The dawn of Diagnostic Ultrasound and Recent Advance of Breast Ultrasound

The diagnostic application of ultraso- und has been developing very rapidly in the world and has became indispensable diagnostic modality in every field of clin- ical medicine. At the same time, remark- able development has been achieved in China and the exellent results were highly     

Can Therapeutic Ultrasound Influence the Integration of Skin Grafts?

Therapeutic ultrasound (TUS) is a widely used coadjuvant physical means to promote biological tissue repair. In the present investigation, the influence of TUS on the integration of full-thickness skin graft was studied in rabbits. Twenty female adult rabbits were used and two 2x2-cm square full-thickness skin grafts were obtained from both scapular regions and swapped, the one cut out on the right being placed on the left and vice versa. The graft on the right was irradiated with TUS (3 MHz, 0.5 W/cm2, 5-min duration) once a day for seven consecutive days, beginning on the third postoperative day; the graft on the left was submitted to simulated irradiation. The animals were killed on the 11th day and the grafted areas were resected (graft+safety margin) for histological examination. Five-mum-thick sections were alternatively stained with Gomori's trichrome, proliferating cell nuclear antigen (PCNA) and picrosirius red and examined under the light microscope, and the epidermal and dermal areas were measured and proliferating cells and new blood vessels counted. The results showed a significant increase (p=0.007) in the number of proliferating epidermal cells (12.18% and 7.34% of the total number of cells in the irradiated and control grafts, respectively) and new blood vessels per field (p=0.0001) in the irradiated grafts (6.27 compared with 3.07). Despite the increased number of proliferating cells and blood vessels, there was no significant difference between the epidermis (246,392 microm2 and 200,626 microm2 in groups 1 and 2, respectively; p=0.07) and dermis (2,157,730 microm2 and 2,109,150 microm2 in groups 1 and 2, respectively; p=0.21) areas as a function of thickness for both groups. We conclude that TUS induces morphological alterations in biological processes, such as epidermic germinative layer cell proliferation and neoangiogenesis, which are involved in the integration of full-thickness skin grafts. This has a potential for clinical use in humans.     

Diagnosis of Complex Pulley Ruptures Using Ultrasound in Cadaver Models

Pulley ruptures are common in climbing athletes. The purposes of this study were to determine the specific positioning of each pulley with regards to the joint, and to evaluate the ultrasound diagnostics of various pulley rupture combinations. For this, 34 cadaver fingers were analyzed via ultrasound, the results of which were compared to anatomic measurements. Different pulley ruptures were then simulated and evaluated using ultrasound in standardized dynamic forced flexion. Visualization of the A2 and A4 pulleys was achieved 100% of the time, while the A3 pulley was visible in 74% of cases. Similarly, injuries to the A2 and A4 pulleys were readily observable, while A3 pulley injuries were more challenging to identify (sensitivity of 0.2 for singular A3 pulley, 0.5 for A2/A4 pulley and 0.33 for A3/A4 pulley ruptures). Receiver operating characteristic analysis was used to evaluate the optimal tendon-bone distance for pulley rupture diagnosis, a threshold which was determined to be 1.9 mm for A2 pulley ruptures and 1.85 for A4 pulley ruptures. This study was the first to carry out a cadaver ultrasound examination of a wide variety of pulley ruptures. Ultrasound is a highly accurate tool for visualizing the A2 and A4 pulleys in a cadaver model. This method of pathology diagnosis was determined to be suitable for injuries to the A2 and A4 pulleys, but inadequate for A3 pulley injuries.     

Noninvasive Transcranial Stimulation of Rat Abducens Nerve by Focused Ultrasound

Nonpharmacologic and nonsurgical transcranial modulation of the nerve function may provide new opportunities in evaluation and treatment of cranial nerve diseases. This study investigates the possibility of using low-intensity transcranial focused ultrasound (FUS) to selectively stimulate the rat abducens nerve located above the base of the skull. FUS (frequencies of 350 kHz and 650 kHz) operating in a pulsed mode was applied to the abducens nerve of Sprague-Dawley rats under stereotactic guidance. The abductive eyeball movement ipsilateral to the side of sonication was observed at 350 kHz, using the 0.36-msec tone burst duration (TBD), 1.5-kHz pulse repetition frequency (PRF), and the overall sonication duration of 200 msec. Histologic and behavioral monitoring showed no signs of disruption in the blood brain barrier (BBB), as well as no damage to the nerves and adjacent brain tissue resulting from the sonication. As a novel functional neuro-modulatory modality, the pulsed application of FUS has potential for diagnostic and therapeutic applications in diseases of the peripheral nervous system.     

