Magnetic resonance cholangiopancreatography documents bile leak site after cholecystectomy in patients with aberrant right hepatic duct where ERCP fails.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
A Aisen
Publications and source records attributed to A Aisen.
World Wide Web interface to digital imaging and communication in medicine-capable image servers.
As a trial project, the Indiana University Department of Radiology has develop[ed a low-cost manner of distributing radiological images throughout a medical environment using the World Wide Web (WWW). The interface requires the user to have a WWW-browser client, such as Netscape, running on UNIX, PC, or Macintosh platforms. A forms-based interface allows the user to query several DICOM-capable machines at the machine, patient, study, series, and image levels. Once an image transfer is initiated, images are prewindowed from 16- to 8-bits, compressed using public domain Joint Photographic Expert Group (JPEG) compression routines, transferred to the WWW client program, and decompressed and displayed using a locally selected image viewing program. At the currently implemented level of compression (75% quality), the entire fetch-transform-JPEG-display process takes 2 to 5 seconds over Ethernet, depending on the platform used.
Computer Communication Networks↗
Pancreatic adenocarcinoma: CT versus MR imaging in the evaluation of resectability--report of the Radiology Diagnostic Oncology Group.
PURPOSE: To compare findings with computed tomography (CT) and magnetic resonance (MR) imaging in pancreatic adenocarcinoma and to determine optimal pulse sequences for MR imaging. MATERIALS AND METHODS: CT scans and MR images were compared of 189 adult patients with known or suspected adenocarcinoma of the pancreas. Levels of confidence were correlated with surgical and pathologic results. RESULTS: The accuracy of CT was 0.73 and of MR imaging was 0.70. The negative predictive value of CT was 0.28 and of MR imaging was 0.23. The positive predictive value of CT was 0.89 and of MR imaging was 0.88. Gradient-echo and T1-weighted spin-echo sequences ranked equally in evaluation of vascular invasion, T1-weighted spin-echo sequences were preferred for assessing lymphadenopathy, and T2-weighted spin-echo sequences were preferred for detecting hepatic metastases. CONCLUSIONS: Cross-sectional imaging modalities are useful in the identification of unresectable pancreatic carcinoma. CT is recommended for initial imaging assessment.
Adenocarcinoma↗
Treatment of Wilson's disease with ammonium tetrathiomolybdate. I. Initial therapy in 17 neurologically affected patients.
OBJECTIVE: To test the efficacy and toxicity of a new drug, ammonium tetrathiomolybdate, in the initial treatment of a relatively large series of patients presenting with neurologic signs and symptoms caused by Wilson's disease. The key aspect of efficacy was to preserve the neurologic function present at the onset of therapy. DESIGN: An open study of 17 patients treated for 8 weeks each. Neurologic function was evaluated by frequent quantitative neurologic and speech examinations. Several copper-related variables were studied to evaluate the effect of the drug on copper, and a large number of biochemical and clinical variables were studied to evaluate potential toxicity. Patients were then followed up at yearly intervals, with follow-up periods of 1 to 5 years reported. SETTING: A university hospital referral setting INTERVENTION: Patients were generally treated for 8 weeks with tetrathiomolybdate, followed by zinc maintenance therapy. MAIN OUTCOME MEASURES: Neurologic function was evaluated by quantitative neurologic and speech examinations. RESULTS: None of the patients suffered a loss of neurologic function. Copper status and potential further toxic effects were generally well controlled quickly. No toxic effects resulted from administration of tetrathiomolybdate. During the ensuing period of follow-up of 1 to 5 years, neurologic recovery in most patients was good to excellent. CONCLUSIONS: Tetrathiomolybdate appears to be an excellent form of initial treatment in patients with Wilson's disease presenting with neurologic signs and symptoms. In contrast to penicillamine therapy, initial treatment with tetrathiomolybdate does not result in further, often irreversible neurologic deterioration.
Adolescent↗
Design of MRI scan protocols for use in 3-D, CT-based treatment planning.
