Biomedical subjects
Publications and source records attributed to A N Hasso.
T1 and T2 relaxation times of agar phantoms containing L-dopa melanin and Fe3+ were measured under MRI conditions. Fe3+ shortened T1 and T2 relaxation times. Melanin influenced relaxation times only in the presence of Fe3+; thus, contrast in MR images of the basal ganglia may depend upon levels of both paramagnetic iron and neuromelanin.
The kleeblattschädel deformity is a rare craniofacial condition typified by its trilobed, cloverleaf skull. The pathophysiology of this process is controversial. The morphologic, radiographic, and histologic abnormalities identified in the cranial base of an 18-gestational-week fetus with kleeblattschädel skull have not been described previously. Recently, the intrauterine diagnosis of kleeblattschädel was established by serial ultrasonography and, based on this evidence, the fetus was aborted. The fetus was studied extensively. Standard radiographs and high-resolution CT scans were obtained. Three-dimensional, reformatted contour surface images were constructed from the CT scan data. The cranial base was examined grossly, radiographically, and histologically. Histologic microanatomic study concentrated on structures of the mid-sagittal cranial base from the occiput to the mid maxilla. The distorted cranial architecture in kleeblattschädel deformity has, in the past, been attributed largely to the cranial base deformity which secondarily distorts the developing brain. Our study, however, suggests that the calvarium itself may be the primary focus of abnormal events leading to synostosis. The findings in this study seem to be inconsistent with earlier theories about the abnormal development of craniodysostoses.
Magnetic resonance imaging is the preferred cross-sectional imaging study for the evaluation of nearly all extra-axial brain tumors in adults. This article outlines the neoplasms by their pathology. The discussion covers the neoplasms originating from central neuroglial cells, meninges, and cranial nerves. In addition, developmental tumors and cysts and secondary extra-axial tumors are discussed.
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Choroid plexus papillomas are rare, constituting approximately 0.5% of all intracranial neoplasms. Four benign choroid plexus papillomas and one choroid plexus carcinoma were retrospectively reviewed in patients aged 4-20 months who had been examined with magnetic resonance (MR) imaging with a field strength of 0.5 T or 1.0 T and with computed tomography (CT) before and after the administration of contrast material. In general, the tumors were of intermediate signal intensity on T1-weighted images and of either intermediate or increased signal intensity (T2 lengthening) with T2 weighting. All demonstrated variable areas of internal signal void interpreted as signifying regional blood flow, calcification, or old hemorrhage. CT findings included relatively uniform contrast enhancement. Microscopic pathologic changes of the benign lesions mimicked the appearance of normal choroid plexus and confirmed the highly vascular nature of these tumors. MR imaging, with its high-resolution multiplanar techniques, offers direct visualization of these lesions in relation to normal anatomy and better discrimination and confirmation of their intraventricular location, facilitating surgery and postoperative follow-up.
To determine the clinical significance and specificity of suspected intratumoral hemorrhage in pituitary adenomas, we reviewed the clinical presentations, CT results, and findings at surgery in 12 patients who had hyperintense signal within intrasellar and suprasellar masses on short TR/TE spin-echo MR pulse sequences. Eight of the cases were confirmed at surgery. In seven of the operated cases, hemorrhage was found within pituitary adenomas and in the eight case there was hemorrhage but no identifiable adenomatous tissue. Nine of the 12 patients had CT scans; three had focal areas of increased attenuation, four had focal areas of decreased attenuation, and two had uniform hypoattenuation. All nine of these CT abnormalities correlated with areas of hemorrhage on MR. Three patients had clinical apoplexy; in two there was increased attenuation on CT and in one it was decreased. We found that intratumoral hemorrhage may be seen without clinical evidence of pituitary apoplexy, and that the areas of hemorrhage can appear as low attenuation on CT. CT may be better for visualizing intratumoral hemorrhage within the first few days, but MR is more sensitive in detecting and following the hemorrhage in the subacute stage.
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MRI is the procedure of choice for diagnosing most internal derangements. MRI provides images that not only demonstrate bony detail but show excellent representation of soft tissues in both anatomic and semifunctional relationships. MRI does not use ionizing radiation and has no known adverse effects. Multiplanar imaging allows a three-dimensional analysis of the TMJ, providing a more complete assessment of the condyle, articular disc, fossa relationships. Whenever capsular adhesions or disc perforations are suspected and are not demonstrated with MRI, then arthrography should be performed.
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Two patients with severe cerebral symptoms of toxemia of pregnancy were examined using computed tomography (CT) and angiography. CT disclosed extensive areas of low attenuation within the cerebral hemispheres. Angiography revealed constriction and narrowing of proximal and peripheral vessels suggesting vasculitis with extensive areas of impaired regional cerebral blood flow. A review of the known pathology and the theories regarding the pathophysiology of the cerebral effects of toxemia is presented.
