Editing Medical ultrasound (section)

=== {{anchor|Pulmonology (lungs)}}Pulmonology (lungs) ===
Ultrasound is used to assess the [[lung]]s in a variety of settings including critical care, emergency medicine, trauma surgery, as well as general medicine. This imaging modality is used at the bedside or examination table to evaluate a number of different lung abnormalities as well as to guide procedures such as [[thoracentesis]], (drainage of pleural fluid (effusion)), needle aspiration biopsy, and [[catheter]] placement.<ref>{{Cite web|url=https://www.uptodate.com/contents/bedside-pleural-ultrasonography-equipment-technique-and-the-identification-of-pleural-effusion-and-pneumothorax|title=UpToDate|website=www.uptodate.com|access-date=2019-07-23}}</ref> Although air present in the lungs does not allow good penetration of ultrasound waves, interpretation of specific artifacts created on the lung surface can be used to detect abnormalities.<ref>{{Cite web|url=https://lus.mstech.eu|title=Lung Ultrasound Simulator|access-date=2021-09-30}}</ref>

==== Lung ultrasound basics ====
* '''The Normal Lung Surface:''' The lung surface is composed of visceral and parietal [[Pulmonary pleurae|pleura]]. These two surfaces are typically pushed together and make up the pleural line, which is the basis of lung (or pleural) ultrasound. This line is visible less than a centimeter below the rib line in most adults. On ultrasound, it is visualized as a [[Echogenicity|hyperechoic]] (bright white) horizontal line if the ultrasound probe is applied perpendicularly to the skin.
* '''Artifacts:''' Lung ultrasound relies on artifacts, which would otherwise be considered a hindrance in imaging. Air blocks the ultrasound beam and thus visualizing healthy lung tissue itself with this mode of imaging is not practical. Consequently, physicians and sonographers have learned to recognize patterns that ultrasound beams create when imaging healthy versus diseased lung tissue. Three commonly seen and utilized artifacts in lung ultrasound include lung sliding, A-lines, and B-lines.<ref name=":0">{{Cite book|title=Lung Ultrasound in the Critically Ill: The BLUE Protocol|last=Lichtenstein|first=Daniel|publisher=Springer|year=2016|isbn=978-3-319-15370-4}}</ref>
** §&nbsp; '''Lung Sliding:''' The presence of lung sliding, which indicates the shimmering of the pleural line that occurs with movement of the visceral and parietal pleura against one another with respiration (sometimes described as 'ants marching'), is the most important finding in normal aerated lung.<ref name=":1">{{cite journal |last1=Husain |first1=LubnaF |last2=Hagopian |first2=Laura |last3=Wayman |first3=Derek |last4=Baker |first4=WilliamE |last5=Carmody |first5=KristinA |title=Sonographic diagnosis of pneumothorax |journal=Journal of Emergencies, Trauma, and Shock |date=2012 |volume=5 |issue=1 |pages=76–81 |doi=10.4103/0974-2700.93116 |pmid=22416161 |pmc=3299161 |doi-access=free }}</ref> Lung sliding indicates both that the lung is present at the chest wall and that the lung is functioning.<ref name=":0" />
** §&nbsp; '''A-lines:''' When the ultrasound beam makes contact with the [[Pulmonary pleurae|pleural line]], it is reflected back creating a bright white horizontal line. The subsequent reverberation artifacts that appear as equally spaced horizontal lines deep to the pleura are A-lines. Ultimately, A-lines are a reflection of the ultrasound beam from the pleura with the space between A-lines corresponding to the distance between the parietal pleura and the skin surface.<ref name=":0" /> A-lines indicate the presence of air, which means that these artifacts can be present in normal healthy lung (and also in patients with pneumothorax).<ref name=":1" />
** §&nbsp; '''B-lines:''' B-lines are also reverberation artifacts. They are visualized as [[Echogenicity|hyperechoic]] vertical lines extending from the pleura to the edge of the ultrasound screen. These lines are sharply defined and laser-like and typically do not fade as they progress down the screen.<ref name=":0" /> A few B-lines that move along with the sliding pleura can be seen in normal lung due to acoustic impedance differences between water and air. However, excessive B-lines (three or more) are abnormal and are typically indicative of underlying lung pathology.<ref name=":1" />

==== Lung pathology assessed with ultrasound ====
