RSNA News - October 2004

Scientific Program Reflects RSNA 2004's Role as a Global Forum

Reflecting this year's theme, "Radiology's Global Forum," the scientific program for RSNA 2004 will include more than 2,100 scientific paper and poster presentations by researchers from around the world.

The RSNA 2004 scientific program provides cutting-edge research in every aspect of the art and science of medical imaging and reflects research trends that will affect the future of radiology.

In the past, ablation was used to treat primary liver tumors and liver metastases, and now we see it used for tumors in the genitourinary tract and for patients with breast, lung and bone tumors. —George S. Bisset III, M.D.

George S. Bisset III, M.D., RSNA Scientific Program Committee chairman and vice-chair of the Department of Radiology at Duke University Medical Center in Durham, N.C., says the abstracts submitted for presentation this year show several important trends:

• The use of functional MR imaging (fMRI) to evaluate areas of the body other than the brain, including the heart and abdomen.
• Expanded use of ablation techniques outside the liver, further moving radiology beyond a diagnostic tool to a treatment modality. "In the past, ablation was used to treat primary liver tumors and liver metastases, and now we see it used for tumors in the genitourinary tract and for patients with breast, lung and bone tumors," says Dr. Bisset. "It used to be mostly radiofrequency (RF) ablation, but now other ablation techniques are also being employed, including cryoablation and laser thermal ablation."
• Greater use of hybrid imaging with positron emission tomography (PET) combined with CT or MR to provide both functional and anatomic information for the diagnosis and evaluation of tumors.
• New research on angiogenesis imaging to evaluate tumor activity and identify early tumor growth.

The members of the RSNA Scientific Program Committee and its 16 subcommittees reviewed more than 6,400 scientific abstracts submitted for presentation at RSNA 2004. Over the summer, committee members accepted for presentation about 1,600 scientific papers and 500 scientific posters.

Subspecialty Abstracts

New this year is a subcommittee of the Scientific Program Committee devoted to emergency radiology. "A lot of papers dealt with the use of multislice CT to replace radiography in applications where radiography has traditionally been used, such as to evaluate multiple trauma in the spine, lumbar and thoracic region, chest and pelvis," says Stuart E. Mirvis, M.D., subcommittee chairman.

"Multislice is faster and more sensitive than radiography, and it can be reformatted to provide better image quality," he adds. "Another trend is greater use of multislice CT angiography in assessing acute trauma in the aorta, cervical vessels, extremities and abdomen, thus eliminating the need for angiography."

Valerie P. Jackson, M.D., chair of the breast imaging subcommittee, points to a study of ultrasound-guided cryotherapy for the treatment of breast cancer. The study found that cryotherapy completely destroyed tumors smaller than 15 mm in diameter. "Cryotherapy has potential for treatment of breast lesions without the need for surgery," she notes.

Another study she finds noteworthy is one describing the use of ultrasound-guided fine-needle aspiration to preoperatively stage the axilla in women diagnosed with breast cancer. "Axillary staging for breast cancer patients has become less and less invasive over the years," she says. "Ultrasound-guided fine-needle aspiration may be an accurate method for assessing axillary lymph nodes and could help determine which patients need axillary node surgery."

In the realm of cardiac imaging, subcommittee chair Melvin E. Clouse, M.D., notes an abstract describing MR planimetry to quantify aortic valve stenoses using steady-state free precession and gradient-echo fast low angle sequences. "This fast MR imaging technique for measuring the aortic valve area offers a fast, noninvasive technique to evaluate the degree of aortic stenosis, and it avoids the more invasive method of transesophageal echo," Dr. Clouse says.

He also highlights an abstract looking at the use of multidetector CT (MDCT) to assess the morphology of coronary artery lesions in patients who recently had unstable angina or a myocardial infarction. "MDCT was able to detect non-calcified plaque," he explains. "This is an exciting advance in comparison with invasive intracoronary ultrasound. MDCT was able to measure the length of the plaque, the remodeling index of the coronary artery and the degree of stenosis at the site of the obstructing plaque."

The chair of the subcommittee on chest radiology, John Mayo, M.D., says one important abstract in his area is on the use of low-dose CT as a screening tool for lung cancer. The study, called the International Early Lung Cancer Action Project, conducted at 33 institutions around the world since 1993, concludes that with annual CT screening, a high percentage of Stage I lung cancers are discovered.

Dr. Mayo also identifies as important an abstract describing the use of percutaneous RF ablation alone or in conjunction with chemotherapy and radiation therapy to treat primary or metastatic lung tumors. The researchers concluded that the technique appears to be safe and technically feasible.

