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Thứ Năm, 29 tháng 5, 2014

Dr. Birnholz on Ultrasound Part 15

In other news, Dr. Jason Birnholz is back with his latest Practice of Ultrasound installment. The article looks back at Dr. Birnholz's involvement in ultrasound from its origins, with the establishment of one of the first sonography clinical services at Massachusetts General Hospital, through today, with ultrasound becoming an increasingly common tool used throughout healthcare. He also ponders the rise of what he calls "checklist" ultrasound, in which the exam is performed by minimally trained healthcare personnel and ultrasound is used as a gateway to other imaging tools. This differs from the model of sonography performed by highly trained specialists who might be capable of rendering a diagnosis simply with the tools at hand. In today's era of point-of-care ultrasound and the "electronic stethoscope," it's clear that checklist imaging has won out. But that may not always be the case, especially with new ultrasound technology in development that could lead to major improvements in image quality.

Thứ Sáu, 23 tháng 5, 2014

Liver Cancer Ultrasound Screening

Liver Cancer Ultrasound Screening Can Improve Survival of Cirrhosis Patients

By Medimaging International staff writers
Posted on 20 May 2014




Image: Dr. Amit Singal, assistant professor of internal medicine and clinical sciences at the University of Texas Southwestern Medical Center – author of the paper “Early Detection, Curative Treatment, and Survival Rates for Hepatocellular Carcinoma Surveillance in Patients with Cirrhosis: A Meta-analysis” published in the Public Library of Science Medical Journal (Photo courtesy of the University of Texas Southwestern Medical Center).

Liver cancer survival rates could be improved if more individuals with cirrhosis are screened for tumors using inexpensive ultrasound scanning and blood tests, according to a recent review.

The meta-analysis of 47 studies involving more than 15,000 patients discovered that the three-year survival rate was much higher among patients who received liver cancer screening—51% for patients who were screened compared to 28% of unscreened patients. The review also found that cirrhosis patients who were screened for liver cancer were more likely to receive curative treatment instead of palliative care.

“Curative therapies, such as surgery or a liver transplant, are only available if patients are found to have liver cancer at an early stage. Unfortunately, right now, only a minority of patients’ cancers are found at an early stage,” said Dr. Amit Singal, an assistant professor of internal medicine and clinical sciences at the University of Texas (UT) Southwestern Medical Center (Dallas, USA), and medical director of the Liver Tumor Clinic in the Harold C. Simmons Cancer Center.

Dr. Singal’s findings, published April 1, 2014, in the Public Library of Science Medical Journal, are especially significant for Texas because the state has high rates of fatty liver disease and hepatitis C, both of which are correlated with cirrhosis. Texas also has the second highest incidence of hepatocellular carcinoma (HCC), the most typical type of liver cancer in the United States. Many cases of HCC can be caught early with screening. “We have a simple test, an abdominal ultrasound which is painless and easy, but we found that less than 20% of at-risk people have the test done, largely due to providers failing to order it,” Dr. Singal said.

Dr. Singal reported that he hopes his study will encourage both patients and doctors to request ultrasound screening. He noted that liver cancer screening is not yet recommended by the US Preventative Services Task Force, partly because a randomized study has not yet been done, which points to a conundrum in the field. When a randomized study was attempted in 2005, many patients chose to leave the study when they heard evidence that liver cancer screening could be so beneficial. None of the patients wanted to be the ones randomly chosen to not get the tests.

Dr. Singal hopes his findings will convince more cirrhosis patients and their doctors that screening is worthwhile. “Just because we don’t have a randomized trial doesn’t mean there isn’t a benefit. We’re stuck in the middle ground where we’ve gone halfway. People are starting to believe liver cancer screening is helpful, but there’s not enough evidence to prove a definite benefit,” Dr. Singal said. “Part of our goal is providing evidence to both patients and physicians that liver cancer screening is beneficial.”

