Characterization of Lens Based Photoacoustic Imaging System

Some of the challenges in translating photoacoustic (PA) imaging to clinical applications includes limited view of the target tissue, low signal to noise ratio and the high cost of developing real-time systems. Acoustic lens based PA imaging systems, also known as PA cameras are a potential alternative to conventional imaging systems in these scenarios. The 3D focusing action of lens enables real-time C-Scan imaging with a 2D transducer array. In this paper, we model the underlying physics in a PA camera in the mathematical framework of an imaging system and derive a closed form expression for the point spread function (PSF). Experimental verification follows including the details on how to design and fabricate the lens inexpensively. The system PSF is evaluated over a 3D volume that can be imaged by this PA camera. Its utility is demonstrated by imaging phantom and an ex vivo human prostate tissue sample

Color Flow Doppler Evaluation of Uterus and Ovaries and Its Optimization Techniques

Color flow Doppler (CFD) imaging provides valuable information about the vascularity of tissue, organs, or systems. CFD imaging is commonly used during the evaluation of uterus and ovaries in addition to gray-scale imaging and is a helpful imaging modality in the diagnosis of various pathologic conditions in gynecology and obstetrics. The main limitation of CFD imaging is its user dependency that may lead to misdiagnosis owing to the artifacts or pitfalls derived from improper technique, incorrect use of imaging parameters, and unawareness of physical properties of the modality by the user. This article summarizes the CFD imaging technique, the optimization of imaging parameters, and the useful findings in the evaluation of uterus and ovaries. © 2008 Elsevier Inc. All rights reserved

Endoanorectal Ultrasonography

Endoanorectal ultrasonography (EARUS) may be used for diagnosing various anorectal disorders. EARUS is easy to perform, has a short learning curve, and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized, and one can easily distinguish between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. The use of contrast agents can increase the accuracy of EARUS in the assessment of perianal fistulae. In addition, EARUS is an excellent alternative to expensive magnetic resonance imaging. Besides its use in incontinence and perianal sepsis, the presence of slight or massive submucosa] invasion in early rectal cancer may be imaged in greater detail. With 3-dimensional EARUS, it is possible to diagnose the anorectal diseases, in multiplane, with high spatial resolution, adding important information about the therapeutic decision. The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography with complementary techniques such as transvaginal and transperineal ultrasound are reviewed in this article