Prenatal evaluation of mesenchymal hamartoma of the liver: gray scale and power Doppler sonographic imaging.
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Adult↗
Biomedical subjects
T C Winter
Publications and source records attributed to T C Winter.
CT angiography of the visceral vessels.
CT angiography (CTA) is a promising new technique for vascular imaging. This review focuses first on the technique necessary for successful scanning of the visceral vessels. As in many new modalities, there are different protocols for scanning and rendering of images. The relative strengths and weaknesses of these different approaches are discussed. A discussion of the applications of CTA to depict normal and abnormal anatomy of the visceral vessels follows. These applications include celiac stenosis, splenic artery aneurysms, evaluation for hepatic arterial anatomy before liver transplantation, visceral arterial anatomy in pancreaticoduodenal surgery, the superior mesenteric artery in intestinal ischemia, vascular encasement in patients with pancreatic neoplasms, and, finally, the hepatic vessels before hepatic tumor resection.
Angiography↗
MR angiography of the portal venous system.
MR angiography (MRA) has become an increasingly important and practical clinical tool for the noninvasive assessment of abdominal vessels. Both two-dimensional time-of-flight and phase contrast techniques allow accurate evaluation of the portal venous system. This article reviews these two MRA techniques and discusses their impact on the diagnosis of vascular abnormalities of the portal venous system.
Humans↗
MR angiography of the peripheral vasculature.
MR angiography (MRA) for the evaluation of peripheral arterial occlusive disease is a rapidly evolving technique. Recent prospective clinical trials have indicated that MRA may play an important role in the evaluation of patients with peripheral arterial disease. This article discusses the pertinent technical aspects and limitations of peripheral MRA as well as some of the clinical data available.
Angiography↗
Automatic fetal head measurements from sonographic images.
RATIONALE AND OBJECTIVES: We designed an image processing technique to automatically measure the biparietal diameter (BPD) and head circumference (HC) from prenatal sonograms. We evaluated the performance of the algorithm by comparing the resulting measurements with those made by experienced sonographers. METHODS: Thirty-five digitized sonograms of the fetal head were obtained during routine imaging. The BPD and HC were automatically computed by detecting the inner and outer boundaries of the fetal skull using the computer vision technique known as the "active contour model." Six experienced sonographers also measured the BPD and HC on these images. RESULTS: The algorithm failed to locate the boundaries in two of the 35 cases. For the remaining cases, the mean absolute difference between the automated measurements and the average of the six observers was 1.4% for BPD and 2.9% for HC. The correlations were .999 for the BPD and .994 for the HC. The computer's measurements were no different from the six observers' measurements than the observers' measurements were from one another. CONCLUSION: The tested algorithm effectively and accurately measures BPD and HC automatically. We are currently in the process of integrating this algorithm into an ultrasound machine.
Algorithms↗
Imaging of complications in liver transplantation.
Hepatic transplantations are being performed with increasing frequency, leading to greater demand for accurate evaluation of related complications. Ultrasonography (US) is the primary screening technique for detection of vascular complications of hepatic transplantation: angiography is used to confirm the US findings or when the US study is suboptimal. Hepatic artery thrombosis, the most common (as high as 42% of pediatric cases; 4%-12% of adult cases) and important vascular complication, may be associated with bilomas, infarcts, or abscesses at gray-scale US and absence of proper hepatic and intrahepatic arterial flow at Doppler analysis. Hepatic artery stenosis (seen in 11% of cases) is suspected if a focal accelerated velocity of greater than 2-3 m/sec with turbulence is seen at or distal to the stenosis or if a tardus parvus pattern of intrahepatic arterial flow is seen. In cases of inferior vena cava thrombosis and stenosis, US may show echogenic thrombus or obvious narrowing, with a substantially increased flow velocity through the stenosis or reversal of flow in the hepatic veins. Biliary complications occur relatively often (13%-25% of cases) after liver transplantation; bile leakage and biliary stricture, the most common biliary complications, are seen as a fluid collection and a stricture, respectively. Although acute rejection is one of the most serious complications affecting graft survival, it cannot be reliably detected with available diagnostic tests or radiologic methods.
