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Archive for August, 2010

Up to now, it was therefore almost impossible to image moving organs using MRI. According to Max Planck researchers from Göttingen have now succeeded in significantly reducing the time required for recording images to a very minimal time. This invention or method makes it possible to view the pictures as and when they are taken which makes it “Live” presentation for the first time. The doctors are provided with more information than before for a better study. In many cases MRI examinations may become easier and more comfortable for patients.

FLASH brought in the break through. FLASH revolutionized MRI and was largely responsible for its establishment as a most important modality in diagnostic imaging. MRI is completely painless and, moreover, extremely safe. Because the technique works with magnetic fields and radio waves, patients are not subjected to any radiation exposure as is the case with X-rays. At present, however, the procedure is still too slow for the examination of rapidly moving organs and joints. For example, to trace the movement of the heart, the measurements must be synchronized with the electrocardiogram (ECG) while the patient holds the breath. Afterwords, the data from different heart beats have to be combined into a film.

Whilst still relying on the FLASH technique, the scientists used a radial encoding of the spatial information which renders the images insensitive to movements.

“Considerably fewer data are recorded than are usually necessary for the calculation of an image. We developed a new mathematical reconstruction technique which enables us to calculate a meaningful image from data which are, in fact, incomplete,” explains Frahm.

Although these fast MRI measurements can be easily implemented on today’s MRI devices, something of a bottleneck exists when it comes to the availability of sufficiently powerful computers for image reconstruction. Physicist Martin Uecker explains: “The computational effort required is gigantic. For example, if we examine the heart for only a minute in real time, between 2000 and 3000 images arise from a data volume of two gigabytes.” Uecker consequently designed the mathematical process in such a way that it is divided into steps that can be calculated in parallel. Therefore, it will take a while until MRI systems are equipped with computers that will enable the immediate calculation and live presentation of the images during the scan. In order to minimize the time their innovation will take to reach practical application, the Göttingen researchers are working in close cooperation with the company Siemens Healthcare.

CT Colonography or Virtual Colonoscopy can detect colonic as well as extra-colonic abdomino-pelvic lesions, an added advantage over colonoscopy.  Virtual colonoscopy uses computerized tomography (CT) to produce hundreds of cross-sectional images of the abdominal organs which are analysed tp produce a veirtual image of the inside of the colon and rectum while colonoscopy is the endoscopic examination of the colon using a colonoscope allowing direct vizualisation of the colon and rectum.

The new findings were reported in the September issue of the American Journal of Roentgenology.

Even though CT colonography (CTC) cannot be compared to CT pelvis and abdomen, the extracolonic findings detected during the procedure can be significant and provides a clear advantage over conventional optical colonoscopy Dr. Ganesh R. Veerappan, MD, of Walter Reed Army Medical Center in Washington and colleagues conducted a retrospective study to analyse the significance of these lesions.

The researchers found that out of the 2277 patients who underwent CTC, about 45 percent cases had extracolonic findings and a quarter of these findings were significant. Further radiology procedures, surgery and follow-up revealed 7 high-risk lesions among the significant lesions and the radiology studies added approximately $50 extra per patient. The virtual colonoscopy examination found six intracolonic malignancies and three adenomas with high-grade dysplasia.

“CT colonography [CTC] not only identifies colorectal cancer [CRC] but also doubles the yield of identifying significant early extracolonic lesions, resulting in lives saved,” Ganesh Veerappan reported in the journal.

The team concluded that the odds of identifying high-risk lesions were raised by 78% with CTC and thus the examination should be considered as an alternative to conventional colonoscopy in colo-ractal cancer screening or as a one-time screening procedure for intracolonic and extra-colonic lesions.

Cross checking through the patient’s total past exposure, and then carefully weighing the risks and benefits of each test and any alternative approaches that can be taken is a good approach to reduce excessive Radiation Risks.

There are two new studies appearing in the Tuesday’s issue of the journal Radiology which suggested more physicians should take this approach. It was also found in a recent study that certain nuclear-based breast imaging exams that involve injecting radioactive material into patients expose women to far higher doses of radiation than regular mammography, increasing their risk of cancer in vulnerable organs beyond the breast, like the kidneys, bladder or ovaries. Over all, the United States population’s annual radiation dose from medical procedures increased sevenfold between 1980 and 2006, a second paper reports.