In the subspecialty of gastrointestinal radiology, subcommittee chair Jay P. Heiken, M.D., identifies studies using RF ablation to treat liver metastases. "These large-scale studies demonstrate that RF ablation of liver metastases in patients with colon cancer is an effective treatment. In patients with small solitary lesions, the results are equivalent to those reported for surgical resection," he says.

Dr. Heiken also notes a paper showing that RF ablation of small hepatocellular carcinomas may be as effective as surgical resection in prolonging patient survival. He also highlights a paper demonstrating the feasibility of performing CT colonography, or virtual colonoscopy, without bowel preparation.

This is the first real demonstration of volumetric measurements by MR imaging of diseased organs. It demonstrates the accuracy and ability of MR imaging to track small changes in cyst size as a measure of disease progression. —Philip J. Kenney, M.D.

The chair of the subcommittee on genitourinary radiology, Philip J. Kenney, M.D., identifies as important a large study, funded by the National Institute of Diabetes & Digestive & Kidney Diseases, of the use of MR imaging to assess the progression of polycystic kidney disease. "This is the first real demonstration of volumetric measurements by MR imaging of diseased organs," says Dr. Kenney. "It demonstrates the accuracy and ability of MR imaging to track small changes in the cyst size as a measure of disease progression."

He also finds significant a study showing percutaneous RF ablation of solid renal tumors to be a promising minimally invasive treatment for patients with high-risk medical conditions. The study's authors concluded that long-term follow-up of the treated patients is necessary to confirm the results of this therapy.

Kimberly Applegate, M.D., M.S., chair of the subcommittee on health services, policy and research, says a study of the causes of malpractice suits in radiology should be of great interest to radiologists. Researchers examined the records of 5,497 radiologists from 42 states and found that 51 percent of the radiologists had a history of at least one malpractice suit and that the vast majority of the suits involved a failure to diagnose.

Dr. Applegate also highlights a study on how the obesity epidemic in the United States impacts the ability of radiology departments to provide diagnostic imaging. The authors of the study concluded that changes in the American body habitus over 14 years have increasingly affected the ability of departments to provide quality images and accurate image interpretations. "We are getting fatter and that may limit access to imaging," Dr. Applegate says.

George Y. El-Khoury, M.D., chair of the subcommittee on musculoskeletal radiology, points out a study using MDCT to perform a virtual autopsy for cases of unnatural deaths and to compare the results with subsequent autopsies. MDCT was shown to have a high correlation with autopsy results and was able to provide additional information, such as the distribution of gases from small pneumothoraces, in free abdominal air and after open skull trauma.

Dr. El-Khoury also notes a study demonstrating the practicality of using 3-Tesla isotropic 3D imaging to evaluate knee injuries. "Isotropic proton density 3D imaging of the knee will likely change the way knee injuries are imaged in the future," he says. "Images are acquired in one plane, but they can be viewed in any arbitrary plane."

Robert M. Quencer, M.D., chair of the subcommittee on neuroradiology/head and neck imaging, finds noteworthy a study of MR proton spectroscopy to evaluate the impact of highly active antiretroviral therapy (HAART) on the character and intensity of metabolic changes in the brains of HIV-infected patients. "MR spectroscopy can document the effectiveness of HAART on returning brain metabolites to more normal levels in HIV-positive patients who are not symptomatic," he says.

Another study Dr. Quencer highlights is one showing that fMRI can image varying responses to glucose loading in the hypothalamus of obese and lean humans. "Given the current obsession with obesity in this country, this paper should have national recognition," he says. "To my knowledge, this is the first paper to address functional imaging differences between obese and non-obese people."

Jack A. Ziffer, M.D., chair of the subcommittee on nuclear medicine, says the most striking trend in his area is the use of PET/CT hybrid imaging. "Superb work is being done with PET/CT hybrid imaging in terms of diagnosing and staging cancers," he says. "The number and quality of papers submitted are unbelievable."

The importance of this trend is that "nuclear medicine is clearly changing," says Dr. Ziffer. "Nuclear medicine performed in isolation, without the benefit of correlative anatomic imaging, is something of the past. PET scans reveal the physiology of the cells being studied, whether normal or abnormal. CT tells whether the cells are normal or abnormal in terms of size and sometimes density. Combining PET with CT gives incredible sensitivity, particularly in detecting and localizing cancers, and may cut the image acquisition time in half."

In the field of radiation oncology and radiobiology, subcommittee chair Chul Soo Ha, M.D., says that a significant number of abstracts deal with the use of intensity-modulated radiation therapy (IMRT) to treat prostate cancer. "IMRT provides a very localized treatment for prostate cancer, and data have been accumulating on its effectiveness," he says.

