Tag: ultrasound

Categories : CancerTags :

Ultrasound Scans Proven Effective in Prostate Cancer Diagnosis

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Results from a clinical trial showed that ultrasound scans are effective in prostate cancer diagnosis, which would be a cheaper option than MRI for low- and middle income countries. The study is published in Lancet Oncology.

“MRI scans are one of the tests we use to diagnose prostate cancer,” said Professor Hashim Ahmed, lead author of the study and Chair of Urology at Imperial College London. “Although effective, these scans are expensive, take up to 40 minutes to perform and are not easily available to all. Also, there are some patients who are unable to have MRI scans such as those with hip replacements or claustrophobia fears.  As cancer waiting lists build as a result of the COVID pandemic, there is a real need to find more efficient and cheaper tests to diagnose prostate cancer.

“Our study is the first to show that a special type of ultrasound scan can be used as a potential test to detect clinically significant cases of prostate cancer.  They can detect most cases of prostate cancer with good accuracy, although MRI scans are slightly better.

“We believe that this test can be used in low and middle income settings where access to expensive MRI equipment is difficult and cases of prostate cancer are growing.”

Prostate cancer develops slowly and symptoms such as the blood in the urine do not appear until the disease has developed. It usually affects men over 50 and often men with a family history of the disease. Black men are disproportionately impacted by the disease and prostate cancer deaths now exceed those from breast cancer.

One of the principal means of prostate cancer diagnosis is a multi-parametric MRI (mpMRI) scan. However, the 40-minute scan costs £350–450 (R7000-9000).

This new study tested multiparametric ultrasound (mpUSS) to image the prostate. Elastography examines tissue hardness, doppler and contrast-enhancement with microbubbles measures blood flow. As cancers are denser and have greater blood supply, they show up more clearly.
While mpUSS is more widely available than mpMRI, no large-scale studies have been done thus far to validate its effectiveness as a test to detect prostate cancer cases.

For the trial the team recruited 370 men at risk of prostate cancer. They were identified following initial tests such as a prostate-specific antigen (PSA) test and/or an abnormal digital rectal examination.

The men underwent both mpUSS and mpMRI scans at separate visits. This was then followed by biopsies for 257 patients who had a positive mpUSS or mpMRI test result. Cancer was detected in 133 men, with 83 men diagnosed with clinically significant cancer.

Individually, mpUSS detected 66 cases of clinically significant cancer compared to mpMRI which detected 77 cases.

Although mpUSS detected 4.3% fewer clinically-important prostate cancers compared to mpMRI, this method would lead to 11.1% more patients being biopsied as a result of false positives from the mpUSS.

The researchers believe that mpUSS could be an alternative to mpMRI as a first test for patients at risk of prostate cancer, particularly where mpMRI cannot be carried out. As both imaging tests missed clinically-important cancers detected by the other, using both would increase the detection of clinically-important prostate cancers overall.

Source: Imperial College London

Categories : NeurologyTags :

Ultrasound Treatment can Target Neural Circuits of Epilepsy

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Image credit: Dr Yu

A pioneering new study from Taiwan showed that focused ultrasound, which can be used to non-invasively target circuits in the brain, may benefit some patients with epilepsy who experience seizures which remain unresponsive to standard anti-seizure medications.

The results showed that of six patients with drug-resistant seizures, two patients had fewer seizures within three days of receiving focused ultrasound; however, one patient showed signs of more frequent subclinical seizures (which are not felt by the individual). The findings from the study were published in the journal Epilepsia.

Imaging tests performed after the treatment show that there were no negative effects on the brain. One patient reported a sensation of heat on the scalp during the treatment, and another patient experienced temporary memory impairment that resolved within three weeks.

“Neuromodulation is an alternative treatment for drug-resistant epilepsy. Compared with the present modalities used in neuromodulation for epilepsy, focused ultrasound can access deeper brain regions and focus on the main target of the epileptic network in a relatively less invasive approach,” explained senior author Hsiang-Yu Yu, MD, of Taipei Veterans General Hospital, in Taiwan. “It gives new hope and sheds new light for patients with drug-resistant epilepsy.”