A latest article published by Roni Caryn Rabin in The New York Times shows how Dr. Deborah Rhodes approaches radiation tests is a remarkable study. Before she orders for a diagnostic test that involves radiation, she consults a chart in her office that lists the amount of radiation exposure from each test. She considers the patient’s total past exposure, and then carefully weighs the risks and benefits of each test and any alternative approaches she can take. “I’m a radiation phobe — I’ll come right out and say this,” said Dr. Rhodes, an internist at the Mayo Clinic who is doing research to develop screening technologies that require less radiation exposure to the patient. “I’m constantly monitoring radiation doses in my patients.”

She also mentioned, “this is something that isn’t well understood, not just by the public — but by physicians who order the tests.” R. Edward Hendrick is a physicist who has studied breast imaging for almost 30 years, said he was motivated to quantify the radiation exposure from nuclear breast imaging technologies in a published paper because of similar concerns.

“I would go to the international breast meeting and the big radiology meetings, and nobody had a clue what the doses and risks were,” Dr. Hendrick said. “They’re treating all the tests as if they have the same radiation dose and risk as mammography, and the truth is they have a much, much higher risk. The point of the paper was to say that not all the breast imaging procedures have comparable risks and doses.”

Dr. Hendrick who is a clinical professor of radiology at the University Colorado-Denver School of Medicine in Aurora, Colo., is also a consultant to G.E. Healthcare regarding digital breast tomosynthesis, another breast imaging technique, and is on the medical advisory boards of Koning and Bracco, which make other imaging technologies. The nuclear technologies breast-specific gamma imaging (B.S.G.I.) and positron emission mammography (P.E.M.) are meant to be used as complements or adjuncts to mammography and ultrasound, once there is concern about a cancerous lesion, and not for routine screening. These technologies are also more useful in women who have very dense breast tissue, when mammography often does not provide clear images.

It is noticed that a single breast-specific gamma imaging or positron emission mammography exam exposes patients to a risk of radiation-induced cancer that is comparable to the risk from an entire lifetime of yearly mammograms starting at 40, according to Dr. Hendrick’s study. While digital mammography has an average lifetime risk of inducing 1.3 fatal breast cancers per 100,000 women aged 40 at exposure, a single B.S.G.I. exam was estimated to involve a lifetime risk 20 to 30 times greater in women aged 40, and the lifetime risk of a single P.E.M. was 23 times greater.

Moreover, mammography only increases a woman’s risk for breast cancer while B.S.G.I. and P.E.M. increase the risk of cancer in other organs, such as the intestines, kidneys, bladder, gallbladder, uterus, ovaries and colon, the recent study declared. There is also a concern that use of the imaging technologies will become more widespread and casual. “B.S.G.I. and P.E.M. are great tools for problem solving, if you have a patient with an abnormal mammogram and you’re not really sure,” said Dr. Rhodes. “The problem is these tests are now being considered and even being used in some cases as screening tests, and this is not appropriate.”

“I’m not saying ‘Don’t do the test,’ I’m just saying ‘Don’t prescribe these tests willy-nilly like you would an ultrasound exam,’ ” Dr. Hendrick said.

A few suggested proposals namely for curbing excessive use of imaging include developing national evidence-based appropriateness criteria for imaging, educating referring physicians and the public, curbing the physician practice of self-referral and finding ways to reduce duplicate exams. William R. Hendee, a distinguished professor of radiology, radiation oncology, biophysics and bioethics at the Medical College of Wisconsin in Milwaukee, called on radiologists to spearhead a campaign to reduce overuse of imaging technologies that expose patients to radiation unnecessarily and drive up health costs in the process

“The comparison to mammography is a bit like comparing apples to oranges,” said Doug Kieper, vice president of science and technology for Dilon Technologies Inc., which developed the B.S.G.I. technology. “This is not being used as a screening procedure for the general asymptomatic population who have no indication of disease.” He added that studies were already under way to see if the same results could be obtained using lower doses of radiation.

The latest training programme in ultrasound has been made compulsory for doctors undergoing specialty training in obstetrics and gynecology is now being implemented nationally.

The ultrasound training will be given by sonographers following discussions between the Royal College of Obstetricians and Gynecologists (RCOG) and the Society and College of Radiographers (SCoR).