* '''[[Pulmonary edema]]''': Lung ultrasound has been shown to be very sensitive for the detection of pulmonary edema. It allows for improvement in diagnosis and management of critically ill patients, particularly when used in combination with echocardiography. The sonographic feature that is present in pulmonary edema is multiple B-lines. B-lines can occur in a healthy lung; however, the presence of 3 or more in the anterior or lateral lung regions is always abnormal. In pulmonary edema, B-lines indicate an increase in the amount of water contained in the lungs outside of the pulmonary vasculature. B-lines can also be present in a number of other conditions including pneumonia, pulmonary contusion, and lung infarction.<ref>{{Cite journal|last1=Blanco|first1=Pablo A.|last2=Cianciulli|first2=Tomás F.|date=2016|title=Pulmonary Edema Assessed by Ultrasound: Impact in Cardiology and Intensive Care Practice|journal=Echocardiography|language=en|volume=33|issue=5|pages=778–787|doi=10.1111/echo.13182|pmid=26841270|s2cid=37476194}}</ref> Additionally, it is important to note that there are multiple types of interactions between the pleural surface and the ultrasound wave that can generate artifacts with some similarity to B-lines but which do not have pathologic significance.<ref>{{cite journal |last1=Soldati |first1=Gino |last2=Demi |first2=Marcello |title=The use of lung ultrasound images for the differential diagnosis of pulmonary and cardiac interstitial pathology |journal=Journal of Ultrasound |date=June 2017 |volume=20 |issue=2 |pages=91–96 |doi=10.1007/s40477-017-0244-7 |pmid=28592998 |pmc=5440336 }}</ref>
* '''[[Pneumothorax]]''': In clinical settings when pneumothorax is suspected, lung ultrasound can aid in diagnosis.<ref>{{cite journal |last1=Volpicelli |first1=Giovanni |last2=Elbarbary |first2=Mahmoud |last3=Blaivas |first3=Michael |last4=Lichtenstein |first4=Daniel A. |last5=Mathis |first5=Gebhard |last6=Kirkpatrick |first6=Andrew W. |last7=Melniker |first7=Lawrence |last8=Gargani |first8=Luna |last9=Noble |first9=Vicki E. |last10=Via |first10=Gabriele |last11=Dean |first11=Anthony |last12=Tsung |first12=James W. |last13=Soldati |first13=Gino |last14=Copetti |first14=Roberto |last15=Bouhemad |first15=Belaid |last16=Reissig |first16=Angelika |last17=Agricola |first17=Eustachio |last18=Rouby |first18=Jean-Jacques |last19=Arbelot |first19=Charlotte |last20=Liteplo |first20=Andrew |last21=Sargsyan |first21=Ashot |last22=Silva |first22=Fernando |last23=Hoppmann |first23=Richard |last24=Breitkreutz |first24=Raoul |last25=Seibel |first25=Armin |last26=Neri |first26=Luca |last27=Storti |first27=Enrico |last28=Petrovic |first28=Tomislav |title=International evidence-based recommendations for point-of-care lung ultrasound |journal=Intensive Care Medicine |date=April 2012 |volume=38 |issue=4 |pages=577–591 |doi=10.1007/s00134-012-2513-4 |pmid=22392031 |doi-access=free }}</ref> In pneumothorax, air is present between the two layers of the pleura and lung sliding on ultrasound is therefore absent. The [[Positive and negative predictive values|negative predictive value]] for lung sliding on ultrasound is reported as 99.2–100%&nbsp;– briefly, if lung sliding is present, a pneumothorax is effectively ruled out.<ref name=":1" /> The absence of lung sliding, however, is not necessarily specific for pneumothorax as there are other conditions that also cause this finding including [[acute respiratory distress syndrome]], [[Pulmonary consolidation|lung consolidations]], pleural adhesions, and [[pulmonary fibrosis]].<ref name=":1" />
