[ RadSafe ] Cumulative Radiation Exposure Shows Increased CancerRisk for Emergency Department Patients

Thu May 29 12:44:40 CDT 2008

The following is yet another "new" article:
 Public release date: 29-May-2008

Contact: Bonnie Prescott
bprescot at bidmc.harvard.edu
617-667-7306
Beth Israel Deaconess Medical Center 

New method effective in detecting dangerous coronary plaque
Non-invasive CT scan proves safe and accurate in uncovering early signs of heart disease
BOSTON – A significant number of patients who suffer a heart attack never have any warning signs. For many of these individuals, the source of the problem is noncalcified plaque, a buildup of soft deposits embedded deep within the walls of the heart’s arteries, undetectable by angiography or cardiac stress tests – and prone to rupture without warning.
Now a new noninvasive method has shown success in detecting and measuring noncalcified plaque. In a pilot clinical study led by investigators at Beth Israel Deaconess Medical Center (BIDMC), the technique -- voxel analysis used in conjunction with MDCTA (multi-detector computed tomography angiography) – was shown to be equally as effective as catheter coronary angiography in identifying patients at risk for heart disease. Reported in the June 2008 issue of the American Journal of Roentgenology (AJR), the new findings may help doctors monitor the effects of medical treatment to reduce patients’ risk of atherosclerosis and heart disease. 
“The importance of quantifying plaque is critical because total plaque burden is considered the most important predictor of coronary events,” explains the study’s senior author Melvin Clouse, MD, PhD, Emeritus Chairman of the Department of Radiology and Director of Radiology Research at BIDMC and Deaconess Professor of Radiology at Harvard Medical School. “Furthermore, the rupture of soft noncalcified plaque has been implicated as the cause of heart attack.”
Exercise stress testing and coronary angiography, the standard methods for diagnosing atherosclerosis and heart attack risk, both work by visualizing the lumen, the channel through which blood flows.
However, because the lumen also increases in size as plaque progresses, coronary artery disease may go undetected until late in the disease process. And, adds Clouse, “Because soft plaque buildup may not significantly narrow the lumen, conventional angiography and stress tests fail to provide a complete picture of plaque accumulation.”
The investigators set out to evaluate a new method of plaque assessment using multidetector computed tomography angiography (MDCTA). Unlike coronary angiography, in which a catheter is threaded through the femoral artery and up into the heart, MDCTA is not invasive. The CT scanning method, comprised of 64 separate scans, provides a detailed cross-sectional view of the blood vessel wall based on the amount and volume of blockage present. Its ability to differentiate plaque density makes it particularly useful in distinguishing between stable plaque and unstable plaque.
“The latest MDCT scanners have made it possible to detect noncalcified plaque,” explains Clouse. “However, due to a number of technical and physiologic factors, accurate and reproducible measurements of this plaque was difficult and time-consuming. We, therefore, developed a new technique that would overcome these obstacles.”
The researchers analyzed 41 normal and eight abnormal arterial cross sections with noncalcified plaque selected from 10 patients undergoing MDCTA for percentage of stenosis and plaque volume using a voxel analysis technique, in which density values are measured to identify the boundaries between epicardial fat and the outer arterial wall and between the inner wall and the lumen. 
“Voxel analysis estimates the volume of plaque in a blood vessel based on a range of volumetric densities,” explains Clouse. Within the selected volume, the number of voxels having a density within the range of plaque is established, from which the volume of plaque is then estimated. (In CT scans, voxel values are Hounsfield units, which give the opacity of material to X-rays.) The detailed measurements – nearly 2,300 in total – provided physicians with a detailed picture of the coronary arteries and surrounding areas.
“By plotting a voxel histogram across the arterial wall, we were able to measure the amount of plaque, as well as the narrowing of the artery,” explains Clouse. Importantly, he notes, the technique additionally defines the outer boundary of the adventitia, the connective tissue surrounding the artery. Though considered extraneous to the artery, the adventitia appears to play a critical role in the disease process.
“Using this new method, we hope to be able to be able to better assess the effects of medication treatment and lifestyle interventions in treating atherosclerosis,” says Clouse, who as a member of a team of clinical investigators will study the effects of lifestyle intervention (diet, exercise and omega-3 fatty acid supplement) or salsalate medication compared to placebo on coronary artery calcification as assessed by MDCTA. (See description below.)
###
Coauthors of the AJR report include Vassilios Raptopoulos, Adeel Sabir, Norihiko Yoshimura, and Shezhang Lin of BIDMC’s Department of Radiology; Francine Welty and Pedro Martinez-Clark of BIDMC’s Department of Cardiology; and Jacqueline Buros of the PERFUSE Core Laboratory and Data Coordinating Center, Harvard Medical School.
Beth Israel Deaconess Medical Center is a patient care, teaching and research affiliate of Harvard Medical School and consistently ranks in the top four in National Institutes of Health funding among independent hospitals nationwide. BIDMC is a clinical partner of the Joslin Diabetes Center and is a research partner of the Dana-Farber/Harvard Cancer Center. BIDMC is the official hospital of the Boston Red Sox. For more information, visit www.bidmc.harvard.edu.
Funded by the National Heart, Lung and Blood Institute (NHLB), the trial will be conducted at Beth Israel Deaconess Medical Center, Joslin Diabetes Center and Tufts New England Medical Center. Leading the TINSAL-CVD study are Allison Goldfine, MD, Director of Clinical Research at Joslin Diabetes Center; Steven Shoelson, MD, PhD, of Joslin Diabetes Center; Ernest Schaefer, MD, of The Jean Mayer USDA Human Nutrition Center on Aging at Tufts University; BIDMC cardiologist Francine Welty, MD, PhD, and BIDMC Director of Radiology Research Melvin Clouse, MD.

