Carotid duplex sonography: a multicenter recommendation for standardized imaging and Doppler criteria.

A complex duplex carotid evaluation involves high resolution imaging and characterization of the carotid plaque as well as quantitative Doppler spectral analysis to determine the presence and degree of flow restriction. Each of the components of the examination is essential to evaluate the carotid arteries adequately for the presence of disease. Both of these components should be assimilated into a final report that can be used to determine who is at risk for embolic as well as flow restrictive disease. By carefully following the reporting system described in this paper, an accurate and reproducible means of evaluating the carotid arteries can be achieved that permits comparison of studies. In addition, this will allow accurate communications among institutions and help to insure a better understanding of the etiology and pathogenesis of atherosclerotic carotid artery disease.

Assessment of cardiac size on portable chest films.

Using both anthropomorphic phantoms and human patients, the authors have shown that the effects on cardiothoracic (CT) ratio of changing from the posteroanterior (PA) to the anteroposterior (AP) projection are much greater than the effect of reducing the anode-to-film distance (AFD). This is because, in the AP projection, not only is the transverse diameter (TD) of the heart much farther from the film (and its image is therefore enlarged), but the TD of the chest is usually closer to the film and its image is reduced in size. These factors, operating in different directions, cause a major change in the CT ratio. The authors have shown that small hearts are magnified more than large hearts by changing from PA to AP, and that the position of the TD of the thorax (whether it is farther anterior or farther posterior) markedly affects what happens to the CT ratio when the AFD is changed. Because of this, it is impossible to predict accurately what effects a given AFD and projection will have on the CT ratio. However, using approximate correction factors (-12.5% of CT ratio for a 40 in AFD, AP film and -10% of CT ratio for a 72 in AFD, AP film) a clinically useful determination can be rapidly made as to whether the heart is enlarged or not.

In vivo acoustic attenuation in liver: correlations with blood tests and histology.

Results of in vivo attenuation measurements in the liver have been obtained in 26 normal controls and in 51 patients with chronic diffuse liver disease. A modified real-time sector scanner was used for narrow-band amplitude attenuation examination. In the control group (people without apparent liver disease), a statistically significant correlation was found between acoustic attenuation in liver and two blood tests reflecting liver function: serum albumin (n = 24, r = 0.67, p = 0.002) and prothrombin time (n = 23, r = 0.63, p = 0.019). There was a statistically significant positive correlation between attenuation and fat for all biopsied patients (n = 51, r = 0.32, p = 0.023) and for patients with minimal fibrosis (n = 25, r = 0.45, p = 0.027). Although no correlation with fibrosis was found for all patients, in the group of patients with minimal fat there was a correlation with portal fibrosis (n = 33, r = 0.37, p = 0.035). This double blind prospective study shows that in the liver: (1) attenuation estimates appear correlated with clinical parameters (blood tests) in normal volunteers, and (2) large changes in fat affect narrow-band acoustic attenuation estimates to a greater degree than severe portal fibrosis in patients with chronic diffuse liver disease. Further research is needed before these estimates can become a clinical tool.

Noninvasive evaluation of hepatic fibrosis using frequency demodulation of ultrasound signals.

A new ultrasound image can be produced by frequency demodulation (FM) of the conventional ultrasound signal. This new FM image appeared to produce a more accurate representation of the fine structure of the liver. The individual features of the FM image were correlated with hepatic portal fibrosis and cirrhosis on liver biopsy in 34 patients with minimal hepatic fat and sinusoidal collagen. An overall ultrasound score correlated with portal fibrosis (r = 0.788; P less than 0.001). We conclude that the FM image may be helpful in measuring and following the progression of hepatic fibrosis in patients with chronic liver disease.

Frequency-demodulated US: evaluation in the liver. Work in progress.

Frequency modulated (FM) imaging is a new ultrasound (US) modality that uses pulse-echo signal instantaneous frequency in addition to the conventional envelope information. Eight features of the FM image in nondiseased livers are described. The technique is evaluated in a study of 34 patients with biopsy-proved diffuse liver disease. Visual grading of FM US image features shows good correlation with levels of biopsy-graded hepatic fibrosis. Patients with diffuse parenchymal liver disease often exhibit evidence of the abnormality when FM liver imaging is used, while such evidence is not as well demonstrated with conventional envelope (AM) imaging.

Hepatic artery-biliary fistula. An unusual complication of infusion therapy.

This report describes a patient with carcinoid metastatic to the liver in whom a hepatic artery catheter was placed for infusion therapy. This resulted in a previously unreported complication of a hepatic artery-biliary fistula. The clinical presentation of this complication and mode of management are described. The etiologic factors responsible for this complication are discussed. It is speculated that as more aggressive therapy for hepatic metastases is undertaken, this potential complication will be seen more frequently.