Biomedical subjects

A S Gomes

Publications and source records attributed to A S Gomes.

At least 19 recordsLinked to original sources

PubMed1996

MR angiography for mapping potential central venous access sites in patients with advanced venous occlusive disease.

OBJECTIVE: Patients who depend on long-term central venous catheter support frequently develop thrombi in central veins. An accurate, noninvasive technique is needed to find patent central veins for future access. We evaluated the suitability of MR angiography for this use. SUBJECTS AND METHODS: Using five healthy volunteers and 19 patients who had malfunctioning central venous catheters and a history of central venous occlusive disease, we tested the ability of MR angiography to assess central vein status. Three radiologists experienced in MR angiography blindly interpreted both source images and three-dimensional reconstructed images. RESULTS: In the volunteers, MR angiography provided diagnostic-quality images of the internal and external jugular, innominate, subclavian, axillary, femoral, and iliac veins, and of the superior and inferior venae cavae. Interobserver interpretations did not vary. In the patients, MR angiography of venous patency was confirmed by venography in 27 segments, by sonography n 32 segments, and by attempted line placement in 21 placements. Images were diagnostically adequate in 206 of 216 segments (95%). For detection of occlusion, sensitivity was 97% and specificity was 94%. MR angiography predicted 100% of successful line placements and 80% of failures. Interobserver interpretations varied by 44%. MR angiography directly influenced therapy in 19 of 21 studies. CONCLUSION: We conclude that MR angiography provides risk-free, thorough, relatively accurate, and clinically useful assessment of most available central venous access sites, although interpretation may prove difficult in patients with extensive occlusions because of complex collateral drainage patterns.

Adolescent↗

PubMed1995

Multicenter trial to evaluate vascular magnetic resonance angiography of the lower extremity. American College of Radiology Rapid Technology Assessment Group.

OBJECTIVES: To assess the value of magnetic resonance angiography (MRA) in presurgical evaluation of patients with severe lower limb atherosclerotic occlusive disease and to assess the feasibility of rapidly conducting rigorous technology assessment. DESIGN: Blinded, prospective study of consecutive patients with signs or symptoms of severe infrainguinal peripheral vascular disease who were candidates for percutaneous or surgical intervention. Using both descriptive statistics and multivariate logistic analyses, MRA was compared with contrast arteriography (CA) (the current technique) for imaging 15 arterial segments of the leg and foot. Intraoperative contrast angiography was the "gold" standard. Also studied was the effect of adding MRA to the information used in planning treatment. SETTING: Six US hospitals, one a community hospital. PATIENTS: A total of 155; 84% with either rest pain or tissue loss. RESULTS: Sensitivity in distinguishing patent segments from completely occluded segments was 83% for CA and 85% for MRA; both had 81% specificity. For distinguishing near-normal segments (suitable as bypass graft termini), CA was less sensitive than MRA (77% vs 82%), but more specific (92% vs 84%). After adjusting for same-reader effects, odds of correctly distinguishing patent segments were 1.6 times as great for MRA as for CA (P < .01); for distinguishing near-normal segments, the odds for CA were 1.5 times as great as for MRA (P < .05). The addition of MRA changed the treatment plan in 13% of patients; in 86% of these cases, the surgery actually performed indicated that the MRA-inclusive plan was superior. CONCLUSIONS: Individually, MRA and CA are approximately equivalent in diagnostic accuracy. The addition of MRA to treatment plans based only on CA and other diagnostic information clearly improves the plans. Completed in 15 months (as planned), our study demonstrates the feasibility of conducting rigorous technology assessment rapidly enough to be timely even in fields in which diagnostic and treatment techniques are rapidly changing.

Adult↗

PubMed1994

Embolization therapy of congenital arteriovenous malformations: use of alternate approaches.

