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Biomedical subjects

J F Lois

Publications and source records attributed to J F Lois.

At least 19 recordsLinked to original sources
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↗
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↗
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

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↗
PubMed1987

Pulmonary arteriography: comparison of cough stimulation effects of diatrizoate and ioxaglate.

Twenty-five patients were observed in a prospective crossover study to determine whether the new low-osmolality contrast agents would be less prone than conventional agents to produce coughing during pulmonary arteriography. Selective left and right pulmonary arteriography (two views of each side) was performed with alternating administrations of diatrizoate sodium meglumine and ioxaglate sodium meglumine. Twenty-one patients had all four injections while four patients received injections on only one side. Sixteen of 25 patients coughed on at least one injection of diatrizoate, with three of these experiencing explosive coughing. One of 25 patients coughed with ioxaglate, and that was only minimally. This difference is statistically significant (P less than .001, on the basis of McNemar chi 2 test for paired data). When no coughing occurred, the quality of the diatrizoate and ioxaglate radiographs was indistinguishable. We conclude that ioxaglate is useful in pulmonary arteriography because of its lack of cough stimulation.

Adult↗
PubMed1987

Nonsurgical repositioning of central venous catheters.

Long-term central venous catheters are placed for total parenteral nutrition and/or chemotherapy. These catheters are placed surgically and fixed to the subcutaneous tissues. Complications include infection, venous thrombosis, and mechanical problems. The authors developed a method to percutaneously reposition displaced central venous catheters. The procedure is performed with fluoroscopy and modified angiographic techniques. Fifteen patients underwent a total of 17 procedures. The initial success rate was 76%; the final success rate was 88%. Many central venous catheters can be salvaged with this low-morbidity procedure, which negates the need for surgical intervention.

Angiography↗
PubMed1987

Congenital abnormalities of the aortic arch: MR imaging.

Thirty-four patients, 1 month to 63 years old, with known or suspected congenital abnormalities of the aortic arch underwent magnetic resonance (MR) imaging. Sixteen patients were studied retrospectively, 18 prospectively. In all retrospective studies, the aortic arch abnormality was seen with MR imaging. In the prospective studies, MR imaging enabled diagnosis in 15 of 18 (83%) patients. Twenty-nine of 34 patients underwent two-dimensional echocardiography; nine were studied retrospectively, 20 prospectively. In the prospective studies, echocardiography enabled diagnosis in 13 of 20 (65%) patients. Although two-dimensional echocardiography has a high sensitivity in the detection of aortic arch abnormalities in the neonate, arch abnormalities in the neonate, its sensitivity is lower in older children, adults, and postoperative patients. The authors' experience shows that MR imaging is an important, noninvasive modality in the evaluation of older children, adults, and postoperative patients with congenital aortic arch abnormalities.

Adolescent↗
PubMed1987

Risks of percutaneous transhepatic drainage in patients with cholangitis.

Percutaneous transhepatic biliary drainage (PTD) has been advocated as a method of achieving biliary decompression in patients with cholangitis. However, the risk of PTD in these patients has not been determined. Therefore, we reviewed the records of 95 consecutive PTD patients, 30 (32%) of whom had cholangitis. Forty-four (46%) of the 95 patients underwent PTD as a preoperative measure; the remaining 51 (54%) had PTD for palliation of end-stage malignancies. Thirty-day mortality and overall morbidity were 17% and 30%, respectively, in the patients with cholangitis and 15% and 28% in the patients without cholangitis. These differences were not statistically significant. However, patients with cholangitis had a significantly higher (p less than .05) incidence of post-PTD bacteremia. In patients undergoing PTD for palliation, both mortality (25%, p less than .01) and morbidity (35%) were higher than in those being drained preoperatively. This analysis suggests that PTD can be performed safely in patients with cholangitis and that the patient's underlying disease process is more important than the presence of cholangitis in determining the outcome.

Adolescent↗
PubMed1987

Cardiac tumors and thrombus: evaluation with MR imaging.

Thirty patients with a suspected cardiac or pericardial mass underwent MR imaging. Twenty-six also had two-dimensional (2D) echocardiography, and three also had CT; one patient had MR only. Overall, 18 (60%) of the 30 patients were found to have a mass lesion. The lesion was confirmed by biopsy, surgery, or unequivocal demonstration on CT, 2D echocardiography, and/or MR imaging. Fourteen of the lesions were soft-tissue or tumor masses, and four were thrombi. The findings on 2D echocardiography and MR were in agreement in 17 (65%) of 26 patients who had both studies. MR was equivocal or in error in two patients (7%), and 2D echocardiography was nondiagnostic in seven (27%). In all seven patients with equivocal 2D echocardiography, the diagnosis was made by MR. In the four patients who did not have 2D echocardiography, MR showed the mass clearly. MR imaging is useful in the diagnosis of cardiac mass lesions. It can be used effectively in addition to 2D echocardiography to increase the certainty of diagnosis, and it is useful when 2D echocardiography is equivocal or inadequate.

Adolescent↗
PubMed1986

Aortic dilation, dissection, and rupture in patients with Turner syndrome.