Anastomosis, Surgical↗
Upper gastrointestinal tract and abdomen: water as an orally administered contrast agent for helical CT.
PURPOSE: To evaluate the use of orally administered water as a negative contrast agent and intravenously administered glucagon in helical computed tomography (CT) of the upper abdomen. MATERIALS AND METHODS: Ninety-eight adult patients underwent 102 helical CT examinations. Patients received 700 mL of water orally 30 minutes before and another 350 mL of water orally with 1 mg of glucagon intravenously just before CT. The amount of water actually ingested was recorded. Luminal distention at five sites was graded on a three-point scale; depiction of six normal anatomic structures was evaluated. RESULTS: Luminal distention improved with the amount of water ingested in four of the five sites (P < .03 in three sites). Depiction of all six normal anatomic structures improved with increasing luminal distention (P < .001). The normal duodenal papilla was seen in 42% (83 of 198) of the examinations. Of 87 patients who had previously undergone CT with positive oral contrast agents, 89% (n = 77) preferred the water, 11% (n = 10) had no preference, and none preferred the positive agent (P < .001). Upper gastrointestinal tract abnormalities were easily recognized and depicted. CONCLUSION: Water is an efficacious negative contrast agent for evaluation of the upper gastrointestinal tract during helical CT.
Administration, Oral↗
Extrapancreatic gastrinoma localization: value of arterial-phase helical CT with water as an oral contrast agent.
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Administration, Oral↗
Amniotic fluid alpha-fetoprotein determination at the time of genetic amniocentesis: has it outlived its usefulness?
The purpose of this retrospective study was to evaluate the utility of routine measurement of amniotic fluid alpha-fetoprotein levels at the time of second trimester genetic amniocentesis (mean gestational age, 17.3 weeks +/- 2.5 weeks standard deviation; median, 16.8 weeks; range, 15 to 22 weeks). During the study period 7174 patients underwent second trimester genetic amniocentesis. Outcome data were available in all cases. In 79 (1.1%) cases the amniotic fluid alpha-fetoprotein level was > or = 2.0 multiples of the median. Thirty-three of the 79 (42%) patients had normal ultrasonograms, and in 31 of 33 (94%) the amniotic fluid alpha-fetoprotein level was between 2.0 and 3.0 multiples of the median. Forty-six of the 79 (58%) patients had abnormal ultrasonographic findings, and of these, 82% were neural tube defects, abdominal wall defects, or cystic hygromas. Acetylcholinesterase was positive in 37 cases, all of which had abnormal ultrasonographic findings. None of the fetuses with negative findings on sonographic screening had detectable abnormalities at birth. In this study, with over 7000 patients, amniotic fluid alpha-fetoprotein and acetylcholinesterase levels did not increase the detection of fetal abnormalities. On the basis of these results, routine measurement of amniotic fluid alpha-fetoprotein level at the time of routine genetic amniocentesis (15 to 22 weeks) does not appear justified.
Abdominal Muscles↗
Testicular carcinoma in a patient with previously demonstrated testicular microlithiasis.
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Adult↗
Hepatic arterial anatomy: demonstration of normal supply and vascular variants with three-dimensional CT angiography.
Three-dimensional (3D) helical computed tomographic (CT) angiography is a promising method of determining vascular anatomy. This technique is useful in delineating the arterial anatomy of the liver, demonstrating the normal anatomy and vascular variants in a highly visual fashion. The "typical" hepatic arterial anatomy occurs in only 55% of the population, and numerous variants exist; the standard classification system for hepatic arterial anatomy includes 10 variations. After helical scanning, postprocessing with reconstruction algorithms such as shaded surface display and maximum-intensity projection provides highly graphic, easily understandable views of vascular anatomy. The 3D CT angiograms, with their global view of the anatomy and inherent advantage of volumetric rotation of the vascular system, are useful to surgeons and others with limited experience in interpreting axial anatomy. Determination of hepatic arterial anatomy with 3D CT angiography has already been shown to be clinically useful in patients being evaluated for liver transplantation.
