Tricky and interesting carotid cases.

In many instances, ultrasound examination of the carotid arteries is a straightforward matter, with easily recognized atherosclerotic disease and well-defined parameters for assessment of carotid obstruction. In some circumstances, however, hemodynamic conditions may skew the Doppler velocity and waveform findings in potentially confusing ways, possibly cause misdiagnosis. This is the "tricky" aspect of carotid sonography of which all vascular ultrasound practitioners must be wary.

New Doppler parameters for carotid stenosis.

The recently published clinical trials of carotid endarterectomy marked a turning point in carotid sonography, because they provided justification for seeking carotid stenosis with ultrasound in both symptomatic and asymptomatic patients. These trials also were a turning point because they set a new standard for measuring carotid stenosis from arteriograms, based on the comparison of the least diameter of the residual internal carotid artery (ICA) lumen and the diameter of the normal, distal ICA. The adoption of this new standard for arteriographic measurement has necessitated the redefinition of velocity criteria for duplex Doppler diagnosis of ICA stenosis.

Fetal gastrointestinal anomalies.

A review of fetal gastrointestinal anomalies is presented. Normal abdominal development and anatomy, including basic embryology and recommended ultrasound techniques, are first outlined. Next is a more detailed discussion of the abnormal examination, including abdominal wall defects and intra-abdominal abnormalities.

The fetal thorax: noncardiac chest anomalies.

Fetal thoracic anomalies often lead to pulmonary hypoplasia with subsequent fetal or neonatal demise. Therefore, in utero sonographic identification of these anomalies is important. Unlike cardiac anomalies, most noncardiac thoracic abnormalities are easily detected with ultrasound.

First-trimester ultrasound: the essentials.

A review of first-trimester ultrasound findings is presented. The normal first trimester, including practical embryology and pregnancy dating, is first discussed. Abnormal first-trimester findings, including sonographic evaluation of the failing pregnancy, ectopic pregnancy, gestational trophoblastic disease, and first-trimester cystic hygroma, are then stressed.

The fetal heart: a practical sonographic approach.

Structural abnormalities of the heart are a fairly common problem, affecting more than 8 of 1,000 newborns annually in the United States. Therefore, sonographic detection of these anomalies in utero is important. It is possible to detect a high percentage of fetal cardiac anomalies through proper sonographic examination using three central views of the heart: (1) the four-chamber view; (2) the aortic outflow tract view; and (3) the pulmonary output tract view.

The clinical and financial impact of non-invasive vascular testing in the USA.

Health care costs in the USA have increased dramatically during the past 10 years, and it is widely believed that they have reached crisis dimensions. Vascular laboratories are a segment of the USA health care industry that has experienced particularly rapid growth in the last decade. In 1992, USA Medicare payments (for patients > or = 65 years) totalled US$304,492,588 for 3,673,695 non-invasive vascular studies.

Splanchnic blood flow in patients with cirrhosis and portal hypertension: investigation with duplex Doppler US.

Purpose: To investigate splanchnic blood flow changes in patients with hepatic cirrhosis and portal hypertension.

Materials And Methods: Duplex Doppler ultrasound (US) was used to measure blood flow in the superior mesenteric artery (SMA) and splenic artery in 20 patients with biopsy-proved cirrhosis and clinical evidence of portal hypertension, and in 20 healthy volunteers who were matched for age and sex.

Results: Mean SMA and splenic artery blood flow was significantly greater in the patients than in healthy subjects.

Sonographic diagnosis of diffuse liver disease.

Sonography provides valuable information about diffuse liver disease. This article reviews the normal features of hepatic parenchyma as well as the sonographic findings that characterize important pathological conditions. Included are hepatitis, opportunistic infection, diffuse metastasis, fatty liver, hepatic fibrosis, and cirrhosis.

Sonographic diagnosis of hepatic vascular disorders.

Perhaps the most valuable application of duplex sonography in the abdomen is in the diagnosis of vascular disorders of the liver. Duplex sonography provides an accurate assessment of the portal and hepatic venous systems that is both noninvasive and convenient, because the examination can be conducted at the bedside. In this article, the normal features of portal and hepatic venous flow are considered as well as the sonographic manifestations of pathological conditions, including: (1) portal hypertension; (2) portosystemic collaterals; (3) portal vein thrombosis; and (4) hepatic vein thrombosis (Budd-Chiari syndrome).

Distribution of acute lower extremity deep venous thrombosis in symptomatic and asymptomatic patients: imaging implications.

The ability of noninvasive imaging modalities to diagnose lower extremity DVT depends, in part, on the anatomic location of the thrombus. To define the pattern of thrombus formation in symptomatic and asymptomatic high-risk patient populations, 172 consecutive lower extremity venograms were submitted to blinded, retrospective interpretation. Acute DVT was present in 59 venograms (34 symptomatic and 25 asymptomatic patients).

Insensitivity of color Doppler flow imaging for detection of acute calf deep venous thrombosis in asymptomatic postoperative patients.

Purpose: Although color Doppler flow imaging (CDFI) has been shown to accurately depict calf vein thrombosis in symptomatic patients, this technique has not been proved accurate for detection of calf vein thrombosis in a population restricted to asymptomatic postoperative patients.

Patients And Methods: To evaluate the accuracy of CDFI in asymptomatic postoperative patients, both CDFI and contrast venography were performed on 78 limbs of 76 patients without symptoms of deep venous thrombosis (DVT) who had undergone either hip or knee replacement. CDFI and venographic examination were interpreted blindly with respect to the results of the other modality or clinical findings.

Aortic and iliac aneurysm.

Sonography is a highly accurate method for assessing the abdominal aorta and the iliac arteries for aneurysms and their complications. Proper technique is required, however, to ensure diagnostic accuracy. With respect to abdominal aneurysms, the principal duplex applications are diagnosis, measurement, and follow-up after surgery.

Basics of abdominal and pelvic duplex: instrumentation, anatomy, and vascular Doppler signatures.

The capabilities and limitations of color duplex sonography are briefly discussed in this article. Following this, basic Doppler and hemodynamic principles are reviewed, with emphasis on the concept of arterial pulsatility, as reflected in Doppler velocity waveforms. The bulk of the article is devoted to abdominal vascular anatomy and a review of the Doppler signatures that facilitate identification to abdominal vessels.

Duplex sonography of the cerebral arteries: efficacy, limitations, and indications.

This review considers the capabilities and limitations of duplex sonography in the diagnosis of abnormalities of the cerebral vasculature. Duplex sonography is an elegant union of B-mode and Doppler sonography that provides valuable information about atherosclerotic obstruction of the carotid arteries. Duplex sonography also can be used to evaluate, in a general way, the composition of carotid atherosclerotic plaque, and in this respect, it is unique among imaging procedures.

Techniques for color flow sonography of the lower extremity.

Color flow sonography permits noninvasive examination of the deep venous system in the lower extremity. In many patients, the modality is sufficiently accurate to serve as the sole diagnostic procedure for suspected deep venous thrombosis. Over 1,500 color flow sonographic examinations of the lower extremity have been performed at our institutions with various scanning techniques.