Cardiac Imaging
Researchers at the UT Southwestern Medical Center have discovered that magnetic resonance imaging (MRI) of aortic atherosclerosis can foresee the risk of heart attacks and other cardiovascular issues in healthy people.
The study, which was published in the June issue of Radiology, is the first of its kind in assessing the extrapolative significance of MRI measures of aortic atherosclerosis for possible cardiac episodes.
"This is an important study, because it demonstrates that atherosclerosis in an artery outside the heart is an independent predictor of adverse cardiovascular events. MRI is a promising tool for quantifying atherosclerosis through plaque and arterial wall thickness measurements,” said radiology resident at the University of Texas Southwestern Medical Center in Dallas and lead author, Christopher D. Maroules, M.D.
Atherosclerosis is a condition in which fat, cholesterol and other substances gather within the arteries, forming plaque. As plaque amasses, the artery narrows, obstructing blood flow. The condition can take place in any artery, including the cerebral (brain) and coronary (heart) arteries and the aorta, which delivers oxygenated blood from the heart through the abdomen to the rest of body. The aorta is the largest artery body.
Over 2,200 healthy adults (average age 44) from the Dallas Heart Study, a pioneering multiethnic examination of cardiovascular disease in Dallas County residents, were subjected to abdominal aortic MRI as part of the research study.
Two key findings from the study were the average abdominal aortic wall thickness, or the thickness of the vessel wall, and the volume of plaque buildup.
After the MRI, participants were observed for a time-period of 7.8 years. Throughout that period, 143 participants had an unfavorable cardiac episode where arterial blood flow was limited, leading to death or medical attention. Researchers grouped the events as associated to the heart (cardiac events) or to other arteries (called extra-cardiac vascular events) like those in the brain or abdomen.
From the 143 cardiovascular episodes, 34 resulted in death. Seventy-three were non-fatal cardiac events, which included heart attack or coronary revascularization, and 46 were non-fatal extra-cardiac vascular events, including stroke or carotid revascularization.
By using MRIs, the study discovered that a rise in abdominal wall thickness is connected to a great chance for all kinds of cardiovascular episodes. A rise in both wall thickness and aortic plaque was linked to a risk for non-fatal extra-cardiac vascular events.
"These MRI measurements may add additional prognostic value to traditional cardiac risk stratification models," said Maroules.
Through MRIs, the abdominal aorta poses less of a practical challenge compared to other vascular imaging methods, due to the great size of the vessel and its independence of being around any mobile organ, such as the heart or lungs. Additionally, images of the abdominal aorta can be attained even if patients undergo different procedures, such as MRI of the spine or abdomen.
"The abdominal aorta is incidentally imaged on a regular basis. Radiologists can infer prognostic information from routine MRI exams that may benefit patients by identifying subclinical disease,” said Maroules.
For now Maroules believes further MRI studies will produce a greater understanding of the development of atherosclerosis, which scientists assume begins with a reconstruction or thickening of the vessel wall before any buildup of plaque can
... Read more
Cardiac Imaging News
MRI Used to Predict Heart Attack, Stroke Risk Increases with …
Researchers at the UT Southwestern Medical Center have discovered that magnetic resonance imaging (MRI) of aortic atherosclerosis can foresee the risk of heart attacks and other cardiovascular issues in healthy people.
The study, which was published in the June issue of Radiology, is the first of its kind in assessing the extrapolative significance of MRI measures of aortic atherosclerosis for possible cardiac episodes.
"This is an important study, because it demonstrates that atherosclerosis in an artery outside the heart is an independent predictor of adverse cardiovascular events. MRI is a promising tool for quantifying atherosclerosis through plaque and arterial wall thickness measurements,” said radiology resident at the University of Texas Southwestern Medical Center in Dallas and lead author, Christopher D. Maroules, M.D.
Atherosclerosis is a condition in which fat, cholesterol and other substances gather within the arteries, forming plaque. As plaque amasses, the artery narrows, obstructing blood flow. The condition can take place in any artery, including the cerebral (brain) and coronary (heart) arteries and the aorta, which delivers oxygenated blood from the heart through the abdomen to the rest of body. The aorta is the largest artery body.
Over 2,200 healthy adults (average age 44) from the Dallas Heart Study, a pioneering multiethnic examination of cardiovascular disease in Dallas County residents, were subjected to abdominal aortic MRI as part of the research study.
Two key findings from the study were the average abdominal aortic wall thickness, or the thickness of the vessel wall, and the volume of plaque buildup.
