Real time 3D ultrasound imaging

No one would deny that having regular check-ups is essential for your health and if you are going to overgo a full examination it is always better to address prfessionals in diagnostic and imaging services. Mnap outpatient radiology diagnostic imaging center is a unique opportunity to be sure that you will get the highest standard of medical care.

If your location is Philadelphia - MNAP can be considered the only opportunity to get outpatient radioloy services of that kind in the whole area as it possesses the highest technology equippment, like Magnetom Avanto and Siemens Magnetom Concerto. Overall the atmosphere in this diagnostic center is friedndly and the specialists are trained in many related radiology medicine areas. Custom approach to all the clients is the biggest advantage over other medical establishments of that kind in Pennsylvania.

Russian magazine “Zdorovie” states that open MRI was especially designed for those patients for who traditional mri machines seem unbearable and they feel rather claustrophobic in them.

MNAP is also called a fullscope women’s diagnostic center as, for instance, mammography services are of the highest level possible with Siemens Mammomat 3000 system.

In 2004 MNAP opened a special center that uses Sandman Sleepware System. Sleep disorders pulmonology center started research in the sphere of sleep apnea, insomnia, restless limb movements and narcolepsy.

A version of a gene previously linked to impulsive violence appears to weaken brain circuits that regulate impulses, emotional memory and thinking in humans, researchers at the National Institutes of Health’s (NIH) National Institute of Mental Health (NIMH) have found. Brain scans revealed that people with this version — especially males — tended to have relatively smaller emotion-related brain structures, a hyperactive alarm center and under-active impulse control circuitry. The study identifies neural mechanisms by which this gene likely contributes to risk for violent and impulsive behavior through effects on the developing brain.

NIMH intramural researchers Andreas Meyer-Lindenberg, M.D., Ph.D., Daniel Weinberger, M.D., and colleagues report on their magnetic resonance imaging (MRI) study online in the Proceedings of the National Academy of Sciences during the week of March 20, 2006.

“These new findings illustrate the breathtaking power of ‘imaging genomics’ to study the brain’s workings in a way that helps us to understand the circuitry underlying diversity in human temperament,” said NIH Director Elias A. Zerhouni, M.D., who conducted MRI studies earlier in his career.

“By itself, this gene is likely to contribute only a small amount of risk in interaction with other genetic and psychosocial influences; it won’t make people violent,” explained Meyer-Lindenberg. “But by studying its effects in a large sample of normal people, we were able to see how this gene variant biases the brain toward impulsive, aggressive behavior.”

The gene is one of two common versions that code for the enzyme monoamine oxydase-A (MAO-A), which breaks down key mood-regulating chemical messengers, most notably serotonin. The previously identified violence-related, or L, version, contains a different number of repeating sequences in its genetic code than the other version (H), likely resulting in lower enzyme activity and hence higher levels of serotonin. These, in turn, influence how the brain gets wired during development. The variations may have more impact on males because they have only one copy of this X-chromosomal gene, while females have two copies, one of which will be of the H variant in most cases.

Several previous studies had linked increased serotonin during development with violence and the L version of MAO-A. For example, a 2002 study* by NIMH-funded researchers discovered that the gene’s effects depend on interactions with environmental hard knocks: men with L were more prone to impulsive violence, but only if they were abused as children. Meyer-Lindenberg and colleagues set out to discover how this works at the level of brain circuitry.

Using structural MRI in 97 subjects, they found that those with L showed reductions in gray matter (neurons and their connections) of about 8 percent in brain structures of a mood-regulating circuit (cingulate cortex, amygdala) among other areas. Volume of an area important for motivation and impulse regulation (orbital frontal cortex) was increased by 14 percent in men only. Although the reasons are unknown, this could reflect deficient pruning — the withering of unused neuronal connections as the brain matures and becomes more efficient, speculates Meyer-Lindenberg.

The researchers then looked at effects on brain activity using functional MRI (fMRI) scans. While performing a task matching emotionally evocative pictures — angry and fearful faces — subjects with L showed higher activity in the fear hub (amygdala). At the same time, decreased activity was observed in higher brain areas that regulate the fear hub (cingulate, orbital frontal, and insular cortices) — essentially the same circuit that was changed in volume.

While these changes were found in both men and women, two other experiments revealed gene-related changes in men only. In a task which required remembering emotionally negative information, men, but not women, with L had increased reactivity in the fear (amygdala) and memory (hippocampus) hubs. Men with L were also deficient during a task requiring them to inhibit a simple motor response; they failed to activate a part of the brain (cingulate cortex) important for inhibiting such behavioral impulses. This region was, conspicuously, the cortex area that was most reduced in volume.