We report two patients with Turner syndrome who had aortic dissection and rupture, one with prior repair of coarctation. We also note the high incidence (8.8%) of unrecognized aortic root dilation in a group of 57 patients with Turner syndrome whom we prospectively evaluated by echocardiography. Our analysis and review of previously reported cases suggests that multiple risk factors may exist for aortic dissection, including coarctation, bicuspid aortic valve, and systemic hypertension, but that these need not be present. Aortic root dilation may be an additional finding that suggests the patient with Turner syndrome is also at risk. When it is present, magnetic resonance imaging visualizes the entire aorta and allows quantification of the site and degree of dilation. In patients with dissection, the aorta often exhibits pathologic evidence of cystic medial necrosis similar to the finding in patients with Marfan syndrome. Therapeutic methods to decrease risk, such as those directed toward prevention of bacterial endocarditis, blood pressure control, and perhaps prophylactic beta blockade or surgical reconstruction, may need to be considered. Patients with Turner syndrome, their families, and the physicians who care for them should be aware of the significance of unexplained chest pain, dyspnea, or hypotension as potential manifestations of aortic dissection or rupture.

Adolescent↗
PubMed1986

Digital subtraction angiography: a comparison of 512(2) and 1024(2) imaging.

A commercial DSA unit was modified by the manufacturer to permit 1024 X 1024 8-bit imaging. System upgrade includes a high-resolution 1049-line TV camera that operates with variable aperture to minimize x-ray exposure during 1024(2) imaging. To compare the change in resolution and radiation exposure between 512(2) and 1024(2) imaging with this system, a two-phase phantom study was performed using a high-contrast converging lead line phantom and a specially designed high-resolution low-contrast Lucite phantom. The two-phase phantom study tested general system resolution performance and resolution under simulated and actual clinical conditions for each field size (15, 25, and 36 cm). The 512(2) imaging was performed with the aperture reduced to the 512 setting; 1024(2) imaging was performed with the aperture at the 512 and 1024 values. The 1024(2) imaging resulted in only modest improvement in resolution compared to 512(2). While Nyquist limits were approached with 512(2) imaging, this was not the case with 1024(2) imaging. This suggests other factors such as system noise are playing a significant role in 1024(2) image degradation.

Angiography↗
PubMed1986

Angiographic treatment of gastrointestinal hemorrhage: comparison of vasopressin infusion and embolization.

The results of selective intraarterial vasopressin-infusion therapy and embolization therapy were compared in two groups of patients with major gastrointestinal hemorrhage. The site of bleeding, clinical course, complications, and transfusion requirements were evaluated in each group. Intraarterial vasopressin infusion therapy resulted in successful control of hemorrhage in 16 (70%) of 23 patients. Four patients, however, rebled and an operation was necessary, reducing the overall success rate to 52% (12 of 23). In the group treated with embolization therapy, primary success was achieved in 17 (71%) of 24 patients. Four patients in whom initial embolization failed to control bleeding underwent repeat embolization and in all four permanent control of hemorrhage was obtained, producing an overall success rate of 21 (88%) of 24. Analysis of our results according to site of hemorrhage suggests that at certain sites embolization is a preferred method of treatment; embolization allows earlier control of gastrointestinal hemorrhage and a reduction in transfusion requirements.

Adult↗
PubMed1986

Aortic mural thrombus: an occult source of arterial thromboembolism.

During a 28-year period from 1955 to 1983, two cases of massive repetitive arterial thromboembolism from nonaneurysmal aortic mural thrombus were diagnosed antemortem and successfully corrected at the University of California, Los Angeles Medical Center. Within the same time period, 48 cases of nonaneurysmal aortic mural thrombus were identified in 10,671 consecutive autopsies (0.45% incidence). Eight of these patients had evidence of distal embolization (17%), and three had major thromboembolic occlusions, which were considered the proximate cause of death (6%). The latter three patients represented 9% of autopsy-confirmed deaths from peripheral arterial thromboembolism. The diagnosis was established in a 49-year-old man and a 51-year-old woman after a long course marked by recurrent arterial embolization. Despite multiple evaluations, which included angiography, the diagnosis remained elusive until clinical suspicion resulted in complete biplane aortographic survey. Although the morphologic characteristics of this lesion are quite striking, subtle angiographic changes and lack of familiarity with the clinical presentation contribute to the difficulty and infrequency of diagnosis. This unique lesion comprises an important segment of the so-called cryptogenic sources of arterial embolization and can be corrected by a definitive surgical procedure.

Aorta, Abdominal↗
PubMed1985

Radiology and pathology of malignant fibrous histiocytomas of the soft tissues: a report of ten cases.

Malignant fibrous histiocytomas (MFH) are believed to originate from histiocytes and are composed of malignant cells with spindle or round shapes. We evaluated ten MFH of the soft tissues by plain roentgenograms, computed tomography (CT), and angiography and subdivided them into four grades of anaplasia and five predominant histologic variants. The variants of MFH demonstrated different vascular patterns. The extension of the lesions could be determined by CT and angiography. CT is the method of choice in the assessment of size and extent of MFH of the soft tissues. When intra-arterial chemotherapy is indicated the angiograms obtained at each catheter placement may substitute CT in follow-up studies obviating additional diagnostic procedures.

Adult↗