Two-dimensional perfusion angiography is a new method to quantify and evaluate tissue perfusion during endovascular intervention. The aim was to evaluate time-patterns and dynamics of contrast arrival and distribution before and after endovascular intervention in patients with critical limb threatening ischemia. Methods: Data were collected from 37 patients with critical limb threatening ischemia due to infra-inguinal occlusive disease having a successful endovascular procedure. two-dimensional perfusion angiography was used as a postprocessing software with analysis of numeric parameters related to arrival and distribution patterns of contrast. Results: Thirty-three patients were successfully analysed whereas four patients were excluded due to motion artefacts. All patients were successfully treated with recanalization of the superficial femoral, popliteal, below the knee-vessels or a combination. Short-term improvement at 30-day follow-up was noted both clinically and by ankle-brachial index and toe pressure measurements. A significant reduction in contrast arrival time between pre-and post-angioplasty runs was noted as measured by arrival time median 3.2 and interquartile range (2.5-4.2) vs. 2.6 (1.6-3.4) and time-to-peak 4.1 (3.6-5.0) vs. 3.1 (2.3-3.9) p ¼ 0.009. An increased wash-in rate was also observed 18.3 (12.6-21) vs. 30.1 (22-30.5) p ¼ 0.001 between pre-and post-angioplasty runs. Conclusions: The use of perfusion angiography for evaluation of foot-circulation during endovascular interventions provides new information regarding quantitative assessment of contrast inflow before and after endovascular intervention without the need for extra contrast or runs. No selective catheterisation is necessary. The technique is easily adopted in a clinical setting. Further studies are necessary to create robust clinical endpoints.

Purpose The aim of this prospective study was to validate the diagnostic performance of computed tomography angiography (CTA) in endoprosthesis stenosis in the superior mesenteric artery (SMA) using mean arterial pressure (MAP) gradients during angiography as a reference method. Methods Twenty-nine patients with mesenteric atherosclerotic disease underwent 45 paired measurements of endoprosthesis stenosis in the SMA with CTA and MAP gradients between March 2009 and July 2015. The grade of endoprosthesis stenosis in the SMA at CTA using the TeraRecon Aquarius workstation was correlated with MAP gradients. Results Grade of endoprosthesis stenosis in the SMA (r = 0.37, p = 0.013) correlated with MAP gradients. The intraclass correlations between the first and second CTA rater was 0.76 (95% CI 0.56–0.87) for estimation of grade of endoprosthesis stenosis in the SMA. The area under the receiver operating characteristics curve was 0.79 for diagnosis of significant endoprosthesis stenosis in the SMA at CTA for different threshold values using MAP gradient of ≥ 10 mmHg as reference. Sensitivity, specificity and positive predictive value for endoprosthesis stenosis in the SMA ≥ 50% at CTA were 52.4% (95% CI 31.0–73.7), 87.5% (95% CI 74.3–100.0) and 78.6 (95% CI 57.1–1.00), respectively. Conclusion Grading endoprosthesis stenosis in the SMA with CTA performed fair when using trans-stenotic MAP gradient as reference. Software development towards reduction of endoprosthesis artefacts may result in more accurate CTA assessment of the narrowest part.

Current power generation and oil & gas markets are dynamic with continuously growing requirements on gas turbines for high reliability and availability and low emissions and life cycle cost. In order to meet these growing requirements on the gas turbines, the OEM should sustain continued product improvement and employment of innovative solutions and technologies in the area of design, operation and maintenance. This paper describes the successful development and operation experiences of SGT-600 Siemens’ medium size gas turbine and in particular the latest achievements in maintenance and life cycle improvements. High reliability and availability of SGT-600 gas turbine were enabled by further improvements and modifications of the combustor, compressor turbine blade 1 and vane 1, power turbine diffuser and control system. The developed modifications enable operators to utilize the opportunity: • to extend the life cycle of the engine beyond 120,000 EOH (Equivalent Operating Hours), up to 180,000 EOH, depending on the previous operation profile and history of the installation; • to extend the maintenance intervals from 20,000 EOH to 30,000 EOH and that to increase the availability of the engine by up to 1%; • to reduce the emission level to the latest SGT-600 standards.