Thứ Ba, 20 tháng 5, 2014

ARFI of NORMAL KIDNEY and HYDRONEPHROSIS in CHILDREN




Discussion
Hydronephrosis is an obstructive or non-obstructive nephropathy that is a commonly identified disease during pediatric abdominal ultrasonography. Congenital obstructive nephropathy constitutes the single most important identifiable cause of renal impairment in infants and children [10-12]. In obstructive nephropathy, interstitial fibrosis eventually develops and leads to a loss of nephrons [10].
Numerous papers that focus on the molecular biological mechanisms associated with renal interstitial fibrosis due to obstructive nephropathy have been recently published [10,13,14]. However, there is limited radiological research on renal interstitial fibrosis in the case of hydronephrosis. This could be attributed to the difficulty of detection, evaluation, and quantification of interstitial fibrosis by radiological methods.
There are many studies that explored ARFI measurements as a means of evaluating tissue stiffness, including several studies on kidneys. Gallotti et al. [6], Eiler et al. [7], and Goertz et al. [8] measured the ARFI velocities of normal kidneys in healthy adults.
Further, there have been several trials using ARFI in adult kidneys to evaluate renal masses, to assess renal allograft fibrosis, and to detect chronic kidney diseases [15-17]. However, there is a lack of studies involving ARFI measurements in young children. This could be attributed to the fact that the previously used low-frequency transducer is not effective in the case of such small patients.
However, the availability of the 4-9-MHz high-frequency linear transducer makes it possible to measure SWVs in small subjects. Recently, our group demonstrated normal values of SWVs using ARFI in pediatric abdominal organs including kidneys in 202 children with an average age of 8.1±4.7 years [1]. The mean SWVs were 2.19 m/sec for the right kidney and 2.33 m/sec for the left kidney in the above mentioned study. The previously reported mean SWVs in normal adult kidneys were 2.24-2.37 m/sec, with no significant difference between the right and the left kidney [6,8]. The median SWVs in normal kidneys in the present study were 1.75 m/sec without any difference between the right and the left ones. This value is relatively low as compared to that obtained in previous studies. However, this result is comparable with that of our previous study, which concluded that the mean ARFI SWV for the kidneys increased according to age in children less than 5 years of age [1].
In this study, we only included children under the age of 24 months. Only one study has been performed on the evaluation of diseased kidneys in children. Bruno et al. [5] conducted a study of ARFI measurements in pediatric patients with vesicoureteral reflux. The study suggested that ARFI can provide reliable information about the severity of renal damage and maybe useful in the diagnostic workup in children with a chronic reflux renal disease. However, the patient age in the study ranged from 8 to 16 years. Therefore, our study is the first report evaluating ARFI for hydronephrotic kidneys in young children.
We aimed to correlate SWVs with the hydronephrosis grade. Even though there are hydronephrosis grading systems on ultrasonography [11,18,19], these could not definitely differentiate between obstructive and non-obstructive hydronephrosis. Further, these systems cannot suggest the grade of renal parenchymal fibrosis. If SWVs have a correlation with the renal parenchymal stiffness, its measurement would be helpful in evaluating the status of a patient’s kidney. Further, SWV can show a continuous spectrum of stiffness.
On the other hand, the grading system has an ordinal scale that cannot show a continuous value. Therefore, elastography has a possibility of having an additional value to evaluate hydronephrosis. In our study, there was a significant difference in the median SWVs between normal kidneys (1.75 m/sec) and high-grade hydronephrotic kidneys (2.02 m/sec). This suggests that elasticity decreases and stiffness increases in high-grade hydronephrotic kidneys. However, ARFI measurements cannot differentiate the cause of stiffness change such as tissue fibrosis and edema. Further research with a large group of patients and pathologic correlation is needed.
We also compared SWVs for a hydronephrotic kidney with and without UPJO. Further, there were only seven patients proven to have UPJO during the study period. The mean ARFI velocities were 0.69-2.51 m/sec for hydronephrotic kidneys without UPJO and 1.54-2.72 m/sec for those with UPJO; there was no statistical difference. Kidneys with VUR and a parenchymal scar change also exhibited no remarkable difference in SWVs. This could be attributed to the small number of patients, variable interstitial fibrosis of the UPJO group, and heterogeneous parenchymal scar change in the refluxing kidneys. This needs further evaluation with a large number of patients.

