BBI Contributing Writer

CHICAGO, Illinois As was given ample evidence during the annual meeting of the Radiological Society of North America (RSNA; Oak Brook, Illinois), the clinical practice of radiology is very much alive and well, the technological advancements in the field remain impressive and the field's commercial vitality appears sound. As is its custom, the RSNA threw open the doors to its 89th scientific assembly in Chicago's sprawling McCormick Place convention center the Sunday following Thanksgiving. The 2003 event, the world's largest international medical meeting, was a qualified success as measured by advance registrations: total registrants over 51,000, up 1% from 2002; professional registrants over 20,000, up 8% from 2002; exhibitor registrants over 25,000, down 6% from 2002.

Radiological science remains at the top of the heap, both in its many critical contributions to the practice of medicine and as a near-perfect field of application for classical high technology. Some argue that imaging methods are applied too often and with too little fiscal discipline; others mount equally persuasive arguments to the contrary. Interestingly, the RSNA meeting well reflected both perspectives.

Radiation and interventional oncology

Among the clinical highlights of the meeting was the annual Oration in Radiation Oncology delivered by Dr. Lester Peters, who was introduced as the "Michael Jordan of radiation oncology." He reported on his group's work since 1996 at the Peter McCollum Cancer Institute (Melbourne, Australia), addressing the role of positron emission tomography (PET) in radiation oncology. His clinical findings demonstrated the extraordinary benefits of PET (based upon a database of about 300 scans per month over many years), the inherent value of functional imaging, and the applicability of so-called fusion imaging notably PET/computed tomography (CT) to determine both anatomical structure and metabolic activity.

According to Peters, the benefits of PET in the application of radiation therapy to treat cancer are many. Its metabolic response predicts survivability, thereby guiding treatment plans in fact, he found that PET imaging altered treatment plans for the better 40% of the time. PET finds otherwise undetectable metastases, he said, and it can predict an ultimate cancer cure despite lingering structural abnormality. It can avoid unnecessary or futile surgeries. Peters firmly believes that PET and PET/CT deserve permanent positions in radiation oncology. His group in Melbourne now is focused on the development of new PET tracers of tumor hypoxia, an especially important metabolic marker.

An emerging, related field is interventional oncology localized, image-guided cancer therapy, an alternative to classical chemotherapy approaches. Proponents of this alternative see it as enabling the advances in image processing and functional imaging that may eventually support real-time 3-D guidance of tumor therapy. Other supporting technologies will include various methods of image-guided tumor ablation and catheter-based delivery mechanisms. One might expect a spate of new delivery products and associated suppliers supporting interventional radiologists in their continuing desire to tread on the turf of their surgeon and oncologist brethren.

The fusion imaging method combining positron emission tomography with computed tomography continues to impress. Gerald Antoch, MD, of the University Hospital of Essen (Essen, Germany), drew comparisons between PET/CT and magnetic resonance imaging (MRI) in tumor staging (T), lymph-node metastasis (N) staging and distant metastasis (M) staging of cancer. Antoch concluded that PET/ CT is a promising methodology in these processes so critical to the selection of appropriate cancer therapies. Both PET/CT and MRI exhibited particular strengths. In whole-body imaging, PET/CT was superior overall in T-staging and N-staging, and was equivalent to MRI in M-staging. Performance also varied at specific anatomical sites of carcinoma, with PET/CT leading in pulmonary metastases and MRI leading in liver and bone metastases.

Complementary reports by Drs. Ursula Jaeger of the University of Bonn (Bonn, Germany) and Mitsuaki Tatsumi of Johns Hopkins Medical Center (Baltimore, Maryland) found PET/CT to be superior to PET alone in evaluating malignant melanoma and brain tumors. Findings such as these are likely to ultimately reshape clinical practice patterns in the detection, monitoring and treatment of cancer.

Virtual colonoscopy

Progress and controversy continue in the field of CT colonography, which has become known as virtual colonoscopy since it lays claim to replacing or augmenting that now-common screening procedure for colon cancer. This frontal attack on the livelihood of gastroenterologists, the practitioners of conventional colonoscopy, is being advanced as much by public exposure as by technical gains. Perry Pickhardt, MD, of the University of Wisconsin Medical School (Madison, Wisconsin) reported his finding that virtual colonoscopy is more sensitive than conventional colonoscopy in screening average-risk patients for colon polyps, which are sometimes precursors of cancer. Using a 3-D technique and a contrast material that tagged and electronically removed residual colon contents, he claims advantages including reduced risk of colon perforation, lower cost, absence of intravenous sedation, and a shorter procedural duration (at most 15 minutes).

These recent findings conflict with the results of a meta-analysis reported in October to the annual meeting of the American Society for Gastrointestinal Endoscopy (also Oak Brook), which concluded that virtual colonoscopy (using either CT or MR imaging) was not ready for widespread use in screening for colon cancer.

While the technology's 3-D "fantastic voyage" through the colon is indeed impressive, several retarding forces against widespread adoption are worth noting. The same exhaustive and often uncomfortable colonic preparation is required. And, if noteworthy polyps are discovered, a follow-up conventional colonoscopy is required to remove them. Time and a great deal more practitioner experience and clinical data will tell if this potentially popular new methodology will be widely embraced.