MRI has the potential of providing the radiation therapy treatment planner with new insights into the definition of target and normal tissue volumes to augment CT in 3-D treatment planning. The current speed of MR scan sequences is not sufficient to enable the acquisition of both T1 and T2 weighted images in all three orthogonal planes in a reasonable period of time. Therefore, compromises must be made in the design of protocols specifically for use in radiotherapy planning which: (1) provide enough information to readily enable image registration; (2) preserve the three-dimensionality provided by image acquisition directly in coronal and sagittal planes; (3) yield tissue contrast as well as tumor specificity (where available); but (4) can be completed in a short enough span of time (or with enough checks) that the patient position is not compromised. Protocols designed for use in planning treatment of the brain, head and neck, lung, prostate, cervix, and sarcomas are presented.
Humans↗
Identification of brain lesions in neuropsychiatric systemic lupus erythematosus by magnetic resonance scanning.
Cranial magnetic resonance imaging in 28 systemic lupus erythematosus patients who had experienced 30 acute neuropsychiatric events showed focal brain lesions in 16 of 30 events (53%) and low brain volume (atrophy) in 20 of 30 events (67%). Definite focal lesions were significantly more frequent in patients with clinically localized neurologic deficits (8 of 8, 100%), or seizures (5 of 6, 83%) than in patients without such localizing signs (3 of 16, 19%). Many of these lesions were occult on intravenous contrast-enhanced x-ray computed tomography. In 2 patients, lesions in gray matter resolved within 2 or 3 weeks, in association with clinical improvement. Magnetic resonance imaging is an important technique for detecting the extent of brain injury in cerebral lupus.
Adult↗
Integration of magnetic resonance imaging into radiation therapy treatment planning: I. Technical considerations.
This paper presents the results of a feasibility study specifically addressing the technical and operational difficulties in making quantitative use of Magnetic Resonance Imaging (MRI) in radiation therapy treatment planning (RTTP). Selected radiotherapy patients have been studied with both CT and MRI as part of the treatment planning process. Both sets of images, along with mechanically-obtained external contour and simulator film data, are entered into the treatment planning system. All of the capabilities of the fully three dimensional planning system U-MPlan are available to both the CT and MRI images, in which any image can be used as the backdrop for interactive beam positioning, beam portal simulation, and dose distribution displays for external beam and brachytherapy applications in both 2- and 3-dimensionally-oriented displays. The study has shown that to use MRI data for RTTP, one must (a) use careful patient positioning and marking, (b) transfer information from CT to MRI and vice versa, (c) determine the geometrical consistency between the CT and MR data sets, (d) investigate the unwarping of distorted MR images, and (e) have the ability to use non-axial images for determination of beam treatment technique, dose calculations, and plan evaluation.
Brain Neoplasms↗
Assessment of portosystemic shunt patency and function with magnetic resonance imaging.
Magnetic resonance imaging (MRI) was performed in seven patients before and after portosystemic shunting to evaluate venous changes accompanying nonselective and selective shunt construction. The size and number of the intrahepatic portal and hepatic veins, left perirenal veins, and left upper quadrant varices were evaluated at MRI before and after shunt construction. MRI correctly diagnosed patent shunts in all seven patients. A marked decrease in the size of intrahepatic veins after a total or nonselective shunt suggests adequate portal vein and variceal decompression. Dilatation of left perirenal veins in the presence of a patent mesorenal or splenorenal shunt suggests hypertension of the left renal vein and possibly inadequate decompression of esophageal varices.
Adult↗
Sickle-cell nephropathy: MR imaging.