________________________________

----- Original Message ----
From: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>
To: radsafe at radlab.nl
Sent: Thursday, May 29, 2008 9:10:12 AM
Subject: RE: [ RadSafe ] Cumulative Radiation Exposure Shows Increased CancerRisk for Emergency Department Patients

I am a HUGE fan of the idea electronic medical records, and agree that
it is reasonable to include a patients cumulative dose in those records.
HOWEVER, I believe it is contra-indicated to worry about long term risk
from radiation in a bona-fide medical emergency.  Long-term risk
decreases to zero as short-term death increases to one.

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of ROY HERREN
Sent: Wednesday, May 28, 2008 10:56 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Cumulative Radiation Exposure Shows Increased
CancerRisk for Emergency Department Patients

http://www.blackwellpublishing.com/press/pressitem.asp?ref=1740
Cumulative Radiation Exposure Shows Increased Cancer Risk for Emergency
Department Patients

________________________________

SOCIETY FOR ACADEMIC
EMERGENCY MEDICINE
UNDER EMBARGO UNTIL May 29, 2008 (12:01 AM ET)
Contact:
Sean Wagner
Wiley-Blackwell
781-388-8550
swagner at wiley.com
Cumulative Radiation Exposure Shows Increased Cancer Risk for Emergency
Department Patients According to a new study, patients are receiving
estimated doses of radiation from medical diagnostic imaging studies,
such as CT (or "CAT") scans, that may be detrimental to their long term
health, putting them at an increased risk of developing cancer. To date,
emergency physicians have not been made aware of the cumulative amount
of radiation that their patients receive. In fact they currently have no
way to know or estimate any given patient's cumulative dose. A new study
hopes to quantify and further explore these concerns.
Led by Timothy B. Bullard, M.D., M.B.A of the Orlando Regional Medical
Center (ORMC), the cross-sectional study examined the amount of ionizing
radiation that a random selection of patients received over a five-year
period at ORMC and Washington Hospital Center in Washington, D.C. The
study is the first to estimate the total cumulative radiation dosage
delivered to a population from multiple diagnostic imaging modalities
during a defined period of time. 
Patients had an average cumulative estimated effective radiation dose of
45.0 milliseiverts, with CT scans and nuclear medicine studies
contributing the most radiation. Twelve percent of the sample population
was estimated to have received 100 or more millisieverts of radiation, a
value that exceeds the accepted threshold of safety for exposure to low
level ionizing radiation. If study patients are representative of the
general emergency department population, then a substantial number of
people may be placed at increased risk of developing cancer over their
lifetime from diagnostic imaging studies as a result of these exposures.
"Our research hopefully will affect the habits of physicians who
routinely order medical imaging diagnostic studies in their practices,"
says Bullard. "We also hope that our research will further promote the
need for electronic medical records with portability and encourage the