Meanwhile, the new technique has demonstrated value as a follow-up to failed conventional colonoscopy, and the procedure is already reimbursed for that purpose. And work at the University of Chicago demonstrated that computer-aided detection (CAD) techniques can increase the sensitivity and selectivity of CT colonography.

Other clinical findings

Doppler ultrasound and miscarriage. An advance in Doppler ultrasound imaging offers the prospect of early screening for a leading cause of miscarriage in pregnancy: embryonic congestive heart failure. Jason Birnholz, MD, of Diagnostic Ultrasound Consultants (Oak Brook, Illinois) reported results of endovaginal ultrasound imaging on 1,530 pregnant women. His approach combined high-resolution imaging and highly sensitive Doppler. Embryonic congestive heart failure can be implicated in 40% of miscarriages. The chances that pregnancy will continue are about 95% when Doppler ultrasound confirms normal embryonic heart function at six weeks. Conversely, more than 99% of pregnancies do not continue when abnormal Doppler patterns, indicative of cardiac pressure dynamics, are noted. The potential clinical and economic implications of this new screening methodology are apparent.

Fast MRI for stroke. CT is the usual imaging method used to diagnose stroke because MRI takes longer for this time-critical diagnosis 20 minutes vs. just a few minutes. Results of a 24-patient study at the University of Cambridge (Cambridge, UK) suggest that a new, fast-MRI protocol taking just three to five minutes is a better diagnostic tool for stroke than CT and is at least as good as the conventional 20-minute MRI method. The fast protocol was enabled by one of the new 8-antenna-array head coils being developed by several MRI equipment producers. The author of the study, Jonathan Gillard, MD, reported several advantages of the new method, including clear images covering the entire head and providing vascular information useful in guiding timely thrombolytic (clot-busting) therapy, less claustrophobia and anxiety experienced by patients already agitated by their symptoms, less motion artifact, and easier facility scheduling owing to the shorter MRI examination.

Whole-body CT screening. The controversy surrounding whole-body CT screening will likely not abate following the report by Dr. Max Rosen of the Beth Israel Deaconess Medical Center (Boston, Massachusetts). He reported on a review of 653 patients who self-referred to an outpatient imaging center for whole-body screening. Among these patients, 25% had pulmonary nodules, 27% had a liver abnormality, 8% had non-obstructing kidney stones, 10% had emphysema, 6.5% had a hiatal hernia, 9% had fatty livers, 10% had liver cysts and 14% had high coronary calcium scores. In all, nearly 60% of these patients had a finding leading to a recommendation for follow-up care. But Rosen noted that most of the findings "were not particularly worrisome." His conclusion suggests that self-referred, whole-body CT screening is likely to yield minimal clinical benefit, add significantly to patient anxiety, and add substantially to healthcare expenditures if the procedure were to be commonly practiced.

CT screening for lung cancer. On the other hand, annual CT screening for lung cancer among high-risk individuals has been proven to be a cost-effective lifesaver. So concludes Claudia Henschke, MD, of Cornell Medical Center (New York), based upon findings from the 10-year Early Lung Cancer Action Project (ELCAP) and other sister studies. Among 29 cases of lung cancer diagnosed, 28 were diagnosed by screening and only one case was diagnosed in an interim period, indicating that annual screening is sufficient for detection. And, more than 80% of the diagnosed cancers were of the Stage 1 type (no larger than 10 millimeters and localized in the lungs). The cure rate for Stage 1 lung cancers is 60% to 70% but less than 5% for more advanced stages. Hence, screening high-risk populations in this case current and former smokers is effective in saving lives.

Henschke also judged the protocol to be cost-effective, as such a screening program would cost $2,500 for each patient-year of life saved, far below the cost-effectiveness threshold of $50,000 per patient-year of life saved in the U.S. For those tempted to forget, more Americans die of lung cancer than of breast, colon, and prostate cancers combined.

Radiology practice in the U.S.

According to a recent survey by the American College of Radiology (Reston, Virginia), the shortage of U.S.-based radiologists continues. While the U.S. population is growing at a rate of 1% per year, imaging procedures are growing at 4.5% per year, and many of the imaging studies are increasing in complexity.

Several trends find their source in this discrepancy. Half of all imaging practices now have some form of image management system (picture archiving and communication system) available. Three-quarters of practices have some form of teleradiology, usually within the practice or to radiologists' homes. Half have some sort of standardized dictation template, and one in six uses speech recognition software. Nurses, physician assistants, technologists, and technologist assistants assume clinical and administrative duties for which a radiologist's skills are not required. A new classification of Radiologist Assistant will be formally certified this year.

Another trend, one that was deemed helpful by some U.S.-based radiologists and threatening by others, is outsourcing of image interpretation and reporting. Outsourcing includes everything from "nighthawk" services to ease 24/7 coverage in U.S. hospitals to off-site 3-D reconstruction services to full-scale global teleradiology with credentialed (or not) practitioners located throughout the world, especially India. Some radiologists fear ramifications similar to those experienced by U.S.-based information technology (IT) workers, who have been mired in recession since 2000 and with growing frequency are finding themselves replaced by foreign IT providers.

Next month: The view from the McCormick Place exhibit floor.