PubMed Health⌕ Search

Biomedical subjects

M R Fisher

Publications and source records attributed to M R Fisher.

At least 55 records · Page 3Linked to original sources
PubMed1985

Evaluation of the prone position in digital subtraction angiography of the kidneys.

In visualizing the kidneys and renal arteries, the digital subtraction angiography (DSA) image is degraded by peristalsis and overlying bowel gas. In 25 patients we evaluated the efficacy of the prone position to counter these technical difficulties and found that the prone position offers visualization superior to the supine, especially in obese and uncooperative patients and those with abundant bowel gas. We advocate that prone imaging be included routinely in renal DSA.

Adult↗
PubMed1985

Computed tomography in the evaluation of cirrhosis and portal hypertension.

Patients with cirrhosis present a continuing diagnostic and therapeutic challenge. The status of their disease frequently changes, necessitating intensive serial evaluation. CT is an invaluable tool in the management of these patients because it can noninvasively provide vital information concerning liver size, contour, and occasionally hepatic parenchyma. More importantly, CT can demonstrate superficial and deep varices, assess the patency of the extrahepatic portal system, and detect other complications including ascites, hepatic steatosis, hemochromatosis, and hepatocellular carcinoma.

Ascites↗
PubMed1985

Bone marrow imaging: magnetic resonance studies related to age and sex.

Measurements of T1 and T2 relaxation values and spin density of the lumbar vertebral bone marrow were performed in 212 patients, and the results were correlated with the patients' age and sex. T1 and T2 relaxation times for bone marrow in the lumbar vertebral bodies showed a progressive decrease with age for both sexes (except for the T2 relaxation values in female patients). The replacement of hematopoietic marrow by fatty marrow could explain the decrease in T1 and T2. The T1 and T2 values were in the same range for the first two age groups (age 1-10 years and age 21-40 years) and became slightly greater for the older female patients (age 51 years and older) than for the older males. This could be due to the loss of bone and mineral content, which is more rapid and significant for women. These normal T1 and T2 values may provide a baseline for future evaluation of diseases involving the lumbar spine.

Adolescent↗
PubMed1985

Abdominal venous system: assessment using MR.

Twenty-five patients with known or suspected evidence of venous disease based on results of computed tomography, angiography, or ultrasound were imaged with magnetic resonance (MR) to determine the MR characterization of venous abnormalities. MR findings were proved by laparotomy or autopsy in 18 of 25 cases. In seven of 25 patients in whom only biopsy was performed, the MR findings were correlated with findings from other radiologic tests. On MR, the inferior vena cava (IVC), portal vein, and their major tributaries were seen in all but two cases. In those two, identification of collaterals led to the correct diagnosis of splenic vein thrombosis in one case and left renal vein thrombosis in another. MR imaging helped identify intraluminal thrombi in the IVC (12 of 12 cases), portal vein (two of two cases), renal veins (seven of seven cases), superior mesenteric vein (one case), and iliac veins (seven of seven cases). Intraluminal signal intensity secondary to slow blood flow seen in five patients was always differentiated from the thrombus. MR imaging helped identify correctly the nature of the thrombus in 11 of 16 patients. In five patients, the differentiation between tumor thrombus and blood clot thrombus was not possible. Involvement of the IVC wall by tumor was seen in four cases. MR imaging also accurately depicted slow flow in obstructed or constricted veins; encasement, compression, or displacement of veins without intraluminal occlusions; and the presence of venous collaterals. The MR imaging evaluation of venous abnormalities is accurate, easily performed, and will probably become an important application.

Abdomen↗
PubMed1985

MR imaging using specialized coils.

