Monthly Archives: December 2011

Jeff Green revelation focuses attention on aortic aneurysm…

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With the revelation this past week by the Boston Celtics that their forward, Jeff Green, will be operated on soon for repair of an aortic aneurysm, attention has been focused on this potentially catastrophic condition.

WHAT IS AN AORTIC ANEURYSM?

Simply put, an aneurysm is an area of a blood vessel where the vessel wall has become weakened. This weakening may occur from age-related degeneration of the tissues that make up the vessel wall, or as a result of inherited or congenital conditions at birth. Under the pressure of blood flow, the weakened area may cause abnormal stretching and thinning of the vessel wall, and consequent enlargement of the vessel diameter. This stretching and thinning process may ultimately lead to rupture of the vessel. When the vessel involved is a major artery, such as the aorta, rupture can have catastrophic effects. The difficulty with aortic aneurysms is that they very often cause no symptoms whatsoever (are asymptomatic) until the fateful day when they rupture. In a young man such as Jeff Green, the problem is almost certainly something he has had the potential to develop from birth. One of the more common genetically inherited causes of aortic aneurysm is a condition known as Marfan’s Syndrome. This syndrome is termed a disorder of “connective tissue”. Normal connective tissues are critical to the strength and integrity of many of the structures in the human body, including blood vessels, ligaments, tendons and the connective framework of fibers in muscles, capsules, cartilage, bone, adipose (fatty) tissue, and lymphatic tissue. In Marfan’s Syndrome, the connective tissues are not healthy at the cellular level, and have a tendency to degenerate at an abnormally accelerated rate. One of the characteristics of Marfan’s Syndrome is the tendency for those affected to be unusually tall, so, it is tempting to wonder if Jeff Green may be affected by the condition (his height is reported as 6′ 9″).

 THE ANATOMY AND FUNCTION OF THE AORTA

The aorta is the “big Kahuna” of arteries in the human body, responsible for the distribution of freshly oxygenated blood to EVERY organ and living tissue, including the heart itself via the coronary arteries. Take a look at the following 3D medical animation of aortic anatomy and function to get a more graphic idea of how the aorta works.

ANATOMY AND FUNCTION OF THE AORTA

 

As is apparent from the above animated review, a rupture of the aorta anywhere along it’s length will result in a profound loss of blood flow to tissues and organs distal to (beyond)  the rupture. The higher up (or more proximal) the rupture, the greater the adverse effect on blood flow (perfusion).  Taking this concept to its logical conclusion, if the aneurysm is located at the root of the aorta at its origin in the heart, a rupture would result in a sudden cut-off of blood flow to the entire body. Following is a 3D medical animation of a rupture involving an abdominal aortic aneurysm.

RUPTURE OF ABDOMINAL AORTIC ANEURYSM

Pretty scary, isn’t it?

 

RUPTURE OF THE THORACIC AORTA AND CARDIAC TAMPONADE

As if interruption of blood flow to every organ in the body weren’t enough, there is another potentially life-threatening complication of aortic aneurysm rupture. The heart is enclosed by a membranous envelope called the “pericardial sac” or “pericardium”. This membrane serves to isolate the heart and coronary arteries from surrounding structures in the chest cavity (thorax), primarily the lungs. The pericardial attachment to the diaphragm also helps to stabilize and anchor the heart within the chest. Please take a look at the following 3D medical animation demonstrating the relationship of the heart, aota, and pericardium to get a better idea how this all works. Note especially that the first couple of inches of the aorta and its root are also enclosed by the pericardium.

ANATOMY OF THE PERICARDIAL SAC (PERICARDIUM) AND CARDIAC CHAMBERS

 

While the pericardium is rather elastic in nature, permitting expansion and contraction of the cardiac chambers (ventricles and atria), it clings relatively tightly to all surfaces of the heart, neither permitting fluid to exit, or enter, the sac. It follows, then, that an aortic aneurysm of the aortic root (or close to the root) will also be enclosed by the pericardium, and if the aneurysm were to rupture, the very brisk flow of bleeding (hemorrhage) from the point of rupture will be contained within the pericardial sac. Although the pericardial sac is capable of considerable expansion over days or weeks if there is a slow accumulation of fluid within its margins, the rapid introduction of blood into the sac, such as occurs with a sudden rupture of an aortic aneurysm, very quickly exhausts the ability of the pericardium to expand. This results in an extremely sudden (paroxysmal) increase in the pressure within the sac, which is exerted on the cardiac chambers. If not relieved on an emergent basis, the increasing pressure on the ventricles and atria causes cessation of the heart’s ability to pump blood, with chamber action coming to a complete standstill (cardiac arrest or asystole). This dangerous phenomenon is known as “acute cardiac tamponade”.  Following is a 3D medical animation that demonstrates how rapidly a rupture in the aortic root (such as may result from an untreated aortic aneurysm) leads to asystole. I produced this animation for a criminal case in which a rupture occurred from a knife blow, but the situation is virtually identical to what can happen with sudden rupture of an aortic aneurysm.