This study has several limitations. Almost all previous studies performed in adults measured about 5-10 valid SWVs and used mean values. However, due to the characteristics of the pediatric patient group, only three valid SWVs were obtained in this study.
Repetitive measurements over a long time while subjects hold their breath is not possible in many children, particularly young children. Although only three valid ARFI velocities were attempted, two children could not tolerate the examinations and the success rate was 96%. Moreover, subjects were allowed to breathe freely during measurements. Thiscan increase the variability of SWV. The development of a method to measure SWV without breathholding would lead to more reliable results. 

The second limitation is the representativeness of the ARFI value.To represent a global kidney, measurement should be performed on multiple sites of the kidney, such as the upper, mid-, and lower poles. However, if the upper and lower poles are to be imaged, it is necessary to use a similar angle of incidence in all patients relative to the tubular system to avoid anisotropy issues. It is conceivable that shear waves generated within the kidney move at different velocities depending on the angle of incidence [20]. We tried to measure SWVs at the same portion of the mid-pole from the axial view, as parallel to the tubular system as possible in order to reduce the angle effect. The variation of the depth of the ROI position should also be considered.
We targeted renal parenchyma, including both the renal cortex and the medulla, from the axial view in each patient. Therefore, we might expect that the depth of the ROI position would be different between patients and could increase according to the body size. Further study is needed to evaluate the effect of the depth of the ROI position and the body size in children. 

The fourth limitation is that we considered the contralateral kidneys without hydronephrosis as normal in the hydronephrosis group. Even though we demonstrated no significant difference in SWVs between normal kidneys in the normal group and contralateral kidneys in the hydronephrosis group, there could have been a physiological change in the bilateral kidneys of the hydronephrosis group.

In conclusion, obtaining ARFI measurements of kidneys using a high-frequency transducer is feasible in very young pediatric patients. The median SWV of normal kidneys in children under the age of 24 months was 1.75 m/sec. These velocities increased in high-grade hydronephrotic kidneys but were not helpful in differentiating hydronephrotic kidneys with and without UPJO.


Beomseok Sohn; Myung-Joon Kim; Sang Won Han; Young Jae Im; Mi-Jung Lee.

AT MEDIC CENTER:

We applied ARFI technique from Siemens S2000 to evaluate whether fibrotic process existing in adult hydronephrosis.
Using 1-4 MHz convex probe we calculated in 3 positions of hydronephotic kidney due to  obstruction [stone, outside compression] (n=27 cases), due to ureteropelvic junction obstruction [UPJO] (n=30 cases]. We had a control group of normal kidney (n=36 cases).











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Experience Matters in point-of-care Ultrasound of Appendicitis


Experience matters in point-of-care ultrasound
By Erik L. Ridley, AuntMinnie staff writer
May 19, 2014 -- Experienced sonologists had significantly higher sensitivity for diagnosing appendicitis with point-of-care ultrasound than sonologists with less experience, in a study from Mount Sinai School of Medicine. Either way, though, it's important not to rely only on point-of-care ultrasound to rule out the condition.

