Ultrasound Vector Flow Imaging for AVF Fistula.

Ultrasound  Vector Flow Imaging  for AVF Fistula

ABSTRACT
Introduction: We report the use of a new ultrasound technique to evaluate the axial and lateral components of a complex flow in the arteriovenous fistula (AVF). Vector Flow Imaging (VFI) allows to identify different components of the flow in every direction, even orthogonal to the flow streamline, represented by many single vectors. VFI could help to identify flow alterations in AVF, probably responsible for its malfunction.
Methods: From February to June 2016, 14 consecutive patients with upper-limb AVF were examined with a Resona 7 (Mindray, Shenzhen, China) ultrasound scanner equipped with VFI. An analysis of mean velocity, angular direction and mean number of vectors impacting the vessel wall was carried out. We also identified main flow patterns present in the arterial side, into the venous aneurysm and in correspondence of significant stenosis.
Results: A disturbed flow with the presence of vectors directed against the vessel walls was found in 9/14 patients(64.28%): in correspondence of the iuxta-anastomotic venous side (4/9; 44.4%), into the venous aneurysmal tracts (3/9; 33.3%) and in concomitance of stenosis (2/9;22.2%). The mean velocity of the vectors was around 20-25 cm/s, except in presence of stenosis, where the velocities were much higher (45-50 cm/s). The vectors directed against the vessel walls presented high angle attack (from 45° to 90°, with a median angular deviation 65°).
Conclusions: VFI was confirmed to be an innovative and intuitive imaging technology to study the flow complex-
ity in the arteriovenous fistulas.
Keywords: Arteriovenous fistula, Hemodialysis, Hemodynamic shear stress, Ultrasound, Vascular access, Vector
Flow Imaging.

Tongue Ultrasound may identify Obstructive Sleep Apnea

By Theresa Pablos, AuntMinnie staff writer

May 21, 2020 -- Tongue stiffness measured by shear-wave elastography (SWE) ultrasound may be able to help identify patients with obstructive sleep apnea (OSA) while they're awake, according to the findings of a pilot study published on May 10 in Ultrasound in Medicine & Biology.

Some studies have suggested that up to 38% of the population in Europe and the U.S. can have OSA, but many patients with the potentially fatal condition go undiagnosed. Ultrasound may be one easily accessible and noninvasive tool to help identify patients who may benefit from a sleep test.

"We hypothesized that development of OSA involves changes in tongue stiffness, and this effect can be seen using SWE during wakefulness," wrote the authors, led by Dr. Chun-Hsiang Chang from Cardinal Tien Hospital and the Fu Jen Catholic University School of Medicine in New Taipei City, Taiwan.

To test their hypothesis, Chang and colleagues recruited 46 participants, 26 of whom had sleep-confirmed OSA and 20 healthy controls.

First, the researchers performed conventional B-mode ultrasound using a curvilinear-array transducer to identify the tongue tissues of the patients. Then, they performed SWE while the participants breathed normally and when they performed Müller's maneuver, a technique in which they attempt to inhale while forcing their mouth and nostrils closed.

Patients with sleep apnea showed significant differences from the healthy controls in multiple tongue stiffness values while breathing normally and during Müller's maneuver. Those with OSA also had significantly higher values during Müller's maneuver than when breathing normally for the anterior and middle thirds of the tongue. For comparison, controls had no significant differences for any part of the tongue.

The differences remained statistically significant predictors of OSA after the authors adjusted for age, sex, BMI, and neck circumference, middle tongue shear modulus measured during normal breathing, and whole and posterior tongue and geniohyoid muscle shear modulus measured during Müller's maneuver.

"Quantifying tongue tissue stiffness in a clinical setting is difficult," the authors wrote. "Through [ultrasound] SWE, we found that the stiffness of the tongue was higher in awake OSA patients than in healthy controls during normal breathing and the [Müller's maneuver]."

Based on their findings, the authors recommended cut-off shear-wave modulus values to help detect patients with obstructive sleep apnea. For some values, the accuracy could exceed 80%. The authors cautioned, however, that the findings are preliminary and that more research is needed to validate the results.

"Future application of the technique may involve ultrasonographic measurement of tongue stiffness during sedative or natural sleep, which will help to define the pathophysiology for an individual patient with OSA and to verify treatment results for those procedures targeting the tongue," the authors wrote.