After the MRI, participants were observed for a time-period of 7.8 years. Throughout that period, 143 participants had an unfavorable cardiac episode where arterial blood flow was limited, leading to death or medical attention. Researchers grouped the events as associated to the heart (cardiac events) or to other arteries (called extra-cardiac vascular events) like those in the brain or abdomen.
From the 143 cardiovascular episodes, 34 resulted in death. Seventy-three were non-fatal cardiac events, which included heart attack or coronary revascularization, and 46 were non-fatal extra-cardiac vascular events, including stroke or carotid revascularization.
By using MRIs, the study discovered that a rise in abdominal wall thickness is connected to a great chance for all kinds of cardiovascular episodes. A rise in both wall thickness and aortic plaque was linked to a risk for non-fatal extra-cardiac vascular events.
"These MRI measurements may add additional prognostic value to traditional cardiac risk stratification models," said Maroules.
Through MRIs, the abdominal aorta poses less of a practical challenge compared to other vascular imaging methods, due to the great size of the vessel and its independence of being around any mobile organ, such as the heart or lungs. Additionally, images of the abdominal aorta can be attained even if patients undergo different procedures, such as MRI of the spine or abdomen.
"The abdominal aorta is incidentally imaged on a regular basis. Radiologists can infer prognostic information from routine MRI exams that may benefit patients by identifying subclinical disease,” said Maroules.
For now Maroules believes further MRI studies will produce a greater understanding of the development of atherosclerosis, which scientists assume begins with a reconstruction or thickening of the vessel wall before any buildup of plaque can
... Read more
New Algorithm Measures Heart Rate by Head Movements…
A newly developed algorithm has the ability to measure heart rates of individuals displayed on a digital video-platform by observing indiscernible head movements that come with a rush of blood due to the heart’s activity.
Researchers from the Massachusetts Institute of Technology (MIT) Computer Science and Artificial Intelligence Laboratory Department constructed the algorithm that issued pulse estimations that kept pace within a few beats per minute of those released by electrocardiograms (EKGs).
Furthermore, the algorithm was shown to be able to deliver a rough calculation of the time gaps between beats, a method used to identify patients who may be at cardiac risk.The team of researches is set to reveal their findings this summer at the Institute of Electrical and Electronics Engineers' Computer Vision and Pattern Recognition conference.
This new digital video-platform, pulse-calculating algorithm could be utilized in time to check the heart rates of senior citizens or newborns, without running the risk of repeatedly using EKG leads that may irritate or harm sensitive skin.
"From a medical perspective, I think that the long-term utility is going to be in applications beyond just pulse measurement. Can you use the same type of techniques to look for bilateral asymmetries? What would it mean if you had more motion on one side than the other?" said Dugald C. Jackson Professor of Electrical Engineering and Computer Science and director of MIT's Data-Driven Medicine Group, John Guttag.
The algorithm is a blend of different techniques known to the field of computer vision. It begins by using basic face recognition to distinguish between a patient’s head from the rest of the image. Then it arbitrarily selects 500 to 1,000 precise points, cluttered around the patient’s nose and mouth, following every movement frame by frame.
From there, it sifts out any frame by frame movements that lose its overall frequency/detection levels outside the range of a standard heart beat, about 0.5 to 5 hertz, or 30 to 300 cycles per minute. This will discard any movements that persist at a lower frequency, such as those caused by normal breathing and slow changes in stance.
Finally, using a technique known as principal component analysis, the algorithm breaks down the resulting signal into numerous component signals, which stand as part of the remaining movements that have no association with one another. From those signals, it selects one that seems to be the most regular and that drops within the usual frequency band of the human pulse.
Guttag went on to state that theoretically, the system could determine cardiac output, or the quantity of blood pumped by the heart, which is often a means of diagnosis in most cardiac cases.
“Before the echocardiogram, cardio output was measured by calculating exactly the types of mechanical forces that the new algorithm registers. I think this should be viewed as proof of concept. It opens up a lot of potential flexibility,” he
... Read more
New Research Validates Worth of PET/MR Compared to …
Researchers at the Society of Nuclear Medicine and Molecular Imaging's 2013 Annual Meeting say that only a few years ago, an implementation positron emission tomography and magnetic resonance (PET/MR) imaging was available on in research-based institutions; yet have now found a place in current medical practice.
