12 Jan PET Scanning Highlights Link Between Stress and Heart Disease
Posted at 12:15h
in Author Interviews, Brigham & Women's - Harvard, Heart Disease, Lancet, Medical Imaging, MRI, Social Issues
MedicalResearch.com Interview with:
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Dr Ahmed Tawakol[/caption]
Dr Ahmed Tawakol MD
Co-Director, Cardiac MR PET CT Program
Massachusetts General Hospital and
Harvard Medical School
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: While the link between stress and heart disease has long been established, the mechanism mediating that risk hasn’t been clearly understood. Animal studies showed that stress activates bone marrow to produce white blood cells, leading to arterial inflammation. This study suggests an analogous path exists in humans. Moreover, this study identifies, for the first time in animal models or humans, the region of the brain (the amygdala) that links stress to the risk of heart attack and stroke.
The paper reports on two complementary studies.
The first analyzed imaging and medical records data from almost 300 individuals who had PET/CT brain imaging, primarily for cancer screening, using a radiopharmaceutical called FDG that both measures the activity of areas within the brain and reflects inflammation within arteries. All participants in that study had no active cancer or cardiovascular disease at the time of imaging and each had information in their medical records on at least three additional clinical visits after imaging.
The second study enrolled 13 individuals with a history of post-traumatic stress disorder, who were evaluated for their current levels of perceived stress and received FDG-PET scanning to measure both amygdala activity and arterial inflammation.
Dr. Richard Leigh[/caption]
Dr. Richard Leigh MD
Neuro Vascular Brain Imaging Unit
National Institute of Neurological Disorders and Stroke
National Institutes of Health, Bethesda, MD
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Patients who suffer an ischemic stroke have limited treatment options. One of the reasons for this is that our treatments can sometimes make the stroke worse by transforming the ischemic stroke into a hemorrhagic stroke. In our study we identified a new piece of information that we can extract from the patient’s MRI scan that informs us on the risk of having a hemorrhage.
Dr. Lena Palaniyappan[/caption]
Lena Palaniyappan
Medical Director
Prevention & Early Intervention Program for Psychoses (PEPP)
London, Ontario
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: It is now well established that patients with schizophrenia show reduced thickness of brain's grey matter in Magnetic Resonance Imaging studies, indicating either a developmental or an acquired deficit in the amount of brain tissue. Such reductions are seen both in treated and untreated patients, suggesting that current treatments do not reverse the process of tissue loss, if at all this is occurring in patients. We wanted to study if subtle increase in brain tissue also accompanied this reduction. We observed that across the group of 98 medicated patients, reduced thickness was consistently accompanied by subtle, but nevertheless noticeable increases in thickness. Such increases were more pronounced in those with a longer duration of illness.
Dr. Vikas Gulani[/caption]
Dr. Vikas Gulani MD, PhD
Director, MRI, University Hospitals Case Medical Center
Associate Professor, Radiology
CWRU School of Medicine
Cleveland, OH
MedicalResearch.com: What is the background for this study?
Dr. Gulani: For men that have a suspicion for prostate cancer either via the prostate specific antigen (PSA) test or a digital rectal exam, the current standard of care is to perform a transrectal ultrasound (TRUS) guided biopsy to detect cancer. The problem with TRUS biopsy is that most tumors are not visible on ultrasound and hence many significant cancers are missed. At the same time this strategy detects a high number of low risk, indolent cancers, and leads to overtreatment of disease that would be better left untreated.
Diagnostic MRI and MRI-guided biopsy (cognitive, ultrasound-MR fusion, or in-gantry) have been shown to be effective in detecting clinically significant prostate cancer. However, despite these advantages there is reluctance to incorporate MRI into standard practice because it is perceived to be expensive. Our goal was to determine if this presumption is true, and evaluate the cost-effectiveness of the MRI-guided techniques most commonly used.
MedicalResearch.com: What are the main findings?
Dr. Gulani: We found that every MRI strategy we evaluated was cost-effective compared to standard biopsy. Cognitive MRI guided biopsy – where the operator performs an ultrasound biopsy based on knowledge of lesion location from the MRI – was the most cost-effective strategy compared to standard biopsy. In-gantry MRI yielded the highest net health benefits as measured in quality adjusted life years.
Dr. Nelly Tan[/caption]
Dr. Nelly Tan MD
David Geffen School of Medicine
Department of Radiology
UCLA
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Tan: Standard of care for prostate cancer diagnosis has been to perform ultrasound guided random (non-targeted) prostate biopsy (TRUS) which is neither sensitive or specific. The main limitation had been our inability to detect and localize prostate cancer through imaging.
Over the past 10 years, MRI has taken center stage for detection and localization of prostate cancer and has shown to improve prostate cancer diagnosis, risk stratification, and staging of the disease. Over the past few years, MRI guided biopsy techniques (in the form of Ultrasound-MRI (US-MRI) fusion and in-bore direct MRI guided biopsy) have been reported. We reported our performance of direct in-bore MRI guided biopsy at UCLA. Our study showed a prostate cancer diagnosis of 59% in all patients and 80% of patients with prostate cancer had clinically significant cancer.