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Müller's manoeuvre is a procedure used in medicine to diagnose sleep apnea, some types of tinnitus,^[1] and other medical problems.

Procedure

After a forced expiration, an attempt at inspiration is made with closed mouth and nose, whereby the negative pressure in the chest and lungs is made very subatmospheric; the reverse of a Valsalva maneuver.

This technique is designed to look for collapsed sections of airways such as the trachea and upper airways. In this maneuver, the patient attempts to inhale with his mouth closed and his nostrils plugged, which leads to a collapse of the airway. Introducing a flexible fiberoptic scope into the hypopharynx to obtain a view, the examiner may witness the collapse and identify weakened sections of the airway. Müller's maneuver is used to help determine the cause of sleep apnea. A positive test result means the site of upper airway obstruction is likely below the level of the soft palate, and the patient will probably not benefit from a uvulopalatopharyngoplasty alone. This maneuver is very helpful in doing MRI for sleep apnea, when sedation to patient can be avoided.

There is some evidence that the sites of obstruction with Müller's maneuver do not represent reliably the sites of obstruction during normal sleep. Other factors such as the body's position whilst conducting the manoeuvre may well affect this.

Müller's maneuver can also be used to terminate supraventricular tachycardia in an acute primary care setting.

ULTRASOUND for LUNG COVID-19

Course teaches ob/gyns to identify COVID-19 on lung US.

By Theresa Pablos, AuntMinnie staff writer

May 4, 2020 -- A two-and-a-half-hour online course boosted the knowledge of COVID-19 lung ultrasound presentation among ob/gyn clinicians with no prior lung ultrasound experience, according to the findings of a small study published on April 29 in Ultrasound in Obstetrics & Gynaecology.

....

Lung ultrasound scans have proved to be an effective, noninvasive modality for screening patients, including pregnant patients, with confirmed or suspected cases of the novel coronavirus. The latest study adds to existing research demonstrating ob/gyn clinicians may be well-poised to recognize B-lines, subpleural consolidations, a thickened or patchy pleural line, and other hallmark signs of potential infection with the novel coronavirus.

For their study, Buonsenso and Moro recruited two pneumologists and one pediatrician, each with more than 10 years of lung ultrasound experience, to create an online training module.

The module begins with a 15-minute pretest that includes 10 ultrasound video clips showing healthy, normal lungs or ones with pathological patterns. The test asks participants to choose whether the lung video shows the following:

a) Normal findings

b) Clear and distinct vertical artifacts with small pleural alterations

c) Broken pleural line and small consolidations

d) White lung without evidence subpleural consolidations

e) White lung with evidence subpleural consolidations

f) Pattern not compatible, vast consolidations

g) Pattern not compatible, pleural effusions

Following the pretest, participants watch a two-hour theoretical course providing lung ultrasound education. Finally, the course ends with a 15-minute test showing the same 10 ultrasound clips.

.....

Adherence to the Standards for Reporting of Diagnostic Accuracy (STARD) 2015 Guidelines in Acute Point-of-Care Ultrasound Research.

Abstract

IMPORTANCE Incomplete reporting of diagnostic accuracy research impairs assessment of risk of bias and limits generalizability. Point-of-care ultrasound has become an important diagnostic tool for acute care physicians, but studies assessing its use are of varying methodological quality.

OBJECTIVE To assess adherence to the Standards for Reporting of Diagnostic Accuracy (STARD) 2015 guidelines in the literature on acute care point-of-care ultrasound.

EVIDENCE REVIEW MEDLINE was searched to identify diagnostic accuracy studies assessing point-of-care ultrasound published in critical care, emergency medicine, or anesthesia journals from 2016 to 2019. Studies were evaluated for adherence to the STARD 2015 guidelines, with the following variables analyzed: journal, country, STARD citation, STARD-adopting journal, impact factor, patient population, use of supplemental material, and body region. Data analysis was performed in November 2019.