Mr Christoph Lees, RCOG national ultrasound training co-coordinator said, “The RCOG programme provides for ‘deanery ultrasound co-coordinators’ who will normally be obstetricians-gynecologists and local ‘ultrasound education

supervisors’ who may, for example, be ultrasound department managers or lead sonographers.”

“The intention is that there are local discussions between these individuals as to how the RCOG training can be delivered, taking into account the number of potential trainees of all disciplines, the numbers already being trained within the department (including sonographer trainees), the available workforce and department capacity.”

NHS trusts and boards will be expected to implement the training as part of the core syllabus requirements. Audrey Paterson, Director of Professional Policy at the SCoR said, “The aim of the training is to improve maternal and woman’s

healthcare, especially outside of normal hours when sonographer cover may not be available. Sonographers have traditionally played a major role in the training of doctors in obstetric and gynaecological ultrasound and their involvement is not new.

“Everyone recognizes the need for an inter-professional approach to ensure the new training programme is delivered effectively.”

Researchers from Mount Sinai School of Medicine have created a method to visualize coronary artery plaques vulnerable to rupture using multi-color computed tomography (CT).

An innovative multicolor CT is a very helpful innovation that will bring in a better and earlier diagnosis of cardiovascular disease. The information are published in the September issue of Radiology.

Ruptures of atherosclerotic plaques are due to nearly 70 percent of heart attacks. High density lipoproteins (HDL), the “good” cholesterol, are drawn to plaques vulnerable to rupture and remove them from the arterial wall. The Mount Sinai team harnessed HDL by enveloping tiny gold particles within it and injected them into mice. By using a sophisticated multi-color CT scanner, the researchers were able to view the gold particles as the HDL was targeting macrophages. It also targetted cells that caused inflammation in the arterial wall, therefore highlighting the location of the vulnerable plaques.

“The use of multi-color CT and gold nanoparticles to visualize plaque will revolutionize cardiac imaging,” said the research team leader, Zahi A. Fayad, PhD, Professor of Radiology and Medicine and the Director of the Translational and Molecular Imaging Institute at Mount Sinai School of Medicine. “The acquisition of this technology and development of this method will help us improve cardiovascular disease diagnosis in our patients, furthering our commitment to translational research. We look forward to continuing our study of this technology in the clinical setting.”

Conventional CT detectors brings about a gray image of the artery being studied, and are impossible to present contrast to differentiate types and density of tissue. Additionally, spectral CT can simultaneously distinguish calcium deposits and contrast agents used such as iodine, which is often used to identify stenoses, or the narrowing of arteries, informing the severity of atherosclerosis and heart attack risk.

The first institution in the world to use this scanner, made by Phillips Medical Systems, in a pre-clinical setting is the Mount Sinai. “There is a significant unmet need for imaging technology that visualizes plaque vulnerable to rupture,” said the lead author of the work, David Cormode, PhD, Postdoctoral Fellow, Translational and Molecular Imaging Institute, Mount Sinai School of Medicine. “The fact that the multi-color CT technique shows the gold particles, iodine and calcifications, provides us with a more complete picture of the nature of the atherosclerotic arteries.”

Multi-color CT technology may also be handy in imaging other biological process and diseases, including cancer, kidney disease, and bowel diseases. The Mount Sinai team plans to continue studying the new scanner in additional animal studies and in humans.

“Mount Sinai has a decades-long history of making advances in cardiac imaging that have had a significant impact on the field and in patient care,” said Valentin Fuster, MD, PhD, Director of Mount Sinai Heart, the Zena and Michael A. Wiener Cardiovascular Institute and the Marie-Josee and Henry R. Kravis Center for Cardiovascular Health, The Mount Sinai Medical Center. “As the first center in the world to pioneer this imaging method, we are leading the charge once more in improving diagnostic tools that lessen the potentially devastating impact of heart disease.”

U.S. researchers have declared that Magnetic Resonance Imaging (MRI) could help assess prostate cancers that need more aggressive treatment.

Researchers at Rutgers University in New Brunswick, N.J., report more than 90 percent accuracy in distinguishing low-grade from high-grade prostate cancers using magnetic resonance spectroscopy that maps concentrations of certain chemicals that indicate the presence of cancer in the prostate gland.

“The breakthrough we’ve had in the last few months is that we see image signatures that distinguish aggressive cancers from less aggressive ones,” Anant Madabhushi says in a statement. “Now we’re getting beyond merely identifying whether a person has cancer or not.”