This is particularly true for cardiac indications, for which the highly receptive soft tissue contrast of MR and the practical and metabolic imaging of PET are especially precious. New research validates the worth of PET/MR compared to PET/computed tomography (CT) in cardiac applications.PET/MR imaging methods have progressed over the past several years, primarily in terms of disease identification and the adjustment of blurring (attenuation). PET/CT systems use CT to balance attenuation, and PET/MR utilizes MR.
Therefore, a portion of the study dedicated itself to pitting the two systems against one another.
"Our research demonstrated that cardiac PET assessment for heart muscle viability using PET/MR yielded comparable results to PET acquired using PET/CT. It showed that MR can be used for PET attenuation correction in the same way that CT can,” said principal author from the Washington University in St. Louis, Mo, Jeffrey M.C. Lau, MD, PhD.
This cracked the door open for technologies in a semblance of various cardiac applications. Researchers used an imaging agent called F-18 fluorodeoxyglucose (F-18 FDG), which imitates glucose as a resource of energy for the heart and other cells that metabolize the agent voluntarily. F-18 FDG-PET scans tell cardiologists about the metabolic activity of cardiac tissues and overall heart muscle function.
The study examined FDG in cardiac cells by PET/MR contrasted with PET/CT, offering similar results. PET/MR forward toward essential clinical applications, including the use of PET/MR for imaging scarring of heart tissue and consequent impediments after cardiac arrest, with some significant advantages for patients.
"Our research provides the groundwork for future research in cardiac PET/MR imaging. PET/MR provides powerful cardiac imaging and requires a lower radiation dose than PET/CT. Also, the MRI component, which can be acquired simultaneously, provides excellent heart muscle signal for imaging scar tissue caused by heart attacks. In particular, our group is most interested in applying the PET/MR technology to evaluate the likelihood of arrhythmia or irregular heart beat development in patients who have had heart attacks,” commented Lau.
The study involved 31 patients with no history of heart complications, all undergoing both PET/CT and PET/MR with F-18 FDG injection given about an hour before PET/CT and two hours before PET/MR. Attenuation was minimized using a specialized dual-echo MR sequence that orders radiofrequency magnetic fields interrelate with atomic nuclei in the body to "see" differentiation between water and fat.
The intake of FDG in the myocardium, or heart muscle wall, was calculated by looking at a cross-section of the left ventricle of the heart that releases oxygen-rich blood into the aorta. The median measurement of FDG intake in the left ventricle was nearly indistinguishable, 4.68 for PET/MR and 4.62 for PET/CT.
Studies have shown that implanted cardiac defibrillators (ICD) are linked to the progression of ventricular arrhythmias in up to a third of implanted patients within three years. Researchers hope to collect more information about this correlation with future PET/MR
... Read more
SNMMI: Exercise FDG-PET Outdoes Stress MPI in …
In a recent study, presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) annual meeting, it was found that Exercise FDG-PET considerably outdid SPECT myocardial perfusion imaging (MPI) in identifying ischemia in patients with single-vessel disease.
For patients with stenosis higher than 50%, exercise FDG-PET pulled out an impressive sensitivity rating at 96%; as opposed to 56% for stress technetium-99m (Tc-99m) tetrofosmin SPECT MPI. FDG-PET also demonstrated a 76% precision rate in this sitting, whereas the stress MPI only attained a precision rate of 62%.
In addition, for patients with stenosis higher than 70%, the team found that both procedures were evenly matched.
“The findings could lead to the use of nuclear medicine in preventive cardiology, given FDG-PET's apparent ability to detect ischemia at a very early stage before changes become apparent with angiography,” said lead researcher from the department of nuclear medicine at the Post Graduate Institute of Medical Education and Research (PGIMER) in Chandigarh, India, Dr. Arun Sasikumar.
For the promising study, 45 patients with clinical suspicion of coronary artery disease and no history of myocardial infarction were enrolled.
Of the 45 patients, 37 were men, while the remaining eight were women, with an average age of 51 and a total age range from 27 to 71 years.
Every patient was subjected to a stress SPECT MPI using a treadmill in one day. Exercise FDG-PET was administered after inserting 5 mCi of FDG on a different day.
The researchers contained physiologic myocardial FDG intake in patients by having them eat a high-fat, high-protein, low-carbohydrate meal preceding FDG-PET. Each patient was also subjected to a coronary angiography within 30 days of the other scans to offer a basis for evaluation between SPECT MPI and FDG-PET results.
