Limitations of intravenous digital subtraction angiography.

Eighteen digital subtraction angiography (DSA) examinations were retrospectively evaluated for factors that led to their erroneous interpretation. Overlapping vessels obscured pathologic conditions in five cases. In four cases the lesions were not adequately profiled by the DSA projections. Eight lesions were rendered inconspicuous by misregistration artifacts attributable to motion, either from swallowing or from pulsation of vessel walls. One diagnostic error was caused by poor opacification from a degraded contrast bolus secondary to low cardiac output.

Spectrum analysis in carotid sonography.

Numerous Doppler spectral parameters for measurement of carotid obstructive lesions have been developed in recent years. This proliferation of parameters has caused sonologists to wonder which are valid and should be used routinely. This review article surveys the most commonly used Doppler spectral parameters. The physiological basis for each parameter is considered along with clinical applications and limitations. The use of spectral parameters for measuring carotid stenoses is summarized by means of an algorithm.

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. This article discusses the methods for establishing Doppler velocity criteria for the identification of clinically significant carotid ICA stenosis, based on the new standard for arteriographic measurement.

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. Assessment of contained aortic rupture is best accomplished with CT, rather than ultrasound. Aortic dissection may be diagnosed with duplex sonography, but the extent of dissection and the circulatory ramifications are best evaluated arteriographically. This review article considers the pathology of aortic and iliac aneurysm, sonographic techniques for evaluating aneurysms, and manifestations of aneurysm complications. Sonographic assessment of aortic grafts also is considered.

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).

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.

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. This subject is complex, and an intimate command of abdominal vascular anatomy can only be achieved when detailed study is coupled with sonographic experience. It is hoped that the anatomic drawings and sonographic illustrations included in this work will assist the neophyte sonographer with the difficult task of mastering the anatomy and normal Doppler characteristics of abdominal vessels.

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. Although average sonologists may not be able to provide a precise diagnosis for a cardiac abnormality, they are able to recognize such abnormalities in a high percentage of cases by using these three views and by answering the following questions: (1) Is the heart in a normal position? (2) Is the heart size normal? (3) Are the ventricles equal in size? (4) Is there a septal defect? (5) Are the atrioventricular valves in a normal position? and (6) Is there any abnormality of the endocardium, myocardium, or pericardium? This article presents a practical approach to the detection of fetal cardiac anomalies using the four-chamber and outflow tract views. Examples of normal anatomy and cardiac pathology are provided as well as a listing of differential diagnoses that should be reviewed when certain abnormalities are visualized.

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. An unusually small thorax is usually obvious to the experienced sonographer, and thoracic masses are commonly observed on the routinely obtained four-chamber view of the heart. This article reviews the many causes of pulmonary hypoplasia with an emphasis placed on thoracic masses. Many examples of pathological fetal thoracic conditions are provided as well as a listing of differential considerations with regard to sonographic appearances of chest masses.

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. This report reviews the spectrum of findings encountered by sonographers while evaluating early pregnancy.

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 goal of this work is to present a practical approach to the abnormal fetal abdominal examination enabling the sonographer and sonologist to suggest precise differential diagnoses.