High-resolution ultrasound-aided biophotonic imaging

Optical contrast is sensitive to functional parameters, including the oxygen saturation and total concentration of hemoglobin, in biological tissues. However, due to the overwhelming scattering encountered by light in tissues, traditional optical modalities cannot provide satisfactory spatial resolution beyond the ballistic (a few hundred microns) and quasiballistic (1-2 mm) regimes. Photoacoustic tomography is based on the high optical contrast yet utilizing the high ultrasonic resolution. Our work in this emerging area of research will be summarized in this invited talk. In this technology, a diffraction-based inverse-source problem is solved in the image reconstruction, for which we developed the rigorous reconstruction theory. We implemented a prototype and accomplished noninvasive transdermal and transcranial functional imaging of small-animal brains in vivo. Change in the cerebral blood oxygenation of a rat, as a result of the alternation from hyperoxia to hypoxia, was imaged successfully

The Diagnostic Accuracy of High Resolution Ultrasound Imaging for Detection of Secondary Hyperparathyroidism in Patients with Chronic Renal Failure

Ultrasound is one of the preferred modalities for evaluation of the parathyroid glands. This study was undertaken to determine the accuracy of high resolution ultrasound for secondary hyperparathyroidism in patients with chronic renal failure. From March 2008 to March 2009, ninety-one hemodialysis patients were examined by high resolution ultrasound (14 MHz) of the parathyroid glands in comparison to parathyroid hormone level. 43.9% of patients showed enlarged parathyroid glands with an average of 8.7 mm. The mean parathyroid hormone level of patients with enlarged parathyroid glands on sonography was 503 ± 450 pg/ml. We observed a significant correlation between parathyroid hormone level and enlarged parathyroid glands (P<0.0001). Sensitivity and specificity of sonography for detection of secondary hyperparathyroidism were 62.5% and 85.7% respectively. In conclusion, our study showed that high resolution sonography is a useful noninvasive method for the evaluation of secondary hyperparathyroidism in patients on hemodialysis and that sonographically enlarged glands may be a measure of severity of secondary hyperparathyroidism

Ultrasound in the diagnosis of a median neuropathy in the forearm: case report

<p>Abstract</p> <p>Background</p> <p>Electrodiagnostic studies are traditionally used in the diagnosis of focal neuropathies, however they lack anatomical information regarding the nerve and its surrounding structures. The purpose of this case is to show that high-resolution ultrasound used as an adjunct to electrodiagnostic studies may complement this lack of information and give insight to the cause.</p> <p>Case presentation</p> <p>A 60-year-old male patient sustained a forearm traction injury resulting in progressive weakness and functional loss in the first three digits of the right hand. High-resolution ultrasound showed the presence of an enlarged nerve and a homogenous soft-tissue structure appearing to engulf the nerve. The contralateral side was normal. Surgery revealed fibrotic bands emanating from the flexor digitorum profundus muscle compressing the median nerve thus confirming the ultrasound findings.</p> <p>Conclusion</p> <p>A diagnostically challenging case of median neuropathy in the forearm is presented in which high-resolution ultrasound was valuable in establishing an anatomic etiology and directing appropriate management.</p

High-resolution ultrasound of spigelian and groin hernias: a closer look at fascial architecture and aponeurotic passageways

From the clinical point of view, a proper diagnosis of spigelian, inguinal and femoral hernias may be relevant for orienting the patient's management, as these conditions carry a different risk of complications and require specific approaches and treatments. Imaging may play a significant role in the diagnostic work-up of patients with suspected abdominal hernias, as the identification and categorization of these conditions is often unfeasible on clinical ground. Ultrasound imaging is particularly suited for this purpose, owing to its dynamic capabilities, high accuracy, low cost and wide availability. The main limitation of this technique consists of its intrinsic operator dependency, which tends to be higher in difficult-to-scan areas such as the groin because of its intrinsic anatomic complexity. An in-depth knowledge of the anatomy of the lower abdominal wall is, therefore, an essential prerequisite to perform a targeted ultrasound examination and discriminate among different types of regional hernias. The aim of this review is to provide a detailed analysis of the fascial architecture and aponeurotic passageways of the abdominal wall through which spigelian, inguinal and femoral hernias extrude, by means of schematic drawings, ultrasound images and video clips. A reasoned landmark-based ultrasound scanning technique is described to allow a prompt and reliable identification of these pathologic conditions