Twenty-seven patients had irregular coronary angiography that displayed at least one coronary artery with stenosis higher than 50%. Of the 27 patients, 17 had single-vessel disease, five had double-vessel disease, and five had triple-vessel disease.
For the 17 patients with single-vessel disease, FDG-PET notably outdid SPECT MPI (p = 0.0005). For patients who had stenosis higher than 50%, exercise FDG-PET had sensitivity of 96%, whereas stress SPECT MPI had 56%. Accuracy was 76% for FDG-PET, as opposed to SPECT MPI with 62%, proving that FDG-PET detects earlier stages of disease, according to the study.
For patients with multivessel disease, exercise FDG-PET did just as well as stress SPECT MPI (for double-vessel disease, p = 0.683; for triple-vessel disease, p = 1.0).
Additionally, exercise FDG-PET was also much better than stress SPECT MPI in the left anterior descending and left circumflex arteries with equally fine performance in the right coronary artery. In patients with stenosis higher than 70%, both procedures were evenly matched (p = 0.61).
“Given exercise FDG-PET's prowess, physicians could prescribe medications that can halt disease progression and prevent a potentially devastating cardiac event, such as a heart attack or sudden cardiac death,” Sasikumar and colleagues concluded.
Exercise FDG-PET could also be useful for preliminary coronary artery disease screening to assist physicians in assessing a patient’s cardiac risk and manage
... Read more
Cardiac MRI Use Lessens Unpleasant Events for Patients …
Wake Forest Baptist Medical Center doctors have discovered that using stress cardiac magnetic resonance (CMR) imaging in an Emergency Department observation unit to care and treat patients with severe chest pain is beneficial for both the patient and the institution. The study appears online in the journal, JACC: Cardiovascular Imaging.
On a small-scale clinical trial, M.D., M.S., Chadwick Miller, who also serves as director of clinical research and executive vice-chair of Emergency Medicine at Wake Forest Baptist, and his team discovered that examining older, more intricate patients in the observation sector with stress cardiac MRI, instead of the usual inpatient care, significantly trimmed down hospital readmissions, coronary revascularization procedures, and the need for additional cardiac testing.
The observation area is an annex of the Emergency Department, purposefully constructed for short stays, longer than a usual ED trip, yet shorter than a hospital admission says Miller. Cardiac MRI is a kind of heart testing that utilizes magnetic forces to capture images of the heart.
"We were looking at the optimum way to evaluate people with chest pain and focusing on those patients who are generally older, have many risk factors for coronary disease or may have had prior health problems, basically the intermediate to higher risk population,” said Miller.
"At most hospitals in the United States, after evaluation in the emergency department, these patients are admitted to the hospital to complete their care,” he added.
Funded by the National Institutes of Health's National Heart, Lung, and Blood Institute, Miller cites that the study was originally predicated on previous works in which more complex patients treated in an observation sector with stress CMR testing resulted a decrease in care costs of around $2,100 for every patient per year. For this new endeavor, researchers wanted to purposely examine and evaluate three care events: coronary revascularization, hospital readmissions and additional heart testing.
Researchers enrolled 105 patients into their study, putting them in random orders to be given treatment either in the observation area with CMR or in the hospital. After a 90 day follow up, researchers discovered major deductions in coronary revascularization procedures, fewer hospital readmissions and fewer recurrent cardiac testing episodes or the need for additional testing.
"What's exciting about this is not only can we reduce events that are important to patients, but we can reduce costs as well," Miller said. "What we think is happening is that the cardiac MRI is more accurately selecting patients who will benefit the most from having invasive procedures done. It's a win-win."
However, the initial small-scale the study was based on doesn’t serve its overall purpose in Miller’s view. Therefore he suggests these discoveries need to be shared and reproduced across a multitude of centers in order to rightfully confirm the
... Read more
Intermountain Tool Tracks Cumulative Patient Radiation…
Intermountain Healthcare is launching a system that will allow it to measure and report patients' cumulative radiation exposure from image examinations.
Hospital officials, according to a recent article in the Wall Street Journal, said they hope
... Read more
Implanted Cardiac Devices Could Be Subject to Tampering…
Sensors made to pick up a heart's rhythm in implanted cardiac defibrillators and pacemakers could be subject to tampering, according to research from the University of Michigan.