PURPOSE: To present results of embolization therapy performed with use of alternate approaches in 22 patients with peripheral congenital vascular malformations in whom lesion anatomy precluded effective use of conventional transfemoral catheter techniques. MATERIALS AND METHODS: Eleven patients had high-flow fistulous arteriovenous malformations and 11 had hemangiomatous vascular malformations. The alternate approaches employed were direct injection of embolic materials into the malformation or into central vessels of the lesion under fluoroscopic guidance and (in four cases) selective catheterization and embolization of abnormal veins draining arteriovenous malformations. The primary embolic agent combination used consisted of polyvinyl alcohol particles, sodium tetradecyl sulfate, microfibrillar collagen, and ethanol. RESULTS: Use of alternate approaches resulted in effective symptomatic control in 10 of 11 patients (91%) with hemangiomatous lesions and seven of 11 (64%) with high-flow arteriovenous malformations. CONCLUSION: Use of alternate approaches to such vascular malformations extends the use of embolization therapy.

Adult↗

PubMed1992

Biliary strictures complicating liver transplantation. Incidence, pathogenesis, management, and outcome.

Six hundred sixty-six patients received 792 liver transplants between February 1, 1984 and September 30, 1991. Biliary reconstruction was by choledochocholedochostomy (CDCD) with T-tube (n = 509) or Roux-en-Y choledochojejunostomy (CDJ) (n = 283). Twenty-five patients (4%) developed biliary strictures. Anastomotic strictures were more common after CDJ (n = 10, 3.5%) than for CDCD (n = 3, 0.6%). Intrahepatic strictures developed in 12 patients. Six patients had occult hepatic artery thrombosis (HAT). The other six patients received grafts in which cold ischemia time exceeded 12 hours. Anastomotic strictures were successfully managed by percutaneous dilation (PD) in five patients (n = 10), operation in three (n = 6), with retransplantation required in two patients. Intrahepatic strictures were managed by PD in seven, retransplantation in one, and expectantly in four patients. Of 25 patients, 19 (76%) are alive with good graft function. In three of six deaths, the biliary stricture was a significant factor to the development of sepsis and allograft failure. The authors conclude that (1) anastomotic strictures are rare after LT; (2) the development of biliary strictures may signify occult HAT; (3) PD is effective for most strictures; and (4) extended cold graft ischemia (less than 12 hours) may be injurious to the biliary epithelium, resulting in intrahepatic stricture formation.

Adult↗

PubMed1992

Magnetic resonance angiography.

Literature of the past year contains several worthwhile papers describing the application of MR angiography techniques to imaging of the vascular system. MR angiography has been performed with two-dimensional time-of-flight, two-dimensional phase-contrast, and three-dimensional time-of-flight techniques. With current methodology it appears that a variety of MR angiography techniques are necessary to image the various vascular beds of the vascular system, with the appropriate MR angiography technique determined by the velocity and flow characteristics of the vascular bed of interest. Knowledge of the change in velocity patterns in disease states appears necessary for appropriate pulse sequence selection. Signal loss due to higher motion disorders remains problematic; however, the steady progress in MR angiography techniques suggests that these limitations will be overcome. Efforts are also underway to measure the velocity of blood flow. The potential combination of imaging and functional capabilities makes it likely that MR angiography will be an important technique for assessing the vascular system.

Blood Flow Velocity↗

PubMed1991

Diagnosis of portal vein thrombosis: value of color Doppler imaging.

This study was undertaken to determine the accuracy of color Doppler imaging in the diagnosis of portal vein thrombosis. Two hundred fifteen patients were studied with color Doppler imaging to determine patency of the main portal vein. Sonographic findings were confirmed in 75 patients, aged 19 to 66 years. Correlation with angiography was obtained in 13 patients, and surgical correlation was obtained in the remaining 62. Nine patients had portal vein thrombosis on the basis of these gold standards. Sonograms were classified as showing either patency or thrombosis, depending on the ability to show color flow within the main portal vein. Agreement between sonography and angiography or surgery was found in 69 patients (61 patent, eight thrombosed). One patient with a patent portal vein at sonography was found to have a thrombosed vessel at surgery, whereas five patients without portal venous flow at sonography had patent vessels at angiography (one patient) or surgery (four patients). Overall sensitivity and specificity for detection of portal vein thrombosis were 89% and 92%, with an accuracy of 92%, a false-negative rate of 0.11, a negative predictive value of 0.98, and a positive predictive value of 0.62. We postulate that the majority of errors in our study occurred in vessels that, although patent, had only sluggish flow, which could not be resolved because of technical limitations. We conclude that color Doppler imaging is a valuable screening procedure for the assessment of portal vein patency. If the sonogram shows a patent portal vein, no further studies are required. However, a lack of demonstrable flow does not always indicate thrombosis, and other imaging studies should be performed for confirmation.

