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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.

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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.

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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.

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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.

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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.

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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. This figure represents only one segment of USA health care costs and, if all segments were considered, the 1992 total for vascular laboratory services would probably approach one billion USA dollars. The expansion of vascular laboratory utilization is attributed to a number of factors: (i) increased recognition of the clinical value of non-invasive vascular studies; (ii) replacement of invasive (angiographic) procedures; (iii) expanded surveillance application; (iv) the verification of carotid endarterectomy for treatment of carotid stenosis; (v) widespread, unlimited access; (vi) over-utilization; (vii) greed. Widespread awareness of the crisis in USA health care funding has imposed cost-containment pressure where virtually none existed previously. The vascular laboratory is no exception to this trend, and the following measures have been suggested for controlling vascular laboratory costs: (i) demonstration of the clinical and cost effectiveness of non-invasive vascular studies; (ii) utilization review; (iii) pre-approval of requests for vascular studies; (iv) linkage of vascular study reimbursement with clinical diagnosis; (v) limitations on self-referral; (vi) reduced reimbursement; (vii) capitation; (viii) diagnosis-related reimbursement; (ix) accreditation. This article summarizes the factors that have led to increased utilization of vascular laboratory services, and discusses methods proposed for containing vascular laboratory expenditure.

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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. Neither SMA nor splenic artery blood flow was increased in patients with normal-sized spleens; however, blood flow was significantly elevated in patients with splenomegaly. Total splanchnic blood flow in patients was also significantly elevated compared with healthy subjects. Total splanchnic blood flow in patients with normal-sized spleens was not significantly elevated compared with healthy subjects, but splanchnic flow was significantly increased in patients with splenomegaly. CONCLUSION: Blood flow is increased in the SMAs and splenic arteries of patients with cirrhosis and portal hypertension. Increased splanchnic blood flow associated with cirrhosis may occur exclusively in patients with splenomegaly.

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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).

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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.

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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). Among symptomatic patients with acute DVT, 26 of 34 (76%) patients had an above-knee thrombus and only eight of 34 (24%) patients had a thrombus isolated to the calf. In comparison, only three of 25 (12%) asymptomatic patients with DVT had an above-knee thrombus and 22 of 25 (88%) patients had a thrombus isolated to the calf veins (most involving only one venous segment). Failure to examine the calf veins, particularly in asymptomatic patients, would result in missing at least half of patients with DVT. Alternatively, since all cases of iliac vein DVT extended into the femoropopliteal segment, failure to visualize the iliac veins is unlikely to miss patients with DVT. Our results suggest merit to routine examination of the deep femoral, anterior tibial, and particularly the soleal (but not the gastrocnemius) veins and also to use of an imaging technique to detect congenital duplications of the superficial femoral and popliteal veins.

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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. Venography was the standard for comparison of results. RESULTS: Fifty-six percent of CDFI examinations of the calf vein were technically adequate. The remaining studies were compromised technically by limb swelling and/or obesity. For the technically adequate CDFI studies, calf vein thrombosis was detected in eight of 10 patients. Calculated sensitivity in this cohort was 80%, and specificity was 97%. The sensitivity of CDFI for acute calf DVT in all patients, regardless of image quality, was 42%. CONCLUSION: These observations suggest that state-of-the-art CDFI is not an accurate examination for acute calf vein DVT in asymptomatic postoperative patients. CDFI is associated with a high rate of technically compromised studies and relatively low sensitivity in studies that are deemed technically satisfactory. These observations do not preclude the use of CDFI in postoperative patients for detection of thrombus extension into the popliteal vein or for detecting thrombosis of more proximal lower extremity veins.

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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.

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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.

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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. Duplex sonography is not very effective in providing a "global" perspective of the cerebral vasculature, because only the cervical portion of the carotid arteries can be examined in detail. The best documented and most clearly effective use of duplex sonography is for detecting severe obstructive lesions in the carotid artery that might warrant endarterectomy in patients with cerebral hemispheric symptoms. The role of duplex sonography in the choice between medical and surgical therapy in asymptomatic patients with carotid artery stenosis is controversial, because the indications for endarterectomy are unclear in these patients. The capacity of duplex sonography to assess plaque composition may ultimately prove to be quite valuable for selecting therapeutic options and for evaluating the effectiveness of medical therapy. Meanwhile, information concerning the clinical value of this use of duplex sonography remains limited.

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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. For the inexperienced sonographer, we describe our current technique, which is easy, quick, accurate, and well tolerated by patients.

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