Doppler ultrasonography (US) is usually the first-line modality for evaluating flow in native liver vessels and transjugular intrahepatic portosystemic shunts (TIPS). Waveforms, which represent flow in each of the major vessels and in TIPS, have been well described. The appearance of these waveforms should be recognized, and the mechanisms behind their generation should be understood by those interpreting these examinations. Understanding how waveforms are formed--that is, their mechanisms for generation--is predicated on knowing basic vascular Doppler concepts and established nomenclature. This article is a review of these basic concepts and nomenclature as applied to the interpretation of liver Doppler US waveforms.

The authors review and classify errors in 182 cases that were presented at problem case conferences between August 1986 and October 1990. Errors were classified by means of a system developed 20 years ago and by means of a system developed within the past several years. The authors found that sources of error have changed very little. Errors usually involved failure to consult old radiologic studies or reports, limitations in imaging technique, acquisition of inaccurate or incomplete clinical history, location of a lesion outside the area of interest on an image, lack of knowledge, failure to continue to search for abnormalities after the first abnormality was found, and failure to recognize a normal biologic variant. Errors included 126 perceptual errors (64 false-negative, 15 false-positive, and 47 misclassification errors) and 56 mishaps, including 38 complications and 18 communication errors. In seven cases nonperception errors occurred because established departmental routines were not followed, and in nine cases a new departmental routine was established after a complication occurred. Departmental policy exerts less effect on perception and interpretation errors.

No abstract

To understand hepatic vein (HV) and portal vein (PV) duplex waveforms and their normal and respiratory variations, HV and PV duplex sonography with simultaneous electrocardiograpy was performed on 11 volunteers. Absolute velocities of the waveforms' components and their ratios were determined at mid· in· spiration, full inspiration, full expiration, and Valsalva maneuver. The normal HV waveform was variable in shape and component velocities and ratios but essentially consisted sequentially of (1) an antegrade systolic wave resulting from movement of the tricuspid annu• lus toward the cardiac apex and occurring shortly after QRS; (2) a retrograde v-wave resulting from atrial overfilling and occurring immediately after the T · wave; (3) an antegrade diastolic wave resulting from opening of the tricuspid valve and occurring shortly after the T-wave; and (4) a retrograde a· wave resulting from N ormal hepatic vein (HV) and portal vein (PV) duplex Doppler waveforms show cyclic phasicity that is more prominent in the HV. The nature of these waveforms is not well understood by most radiologists, and it is unclear even in the sono~ graphic literature whether this phasicity is cardiac or respiratory in origin.,_, It also has been shown that tricuspid regurgitation and diffuse hepatocellular disease can affect the shape of these duplex Doppler atrial contraction and occurring immediately after the P-wave. The ratio of the maximum systolic velocity to maximum diastolic velocity varied from 1.0 to 2.8 (mean 1.4). Systolic-to-diastolic ratio decreased during inspiration but was always greater than 0.6 and increased during expiration. The Valsalva maneuver di~ minished waveform pulsatility. PV waveforms were more triphasic than biphasic but less pulsatile, flow was totally antegrade, and respiratory changes were less remarkable than HV waveforms. All normal HV and most normal PV waveforms showed multiphasic· ity that corresponded to cyclic cardiac changes. The shapes of these waveforms were variable and were modified by respiratory movements. KEY WORDS: Liver, duplex; Hepatic and portal veins, Doppler flow varia· tions.waveforms by changing the velocities of their various components and their velocity ratios.M Because liver dysfunction can be the initial manifestation of some of these diseases, radiologists are in a position to make a specific diagnosis from the changes that occur in the shape and velocity ratios of these waveforms. However, they must first be familiar with the various components of the normal waveforms, their ratios, and their normal and respiratory variations.The purposes of this study were (1) to illustrate the Received October 2 .• 1991; from the Department of Radiology, nature of the various components of the normal HV

Transsphenoidal encephaloceles are rare congenital anomalies that may be immediately apparent in infants that present with multiple cranial midline defects. They should also be suspected in patients presenting with cerebrospinal fluid rhinorrhea, an epipharyngeal soft tissue mass, a visual defect, or an endocrinologic disturbance, especially when associated with midfacial and optic nerve anomalies. Plain x-ray films of the skull may show absence of the sellar floor and a soft tissue mass; the diagnosis is confirmed by computed tomography scanning. Surgical therapy may be indicated for persistent cerebrospinal fluid rhinorrhea, symptomatic epipharyngeal respiratory distress, or progression of neurological deficits. Two cases of transsphenoidal encephalocele are reported.