REVERBERATION ARTEFACTS IN LUNG US, WFUMB POSITION PAPER

Abstract
The analysis of vertical reverberation artefacts is an essential component of the differential diagnosis in pulmonary ultrasound. Traditionally, they are often, but not exclusively, called B-line artefacts (BLA) and/or comet tail artefacts (CTA), but this view is misleading.
In this position paper we clarify the terminology and relation of the two lung reverberation artefacts BLA and CTA to specifc clinical scenarios. BLA are defned by a normal pleura line and are a typical hallmark of cardiogenic pulmonary edema after exclusion of certain pathologies including pneumonia or lung contusion, whereas CTAs show an irregular pleura line representing a variety of parenchymal lung diseases. The dual approach using low frequency transducers to determine BLA and high frequency transducer to determine the pleural surface is recommended.

Keywords: lung ultrasound; artefact; B-lines; comet tails; guidelines; misdiagnosis

Suggested approach:

The transducer should be positioned such that the emenating ultrasound beam perpendicularly intersects
the surface of the lung to maximize likelihood of seeing all BLA and CLA as well as A line artifacts (fig 1).
A recent study highlighted the potentially detrimental effects of placing the focal zone below the pleural line,using spatial compounding, higher frequency and tissue harmonics [14]. Once machine settings and transducer orientation have been optimized, we suggest that two most important and distinct vertical lung artefacts should be differentiated: BLA and CTA. While true BLA (fig 2) originate from a smooth pleural reflex due to cardiogenic pulmonary edema and present in a diffuse pattern, CTAs are seen in many lung disorders with irregular and fragmented pleural reflexes and can be focal or diffuse (fig 3).
Hence, the initial step should be to determine if there is evidence for diffuse pulmonary disease or defned focal or localized pathology. Focal lung pathologies by defnition should display vertical artifacts that are consistent with CTAs (fig 4).
Diffusely distributed vertical reverberation artefacts can be divided into two groups: with or without detectable pleural line irregularities and with stable or distally widening width:

1. The reverberation artefact (evaluated by low frequency transducer <5 MHz without interfering presets) is called BLA if arising from a smooth pleural line (evaluated by high frequency transducer ≥10 MHz). The BLA arises from edema within the interstitium, is well defned with stable width, hyperechoic and extending indefnitely (the entire depth, at least 10 cm), erasing A-lines and moving with lung sliding. It is important to realize that many modern ultrasound machines have post-processing and other features which will eliminate not only BLA but essentially all discernable image detail near the bottom of the screen at greater depths (fig 5).

2. The reverberation artefact is called CTA if arising from an irregular (or fragmented) pleural line (evaluated by high frequency transducer ≥10 MHz), changes in width (such as e a comet with narrow head and wide tail), is well defned, hyperechoic, and extending defnitely (<10 cm in depth) (evaluated by low frequency transducer <5 MHz without interfering presets). It is important to make sure image compounding is turned off to make sure the CTA is not distorted farther field [14].
The differentiation of BLA from CTA is also dependent on the technical adjustments of several external factors, including the type of ultrasound machine, transducers and probe frequencies [6].

In conclusion, the correct diagnosis of pulmonary edema (the etiology of which may be decided upon
through integration of ultrasound data with clinical presentation) in the emergency setting is crucial for the correct management of the patient. The differentiation between ultrasonographic BLA and CTA, using two types (high and low frequency) of transducers allows accurate differentiation between pulmonary edema and other cause of diffuse pulmonary pathology. Both can lead to acute respiratory failure but may require different clinical management. Localized pulmonary diseases representing with CTA are distinguished. Mixed forms of diffuse,but also diffuse and focal lung diseases have to be considered.


 

US accurate in diagnosing hand injuries

By Amerigo Allegretto, AuntMinnie.com staff writer

May 10, 2021 -- Ultrasound can accurately diagnose hand injuries while also being a fast, inexpensive, and potentially indispensable dynamic tool, according to research published April 29 in Ultrasound in Medicine and Biology.

Examining hand tendon injuries with sonography showed 100% accuracy, sensitivity, and specificity for diagnosing full-thickness hand tendon tears, as well as tenosynovitis of hand flexor tendons, according to a study led by Dr. Chris Nabil Hanna Bekhet from Ain Shams University in Cairo, Egypt.

