The Association of American Medical Colleges (AAMC) has written an article about ultrasound education at the medical school level. In the current edition of their widely distributed publication The Reporter, they describe programs at the University of South Carolina School of Medicine, University of California (Irvine) School of Medicine, and the Mount Sinai School of Medicine.
The article notes,
With rapid advancements in ultrasound technology, such scenarios as this are becoming more commonplace, as a handful of the nation’s medical schools make ultrasound training a standard part of the curriculum. And there is a push to encourage more schools to use ultrasound.
Thoracic sonography is one of the most rapidly growing areas of emergency and critical care ultrasound. One very important emerging indication is to assess for lung consolidation. The characteristic appearance of consolidated lung is very sensitive and specific for pneumonia, but novices should heed some important pitfalls in making the diagnosis.
Special thanks to Jim Tsung, MD, MPH and Brittany Jones, MD for their tips, videos, and ongoing research in this important field! For further reading on this topic, please see this article.
Pitfall #1 – confusing thymus for a consolidation
Normal thymus in sagittal view:
Thymus (top half of screen) and heart (bottom right). Don’t confuse thymus for lung consolidation. Note there are no air bronchograms, but thymus has a faint speckled appearance.
Normal thymus in transverse view:
Thymus (top half of screen) and heart (bottom right). Don’t confuse thymus for lung consolidation. Note there are no air bronchograms, but thymus has a faint speckled appearance
Pneumonia adjacent to Thymus in transverse view:
Lung consolidation with air bronchograms (top left) adjacent to normal thymus (speckled appearance on top right) with heart (bottom right)
Pitfall #2 – mistaking spleen for consolidation.
This is an important pitfall for everyone to know about. The same issue applies to the liver & stomach. The sensitivity of lung US for pneumonia rises >90% if this mistake is avoided.
Left lower chest- sagittal view:
Be careful scanning the left lower chest (left anterior and left axillary line) – air in stomach and spleen may look like pneumonia if you don’t realize that you have scanned inferior to the diaphragm and past the end of the pleural line. Most common error by novices.
Left lower chest- transverse view:
Be careful scanning the left lower chest (left anterior and left axillary line) – air in stomach and spleen may look like pneumonia if you don’t realize that you have scanned inferior to the diaphragm and past the end of the pleural line.
Pitfall #3- missing pleural effusion
Here are a few examples to refresh your memory.
Left pleural effusion:
Identify:
Pleural effusion (anechoic wedge just beneath ribs and pleura)
Lung
Diaphragm
Spleen
Air in stomach
Do not confuse spleen and air in stomach for pneumonia.
This core didactic session recap is devoted to renal ultrasound. Point-of-care ultrasound uses focused clinical questions to guide management, and our didactic session use focused clinical questions to guide discussions of key literature.
Discussants Vincent Roddy and Phillip Andrus led our group through a series of questions which bring the relevance of renal sonography home.
1. Can the degree of hydronephrosis predict stone size?
In an word, yes. In a retrospective study of 177 patients with documented stones on CT scans, ultrasonographers blinded to the CT results were able to predict stone size (>5mm or <5mm) based on the degree of hydronephrosis observed (1).
Hydronephrosis was defined as mild, moderate, severe
Mild: Enlargement of calices with preservation of renal papillae
Moderate: Rounding of calices with obliteration of renal papillae
Severe: Caliceal ballooning with cortical thinning
Results:
Increasing degree of hydro associated with increasing proportion of ureteral calculi > 5mm (p < 0.001) Take-home points:
Stone size is an important predictor of stone passage and clinical outcome; < 5mm likely to pass regardless of location
Current guidelines recommend triage of “medical expulsion therapy” for calculi between 5 and 10 mm; > 10mm often require surgical removal
Ultrasound sensitivity for detection of stones greater than 5mm is poor. With severe hydro over one-third had stones over 5mm and one third of THAT group had caliculi larger than 10mm (2)
References:
Goertz JK, Lotterman S. Can the degree od hydronephrosis on US predict kidney stone size? Am J Emerg Med 2010; 28:813-6.
Preminger GM, Tiselius HG, Assimos DG, et al. 2007 guideline for the mgmt of ureteral calcul. J Urol 2007; 178:2418-34.
2. Should the bladder be included in the renal scan?
Yes – rapid ED renal ultrasound including images of the bladder might exclude distal obstruction and allows clinicians to focus on other diagnoses (1).
Ultrasound of the bladder also allows for the evaluation of the presence of “ureteral jets.” Although clinically utility is debatable, a unilaterally abnormal ureteral jet can be suggestive of high-grade obstruction on the ipsilateral body side. Ultrasound is useful in making this determination, though it is limited in its ability to determine stone location. It is important to note that normal ureteral jets cannot be used to exclude a diagnosis of renal colic. (2).
References:
Wakins S, Bowra J. Validation of EP Ultrasound in Diagnosing hydronephrosis in ureteric colic. Emergency Medicine Australasia (2007) 19, 188-195.
