The technique combines deformation from high resolution, non-tagged MR image data CP-456773 with a detailed computational model, including estimated myocardial material properties, fiber direction, and active fiber contraction, to provide a comprehensive description of myocardial contractile
function. A normal volunteer (male, age 30) with no history of cardiac pathology was imaged with a 1.5 T Siemens Avanto clinical scanner using a TrueFISP imaging sequence and a 32-channel cardiac coil. Both tagged and non-tagged cine MR images were obtained. The Hyperelastic Warping solution was evolved using a series of non-tagged images in ten intermediate phases from end-diastole to end-systole. PRIMA-1MET Apoptosis inhibitor The solution may be considered as ten separate warping problems with multiple templates and targets. At each stage, an active contraction was initially applied to a finite element model, and then image-based warping penalty forces were utilized to generate the final registration. Warping results for circumferential strain (R(2) = 0.75) and radial strain (R(2) = 0.78) were strongly correlated with results
obtained from tagged MR images analyzed with a Harmonic Phase (HARP) algorithm. Results for fiber stretch, LV twist, and transmural strain distributions were in good agreement with experimental values in the literature. In conclusion, Hyperelastic Warping provides a unique alternative for
quantifying regional LV deformation during systole without the need for tags. (C) 2008 Published this website by Elsevier B.V.”
“We report on a capacitively transduced, Lame-mode resonator for real-time mass sensing in liquid. The resonators are fabricated in silicon, presenting a square plate geometry, and incorporate an integrated fluidic channel diagonally crossing the 50 mu m wide plate. Varying shapes of the buried fluidic channels (rectangular and ellipsoidal) are studied, resulting in mechanical resonance frequencies between 70 and 78 MHz. Volumes of those nanochannels range between 223 and 833 fL. For fluid-filled rectangular channels, quality factors demonstrate increasing values up to 4300 (compared with 3200 in air), when the resonance frequency x quality factor product exceeds 300 GHz. An extensive study has been carried out with the rectangular channels, showing downward frequency shifts proportional to the liquid mass, as compared with dry devices. Experimental mass responsivities for all tested devices approached 1 kHz.pg(-1). We examined different sources of dissipation, taking place in our structures, through qualitative analysis to explain the quality factor variations between dry and wet devices.