Abnormal Doppler ultrasound signals were detected in 44 of 47 patients with primary malignant tumors of the liver, kidney, adrenal gland, or pancreas (94%). Two different signal types were noted: a high-velocity signal (n = 38) with Doppler shifts exceeding 3 kHz (at an insonating frequency of 3 MHz) and a very low-impedance signal (n = 9) demonstrating little systolic-diastolic variation. In three patients, both types were present. In 19 patients, histologic (n = 12) and/or angiographic (n = 16) correlation was available. Among 13 patients with angiographic studies and signals over 3 kHz, arteriovenous shunting was demonstrated in six. The ratio of the systolic to diastolic Doppler shift is a function of vascular impedance. This systolic/diastolic index was less than 3 in eight patients with histologic correlation. All eight had prominent vascular spaces, and the flow in such thin-walled, endothelium-lined spaces would account for the low-impedance signals. Of nine patients with systolic/diastolic indexes of 3 or less and angiographic correlation, three had marked and four had moderate tumor staining.

Ultrasound imaging artifacts of acoustic origin relating to resolution, propagation path, and attenuation are reviewed. Lateral and axial resolution limitations are artifactual in nature since a failure to resolve means a loss of detail and two adjacent structures may be visualized as one. Apparent resolution close to the transducer (speckle) is not directly related to tissue texture but is a result of interference effects from the distribution of scatterers in the tissue. Reverberation produces a set of equally spaced artifactual echoes distal to the real reflectors. The mirror image artifact is the presentation of objects that are present on one side of a strong reflector, appearing on the other side as well. Shadowing and enhancement are useful artifacts for determining the nature of masses. Enhancement results from low attenuation objects in the sound path while shadowing results from strongly reflecting or strongly attenuating objects. Additional artifacts include section thickness, refraction, multipath, side lobe, grating lobe, focal enhancement, comet tail, ring down, speed error, and range ambiguity.

Two methods are used to estimate ultrasound attenuation in liver. These were based on amplitude change and frequency change as a result of depth dependent attenuation. Evaluation of the two methods against a family of calibrated phantoms yielded correlation coefficients of 0.98 and 0.99, respectively. Liver attenuation in 26 control subjects was 0.50 and 0.52 dB/MHz/cm, respectively. Liver attenuation was estimated in 50 patients who later underwent liver biopsy. Comparison with quantitative histologic results showed that the presence of fat alone accounted for the increased attenuation associated with cirrhosis. Similar high attenuation values were found in patients with fatty infiltration. Fibrosis alone did not result in elevated liver attenuation. Cirrhotics without fatty infiltration had attenuation similar to that of the controls. Mechanisms of action are discussed.

Absence of the portal vein with systemic visceral venous return was demonstrated in an 8-year old girl with oculoauriculovertebral dysplasia (Goldenhar syndrome) during preoperative evaluation of a liver mass. Congenital absence of the portal vein is a rare malformation of potential clinical significance.

MRU is a valuable and well tolerated investigation for evaluating painful hydronephrosis in pregnancy. There are characteristic and differing urographic appearances in physiological and calculous obstruction.