The Impact of Different Lung Ultrasound Protocols in the Assessment of Lung Lesions in COVID-19 Patients: Is There an Ideal Lung Ultrasound Protocol?

BackgroundIn the past months, several lung ultrasonography (LUS) protocols have been proposed, mainly on previously validated schemes independent of coronavirus disease 2019 (COVID-19).ObjectivesThe main purpose of this study was to determine the impact and accuracy of different LUS protocols proposed in COVID-19.MethodsPatients were evaluated with a standard sequence of LUS scans in 72 intercostal spaces along 14 anatomic lines in the chest. A scoring system of LUS findings was reported and then analyzed separately according to each proposed LUS protocol zones. This score was then correlated to a validated Pulmonary Inflammation Index (PII) on chest Computed Tomography (CT).ResultsThirty-two patients were enrolled. The most frequent pattern was ground-glass opacities in the chest X-ray (53.1%), chest CT (59.1%) and subpleural or lobar consolidations (40.8%) in the posteroinferior areas (p < 0.001) on LUS. The Interclass Correlation Coefficient (ICC) was significantly correlated with almost every protocol analyzed except the 8-zone (p = 0.119) and the 10-zone protocol that only included one posterior point (p = 0.052). The highest ICC was obtained with a 12-zone protocol (ICC 0.500; p = 0.027) and decreased as more points were included.ConclusionsIn conclusion, our study results suggest that performing an ultrasound protocol with 12-zone scanning, including the superior and inferior areas of the anterior, lateral and posterior regions of the chest was consistent with higher ICC and higher degree of concordance with CT. We emphasize the need of a more standardization technique to further implement and develop this imaging modality in COVID-19.     

Ultrasound imaging of forearm fractures in children: a viable alternative?

OBJECTIVE: A pilot study to investigate whether ultrasonography can be reliably used to demonstrate uncomplicated greenstick and torus fractures in children. METHOD: Children between the ages of 2 and 14 years with a high clinical suspicion of a non-articular, undisplaced forearm fracture were included. Ultrasound imaging of the injury was performed by a consultant radiologist who gave an immediate report. Standard radiographs of the forearm were then obtained and the patient treated in the normal way. The radiograph was formally reported on at a later date. RESULTS: 26 patients were included. There was an absolute correlation between the ultrasound and radiographic findings. The procedure was well tolerated. CONCLUSION: Ultrasound seems effective for detecting uncomplicated forearm fractures in children. The procedure is easy to perform and the images easy to interpret. A larger study will now be undertaken to confirm these initial findings.     

Ultrasound imaging of forearm fractures in children: a viable alternative?

Objective—A pilot study to investigate whether ultrasonography can be reliably used to demonstrate uncomplicated greenstick and torus fractures in children.

Method—Children between the ages of 2 and 14 years with a high clinical suspicion of a non-articular, undisplaced forearm fracture were included. Ultrasound imaging of the injury was performed by a consultant radiologist who gave an immediate report. Standard radiographs of the forearm were then obtained and the patient treated in the normal way. The radiograph was formally reported on at a later date.

Results—26 patients were included. There was an absolute correlation between the ultrasound and radiographic findings. The procedure was well tolerated.

Conclusion—Ultrasound seems effective for detecting uncomplicated forearm fractures in children. The procedure is easy to perform and the images easy to interpret. A larger study will now be undertaken to confirm these initial findings.

     

Localized Disruption of Blood Albumin–Phenytoin Binding Using Transcranial Focused Ultrasound

Plasma protein binding (PPB) plays an important role in drug pharmacokinetics, particularly for central nervous system drugs, as PPB affects the blood concentration of unbound drug available to cross the blood–brain barrier (BBB). We report the non-invasive, spatially specific disruption of PPB to phenytoin, an anti-epileptic drug with high affinity to albumin, using 250-kHz focused ultrasound (FUS) delivered in a pulsed manner (55-ms tone burst duration, 4-Hz pulse repetitions). Equilibrium dialysis performed on sonicated phosphate-buffered saline solution containing phenytoin and bovine serum albumin revealed a 27.7% elevation in the unbound phenytoin concentration compared with an unsonicated control. Sonication of a unilateral brain hemisphere in rats (n = 10) after intraperitoneal phenytoin injection revealed increased parenchymal phenytoin uptake compared with the unsonicated hemisphere, without evidence of temperature change or BBB disruption. These findings illustrate the use of FUS as a novel technique for spatially selective disruption of PPB, which may be applied to a wide range of drug–plasma protein interactions.     

