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.

Percutaneous transhepatic drainage. Risks and benefits.

We evaluated the risks and benefits of percutaneous transhepatic biliary drainage (PTD) in 44 patients. Patients were divided into two groups, palliative and preoperative, each of which had 22 patients. Major complications included bacteremia, hemobilia, and liver abscess and occurred in ten patients (23%). A liver abscess along the catheter tract may have contributed to the death of one patient with an advanced malignant neoplasm. Major complications were more likely to develop in palliative-group patients (36% v 9%) and those patients were more likely to die within 30 days of the procedure (27% v 0%). Four (57%) of seven palliative-group patients and none of six preoperative-group patients with pre-PTD bilirubin levels higher than 20 mg/dL died within 30 days after PTD. Liver function test results improved within seven days in approximately 85% of the patients. Twenty-one patients (95%) in the preoperative group survived surgery. We concluded that the risk of PTD may outweigh the benefit in the subset of patients with advanced malignant neoplasms and a bilirubin level higher than 20 mg/dL. Even then, however, PTD may be justified if pruritus is incapacitating. Pending results of further randomized trials, we have continued performing PTD preoperatively in patients whose bilirubin levels exceed 10 mg/dL.

Iatrogenically induced cortical blindness associated with leptomeningeal enhancement.

Leptomeningeal enhancement is usually infective or neoplastic in origin. We present a case in which a patient received total parenteral nutrition via a catheter unknowingly placed within the right vertebral artery. We postulate that the hyperosmolar nature of the infused solution induced temporary osmotic disruption of the blood-brain barrier, resulting in cortical blindness associated with localized leptomeningeal enhancement.

Diagnostic effects of edge sharpening filtration and magnification on digitally subtracted renal images.

The improved appearance of digital radiographs filtered to improve local contrast and sharpen edges has not increased acceptance of these images by radiologists. Furthermore, many radiologists assert that correct diagnosis is not improved with these filtered images. This study was designed to test this assertion for digital subtraction angiograms (DSA) of renal images. Four experiments are described. First, phantom studies identified filters and their parameters thought likely to be acceptable and useful in diagnosing renal images formed by DSA. Second, these filters and parameters were then tested on medical images to assess their acceptance by radiologists. Third, display modes of windowing, positive/negative presentation, and magnification were varied for filtered and unfiltered images to assess preferences of radiologists. Fourth, filtered and unfiltered magnified images were used to test improved diagnosis. In the final experiment, 148 images from 33 renal studies (15 normal, 18 abnormal) were magnified, gray level windowed, and filtered. Diagnosis was not improved by the two edge sharpening filters tested.

Multiple endocrine neoplasia type I. A case report.

A case of multiple endocrine neoplasia (Men) consisting of an unusual combination of an insulin-producing islet cell tumour and an adrenal adenoma is reported. CT clearly demonstrated the adrenal mass whereas the pancreatic lesion remained questionable. Conversely angiography located the pancreatic tumour but the adrenal findings were subtle.

Transarterial chemoembolization is a safe treatment for unresectable hepatic malignancies.

Acute liver failure has been reported as a frequent complication of transarterial chemoembolization (TACE). We prospectively evaluated the adverse effects and biochemical changes of TACE. From 10/95 to 9/96, 35 patients with hepatic malignancies were evaluated for TACE. Fifteen patients (9 male and 6 female) received 23 treatments. Ten of 15 patients had hepatocellular carcinoma, and 5 had metastatic tumors. Treatment exclusion criteria included advanced liver disease, hepatic vascular thrombosis, and severe comorbidity. TACE consisted of intra-arterial infusion of a mixture of doxorubicin, cisplatin, and mitomycin followed by embolization. Clinical symptoms and laboratory studies were monitored following treatment. Technical success was achieved in all patients. Adverse symptoms were transient, and most resolved within 1 week. Changes in hepatic, renal, and hematologic function were temporary and returned to pre-TACE levels by 1 month. None developed acute liver failure. The mean hospital stay was 3 days. Ten of 13 patients had a significant decrease in baseline tumor markers. The actual survival was 93 per cent with a median follow-up of 10 months. TACE can be performed safely in patients with hepatic tumors. The adverse effects can be anticipated and easily managed.

