James Brice

The dramatic growth of Medicare-related medical imaging utilization-which drew the attention of rate-cutting federal policymakers and the wrath of politicians on Capitol Hill in the mid-2000s-has ended, according to a study from Thomas Jefferson University in Philadelphia. 

The year 2005 represented a turning point in that chapter for modern cross-sectional imaging, according to Dr. David Levin, a professor of radiology at Thomas Jefferson. By sifting through Medicare Part B data, Levin and Dr. Vijay Rao, the university’s radiology chair, found the compound annual growth rate for noninvasive diagnostic imaging increased 1.4% per year from 2005 to 2008, compared with 4.1% from 1998 to 2005.

“There was a dramatic flattening,” Levin said while presenting his findings Wednesday at the 2010 RSNA meeting.

The moderating trend was stronger among diagnostic radiologists than for physicians who own and operate medical imaging equipment, Levin said. An expert in physician self-referral, Levin has repeatedly singled out the controversial practice for fueling wasteful and unnecessary utilization growth.

For all forms of noninvasive diagnostic imaging, the average annual growth rate among radiologists was 0.8% from 2005 to 2008, compared with 3.4% annually from 1998 to 2005. The average annual growth rates for all other physicians for the two periods were 1.8% and 6.6%, respectively.

“Nonradiologists are basically in the business of self-referring, so it is not surprising to see that their utilization continues to grow at twice the rate of radiologists’,” he said.

By individual modality, Levin and Rao found the spectacular growth rate of CT through the first half of the 2000s slowed only slightly from 2005 to 2008, mainly because of its expanded use in emergency medicine. The number of nuclear medicine procedures, including PET, per 1000 Medicare beneficiaries actually declined slightly from 2005 to 2008, while the growth trend for MRI flattened. The utilization rate for general x-ray has changed little since the 1990s.

The same trends emerged when Levin and Rao focused on outpatient imaging. Growth rates for all modalities fell, with CT, MR, and nuclear medicine all seeing rate reductions since 2005. The CT growth rate dropped from an annual average of 9.5% in the 1998 to 2005 period to an annual average of 4.3% between 2005 and 2008. MRI procedure growth rates dropped from 13.1% to 1.9% and nuclear medicine procedure growth rates from 13.6% to 0.6% in the two time time periods.

Levin dismissed the possibility of a link between slowing growth and the Medicare rate cuts for cross-sectional medical imaging that were enacted in 2007 as part of the federal Deficit Reduction Act. He did not propose his own theory for the trend.

Publication of the results is pending in the 

Articles

The dramatic growth of Medicare-related medical imaging utilization-which drew the attention of rate-cutting federal policymakers and the wrath of politicians on Capitol Hill in the mid-2000s-has ended, according to a study from Thomas Jefferson University in Philadelphia.

Diagnostic imaging utilization slows

Cancer patients saw a four to five times greater increase in their average annual exposure to imaging-related ionizing radiation than the general population since 1994, according to a retrospective study of more than one million privately insured people in the U.S. 

Published research in general has established a sixfold increase in the average exposure to ionizing radiation for people in the U.S. since the 1980s. More than 85% of that growth was attributed to medical imaging, especially multislice CT and nuclear medicine applications. Pediatric radiologist Dr. David Brenner estimated in his 2007 analysis in the 

 (NEJM 2007;357:2277-2284) that the explosion of CT then in use in the U.S. would expose patients to enough ionizing radiation to induce 1.5% to 2% of future cancers.

These and other revelations have led to numerous efforts to modify equipment performance and medical imaging practices to reduce patient exposure and cancer risks.

Now Dr. Rebecca Smith-Bindman, a radiologist/epidemiologist at the University of California, San Francisco, has uncovered data suggesting the risk for future induced cancers may be particularly acute for current cancer patients. By examining annual exposures from diagnostic imaging involving ionizing radiation, Smith-Bindman has established that from 1994 to 2008, the average annual rate for radiation exposure for privately insured cancer patients increased four to five times faster than rates for beneficiaries who did not have cancer.

Smith-Bindman’s retrospective analysis was based on the medical imaging experience of 1,081,923 members of a large integrated health system involving eight HMOs across the country, according to Dr. Ingrid Burger, a radiology resident at UCSF. She presented the results on Wednesday at the 2010 RSNA meeting.