 RUPTURE OF THE AORTA WITH ACUTE CARDIAC TAMPONADE

 

TREATMENT OF AORTIC ANEURYSM – ENDOVASCULAR GRAFT PLACEMENT

From the preceeding, it can be seen that early diagnosis and treatment of aortic aneurysm is essential (prior to rupture!). There are 2 approaches to treatment, both surgical. Aortic aneurysms that are located distal to (away from) the heart, particularly those located in the abdomen, may be treated with a low-invasive procedure known as an “endovascular graft”. In this procedure, the aorta is accessed through small incisions in the femoral arteries, through which a variety of instruments, including a collapsable graft, may be introduced. After positioning across the area of the aortic aneurysm, the graft is expanded to shore up the weakened area. As the old scholar said, “a picture is worth a thousand words”. I have extrapolated this maxim to animation – “an animation is worth a thousand words”. So please take a look at the following 3D medical animation that demonstrates how an endovascular graft works far better than any verbal description.   

PLACEMENT OF ENDOVASCULAR GRAFT FOR ABDOMINAL AORTIC ANEURYSM

 

TREATMENT OF AORTIC ANEURYSM – OPEN SURGERY

Unfortunately, not all aortic aneurysms lend themselves to the relatively low-risk placement of an endovascular graft. Particularly aortic aneurysms that are located in the upper chest, close to the heart, or involving the aortic root, must be treated with an open procedure, where the chest cavity is opened. Moreover, many such cases also require that the heart be stopped during the procedure, and the patient place on a heart-lung machine (cardiopulmonary bypass). When working on, or in close proximity, to the heart, temporary cessation of the heartbeat  provides a far easier environment for the operating surgeon. While the heart is stopped, the cardiopulmonary bypass machinery draws oxygen-poor blood from the patient’s venous system, adds oxygen back in, then returns the reoxygenated blood back to to the arterial system. Following is a 3D medical animation showing how cardiopulmonary bypass works. 

CARDIOPULMONARY BYPASS
 

 Typically, patient’s undergoing open surgery will have the area of aortic aneurysm removed either partially or completely, and a synthetic graft sewn into place. As is clear, treatment of aortic aneurysm via the open surgery method is far riskier than endovascular graft placement, but relative to the often fatal prospect of an aortic aneurysm rupture, with death occurring either from hemorrhagic shock or acute cardiac tamponade, open aortic aneurysm surgery is yet another example of modern Medicine’s amazing life-saving and cutting edge capabilities.

JEFF GREEN’S AORTIC ANEURYSM

The news reports of Jeff Green’s particularly situation have been somewhat vague as to the precise nature of his aortic aneurysm. The Celtics are apparently doing a great job so far of protecting his confidentiality (and so they should). All credit goes to the medical personnel who diagnosed the condition. As mentioned earlier, aortic aneurysms are usually silent until they rupture. They are difficult, if not impossible, to detect on routine physical examination, even if thorough. Plain film xrays may or may not show the widened area of the aorta, whereas they are much more readily detected by ultrasound imaging. However Mr. Green’s aortic aneurysm was picked up, his diagnosis is a testament to the thoroughness with which the Celtic’s medical staff care for the players. Despite the lack of specificity of medical reports to the press, the term “open heart surgery” seems to keep cropping up in many of the dispatches. This inclines me to believe that Jeff’s aortic aneurysm likely involves, or is very close, to the root of the aorta where it emerges from his heart.  We can only hope (and chances are good) that Jeff’s surgery goes without incident, and that he can return to his role with the Celtics unimpaired, and so ultimately fulfill the athletic promise of his young career. Best of luck with it Jeff…  

 

 

 

From Walt Disney to 3D Medical Animation…

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Recently I had a client express uncertainty regarding the term “3D medical animation” on my company website. Did the 3D animation I produced have to be viewed with special “3D” glasses? I assured him that wasn’t the case. “Well then”, he asked, “how does the “3D” part of it work?”  And therein lies a confusing aspect of the term “3D Medical Animation, or “3D animation” in general, for the term refers to animation created with the use of virtual 3D objects, and not a “3D viewing experience”, as we have recently become accustomed to seeing at the movies. I’m hoping that today’s post will shed a little light on the difference.  