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.

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.

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.

Blood flow determinations utilizing digital densitometry.

A method of obtaining relative and absolute blood flow measurements from digital densitometry was evaluated with a simulated vessel phantom and a hydrodynamic model. A digital vascular imaging system capable of acquisition in 512(2) and 1024(2) mode was used. Relative and absolute blood flow were measured using parameters derived from the densitometric curve. Since application of densitometric data to absolute flow measurements requires the vessel diameter, an algorithm for vessel size determination was created. Gray scale changes were demonstrated to be linearly related to contrast concentration. The variance of vessel size determination was significantly different in all combinations of 1024(2) and 512(2) imaging with 15 cm or 35 cm field size. The error in vessel size determination was significantly less using the larger 1024(2) matrix and the smaller 15 cm image intensifier field size, as shown by the smaller variance. In relative flow determinations, there was good correlation between the flow and four parameters of the densitometric curve with no significant differences between 512(2) and 1024(2) imaging. Absolute flow determinations had slightly lower correlation to actual flow but were not significantly different from relative flow determinations. Relative and absolute blood flow determinations can be performed adequately with either 512(2) or 1024(2) imaging. The increased accuracy in vessel size determination with 1024(2) imaging makes this high resolution system potentially preferable to determine absolute blood flow.

Unusual pulmonary angiographic findings in suspected pulmonary embolism.

Pulmonary arteriography is most commonly performed to diagnose pulmonary embolism. A variety of clinical entities, however, may mimic pulmonary embolism both clinically and scintigraphically. Five patients with abnormal pulmonary arteriograms resulting from diseases other than pulmonary embolism are presented. The clinical, radiographic, and pathologic findings and long-term follow-up in these patients are described. Awareness of the angiographic patterns seen in these unusual cases is important in the differential diagnosis of pulmonary thromboembolism.

Angiography of nonneoplastic retroperitoneal masses.

Although noninvasive imaging modalities can be used to initially detect retroperitoneal masses, angiography is still desirable for several reasons in those cases in which surgery is contemplated. The latter can forewarn the surgeon as to possible hemorrhagic complications in highly vascular lesions. In some cases it can predict the malignant potential of the lesion. Finally, since these masses may derive blood supply from multiple sources, a vascular "road map" is provided to the surgeon. The angiographic findings of malignant retroperitoneal tumors are well known, but very little has been published dealing with benign nonneoplastic retroperitoneal masses. We have performed angiography in 11 surgically proven nonneoplastic retroperitoneal masses (9 inflammatory lesions, 2 hematomas). Major arterial or renal displacement occurred in 10. The 2 hematomas and 3 inflammatory lesions were totally avascular; 6 of the 9 inflammatory lesions revealed fine neovascularity and 5 of these 6 had an associated capillary blush. Sources of vascular supply included the lumbar, renal capsular, superior mesenteric, and gastroduodenal arteries. Although angiography is helpful in preoperative evaluation of retroperitoneal masses for the aforementioned reasons, it may be difficult or impossible to differentiate benign from malignant lesions based on the angiographic findings alone.

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.

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.

Angiography of histopathologic variants of synovial sarcoma.

Synovial sarcomas are rare soft tissue tumors which histopathologically can be divided into monophasic, biphasic and mixed variants. As part of a protocol for intra-arterial chemotherapy 12 patients with biopsy proven synovial sarcoma underwent angiography. The angiograms on these patients were reviewed to determine whether synovial sarcomas and their variants demonstrated a characteristic angiographic appearance. Synovial sarcomas appeared angiographically as soft tissue masses which showed a fine network of tumor vessels with an inhomogeneous capillary blush. Their degree of vascularity varied according to their histopathology. Monophasic synovial sarcomas demonstrated in general a higher degree of neovascularity than the biphasic form. This finding was also suggested by histopathologic analysis of the vessels in the tumor. Although angiography did not show a distinctive vascular pattern it may be useful to evaluate tumor size and vascularity.

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.

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.

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.