Objectives
Contrast‐enhanced diagnostic ultrasound (US) has a potential to induce localized biological effects. The potential for contrast‐enhanced diagnostic US bioeffects in liver were researched, ...with guidance from a report by Yang et al (Ultrasonics 2012; 52:1065–1071).
Methods
Contact and standoff scanning was performed for 10 minutes with a diagnostic US phased array at 1.6 MHz during bolus injection or infusion of a contrast agent at a high dose. The impact of the imaging on rat liver was investigated by measuring enzyme release, microvascular leakage, and staining of injured hepatocytes.
Results
The results showed liver enzyme release at 30 minutes, indicating liver injury, and elevated extraction of Evans blue dye, indicating microvascular leakage. In addition, Evans blue and trypan blue vital‐staining methods revealed scattered stained cells within the US scan plane. For the Evans blue method, fluorescent cell counts in frozen sections were greatest for standoff exposure with contrast infusion. The count decreased strongly with depth for bolus injection, which was probably reflective of the high attenuation noted for this agent delivery method.
Conclusions
The results qualitatively confirmed the report by Yang et al and additionally showed hepatocyte vital staining. Research is needed to determine the threshold for the effects and the contrast agent dose response.
Contrast-enhanced diagnostic ultrasound (CEDUS) can lead to microvascular injury and petechial hemorrhage by the cavitational mechanism of ultrasonic bioeffects. Capillary hemorrhage has been noted ...in the heart and kidney, which are common targets of CEDUS examination. CEDUS has also become useful for monitoring intestinal inflammation. In the 1990s, the risk of intestinal microvascular hemorrhage was investigated both for incidental exposure by lithotripter shockwaves and for contrast agent microbubbles acting as cavitation nuclei with laboratory pulsed ultrasound systems. This study was initiated to update the risk assessment for intestine exposed to diagnostic imaging simulating CEDUS. The abdomens of anesthetized rats were scanned by a 1.6 MHz phased array probe during infusion of microbubble suspensions simulating Definity ultrasound contrast agent. Dual image frames were triggered intermittently, and the output power was varied to assess the exposure response. Petechiae counts in small intestine mucosa and muscle layers increased with increasing trigger interval from 2 s to 10 s, indicative of a slow refill after microbubble destruction. The counts increased with increasing output above a threshold of 1.4 MPa peak rarefactional pressure amplitude. Petechiae were also seen in Peyer's patches, and occult blood was detected in many affected segments of intestine. These results are consistent with early laboratory pulsed-ultrasound results.
Sepsis is a high mortality condition characterized by multi-organ dysfunction. Sepsis-induced cardiomyopathy (SIC) refers to cardiac dysfunction in sepsis.
Our goal was to determine whether SIC can ...be detected in the emergency department (ED) using focused cardiac ultrasound (FCU).
A retrospective analysis of adults presenting to a single ED with sepsis over a 21-month period was performed. Patients were included if they met clinical sepsis criteria, received an FCU by an emergency physician in the ED, and a baseline echocardiogram performed in the previous 12 months. SIC was defined as a significant decrease in estimated left ventricular ejection fraction (LVEF) by FCU relative to baseline. Demographic and outcome characteristics were compared between three cohorts: patients with normal baseline LVEF and no decrease on presentation, patients with decreased LVEF and no significant change, and those with a significant decrease in LVEF from their normal baseline (SIC).
There were 110 patients that met inclusion criteria: 89 patients (81%) in the normal LVEF group, 12 (11%) in the prior decreased LVEF group, and 9 (8%) in the SIC group. Unadjusted mortality at 90 days for patients with SIC (67%) and prior decreased LVEF (58%) was significantly higher than those with normal EF (29%) (p = 0.019). When adjusted for age, gender, Charlson Index score, and lactate > 4.0 mmol/L, SIC was associated with mortality at 90 days (odds ratio 6.1, 95% confidence interval 1.37–32.92).
SIC can be detected using FCU by emergency physicians in the ED and is associated with increased 90-day mortality.
The purpose of our study was to evaluate the diagnostic accuracy of the ultrasound-guided attenuation parameter (UGAP) for the detection of hepatic steatosis in comparison with the controlled ...attenuation parameter (CAP), using histopathology as the reference standard. We prospectively analyzed 163 consecutive chronic liver disease patients who underwent UGAP, CAP, computed tomography and a liver biopsy on the same day between April 2016 and July 2017. Radiofrequency signals corresponding to the images were compensated by the reference signal previously measured from the uniform phantom with known attenuation (0.44 dB/cm/MHz). The attenuation coefficient was calculated from the signals' decay slope. The median attenuation coefficient values in patients with S0 (n = 62), S1 (n = 63), S2 (n = 23) and S3 grade (n = 15) were 0.485, 0.560, 0.660 and 0.720, respectively. Significant correlations were found between attenuation coefficient and percentage steatosis, CAP values and liver-to-spleen computed tomography attenuation ratio (p < 0.001). The areas under the receiver operating characteristic curve of UGAP for identifying ≥S1, ≥S2 and ≥S3 were 0.900, 0.953 and 0.959, respectively, which were significantly better than the results obtained with CAP for identifying ≥S2 and ≥S3. In conclusion, UGAP had high diagnostic accuracy for detecting hepatic steatosis in patients with chronic liver disease.