The UCSF research group found that the mean annual effective dose for cancer patients rose from 8 mSv in 1994 to 19.5 mSv in 2008. During the same 14-year period, the annual effective dose for non-cancer patients increased from 4 mSv to 5 mSv, Burger said. Median results were much higher than the mean findings, suggesting that a subset of patients received particularly high doses that drove up the means.

As expected, the percentage of cancer patients exposed to particularly high doses of radiation jumped markedly faster than that for non-cancer patients, Burger said. In 1994, 3.2% of cancer patients received more than 50 mSv. By 2008, 11.3% of cancer patients in the integrated system were exposed to an effective dose of more than 50 mSv, which compares with less than 2% of non-cancer beneficiaries. From 1994 to 2008, the percentage of cancer patients receiving more than 100 mSv rose from 0.4% to 3.2%.

The researchers noted that cancer patients continued to undergo imaging with elevated radiation doses long after the treatment for their cancers had ended. Cancer patients received a mean annual effective dose of 37.8 mSv in the first five years after diagnosis. Mean annual exposure decreased to 30.7 mSv for the monitoring phase (years six to 10 after diagnosis). About 10% of cancer patients in the treatment period and 7% during the monitoring period received doses of more than 100 mSv annually.

Few clear trends emerged from evaluation of the relationship between radiation exposure and the cancer patient’s age. Researchers found that the annual effective dose tended to rise with age for patients who were older than 25, but no correlations between age and exposure could be made for patients younger than 25.

“Those radiation exposures are all over the map,” Burger said. “They don’t follow any trend.”

Overall, the study underscores the need to track patients’ radiation exposure histories over time to evaluate the intensity of long-term imaging surveillance after cancer treatment, Burger said.

Cancer patients saw a four to five times greater increase in their average annual exposure to imaging-related ionizing radiation than the general population since 1994, according to a retrospective study of more than one million privately insured people in the U.S.

Growth in cancer patients’ radiation exposure exceeds that of general population

U.S. hospitals could save nearly $22 million annually by deemphasizing CT in favor of diagnostic ultrasound as the frontline imaging test for suspected appendicitis. Such a change would also spare many patients unnecessary exposure to ionizing radiation from CT, according to financial evaluation and meta-analysis by Laurence Parker, Ph.D., an imaging economics researcher at Thomas Jefferson University in Philadelphia. 

Because of its speed and accuracy, multislice CT has almost completely supplanted the traditional physical exam and diagnostic ultrasound for evaluating right lower quadrant pain suggesting appendicitis. At Thomas Jefferson University Medical Center, Parker found only 4% of patients presenting in the center’s emergency department with physical symptoms of appendicitis were referred for ultrasound. Everyone else received CT, noted Dr. Courtney Leigh Hoey, a radiology resident who presented Parker’s results Tuesday at the 2010 annual RSNA meeting.

Parker’s analysis considered the economic and radiation safety implications of shifting to diagnostic ultrasound for initial screening. His literature meta-analysis for the study found little difference between the accuracy of ultrasound and that of CT for evaluating right lower quadrant  abdominal pain. The negative predictive values of ultrasound and CT were 91% and 92.5% respectively.

That finding suggested ultrasound was accurate enough to handle initial screening. All patients with a positive ultrasound could be directed to surgery. He proposed CT be performed to confirm negative ultrasound findings.

To calculate the relative costs of current and proposed protocols, Parker drew data from the Center for Medicare and Medicaid Services’ carrier, inpatient, and beneficiary files and the Physician/Supplier Procedure Summary Master Files for 2007.

In terms of utilization, the Medicare data indicated nearly two CT scans were performed on every Medicare beneficiary who presented in the ED with suspected appendicitis. As is the case at Thomas Jefferson, only four of every 100 patients nationally received ultrasound.

Parker found the average charge per patient for abdominal and pelvic CTs was $192 per patient compared with an average $38 for a limited ultrasound exam. From that, Parker determined that $153 per patient could be saved by shifting to ultrasound as the first-line test for appendicitis.

Medicare claims data, limited to a sample of 5% of beneficiaries, identified 650 cases of appendicitis and 863 of right lower quadrant pain in 2007. By assuming that all 1513 patients were initially admitted with right lower quadrant pain and that 569 true positives would be referred directly to surgery following ultrasound because of the modality’s 87.5% sensitivity, Parker calculated a $47,766 saving for the 5% sample and a total Medicare annual saving of $955,318.