development of an individual patient cumulative exposure estimate tool."
The presentation is entitled "Cumulative Radiation Exposure and Cancer
Risk from Diagnostic Imaging in Patients Presenting to the Emergency
Department." This paper will be presented at the 2008 SAEM Annual
Meeting in Washington, D.C. on May 29, 2008, in the moderated poster
session beginning at 3:00 p.m. in Exhibit Hall A of the Marriott Wardman
Park Hotel. Abstracts are published in Vol. 15, No. 5, Supplement 1, May
2008 of Academic Emergency Medicine, the official journal of the Society
for Academic Emergency Medicine.
# # #
Press Room - 2008 SAEM Annual Meeting, May 29-June 1, 2008,Washington,
D.C.
Location Park Tower Suite #8229
Tel: (202)-328-2000 (ask for the SAEM Registration Desk)
Fax: (202)-234-0015 2 (mark for attn of Maryanne Greketis or Sandra
Rummel) Contact Sean Wagner (swagner at wiley.com) to arrange for an
interview prior to or during the SAEM Annual Meeting. Dr. Bullard can be
reached directly at timothy.bullardmd at orhs.org.
About The Society for Academic Emergency Medicine (www.saem.org) The
Society for Academic Emergency Medicine (SAEM) is a national non-profit
organization of over 6,000 academic emergency physicians, emergency
medicine residents and medical students. SAEM's mission is to improve
patient care by advancing research and education in emergency medicine.
SAEM's vision is to promote ready access to quality emergency care for
all patients, to advance emergency medicine as an academic and clinical
discipline, and to maintain the highest professional standards as
clinicians, teachers, and researchers. The SAEM Annual Meeting attracts
approximately 2,000 medical students, residents and academic emergency
physicians. It provides the largest forum for the presentation of
original research in the specialty of Emergency Medicine. 
About Academic Emergency Medicine (www.aemj.org) AEM is a peer-reviewed
journal whose goal is to advance the science, education, and clinical
practice of emergency medicine, to serve as a voice for the academic
emergency medicine community, and to enhance the goals and objectives of
the Society for Academic Emergency Medicine (SAEM). Members and
non-members worldwide depend on this journal for translational medicine
relevant to emergency medicine, in addition to clinical news, case
studies and more.
About Wiley-Blackwell
Wiley-Blackwell was formed in February 2007 as a result of the
acquisition of Blackwell Publishing Ltd. by John Wiley & Sons, Inc., and
its merger with Wiley's Scientific, Technical, and Medical business.
Together, the companies have created a global publishing business with
deep strength in every major academic and professional field.
Wiley-Blackwell publishes approximately 1,400 scholarly peer-reviewed
journals and an extensive collection of books with global appeal. For
more information on Wiley-Blackwell, please visit
www.blackwellpublishing.com or http://interscience.wiley.com. 
Media ContactSean Wagner
Public Relations Specialist
350 Main St.

Malden, MA 02148
United States
781-388-8550 (phone)
781-338-8550 (fax)
swagner at bos.blackwellpublishing.com

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