Recent research has found that contrast-enhanced diagnostic ultrasound (CEDUS) has the potential to induce localized injury in the liver, with clearly observable effects for contrast agent doses ...higher than the recommended dose and maximal mechanical index values. This study was undertaken to assess effects with intermittent exposure at lower contrast doses of infusion and at reduced output to determine thresholds. In addition, microbubble (MB) suspensions with enhanced content of larger MBs were tested. Exposure from a phased array probe (GE Vivid 7 Dimension, GE Vingmed Ultrasound, Horten, Norway) was applied at 1.6 MHz and 1-s intermittent frame trigger for 10 min with infusion of MB suspension with normal (1.8 µm), medium (3.1 µm) and large (5.3 µm) mean MB diameters. The bio-effect endpoint was the count of hepatocytes stained with Evans blue dye in frozen sections. For the normal MBs, the count increased for clinically relevant infusion dosages, but leveled off above 20 µL/kg/min. The evidence of injury declined with time from 30 min to 4 h and was lacking at 24 h. The exposure thresholds in terms of peak rarefactional pressure amplitude, divided by the square root of frequency (in situ mechanical index) were 1.7, 1.3 and 1.2 for the normal-, medium- and large-sized MB suspensions. The enhanced efficacy for larger MBs lends support to the two-criterion model for cavitational microvascular injury during CEDUS. Overall, CEDUS in liver appears to have markedly less potential for induction of tissue injury than has been reported in other tissues, which indicates a satisfactory safety profile for CEDUS using recommended parameters in normal liver.
•Dynamic ultrasound can reliably evaluate fibular translation in healthy controls.•It affords bilateral comparisons, which becomes critical as the amount of syndesmotic instability approaches greater ...degrees of subtlety.•Patient characteristics did not affect the amount of fibular translation.•Dynamic ultrasound is readily accessible at the point of care, at low cost, and with no ionizing radiation.•The dynamic assessment technique using ultrasound has potential to diagnose subtle syndesmotic instability.
Syndesmotic instability, when subtle, is challenging to diagnose and often requires visualization of the syndesmosis during applied stress. The primary aim was to assess normal distal tibiofibular motion in the sagittal plane using dynamic ultrasound under stress conditions. The secondary aim was to evaluate the reliability of dynamic stress ultrasonography.
Twenty-eight participants without history of ankle injury were included. Sagittal fibular translation was generated by applying a manual force to the fibula from anterior to posterior and from posterior to anterior. Distance between the ultrasound probe and the fibula was taken at two predefined points: 1) no force applied and, 2) during maximum force application. Each participant was scanned twice by two independent examiners, and each scan was analysed by two independent examiners. Three participants were scanned a second time by the same examiner who analysed these films twice to assess for intraobserver agreement. Means of exam 1 versus exam 2 were compared using a mixed linear model. Agreement among observers was calculated using intraclass correlation coefficients (ICC) interpreted as 0.4, poor; 0.4 〈 ICC < 0.59, acceptable; 0.6 < ICC < 0.74, good; ICC 〉 0.74, excellent.
Fifty-six ankles were included in the study, including 16 (57%) males and 12 (42%) females. Average anterior to posterior fibular sagittal translation was 0.89 ± 0.6 mm and posterior to anterior fibular sagittal translation was 0.49 ± 1.1 mm. Anterior to posterior translation means of exam 1 versus exam 2 showed no significant differences, means of 0.81 mm 0.7–0.9 versus 0.77 mm 0.7–1.0, and posterior to anterior means 95% CI of 0.42 mm 0.3–0.5 versus 0.44 mm 0.2–0.6 (p-values 0.416 and 0.758, respectively). Excellent Inter- and intraobserver agreement was found for all measurements taken.
Dynamic ultrasound allows one to effectively and readily evaluate sagittal translation of the distal tibiofibular joint. It is able to afford bilateral comparisons, which becomes critical as the amount of syndesmotic instability approaches greater degrees of subtlety.
Pulmonary capillary hemorrhage (PCH) can be induced by diagnostic ultrasound-a potential safety issue. Anesthetized rats were intubated for intermittent positive-pressure ventilation (IPPV) with 0 ...end-expiratory pressure, +4 cm H
O end-expiratory pressure (PEEP) and -4 cm H
O end-expiratory pressure (NEEP). Rats were imaged at 7.6 MHz with a Philips HDI 5000 ultrasound machine. The output was low (mechanical index MI = 0.22) for aiming and then was raised for 5 min in 20 different exposure groups with n = 8. Peak rarefactional pressure amplitudes were measured in water and de-rated for chest attenuation. The PCH areas were measured on the lung surface. At 2.2 MPa, PCH was 9.3 ± 6.6 mm
for IPPV, 1.6 ± 3.2 mm
for PEEP (p <0.001) and 26.8 ± 6.4 mm
for NEEP (p <0.001). Thresholds were 1.3 MPa for IPPV, 2.1 MPa for PEEP and 1.0 MPa for NEEP. The small ventilator pressures subtracted or added to trans-capillary stress generated by diagnostic ultrasound pulses, virtually eliminating PCH for PEEP but enhancing PCH for NEEP.
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