In a initial case study, Madabhushi and colleagues used computer analysis of the images and spectra to differentiate prostate tumors on 19 patients who later had the prostate surgically removed.

“Recent studies suggest men with low-risk cancers receive aggressive treatment, but improved diagnostic methods outlined by this study may help patients with low-risk cancers and their physicians feel more confident with watchful waiting”, Madabhushi says.

The Rutgers findings are scheduled to be presented at the Medical Image Computing and Computer Assisted Intervention Conference held in Beijing in September.

For patients with brain tumors who don’t have a variety of option have to settle with a surgery and radiation which can damage crucial parts of the brain. It is also seen that the chemotherapy drugs don’t easily percolate through the blood-brain barrier.

An effective solution is being launched where a procedure using magnets, ultrasound and minuscule drug-coated particles may be an effective solution, published in Tuesday’s edition of the journal Proceedings of the National Academy of Sciences.

The researchers, led by Dr. Kuo-Chen Wei of Chang Gung University in Taiwan, injected tiny magnetic beads called nanoparticles, coated with a chemotherapy drug, into the rats’ tails. Ultrasound was used to open up a small region of
the blood-brain barrier and a magnetic field to attract the particles to an actual location in the brain. This procedure of treating rats with brain tumors resulted in slowing the tumor growth in rats lived two-thirds longer than untreated rats.

“The technology’s not very difficult,” Wei said, “but the idea is novel.”He also added that clinical trials in human beings are at least four to five years away.

It becomes difficult to treat brain tumors to treat with traditional drug delivery methods because the brain is insulated from circulating blood. The focused ultrasound which is much stronger than the ultrasound technique used on pregnant women temporarily disrupts the barrier and also allows drugs to enter.

Once the drugs get into the brain, It should be properly allotted to the actual places to cut down on the damage to healthy tissue. This report is the first in which magnetic targeting was combined with ultrasound to attract the nanoparticles and their drug passengers to a specific part of the brain.

“The method has significant clinical potential,” said Dr. Kullervo Hynynen of the University of Toronto Medical School, who conducts similar research but was not involved in the new study.

Wei and his team are working to improve the treatment so that it can be also used on humans. He declared that first additional chemotherapy drugs and nanoparticle types had to be tried, as well as improve the ultrasound and magnetic-targeting technology. Some scientists still are under the impression that opening the blood-brain barrier to allow powerful chemicals into the brain is too dangerous on humans.

“The potential for toxicity in normal brain regions could cause all kinds of problems,” said Allan David, a drug delivery researcher at the University of Michigan. “I think it’s an interesting study, but it’s still far from clinical studies.”

Some amount of danger in opening the blood-brain barrier can be avoided by combining Wei’s approach with a type of drug that is activated only upon reaching the tumor, David said, so that healthy brain tissue is left unharmed.

For the safety of the pediatric cardiovascular and vascular patients wh o need the CTA for diagnostic purposes, low dose CTA is essential, says Jeffrey C. Hellinger, M.D., a pediatric imaging specialist at Stony Brook University Medical Center. Dr. Hellinger has also shared his views on the topic in the early online edition of Radiologic Clinics of North America.

Dr. Hellinger has developed CTA protocols and new measures that he has spoken about has balanced lower doses of radiation and clear diagnostic images when using CTA on infants and children. As Principal Author of “Pediatric  Computed Tomographic Angiography: Imaging the Cardiovascular System Gently,” Dr. Hellinger details the appropriate and safe use of non-invasive CTA, in the context of other potential cardiovascular imaging modalities, including radiography, echocardiography, vascular ultrasound, magnetic resonance imaging (MRI) and angiography (MRA), and invasive catheter angiography (CA).

“The use of any radiation in diagnostic methods carries a risk of causing cancer and of abnormal development, particularly in infants and children,” says Dr. Hellinger. “There is basically a medical necessity, if you are going to use  radiation in your imaging, to use the lowest possible amount,” he emphasizes.

“I think it’s a controversial topic as to how much radiation will lead to increased cancer risk over the lifetime of a patient,” he adds. “As physicians and imagers, with CT angiography, it is our goal to use the lowest possible radiation without compromising imaging quality. There a balance between how low you can go with the technology and rendering a diagnosis. If the radiation dose is too low and the image is poor, you have wasted the radiation.”

