Renal transplant ultrasound: assessment of complications and advanced applications.

Renal transplantation is the most commonly performed solid organ transplant procedure. Monitoring renal transplants with ultrasound is a critical component in the management of transplant patients both in the immediate aftermath of surgery and longitudinally. Many complications are detectable via ultrasound evaluation with relative prevalence dependent on the time since surgery.

Residual Ultrasound-Enhancing Agents Mimicking Portal Venous Gas.

Sonographic detection of mobile echogenic foci within the main portal vein and its branches or within the liver parenchyma extending along the portal triads to the periphery of the liver is an alarming finding that has been associated with portal venous gas in the setting of bowel ischemia. Ultrasound-enhancing agents (UEAs) have been widely utilized in abdominal ultrasound for evaluation of organ neoplasms and vascular patency as well as in echocardiography for the evaluation of cardiac function. The appearance of UEAs on abdominal ultrasound can resemble gas like that seen in the portal venous system and liver in patients with bowel ischemia; therefore, UEA residuals should always be a part of the differential diagnosis of echogenic foci when seen on abdominal ultrasounds with preceding recent UEA administration.

Coordinate-Independent 3-D Ultrasound Principal Stretch and Direction Imaging.

Objective: In clinical ultrasound, current 2-D strain imaging faces challenges in quantifying three orthogonal normal strain components. This requires separate image acquisitions based on the pixel-dependent cardiac coordinate system, leading to additional computations and estimation discrepancies due to probe orientation. Most systems lack shear strain information, as displaying all components is challenging to interpret.

Multi-Task Learning for Motion Analysis and Segmentation in 3D Echocardiography.

Characterizing left ventricular deformation and strain using 3D+time echocardiography provides useful insights into cardiac function and can be used to detect and localize myocardial injury. To achieve this, it is imperative to obtain accurate motion estimates of the left ventricle. In many strain analysis pipelines, this step is often accompanied by a separate segmentation step; however, recent works have shown both tasks to be highly related and can be complementary when optimized jointly.

Delayed cancer diagnosis in the pregnant patient: navigating a complex medical and ethical dilemma.

Prompt diagnosis of cancer in pregnancy is necessary to ensure timely management and improve outcomes. However, there are a several reasons why diagnosis may be delayed in pregnancy. Three major contributors to delayed diagnosis and treatment are patient delay, provider delay, and referral delay.

Thyroid cancer in pregnancy: diagnosis, management, and treatment.

The evaluation and management of cancer during pregnancy requires special care to assure the health and safety of both the mother and fetus. The diagnosis and treatment of thyroid cancer in the non-pregnant patient often involves radioactive iodine exposure. However, radioactive iodine is contraindicated in pregnancy and surgical interventions pose risks to both the mother and fetus.

Melanoma in pregnancy.

Melanoma is one of the most common types of cancer diagnosed during pregnancy. Patients with advanced disease require frequent staging examinations (e.g.

Co-attention spatial transformer network for unsupervised motion tracking and cardiac strain analysis in 3D echocardiography.

Myocardial ischemia/infarction causes wall-motion abnormalities in the left ventricle. Therefore, reliable motion estimation and strain analysis using 3D+time echocardiography for localization and characterization of myocardial injury is valuable for early detection and targeted interventions. Previous unsupervised cardiac motion tracking methods rely on heavily-weighted regularization functions to smooth out the noisy displacement fields in echocardiography.

Simultaneous Segmentation and Motion Estimation of Left Ventricular Myocardium in 3D Echocardiography Using Multi-task Learning.

Motion estimation and segmentation are both critical steps in identifying and assessing myocardial dysfunction, but are traditionally treated as unique tasks and solved as separate steps. However, many motion estimation techniques rely on accurate segmentations. It has been demonstrated in the computer vision and medical image analysis literature that both these tasks may be mutually beneficial when solved simultaneously.

Diagnostic Accuracy of Shear-Wave Elastography for Breast Lesion Characterization in Women: A Systematic Review and Meta-Analysis.

Purpose: The aim of this study was to assess the diagnostic accuracy of 2-D shear-wave elastography (SWE) for differentiating benign and malignant breast lesions in women with abnormal findings on mammography.

Methods: Included in this review are studies of diagnostic accuracy published before June 2021 using 2-D SWE to evaluate female breast lesions. Included studies were required to include at least 50 lesions, report quantitative shear-wave speed (SWS) thresholds, and include a reference standard of either biopsy or 2-year stability.

