False-negative results after stereotactically guided vacuum biopsy.

The purpose of this study was to determine the false negative rate of stereotactically guided vacuum biopsy (VB). Data of patients with benign lesions in VB were evaluated retrospectively during a median follow-up period of 21 months. A total of 404 VB were considered benign and representative and were recommended for follow-up. Of these 404 lesions, 195 were completely removed radiologically. Follow-up data were available for 354/404 patients (87.6%), with intervals ranging from 3 to 66 months (median 21, mean 22.4). Reintervention or surgery was necessary in 13/354 (3.7%) cases. Of these cases, 5/354 (1.4%) turned out to be false negatives. Four of these cases showed large areas of microcalcifications or several clusters, and only partial removal was possible due to the size of the lesions. Although VB is an accurate procedure for diagnosing nonpalpable breast lesions with a low cancer miss rate, we consider the exclusion of malignancy in cases of disseminated microcalcifications or several clusters as a limitation. The radiologic-pathologic correlation in these cases is a challenge, particularly in terms of the residuals. Strict follow-up of benign lesions is essential to avoid delayed cancer diagnosis.

Interobserver-variability of lung nodule volumetry considering different segmentation algorithms and observer training levels.

OBJECTIVE: The aim of this study was to investigate the interobserver variability of CT based diameter and volumetric measurements of artificial pulmonary nodules. A special interest was the consideration of different measurement methods, observer experience and training levels. MATERIALS AND METHODS: For this purpose 46 artificial small solid nodules were examined in a dedicated ex-vivo chest phantom with multislice-spiral CT (20 mAs, 120 kV, collimation 16 mm x 0.75 mm, table feed 15 mm, reconstructed slice thickness 1mm, reconstruction increment 0.7 mm, intermediate reconstruction kernel). Two observer groups of different radiologic experience (0 and more than 5 years of training, 3 observers each) analysed all lesions with digital callipers and 2 volumetry software packages (click-point depending and robust volumetry) in a semi-automatic and manually corrected mode. For data analysis the variation coefficient (VC) was calculated in per cent for each group and a Wilcoxon test was used for analytic statistics. RESULTS: Click-point robust volumetry showed with a VC of <0.01% in both groups the smallest interobserver variability. Between experienced and un-experienced observers interobserver variability was significantly different for diameter measurements (p=0.023) but not for semi-automatic and manual corrected volumetry. A significant training effect was revealed for diameter measurements (p=0.003) and semi-automatic measurements of click-point depending volumetry (p=0.007) in the un-experienced observer group. CONCLUSIONS: Compared to diameter measurements volumetry achieves a significantly smaller interobserver variance and advanced volumetry algorithms are independent of observer experience.

A new concept for covered stent protected carotid angioplasty: an ex vivo study.

OBJECTIVE: To determine the efficacy of a covered stent prototype designed for protected carotid angioplasty to reduce cerebral embolization. MATERIAL AND METHOD: The covered stent tested is made of nitinol, coated with a polyurethane membrane (MembraX trade mark; porous size 80 micro m). In a bench-top model (flow-rate 650 ml/min, pulsatile flow [dicrote] 123 Pulses/min, pressure 100/60 mm Hg [mean pressure 80 mmHg]) with inserted human carotid (n = 6) stent implantation was performed (8/32 mm). Passed particles (mg) were determined in the effluent of a 100 micro m filter prior to intervention, after stent deployment and after final dilation (5 mm). RESULTS: When stenting carotid arteries obtained from human cadavers, the highest rate of particle embolization was measured while crossing the lesion with the delivery device (6,8 mg; for all p < 0,05), embolization after additional balloon angioplasty and particle rates measured in the effluent filter prior covered stent placement were significantly lower (3,8 mg; p < 0,05). Branches of the external carotid artery remained patent in all cases. CONCLUSIONS: The introduced concept of covered stent protected carotid angioplasty with the MembraX trade mark prototype has proven promising results for low cerebral embolization rates ex vivo. Further evaluations using an animal model and a miniaturization of the delivery device are warranted prior to human use.