 In the prospective study of 150 patients, experienced sonologists' sensitivity was nearly 30% higher than that of their less experienced colleagues.
"To minimize the possibility of errors, sonologists should avoid ruling out appendicitis based on [point-of-care ultrasound] results alone," said Dr. James Tsung from the department of emergency medicine. "So you need the clinical picture, and if there's uncertainty, certainly proceed with radiology imaging."
He presented the research during a scientific session at the recent American Institute of Ultrasound in Medicine (AIUM) annual meeting.
The experience effect
While it's well-known that ultrasound is an operator-dependent imaging modality, the effect of operator experience on point-of-care ultrasound hasn't yet been studied, according to Tsung.
In medicine, misdiagnosis-related errors are much more common than medication errors and can lead to poor patient outcomes. These types of errors can be minimized, however, by understanding the relationship between operator experience and a test's performance characteristics, he said.
With that in mind, the Mount Sinai team sought to evaluate the effect of operator experience on the sensitivity and specificity of point-of-care ultrasound in a prospective study of 150 children.
For inclusion in the study, patients had to be 21 years or younger, have abdominal pain with nausea and/or vomiting, and require imaging or laboratory evaluation for suspected appendicitis. Patients were excluded if they required immediate resuscitation, had prior imaging for suspected appendicitis, or had known inflammatory bowel disease.
Point-of-care ultrasound exams were considered positive for appendicitis based on standard sonographic definitions for appendicitis, while negative results included a normal appendix finding and also nondiagnostic studies. For the purposes of the study, the gold standards were operating-room/pathology reports for patients who required surgical operations, and a three-week phone follow-up for nonoperative patients.
Experienced sonologists enrolled more than 25 patients in the study and had diagnosed appendicitis using point-of-care ultrasound prior to the study test, while novice sonologists enrolled fewer than 25 patients and hadn't diagnosed appendicitis yet using point-of-care ultrasound.
The researchers then stratified the test performance characteristics by novice versus experienced sonologists, analyzing the relationship between operator experience, prevalence of appendicitis, and the rate of nondiagnostic scans.
Of the 150 patients who received point-of-care ultrasound, 61 (40.6%) exams were performed by an experienced sonologist and 89 (59.3%) were performed by a novice. Patients went on to receive either follow-up radiology ultrasound or CT; those with positive imaging findings went on to the operating room, while the rest were admitted or discharged.
There was an overall appendicitis prevalence rate of 33.3% in the study, which is in line with prior literature for ultrasound and appendicitis. No missed cases were discovered at the three-week phone follow-up, and there were no negative laparotomies in the operative patients.
Higher sensitivity
The 61 studies performed by the experienced sonologists included 48 negative and 13 positive exams, while the 89 studies handled by the novice sonologists included 67 negative and 22 positive exams.
Sensitivity and specificity of point-of-care ultrasound
SensitivitySpecificity
Overall point-of-care ultrasound (150 patients)60%94%
Experienced sonologists (63 patients)80%98%
Novice sonologists (89 patients)51.4%93%
Radiology ultrasound (117 patients)62.5%99.3%
The overall sensitivity and specificity for point-of-care ultrasound is in line with the literature, Tsung said.
"If you look at the spread between sensitivity [for experienced and novice sonologists], you've got like a 28 [percentage point] spread, whereas the spread between novice and experienced in specificity is much smaller, about five [points]" he said. "If you look at radiology ultrasound, they had a relatively low sensitivity relative to what's in the literature, but their specificity was excellent."
Tsung noted that point-of-care ultrasound preceded the radiology ultrasound study, an order that will naturally bump up the specificity of the radiology ultrasound study. In addition, radiology residents performed radiology ultrasound at their institution, which is why sensitivity was lower than would be expected.
"A lot of the residents just weren't comfortable with the scan," he said.
Additional point-of-care ultrasound results
Nondiagnostic studiesAppendicitis prevalence
Overall point-of-care ultrasound69%33.3%
Experienced sonologists67%24.6%
Novice sonologists71%39.3%
Radiology ultrasound59%37.6%
"What [the appendicitis prevalence numbers] suggest is that the patients the novices tended to enroll [in the study] probably had more apparent appendicitis," he said.
Based on the differences between the two sonologist groups, the researchers concluded that operator experience had a greater effect on sensitivity to rule out appendicitis compared with specificity.
"Our ability to rule out pathology is more operator-dependent than specificity," he said.

Tsung acknowledged a number of limitations to the research; for example, it was a single-center study, relied on a convenience sample, and utilized a small sample size for subgroup analysis, he said.

Thứ Sáu, 9 tháng 5, 2014

New Ultrasound Device May Help to Detect Risk for Stroke and Heart Attacks

New Ultrasound Device May Help to Detect Risk for Stroke and Heart Attacks

By Medimaging International staff writers
Posted on 06 May 2014




Image: The new ultrasound device will help identify vulnerable plaque that increases risk of heart attack or stroke (Photo courtesy of Xiaoning Jiang).
New prototype ultrasound technology could help detect arterial plaque that is at high risk of breaking off and causing a heart attack or stroke.

Plaque around the heart accumulates in arteries as people get older. Some types of plaque are considered to be “vulnerable,” meaning that they are more likely to detach from the artery wall and cause heart attack or stroke.