Adult↗

PubMed1990

Massive splenomegaly. Superior results with a combined endovascular and operative approach.

Splenectomy for massive splenomegaly (drained splenic weight, greater than 1000 g) has an uncommonly high morbidity and mortality because of technical challenges and problems of hemostasis. In a group of 10 patients with massive splenomegaly due to myeloproliferative disorders (average splenic weight, 4193 g), we developed a management algorithm based on preoperative angiographic embolization of the splenic artery. Average operating time was 1.7 hours (range, 1 to 2.5 hours). Average blood loss was 528 mL; six of the 10 patients had blood loss less than 250 mL. There were four minor complications and one major complication (gastric ulcer requiring reoperation). There were no deaths in the perioperative period, and no patients required reoperation for hemorrhage.

Adult↗

PubMed1990

Pulmonary arteries: MR imaging in patients with congenital obstruction of the right ventricular outflow tract.

Thirty-five patients with congenital obstruction of the right ventricular outflow tract underwent magnetic resonance (MR) imaging for evaluation of the pulmonary arteries. All patients underwent cardiac catheterization, and 33 underwent two-dimensional Doppler echocardiography. Results of the three imaging studies were compared. With regard to the presence of a pulmonary confluence, results of MR imaging and angiography were in agreement in 31 of the 35 patients (89%), results of echocardiography and MR imaging were in agreement in 27 of 33 patients (82%), and results of echocardiography and angiography were in agreement in 27 of 33 patients (82%). There was good correlation of measurements of main pulmonary artery size among all three methods and of right and left pulmonary artery size obtained at MR imaging and angiography. Echocardiographic measurements of right and left pulmonary artery size correlated poorly with those obtained at MR imaging and angiography. Results indicated that MR imaging is useful in evaluating the pulmonary arteries in patients with congenital heart disease.

Angiography↗

PubMed1990

MR imaging of the bird's nest filter.

The appearance of the Bird's Nest inferior vena cava filter on magnetic resonance (MR) images of 11 patients is described. No complication or symptomatic filter displacement was encountered as a result of MR imaging performed at 1.5 T. The filters created significant local artifact and distortion on MR images. However, diagnostic MR images of the pelvis, spine, and brain may still be obtained.

Adult↗

PubMed1990

Color Doppler imaging of portosystemic shunts.

This study was designed to investigate the utility of color Doppler sonography in the evaluation of portosystemic shunts. Thirty-one patients with a total of 32 shunts were imaged. The types of shunts examined included portacaval, five; mesocaval, eight; distal splenorenal (Warren), 14; and mesoatrial, five. Sonography was performed without knowledge of the status of the shunt, although the type of shunt was known before beginning the study. The sonographic studies were evaluated to determine their sensitivity and specificity on the basis of a prospective comparison with angiography or MR imaging (22 cases). The possible advantages of color Doppler over duplex Doppler sonography in evaluating portosystemic shunts were also investigated, as was the ability of color Doppler sonography to image specifically the shunt anastomoses. Color Doppler sonography successfully inferred shunt patency (17 cases) or thrombosis (five cases) in all 22 shunts for which correlative imaging was available (sensitivity = 100%, specificity = 100%). In comparing duplex with color Doppler sonography in all 32 shunts, the two techniques were almost equally effective in establishing patency in portacaval, mesocaval, and mesoatrial shunts. Duplex Doppler sonography, however, provided useful diagnostic information in only four of 14 splenorenal shunts. Color Doppler correctly inferred patency or thrombosis in all 14. Among all 32 shunts, the anastomosis was shown clearly by color Doppler in 23, probably in four, and not all in five. Our results suggest that color Doppler sonography is an excellent method for the evaluation of all varieties of surgically created portosystemic shunts. In particular, color Doppler sonography appears to be superior to duplex Doppler sonography in imaging splenorenal communications.