"It also provides data that are important before diagnostic surgical exploration, and the process consumes less time than traditional wound exploration techniques or MRI," the authors wrote.

Hand and wrist injuries make up 28% of all musculoskeletal injuries and account for 14% to 30% of all patients treated in the emergency department. Tendon injuries are the second most common injuries, within injuries to the flexor tendons having debilitating consequences and high rates of reoperation.

Assessing hand injuries through clinical examination can overlook tendon injuries, and surgeons sometimes opt for explorative surgical methods to detect tendon injuries.

While using ultrasound to examine tendon injuries in the emergency department has its advantages, including eliminating the need for surgical approaches, it is not yet readily adopted by surgeons. This could be because clinicians lack education on how to use ultrasound to resolve clinical questions on the state of the tendon.

The study included 35 patients between September 2018 and January 2020 with trauma to the ventral surface of the hand and wrist who were presented to emergency departments or outpatient clinics. The subjects ranged from 18 to 58 years of age, with 24 patients being male and the other 11 being female.

The researchers examined 50 injured tendons in all flexor hand zones.

On ultrasound examination, 21 of the 50 injured tendons were reported to have complete tears, and 10 tendons were partially torn. The most common cause of injury was cut wounds by sharp objects (20 cases), with injury by a knife as the highest incidence.

In all, ultrasound was found to be statistically significant (p < 0.01) in predicting the surgical findings by correctly identifying the 21 fully lacerated tendons. It was also found to be statistically significant (p < 0.01) in predicting the surgical findings by correctly identifying partially torn tendons and determining the degree of the torn fibers.

The study's limitations included tests being performed by a single operating radiologist and the small sample size.

"More studies in this respect can popularize the technique among radiologists and clinicians," the authors wrote. "Our study also helps anchor the notion that musculoskeletal [ultrasound] could be widely employed for soft tissue structures, with their well-recognized advantages compared with other imaging techniques."

Sonographer vs. radiologist: What does it make?

• MoreBy Amerigo Allegretto, AuntMinnie.com staff writer

May 4, 2021 -- The clinical outcomes of children presenting with suspected acute appendicitis were similar regardless of whether they were scanned by sonographers or radiologists, according to research published April 29 in the Journal of the American College of Radiology.

In a study led by Dr. Leah Gilligan from Northwestern University in Illinois, researchers found that differences between radiologists and sonographers did not lead to clinically important outcomes in children undergoing ultrasound for suspected acute appendicitis. This also includes hospital readmission, surgical consultation, and appendectomy performance.

The team noted that this could also be because clinical care pathways could be sufficiently robust and that deviations in the performance of sonographers or radiologists are corrected by redundant safety nets.

"In other words, although sonographers and radiologists are known to vary in performance and interpretation skill, those differences do not seem to translate into meaningful differences in major clinical care outcomes for this indication," Gilligan colleagues wrote.

The team analyzed 9,283 appendix ultrasound scans with a mean patient age of 9.9 years; 58.2% of the patients were boys. For the study, ultrasound scans were performed by 31 sonographers and interpreted by another 31 radiologists.

The group found no statistically significant difference in outcomes between sonographers and radiologists. For example, children had the same appendectomy rate (20.3%) for both sonographers and radiologists, while the hospital admission frequency was also similar: 34% for sonographers and 33.5% for radiologists.

Despite the differences between sonographers and radiologists not being statistically significant, numerous other clinical and system factors do seem to be associated with these outcomes, the researchers found. Some of these were anticipated, such as ultrasound report impression, degree of abdominal tenderness, and white blood cell count.

One unanticipated factor that researchers noted was whether or not imaging was performed at the main hospital versus a satellite hospital.

They found that presentation to the satellite emergency department was associated with a decreased odds of hospital admission and surgical consultation, as well as an increased odds of hospital readmission within 30 days after adjusting for numerous clinical variables and system factors. The satellite hospital is staffed by the same sonographers and radiologists that work at the main hospital.

"As our study was not primarily designed to specifically investigate the impact of the location of imaging, the exact cause of these differences is unknown," they said.

The team also showed that assessing differences "probably" should not be used as a meaningful quality indicator in radiology department members performing and interpreting appendix ultrasound.