A LITTLE ANIMATION HISTORY

In understanding what modern 3D animation is, it’s helpful to look at a bit of the history of animation. Historians have traced man’s desire to graphically depict motion as far back as cave paintings from the paleolithic era, where, for example, horses were pictured with multiple sets of legs in different positons to impart the idea of motion. There are many similar examples over the millenia since, but one of the earliest devices to successfully give the illusion of motion was the Zoetrope. The first known instance of this device was in China in 180 AD, but the “modern” appearance dates to 1834. The Zoetrope consisted of a wheel, lined on its inner surface with a series of drawings, each drawing portraying an animal or characters, with slight differences in the positon of the subjects from one drawing to the next. The wheel had a series of vertical slits. Each slit permitted the viewer to see just one of the images. When the wheel was rotated, the images, as viewed in sequence through the slits, gave the illusion of motion. The number of drawings that could be placed in the Zoetrope was limited to a dozen or so, so while the effect was mesmerizing to the viewers of the time, there was limited opportunity to tell any kind of a story with the animation, and it remained just a novelty.   


 The Zoetrope

ANIMATION GOES TO THE MOVIES

At the beginning of the Twentieth Century, animation made a huge leap forward when drawings could be photographed onto motion picture film, one drawing per frame of film, and then played back at 24 frames per second. Suddenly, there was no limit to how long an animation could be, and the creative possibilities for story telling were endless. The first known example of an animated motion picture was produced by J. Stuart Blackton in 1906. Titled “Humorous Phases of Funny Faces”, it depicted what appeared to be a cartoonist drawing faces on a chalkboard, with the faces coming to life with movement.

Humorous Phases of Funny Faces – J. Blackton 1906

From that point forward, animated motion pictures evolved rapidly. Favorite characters were born -  Krazy Kat, Betty Boop, and Mickey Mouse. Sound was added; Argentinian Quirino Cristiani‘s  1931 production of “Peludopolis“ was the first to use synchronized sound. Color was added; Walt Disney won an Academy Award for ”Flowers and Trees” (1932), the first animation to use full, three-color Technicolor. Cartoons a few minutes in length gave way to feature-length animated motion pictures. Disney’s “Snow White” is easily the best known, and most successful, of the early features, but there were at least 8 feature-length animated pictures produced internationally prior to “Snow White” (none of these early features survive today). “Snow White” was also the first animated feature to use “cel animation”. In the cel technique, pictures are drawn using colored ink onto individual sheets of transparent celluloid (hence the term “cel”). The cel technique provided several major advantages; backgrounds and non moving objects in the foreground of a scene could be drawn on separate cels, as could the moving objects or characters in a scene. In this way the same background cell could be used repeatedly from one frame to the next. This saved an enormous amount of time in producing the animation, and eliminated the “jittery” characteristic of earlier animations, in which the entire scene, backgrounds, characters and all, had to be completely redrawn in each frame.  

As well, the quality of artists creating animations saw steady improvement as the years went by. Again, Walt Disney was one of the first to pioneer the hiring of top-notch artists for his studio, providing them with ongoing training in the latest animation techniques. Eventually, Walt formed the California Institute of the Arts (CalArts), in Valencia, as an institution for the training of animation artists.

“MOVING PERSPECTIVE” AND THE MULTIPLANE CAMERA

The net result of all of these innovations was a steady improvement in the look and feel of animated productions (whether they be features or shorts). But prior to the computer age, there was an essential limitation in animation that no amount of artistic talent could overcome, and that was the fact that animation was a two-dimensional medium. It was very difficult, if not impossible, to convey a feeling of moving perspective in an animation. An example of moving perspective can be seen as you drive your car along a highway, surrounded by forests in the foreground, and hills and mountains in the background. As you view the scene from your moving car, the trees closest to you have an appearance of moving much more rapidly than trees in the background; at the same time, the hills move by at a quicker pace than the mountains behind them.


