Objectives
- Know the basic terminology to describe ultrasound images: echogenicity, planes of imaging, four cardinal probe movements
- Understand the various ultrasound probe types (phased array, curvilinear, linear) and uses for each probe
- Describe the approach to performing lung ultrasound; identify the anatomic landmarks (ribs, pleural line, liver, spine)
- Describe the interpretation and appearance of normal lung: lung sliding, A-lines, ‘Seashore’ sign on M-mode
- Describe the interpretation and appearance of pneumothorax: no lung sliding, ‘Barcode’ sign on M-mode
- Describe the interpretation and appearance of B-lines on lung ultrasound; name disease states that cause B-lines
Lecture (presented by Hani Kuttab, MD)
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Name the four descriptions of echogenicity, and structures/causes for each
Four key descriptions of echogenicity:
- Hyperechoic (bright reflection): bones, gallstones
- Isoechoic (similar in appearance to surrounding structures): liver, spleen
- Hypoechoic (darker in appearance to surrounding structures): hematoma
- Anechoic (dark, no reflection): bladder
Name the three ultrasound probe types, general frequencies, and what each would be used for
The three probes:
- Phased Array (cardiac probe): lower frequency probe (1-5 MHz), good for cardiac, abdominal views
- Linear: high frequency probe (7.5 MHz), good for superficial structures (soft tissue, tendon, ocular ultrasound)
- Curvilinear (abdominal probe): middle/lower frequency (2-5 MHz), good for abdominal structures, deep lung
Describe the interpretation and appearance of lung sliding, A-lines, and B-lines.
Lung sliding: visualization of the visceral (attached to lung) and parietal (attached to chest wall) pleura sliding over one another
A-lines (artifact lines): horizontal reflections/copy of the pleural line
B-lines: some type of material within the interstitial space and/or the alveoli (e.g., water, pus, scarring, etc.)
What is the typical approach and appearance to evaluating for pleural effusion?
Ultrasound probe/indicator aimed up towards the patient’s head, in the mid-axillary line, fanning slightly towards the spine
In normal lungs, the space above the diaphragm cannot be visualized (obscured by the normal lung tissue)
In abnormal lungs (e.g., pneumonia, atelectasis, pleural effusion), the spine is visualized above the diaphragm (spine sign)
Name various disease states which may give the appearance of B-lines on lung ultrasound.
Focal B-lines (localized to one lung zone):
- Atelectasis
- Pulmonary contusion (trauma)
- Lobar pneumonia
Diffuse B-lines
- Cardiogenic pulmonary edema
- Pulmonary fibrosis
- ARDS
- Viral syndrome/pneumonia (COVID-19)
What is the appearance of normal lung and a pneumothorax when visualized using M-mode?
Normal Lung under M-mode: ‘Seashore’ sign.
Pneumothorax under M-mode: ‘Barcode’ or ‘Stratosphere’ sign.
What is the most specific finding for a pneumothorax on ultrasound?
Visualization of the ‘lung point’– the point where normal lung sliding joints the start of the pneumothorax.