What Do Clinical Users Know Regarding Safety of Ultrasound During Pregnancy?

OBJECTIVE: The main goal of this study was to determine end users' knowledge regarding safety aspects of diagnostic ultrasound during pregnancy. End users' attitudes toward the use of ultrasound in low-risk pregnancies were also assessed. METHODS: A questionnaire was distributed to ultrasound end users attending review courses and hospital grand rounds between April and June 2006. RESULTS: One hundred thirty end users completed the questionnaires (63% response rate). Sixty-three percent were physicians (n=84), most of them obstetricians (81.7%). About 18% of participants routinely performed Doppler ultrasound examinations during the first trimester. Fifty percent of end users thought that the number of ultrasound examinations in low-risk pregnancy should be limited to 1 to 3 (mean +/- SD, 2.6 +/- 0.9). Almost 70% disapprouved of "keepsake/entertainment" ultrasound. Although 32.2% of the participants were familiar with the term thermal index, only 17.7% actually gave the correct answer to the question on the nature of the thermal index. About 22% were familiar with the term mechanical index, but only 3.8% described it properly. Almost 80% of end users did not know where to find the acoustic indices. Only 20.8% were aware that they are displayed on the sonographic monitor during the examinations. End users with higher knowledge of safety issues thought that there should be limitations on the number of ultrasound examinations in low-risk pregnancies (odds ratio, 3.3; 95% confidence interval, 1.1-10.0; P=.028). Likewise, these end users were more likely to respond that ultrasound might have adverse effects during pregnancy (odds ratio, 3.2; 95% confidence interval, 1.1-12.5; P=.045). CONCLUSIONS: Ultrasound end users are poorly informed regarding safety issues during pregnancy. Further efforts in the realm of education and training are needed to improve end user knowledge about the acoustic output of the machines and safety issues.     

Can Ultrasound Propagate in the Joint Space of a Human Knee?

A large body of evidence supports the principle that the use of low-intensity pulsed ultrasound with a frequency of 1.5 MHz can reduce fracture healing time. It is hypothesized that similar therapeutic benefits may be achieved in damaged articular cartilage. This study looks specifically at a 22-mm circular ultrasound transducer delivering ultrasound with a frequency of 1.5 MHz. A human cadaver knee was imaged using CT, the resulting images were used to help map a number of hydrophone positions in the joint from which measurements were taken. The experimental results suggest that at best there is a 30-mm window in which to place the ultrasound transducer for ultrasound to propagate through the joint space. In terms of a clinical device delivering an I(SATA) of 30 mW cm(-2) to anterior regions of the joint, the I(SATA) in posterior regions will at best be in the region of 10 mW cm(-2). The clinical implications of this are not known and require further investigation.     

Point-of-Care Ultrasound—A New Option for Early Quantitative Assessment of Pulmonary Edema

The aim of the work described here was to investigate the value of point-of-care ultrasound (POCUS) in the early assessment of the severity of pulmonary edema in rabbits. A rabbit oleic acid (OA)-induced pulmonary edema model was used. Thirty-two New Zealand rabbits were randomly divided into four groups: a control group and three pulmonary edema groups (mild, moderate and severe). Features of transthoracic B-line artifacts (BLA), blood pH, PaO₂ and PaCO₂, serum inflammatory factors, lung coefficient (LC), lung wet-to-dry weight ratio (W/D) and lung histopathology were assessed. BLA features and severity of pulmonary edema were semiquantitatively scored. Correlations between the number of BLA and PaO₂, PaCO₂, serum inflammatory factors, LC and W/D were analyzed. An additional 8 rabbits with severe pulmonary edema were used as the verified group, in which the lung was divided into ex vivo BLA (BLA-ev)-free (BLA-ev-free) and BLA-ev-clustered subregions depending on the features of BLA-ev recorded by ex vivo lung ultrasound. Lung specimens from each subregion were collected for histopathological examination. Relationships between features of BLA-ev and lung histopathological abnormalities were analyzed. With increasing doses of OA, number of BLA, W/D and levels of serum inflammatory factors decreased. Meanwhile, lung pathologic abnormalities were aggravated. In addition, time of appearance of BLA, blood pH and PaO_2, and PaCO₂ decreased dose dependently on OA (p < 0.05). Number of BLA was linear positively correlated with severity of pulmonary edema (r = 0.953, p < 0.05). Consistently, the features of BLA-ev reflected the severity of lung histopathological abnormalities (r = 0.936, p < 0.05). Thus, POCUS is useful in the early quantitative assessment of the severity of pulmonary edema.     