To study the nephropathy associated with sickle-cell disease (SCD), spin-echo magnetic resonance (MR) imaging of the kidneys was performed in 19 SCD patients, six with beta-thalassemia major (BTM), and ten healthy individuals as controls. Eleven SCD patients had decreased relative cortical signal, most evident on T2-weighted images. No correlation with serum ferritin, urine-concentrating ability, serum blood urea nitrogen, or creatinine levels was established. Iron deposition in the renal cortices of sickle-cell nephropathy patients may, at least in part, be responsible for the relatively diminished cortical signal intensity. No BTM patients, all of whom were clinically and biochemically in iron overload from frequent transfusions, demonstrated diminished renal cortical signal intensity. This suggests that renal changes in SCD seen on MR images are not due simply to systemic iron overload per se but perhaps reflect abnormalities of iron metabolism in the renal cortex peculiar to SCD nephropathy.
Adolescent↗
Left ventricular wall motion: its dynamic transmural characteristics.
Cardiac wall motion has been studied extensively. It is usually determined by indirect two-dimensional measurements for the true three-dimensional (3D) motion with its specific speed and direction. Errors are also introduced by using internally fixed reference systems and by the inability to identify precise points on the heart wall during the cardiac cycle. Because of these limitations, the endocardial and epicardial wall motion and their relationship are still unclear. This study was designed to assess endocardial and epicardial wall motion by measuring the direction and speed of implanted markers in an externally fixed 3D coordinate system. Fifty-seven pairs of endocardial and epicardial metallic markers were placed at anterior, lateral, posterior, basal, and apical regions of the left ventricles of 14 normal mongrel dogs. Biplane cineradiographs were performed at 50 frames/sec, and the 3D motions of the markers were analyzed using a specially designed computer system. It was found that the speeds, directions, displacements, and phases of the movements of corresponding endocardial and epicardial points were highly correlated. The correlation coefficients were 0.77 to 0.95 for the mean directions, 0.61 to 0.96 for the mean speeds, and 0.59 to 0.96 for the mean displacements at various regions of the heart, and the periodic movements of the endocardium and epicardium were always in phase. The mean epicardial speeds and displacements are fixed proportions (approximately 70%) of the mean endocardial speeds and displacements despite the differences in absolute values between regions in the same dog and the same regions in different dogs. The correlation coefficients for endocardial and epicardial instantaneous speeds, directions, and velocities ranged from 0.68 to 0.83, 0.81 to 0.88, and 0.77 to 0.86, respectively, for different regions of the heart. The correlation coefficients were significant for both the mean values and the instantaneous values. Thus, when only fixed epicardial points are accessible for wall motion measurements in clinical situations, it is possible to infer the endocardial motion from the epicardial motion.
Animals↗
Ultrasound examination of the colon.
Explore the source record for details and available documents.
Colon↗
Phantom for calibration of preoperative imaging modalities in endoluminal stent-graft repair of aortic aneurysms.
PURPOSE: Successful deployment of an endoluminal prosthesis for repair of an abdominal aortic aneurysm (AAA) is critically dependent on accurate preoperative assessment of aneurysm morphology with use of such modalities as contrast aortography (CA), spiral computed tomography (CT), magnetic resonance (MR) imaging, and intravascular ultrasonography (IVUWS). The authors describe a new phantom that could be used both to calibrate these four imaging modalities and to determine which imaging technique(s) is (are) best for preoperative AAA sizing. MATERIALS AND METHODS: A life-sized AAA model was constructed of silicone elastomers with luminal access ports for introduction of contrast media and catheters. Contrast material-filled rings were positioned circumferentially along the length of the model as reference points for dimension measurements. The modalities were compared to each other relative to the actual dimensions of the model, as determined at its construction. RESULTS: In this pilot study, all modalities were relatively similar in their ability to measure the dimensions of the AAA model. Length measurements accounted for most of the interinstitutional and interobserver variability. MR imaging had the least variability. CONCLUSIONS: The authors developed a new phantom that can be imaged successfully with CA, CT, MR imaging, and IVUS in repetitive, reproducible fashion. Structural refinements and future larger scale, statistically significant evaluations of such models should establish this as a useful adjunct in multicenter endoluminal stent-graft trials to allow calibration of imaging modalities and to determine which modality or modalities is (are) best for preoperative AAA sizing.
Aortic Aneurysm, Abdominal↗