Dr. Ha also notes a study of the use of radioimmunotherapy in the treatment of lymphoma. "More and more data are coming out on radiolabeled antibodies that are conjugated with radioactive iodine or radioactive yttrium," he says. "They are injected into patients and bind to the tumor cells to help kill them."

Donald P. Frush, M.D., acting chair of the subcommittee on pediatric radiology, points to a study using diffusion tensor imaging (DTI) to evaluate white matter in the brains of children with attention-deficit hyperactivity disorder (ADHD). "We believe this study is the first DTI study to report localized hemispheric white matter bundle abnormalities in ADHD," the study authors wrote.

Dr. Frush also notes a study comparing the results of PET/CT imaging for pediatric cancers with those of contrast-enhanced CT. The authors concluded, "While longer term follow-up of these patients is required to determine the accuracy of the method, our data suggest that FDG PET/CT offers the most accurate methodology for assessment of physiologically active pediatric malignancies."

This study indicates that the next generation of breast imaging is multimodality. —Maryellen Giger, Ph.D.

According to Maryellen Giger, Ph.D., chair of the physics subcommittee, one noteworthy abstract reports a new integrated breast-imaging system that allows simultaneous acquisition of x-ray and ultrasound images during a single breast compression. "This study indicates that the next generation of breast imaging is multimodality," Dr. Giger says.

In addition, she highlights a study showing the promise of a computer-aided diagnostic method using ultrasound images from scanners made by two different manufacturers to detect breast lesions. "This paper indicates the potential role of computer-aided diagnosis in ultrasound imaging in the diagnostic workup for breast cancer," she explains.

As for the subspecialty of radiology informatics, subcommittee chair H. Hugh Hawkins, M.D., identifies as important an abstract describing computer software that allows CT colonography to be done without traditional bowel-cleansing preparation. The software enables endoscopic views of the colon after electronic cleansing of the bowel.

Dr. Hawkins also highlights an abstract showing a role for CT and 3D modeling in analyzing art, specifically the structure of a 5,300-year-old Egyptian mummy mask to help stabilize and restore the mask. "This is an example of applying radiologic technology to art," he says.

Myron A. Pozniak, M.D., chair of the subcommittee on ultrasound, notes a number of abstracts on elasticity imaging. "Ultrasound elasticity imaging allows one to look at differences in tissue strain to differentiate an area of tumor from an area of normal tissue," he says. "The technology is being applied to breast tissue and the thyroid gland."

Another area of interest reflected in the abstracts is in dynamic contrast-enhanced ultrasound imaging of the liver. "This is by far the hottest topic in ultrasound," Dr. Pozniak says. "The studies are mostly from Europe and Asia because the United States still does not have FDA approval for this application of ultrasound contrast. This technology can be used to differentiate benign from malignant lesions in the liver."

Finally, in the area of vascular and interventional radiology, subcommittee chair Anne C. Roberts, M.D., comments on the increase in the number of abstracts devoted to the use of RF ablation to treat malignancies in the liver, kidneys, lungs and bones. "This is a new way of treating patients with cancer who have solitary lesions and may not need full-blown chemotherapy or do not have surgical options," she says. "It looks like a good way to prolong life with minimal morbidity."

A lot of studies in her area also focused on multidetector CT vascular imaging. "MDCT is being used in particular to evaluate peripheral vascular disease," she notes. "It avoids the use of a catheter for an arteriogram to visualize the vasculature. There is also a lot of interest in doing the same kind of imaging with MR, especially in evaluating kidney function."

A visual tutorial on how to use the online RSNA Meeting Program is in the RSNA.org column.

RSNA 2004 Scientific Program Committee

(Back row, from left) Jay P. Heiken, M.D., Anne C. Roberts, M.D., Donald P. Frush, M.D., Gerald D. Dodd III, M.D., Vice-Chairman, George S. Bisset III, M.D., Chairman, Robert M. Quencer, M.D., Myron A. Pozniak, M.D., David R. Pickens III, Ph.D., AAPM Liaison, Jack A. Ziffer, M.D., Ph.D., Georges Y. El-Khoury, M.D., John R. Mayo, M.D., and Stuart E. Mirvis, M.D. (Front row, from left) Valerie P. Jackson, M.D., Chul Soo Ha, M.D., Kimberly E. Applegate, M.D., M.S., and H. Hugh Hawkins Jr., M.D. Not pictured: Melvin E. Clouse, M.D., Maryellen L. Giger, Ph.D., and Philip J. Kenney, M.D.