The most common serious consequences of trauma to the temporal bone are hearing loss and facial nerve paralysis. In order to prevent these sequelae, radiologic evaluation is often necessary. CT offers specific information about the extent of injury, including the presence of bony fragments that need removal in order to free the facial nerve.
During the past 30 years, rapid and extensive progress has been made in diagnostic imaging of the petrous temporal bone, especially in the techniques of complex motion (pluridirectional) tomography, computed tomography, and magnetic resonance imaging. Because there are a variety of imaging techniques for evaluation of the petrous temporal bone, it is essential to utilize the optimal examinations. Economic factors and the need to reduce unnecessary radiation exposure for the patient are both important considerations.
A Siemens 0.5 Tesla Magnetic Resonance Imaging (MRI) system was used with the saddle head coil and transverse scout localization for imaging 10 normal cervical carotid artery bifurcations in the sagittal plane. Good to excellent visualization of the flow voids and vessel contours was accomplished in all cases. Careful technique and patient cooperation are required.
Retrospective analysis of axial CT scans from 600 consecutive pediatric patients revealed 37 patients (6%) with abnormal low density pericerebellar spaces. Fourteen of these 37 patients (38%) were diagnosed as cerebellar atrophy, whereas 23 of the 37 patients (62%) were diagnosed as mass-like pericerebellar fluid collections. Detailed analysis of the morphology of these spaces suggests that the CT criteria proposed in this paper distinguish between (a) those low attenuation pericerebellar spaces that represent cisternal dilatation caused by cerebellar atrophy (Group I - Atrophy) and (b) those low attenuation pericerebellar spaces that represent low density mass-like collections of fluid which distort a relatively normal cerebellum (Group II - Collections). Analysis of the medical records of the patients in Group II - Collections reveal a high incidence of prematurity, developmental delay, difficult birth and head trauma, possibly indicating that such collections represent sequelae of birth.
The computed tomograms of temporomandibular joints in 25 patients (41 joints) were retrospectively evaluated for condylar position and joint space with General Electric computer software. Computed tomography scans of the temporomandibular joint were made in the axial plane with the teeth in centric occlusion, and measurements were made from vertically reformatted images. Interarticular joint spaces were measured anterosuperiorly, superiorly, posterosuperiorly, and posteriorly from the condylar surfaces. This was repeated in five equidistant (3.1 mm) serial sagittal planes across the condyle, beginning and ending, on average, 2.5 mm from the lateral and medial condylar poles. Articular disk positions (anterolateral, anterior, anteromedial, medial, and normal) were correlated with condylar position. Significant differences between disk positions and joint spaces were found most frequently in the anterosuperior and the superior joint interval. When the disk was positioned normally, the anterosuperior joint space was consistent (1.5 to 2.0 mm) across the joint (standard deviation, 0.3 to 0.8 mm). The superior, the posterosuperior, and the posterior joint spaces in the normal joint were greater than the anterosuperior joint space. When the disk was anterior to the condyle, the anterosuperior joint interval was widened. When the disk was medial, the superior joint space was significantly wider than normal across the breadth of the condyle. In those joints in which the disk was anteromedial, there was an absence (0.2 mm) of joint space, and this occurred in all areas of the condyle except in its medial one fourth. In the internally deranged joint, joint space narrowing may be focal in nature.
The computed tomograms of 43 patients who had suffered craniofacial trauma and who were referred for evaluation of complaints of temporomandibular joint (TMJ) pain and dysfunction were reviewed. Fifteen of the 43 patients (34%) had sustained fractures, 16 (37%) had documented articular disc derangements without associated fractures, and 32 patients (74%) had degenerative joint changes. Computed tomography (CT) showed fractures, degenerative joint changes, and articular disc displacements not seen on conventional radiographs indicating that CT is particularly useful when patients' symptoms are not adequately explained by conventional radiographs or tomograms.
Seven patients with symptomatic fibromuscular dysplasia have had eight internal carotid arteries treated by operative balloon dilatation. This technique is described in detail and provides three distinct advantages over conventional graduated intraluminal dilatation--atraumatic passage of the catheter through the affected vessel with fluoroscopic guidance; precise dilatation of the involved segment of the internal carotid artery; and the application of a radial force against the arterial wall rather than a longitudinal shear force, thereby making intimal damage less likely. There were no treatment complications in this group of patients. This technique of balloon angioplasty is compared with the results of treatment in eight patients with fibromuscular dysplasia of the internal carotid artery, who had percutaneous transfemoral angioplasty. Long-term follow-up revealed the resolution of symptoms in all patients.