|Carotid CTA showing stenosis using Vitrea software from Vital Images.|
Post-processing software allows clinicians to better track cancer therapies, plan surgeries, and diagnose heart, brain and intestinal disease. Newer tools let users subtract unnecessary structures, allowing for better evaluation of problem areas. Use of and uses for the software will only increase as data sets grow and new applications are added to the list.
In his 25 years as a radiologist, Monte Golditch, MD, of Memorial Health System in Colorado Spring, Colo., has seen the evolution from “taking a simple x-ray to where we’re at now which is heavily computer-oriented, very high-tech with the ability to cut, dice and slice the body in many different facets. It’s really made a difference. I’m a much better radiologist now than I ever could have been regardless of my own skills and experience because of the ability to use higher level computer analysis and multiplanar reconstructive imaging to glean more data and extract greater information than was ever possible before.
Golditch uses Vitrea software from Vital Images, which helps him present information to other clinicians in “a much more understandable way. When we process a case, we can depict the boiled down essence of our processing and our findings. One picture may do more than all of my written words to explain what’s happening [with the patient].
Golditch uses advanced visualization for vascular work, such as aortic, thoracic or abdominal aneurysms, carotid dissection, trauma cases, aneurysm searches for patients with severe headaches, and long-leg runoff studies for evaluation of peripheral artery disease and peripheral insufficiency. For cardiac patients, Vitrea lets Golditch analyze the coronary arteries. “It’s very sophisticated and very helpful. Noninvasive coronary CT evaluation would not have been possible without the software. Whenever we evaluate a case on Vital, we always extract more information that is useful and helpful. I can be more confident of a rendered diagnosis having used the software.
Even more uses
To Ted Wen, MD, pediatric radiologist at Presbyterian Hospital, a Texas Health Resources facility in Plano, Texas, “3D and 4D imaging is an invaluable tool. We use it everyday.
Wen, who works with VolumePro software from TeraRecon, studies vessels without having to perform an invasive angiogram, and several-day hospital stay. “With a simple peripheral IV access in a vein, we use a CT scanner or MRI scanner and can perform images at a thicker slice for lower radiation exposure and a very fast exam [a few minutes] and then process the images to as thin as 0.625 mm. With this raw data, we then analyze the images on a 3D workstation and can generate not only beautiful images but potentially more accurate images than simply viewing the images 2D.
In a recent brain aneurysm case, on 2D imaging Wen initially thought the aneurysm originated off the anterior cerebral artery. However, when he viewed the images in three dimensions, he could see that the aneurysm originated off the anterior cerebral artery as well as the anterior communicating artery. That altered the surgical planning.
Wen also uses 3D imaging for all complex fractures “where we generate images that look like the actual bone with color and show all of the fracture fragments at different angles. The orthopedic surgeons find this very helpful. We can even sequentially subtract the skin to show the muscles, then subtract the muscles to show the vessels and nerves, then subtract the vessels and nerves to show just the bones.
Craniosynostosis—premature fusion of the skull sutures in infants—calls for a 3D image of the skull to aid in finding very short segments of the suture that may be fused. That gives craniofacial surgeons a roadmap of where to operate.
Wen also uses 4D imaging to study the heart, such as watching how the heart contracts. That helps him quantify the amount of blood being pumped by different chambers and also assess valve function. “We can study the entire coronary arteries with a five-heartbeat scan and generate 3D images of the coronary arteries, then fly-through the vessels as well as fly 360 degrees around the vessel looking for peripheral plaques that may be missed with a routine angiogram.”
Hybrid imaging usage
Ninety percent of the business done at Northern California PET Imaging Center is oncology, says Steven Falen, MD,PhD, medical director. The facility installed TrueD from Siemens Medical Systems last June.
“PET/CT is a very significant tool for diagnosis, staging and monitoring of therapy for various cancers,” he says. Other elements of the group’s work include PET/CT for evaluation of cardiac viability and brain imaging for dementia.
