According to a review of the literature, narrow repetition artifacts are known as “comet-tail” ( 9) or “ring-down” ( 10) artifacts. The other is a roughly vertical narrow-based artifact spreading up to the edge of the screen. One type is a roughly horizontal repetition artifact.
In fact, two opposed types of artifacts can clearly be differentiated arising from the lung surface. On the other hand, ultrasound patterns of the aerated lung are not well known, and airy artifacts arising from the lung surface have not been extensively studied. Yet clinical experience and review of the literature show that lung ultrasound has been previously proposed for diagnosing pneumothorax ( 1-4) or alveolar consolidation ( 5-8). The lung is therefore usually considered poorly accessible to ultrasound. Can ultrasound, a noninvasive, easily implemented technique, be of any use? Basically, the problem is that air stops the progression of the ultrasound beam, and only reverberation artifacts are visible under the lung surface.
However, in critical care units, chest X-ray is performed at the bedside and technologic deficiencies may make this diagnosis difficult. The diagnosis of alveolar-interstitial syndrome is based on chest X-ray. In conclusion, presence of the comet-tail artifact allowed diagnosis of alveolar-interstitial syndrome. Tomodensitometric correlations showed that the thickened sub-pleural interlobular septa, as well as ground-glass areas, two lesions present in acute pulmonary edema, were associated with the presence of the comet-tail artifact. It was absent or confined to the last lateral intercostal space in 120 of 129 patients with normal chest X-ray (specificity of 93.0%). This pattern was present all over the lung surface in 86 of 92 patients with diffuse alveolar-interstitial syndrome (sensitivity of 93.4%). The ultrasonic feature of multiple comet-tail artifacts fanning out from the lung surface was investigated. The antero-lateral chest wall was examined using ultrasound. Ultrasound detection of the "comet-tail artifact" at the anterior chest wall allows complete pneumothorax to be discounted.Can ultrasound be of any help in the diagnosis of alveolar-interstitial syndrome? In a prospective study, we examined 250 consecutive patients in a medical intensive care unit: 121 patients with radiologic alveolar-interstitial syndrome (disseminated to the whole lung, n = 92 localized, n = 29) and 129 patients without radiologic evidence of alveolar-interstitial syndrome. Horizontal artifacts and absent lung sliding, when combined, had a sensitivity and a negative predictive value of 100% and a specificity of 96.5%. Horizontal artifacts had a sensitivity and a negative predictive value of 100% and a specificity of 60% for the diagnosis of pneumothorax. Ultrasound as well as computed tomography showed anterior consolidation or anterior pleural effusion in three cases. In the pneumothorax-free group, "comet-tail artifacts" were present in 87 cases and exclusive horizontal artifacts in 56. Ultrasound showed exclusive horizontal artifacts in all 41 analyzable cases of complete pneumothorax. The test was defined as positive for complete pneumothorax when only horizontal artifacts were visible, and negative when artifacts arising from the pleural line and spreading up to the edge of the screen (referred to as "comet-tail artifacts") were present.
#Comet tail artifact meaning portable
The anterior chest wall was investigated in supine patients using a portable device. We compared 41 complete pneumothoraces with 146 hemithoraces in 73 critically ill patients in which computed tomography showed absence of pneumothorax.
The medical ICU of a university-affiliated teaching hospital. The significance of these artifacts for the diagnosis of pneumothorax was assessed. Ultrasound artifacts arising from the lung-wall interface are either vertical (comet-tail artifacts) or horizontal.
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