Researchers from North Carolina (NC) State University (Raleigh, USA) and the University of North Carolina at Chapel Hill (USA) have developed the ultrasound device. “Existing state-of-the-art technologies are capable of determining if plaque is present in the arteries, but can’t tell whether it’s vulnerable. And that makes it difficult to assess a patient’s risk,” says Dr. Paul Dayton, coauthor of a paper on the new device and professor in the joint biomedical engineering department at NC State and Chapel Hill. “Our goal was to develop something that could effectively identify which plaques are vulnerable.”

There are two ultrasound techniques that can help detect vulnerable plaques, but both make use of contrast agents called “microbubbles.” The first technique is to identify vasa vasorum in arteries, which are clusters of small blood vessels that frequently infiltrate arterial plaque, and which are considered indicators that a plaque is vulnerable. When microbubbles are injected into an artery, they move with the blood flow. If vasa vasorum are present, the microbubbles will flow through these blood vessels as well, effectively highlighting them on ultrasound images.

The second technique is called molecular imaging, and relies on the use of “targeted” microbubbles. These microbubbles fasten themselves to specific molecules that are more likely to be found in vulnerable plaques, making the plaques emphasized on ultrasound images.

“The problem is that existing intravascular ultrasound technology does not do a very good job in detecting contrast agents,” stated Dr. Xiaoning Jiang, an NC State associate professor of mechanical and aerospace engineering, an adjunct professor of biomedical engineering and coauthor of the article. “So we’ve developed a dual-frequency intravascular ultrasound transducer which transmits and receives acoustic signals. Operating on two frequencies allows us to do everything the existing intravascular ultrasound devices can do, but also makes it much easier for us to detect the contrast agents—or microbubbles—used for molecular imaging and vasa vasorum detection.”

The prototype device has performed well in laboratory testing; however, the researchers reported that they are still enhancing the technology. They plan to establish preclinical studies in the near future.

The study was published in the May 2014 issue of the journal IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.

Related Links:
North Carolina State University
University of North Carolina at Chapel Hill

ULTRASOUND REDUCES PNEUMOTHORAX RATE of THORACENTESIS


Abstract (provisional)
Background
Malignant pleural effusion (MPE) is an extremely common problem affecting cancer patients, and thoracentesis is an essential procedure in an attempt to delineate the etiology of the fluid collections and to relieve symptoms in affected patients. One of the most common complications of thoracentesis is pneumothorax, which has been reported to occur in 20% to 39% of thoracenteses, with 15% to 50% of patients with pneumothorax requiring tube thoracostomy.
The present study was carried out to assess whether thoracenteses in cancer patients performed with ultrasound (US) guidance are associated with a lower rates of pneumothorax and tube thoracostomy than those performed without US guidance.
Methods
A total of 445 patients were recruited in this retrospective study. The medical records of 445 consecutive patients with cancer and MPE evaluable for this study, undergoing thoracentesis at the Oncology-Hematology and Internal Medicine Departments, Piacenza Hospital (Italy) were reviewed.
Results
From January 2005 to December 2011, in 310 patients (69.66%) thoracentesis was performed with US guidance and in 135 (30.34%) without it. On post-thoracentesis imaging performed in all these cases, 15 pneumothoraces (3.37%) were found; three of them (20%) required tube thoracostomy. Pneumothorax occurred in three out of 310 procedures (0.97%) performed with US guidance and in 12 of 135 procedures (8.89%) performed without it (P <0 .0001="">
Conclusions
The routine use of US guidance during thoracentesis drastically reduces the rate of pneumothorax and tube thoracostomy in oncological patients, thus improving safety as demonstrated in this study.


GIANT CELL ARTERITIS and CRANIAL ULTRASOUND









Thứ Tư, 7 tháng 5, 2014

Sjogren's Syndrome Classification

Ultrasound Improves Sjogren's Syndrome Classification
By David Douglas
May 03, 2014

NEW YORK (Reuters Health) - Salivary gland ultrasonography (SGUS) enhances American College of Rheumatology (ACR) classification of patients with Sjögren's syndrome (SS) and in the future should be included in evaluations, according to French investigators.