Adolescent↗

PubMed1990

Comparison of Biello, McNeil, and PIOPED criteria for the diagnosis of pulmonary emboli on lung scans.

The McNeil, Biello, and newly proposed PIOPED (from the National Institutes of Health-sponsored study, Prospective Investigation of Pulmonary Embolism Detection) interpretive methods for detection of pulmonary embolism on lung scans were compared in 96 patients who also underwent pulmonary angiography. Segmental findings on 99mTc perfusion and aerosol ventilation scans, chest radiographs, and pulmonary angiograms obtained within 48 hr of each other were encoded along with other information into a data base to facilitate analysis. The McNeil, Biello, and PIOPED criteria were applied to the encoded data. Although the PIOPED set of criteria yielded the most favorable likelihood ratio for predicting an angiogram showing pulmonary emboli and a favorable likelihood ratio for predicting an angiogram not showing pulmonary emboli, it had the highest number of indeterminate studies. The McNeil criteria demonstrated the least favorable likelihood for predicting pulmonary emboli on an angiogram. The Biello and McNeil criteria showed the most favorable likelihood ratio for predicting an angiogram not showing pulmonary emboli. Analysis of receiver-operating-characteristic (ROC) curves yielded the greatest area under the ROC curve for the Biello criteria, but there were no statistically significant differences among the three sets of criteria. This study suggests that the Biello scheme represents the best compromise of the sets of criteria studied.

Angiography↗

PubMed1989

Acute renal dysfunction in high-risk patients after angiography: comparison of ionic and nonionic contrast media.

A group of 145 high-risk patients who underwent angiography after administration of the nonionic contrast agent iohexol were monitored for the development of acute renal dysfunction. The results in this group were compared with those in 202 high-risk historical control subjects who had undergone angiography after administration of ionic contrast material. All patients in both groups received similar pre- and postangiographic treatment. A greater number of patients in the ionic group had preexisting renal disease, were of advanced age, and had received large volumes of contrast material. Acute renal dysfunction occurred in 20 of the 202 (10%) patients in the ionic group, compared with eight of the 145 (5.5%) patients in the nonionic group; this difference is not statistically significant. Five patients in the ionic group, but none of the patients in the nonionic group, ultimately required dialysis; this difference is not statistically significant. The findings suggest that a randomized trial in high-risk patients should be undertaken before a clinical advantage of the nonionic contrast agent iohexol with regard to renal function can be assumed.

Acute Kidney Injury↗

PubMed1989

Budd-Chiari syndrome: treatment with percutaneous transhepatic recanalization and dilation.

The authors describe a child with Budd-Chiari syndrome secondary to membranous obstruction of the hepatic veins and a web in the inferior vena cava. Transhepatic catheter venography demonstrated the occlusion, which was recanalized and dilated percutaneously via a transhepatic approach. Hepatomegaly and ascites decreased promptly and the prothrombin time became normal.

Angioplasty, Balloon↗

PubMed1989

MR imaging of congenital anomalies of the thoracic aorta and pulmonary arteries.

