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- Lisi, Matteo, 1982-, et al.
(författare)
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Severity of aortic stenosis predicts early post-operative normalization of left atrial size and function detected by myocardial strain
- 2013
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 167:4, s. 1450-1455
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Aortic stenosis (AS) causes significant disturbances in left ventricular (LV) and left atrial (LA) function irrespective of the extent of myocardial hypertrophy which associates the increased afterload. We hypothesize that aortic valve replacement (AVR) and removal of LV outflow tract obstruction should result in LA size and function recovery, even partial, and were set to study this in a group of patients with AVR for AS.METHODS: Peak atrial longitudinal strain (PALS) was evaluated in 43 patients with severe isolated AS and normal EF (56.6±3.8%) and no obstructive coronary artery disease candidates for AVR, pre-operatively and then 40days and 3months after surgery. Results were compared with those from 34 age- and gender-matched healthy controls.RESULTS: LVEF remained unchanged and LV mass regressed after AVR. Global PALS was reduced pre-operatively and increased 40days after surgery (p=0.002) and showed only a slight further increase at 3months follow-up (p<0.0001). Indexed LA volume was increased before surgery, but significantly fell 40days after surgery (p<0.0001) and showed only a slight further reduction after 3months (p<0.0001). Trans-aortic mean gradient change after surgery was the only independent predictor of the recovery of LA size and function.CONCLUSIONS: AVR reverses LA abnormalities and regains normal atrial function, a behavior which is directly related to the severity of pre-operative LV outflow tract obstruction. Early identification of LA size enlargement and functional disturbances might contribute to better patient's recruitment for AVR.
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- Pani, R., et al.
(författare)
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A study of response of a LuYAP : Ce array with innovative assembling for PET
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 795, s. 82-87
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Tidskriftsartikel (refereegranskat)abstract
- We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2 mm×2 mm×10 mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015 mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2 mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated 99mTc radioisotope (140 keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4. Although the dielectric coating pixel insulator cannot overcome the inherent limitations of LuYAP crystal due to its self-absorption of light (still present), this study demonstrated that the new coating treatment allows better light collection (nearly close to the expected one) with in addition a very good uniformity between different pixels. These results confirm the high potentiality of this coating for any other crystal array suited for imaging application and new expectations for the use of LuYAP for PET systems.
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