"In this study, we confirm that salivary gland ultrasonography has a large clinical impact for the diagnosis of primary Sjögren's syndrome," Dr. Divi Cornec told Reuters Health by email. "This non-invasive, easily accessible tool should be included in the diagnostic work-up for suspected Sjögren's syndrome. An international study group has been recently created to definitely validate the procedure."






In an April 4th online paper in Rheumatology, Dr. Cornec of Hopital de la Cavale Blanche, Brest and colleagues note that in 2012, the ACR issued new classification criteria for SS. These were selected based on expert opinion but none reflects salivary gland function and morphology, which are altered in SS.

To examine the utility of SGUS in augmenting the diagnostic performance of the ACR approach, the researchers examined 101 patients with suspected SS. Among inclusion criteria were subjective ocular or oral dryness, recurrent or bilateral parotidomegaly or laboratory abnormalities suggesting SS. An SGUS echostructure score of 2 or more was considered abnormal.

All cases were reviewed by a panel of three experts blinded to the SGUS findings and SS was diagnosed in 45 patients. Similar proportions of patients with and without SS had an ocular staining score at or beyond 3.

As covered in the ACR classification criteria, adding rheumatoid factor positivity and an antinuclear antibody titer of 1.320 or more as an alternative to anti-SSA/SSB positivity increased the sensitivity of the serological item without modifying specificity compared with using anti-SSA/SSB alone.

SGUS alone gave a sensitivity of 60.0% and a specificity of 87.5%. Adding the SGUS score to the ACR criteria increased the sensitivity from 64.4% to 84.4% and only "slightly" decreased specificity, from 91.1% to 89.3%.

SGUS, say the researchers, "is simple, non-invasive, widely available, non-irradiating and less expensive than other imaging techniques." Adding it "substantially improved the diagnostic performance of the 2012 ACR criteria set."

Thus they conclude that SGUS "should be included in future consensual classification criteria for SS."

SOURCE: http://bit.ly/R825Kg

Rheumatology 2014.


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Chủ Nhật, 4 tháng 5, 2014

SUPERSONIC SHEAR IMAGING in MSK SYSTEM



Dear Editor,
The skeletal muscle is an anisotropic, viscoelastic, and complex passive and active tissue. Therefore, the in vivo evaluation of the biomechanical properties of the skeletal muscle is a complex issue. A new ultrasound-based technique, supersonic shear imaging (SSI), can be used to quantify soft tissue stiffness [1]. 

Supersonic shear imaging is based on the conventional ultrasound probe, which induces an ultrasonic radiation force deep within the muscle. Propagation of the resulting shear waves is then imaged with the same probe at an ultra-fast frame rate. The shear elasticity of a tissue can be mapped quantitatively from this propagation movie. This approach may provide a complete set of quantitative and in vivo parameters describing biomechanical properties of the skeletal muscle [2]. Recent studies have shown excellent intra- and interobserver reliability of the muscle shear elastic modulus measured by SSI [3,4]. Several studies also imply that SSI is a promising tool for evaluating muscle conditions because it may provide an indirect estimation of passive muscle force [5]. It may also provide a more accurate estimation of individual muscle force, compared to surface electromyography [6]. Different pathologies of the skeletal muscle (e.g., muscle fibrosis, muscular dystrophy, and spasticity in upper motor neuron diseases) may change the muscle shear elastic modulus. Thus, SSI may contribute to the improved diagnosis and management of neuromuscular and orthopedic diseases. However, a few considerations should be addressed.

First, all current studies have investigated healthy participants. The diagnostic value of SSI in patients should be further studied.

Second, few studies have focused on the tendon in which pathological changes may interfere with muscle function. The tendon has a much higher elastic modulus and smaller volume in comparison to the muscle, which makes SSI challenging for examining tendinopathy.   

Third, because skeletal muscle is compressible, variations of the probe pressure on the muscle may cause different shear elastic modulus. The higher pressure on the muscle, the higher is shear elastic modulus. A very light contact between the probe and the skin is recommended when examining muscle elasticity.

Fourth, the region of interest (ROI) in SSI for obtaining shear elastic modulus is circular. Therefore, its representation of an entire muscle is questionable. A standardized surface landmark and the depth of ROI should be clearly described. The average of the data from multiple ROIs may be calculated to minimize measurement errors.

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