Adult↗
Trisomy 13 syndrome: prenatal US findings in a review of 33 cases.
PURPOSE: To determine the type and prevalence of prenatal ultrasound (US) findings in fetuses with trisomy 13. MATERIALS AND METHODS: Prenatal US findings in 33 consecutive fetuses with trisomy 13 and in 200 karyotypically normal fetuses were reviewed and compared. RESULTS: One or more abnormalities were found in 30 fetuses (91%). Major anomalies detected by means of US included holoprosencephaly (13 [39%]) or other central nervous system anomalies (19 [58%]), facial anomalies (15 [48%]), and renal (11 [33%]) and cardiac (16 [48%]) defects. Growth retardation was also present in 16 (48%). Echogenic chordae tendineae were seen in 10 (30%), which includes seven (39%) of 18 fetuses examined before 20 menstrual weeks (compared with four [2%] of 200 fetuses in the reference group [P < .001]). Other findings not generally associated with trisomy 13 but present in this series included a large cisterna magna (six [18%]), mild cerebral ventricular dilatation (three [9%]), nuchal thickening or cystic hygroma (seven [21%]), and a hypoplastic left side of the heart (seven [21%]). CONCLUSION: Prenatal US can help detect one or more anomalies in most fetuses with trisomy 13; thus, US finding can indicate whether karyotype should be tested.
Adolescent↗
Helical CT during arterial portography: optimization of contrast enhancement and scanning parameters.
PURPOSE: To determine the optimal scanning parameters for helical computed tomography during arterial portography (CTAP) of the liver. MATERIALS AND METHODS: Single- and double-helix CTAP were performed in 11 and 20 adult patients, respectively, with 200 mL of contrast material (300 mg of iodine per milliliter) injected at a rate of 3 mL/sec via the superior mesenteric artery. Scanning delays were adjusted for single-helix CTAP so the last scan was obtained at 66 seconds. Delays were adjusted for double-helix CTAP so the last scan during the first helix (CTAP-1) was obtained 10 seconds before the end of the injection at 56 seconds and the first scan during the second helix (CTAP-2) was obtained at the end of the injection at 66 seconds. RESULTS: Single-helix CTAP scans were of poor quality owing to multiple perfusion abnormalities. Lesion detection for double-helix CTAP-1 was 93.2% and was 100% for CTAP-2, and CTAP-2 scans had significantly fewer perfusion abnormalities. CONCLUSION: A scanning delay of 60-66 seconds appears to be optimal. The CTAP-1 scans showed no useful information and need not be acquired.
Carcinoma, Hepatocellular↗
Hepatic arterial anatomy in transplantation candidates: evaluation with three-dimensional CT arteriography.
PURPOSE: To assess the utility of three-dimensional (3D) hepatic helical computed tomographic (CT) arteriography as a replacement for conventional angiography in the evaluation of the arterial anatomy of patients being considered for liver transplantation. MATERIALS AND METHODS: Three-dimensional CT arteriograms were obtained in 115 patients. Seventeen patients also underwent conventional angiography, and 16 patients who did not undergo angiography underwent hepatic transplantation. RESULTS: Among the 3D CT arteriograms, 106 delineated the major arteries that supplied the liver. Nine were considered technical failures. In the 17 patients with angiographic correlation, there was only one marked disagreement with 3D CT arteriography. In the 16 patients with surgical correlation, no marked discrepancies were found. CONCLUSION: In transplantation candidates, successful 3D CT arteriography was as accurate as angiography in the assessment of hepatic arterial anatomy. It was also safer, more convenient, and more easily tolerated. Conventional CT plus 3D CT arteriography was only 25% as expensive as the cost of conventional CT and conventional angiography.
Adult↗
Hepatic helical CT: effect of reduction of iodine dose of intravenous contrast material on hepatic contrast enhancement.