An announcement from Michigan highlights experiments in simulated
... Read more
Advances in Bedside Echocardiography…
Echocardiography is one of the most important, convenient, informative, and readily available cardiac imaging techniques. The cardiac imaging with ultrasound waves was introduced to the clinical practise in the early fifties of the last century. The
... Read more
Multi-Detector CT Coronary Angiography…
Invasive coronary angiography via cardiac catheterisation has been the gold standard in assessment of the coronary tree in patients with chest pain and ischemic heart diseases for more than half a century now. It has been used to assess the site and
... Read more
Telehealth for Cardiovascular Disease Patients Cuts …
Synchronous telehealth for cardiovascular disease patients helps to reduce costs, admission rates and length of stay, according to a study published this week in the Journal of the Medical Internet Research.
The study took place at the Telehealth
... Read more
CPOE Alerts Help to Reduce Unnecessary CT Scans…
Computerized physician order entry with decision-support alerts can help to curb unnecessary CT scans, according to new research published this week in JAMA Internal Medicine.
According to the study, conducted at Brigham and Women's Hospital in
... Read more
New Software is All Heart
…
A new software-based prototype to help doctors identify the extent of heart disease in patients without recourse to invasive procedures is to be tested on 100 patients during a three-year trial.
The prototype, which has been developed by researchers and doctors at Sheffield Teaching Hospitals NHS Foundation Trust and the University of Sheffield, works by creating a 3D model of the coronary arteries during an angiogram, giving doctors a more detailed picture of which arteries need treating.
If the trial is successful, the software offers a method of assessing heart disease that is cheaper, less time-consuming and easier to use than current methods.
Doctors use angiograms to view lesions on a patient’s artery, but to make a decision about whether to insert a stent in the artery, they also need information about whether the lesions impair blood flow, leading to angina.
Traditionally, doctors have used additional functional tests, such as nuclear scans or perfusion MRI scans, to obtain this information.
Even with additional scans, making a decision about whether to insert a stent is to some degree subjective, said Paul Morris, British Heart Foundation clinical training research fellow and project team member.
“A lot of lesions are in the moderate range, where you’re not quite sure whether to leave the lesion alone or put a stent in.”
More recently, said Morris, doctors have been able to obtain the information about flow during the angiogram itself, by inserting pressure wires inside the artery.
“If you have a bit of disease or a narrowing in the artery, the pressure drops as you cross that lesion – you have a higher pressure upstream, and a lower pressure downstream.
“Knowing that pressure information helps doctors make much more objective decisions about when to put stents in. There’s a very defined cut-off, a pressure drop, that indicates that the lesion probably could cause angina so you should probably stent it.
”The problem said Morris, is that “to put a pressure wire down an artery prolongs the procedure, costs more money, and is technically more challenging. Not as many doctors can do it, so only certain centres perform this test.”
The prototype addresses that problem by measuring the pressure without a pressure wire.
The pictures created during the angiogram are used to make a model of the artery on the computer, and an engineering process called computational fluid dynamics (CFD) is used to compute the pressures down the artery.
A pilot on 35 patients has already been carried out, in which the results from the prototype were compared with results using a pressure wire. The prototype recommended the right treatment decision in 97% of cases.
The three-year trial, funded by the Wellcome Trust, the Department of Health and the British Heart Foundation, will look at 100 patients with complicated heart disease.
If it is successful, Morris said the software could become a “highly desirable tool for cardiologists across the world”, replacing the use of functional scans and pressure
... Read more
SonoSite AxioTrack Needle Guidance Technology Now …
SonoSite, or these days FUJIFILM SonoSite, has launched its AxoTrack needle guidance technology on the SonoSite M-Turbo line of ultrasounds. Developed by Soma Access Systems out of Greenville, South Carolina, the newly FDA approved AxoTrack technology allows for needle placement directly into a vessel deep within the body.
In addition to ultrasound localization within tissue, AxoTrack uses magnets to spot the location of the needle, allowing for confident placement and faster procedures.
From the product page:
The AxoTrack™ Technology is composed of two components: a specialized transducer and a sterile procedure kit.
Together, they help to enhance your confidence and control during ultrasound-guided interventional procedures. The magnet in the needle interacts with sensors in the transducer to let you plot and reach your target easily while observing the needle’s progress in real time from start to finish.
Once your target is reached, engage the specially designed needle clamp to secure your needle tip in place during critical moments.
AxoTrack I Sterile Procedure Kit specifications:
Top Shield with Needle Clamp
Bottom Shield with Needle Guide and Protective Cap
Needle Assembly with Integral Ring Magnet
Sterile Cable Sleeve (80 cm length)
Elastic Bands
... Read more
Page 4 of 15