Because there can be different chemotherapy regimens for specific cancers, monitoring the response to chemotherapy is important. “In the past, people could be treated for several months only to find out that the chemotherapy hadn’t worked. Having the flexibility to display pre- and post-therapy imaging at closer intervals allows the ordering physician to change the therapy to better treat the disease.
PET imaging with a radiolabeled glucose analogue allows radiologists to see focal areas of increased glucose metabolism which can be associated with cancer. Fused with CT, these imaging studies allow physicians to pinpoint disease in the body. The fused images “tell us about the staging of the disease, which is one of the most important questions to answer.” For example, if a patient has a lung nodule which turns out to be cancer, and there is no other disease, then surgery may be curative. PET imaging may show disease elsewhere in the body, even if the CT appears normal, requiring chemotherapy. The information PET/CT provides can make a big difference in how the patient is treated.
TrueD lets Falen look at multiple studies at different time points, another important tool for tracking cancer. A lung nodule that has been followed for months or years may not look significantly changed from the most recent imaging study. But when compared to several earlier studies, the radiologist may see that it is slowly growing.
The volume of data generated with combined metabolic and anatomic imaging is large. Multidetector CT can generate thousands of images in each study which are fused with metabolic imaging and examined in different imaging planes and in different CT windows and levels. Good 3D imaging and volume analysis software can significantly ease the process of evaluating so many images allowing the radiologist to focus on what is important.
Into the future
“As time goes on, [advanced visualization] software is getting much more user friendly,” says Golditch. That could result in improving radiologist efficiency or could allow for technologists to participate more since there would be less margin for error because the computer does more of the work.
Wen sees an exciting future for advanced visualization. Straight out of science fiction, a virtual hologram initiative is underway which would allow radiologists and surgeons to view a life-size 3D or 4D image of the patient and rotate the images with their hands. Researchers also continue to work on decreasing radiation exposure and the length of time a study requires, as well as improving the resolution of the images.
|Tracking the progression of Alzheimer's|
Robert Bartha, PhD, Ivey BMO Financial Group Scientist in Brain Disorders Imaging at the Robarts Research Institute and associate professor, University of Western Ontario in London, Ontario, Canada, uses Cedara software to study brain ventricle volumes and Alzheimer's disease. He and his team started working with Cedara about two years ago.
Alzheimer's victims experience a lot of degeneration over time in their brain tissue. "If you were to look at the patient over the course of a year or two, you would see parts of the brain essentially dying away or shrinking," says Bartha. "Ventricles are adjacent to many areas of the brain affected by disease. When brain tissue shrinks away, the space of the ventricles gets larger. Using the ventricles themselves, we can get indirect measurement of atrophy in the brain."
Bartha and his group collaborate with a geriatric clinical trials group lead by Dr. Michael Borrie at Parkwood Hospital in London Ontario, and use both anatomical imaging and MR spectroscopy to measure chemicals in the brain. "We've been acquiring imaging data on a group of Alzheimer's patients over time and used the software that Cedara has created to study those patients."
The group also is involved in a much larger, multisite trial—the Alzheimer's Disease Neuroimaging Initiative (ADNI), which is sponsored by industry and the National Institutes of Health. Scientists have access to the imaging information of about 800 individuals from more than 50 sites. ADNI follows normal elderly patients, patients with Alzheimer's and patients classified as having mild cognitive impairment which might be the phase before Alzheimer's sets in.
Bartha and his team have downloaded images and begun to measure ventricle volumes to discriminate between the groups. "If you look at the rate of change over time, comparing from baseline to six months later, we find that the ventricles of people with Alzheimer's expand at a much higher rate than those with mild cognitive impairment or those people aging normally. Cedara software allows us to do this and do it quickly."
The goal is to measure disease progression which will ultimately result in early detection. Bartha also is interested in measuring response to treatment. One question to answer is whether a drug that relieves symptoms also modifies the disease itself. "That could potentially let us evaluate which drugs are working on an individual basis."
Bartha says his group's work has been presented at several conferences. There is a sense of urgency, he says, because "Alzheimer's is a monumental problem that, if we don't find something quickly to help, it's going to cause a major depletion of funds in our healthcare system."