The Daily Scan

Why understanding medical risk is key to US health reform

The McKinsey Quarterly has posted an interesting analysis: Why understanding medical risk is key to US health reform (PDF).

The fundamental nature of medical risk in the United States has changed over the past 20 to 30 years — shifting away from random, infrequent, and catastrophic events driven by accidents, genetic predisposition, or contagious disease and toward behavior- and lifestyle-induced chronic conditions.  Treating them, and the serious medical events they commonly induce, now costs more than treating the more random, catastrophic events that health insurance was originally designed to cover. What’s more, the number of people afflicted by chronic conditions continues to grow at an alarming rate.

As the nature of risk has evolved, neither the funding mechanisms nor the forms of reimbursement for health care have adapted adequately, so the system’s supply and demand sides are both hugely distorted.  Consumers are overinsured against some risks and underinsured against others; woefully short of the savings required to pay predictable, controllable expenses; and all too likely to be dealing with doctors who have big incentives to treat individual episodes of care rather than prevent illness and manage chronic conditions effectively. 

These are important — yet frequently overlooked — points in the current debate about the future of health care in the United States.  With the US government poised to spend billions of dollars to support universal access, reformers must understand this shift in the nature of risk and move to align financing mechanisms and reimbursement with it. Pouring more money into the system without modernizing it will probably worsen the health care challenges facing the country.

chalk tip #35: setting image resolution

Greetings all...

Did you know?  In ImageScope, it is easy to set image resolution.  I'm going to show you *how* easy, and I'll talk a little bit about what image resolution is, too...

First, what *is* image resolution?  Every image represents something with little dots called pixels.  Image resolution is simply the size which each pixel represents.  For example, suppose you had a picture which was 5" x 7" in dimension.  Maybe it consists of 1,500 x 2,100 pixels, so that each pixel represents 1/300th of an inch.  For this case the resolution of the image is 1/300th of an inch per pixel.  (This is sometimes called 300dpi, "dots per inch", and is a typical resolution for photographs.)  As another example, consider a digital slide with a sample area of 20mm x15mm, which was scanned with a 20X objective.  This would result in an image with 40,000 x 30,000 pixels, where each pixel represents 1/2 micron.  The resolution of this image would be .5 mpp (microns per pixel).

Okay, so how is the image resolution for an image known?  For many images including most digital slides the resolution is stored somewhere in the image, as an inherent property.  For example Aperio ScanScope instruments create SVS (TIFF) files which always contain the resolution.  When the resolution is known, it can be used by viewing tools such as ImageScope to display rulers, grids, annotations etc. using the correct dimensions.

Here's an example, a digital slide where the resolution is known:

 

Note that since the resolution is known, the ruler can be displayed with micron units and the magnification can be displayed as 40X.  Selecting Image | Resolution displays the following dialog box:

 

This shows the current image resolution is .23 microns per pixel, corresponding to an apparent magnification of 40X.

Okay, but what if the resolution is not known?  Consider the following JPEG image:

  

Note that now since the resolution is unknown, the ruler is displayed simply in "pixels" and magnification can only be displayed as a percentage.  Selecting Image | Resolution displays the following dialog box:

 

At this point, if the resolution is known, it can simply be entered!  For example if you knew this was a 40X image, you could enter 40 as the apparent magnification, or if you knew the actual resolution in microns per pixel you could enter it.  After clicking OK, ImageScope will use the resolution you have specified for rulers, magnification, etc.

It often happens that an image for which the resolution is unknown contains one or more objects of known size.  In that case, you can draw a ruler to set the resolution.  For example, consider the following gross image:

  

The resolution of this image is not known, but the image contains an image of a ruler measured in centimeters.  We can use that to set the resolution.

First, draw an annotation ruler the length of the known object in the image:

  

You will note the length of the ruler is given simply in pixels, since the image resolution is not yet known.  Now select Image | Resolution to show this dialog box:

  

Note that "Compute from Currently Selected Annotation Ruler" is selected.  Enter the length of the object measured by the ruler, in this case 5cm = 50,000 microns, and then click OK.  That's it, the image resolution will be calculated automatically from the known object size!  Here's how that image will be displayed now:

  

Note that the annotation ruler's length is now known to be 50mm.

Please try it yourself, it is easier to use than to explain!