Source: Wiley

Categories : Pain ManagementTags :

Transcranial Focused Ultrasound for Chronic Pain Relief

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Source: CC0 Creative Commons

A rodent study has demonstrated the potential for transcranial focused ultrasound (tFUS) to relieve chronic pain and other symptoms.

Neuromodulation, or therapeutic stimulation of neurons with electrical energy. chemicals or potentially with acoustic waves, can amplify or dampen neuronal impulses in the brain or body to relieve symptoms such as pain or tremor.

Ultrasound is a promising non-invasive, non-surgical type of neuromodulation. It offers a temporary modulation that can be tuned for a desired effect. In this study, researchers have shown that it can be targeted at neurons with specific functions.

A team led by Bin He, PhD, professor of biomedical engineering at Carnegie Mellon University, and funded in part by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), has demonstrated the potential of a neuromodulation approach that uses low-intensity ultrasound energy, called transcranial focused ultrasound-;or tFUS. In a paper published in Nature Communications, the authors describe the use of tFUS in rodent experiments, demonstrating the non-invasive neuromodulation alternative.

Moria Bittmann, PhD, Director of the Program in Biorobotic Systems, National Institute of Biomedical Imaging and Bioengineering, said: “Transcranial focused ultrasound is a promising approach that could be used to treat forms of chronic pain, among other applications. In conditions where symptoms include debilitating pain, externally generated impulses of ultrasound at controlled frequencies and intensity could inhibit pain signals.”

The researchers designed an assembly that included an ultrasound transducer and a multi-electrode array, which records neuronal data. During experiments with anaesthetised rodents, the researchers sent acoustic pulses into the brain cortex, targeting specific neurons, while recording change in electrophysiological signals from different neuron types.

When neurons transmit signals, whether engaging the senses or controlling movement, the firing of that signal across the synapse is termed a spike. The researchers observed two types of neurons: excitatory and inhibitory neurons.

When using tFUS to emit repeated bursts of ultrasound stimulation directly at excitatory neurons, the researchers saw an elevated impulse rate, or spike. Inhibitory neurons subjected to the same tFUS energy however did not display a significant spike rate disturbance. This showed that the ultrasound signal can be transmitted through the skull to selectively activate specific neuron sub-populations, in effect targeting neurons with different functions.

“Our research addresses an unmet need to develop non-toxic, non-addictive, non-pharmacologic therapies for human use,” said Prof He. “We hope to further develop the tFUS approach with variation in ultrasound frequencies and to pursue insights into neuronal activity so that this technology has the optimal chance for benefiting brain health.”

There are many broad applications for this research. Prof He believes non-invasive tFUS neuromodulation could be used to facilitate treatment for many people suffering from pain, depression and addiction. “If we can localise and target areas of the brain using acoustic, ultrasound energy, I believe we can potentially treat a myriad of neurological and psychiatric diseases and conditions,” Prof He said.

Source: National Institute of Biomedical Imaging and Bioengineering

Categories : Medical Research & Technology Neurodegenerative DiseasesTags :

MRI and Ultrasound Combo Opens Blood-brain Barrier

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In a mouse model study of MRI-guided focused ultrasound-induced blood-brain barrier (BBB) opening at MRI field strengths ranging from ­approximately 0 T (outside the magnetic field) to 4.7 T, the static magnetic field dampened the detected microbubble cavitation signal and decreased the BBB opening volume. Credit: Washington University School of Medicine in St. Louis

Using a combination of ultrasound, MRI field strength and microbubbles can open the blood-brain barrier (BBB) and allow therapeutic drugs to reach the diseased brain location with MRI guidance. 

