Intravascular ultrasound predictors of outcome after peripheral balloon angioplasty

Objective:This study investigates the potential role of intravascular ultrasound (IVUS) in the outcome in patients undergoing percutaneous transluminal angioplasty (PTA) of the superficial femoral artery.Materials:Angiographic and the qualitative and quantitative IVUS data obtained at the narrowest site derived from 39 patients before and after PTA were analysed.Results:Angiographically the diameter of the remaining stenosis seen after PTA was classified as < 50% in 31 patients (success); in eight patients a failure was encountered. Evaluating at 6 months the functional and anatomic results of the PTA in 31 patients, the intervention was a success in 14 patients (Group I) and a failure in 17 patients (Group II). The remaining eight patients defined as angiographic failure following PTA comprised Group III. Neither qualitative nor quantitative IVUS data obtained before PTA could predict outcome. Conversely, after PTA, the extent of dissection was significantly more severe in Groups II and III than in Group I. Similarly, significant differences were found between Groups I and II for mean free lumen area (13.2 vs. 9.7 mm2, respectively) and mean free lumen diameter (4.1 vs. 3.5 mm, respectively). Quantitative data obtained in Group II were similar to those in Group III.Conclusion:This preliminary study demonstrates that following PTA the extent of dissection, free lumen area and diameter seen with IVUS are predictive factors of patency. Future studies with more patients are mandatory to further highlight the sensitivity of these observations

Gas gain stability of MSGCs operating at high rate

Micro Strip Gas Counters (MSGCs) with coated and uncoated borosilicate glass substrates have been investigated on their high rate capability and long-term gas gain stability. It is shown that the gain remains almost constant at count rates up to 105 mm-2 s-1 when a semiconductive layer of S8900 glass or polydiamond is applied under or over the strips. The application of such a coating also favours the gain stability at long-term operation. However, the maximum attainable gas gain for coated substrates is 4-10 times smaller than for bare borosilicate glass supports. For the latter substrate type, we observe less ageing when the strips are made of nickel instead of aluminium or copper.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A curved Micro-Strip Gas Counter for synchrotron radiation time resolved SAXS/WAXS experiments

We are constructing a positive-sensitive detector that is capable of detecting an X-ray diffraction pattern with a count rate of up to 1 MHz per channel. The channel width is 0.4 mm. This detector is based on the Micro-Strip Gas Counter (MSGC) technology. The detecting and converting medium is argon or xenon gas. The wedge-shaped substrates carry charge-sensitive strips, which define detector channels in the counter gas pointing to the scattering centre, enabling parallax-free detection. A conversion range of 4 cm along the strips is available, so the efficiency is higher than for conventional designs, while the count rate per centimetre strip is lower. We present test results on the rate capability and the energy resolution for a prototype.SCOPUS: ar.jinfo:eu-repo/semantics/publishe