By applying these estimates to the entire U.S. population, Parker proposed that $21.8 million could be saved annually by reserving CT for only those patients presenting with right lower quadrant pain who first had a negative ultrasound to evaluate their abdominal pain.

In terms of radiation dose, Parker determined the typical patient can expect to be exposed to 12.4 mSv (± 5.2 mSv) of radiation from an abdominopelvic CT scan. By extrapolating this estimate nationally, Parker estimated that shifting to an ultrasound-first protocol would spare the population from 3.2 million mSv of exposure annually. Using data from the BEIR VII (Biological Effects of Ionizing Radiation) radiation dose estimates of health risks from ionizing radiation, he predicted that an ultrasound-first policy would avoid 363 excess cancer cases annually and avoid 182 excess deaths from a solid tumor cancer and leukemia.

Errors could have arisen in the analysis by extrapolating Medicare data, which tracks the health experience of older Americans, to the entire population, Hoey said. Parker also assumed that right lower quadrant abdominal pain was the presenting symptom for appendicitis to generate estimates. The costs and mortality associated with excess surgeries associated with the slightly lower positive predictive value of ultrasound compared with CT was not included in the cost-savings calculation.

U.S. hospitals could save nearly $22 million annually by deemphasizing CT in favor of diagnostic ultrasound as the frontline imaging test for suspected appendicitis. Such a change would also spare many patients unnecessary exposure to ionizing radiation from CT, according to financial evaluation and meta-analysis by Laurence Parker, Ph.D., an imaging economics researcher at Thomas Jefferson University in Philadelphia.

Shift to ultrasound for appendicitis could reap $21.8 million annual savings

Radiologist errors identified from an analysis of 656 imaging exams paints a unique picture describing why radiologists make errors. The analysis also points to ways such mistakes can be prevented. 

Dr. Young W. Kim, a radiologist who practices at Tripler Army Medical Center in Honolulu and Brooke Army Medical Center in San Antonio, reported Tuesday at the 2010 RSNA meeting that nearly one-third of the delayed diagnoses he studied at those two military hospitals from July 2002 to January 2010, were not only missed on the first exam, but were also not recognized on subsequent radiological examinations.

Moreover, Kim’s analysis provides insight into the very human world of radiological practice.

In Kim’s analysis, diagnostic errors are defined as missed diagnoses that are later corrected with a definitive review. Though Kim’s definition seemed abstract, the implications of botched interpretations are quite real. They are the leading cause of malpractice litigation, accounting for twice as many claims as medication errors, Kim said.

The legal liabilities associated with radiology are increasing in step with its growing influence on medical practice as a whole, Kim said. From the medical literature, the daily error rate from dictation is possibly 3% to 4% when considering all interpreted exams, but the rate is as high as 33% for abnormal studies.

Kim and colleagues identified 1279 errors examining 656 exams with delayed diagnoses collected over an eight-year period at the Tripler and Brooke Army Medical Centers. Cases were selected from difficult case conferences and the author’s files. Each case was reviewed by two radiologists. When appropriate, the case was assigned more than one type of error. Date of the original exam, imaging modality, and dates of incorrect diagnosis and corrected diagnosis were noted. Whether the diagnosis was missed on subsequent radiologic exams and the imaging technique from which the correct diagnosis was made were also noted.

Fifty-four percent of the errors arose from the interpretation of general radiography. CT and MR reading errors accounted for 23% and 9% of the errors respectively. Nuclear medicine and ultrasound contributed 7% and 1% respectively.

Under-reading was the main source of errors, Kim said; it accounted for 42% of the total. Errors associated with “satisfaction of search,” or the radiologist’s failure to thoroughly examine anatomy after seeing abnormalities relevant to a primary diagnosis, was the second most common error. These errors accounted for 22% of the total. Faulty interpretation was identified as the third leading source; it generated 9% of the total, Kim said.

Failing to notice pathology in peripheral or unexpected locations. Tunnel vision and missing pathology in the first and last images in a series (7%)

Over-reliance on the prior radiology report (6%)

A lack of comparisons with prior studies (5%)

Kim recommended the adoption of mental or written checklists of essential things to cover to reduce under-reading. Individual effort is necessary to minimize satisfaction-of-search problems by staying alert to serendipitous findings. More training and experience is the tonic needed to address faulty interpretations, he said. 

The findings from the two military centers are similar to those of published reports on radiology error rates going back to the 1940s, Kim said in response to a question from 

. The main difference is the addition of cross-sectional MR and CT in his study.