ISSN:0894-8771    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Microbubbles enhance ultrasonic signals, because they resonate in the ultrasound beam to boost the intensity by approximately 20 dB. This can be used to rescue failed B-mode and Doppler studies. However, it can also extend both methods into previously impossible applications, including evaluating the microvasculature of the myocardium and of tumors. Because the transit of an injected bolus can be tracked, transit time curves can be generated; these transit time curves may provide features that can discriminate between benign and malignant vasculature. New types of microbubble agents targeted to specific tissue types are under development; they may prove useful as therapeutic and diagnostic agents.

ISSN:0894-8771    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Liver transplantation is a widely accepted curative surgical procedure for certain diffuse and focal liver diseases. Patients who have undergone liver transplantation are at risk for a variety of complications, the most significant of which are rejection, vascular and biliary lesions, and malignant disease. Because sonography is the most frequently requested imaging procedure in such patients, familiarity with the spectrum of sonographic findings in liver transplant recipients is essential for the optimal performance and interpretation of sonography in this population. The author reviews current approaches to the sonographic evaluation of cadaveric whole-liver transplantations which should be of particular interest for radiologists and sonographers who may find themselves called on to image patients who have undergone liver transplantation.

ISSN:0894-8771    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The clinical utility of ultrasonography in the diagnosis of penile tumors and trauma has not yet been defined, and only a few cases have been reported worldwide. In benign cystic tumors, the sonographic features are those observed in other fluid cystic collections, whereas solid masses are characterized by an echotexture that can be hypoechoic or hyperechoic. Penile cancer, common in some geographical areas, appears as an inhomogeneous, ill-defined mass, usually limited to the glans penis or prepuce. Ultrasonography and magnetic resonance images arc particularly useful for staging the primary tumor, because they define the degree of involvement of the corpora cavernosa and determine the appropriate tumor-free level for amputation. Penile trauma commonly occurs during erection. The injury can occur anywhere along the shaft, but is more common at the base. It is associated with a tear of the tunica albuginea with extensive hematoma. On occasion, there may be rupture of the urethra and the corpus spongiosum. Blunt penile or perineal trauma can produce injury to the dorsal or cavemosal arteries with a cavemosal-sinusoidal space fistula leading to secondary high-flow priapism. These arteriovenous fistulas can be successfully treated with selective cmbolization. Dorsal penile vein thrombosis, and rupture of the dorsal vein, are the most frequent post-traumatic lesions observed in the venous system. Late complications of penile trauma include focal or diffuse fibrotic intracavemousal fibrosis. They can be easily identified with sonography as areas of hyperechogenicity that show reduced expansion during erection. They can cause impotence, especially in young, otherwise healthy men.

ISSN:0894-8771    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Transcranial Doppler ultrasound, a noninvasive tool for exploring the hemodynamics of intracranial vessels, has evolved significantly over the past decade. Blind vessel integration has been replaced by color Doppler sonography combined with B-mode ultrasound and pulse-wave Doppler. These modalities allow rapid, re-producible and accurate vessel identification, thus enhancing the detection and diagnosis of intracranial pathologies. Power Doppler is more sensitive than color Doppler in detecting tow-velocity flow and flow in small vessels, making it extremely useful for evaluating intracranial blood flow. Intravenous transpulmonary ultrasound contrast media increase the signal/noise ratio of blood flow and make vessels easier to identify. Power Doppler associated with ultrasound contrast improves the quality of transcranial Doppler imaging, allowing magnetic resonance angiography-quality images to be obtained at the patient's bedside. The techniques and clinical uses of transcranial Doppler are discussed, with emphasis on normal hemodynamic data values.

ISSN:0894-8771    

出版商:OVID    

年代:1998

数据来源: OVID