Using the physical phenomenon of cavitation, it is a promising technique that has been shown safe in patients with various brain diseases, such as Alzheimer’s diseases, Parkinson’s disease, ALS, and glioblastoma.
While MRI has been commonly used for treatment guidance and assessment in preclinical research and clinical studies, until now, researchers did not know the impact that MRI scanner’s magnetic field had on the BBB opening size and drug delivery efficiency.

Hong Chen, associate professor of biomedical engineering at Washington University in St. Louis, and her lab have found for the first time that the magnetic field of the MRI scanner decreased the BBB opening volume by 3.3-fold to 11.7-fold, depending on the strength of the magnetic field, in a mouse model. The findings were in Radiology.

Prof Chen conducted the study on four groups of mice. After they were injected microbubbles, three groups received focused-ultrasound sonication at different strengths of the magnetic field: 1.5 T (teslas), 3 T and 4.7 T, and one group was never exposed to the field. 

The researchers found that the microbubble cavitation activity, or the growing, shrinking and collapse of the microbubbles, decreased by 2.1 decibels at 1.5 T; 2.9 decibels at 3 T; and 3 decibels at 4.7 T, compared with those that had received the dose outside of the magnetic field. Additionally, the magnetic field decreased the BBB opening volume by 3.3-fold at 1.5 T; 4.4-fold at 3 T; and 11.7-fold at 4.7 T. No tissue damage from the procedure was seen.

Following focused-ultrasound sonication, the team injected a model drug, Evans blue dye, to investigate whether the magnetic field affected drug delivery across the BBB. The images showed that the fluorescence intensity of the Evans blue was lower in mice that received the treatment in one of the three strengths of magnetic fields compared with mice treated outside the magnetic field. The Evans blue trans-BBB delivery was decreased by 1.4-fold at1.5 T, 1.6-fold at 3.0 T and 1.9-fold at 4.7 T when compared with those treated outside of the magnetic field.

“The dampening effect of the magnetic field on the microbubble is likely caused by the loss of bubble kinetic energy due to the Lorentz force acting on the moving charged lipid molecules on the microbubble shell and dipolar water molecules surrounding the microbubbles,” said Yaoheng (Mack) Yang, a doctoral student in Prof Chen’s lab and the lead author of the study.

“Findings from this study suggest that the impact of the magnetic field needs to be considered in the clinical applications of focused ultrasound in brain drug delivery,” Prof Chen said.

In addition to brain drug delivery, cavitation is also used in several other therapeutic techniques, such as histotripsy, the use of cavitation to mechanically destroy regions of tissue, and sonothrombolysis, a therapy used after acute ischaemic stroke. The magnetic field’s damping effect on cavitation is expected to affect the treatment outcomes of other cavitation-mediated techniques when MRI-guided focused-ultrasound systems are used.

Source: Washington University in St. Louis

Journal information: Yang, Y., et al. (2021) Static Magnetic Fields Dampen Focused Ultrasound–mediated Blood-Brain Barrier Opening. Radiology. doi.org/10.1148/radiol.2021204441. 

Categories : Medical Research & Technology Neurodegenerative DiseasesTags :

Precise Ultrasound Heating of Neurons Could Treat Neurological Disorders

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Image source: Fakurian Design on Unsplash

A multidisciplinary team at Washington University in St. Louis has developed a new brain stimulation technique using focused ultrasound that is able to turn specific types of neurons in the brain on and off and precisely control motor activity without surgical device implantation.

Being able to turn neurons on and off can treat certain neurological disorders such as Parkinson’s disease and epilepsy. Used for over six decades, deep brain stimulation techniques have had some treatment success in neurological disorders, but those require surgical device implantation. 

The team, led by Hong Chen, assistant professor of biomedical engineering in the McKelvey School of Engineering and of radiation oncology at the School of Medicine, is the first to provide direct evidence showing noninvasive activation of specific neuron types in mammalian brains by combining an ultrasound-induced heating effect and genetics, which they have named sonothermogenetics. It is also the first work to show that the ultrasound- genetics combination can robustly control behaviour by stimulating a specific target deep in the brain.

The results of the three years of research were published online in Brain Stimulation. 