SIÊU ÂM CƠ VÂN LY GIẢI [DO CHẤN THƯƠNG]

Sonographic appearance of rhabdomyolysis – a systematic review of the literature 

Łukasz Sein Anand, Wojciech Kosiak

Abstract 

Rhabdomyolysis is the process of striated muscle cell lysis, during which proteins and microelements such as myoglobin are released into the bloodstream. It is important to diagnose rhabdomyolysis as soon as possible and start the treatment according to severity, as it is a state that significantly increases the mortality of the patients. The current gold standard of rhabdomyolysis diagnosis is the creatine kinase plasma concentration test, but it can be also diagnosed with imaging techniques, such as ultrasound (US). This review aims to gather previously published information regarding sonographic appearance of rhabdomyolysis. We searched through PubMed and ScienceDirect databases for studies using designed queries. After the selection process we were left with 13 studies containing a description of US appearance of rhabdomyolysis confirmed with a CK plasma level test. Findings described in the majority of the cases were muscle thickening, ground glass opacity, traits of edema and anechoic areas. Other than these, there were several less often reported findings. As a conclusion, rhabdomyolysis seems to have its own US appearance, but for now it cannot be precisely specified and needs further research for clarification.

Keywords: ultrasonography; rhabdomyolysis; point-of-care

Rhabdomyolysis seems to have its own US appearance, mostly in a form of muscle thickening, ground glass opacity, traits of edema, anechoic areas and various less often reported lesions. Due to the small number of published cases the typical aspect of rhabdomyolysis is not clear and needs further research for clarification.

FDA relaxes rules on ultrasound in COVID-19

The FDA carved out a special section of the guidance for ultrasound systems, which have become useful in diagnosing patients with COVID-19. The agency said that because ultrasound scanners do not emit ionizing radiation, the FDA believes users can have "additional flexibility," with modifications allowed under the following circumstances:

• Modifications that would allow an ultrasound scanner to be used outside of the environment for which it is cleared, such as a general practitioner's office or a field hospital
• Changes that would enable the acquisition of images by healthcare practitioners who are not trained in sonography, under appropriate supervision
• The addition of lung scanning clinical applications, as long as labeling is included that is based on established practice guidelines, such as from the American Institute of Ultrasound in Medicine (AIUM)
• The availability of probes and machine settings that are suitable for lung scanning, such as probes at a frequency of 3 MHz and higher, and with linear, curvilinear, and phased-array technologies
• The use of a mechanical index (MI) < 1.4 as an indicator for potential biological effects on tissues containing gas bodies

The agency would frown on ultrasound modifications as follows:

• Changes that would result in an increase of the derated maximum acoustic output parameters
• Modifications that would exceed known safety limits in humans, such as a MI ≥ 1.4 for lung images
• Modifications that would allow lay users to acquire images without guidance of healthcare practitioners.

Abdominal Pain: An Unusual -- But Not Rare -- COVID-19 Presentation

• Whitney J. Palmer

April 20, 2020

Fever. Cough. Shortness of breath. These are what have become known as the classic, tell-tale COVID-19 symptoms. But, there’s a different, less common, one that should alert you to possible infection– abdominal discomfort.

Recent literature has revealed that as many as 20 percent of patients present to the hospital with a digestive symptom, such as diarrhea, vomiting, pain, accompanying their respiratory symptoms. And, roughly 5 percent show up with an abdominal complaint alone.
This is where abdominal radiologists can play an integral role, said industry experts in a recent article published in the American Journal of Roentgenology. A team, led by Abraham Dachman, M.D., professor of radiology and abdominal imaging specialist with UChicago Medicine, shared three cases where patients were referred for abdominal imaging and providers distinguished findings indicative of COVID-19 infection in the lung base.

“It’s important not to be lulled into a false sense of security by a chief complaint of abdominal pain,” Dachman wrote. “The fact that we observed several patients presenting in this way in such a short time period suggests that although abdominal symptoms are an unusual presentation of the infection, they are not rare, and abdominal radiologists must be on the lookout to diagnose COVID-19, even when it is not suspected clinically.”

Because these findings first appeared on abdominal scans, Dachman wrote, it’s important for all radiological sub-specialties to be aware that COVID-19 can produce abdominal complaints.

“Careful evaluation of the lung bases for the typical nodular, peripherally distributed ground-glass opacities may lead to the correct diagnosis before progressive respiratory manifestations,” he wrote. “An early diagnosis is helpful not only in patient care, but also in allowing healthcare workers to be prepared with the appropriate personal protective equipment.”