and was in complete remission state. US finding: A hyperechoic tumorwith rather broad marginal hypo-echoic zone was revealed in theanterior-superior segment of the right lobe of the liver. The shape of thetumor was cauliflower-like and it touched the middle hepatic vein.Metastatic carcinoma with central necrosis was suspected. Contrast-enhanced dynamic sonography using 2.5 mg of Levovist (300mg/ml)was performed, with pulse inversion harmonic imaging. Equipmentused was HDI-5000 (ATL) with a 5–2 MHz convex probe. In the earlyarterial phase, fine vessels appeared in the whole area of the tumor, andin the portal phase, the echo level of the tumor slightly increased. In theliver parenchymal image, the tumor was shown as a clear defect area.CT finding: A large heterogeneously high-density tumor with marginallow-density zone was observed in the plain CT. After contrast enhance-ment, the whole tumor was slightly enhanced also in the arterial toequivalent phase of dynamic CT. MRI finding: The tumor was visual-ized as a heterogeneously high-intensity area with a T1 weighted imageand a slightly high-intensity in the T2 weighted image. Hepatic arte-riography revealed a faint tumor stain of 5 cm in diameter, suppliedfrom the anterior-superior branch of the right hepatic artery and medialbranch of the left hepatic artery.Proof of diagnosis: Surgical resection of the tumor was performed.The pathological diagnosis was metastatic carcinoma from malignantmelanoma with severe deposit of melanin pigment. No necrotic areawas found in the tumor.Relevance: As for the cause of the hyper-echo-genecity of metastaticliver tumor, central necrosis due to ischemia is observed most often. Incases of hepatocellular carcinoma, fatty metamorphosis or sinusoidaldilatation are pointed out. However, in the present case, no such findingwas observed. As the cause of hyper echoic appearance in US and highdensity in plain CT, dence deposit of melanin pigment was possiblysuggested, in the present case.

32846

Is routine follow-up ultrasound to assess fetal growth warrantedwith the isolated finding of a single umbilical artery on initialcomprehensive fetal survey?Benoit R,* Copel J, Williams K, Ob-Gyn, Yale University School ofMedicine, New Haven, CT

Objective: The aim of this study was to describe the frequency ofdetecting intrauterine fetal growth restriction, SGA, or additional fetalanomaly with routine follow-up ultrasound recommended for isolatedsingle umbilical artery (SUA) on initial comprehensive fetal survey.Methods: We performed a retrospective review of 36,037 ultrasoundexaminations reported in our prenatal diagnosis center over a 5-yearperiod (1993–1998). We reviewed all reports containing two-vessel orsingle umbilical artery, between 15 and 42 weeks of gestation. A totalof 263 patients were identified. We excluded patients referred forsuspected two-vessel cord if these findings were not confirmed oncomprehensive examination.Results: A total of 207 pregnancies were identified with an antenataldiagnosis of two-vessel umbilical cord on comprehensive ultrasoundexamination. Concomitant fetal anomaly, abnormal karyotype, or an-euploidy marker was reported in 67/207 (32.3%). Isolated SUA wasreported in 140/207 (67.6%). We then excluded pregnancies withelevated hCG on maternal serum screen (n�1), multiple gestation(n�19), gestational diabetes, chronic hypertension, and any reportedmaternal complications (n�7). Among the group with isolated SUAdiagnosed on second-trimester fetal survey, a total of 48 returned to ourunit for at least one follow-up ultrasound with the reported indicationto assess fetal growth due to two-vessel cord, with no other reportedmaternal complication. In this group, none were noted to have an EFW�10th percentile at last ultrasound assessment, none were noted tohave an additional anomaly on subsequent scan, and 6/48 (12.5%) were

subsequently reported as three-vessel umbilical cord. Among all casesof isolated SUA scanned at least once after 30 weeks of gestation, 1/45(2%) had a reported estimated fetal weight (EFW) �10th percentile atlast scan.Conclusions: Routine follow-up ultrasound to assess fetal growth inthe singleton gestation with an isolated finding of single umbilicalartery on comprehensive anatomy survey is not recommended, giventhe low frequency of detecting additional anomalies and intrauterinegrowth restriction in our population.

32848

A new form of the Doppler string phantomReid J,* Beach K, Bioengineering, University of Washington, Seattle,WA

Objective: The aim of this study was to produce a test object that issuitable for testing the spatial and frequency response of Doppler flowmeasuring systems that do not have the disadvantages of current stringand flow phantoms. The new object should be suitable for routine usefor system characterization and quality control.Methods: A rotating disk was mounted in a water tank with the soundbeam perpendicular to the axis of rotation of the disk. The sound beamimpinged on the edge of the disk so that a Doppler signal resulted fromscattering by the radial roughness of the edge. A variable speed motorwas used to change the observed Doppler frequency over a range wideenough to allow the frequency response of the Doppler system to beplotted, even through the aliasing region.Results: The observed spectrum had the desired properties: a narrow-band spectrum that could be set to much higher frequencies than couldbe obtained from a flow object with an inner diameter of comparablesize. The thickness and roughness of the disk edge in the radialdirection were shown to set the strength of the backscatter. We are alsodeveloping other forms of this phantom, including one using the edgeof a moving band to produce a linear “flow” region.Conclusions: We have met the goal of making a single-frequency andhighly variable frequency test object for system response tests that isuseful for development or quality control. This new test object is farless difficult to construct and to use than are conventional stringphantoms. The use of a thick disk (with tapered edge to provide asmaller target area) as well as the damping of the water stops theundesired motion of the test object that plagues strings. The parts usereadily available and inexpensive materials.

32850

Ultrasonographic diagnosis of ureteral stones with acute renalcolic in 100 patientsHwang J,* Lee S, Radiology, Taichung Veterans General Hospital,Taichung, Taiwan

Objective: The aim of this study was to demonstrate the diagnosticefficacy of transabdominal ultrasonography (TAUS) in patients withureteral stones and acute renal colic.Methods: During a period of one and half year, 100 patients of ureteralstones with acute renal colic were performed with TAUS before intra-venous urography (IVU). There were 61 men and 39 women with anaverage of 56 Y/O. Diasonics SPA and GE Logic 700 scanner equippedwith dynamic foci of high-resolution transducer (4–7 MHz) were usedfor whole abdominal survey with emphasis on the kidneys, ureters, andurinary bladder.Results: TAUS can identify the echogenic stone(s) in the dilatedureteral lumen in 90 patients. The diagnostic accuracy was 95% (40/42)in U/3, 90% (18/20) in M/3, and 84% (32/38) in L/3 of ureteral stones,respectively. One patient with ectopic pelvic kidney and ureteral stoneand 2 pregnant patients with U-V junction stones were diagnosed

S216 Ultrasound in Medicine and Biology Volume 29, Number 5S, 2003