Dr. Hellinger and co-authors present their findings on low-dose pediatric CTA protocols and the needed ancillary protocols to achieve high image quality, emphasizing that using complementary “gentle” cardiovascular CT “can  enhance the diagnosis and management of the pediatric patient with cardiovascular disease. Given the intrinsic dependencies upon radiation, utilizing this modality in pediatric patients mandates a commitment to dose reduction strategies, striving for ALARA (As Lows As Reasonably Achievable) in each cardiovascular CT examination.”

For each patient, Dr. Hellinger writes, all the sectors surrounding cardiovascular CT should be reviewed. “The pediatric CTA protocols are uniquely designed to maximize the table speed, image at the lowest possible voltage, and use the  lowest possible weight-based tube current.”

Dr. Hellinger, who joined SBUMC around the June 2010 launch of Stony Brook Long Island Children’s Hospital, the only dedicated children’s hospital east of the Nassau/Queens border, developed an expertise in creating low dose radiation pediatric imaging protocols over the past four years. He built a cardiovascular imaging program in the Department of Radiology at The Children’s Hospital of Philadelphia (CHOP).

At SBUMC, Dr. Hellinger partners with Michael Poon, M.D, Director of the Advanced Cardiac Imaging Program and a world-renowned expert in cardiac CT and MRI. Central to their imaging diagnostic methods is SBUMC’s acquisition  earlier this year of a state-of-the art 320-detector row CT scanner, which provides physicians with accurate images of internal organs with a single rotation of the gantry, that results in lower doses of radiation while providing the best  imaging features possible.

Researchers at the Mayo clinic are researching on how to reduce the radiation dose during CT (Computed Tomography) perfusion studies, which is being popular as the diagnostic test for cerebrovascular accidents (stroke).

The researchers presented their findings at the 52nd Annual Meeting of the American Association of Physicists in Medicine on July 20 in Philadelphia. The presentation was titled “20-Fold Dose Reduction Using a Gradient Adaptive Bilateral Filter: Demonstration Using in Vivo Animal Perfusion CT.”

Dr. McCollough, diagnostic radiologist and colleagues at the  Mayo Clinic created a novel image-processing algorithm and experimented in animals and proved that it can produce high quality perfusion images at around 20 times less radiation exposure to the patient when compared to normal CT perfusion protocols. A CT perfusion scan takes arond 30 seconds after radio-iodine contrast injection revealing the areas of decreased vascular perfusion. The different images are superimposed for better quality and accurate diagnosis.

After the success in animals, Dr. McCollough and team plans to try the new technique in humans.

“When we use very low doses of radiation to acquire a CT, image graininess can significantly decrease the value of the exam,” says the study’s first author, Juan Carlos Ramirez Giraldo, Mayo Clinic. “With this new algorithm, we are able to maintain the image quality by cross-referencing it with other images collected during the exam.”

Ultrasound is the standard investigation done in the diagnosis and follow-up of urinary calculi. But researchers at the department of urology, St. Michael’s Hospital, University of Toronto suggest that ultrasound may not be the most reliable investigation in the management of renal stones.

According to them, the two promimant disadvantages of ultrasound when compared to computed tomography in renal stones management are:

1. Overestimation of stone size: When compared with axial unenhanced CT, ultrasound shows the size to be bigger than the actual size which can lead to unnecessary surgical interventions in cases where only conservative management is warranted. Thus the authors advise against for planning treatment based solely on ultrasonography (US) findings. The study also found that the skin-stone distance, ie the distance between the ultrasound probe over the skin and the position of the calculi, is a significant factor determining the magnitute of the error. The error was not dependent on the body mass index and location of the calculi in the urinary tract.

2. Poor sensitivity and specificity for kidney and ureter stones: The team found that the sensitivity and specificity of US for the detection of ureteric calculi was 45% and 94%, respectively, and for the detection of renal calculi was 45% and 88%, respectively. Thus they consider US as not that worthy during an initial workup in the diagnosis of renal stones.

The authors found that CT is superior to ultrasound and US may be limited to:

• pregnant and pediatric patients where exposure to radiation is harmful.
• follow-up of translucent urinary calculi.
• in cases of hydronephrosis
• when there is need for repeated CT