2D moving perspective – objects all move at the same speed irrespective of distance from the viewer


3D Moving Perspective – note how the apparent speed of the 3D objects varies with their distance from the viewer

This type of relative movement is extremely complex when trying to draw all of these elements one frame at a time, even with the cel technique. Walt Disney understood this limitation, and, in an attempt to overcome it, ever the innovator, he invented the “multiplane camera”. The multiplane camera consisted of a device that resembled a bookshelf (see figure 1),  capable of housing 4 cel paintings inserted like shelves into the housing. The motion picture camera was attached at the top of the housing, and aimed downward through the paintings. Typically,  foreground elements or characters were painted onto the top shelf or shelves, while deeper background elements occupied the lower shelves, with the deepest elements of all on the bottom shelf. As the animation was filmed, the camera could be moved (or “panned”)  from side to side at the top of the housing. This would provide an illusion of moving perspective – elements on each painting would appear to be moving across the scene at different speeds. Foreground elements on upper paintings would appear to move more rapidly than background elements on the bottom. Walt first used this technique on “Snow White”, and for years afterward, the multiplane camera set the standard for “3 dimensionality” in animated films.Disney's Multiplane Camera

But the 3D effect created with the multiplane camera was just that – an effect. It permitted variable movement on 4 different planes within the animated scene.  It did not capture the true experience of moving perspective, in which we see an almost infinite variation in movement of objects as we pass by a scene. Let’s go back to our drive by the forest and mountains. As we cruise along, the mountains in the background appear to move at a slower speed that the trees in the foreground, but each tree is also at a different distance from us. Therefore, our perception is that each tree moves at a slightly different speed as well. Even the individual branches on a particular tree are at varying distances, so that branches closer to us appear to be moving more rapidly than those further away. The needles on an individual branch are subject to the same phenomenon, and on and on. Thus, the infinite complexity of moving perspective. 

THE COMPUTER AGE AND TRUE 3D

With the advent of the computer, it became possible to create “3D” objects in the virtual space of the computer screen. Unlike traditional 2D animation drawings, which can have height and width but not depth, these objects truly have three dimensions, and once created, can be manipulated on the screen just like an apple can be manipulated in your hand; the 3D object can be rotated, flipped top to bottom, and any side of it viewed from any angle. The manipulation of 3D objects in virtual space provides tremendous advantages over 2D when it comes to conveying information about an object to the viewer This comes in especially handy in technical or scientific animation, such as the 3D medical animation I have specialized in for the past decade. Take a look at 3D Medical Animation #1. This is an animation depicting the male pelvic anatomy. Each anatomical object was “built” as a 3D object, hence we can view these objects from any angle, and as the camera chnages perspective, the relationships of the structures are readily revealed. In this segment, the anatomical structures are viewed, first, from the front, then from the side, and finally, from above. 

3D Medical Animation 1 – Male Pelvic Anatomy 

 3D Medical Animation #2 is another example; in this case, a newborn baby with a “nuchal” umbilical cord. Note how readily the relationship of the umbilical cord to the baby can be discerned as a result of the ability to view the baby from all sides.

3D Medical Animation 2 – Nuchal Umbilical Cord

A scene built in 3D space can be populated with a whole group of 3D objects, all placed at different distances from the viewer, and all moving at different speeds with respect to each other as well as the viewer. Hence, a true experience of “moving perspective” can be achieved. The complex mathematical calculations involved in generating such a “3D” scene are taken care of by the big brain of the computer.

NOT ANIMATION IN 3D, BUT 3D ANIMATION…

So when animators use the term “3D animation”, we are generally not referring to a “3D viewing experience”, such as “Toy Story 3 in 3D”, where one feels as though the objects on the screen are jumping out at us.. We are, instead, referring to the manner in which the animation has been created, using virtual 3D objects and manipulating them in a virtual 3D universe,  rather than drawing 2D images on paper or celluloid. In other words, it is not necessary to wear special glasses to view 3D Animation, but it is necessary to don them in order to have a 3D viewing experience at the movies (or increasingly, at home on the big screen).

It may well be that in the not too distant future, all animated productions, whether for pleasure or for knowledge, will be presented as a “3D viewing experience”. I’m certain the time will come when we will be able to throw away the 3D glasses altogether, and enjoy a true 3D holographic production. For the time being, anyway, the “3D viewing experience” will be confined to the movie houses and home entertainment rooms, and my clients (and jurors)  will not be required to wear special glasses to view 3D medical animation at trial. Stay tuned…

cjs

click here to read more about 3D medical animation and use at trial…