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[SCIRUN-USERS] Re: question on Utah torso model's anatomy correctness


Chronological Thread 
  • From: Rob MacLeod <macleod@cvrti.utah.edu>
  • To: Hongyu Sun <sun.hongyu@gmail.com>
  • Cc: Rob MacLeod <macleod@cvrti.utah.edu>, dataset-users@sci.utah.edu, scirun-users@sci.utah.edu
  • Subject: [SCIRUN-USERS] Re: question on Utah torso model's anatomy correctness
  • Date: Fri, 10 Feb 2006 06:51:14 -0700
Hi,

First, the original source of the geometry was MRI, as you have read.  However, our interest in the bone data came later and they were not visible enough in the MRI to extract from there.  Instead, we acquired standardized rib and spine geometry and fit them to the torso model.  

With that said, there is considerable variation among patients with regard to heart shape and even location.  Some hearts are long and relatively narrow while others sit higher and are larger in a transverse slice.  The variation you have spotted between the textbook and the Utah torso is, I believe, well within that normal range of variation.

Finally, gating to the R wave does not ensure systole in the images of the heart for a couple reasons.  The first reason is that electrical and mechanical systole are not aligned in time.  Each cell of the heart experiences a delay between electrical and mechanical excitation, up to 200 ms in fact..  The result is that the R wave occurs during end diastole of the mechanical cycle, i.e., well before mechanical systole.   Even more important, using the R wave to gate the image acquisition does not mean that all images have to be captured at the time of the peak of the R wave; rather the peak of the R wave provides a common reference so that acquisitions from different beats can capture the same phase of the heart cycle.  The actual acquisition moment can be offset from the time of the R wave using a simple delay, i.e., each acquisition can occur with the same delay from that peak of the R wave.

I hope that with this information you can see that the Utah torso geometry can, indeed, be trusted to represent  reasonably the geometry of an adult human torso.  Just as with the visible human data, this is only one specific case and there are simply not enough data available to begin to create a true atlas that specifies the ranges of normal anatomy of the entire torso.  There are atlases like this of the brain but I don't know of any other organ system that has received enough attention to begin to quantify anatomical variation.

Best regards,

Rob MacLeod




On Feb 10, 2006, at 1:31 AM, Hongyu Sun wrote:

So all MRI images for heart is gated with R wave. So the heart is smaller then. If that's the reason, it will make sense. Just was worried that if my Matlab code is right or not.
 
Thank you.

HS
 
On 2/10/06, Hongyu Sun <sun.hongyu@gmail.com> wrote:
Sorry I was careless to send large files. I put them on my website.

https://mywebspace.wisc.edu/hongyusun/web/Utahtorso/

Using the .fig file, you could rotate it in Matlab. I thought I could trust the Utah torso model since it seems from NIH. Please give me a reference of the validity of this model.

Look forward to your response,

Hongyu


On 2/9/06, Hongyu Sun <sun.hongyu@gmail.com > wrote:
Hi,

I am using the Utah torso high resolution text file.

I wonder how the torso was created? Is it based on Visible Human data?

I looked the heart versus rib relation.
I am attaching .jpg file and .fig file about  the front view from the Matlab drawing the front ribs (ribs with y<-5) and heart muscles and heart chambers.

Compared with normal human anatomy, for example,
http://education.yahoo.com/reference/gray/illustrations/figure?id=1216

I am afraid the heart's location is a bit low than normal.

This is a critical question. Could anybody give an explanation on the source of Utah torso data? If my Matlab code is wrong, could you show me the heart vs. rib view you draw from the dataset?

Look forward to your reply,

Thank you very much,

Hongyu






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