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Biomedical subjects

J M Taveras

Publications and source records attributed to J M Taveras.

At least 19 recordsLinked to original sources
PubMed1991

Past, present, and future of radiology of meningioma.

The evolution of the radiologic findings associated with meningiomas represents a microcosm of the evolution of diagnostic radiology that has occurred since the discovery by Röntgen of the x-ray beam in 1895 and the founding of the Radiological Society of North America in 1915. What will the next new, as yet unimagined, imaging modality contribute to our current ability to detect and diagnose these lesions? No one can forecast this, but it should prove to be both fascinating and challenging.

Brain Neoplasms↗
PubMed1991

Abnormal corpus callosum: a sensitive and specific indicator of multiple sclerosis.

The authors investigated whether identification of corpus callosal (CC) involvement might increase the specificity of magnetic resonance (MR) imaging in differentiating multiple sclerosis (MS) from other periventricular white matter diseases (PWDs). They prospectively evaluated 42 patients with MS and 127 control patients with other PWDs. Ninety-three percent of the MS patients demonstrated confluent and/or focal lesions involving the callosal-septal interface (CSI). These lesions characteristically involved the inferior aspect of the callosum and radiated from the ventricular surface into the overlying callosum. CSI lesions were optimally demonstrated on sagittal long repetition time (TR)/short echo time (TE) images and frequently (45% of cases) went undetected on axial images. Only 2.4% of the control patients had lesions of the CC. The authors conclude that midsagittal long TR/short TE images are highly sensitive and specific for MS and that callosal involvement in MS is more common than previously reported.

Adult↗
PubMed1989

Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging.

The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio.

Adult↗
PubMed1986

Assessment of ventricular shunt patency by sonography: a new noninvasive test.

This report describes a new test of patency of the ventricular component of a ventriculoperitoneal shunt that precludes injection into the shunt reservoir. Preliminary clinical experience confirms that digital compression of the ventricular shunt reservoir (Cordis standard and pediatric reservoir), while occluding the shunt distal to the reservoir, generates microbubbles that increase the echogenicity of the catheter, demonstrating shunt patency. In vitro, the extrusion of microbubbles from catheter side holes can be imaged during digital compression of the reservoir, but so far this has not been imaged in patients as a direct sign of shunt patency. A sonographic means of assessing shunt function offers the advantage of simultaneously imaging the ventricular catheter, determining its location, and assessing the etiology of shunt failure. Its usefulness is limited to pediatric cases in which an adequate transfontanelle cranial sonographic study can be obtained and to individuals with large craniotomy defects.

Adolescent↗
PubMed1979

Computed tomography of masses in the lacrimal gland region.

Twenty patients with mass lesions in the lacrimal gland region were evaluated with computed tomography (CT). The extent of the mass and its relationship to the globe, optic nerve, and extraocular muscles were clearly seen. The CT appearance on plain scan and the presence or absence of contrast enhancement, bone involvement, and cystic components often suggested the specific pathological diagnosis. Although orbital ultrasonography and CT were frequently complementary, ultrasonography was more definitive in inflammatory diseases, while CT demonstrated better extraorbital extension.

Adenocarcinoma↗
PubMed1979

Evaluation of mucoceles of the paranasal sinuses with computed tomography.

Eighteen patients with mucoceles of the paranasal sinuses were studied by plain radiography, pluridirectional tomography, and computed tomography (CT). Sixteen of the lesions had a homogeneous appearance on CT but demonstrated variable absorption characteristics, with acutely infected mucoceles showing rim enhancement. Plain radiography and pluridirectional tomography were usually sufficient for making a diagnosis and defining the extent of the lesion, but CT more accurately demonstrated orbital and intracranial extension. Both transverse and coronal CT are essential for adequate evaluation.

Adolescent↗
PubMed1978

Computed tomography of the orbit with special emphasis on coronal sections.

Computed tomography (CT) is an extremely valuable noninvasive method for evaluating orbital soft-tissue structures. The possibility of scanning in the coronal plane has added a new dimension to the study. Direct enlargement viewing of scans on the display console has disclosed minute anatomic and pathologic details.

Humans↗
PubMed1978

Computed tomography of the paranasal sinuses and face: part I. Normal anatomy.

With the ability to image both bone and soft tissue structures, computed tomography (CT) is capable of visualizing many normal anatomical structures of the paranasal sinuses and face not seen with other radiological techniques. The superficial and deep fat planes, all of the muscles of mastication, and many of the facial muscles are readily identified. The extraocular muscles, optic nerves, and globes are clearly seen. The purpose of this report is to review the normal anatomy of the paranasal sinuses and face imaged by CT in both the transverse and coronal planes.

Face↗
PubMed1978

Computed tomography of the paranasal sinuses and face: part II. Pathological anatomy.

Computed tomography (CT) has added an important new dimension to the radiological evaluation of diseases of the paranasal sinuses and face. Using transverse and coronal scans, accurate assessment of the character and extent of mass lesions in this region can be achieved. Erosion of thin bony lamine and involvement of soft tissue structures of the face can be seen. Most important, CT is capable of precisely defining the extension of lesions into the pterygopalatine fossa, orbit, and cranial cavity, information that is essential for therapeutic planning.

Adult↗
PubMed1978

Computed tomographic evaluation of traumatic spinal injuries.

A full radiological evaluation of patients who sustained traumatic injuries to the spine may be difficult to obtain due to the danger associated with manipulation. Computed tomography offers a new modality for simple and accurate evaluation; valuable information may be gained without the use of invasive methods.

Humans↗
PubMed1978

Computed tomography of herpes simplex encephalitis, with clinicopathological correlation.

The computed tomographic (CT), clinical, and pathologic findings in 9 patients with biopsy-proven herpes simplex encephalitis (HSE) were reviewed. Seventeen scans (5 plain, 12 contrast enhanced) were analyzed. The major CT finding was a low-absorption abnormality, present in 11 of 17 scans (64%), affecting primarily the temporal lobes. Mass effect was evident in 9 of 17 (52%). Of the 12 contrast-enhanced scans, 6 (50%) showed an abnormal enhancement pattern affecting primarily the sylvian fissure and opercular areas. CT abnormalities are characteristic enough that, in the proper clinical setting, they lend support to the correct diagnosis.

Adolescent↗
PubMed1978

A model for regional cerebral oxygen distribution during continuous inhalation of 15O2, C15O, and C15O2.

Equilibrium positron brain scans were obtained during continuous inhalation of C15O, C15O2, and 15O2. Inhalation of C15O labels hemoglobin, whereas C15O2 instantaneously labels stable water to H215O. During the continuous inhalation of 15O2, body tissues extract it from the blood in proportion to local metabolism and ultimately convert it to water of metabolism. After 6-8 min of inhalation, a steady-state equilibrium is established in which the inflow of tracer is balanced by its disappearance due to radioactive decay (T1/2 = 2 min) and biologic removal. Mathematical models of the steady-state distributions of C15O, C15O2/H215O, and 15O/H215O are derived. The major results are: a) The steady-state distribution of C15O is insensitive to variations in blood flow and essentially measures blood volume. b) The distribution of H215O during inhalation of C15O2 is dependent, though nonlinearly, on blood flow. c) The distribution of H215O during inhalation of 15O2 depends linearly on the oxygen extraction fraction and nonlinearly on blood flow. d) The dependence on blood flow in the 15O2 steady-state image can be removed by the division, point by point, of the 15O2 image by the C15O2 image.

Brain↗