Ultrasound findings of papillary thyroid microcarcinoma: a review of 113 consecutive cases with histopathologic correlation

Papillary thyroid microcarcinoma (PTMC) is a malignant thyroid tumor of less than 1 cm in size. Ultrasound (US) is the preferred imaging modality for PTMC. This study retrospectively evaluated the US results from 113 consecutive cases of PTMC with 127 nodules and correlated the results with the histopathologic findings. The results showed none of the PTMC nodules had a cystic element. Half of the PTMC nodules had a well-defined boundary and the remaining half had an ill-defined boundary. A percent (6.3%) of the nodules had a halo sign. Microcalcification was present in approximately half of the PTMC nodules. The cancerous tissue with a papillary structure was hypoechogenic and the amount of fibrous stroma determined whether the nodule echogenicity was heterogeneous or homogeneous. Heterogeneous echogenicity was associated with a fibrous stroma proportion of >20%. Only PTMC nodules with predominantly follicular structures containing a large proportion of colloid demonstrated isoechogenicity. Well-defined boundaries on US were associated with well-defined histologic margins, with or without the presence of an intact fibrous pseudo-capsule. A halo sign with a well-defined boundary detected by US was associated with the presence of an intact fibrous pseudo-capsule. Half of the PTMC nodules with ill-defined boundaries exhibited infiltration into the surrounding thyroid tissue, while the remaining half of the PTMC nodules with ill-defined boundaries on US presented irregular nodule margins by histology, rather than nodule infiltration. Psammoma bodies detected at a frequency ≥5 per ×200 microscopic field of view were detectable on US as microcalcifications.     

Size Measurement of Tissue Debris Particles Generated from Pulsed Ultrasound Cavitational Therapy – Histotripsy

Extensive mechanical tissue fractionation can be achieved using successive high intensity ultrasound pulses (“histotripsy”). Histotripsy has many potential medical applications where noninvasive tissue removal is desired (e.g., tumor ablation). There is a concern that debris generated by histotripsy-induced tissue fractionation might be an embolization hazard. The aim of this study is to measure the size distribution of these tissue debris particles. Histotripsy pulses were produced by a 513-element 1 MHz array transducer, an 18-element 750 kHz array transducer and a 788 kHz single element transducer. Peak negative pressures of 11 to 25 MPa, pulse durations of 3 to 50 cycles, pulse repetition frequencies of 100 Hz to 2 kHz were used. Tissue debris particles created by histotripsy were collected and measured with a particle sizing system. In the resulting samples, debris <6 μm in diameter constituted >99% of the total number of tissue particles. The largest particle generated by one of the parameter sets tested was 54 μm in diameter, which is smaller than the clinic filter size (100 μm) used to prevent embolization. The largest particles generated using other parameter sets were larger than 60 μm but the value could not be specified using our current setup. Exposures with shorter pulses produced lower percentages of large tissue debris (>30 μm) in comparison to longer pulses. These results suggest that the tissue debris particle size distribution is adjustable by altering acoustic parameters if necessary. (E-mail: zhenx@umich.edu)     

Point-of-Care Ultrasound–Guided Percutaneous Cannulation of Extracorporeal Membrane Oxygenation: Make it Simple

Background

Cannulation of the great vessels is required for extracorporeal membrane oxygenation (ECMO). Currently, there is no guideline for optimal imaging modalities during percutaneous cannulation of ECMO.

How to Perform Intra-Operative Contrast-Enhanced Ultrasound of the Brain—A WFUMB Position Paper

Intra-operative ultrasound has become a relevant imaging modality in neurosurgical procedures. While B-mode, with its intrinsic limitations, is still considered the primary ultrasound modality, intra-operative contrast-enhanced ultrasound (ioCEUS) has more recently emerged as a powerful tool in neurosurgery. Though still not used on a large scale, ioCEUS has proven its utility in defining tumor boundaries, identifying lesion vascular supply and mapping neurovascular architecture. Here we propose a step-by-step procedure for performing ioCEUS analysis of the brain, highlighting its neurosurgical applications. Moreover, we provide practical advice on the use of ultrasound contrast agents and review technical ultrasound parameters influencing ioCEUS imaging.     

Ultrasound study of adenopathies within the hepatoduodenal ligament: The “rosebud” pattern

In about 10% of lymphopathies with extensive retroperitoneal adenopathies, adenopathies are also encountered within the hepatoduodenal ligament. When large, such adenopathies, which surround the portal vein, hepatic artery, and bile duct, give rise to a particular ultrasound pattern: the rosebud pattern.