The purpose of this study was to evaluate the clinical utility of specialized coils with magnetic resonance (MR) imaging and to determine the potential improvement in the signal-to-noise ratio (SNR) provided by the various coils. A total of 48 patients were studied-33 with surface coils and 15 with limb coils. MR imaging was performed with a superconducting magnet operating at 0.35 T. Two applications of surface coils were evaluated; one used for both transmitting and receiving and the other used only for receiving. Structures studied with the surface coils included the orbit, carotid artery, cervical and lumbar spine, parotid and thyroid glands, other neck structures, femoral artery, kidney, prostate, hip, and heart. The regions studied with the limb coil were the ankle, knee, wrist, elbow and popliteal artery. We calculated the SNR, and the results demonstrated a marked improvement with the specialized coils: a twofold increase for the 10-cm surface coil versus the head coil and a 4.6-fold increase compared with the body coil, a 2.3-fold increase for the 20-cm surface coil compared with the body coil, and 2.8- and 6.4-fold increases for the limb coil versus the head coil and the body coil, respectively. The use of specialized coils was feasible in the clinical setting and they provided a marked improvement in the image SNR, which facilitated the imaging of small and superficial structures.

Adolescent↗
PubMed1985

Urinary bladder MR imaging. Part I. Normal and benign conditions.

The normal urinary bladder and several benign entities of the bladder were examined in 50 patients by magnetic resonance (MR) imaging. Specific features assessed included appearance of the bladder wall, optimal repetition (TR) and echo delay (TE) parameters for bladder-wall demonstration, and differentiation among various benign abnormalities, including bladder-wall hypertrophy, inflammation, and mucosal congestion, on MR images. The bladder wall in the 30 healthy subjects was best displayed using a TR = 2 sec, TE = 56 msec image, which gave 60% contrast between the bladder wall and urine and 48% contrast between the bladder wall and fat. Demonstration of bladder-wall hypertrophy required similar imaging; bladder distention was necessary to demonstrate the thickness of the bladder wall. Congestion and inflammation were best demonstrated on TR = 2 sec, TE = 56 msec images, which gave 45% contrast. Normal and/or hypertrophic bladder wall were distinguished from inflammation and congestion on the basis of signal intensity variations and/or T1 and T2 relaxation parameters.

Adult↗
PubMed1985

Urinary bladder MR imaging. Part II. Neoplasm.

The potential of magnetic resonance (MR) imaging for the evaluation and staging of bladder tumors was analyzed in 15 patients (11 cases of transitional cell carcinoma, two adenocarcinomas, one leiomyosarcoma, and one leiomyoma). Neoplasms were characterized by size, site, and growth pattern, and the accuracy of the staging was compared with the results of computed tomography and pathologic study. Malignancies were accurately detected and staged by MR imaging in 12 of 14 patients (85%). Tumor site and degree of bladder distention did not adversely affect detection; tumors greater than 1.5 cm were detected easily. In situ carcinoma (stage Tis) was not detected on MR images. Imaging in both sagittal and transverse planes was needed for optimal bladder evaluation. Bladder carcinoma was best displayed with a short echo delay time (TE) of 28 msec and repetition (TR) times of 1.0-2.0 sec: TR = 1.0 gave 34% contrast and TR = 2.0 gave 36% contrast between tumor and surrounding urine. Bladder-wall invasion by tumor was best evaluated with long TR (2.0 sec) and long TE (56 msec) (82% contrast). For assessing tumor extension into perivesical fat, short TR (0.5 sec) and TE (28 msec) were optimal (58% contrast). MR imaging offers an increased sensitivity for tumor detection and promises to greatly improve the staging of bladder neoplasms.

Adult↗
PubMed1985

Roentgenographic and clinical staging of allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a disease of asthmatics that follows a protracted course. When ABPA is treated with high dose corticosteroids, it presents a difficult problem in clinical management. Five stages, based on clinical, roentgenographic, and immunologic criteria, have been identified as follows: (I) acute, (II) remission, (III) exacerbation, (IV) corticosteroid-dependent asthma, and (V) pulmonary fibrosis. We studied 24 ABPA patients actively followed for up to 11 years at our institution. We conclude that while there are no unique roentgenographic findings to define a particular stage, clinicoroentgenographic staging does aid in therapeutic management. Two major roentgenographic contributions are (1) to establish the diagnosis by demonstrating proximal bronchiectasis, and (2) to provide a baseline for an individual patient against which to monitor progressive changes and remissions.

