Duplex sonography of the portal venous system: pitfalls and limitations.

Duplex pulsed-Doppler sonographic examinations of the portal venous systems of 14 patients were reviewed, and the results were compared with the findings of other examinations including endoscopy and angiography. The sonograms of virtually every patient in the sample showed at least one of four pitfalls. The "mirror-image" artifact, in which the Doppler signal contained simultaneous and symmetric elements on both sides of the zero baseline, was identified in 11 patients (79%). The "flip" artifact, in which the Doppler signal would either flip from one side of the zero baseline to the other or would indicate a direction of blood flow opposite to that normally expected, was seen in six patients (43%). In four patients (29%), a Doppler flow signal could not be obtained from small vessels that were identified on standard real-time images. In 10 patients (71%), important vascular channels including bleeding gastroesophageal varices were obscured by bowel gas, ascites, or the patient's body habitus. Duplex sonography may still provide useful information about portal venous hemodynamics. However, it remains a prodigious technical undertaking whose accuracy can be severely hampered by artifacts and inherent technical difficulties.

Cava-suprarenal line: new position for sonographic imaging of left adrenal gland.

Because of overlying attenuating structures, sonographic imaging of the left adrenal gland is often difficult, especially in obese or pediatric patients. In a series of 50 consecutive patients, the left adrenal glands were examined in both the conventional right posterior oblique (RPO) position and using the new cava-suprarenal line (CSL) position. The CSL position permitted identification of the left adrenal gland in 90% of the patients; in contrast, the gland could be demonstrated in only 60% of the patients using the conventional RPO position. With the CSL position, the left adrenal gland could be imaged in half the time required with the conventional RPO position. The improved ability to demonstrate the left adrenal gland as well as the reduction in the required scanning time was particularly marked in obese and pediatric patients.

Gallbladder examinations: a comparison between sonography and radiography.

For the past 50 years, oral cholecystography has been the standard study of radiographic evaluation of the gallbladder with a 98% accuracy level. In the last few years, ultrasound has achieved a similar degree of accuracy; this newer imaging modality has been predicted by some experts to soon become the initial procedure for gallbladder evaluation. It is essential to become aware of the advantages and disadvantages of both oral cholecystography and abdominal ultrasound to be able to use both of them to the best diagnostic advantage.