Monday, January 28, 2013

Payam Bijari, freshly PhD'd

Congratulations to BSL's Payam Bijari, who this morning successfully defended his PhD thesis, on "Investigation of Arterial Geometry as a Local Risk Factor for Carotid Atherosclerosis", before an eminent line-up of examiners including UofT's Richard Cobbold, John Sled and Myron Cybulsky; and George Tech's Don Giddens, who wisely declined our offer of a free mid-winter trip to Toronto!

Wednesday, January 23, 2013

Ignatius J. Reilly, Gene Hunter?!?

Recently Dolores and I received a link to Viruses on Time, a blog post about virology-themed covers of Time magazine, sent to us via a mailing list we joined as part of an ESF Conference on Truth and Trust in Images, which we attended and presented at last fall. While the virus nerds were probably pondering the ethics and aesthetics of the portrayals, I was struck by the March 9, 1981 cover featuring Genetech's Herbert Boyer.  My soft-and-squishy-but-bonily-encased pattern recognition engine leapt immediately into action, and reported (and I paraphrase): "Holy Crap, that's Ignatius J. Reilly".

For those who don't know, Reilly is the protagonist of one of my favourite novels,  A Confederacy of Dunces, introduced to me by my 12th grade English teacher, who could clearly spot a misfit when she met one. Maybe it's a coincidence, but Confederacy won the Pulitzer Prize in 1981 (posthumously, another interesting, but sad, story), the same year as that Time cover.

Maybe the cover artists were one in the same (unlikely).  Or maybe the Time's cover artist was a fan of the book (possible).  Or maybe it was just "in the air".  I'd like to think it was the latter, since it faintly echoes our (and many others', of course) belief that scientific visualizations are, extricably, a product of the broader culture in which they are created.

Velocity profile skewing and Doppler ultrasound

Congratulations to BSL postdoc Jonathan Mynard, who has two papers coming out about the practical impact of velocity profile skewing in "straight vessels" (see our previous work here and here).  The first paper, in press with published by Ultrasound in Medicine & Biology, shows that it may not always be reasonable to infer flow rate waveform shape from maximum Doppler velocity traces, particular using a Poiseuille assumption. The second paper, accepted published by Atherosclerosis, highlights the substantial errors that can arise when trying to infer wall shear stresses from Doppler velocities under the common assumption of fully-developed flow.

Paper Published: High-resolution CFD detects high-frequency velocity fluctuations in bifurcation, but not sidewall, aneurysms.

Congratulations to BSL postdoc Kristian Valen-Sendstad on the publication of "High-resolution CFD detects high-frequency velocity fluctuations in bifurcation, but not sidewall, aneurysms".  Admittedly we faced some challenges getting this paper published, in part owing to our early (over)enthusiasm about the apparent association between velocity fluctuations and rupture status, but also because of our unavoidable conclusion that the bulk of published aneurysm CFD model studies may not be sufficiently resolved. This latter conclusion may be easy to dismiss because our simulations were carried out under steady inflow conditions (albeit at peak systolic flow rates), but not for long...

Tuesday, January 22, 2013

Paper Published: . Impact of T2 decay on carotid artery wall thickness measurements

Another paper from our collaborators at Johns Hopkins, this one looking at the choice of MRI acquisition parameters can affect artery wall thickness and tissue characterization.  With the help of BSL Master's student Alex Martinez, we used an analytic MRI simulation approach, which Luca Antiga and I had previously used to characterize wall thickness artifacts due to slice resolution and orientation, to confirm that decreased wall thickness measurements with increased echo time is the result of adventitial signal decay.

Paper Published: Helical flow in carotid bifurcation as surrogate marker of exposure to disturbed shear

Congratulations to BSL collaborators Diego Gallo and Umberto Morbiducci, from Politecnico di Torino, on the publication of "Helical flow in carotid bifurcation as surrogate marker of exposure to disturbed shear."  This is one of the first outcomes of work that Diego Gallo started during his stay at the BSL while he was completing his PhD (and congratulations to now-Dr. Gallo!).  

The paper shows that one can anticipate the burden of disturbed wall shear stress via cleverly constructed bulk flow parameters based on helicity, which is a measure of the way flow swirls.  A key advantage of this is that 3D (well, 4D) velocity fields can be measured directly in vivo by MRI, from which data it is (relatively) straightforward to compute helicity, whereas it's much trickier to derive wall shear stress maps from such in vivo data.

Paper Published: Comparison of carotid plaque ulcer detection using contrast-enhanced and time-of-flight MRA techniques

Congratulations to Maryam Etesami from the lab of long-time BSL collaborator Bruce Wasserman, on the publication of "Comparison of carotid plaque ulcer detection using contrast-enhanced and time-of-flight MRA techniques."  Led by former (but then current) BSL postdoc Yiemeng Hoi, our main contribution here was to employ CFD simulations to help explain the observation that some carotid plaque ulcerations, notably ones pointing "downwards", may be more difficult to spot on time-of-flight MR angiography. As shown to the left, this has a lot to do with how blood flows -- or in this case, doesn't flow -- in such ulcers.  See animations here and here.

Welcome John Harvey and Andrew Tubelli

Among Dolores' and my attempts to bring more art into the science of blood flow visualization, about two years ago we began a collaboration with Peter Coppin at OCADU, which grew to include OCADU's Bill Leeming. Now, with some seed funding from The Centre for Innovation in Information Visualization and Data Driven Design (CIV-DDD), we have added some part-time assistance from two talented graduate students, biomedical illustrators John Harvey (OCADU) and Andrew Tubelli (UofT).  Cool things are happening, will keep you posted.

Youtube channel

In my quest to bring our lab into the 21st century, I have started porting more of our videos onto BSL's YouTube channel.  Please subscribe if you are wont to subscribe to such things. We'll try to keep adding our visualizations, both old and new, as time and energy permit.

Been a long time, been a long time, ...

Well, six months later and it's time to update the blog.  As I suspect many in the blogosphere have found, the novelty of maintaining a blog soon wears off, particularly when other time (and writing) commitments rear their ugly heads.  Which I guess explains the popularity of the 140-char tweet, which seems much less daunting than a blank page. (In the not too distant future I imagine I will move our lab updates to twitter, and spare you my verbosity.)

In the meantime, I will soon post some blog, er, posts updating you on recent developments -- and by developments I mostly mean papers we've published.  These will trickle out in not any particular order, but as they come to mind.