Acute Disease↗
PubMed1985

Use of linear tomography to confirm the diagnosis of allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) has been recognized increasingly in the past few years. In minimal disease, plain chest films may be insensitive. Early detection of pulmonary involvement may help prevent irreversible damage to the lungs and bronchi. Bronchography, while both sensitive and specific, is not without hazard, particularly to the asthmatic patient. We evaluated the usefulness of linear tomography in confirming ABPA prior to initiation of corticosteroid therapy. We find that tomography is a simple, noninvasive instrument for detecting the presence of or proving the absence of the earliest manifestations of ABPA.

Adolescent↗
PubMed1985

Hepatic vascular anatomy on magnetic resonance imaging.

This study evaluated the ability of magnetic resonance imaging (MRI) to depict the hepatic vasculature and surgical anatomy of the liver using the transaxial, coronal, and sagittal planes. Retrospective analysis of the abdominal MRI examinations of 94 patients was performed. The spin-echo imaging technique was used to obtain transaxial images in all patients and coronal and sagittal sections in 35 of these patients. Overall, the hepatic vasculature was better delineated on the longer repetition rates (2000 msec TR) and the first echo images (28 msec TE). The inferior vena cava, right and middle hepatic veins, and main and right portal veins were seen in 100% of the cases in the transaxial plane. The left hepatic vein was seen in 98%, the left portal vein in 93%, and the hepatic artery in 44% in the transaxial plane. In the sagittal and coronal planes, the inferior vena cava and main and right portal veins were seen in 100% of cases. The other hepatic vasculature was less frequently demonstrated. In the sagittal plane, the right hepatic vein was seen in 85% of the cases, the left hepatic vein in 62%, the middle hepatic vein in 90%, the left portal vein in 90%, and the hepatic artery in 14%. In the coronal plane, the right hepatic vein was seen in 85% of cases, the left hepatic vein in 14%, the middle hepatic vein in 79%, the left portal vein in 71%, and the hepatic artery in 7%. These results are from preliminary work. Further developments with MRI technology may render better visualization of hepatic vasculature.

Hepatic Artery↗
PubMed1985

Magnetic resonance imaging in the evaluation of abscesses.

Ten patients with percutaneous biopsy or surgically proven abscesses were evaluated with magnetic resonance imaging (MRI) to describe the appearance of abscesses, define the capability of MRI to localize abscesses, and compare the capabilities of MRI and CT for the diagnosis and determination of the extent of an abscess. Comparative CT scans were available in six cases. The most common MRI finding was an abnormal area of low signal intensity, either homogeneous or heterogeneous, on the short repetition rate (500 msec TR) images with a relative increase in signal intensity on the longer repetition rate (1500 or 2000 msec TR) images. MRI demonstrated a more clear delineation of the extent of inflammatory changes than did CT, and MRI demonstrated the abscess as a collection distinct from surrounding structures on at least one repetition rate. Intravenous contrast medium was unnecessary with MRI to evaluate vasculature or to define the capsule around an abscess. With CT, unless an abscess contained air or was of low attenuation, it often blended with the surrounding structures and was difficult to differentiate from them. Surgical clips in the postoperative patient with an abscess did not degrade the MR images as often occurred with CT. This study describes the MRI appearance of abscess and indicates a potential value of the use of MRI to evaluate abscess outside the central nervous system and spine.

Abdomen↗
PubMed1985

Multiphasic cardiac magnetic resonance imaging: normal regional left ventricular wall thickening.