* '''[[Pleural effusion]]''': Lung ultrasound is a cost-effective, safe, and non-invasive imaging method that can aid in the prompt visualization and diagnosis of pleural effusions. Effusions can be diagnosed by a combination of physical exam, percussion, and [[auscultation]] of the chest. However, these exam techniques can be complicated by a variety of factors including the presence of [[mechanical ventilation]], obesity, or patient positioning, all of which reduce the sensitivity of the physical exam. Consequently, lung ultrasound can be an additional tool to augment plain [[Chest radiograph|chest Xray]] and [[CT scan|chest CT]].<ref name=":2">{{cite journal |last1=Brogi |first1=E. |last2=Gargani |first2=L. |last3=Bignami |first3=E. |last4=Barbariol |first4=F. |last5=Marra |first5=A. |last6=Forfori |first6=F. |last7=Vetrugno |first7=L. |title=Thoracic ultrasound for pleural effusion in the intensive care unit: a narrative review from diagnosis to treatment |journal=Critical Care |date=December 2017 |volume=21 |issue=1 |page=325 |doi=10.1186/s13054-017-1897-5 |pmid=29282107 |pmc=5745967 |doi-access=free }}</ref> Pleural effusions on ultrasound appear as structural images within the thorax rather than an artifact. They will typically have four distinct borders including the pleural line, two rib shadows, and a deep border.<ref name=":0" /> In critically ill patients with pleural effusion, ultrasound may guide procedures including needle insertion, [[thoracentesis]], and [[Chest tube|chest-tube insertion]].<ref name=":2" />
* '''[[Lung cancer]] staging:''' In [[pulmonology]], endobronchial ultrasound (EBUS) probes are applied to standard flexible endoscopic probes and used by pulmonologists to allow for direct visualization of endobronchial lesions and lymph nodes prior to transbronchial needle aspiration.  Among its many uses, EBUS aids in lung cancer staging by allowing for lymph node sampling without the need for major surgery.<ref>{{cite journal |doi=10.1136/thx.2005.047829 |title=Real-time endobronchial ultrasound guided transbronchial needle aspiration for sampling mediastinal lymph nodes |year=2006 |last1=Herth |first1=F J F |last2=Eberhardt |first2=R |last3=Vilmann |first3=P |last4=Krasnik |first4=M |last5=Ernst |first5=A |journal=Thorax |volume=61 |issue=9 |pages=795–8 |pmid=16738038 |pmc=2117082}}</ref>
* '''[[COVID-19]]''': Lung ultrasound has proved useful in the diagnosis of COVID-19 especially in cases where other investigations are not available.<ref>{{cite journal |last1=Lesser |first1=FD |last2=Smallwood |first2=N |last3=Dachsel |first3=M |title=Point-of-care lung ultrasound during and after the COVID-19 pandemic |journal=Ultrasound |date=1 August 2021 |volume=29 |issue=3 |pages=140 |pmid=34567225|  doi=10.1177/1742271X211033737| pmc=8366220 |s2cid=236980540 |doi-access=free }}</ref><ref>{{cite journal |last1=Knight |first1=T. |last2=Parulekar |first2=P. |last3=Rudge |first3=G. |last4=Lesser |first4=F. |last5=Dachsel |first5=M. |last6=Aujayeb |first6=A. |last7=Lasserson |first7=D. |last8=Smallwood |first8=N. |title=S68 National COVID point of care lung ultrasound evaluation (society for acute medicine with the intensive care society) |journal=Thorax |date=1 November 2021 |volume=76 |issue=Suppl 2 |pages=A44–A45 |doi=10.1136/thorax-2021-BTSabstracts.74|s2cid=243885812 |doi-access=free }}</ref><ref>{{cite journal |last1=Lesser |first1=FD |last2=Dachsel |first2=M |last3=Smallwood |first3=N |title=The Diagnostic Accuracy and Prognostic Value of Lung ultrasound in Suspected COVID-19 a retrospective service evaluation. |journal=Acute Medicine |date=2022 |volume=21 |issue=1 |pages=56–58 |doi=10.52964/AMJA.0895 |pmid=35342913|s2cid=247762623 |doi-access=free }}</ref>