High-resolution ultrasound-modulated optical tomography in biological tissues

We present a novel implementation of high-resolution ultrasound-modulated optical tomography that, based on optical contrast, can image several millimeters deep into soft biological tissues. A long-cavity confocal Fabry–Perot interferometer, which provides a large etendue and a short response time, was used to detect the ultrasound-modulated coherent light that traversed the scattering biological tissue. Using 15-MHz ultrasound, we imaged with high-contrast light-absorbing structures placed > 3 mm below the surface of chicken breast tissue. The resolution along the axial and the lateral directions with respect to the ultrasound propagation direction was better than 70 and 120 µm, respectively. The resolution can be scaled down further by use of higher ultrasound frequencies. This technology is complementary to other imaging technologies, such as confocal microscopy and optical-coherence tomography, and has the potential for broad biomedical applications

Very High-Resolution Ultrasound of the Distal Median Nerve

Objective: A very high-resolution (70 MHz) ultrasound device (VHRUS) has recently been approved for use in humans. The aim of this study was to use VHRUS to collect data on healthy subjects to propose some reference values for the digital branches of the median nerves of the hand. Methods: A VHRUS with 70 MHz linear array transducer was used to measure the cross sectional area of the median nerve at the wrist (CSAw) and digital branches (CSAf), largest and smallest fascicles, the fascicles number (Nfasc), the fascicle density (FD), the flattening ratio (FR) and CSAw/CSAf. Results: Data from 20 healthy subjects were obtained for both hands. The median nerve at the wrist and digital branches were properly identified without anatomical alterations. No differences were found between the right and the left hand. In the dominant hand, CSAw was 9.35 mm2 (4.57-12.35) and Nfasc was 24 (18-38). FD and FR were respectively 2.94 (2.47-4.91) and 2.74 (1.70-4.90). Conclusion: VHRUS technology can visualize the median nerves at the wrist, their internal structure and their small branches at the fingers, providing both a qualitative and quantitative assessment. Results from this study provide preliminary reference values in a young healthy sample. Significance: Most conventional ultrasound devices are not able to properly visualize the distal branches of the median nerve. In contrast, VHRUS allows to detect and measure smaller structures of the nerve, assisting in clinical practice

High-Resolution Ultrasound Imaging System for the Evaluation of the Vascular Response to Stent or Balloon Injuries in the Rabbit Iliac Arteries

For novel therapeutic approaches of cardiovascular diseases, the preclinical investigation is of paramount and required appropriate technologies. We investigated the use of high-resolution ultrasound imaging system to evaluate the progression of vascular lesions in a rabbit model. Animals underwent vascular injury using two standard procedures. A bare-metal stent was placed within the left iliac artery, and a balloon injury was induced in the contralateral artery. The animals were kept on a regular diet for 8 weeks. A Vevo3100© VisualSonic high-resolution ultrasound imaging system and the associated software VevoVasc were used for the longitudinal evaluation of the injured arteries and the distal abdominal aorta. The lumen size increased rapidly after the intervention in both iliac arteries. In the balloon-injured artery, the augmentation was transient and significantly reversed, inducing an alteration of the blow flow. In contrast, in the stented segment, the lumen size was maintained enlarged overtime. We demonstrated a significant correlation for the wall thickness and the lumen size between ultrasonic and histological quantification. High-resolution ultrasound imaging in rabbit iliac arteries and the distal abdominal aorta is feasible, reliable and of relevance to investigate novel strategies for the inhibition of hyperplasia induced with standard injury models

Skin Characterizations by Using Contact Capacitive Imaging and High-Resolution Ultrasound Imaging with Machine Learning Algorithms

We present our latest research on skin characterizations by using Contact Capacitive Imaging and High-Resolution Ultrasound Imaging with Machine Learning algorithms. Contact Capacitive Imaging is a novel imaging technology based on the dielectric constant measurement principle, with which we have studied the skin water content of different skin sites and performed image classification by using pre-trained Deep Learning Neural Networks through Transfer Learning. The results show lips and nose have the lowest water content, whilst cheek, eye corner and under-eye have the highest water content. The classification yields up to 83.8% accuracy. High-Resolution Ultrasound Imaging is a state-of-the-art ultrasound technology, and can produce high-resolution images of the skin and superficial soft tissue to a vertical resolution of about 40 microns, with which we have studied the thickness of different skin layers, such as stratum corneum, epidermis and dermis, around different locations on the face and around different body parts. The results show the chin has the highest stratum corneum thickness, and the arm has the lowest stratum corneum thickness. We have also developed two feature-based image classification methods which yield promising results. The outcomes of this study could provide valuable guidelines for cosmetic/medical research, and methods developed in this study can also be extended for studying damaged skin or skin diseases. The combination of Contact Capacitive Imaging and High-Resolution Ultrasound Imaging could be a powerful tool for skin studies