PURPOSE: To evaluate the effect of a reduction in iodine dose by altering volume and/or concentration of contrast material on hepatic contrast enhancement (HCE) values during hepatic helical computed tomography (CT). MATERIALS AND METHODS: One hundred eleven patients were randomized into four contrast material protocols according to concentration (in milligrams of iodine per milliliter)/volume (in milliliters)/grams of iodine: group 1, ioversol, 320/150/48; group 2, ioversol, 320/100/32; group 3, iohexol, 300/150/45; group 4, ioversol, 300/100/30. Helical CT protocols were identical for the four groups. Time-attenuation curves were constructed; the mean HCE, contrast enhancement index (CEI), and optimal liver scanning interval (OLSI) were calculated; and the results were compared statistically. RESULTS;: Time-attenuation curves, mean HCE, CEI, and OLSI of groups 1 and 3 were significantly superior to those for groups 2 and 4. Decrease in volume from 150 to 100 mliters decreased mean HCE by 27%, CEI by 69%, and OLSI from 80%-100% to 0%-43% at threshold levels of 40-60 HU. CONCLUSION: Decrease in iodine dose from 45-48 g to 30-32 g significantly decreases all HCE values, which potentially decreases detection of focal hypovascular hepatic lesions.
Adult↗
Renal perfusion: pharmacologic changes depicted with power Doppler US in an animal model.
PURPOSE: To evaluate the ability of power Doppler ultrasonography to depict changes in renal perfusion after pharmacologic manipulations. MATERIALS AND METHODS: Six domestic swine were intubated and anesthetized. The right renal artery was catheterized for injection of epinephrine (100 micrograms) and papaverine (2 mg/kg). Intraarterial blood pressure, heart rate, and oxygen saturation were measured continuously. Longitudinal images of the kidney were obtained, and the power Doppler color map was analyzed subjectively and by computer at baseline and at the time of maximum drug effect. RESULTS: Epinephrine produced vasoconstriction with a diminished power Doppler color map and a decrease in both subjective and computer scores. After papaverine-induced vasodilatation, the power Doppler map was enhanced, as reflected by increased subjective and computer scores. CONCLUSION: The power Doppler color map reflects anticipated changes in renal perfusion after alterations in blood flow by vasoactive drugs.
Animals↗
Evaluation of the portal venous system before liver transplantation: value of phase-contrast MR angiography.
OBJECTIVE: The purpose of this study was to assess the accuracy of phase-contrast MR angiography with gadolinium in evaluating the patency and blood flow direction of the portal venous system; the presence, extent, and type of varices; and the patency of surgical decompressive shunts in patients before liver transplantation. This information is essential in management and care of patients with chronic liver disease and portal hypertension and those who are candidates for liver transplantation. SUBJECTS AND METHODS: Twenty-four patients with portal venous hypertension were evaluated with phase-contrast MR angiography. Two patients had surgical splenorenal shunts and one had a mesocaval shunt. Phase-contrast angiograms were acquired as a series of two-dimensional sequential coronal sections during breath-holding and after IV administration of gadopentetate dimeglumine. Correlative findings from color flow Doppler sonography, contrast-enhanced CT scanning, and conventional angiography were available in 23, 20, and 10 patients, respectively, and were used as standards. The images from each technique were analyzed independently for patency of and flow direction in the portal vein, splenic vein, superior mesenteric vein, and surgically created shunts, and for detection, distribution, and extent of five variceal groups. RESULTS: Findings from phase-contrast MR angiography completely agreed with those of sonography, CT scanning, and conventional angiography. The main portal vein was patent in 18 patients, stenosed in one, partially thrombosed in one, and occluded in four. Phase-contrast MR angiography correctly showed hepatofugal flow in three patients and hepatopetal flow in 17 patients. Both the splenic and superior mesenteric veins were patent in 20, partially thrombosed in one, and occluded in three cases. Phase-contrast MR angiograms showed 85% of the variceal groups, and MR rating of variceal size was not significantly different from that of CT rating. Phase-contrast MR angiography correctly showed the patency of all three surgical decompressive shunts. CONCLUSION: Phase-contrast MR angiography is accurate for evaluating the patency and flow direction of the portal venous system, detecting and determining the distribution and extent of varices, and assessing the patency of surgically created shunts. Therefore, it is a reliable and noninvasive technique that can provide crucial information in the preoperative workup of liver transplant recipients.
Adult↗