MR imaging has rapidly assumed an important role in the diagnosis of congenital anomalies of the aortic arch and pulmonary arteries. Because it is noninvasive and does not involve the use of ionizing radiation, it is particularly useful in children and in clinical settings that require serial follow-up studies, such as in patients with aortic aneurysm and in postoperative patients. In the evaluation of the pulmonary arteries of patients with pulmonary artery or right ventricular outflow tract obstructive lesions, MR imaging has become a frequently used noninvasive imaging technique for determining pulmonary artery configuration and for monitoring pulmonary artery growth. The large field of view and high-quality images afforded by MR imaging make it a useful diagnostic tool that can supplement, confirm, and in some instances supplant the use of other conventional imaging techniques.

Aorta, Thoracic↗

PubMed1988

Systemic-to-pulmonary collateral vessels and shunts: treatment with embolization.

Abnormal collateral vessels develop frequently in patients with right ventricular outflow or pulmonary artery obstruction. Surgery is usually used to obliterate these vessels but may be difficult, involve prolonged operative time, or require a different thoracotomy than that used for correction or palliation of the cardiac anomaly. Sixteen trans-catheter embolization procedures were performed in 15 patients with systemic-to-pulmonary collateral vessels and shunts. In eight embolization procedures performed because of congestive heart failure or low oxygenation, clinical improvement was obtained in seven. In all six patients who underwent embolization preoperatively, the outcome of surgical correction or palliation was satisfactory. Hemorrhage ceased in the two patients with hemoptysis. There were two complications, one transient loss of femoral pulse and one segmental pulmonary infarction. Embolization is a useful adjunct to surgery and medical management of patients with systemic-to-pulmonary collateral vessels and shunts.

Adolescent↗

PubMed1987

Magnetic resonance imaging of the thoracic aorta.

Forty-one patients with a variety of suspected aortic lesions underwent magnetic resonance imaging (MRI) of the thoracic aorta. Patients were separated into 2 groups: Group A included 19 patients who underwent MRI after arteriography for comparison purposes and were evaluated retrospectively. Surgical confirmation was obtained in 9 of these patients. Group B included 22 patients who were studied prospectively because of abnormal chest x-ray, ultrasound or computerized tomographic findings and did not undergo arteriography before MRI. Two patients from this group had surgery. In group A, MRI correlated with the surgical or angiographic findings in 18 of 19 patients (95%). In group B, MRI was considered of diagnostic quality in all patients and no other invasive or noninvasive imaging modalities were needed for diagnosis and treatment. Thus, MRI will replace arteriography in a large proportion of patients with suspected thoracic aortic lesions.

Aorta, Thoracic↗

PubMed1987

Observer variability with conventional and digital subtraction carotid angiograms.

A study was carried out to evaluate the intra- and inter-observer variability in the determination of the severity of carotid artery stenosis on conventional and digital subtraction angiograms. The primary goal was to compare the two types of contrast studies as "gold standards" for the evaluation of non-invasive tests. Linear regression analysis of the continuous variable of percentage stenosis yielded correlation coefficients from 0.90 to 0.99. Findings were also evaluated in terms of the discrete variables formed by dividing the lesions into five categories of stenosis: kappa analysis ranged from 0.53 to 0.91. Although the digital subtraction arteriograms had greater variability than conventional ones, careful measurement of the digital images can provide a reliable estimate of the degree of stenosis.

Adult↗

PubMed1987

Coronary artery bypass grafts: visualization with MR imaging.

To evaluate the use of magnetic resonance (MR) imaging in the detection of coronary artery bypass grafts (CABGs), 20 patients with grafts underwent electrocardiographic-gated MR study. The number and location of CABGs in each patient were not known at the time of study. The number of grafts seen with MR imaging was compared with the actual number of grafts determined from the operative or angiographic report. On the prospective review of the images, 54 of 64 grafts (84%) were detected, with three false-positive results. When the images were reevaluated with knowledge of the type and number of grafts in each patient, 56 of 64 grafts (88%) were detected. Forty-one of the 46 (89%) left grafts, 15 of the 18 (83%) right grafts, and five of the 11 (45%) internal mammary grafts were detected. Although resolution was not adequate to determine the presence of graft stenosis, this early experience indicates that patent CABGs can be seen with MR imaging.

Coronary Artery Bypass↗