Quantitative Lung Ultrasound Comet Measurement: Method and Initial Clinical Results

Abstract

Background/Aims: Recently, ultrasound signals termed ‘lung water comets' associated with pulmonary edema have been correlated with adverse clinical events in dialysis patients. These comets fluctuate substantially during the ultrasound exam highlighting the need for objective quantitative measurement methods. Methods: We developed an image-processing algorithm for the detection and quantification of lung comets. Quantification measures included comet number (comet count) and the fraction of the ultrasound beams with comet findings (comet fraction). We used this algorithm in a pilot study in 20 stable dialysis outpatients to identify associations between ultrasound comets and clinical parameters including blood pressure (BP), percent blood volume reduction on dialysis (%BV), ejection fraction (EF), and ultrafiltration on dialysis (UF). Results: Positive findings included associations with lung comet measurements with pre-dialysis Diastolic BP (r = 0.534, p = 0.015), subject age (r = -0.446, p = 0.049), and a combination of EF and end dialysis %BV reduction (r = -0.585, p = 0.028). Comet fraction and comet count were closely correlated due to the inherent relationship between these two metrics (r = 0.973, p < 0.001). Negative findings included ultrasound comets that did not change from beginning to end of dialysis (p = 0.756), and were not significantly correlated with single dialysis treatment UF (p = 0.522), subject body weight (p = 0.208), or BMI (p = 0.358). Conclusions: Ultrasound signal processing methods may help quantify lung ultrasound comets. Additional findings include algorithmic lung comet measurement that did not change significantly during single dialysis sessions in these stable outpatients, but were associated with cardiovascular and fluid status parameters.

Influence of Scan Duration on Pulmonary Capillary Hemorrhage Induced by Diagnostic Ultrasound

“…PCH areas on the lung surface were measured as before, but were considered inadequate to fully describe the PCH impact. The severity of some pulmonary conditions may be indicated by the length of the comets (Gargani et al 2009; Weitzel et al 2015). Also, the number of CTAs (also called “B lines”) appears to have a correlation with the extent of parenchymal changes in CT images (Martelius et al 2016).…”

Comparison between clinical judgment and integrated lung and inferior vena cava ultrasonography for dry weight estimation in hemodialysis patients

“…Underlying diffuse pulmonary parenchymal disease can result in artifacts that are not clearly discernible from B‐lines, making this method less reliable . Subcutaneous emphysema, soft tissue swelling and obesity can also hinder LUS . Poor visualization of IVC can pose difficulty in using this method.…”

Effects of Volume Overload and Current Techniques for the Assessment of Fluid Status in Patients with Renal Disease

“…These acoustic reverberations will be identified visually as B-lines (formerly known as "lung comets" [69]), which are the equivalent of B-lines (Kerley B-lines) detected by chest X-rays [70]. The extent of pulmonary congestion can be assessed by the number and strength of these comets [6,15,[71][72][73]. Although in ESRD the relationship between EVLW, as assessed by LUS, and different markers of volume status is still uncertain [74], there is a clear relationship between EVLW and different adverse outcomes in this population.…”