Dr. Amin Hanjani[/caption]
MedicalResearch.com Interview with:
Sepideh Amin-Hanjani, MD FAANS FACS FAHA
Professor & Program Director
Co-Director, Neurovascular Surgery
Department of Neurosurgery
University of Illinois at Chicago
Past Chair, AANS/CNS Cerebrovascular Section
Medical Research: What is the background for this study? What are the main findings?
Dr. Amin-Hanjani: Posterior circulation strokes account for up to 30% of all ischemic strokes, and atherosclerotic occlusive disease of the vertebrobasilar (VB) is responsible for approximately one third of these cases. Symptomatic atherosclerotic VB occlusive disease is associated with a high risk of recurrent stroke despite medical therapy, in the range of 10-15% within 2 years. There have been advances in treatment options, particularly endovascular angioplasty and stenting, aimed at reverting the blockage; however these procedures themselves carry risks, and are likely to benefit only selected patients who are at highest risk without intervention. Our study, VERiTAS, aimed to determine if measurement of blood flow in the posterior circulation vessels could identify the high risk patients. Flow measurements were performed using the technique of quantitative magnetic resonance angiography (QMRA) relying on standard MR sequences and the commercial software NOVA. These flow measurements were used to designate patients presenting with symptomatic vertebrobasilar disease as flow compromised or not, and patients were then followed for a median of 23 months in a blinded fashion to determine the risk of subsequent strokes. We found that among 72 such patients, only one quarter (18 patients) demonstrated flow compromise on QMRA, but that this group had a significantly higher risk of subsequent stroke at one year, 22% vs only 4% in the other group. The hazard ratio for subsequent stroke was markedly elevated at 11.5 even after adjusting for age and other stroke risk factors.
Dr. De Brito[/caption]
MedicalResearch.com Interview with:
Stephane De Brito, PhD
Birmingham Fellow
School of Psychology
Robert Aitken Building, Room 337a
University of Birmingham UK
Medical Research: What is the background for this study? What are the main findings?
Dr. De Brito: In the last decade, an increasing number of neuroimaging studies have used structural magnetic resonance imaging (sMRI) to examine the brains of youths who show behavioural problems that include antisocial and aggressive behaviour. Those studies have mostly relied on a method called voxel-based morphometry (or VBM), which is a whole-brain and automated technique that allows researchers to objectively assess the local composition of brain tissue, such as grey matter volume. The main problem is that the findings from those sMRI studies have been quite disparate and few have been replicated, partly due to differences in sample sizes and characteristics across studies. Therefore, we set out to carry out a meta-analysis of the available data to provide a clearer account of the literature on this topic. A particular strength of our meta-analysis is that we used the original brain imaging maps (also referred to as statistical parametric maps) from 11 of the 13 studies, which makes our analysis more accurate and reliable. The final sample comprised of 394 youths with behavioural problems and 350 typically developing youths, making it the largest study on this topic to date.
Our results showed that, compared to typically developing youths, those with behavioural problems show reduced grey matter volume in the amygdala, the insula, and the prefrontal cortex. These brain areas have been shown to be important for decision-making, empathic responses, processing facial expressions and emotion regulation; key cognitive and affective processes that are shown to be deficient in youths with behavioural problems.
Dr. Wang[/caption]
MedicalResearch.com Interview with:
Shiyi Wang, MD, PhD
Assistant Professor of Epidemiology (Chronic Diseases)
Yale School of Public Health
Medical Research: What is the background for this study?
Dr. Wang: As magnetic resonance imaging (MRI) of the breast has become part of medical care, there is increasing concern that this highly sensitive test might identify health problems that otherwise would not have had an impact on the patient – so called “overdiagnosis”. However, even if MRI use leads to overdiagnosis, the main “theoretical” benefit of early detection by MRI is to prevent future advanced diseases, the prognosis of which is deleterious. A systematic literature review found that, compared to mammography and/or ultrasound, MRI had a 4.1% incremental contralateral breast cancer (breast cancer in the opposite breast) detection rate. At this point, the impact of MRI on long-term contralateral breast cancer outcomes remains unclear.
Medical Research: What are the main findings?
Dr. Wang: Analyzing the Surveillance, Epidemiology, and End Results-Medicare dataset, we compared two groups of women who had breast cancer (one group receiving an MRI, and the other not) in terms of stage-specific contralateral breast cancer occurrences. We found that after five years, the MRI group had a higher detection rate of cancer in the opposite breast than the non-MRI group (7.2 % vs. 4.0%). Specifically, MRI use approximately doubles the detection rate of early stage contralateral breast cancer, but does not decrease the incidence of advanced stage contralateral breast cancer occurrences after a 5-year follow-up. Our results indicate that nearly half of additional breast cancers detected by the preoperative MRI were overdiagnosed, which means that many of these occult cancers not detected by MRI would not have become clinically evident over the subsequent 5 years. There was no evidence that MRI use was benefiting women because the rate of advanced cancer was similar in the MRI and the non-MRI groups.