Sheafor D, Hertzberg B, et al. Nonenchanced Helical CT and US in the Emergency Evaluation of Patients with Renal Colic.
3. Can Emergency Physicians accurately diagnosis hydroneprhosis on bedside ultrasonography?
Yes, numerous studies have documented that ultrasound can accurately predict the degree of hydronephrosis as compared to that on CT scans (1-2) and that the degree of hydronephrosis is related to stone size (3).
References:
Gaspari RJ, Horst K. Emergency Ultrasound and urinalysis in the evaluation of flank pain. Acad Emer Med 2005; 12:1180-4.
Watkins S, Bowra J, Sharma P, Holdgate A, et el. Validation of EP ultrasound in diagnosing hydronephrosis in ureteric colic. Emerg Med Australas 2007; 19:188-95.
Goertz JK, Lotterman S. Can the degree od hydronephrosis on US predict kidney stone size? Am J Emerg Med 2010; 28:813-6.
In this post we’ll illustrate the optimal imaging angle for Doppler evaluation. Let’s start with basic Doppler physics.
Where to police officers situate themselves to aim a radar gun at speeding cars?
The maximal Doppler shift will be seen at 180 degrees. In fact at the instant the car passes the officer, (90 degrees) there will be zero Doppler shift. At that instant there is no movement between the object and the listener. So they aim the gun directly at the oncoming traffic, so the direction of their beam is parallel to the direction of [traffic] flow.
The image below illustrates Doppler shift of ultrasound reflected off a red blood cell:
Top: A normal ultrasound wave
Middle: Doppler shift reflected off the RBC moving toward the transducer (thus increasing the frequency of the returning wave)
Bottom: Doppler shift reflected off the RBC moving away from the transducer (thus decreasing the frequency of the returning wave).
Thanks to equipmentexplained.com for the image. Imaging at 180 degrees is impractical for diagnostic ultrasound, since the optimal B-mode imaging angle is 90 degrees. Therefore, most authorities recommend an imaging angle between 45-60 degrees for Doppler ultrasound imaging . If you are imaging a vascular structure at 90 degrees and getting no Doppler signal, try lowering your angle.
Is ultrasound the stethoscope of the future? Is it an extension of the physical examination? Will it replace the physical exam?
No.
Point-of-care ultrasound is a diagnostic test. It is a rapid, bedside, noninvasive, accurate, diagnostic test, but still a diagnostic test. It can certainly augment data obtained through physical examination and medical interviews, and adds to information obtained by blood assays and radiology studies.
It is performed using FDA-approved medical devices by clinicians with specialized training. Images used for medical decision-making may be archived and shared with colleagues from multiple specialties. Quality assurance programs improve clinician accuracy and accountability. These are not physical examination characteristics. These are qualities of good diagnostic tests.
There is and will continue to be debate about this issue. Whether we think about point-of-care ultrasound as a diagnostic test or part of the physical examination has ramifications for training, documentation, archiving, and billing.
We recommend checking the guidelines relevant to your specialty and making up your own mind on this issue. In either camp some things remain constant: train well and use ultrasound to enhance the care you provide your patients.
As a part of Ultrasound Awareness Month we’d like to let providers of all levels know about membership opportunities with national and international organizations.
They offer an enormous amount of information for providers at all levels; from the first time Sonographer to the Ultrasound Director and offer forums and support for all your Ultrasound-related endeavors.
Please visit the following websites for more information and/or follow them on twitter to interact with them in real time. We have included links to student, resident, or fellow membership options where applicable. Be sure to check out special rates, courses, and benefits in all of these organizations designed tom promote inclusion of providers at all levels!
Finding the right angle is critical to optimal imaging. In fact ‘right angle’ or perpendicular imaging is the best way to get a clear image. At 90 degrees, many more sound beams reflect back to the transducer than at more shallow angles.
In addition, the ultrasound energy is more spread out when it connects to the tissue at an angle, as seen above.
In this image of the kidney, notice the inferior aspect of the kidney (right arrow) is imaged at nearly 90 degrees. The white lines represent the plane of the kidney.
It has the sharpest border and is well-distinguished from the liver. The middle arrow represents the path of ultrasound energy hitting the the kidney off 90 degrees. Not a bad image but doesn’t look as good as the one imaged at 90 degrees. Finally, the left arrow represents the beam hitting the kidney almost parallel. Note that the kidney-liver interface looks fuzzy and there is a great loss of detail. Most of the ultrasound energy is reflecting off the surface AWAY from the transducer- hardly any is available to reflect back towards the transducer and yield a good image.
Thus, angling the probe 90 degrees to the structure you want to image can increase resolution and improve your image quality.
The Association of American Medical Colleges (AAMC) has written an article about ultrasound education at the medical school level. In the current edition of their widely distributed publication The Reporter, they describe programs at the University of South Carolina School of Medicine, University of California (Irvine) School of Medicine, and the Mount Sinai School of Medicine.
