demonstrate pancreatic duct morphology when endoscopic retrograde pancreatography had failed or proved non-diagnostic. This enabled mapping of the duct system prior to pancreatic surgery. In cases of diagnostic difficulty, assessment of duct appearance with US-guided pancreatography was more accurate in differentiating carcinoma from chronic pancreatitis than was assessment with endoscopic retrograde pancreatography.