These results are potentially important because appendix ultrasound is widely performed and is a first-line test for suspected appendicitis at most dedicated pediatric hospitals, Gilligan and et al wrote.

AI can help to classify masses found on breast ultrasound

By Erik L. Ridley, AuntMinnie.com staff writer

May 3, 2021 -- Artificial intelligence (AI) software can aid radiologists in characterizing masses on screening breast ultrasound exams by improving cancer detection and reducing false positives, according to research from Yale University.

A research team led by Dr. Liane Philpotts retrospectively compared the performance of a commercial AI software algorithm with the original interpreting radiologist on over 200 lesions found on breast ultrasound. The group found that the software would have correctly classified all malignant cases and downgraded many lesions deemed initially to be suspicious.

"AI software appears to be a complementary tool for radiologists," Philpotts said during a presentation at the recent annual meeting of the American Roentgen Ray Society (ARRS). "Utilization of an AI decision support tool for whole-breast ultrasound findings could result in shifts away from the BI-RADS 3 category with the potential to increase the percentage of lesions characterized as benign, therefore increasing the sensitivity for malignant lesions."

Whole-breast screening ultrasound is becoming more commonplace across the U.S. and around the world, Philpotts said. Many states have passed laws regarding the notification of women with dense breasts, and in 2019, the U.S. Food and Drug Administration proposed national changes to the Mammography Quality Standards Act (MQSA) to require that women be notified of their breast density status.

"While these changes have increased the utilization of whole-breast screening ultrasound, the management of incidental solid masses found during these examinations is not well established," Philpotts added.

In their study, the researchers sought to establish a baseline performance for radiologists managing these masses and to determine whether an AI system -- Koios DS for Breast from Koios Medical -- could be used to improve diagnostic accuracy, Philpotts said. Lev Barinov, PhD, of Koios was also a co-author on the study.

Although the software is intended for use as an adjunct during radiologist interpretation, the researchers wanted to evaluate its theoretical benefit by retrospectively and independently assessing its potential impact, if any, on lesion management recommendations, Philpotts said.

"This type of analysis allows us to begin to set the bounds on the impact such systems will have on the interpretation of ultrasound studies," she said.

The researchers gathered cases from October 1, 2017, to September 30, 2018, of women with dense breasts that were interpreted as negative on digital breast tomosynthesis and who subsequently received whole-breast screening ultrasound. A total of 206 lesions of BI-RADS 3 or higher from 206 patients were included in the analysis. For the purposes of the study, ground truth was established via pathological results or an average of 15 months follow-up.

Of the 206 lesions, 162 were diagnosed as BI-RADS 3 (probably benign) by the radiologist and 44 were deemed to be BI-RADS 4 (suspicious). There were seven malignant lesions, two of which were classified by the original interpreting radiologist as BI-RADS 3 and five of which were categorized as BI-RADS 4. The remaining 109 lesions were benign. 

All identified lesions were anonymized and annotated with regions of interest by dedicated breast imagers in two orthogonal planes. The AI software then processed the two orthogonal B-mode views of each lesion to generate a likelihood of malignancy -- benign, probably benign, suspicious, and probably malignant -- that aligned to BI-RADS categories 2-5.

Each software assessment category can then be further subdivided by a confidence level indicator, which displays where within each risk category the lesion falls and provides a continuous probability of malignancy that can be used for subsequent data analysis, Philpotts noted.

Of the BI-RADS 3 lesions in the study that were actually benign, the AI software would have downgraded 41% to BI-RADS 2 and upgraded 32% to BI-RADS 4. The remaining 27% remained as BI-RADS 3. The software identified all malignant lesions, including the two lesions originally categorized as BI-RADS 3 by the initial interpreting radiologist.

Performance of AI software on assessing masses on screening breast ultrasound
	Radiologists	AI software
Sensitivity	71.4%	100%
Area under the curve	0.79	0.89

Larger and prospective studies will be needed, however, to assess how the software integrates into clinical workflow and influences patient management, according to Philpotts. 

She acknowledged the limitations of their study, including its use of only B-mode lesions. In addition, the group only examined the software's standalone output and didn't evaluate joint physician/AI decision-making.

