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SUMMARY:Towards depth-resolved optical imaging of cardiac activity: insigh
 ts from computational models - Bernus\, O (Leeds)
DTSTART:20090720T131500Z
DTEND:20090720T133000Z
UID:TALK19135@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Optical imaging using voltage-sensitive dyes is a commonly app
 lied technique to investigate cardiac activity in perfused tissue preparat
 ions or whole hearts. It offers superior spatiotemporal resolution\, as we
 ll as the potential of obtaining simultaneous multi-modal recordings throu
 gh the combination with various other indicators (e.g. calcium). \n\nConve
 ntional epi-fluorescence imaging was initially considered as a surface map
 ping technique\, but careful interpretation of epi-fluorescence signals\, 
 taking photon absorption and scattering in to account\, has shown that suc
 h recordings can yield information about sub-surface wave propagation. The
  use of detailed bio-photonics models combined with electrophysiological m
 odels of myocardium\, so-called hybrid models\, has been instrumental in u
 nderstanding the synthesis of cardiac optical signals. \n\nWave propagatio
 n in cardiac tissue and ventricular myocardium in particular\, is a three-
 dimensional phenomenon. Building on our earlier experimental and computati
 onal work\, we are currently developing novel techniques for the 3D visual
 ization of cardiac activity using optical methods. This requires the solut
 ion of the optical inverse problem\, i.e. obtaining 3D information from a 
 limited set of optical measurements\, which is\, as is often the case in b
 io-medical imaging\, ill-posed and therefore requires regularization. Hybr
 id models of cardiac optical signals play here too an important role as th
 ey allow to assess the accuracy of the regularization scheme\, and estimat
 e the optimal spatiotemporal resolution of the reconstruction. We present 
 results from a recent study that showed the feasibility of 3D reconstructi
 on of paced activity in isolated rat hearts using an optical technique cal
 led Laminar Optical Tomography. Finally\, we report on recent work which h
 as focused on increasing depth penetration to achieve 3D reconstructions i
 n larger hearts and developing a fast acquisition system for the imaging o
 f arrhythmias during which activity is non-repetitive. 
LOCATION:Seminar Room 1\, Newton Institute
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