“Our work provided evidence that sonothermogenetics evokes behavioural responses in freely moving mice while targeting a deep brain site,” Chen said. “Sonothermogenetics has the potential to transform our approaches for neuroscience research and uncover new methods to understand and treat human brain disorders.”

Chen and colleagues delivered a viral construct containing TRPV1 ion channels to genetically-selected neurons in a mouse model. Then, they delivered small pulses of heat generated by low-intensity focused ultrasound to the selected neurons in the brain via a wearable device. The heat, only a few degrees warmer than body temperature, activated the TRPV1 ion channel, which then acted as a switch to turn the neurons on or off.

“We can move the ultrasound device worn on the head of free-moving mice around to target different locations in the whole brain,” said Yaoheng Yang, first author of the paper and a graduate student in biomedical engineering. “Because it is noninvasive, this technique has the potential to be scaled up to large animals and potentially humans in the future.”

Building on prior research from his lab, professor of biomedical engineering Jianmin Cui and his team found for the first time that ion channel activity can be influenced by ultrasound alone, possibly leading to new and noninvasive ways to control the activity of specific cells. They discovered that focused ultrasound modulated the currents flowing through the ion channels on average by up to 23%, depending on channel and stimulus intensity. Following this work, researchers found close to 10 ion channels with this capability, but all of them are mechanosensitive, not thermosensitive.

The work also builds on the concept of optogenetics, the combination of the targeted expression of light-sensitive ion channels and the precise delivery of light to stimulate neurons deep in the brain. While optogenetics has increased discovery of new neural circuits, it has limited penetration depth due to light scattering, requiring surgical implantation of optical fibres to reach deeper into the brain.

Sonothermogenetics has the promise to target any location in the mouse brain with millimetre-scale resolution without causing any damage to the brain, Chen said. She and her team are further refining the technique and validating their work.

Source: Sci Tech Daily

Journal information: Yaoheng Yang et al, Sonothermogenetics for noninvasive and cell-type specific deep brain neuromodulation, Brain Stimulation (2021). DOI: 10.1016/j.brs.2021.04.021

Categories : CancerTags :

New Ultrasonic Tumour Therapy

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A new technique has been developed that uses ultrasound to vapourise encased nano-droplets, at the tumour site. This technology could be used to image the tumour, damage it or even deliver chemotherapy drugs with precision.

Existing applications of ultrasound therapy include thermal excitation of tissues, for example to dilate blood vessels, and creating cavitation to break up kidney stones. Ultrasonic toothbrushes have also been shown to remove dental plaque with better efficiency than conventional toothbrushes, and about the same as that of mechanical electrical toothbrushes. Micrometre-sized droplets, encased in a stabilising shell, can already be visualised with ultrasound, but these are too large to enter tumours. Nanometre-sized droplets can do so, however.

Vapourisation is tricky to control in reality, since the process requires a point of nucleation. The researchers demonstrated an efficient way to achieve vapourisation: by applying a frequency at the exact resonant frequency of the droplet, the pressure inside suddenly drops and the liquid vapourises. This is much the same principle as shattering a crystal glass by bombarding it with sound at its resonant frequency.

The researchers used hydrofluorocarbons,  which have a very low boiling point,   for the droplets. The resonance of the droplet being six times higher makes vapourisation much easier. The speed of sound of the droplet fluid being lower than the speed of sound in the bodily fluids surrounding it.
This resonant droplet vapourisation technology has a number of possible medical applications. The bubbles from the bursting droplets could be used to physically damage the tumour. Or, the droplets could contain chemotherapy drugs and made to break open precisely inside the tumour and reducing exposure of the rest of the body.

Source: News-Medical.Net

Journal information: Lajoinie, G. et al. (2021) High-Frequency Acoustic Droplet Vaporization is Initiated by Resonance’ by Guillaume Lajoinie, Tim Segers, and Michel Versluis. Physical Review Letters. doi.org/10.1103/PhysRevLett.126.034501.