Shear wave elastography (SWE) is an ultrasound-based stiffness quantification technology that is used for noninvasive liver fibrosis assessment. However, despite widescale clinical adoption, SWE is largely unused by preclinical researchers and drug developers for studies of liver disease progression in small animal models due to significant experimental, technical, and reproducibility challenges. Therefore, the aim of this work was to develop a tool designed specifically for assessing liver stiffness and echogenicity in small animals to better enable longitudinal preclinical studies. A highfrequency linear array transducer (12-24 MHz) was integrated into a robotic small animal ultrasound system (Vega; SonoVol, Inc., Durham, NC) to perform liver stiffness and echogenicity measurements in three dimensions. The instrument was validated with tissue-mimicking phantoms and a mouse model of nonalcoholic steatohepatitis. Female C57BL/6J mice (n = 40) were placed on choline-deficient, L-amino acid-defined, high-fat diet and imaged longitudinally for 15 weeks. A subset was sacrificed after each imaging timepoint (n = 5) for histological validation, and analyses of receiver operating characteristic (ROC) curves were performed. Results demonstrated that robotic measurements of echogenicity and stiffness were most strongly correlated with macrovesicular steatosis (R 2 = 0.891) and fibrosis (R 2 = 0.839), respectively. For diagnostic classification of fibrosis (Ishak score), areas under ROC (AUROCs) curves were 0.969 for ≥Ishak1, 0.984 for ≥Ishak2, 0.980 for ≥Ishak3, and 0.969 for ≥Ishak4. For classification of macrovesicular steatosis (S-score), AUROCs were 1.00 for ≥S2 and 0.997 for ≥S3. Average scanning and analysis time was <5 minutes/liver. Conclusion: Robotic SWE in small animals is feasible and sensitive to small changes in liver disease state, facilitating in vivo staging of rodent liver disease with minimal sonographic expertise. (Hepatology Communications 2022;6:1827-1839).U ltrasound-based shear wave elastography (SWE) is a revolutionary imaging technique that noninvasively measures the mechanical stiffness of biological tissue, such as liver, in vivo. (1) In SWE, a high-intensity ultrasonic pulse is used to generate transverse mechanical waves in the tissue (i.e.,
The incidence of pulmonary fungal infections is very low in Uruguay, and such infections typically affect immunocompromised patients. We report the case of an immunocompetent patient presenting with a two-month history of cough, dyspnea, and fever. The patient resided in a rural area. Imaging tests revealed extensive pneumonitis and pulmonary fibrosis. On the basis of direct mycological examination, culture, and serological testing, we made a diagnosis of concomitant histoplasmosis and paracoccidioidomycosis. The patient presented arterial hypotension that was diagnostic of adrenocortical insufficiency. Although the pulmonary fibrosis and pneumonia were irreversible, the clinical condition of the patient improved after antifungal treatment. This was an exceptional case of two pulmonary fungal infections occurring simultaneously in the same patient.Keywords: Paracoccidioidomycosis; Histoplasmosis; Lung diseases, fungal.
ResumenLa incidencia de las micosis pulmonares en Uruguay es muy baja, y estas usualmente aparecen en pacientes inmunocomprometidos. Se discute el caso de un paciente inmunocompetente proveniente de área rural, que presenta tos, disnea y fiebre de dos meses de evolución. La imagenología mostró una neumonitis extensa y fibrosis pulmonar. Los test micológicos directos, cultivo y serológicos muestran histoplasmosis y paraccocidioidomicosis en forma concomitante. El paciente presentó hipotensión arterial diagnosticándose una insuficiencia suprarrenal. A pesar de que la extensa fibrosis pulmonar y la neumonitis no fueron reversibles, el paciente mejoró clínicamente con el tratamiento antifúngico. Se trata de un caso excepcional de dos micosis pulmonares en un mismo paciente.
Sonoelastography is an ultrasonic technique that provides qualitative and quantitative images of tissue elasticity. Even though the Kasai variance estimator is a key part of the sonoelastographic image formation, there are no studies that demonstrate that its performance using discrete time signals and finite sized ensemble lengths is optimal. In this work, the influence of the selection of acquisition parameters (pulse repetition frequency or PRF, vibration frequency, and ensemble length) on the quality of the elastograms is studied. Simulations are carried out to define the optimal PRF and ensemble length given a vibration frequency in order to avoid artifacts which can severely degrade image quality. This empirical criterion is supported by sonoelastography experiments performed using two commercial scanners, where the variability increased from 4% to 42% at the worst selection of acquisition parameters. Although a further mathematical proof of the empirical findings is required, these results suggest that careful selection of PRF, vibration frequency and ensemble lengths is required to ensure unbiased sonoelastograms.
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