"Additional clinical information, mammographic findings, or Doppler diagnostic evaluation would [also] be incorporated by radiologists when using the AI software in actual clinical practice," she said.

Hematocrit Sign

 

USPSTF advises against carotid artery stenosis screening

 

By Kate Madden Yee, AuntMinnie.com staff writer

February 2, 2021 -- The U.S. Preventive Services Task Force (USPSTF) is advising against screening for asymptomatic carotid artery stenosis in the general adult population in a final recommendation statement published February 2 in JAMA.

The recommendation is consistent with the task force's 2014 statement, which graded carotid artery stenosis screening a D. The reason for the low grade is that the harms of carotid artery screening outweigh the benefits, according to USPSTF member Dr. Michael Barry of Massachusetts General Hospital in Boston.

"The Task Force wants to help prevent people from having a stroke, but screening for coronary artery stenosis is not an effective way to do so," he said in a USPSTF statement. "Unfortunately, screening for coronary artery stenosis in adults without symptoms does more harm than good, and we continue to recommend against it."

Carotid artery stenosis affects extracranial carotid arteries, and asymptomatic carotid artery stenosis refers to stenosis in persons without a history of ischemic stroke, transient ischemic attack, or other neurologic symptoms referable to the carotid arteries, the task force wrote in the JAMA article. Screening for the disease is accomplished through a variety of imaging modalities, including carotid duplex ultrasonography, MRI angiography, and CT angiography.

But these screening exams just aren't effective, according to the task force.

"The USPSTF found no externally validated risk stratification tools that could reliably distinguish between asymptomatic persons who have clinically important carotid artery stenosis and persons who do not, or the risk of stroke related to carotid artery stenosis," it wrote.

In an editorial also published in JAMA on February 2, Dr. Larry Goldstein, a neurologist at the University of Kentucky in Lexington, lauded the USPSTF's position.

"The estimated population-attributable risk for stroke related to asymptomatic carotid artery stenosis is approximately 0.7%, a risk considerably lower than for other stroke risk factors such as hypertension, atrial fibrillation, cigarette smoking, and hyperlipidemia," Goldstein wrote. "There remains no validated risk stratification tool for identifying a subpopulation of adults with a prevalence of asymptomatic carotid artery stenosis with a higher population-attributable risk that would lead to a benefit of intervention beyond risk factor management.'

Others pushed back, suggesting that the task force did not include evidence of the benefits of screening in its evaluation process -- or consideration of risk factors that occur in almost a third of U.S. adults, such as high blood pressure, hyperlipidemia, diabetes, smoking, limited physical activity, and poor diet.

"Without a true randomized clinical trial to directly answer the question, there is a lack of consensus and clarity on the role of carotid ultrasonographic screening for prevention of stroke in individuals who are asymptomatic," wrote Dr. Rebecca Smith-Bindman of the University of California, San Francisco in a JAMA Network Open editorial. "Nearly all of the specialty societies actually agree with the USPSTF and recommend against screening with carotid ultrasonography. However, these strong statements against screenings are all followed by the list of exceptions of individuals who, based on risk factors or characteristics, should in fact be screened."

QT Ultrasound

 

UGAP và CAP định lượng gan thấm mỡ

 

UGAP measurements UGAP measurements were performed using a LOGIQ E10 ultrasound machine (GE Healthcare, Wauwatosa, WI, USA), using a C1-6-D convex array probe. All measurements were performed in fasting conditions for more than 4 hours, on patients in a supine position, with the right arm in maximum abduction, by intercostal approach, in the right liver lobe. A large colored-coded attenuation map, automatically adjusted by the system, was positioned in the right liver lobe, in a homogenous area of the liver, free of large vessels (fig1). Using the quality map option, the best image was selected in order to acquire the attenuation coefficient measurement. Ten measurements were performed using one or two selected images of the liver and the values were automatically stored in the system. Reliable UGAP measurements were defined as the median value of 10measurements performed in a homogeneous area of liver parenchyma, with an IQR/M <0.30. UGAP values are expressed in dB/cm/ MHz or in dB/m. LOGIQ E10 ultrasound machine can also perform liver stiffness measurements for fibrosis evaluation using an accurate 2D-Shear Wave Elastography (2D-SWE) technique [20-23], but this type of evaluation was not included in the present study.