David Ma

Looking for breast cancers with x-ray mammograms can be like searching for a snowball in a snowstorm. A new imaging technique, positron emission mammography (PEM), circumvents many of the limitations of the imaging techniques most commonly used to screen for breast cancer.

"This tool is very sensitive, specific, and it gives us great clarity and confidence in diagnosing new cancers," said Dr. Kathy Schilling, the lead researcher and director of breast imaging and intervention at the Center for Breast Care at Boca Raton Community Hospital in Florida.

Dense breast tissue and hormonal status often complicate screening and can lead to inaccurate results.

"Our oldest and most conventional tools are mammography and ultrasound," Schilling said at a news conference at the RSNA meeting Tuesday. "With mammography, particularly in patients who have dense breasts, we can miss as much as 35% of cancers that we know are in a breast."

Dense breast tissue is characterized by a large proportion of tissue that is glandular rather fatty. On mammograms, this glandular tissue appears white. However, cancerous tissue also appears white and can be mistaken for glandular tissue. With breast MRI, this problem is avoided by taking advantage of differences in cellular processes. The test is limited, though, by a high incidence of false-positives.

"You can imagine being called back and having found out that there's something abnormal on your MRI and having to have an additional ultrasound or mammography only to find out there was really nothing at all," Schilling said. "That is very disturbing for our patients."

Additionally, breast MRI is much less effective when patients are imaged at an inappropriate point during their menstrual cycle. False-positive results are often attributed to the effects of hormones in the patient.

Breast density and hormonal status will not affect PEM sensitivity or specificity when screening for cancer, Schilling said. The technique uses the metabolic differences between cancer cells and normal cells to distinguish them. By following where radioactively marked sugar accumulates, PEM can easily visualize cancerous tissue.

"I find it very easily integrated into a comprehensive breast clinic," Schilling said. "It's not difficult to learn, unlike breast MRI, and it's not affected by menopausal status or breast density."

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New mammography technique avoids limitations of older technology

CT colonography can screen for both colorectal cancer and osteoporosis reliably at minimal additional cost and time, according to a study presented Tuesday at the RSNA meeting.

Because the images are cross-sections of the entire body, CT colonography scans can also be constructed into a three-dimensional model of the spine, which can be used to measure bone mineral density, according to lead author Rizwan Aslam, an assistant clinical professor of radiology at the University of California, San Francisco. This information can then be used to determine the risk or presence of osteoporosis.

"We wanted to look at the ability of CT to not only screen for colon cancer but also allow identification of patients with osteoporosis and we thought we could crack both of them with this test," Aslam said.

A study at San Francisco VA Hospital compared the results of CT colonography scans with those of dual x-ray absorptiometry examinations, the standard imaging technique used to score bone mineral density and diagnose osteoporosis. The study compared DXA scores with CT colonography results in 30 men and five women ranging in age from 54 to 79.

Results showed excellent agreement between the DXA bone mineral density scores and the data obtained through the CT colonography study. The ability to perform colonography and bone densitometry simultaneously could be especially valuable because colon cancer and osteoporosis both affect adults over the age of 50. Doubling up the exams also means avoiding radiation exposure from a second scan.

"Virtual colonoscopy can successfully evaluate patients for osteoporosis, and colonoscopy provides valuable information on osteoporosis risk with no additional radiation or cost," Aslam said.

CT colonography diagnoses both cancer and osteoporosis

The availability of a portable CT scanner in an emergency room significantly increases the number of patients who are eligible for life-saving treatment.

In a study conducted at North Shore Medical Center in Salem, MA, stroke triage was monitored to determine the effect that rapid access to CT scans would have on treatment of stroke.

"There is only one agent available and approved by the FDA for treatment of an acute ischemic stroke, and that is tissue plasminogen activator," said Dr. David Weinreb, the lead investigator and a radiology resident at the Hospital of Saint Raphael in New Haven, CT.

Hemorrhage is a potential -- and potentially dangerous -- side effect of tPA, Weinreb said. And the drug must be administered within three hours of symptom onset.

"Usually, when patients arrive at the emergency department, they have already passed the three-hour limit," he said. "The challenge is to determine which patients are eligible for use of tPA."

A head CT must be performed before tPA can be administered, to confirm there is no bleeding. For patients who have not yet passed the three-hour time limit for tPA eligibility, a delay obtaining the CT scan reduces their chances of receiving the drug.

For one month before and four months after the installation of the portable scanner, researchers recorded how much time elapsed between a physician's request for a head CT for a stroke patient and performance of the scan. After the portable CT scanner was installed, request-to-scan times fell from an average of 34 minutes to 16 minutes.

The device is only large enough for head scans and can be kept in the emergency department. In the study it eliminated the need to move patients to the radiology department -- or even from the stretcher onto the CT table.

According to Weinreb, computer simulations of the consequences of the time reduction showed that the introduction of a portable CT scanner would double the number of patients eligible for tPA treatment.

"Based on these data, the most practical and potentially effective strategy to increase patient eligibility is to decrease request-to-scan times," Weinreb said.

Portable CT device shortens request-to-scan times, increases number of stroke patients eligible for tPA treatment

Including a patient's photo with imaging exam results produces a psychological boost that leads radiologists to take a more personal, emphatic approach to interpretation, according an Israeli study presented Tuesday at the 2008 RSNA meeting.

"Faces are special," said Dr. Yehonatan N. Turner, M.D., the lead author and a radiology resident at Shaare Zedek Medical Center in Jerusalem, during a news conference. "Research has shown that primates perceive faces differently than they perceive other objects."

As a resident, Turner noticed that he performed ultrasound examinations differently than CT examinations. He attributed the difference to the direct patient contact involved with ultrasound scanning.

"With ultrasound you can see the patient and you take on a different attitude. I wanted a method to treat each CT scan uniquely," he said.

Investigators attached photographs to the files of 315 patients referred for CT when the files were sent for interpretation. Senior radiologists read the scans twice, with an interval of three months separating the two readings.

Patients in the study were divided into three groups:

photos included during the first reading but not the second;

photos included during the second reading and not the first; and

photos not included during either reading.

"We evaluated the reports using four criteria," Turner said. "One was the number of words in the report, another was the number of incidental findings. Incidental findings were any abnormalities that were not included with the original report. We also evaluated the presence of a summary and the presence of further recommendations for treatment."

In the two groups for which photos were included during one of the readings, scores for all four criteria were higher when a photo was included compared with when they were not. The control group showed no consistent patterns.

Fifteen radiologists were also surveyed for their opinions of including a photo with patient files. All agreed that the photo helped them relate to the patient and made them feel more like an attending physician. Additionally, the photograph revealed physical features that could provide significant medical insight into possible conditions.

"These results imply that adding the photo improves radiologist performance," Turner said. "We recommend adding patients' photos to their files as a routine protocol."

Including a patient’s photo with imaging exam results produces a psychological boost that leads radiologists to take a more personal, emphatic approach to interpretation, according an Israeli study presented Tuesday at the 2008 RSNA meeting.

David Ma

Articles

New mammography technique avoids limitations of older technology

CT colonography diagnoses both cancer and osteoporosis

Portable CT device shortens request-to-scan times, increases number of stroke patients eligible for tPA treatment

Patient photos personalize imaging exams, affect radiologists’ approach to reading