The findings echo those of a 2005 NIMH study** showing how another serotonin-related gene variant shapes the same mood-regulating circuit. In this study also, the gene version that boosts serotonin levels resulted in impaired emotion-related lower brain structures, increased fear hub activation and a weaker response of its regulatory circuits. Yet, the effects of the L version of MAO-A were more extensive, perhaps reflecting the fact that it also impacts another key mood-regulating neurotransmitter, norepinephrine.

The weakened regulatory circuits in men with L are compounded by intrinsically weaker connections between the orbital frontal cortex and amygdala in all men, say the researchers.

“Heightened sensitivity in brain circuits important to cognitive inhibition and memory for negative emotional information may contribute to increased vulnerability of men with L exposed to abuse during childhood,” suggested Weinberger. “Since only men showed gene effects in several of these circuits, this could lead to a situation where multiple brain control mechanisms are impaired and contribute to manifestly violent behavior, a kind of genetic double jeopardy.”

Also participating in the study were: Joshua Buckholtz, Bhaskar Kolachana, Ahmad Hariri, Lukas Pezawas, Giuseppe Blasi, Ashley Wabnitz, Robyn Honea, Beth Verchinski, Joseph Callicott, Michael Egan, and Venkata Mattay, NIMH Clinical Brain Disorders Branch.

Read the rest of this entry »

Acoustic Radiation Force Impulse (ARFI) imaging exploits differences in the mechanical properties of soft tissue to delineate tissue structure that is not necessarily apparent with conventional B-Mode ultrasound. In ARFI imaging, an impulse of relative high acoustic energy is transmitted into the body to deliver spatially and temporally localized radiation force at the imaging focus in a manner that subtly pushes tissue away from the imaging transducer (tissue displacement is on the order of microns). Each ARFI impulse is followed by ensembles of conventional ultrasonic transmit-receive lines, which serve to generate data for ARFI-induced axial motion tracking with one-dimensional cross-correlation. Displacements measured in space and time may then be rendered into graphical and parametric image representations that depict differences in tissue mechanical properties. Given that ARFI imaging is implemented using a conventional diagnostic ultrasound system (specially equipped for research purposes) and conventional ultrasound transducers, virtually simultaneous matched B-Mode and Doppler imaging is possible. The physical basis of ARFI imaging is presented with extensive detail by Nightingale et al. (Nightingale, 2003). In comparison to alternative approaches to noninvasive screening for CVD, such as MR or X-ray based imaging methods, ARFI imaging is advantageous in that is fundamentally an ultrasonic imaging technology. Therefore, it is non-ionizing, relatively inexpensive, real-time, and portable. In addition, matched B-Mode and Doppler ultrasonography is readily realizable.

A matched B-mode image of the left iliac artery of a 1 year 8 month-old familial hypercholesterolemic pig  is presented in (a), with a focal atherosclerotic plaque (red arrow, ‘AP’) and hyper-echogenicity of the leading plaque edge (yellow arrow) apparent.  The profiles of (b) represent initial ARFI-induced displacement and recovery for a non-atherosclerotic vessel wall region (solid) and atherosclerotic region (dashed) under intraluminal pressures of 3 (blue) to 12 (red) kPa.  The non-atherosclerotic and atherosclerotic regions examined are marked on the B-Mode image of (a) by blue dots.  A two-dimensional parametric image of peak ARFI-induced displacements is shown in (c), with color representing peak displacement in microns, per the adjacent colorbar.  Masked blood signal is mapped to the color gray.  Time to 67% recovery from peak ARFI-induced displacement is illustrated in (d), with color coding representing recovery time in milliseconds.  The arterial wall beneath the raised atherosclerotic focal plaque is boxed.

Acoustic radiation force has been demonstrated for a variety of clinical imaging applications, including differentiating malignant lesions from fluid-filled cysts in the breast (Nightingale et al., 1999), manipulating the vitreous humor of the eye (Walker et al., 1999), and vibrating tissue at confocal transducers’ beat frequencies (Fatemi et al., 1999). More recently, ARFI imaging has been implemented for assessing blood clot formation in vitro (Viola et al., 2004), monitoring chemical and thermal ablations in vivo (Fahey et al., 2004) , and streaming blood in arteries and veins in vivo. In application to CVD, ARFI imaging has been successful for isolating regions of atherosclerosis via surveying arterial wall mechanical properties in in vivo and ex vivo human investigations (Trahey et al., 2004).

Read the rest of this entry »