Magnetic resonance imaging (MRI) is a completely noninvasive method for visualizing cardiovascular anatomy but has had limited use for assessment of cardiac function. The authors evaluated the use of gated MRI for the quantification of regional myocardial contraction. Nine normal subjects underwent gated MRI of five transverse sections (7 mm thickness) through the left ventricle at five intervals in the cardiac cycle using a new technique called rotating gated sequence. All five sections were examined, and the section that best demonstrated the midportion of the left ventricle in its maximum dimension was used to obtain measurement. This technique permitted assessment of regional wall thickening of various regions of the left ventricle in different phases of the cardiac cycle. The extent and percentage of wall thickening were calculated from measurements of the septum and anterior and lateral left ventricular wall in end-diastole and end-systole. The calculated mean values for extent and percentage of wall thickening for the septum were 0.40 cm and 40%; for the anterior wall, 0.61 cm and 73%; and for the lateral wall, 0.53 cm and 57%, respectively. A limitation of the current technique in wall thickness measurements is that the transverse MR plane of section is not perpendicular to the long axis of the left ventricle. Consequently, such oblique sections through the left ventricle may give inaccurate absolute wall thickness measurements but can provide reliable estimate of regional wall thickening dynamics. The ability to define left ventricular wall thickness and function without contrast media provides a noninvasive technique for the detection of segmental left ventricular myocardial dysfunction in ischemic heart disease.

Adult↗
PubMed1985

Magnetic resonance imaging of developmental venous anomalies.

Magnetic resonance images (MRI) of nine subjects with a variety of developmental venous anomalies were studied retrospectively to assess the utility of MRI for determining the presence and type of venous abnormalities. Electrocardiogram-gated or nongated MR images were obtained in the transaxial, sagittal, and coronal planes. Venous anomalies detected with MRI were persistent left superior vena cava (three cases), total anomalous venous return (one), left inferior vena cava to left atrium (one), interrupted inferior vena cava with azygos (one) or hemiazygos (one) continuation, and retroaortic left renal vein (two). Congenital cardiac anomalies seen in conjunction with these defects were corrected transposition, coarctation of the thoracic aorta, complete transposition, and polysplenia with thoracic situs solitus and abdominal situs inversus. MRI clearly depicts developmental venous anomalies and associated congenital heart disease without the administration of contrast media, thus suggesting the potential of MRI as a noninvasive method for evaluating venous anomalies. Further experience is necessary to define the sensitivity and specificity of MRI in this regard.

Adolescent↗
PubMed1985

Pathologic blood flow in pulmonary vascular disease as shown by gated magnetic resonance imaging.

Axial, dual spin-echo magnetic resonance (MR) images, taken at the level of the pulmonary arteries and gated to the cardiac cycle, were qualitatively and quantitatively evaluated in nine patients with primary pulmonary arterial hypertension and six controls. In controls and patients, intravascular signal intensity was higher during diastole than during systole when fast flow conditions exist in the arteries; however, patients with severe pulmonary arterial hypertension showed significantly higher signals in the pulmonary arteries than did controls. A correlation between pulmonary vascular resistance and the MR signal in the right pulmonary artery in early systole (r = 0.89) showed the ability of MR images to provide information on blood flow and suggests a role for magnetic resonance in assessing the severity of this disease noninvasively. Flow-related cardiosynchronous variations in the lung parenchyma of controls were also observed; with further development, magnetic resonance may become useful to measure tissue perfusion and provide both pathoanatomic and pathophysiologic information. Furthermore, there was a significant difference between the MR signal intensity of dorsal and ventral lung regions.

Adolescent↗
PubMed1984

Periportal sinusoidal dilatation associated with pregnancy.

Periportal sinusoidal dilatation is an hepatic vascular lesion previously reported solely as a complication of oral contraceptive therapy. We report a case occurring during pregnancy and describe the angiographic appearance and pathologic findings. Peliosis hepatis is the main consideration in the differential diagnosis--the features distinguishing of these hepatic lesions are presented.

Adult↗