Multi-frame Attention Network for Left Ventricle Segmentation in 3D Echocardiography.

Echocardiography is one of the main imaging modalities used to assess the cardiovascular health of patients. Among the many analyses performed on echocardiography, segmentation of left ventricle is crucial to quantify the clinical measurements like ejection fraction. However, segmentation of left ventricle in 3D echocardiography remains a challenging and tedious task.

Wunderlich Syndrome: Wonder What It Is.

Wunderlich syndrome (WS) refers to spontaneous renal or perinephric hemorrhage occurring in the absence of known trauma. WS is much less common than hemorrhage occurring after iatrogenic or traumatic conditions. Lenk's triad of acute onset flank pain, flank mass, and hypovolemic shock is a classic presentation of WS but seen in less than a quarter of patients.

Synthesis of fracture radiographs with deep neural networks.

Purpose: We describe a machine learning system for converting diagrams of fractures into realistic X-ray images. We further present a method for iterative, human-guided refinement of the generated images and show that the resulting synthetic images can be used during training to increase the accuracy of deep classifiers on clinically meaningful subsets of fracture X-rays.

Methods: A neural network was trained to reconstruct images from programmatically created line drawings of those images.

Endoscopic Retrograde Cholangiopancreatography: Deciphering the Black and White.

Endoscopic Retrograde Cholangiopancreatography (ERCP) remains the conventional method of imaging the pancreatic and biliary tree and is performed by direct injection of iodinated contrast material via the major papilla. This diagnostic procedure gained popularity in the 1970s and subsequently paved way for ERCP guided interventions such as sphincterotomy, stone retrieval and stent placement. Currently, therapeutic ERCP is more widespread than diagnostic ERCP primarily due to the availability of noninvasive imaging.

Measurement of Liver Stiffness Using Shear Wave Elastography in a Rat Model: Factors Impacting Stiffness Measurement with Multiple- and Single-Tracking-Location Techniques.

The clinical use of elastography for monitoring fibrosis progression is challenged by the subtle changes in liver stiffness associated with early-stage fibrosis and the comparatively large variance in stiffness estimates provided by elastography. Single-tracking-location (STL) shear wave elasticity imaging (SWEI) is an ultrasound elastography technique previously found to provide improved estimate precision compared with multiple-tracking-location (MTL) SWEI. Because of the improved precision, it is reasonable to expect that STL-SWEI would provide improved ability to differentiate liver fibrosis stage compared with MTL-SWEI.

Shear wave arrival time estimates correlate with local speckle pattern.

We present simulation and phantom studies demonstrating a strong correlation between errors in shear wave arrival time estimates and the lateral position of the local speckle pattern in targets with fully developed speckle. We hypothesize that the observed arrival time variations are largely due to the underlying speckle pattern, and call the effect speckle bias. Arrival time estimation is a key step in quantitative shear wave elastography, performed by tracking tissue motion via cross-correlation of RF ultrasound echoes or similar methods.

Scholte wave generation during single tracking location shear wave elasticity imaging of engineered tissues.

The physical environment of engineered tissues can influence cellular functions that are important for tissue regeneration. Thus, there is a critical need for noninvasive technologies capable of monitoring mechanical properties of engineered tissues during fabrication and development. This work investigates the feasibility of using single tracking location shear wave elasticity imaging (STL-SWEI) for quantifying the shear moduli of tissue-mimicking phantoms and engineered tissues in tissue engineering environments.

Single tracking location acoustic radiation force impulse viscoelasticity estimation (STL-VE): A method for measuring tissue viscoelastic parameters.

Single tracking location (STL) shear wave elasticity imaging (SWEI) is a method for detecting elastic differences between tissues. It has the advantage of intrinsic speckle bias suppression compared with multiple tracking location variants of SWEI. However, the assumption of a linear model leads to an overestimation of the shear modulus in viscoelastic media.

Minimization of displacement estimation bias due to high amplitude-reflections using envelope-weighted normalization.

In elastography, displacement estimation is often performed using cross-correlation-based techniques, assuming fully-developed, homogeneous speckle. In the presence of a local, large variation in echo amplitude, such as a reflection from a vessel wall, this assumption does not hold true, resulting in a biased displacement estimate. Normalizing the echo by its envelope before displacement estimation reduces this effect at the cost of larger jitter errors.