Molecular Imaging Insight - March 2008 - (Page 4) ADDiTioNAL RESouRCES: Read more on Siemens PET/CT he facts are clear when it comes to women and heart disease. Cardiovascular disease (CVD) is the No. 1 killer of American women, as well as Americans over 65. CVD is the leading cause of death globally too, according to The World Health Organization that estimates 17.5 million people died from CVDs in 2005, representing 30 percent of all global deaths. Of these deaths, about 7.6 million are attributed to coronary heart disease. Because women’s heart attack symptoms often differ from those more typical in men, such as chest pain, cardiac disease is often missed in women. (Women more often experience shortness of breath, nausea, vomiting, and back or jaw pain.) The rates of cardiac disease in women remain stubbornly high compared to declining numbers in men. Many myocardial infarction warning signs are simply not identified by primary care or emergency room physicians attending to women. Also, heart attacks in women are more often fatal than in men—making early diagnosis even more important. Increasing awareness of how cardiac symptoms can differ among the sexes, coupled with the increased availability of PET/ CT and SPECT/CT and their ability to delineate both the anatomic extent and physiological severity of coronary atherosclerosis in one study present a real opportunity for improvement in diagnosis and treatment of women’s cardiac disease. T Technologies side by side Cardiologists employ a variety of nuclear and imaging technologies for diagnosing and monitoring coronary artery disease. But because of the differences in the way coronary disease tends to present in women versus men, some of these tests may be leading to the diagnosis of coronary conditions in women that may not previously have been apparent to cardiologists, says Sharmila Dorbala, MBBS, associate director of Nuclear Cardiology at Brigham and Women’s Hospital. Stress tests, in particular, have been problematic in identifying coronary artery disease in women. “More often than in men, stress tests in women lead to false positive results and we’re not entirely clear on why that is so,” says Marcelo Di Carli, MD, chief of nuclear medicine at Brigham and Women’s. “Some people have hypothesized that it is the effect of sex hormones, but we’re really not sure. The accuracy of non-imaging stress tests is lower than imaging, so we are turning more to imaging when investigating chest pain in both women and men.” Research at Montefiore Medical Center in New York has shown that 82Rubidium myocardial perfusion PET scans are useful in the subset of women with equivocal SPECT studies because PET/CT demonstrates unequivocal normal perfusion in as much as 77 percent of these patients. Overall, PET/CT studies the heart at work, revealing coronary artery disease, whether any areas of the heart suffer from impaired blood flow as well as other vital diagnostic information, points out Dorbala. PET/CT offers improved image specificity and diagnostic accuracy. Even more so than SPECT/CT, the reduction of attenuation artifacts is significant in PET/CT, leading to sharper images. PET/CT also may have the advantage in the diagnosis of smaller vessel disease that tends to be more common in women, according to Heller and Dorbala. In addition, PET/CT may offer benefit in diagnosing disease in individuals with smaller hearts; because women are smaller than men, PET/CT offers this gender-based diagnostic advantage, Heller notes. PET/CT’s ability to display blood flow information also is an advantage in diagnosing Syndrome X, chest pain that is usually associated with decreased blood flow to the heart without coronary artery disease. Syndrome X is far more common in women than men, so any imaging modality that can detect it is beneficial for women who show symptoms of either Syndrome X or coronary microvascular syndrome. Available evidence shows that myocardial perfusion PET/CT provides an accurate means for diagnosing obstructive coronary artery disease (CAD). PET/CT’s ability to provide changes in left ventricular function from rest to peak stress and to quantify myocardial perfusion provides an advantage over SPECT for multivessel CAD evaluation. Growing evidence suggests that gated myocardial perfusion PET also provides clinically useful risk stratification. PET/CT has proven useful after an unequivocal or nondiagnostic SPECT study. ER physicians, too, are increasingly ordering tests for chest pain patients with a moderate risk of myocarMolecularImaging.net Unique differences Detection of coronary disease in women is often hard to detect due to interference of breast issue and breast implants in scanning and the inability to accurately diagnose pre-test symptoms. It is widely known that women show fewer true positive scans than men who undergo SPECT stress testing. Ischemia is often overlooked in women, too. “There are developments in the PET/CT and SPECT/CT arenas that are beneficial to women, especially since women tend to be under-diagnosed for cardiac disease,” says Gary Heller, MD, director of nuclear cardiology at Hartford Hospital in Hartford, Conn. “Many physicians downplay atypical symptoms in women and women’s cardiac disease isn’t as easy to diagnose with exercise stress testing as men’s disease is. SPECT has better diagnostic ability to catch certain types of coronary disease than exercise stress-testing alone and PET/CT actually has even a higher diagnostic accuracy than SPECT in some of the studies.” PET/CT’s ability to correct for tissue-related distortion, improved image resolution and the ability to calculate blood flow in the various regions of the heart differentiate it from technologies such as cardiac CT, cardiac MRI, exercise stress tests and SPECT. Daniel Berman, MD, director of cardiac imaging and nuclear cardiology at Cedars-Sinai Medical Center in Los Angeles, Calif., calls PET/CT “the myocardial perfusion imaging test of choice, especially for large-breasted women and women with breast implants.” 4 Molecular Imaging Insight | March 2008 http://www.siemens.com/biograph http://MolecularImaging.net
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.