· Multiple Sclerosis: New Findings, New Hope
· Detecting Pulmonary Embolism

Multiple Sclerosis: New Findings, New Hope

Transverse nonenhanced T1-weighted MR images in a 41-year-old man with RR MS and mild to moderate physical disability. Uniformly hyperintense lesions (arrows) are seen.

A study in the September issue of Radiology has uncovered a new abnormality in the brain related to the progression of multiple sclerosis; researchers hope the information will help physicians diagnose MS more accurately and identify patients at risk for developing the disease. The study found that T1-weighted MR imaging of the brains of MS patients often reveal bright areas known as hyperintense lesions.

“This new type of lesion seems to correlate very well with the disability the patient experiences,” explained the study’s lead author, Rohit Bakshi, MD, associate professor of neurology and radiology at Harvard Medical School and director of clinical MR-MRI at Brigham and Woman’s Hospital and Partners MS Center, Boston. “The lesion is called a bright T1 lesion, which is a short way of saying it appears bright on T1-weighted MRI scans. We’ve known about bright on T2 and dark on T1, but this is new.”

Bakshi notes that the lesion should not be confused with the brightness seen on T1 after intravenous gadolinium is administered. “This is noncontrast, precontrast,” he said. “The lesion shows brightness intrinsically.”

The lesions may never have been detected before, Bakshi explains, because patients generally have many more bright T2 lesions than bright T1 lesions. “The lesion is very subtle,” he said. “It really takes a trained and experienced eye to recognize it. Now we’re hoping more casual observers will pick it up. We also don’t see as many of them. Patients on average had about three of these lesions in their brains.”

Specifically, the study revealed 340 T1 hyperintense lesions in 123 patients; lesions were more likely to be present in patients with secondary-progressive MS, and 71% of patients with secondary-progressive MS had multiple occurrences of the lesions, compared with 46% of relapse-remitting MS patients. One hundred percent of patients in the study showed bright T2 lesions, Bakshi notes.

“We really hope this will trigger additional studies to verify our results,” he said. “Another potential use would be to see if these lesions predict the response to drug therapy, and to see if they can be used to track the responsiveness of patients to drug therapy.”

The total number of T1 hyperintense lesions was closely correlated with physical disability, disease progression, and even brain atrophy. “The MS process causes the brain to shrink over time, and this finding seems to be associated with that,” Bakshi said. “But an important limitation of the study is that we don’t really know what’s causing the brightness on T1. That’s going to require getting brains at autopsy and trying to correlate those two on a one-to-one basis. So at this point we’re just speculating.”

Next up for Bakshi and his team? Additional studies to better quantify the finding. “We’re going to move to quantitative analysis,” he said. “We’ll also be looking at a longitudinal study to follow patients over time and see how this lesion changes. I think this lesion is going to turn out to be clinically important, but so far all this is unproven.”

—Cat Vasko

Detecting Pulmonary Embolism

Young women can benefit by choosing nuclear medicine approach first.

Authors of a study published in the September issue of Journal of Nuclear Medicine have concluded that young women at risk of getting a pulmonary embolism should first opt for a noninvasive ventilation/perfusion lung scan (V/Q) before undergoing a CT angiogram.

“While CTA is the major test used widely to detect pulmonary embolisms, it is associated with higher radiation risk, especially for young women of reproductive age,” said Alexander Gottschalk, a professor of diagnostic radiology at Michigan State University in East Lansing.

Although CTA may be the classic choice in diagnosing the potential life-threatening sudden blockage in a lung artery, a “very low probability” V/Q scan coupled with a “low probability” objective clinical assessment can be just as reliable as the traditional CTA, researchers said.

“The combination of a low-probability V/Q scan and a low-probability clinical assessment is extremely effective,” said H. Dirk Sostman, a professor of radiology and executive vice dean at Weill Cornell Medical College in New York and chief academic officer at the Methodist Hospital in Houston.

A V/Q scan uses radioactive material to measure ventilation and perfusion in all areas of the lungs, said Gottschalk, who for more than 30 years has performed research in studies like the Prospective Investigation of Pulmonary Embolism Diagnosis project. With V/Q scans, radiation to the breast is reduced by about 70 times on average, compared with higher-radiation procedures such as CTA, Gottschalk said.

“Our study is important for doctors—and their patients—since tests show that high radiation doses to the breast from CT, especially important in young women, may increase their risk of breast cancer,” Sostman said.

In the study, titled “Very Low Probability Interpretation of Ventilation Perfusion Lung Scans in Combination With Low Probability Objective Clinical Assessment Reliably Excludes Pulmonary Embolism: Data From PIOPED II,” Gottschalk, Sostman, and other researchers analyzed data from the large-scale, multicenter trial.

Additional co-authors include Paul D. Stein of St Joseph Mercy Oakland Hospital in Pontiac, Mich, and Wayne State University in Detroit; and Fadi Matta and Afzal Beemath of St Joseph Mercy Oakland Hospital.

Reports have shown that at least 100,000 cases of pulmonary embolism take place each year in the United States, where it is considered the third most common cause of death in hospitalized patients. According to statistics, an individual’s risk of getting a pulmonary embolism doubles every 10 years after the age of 60.

—Elaine Sanchez