Biomedical subjects

F Jolesz

Publications and source records attributed to F Jolesz.

42 records · Page 3Linked to original sources

PubMedDate not supplied

Thoracic spinal metastasis from unexpected cerebellar medulloblastoma: the value of MRI.

A 28-year-old male was found on CT metrizamide myelography to have an intradural extramedullary tumor at the T8-T9 level. This was seen to compress the spinal cord, and on surgery it was proven to be medulloblastoma. Cranial CT scans disclosed only mild hydrocephalus and minimal anterior displacement of the inferior fourth ventricle on the right. However, magnetic resonance imaging (MRI) which was performed after the spinal surgery demonstrated an inferior cerebellar vermian tumor.

Adult↗

PubMedDate not supplied

MR diagnosis of dural venous sinus thrombosis complicating L-asparaginase therapy.

Dural venous sinus thrombosis is an important complication of L-asparaginase chemotherapy. The diagnosis and followup of this condition, using spin echo and fast imaging techniques, is described in three patients. Magnetic Resonance (MR) imaging is a rapid, noninvasive technique for diagnosis and follow-up of this condition. Fast imaging techniques can improve the assessment of these patients.

Adult↗

PubMedDate not supplied

Three-dimensional segmentation of MR images of the head using probability and connectivity.

We describe a three-dimensional (3D) segmentation method that comprises (a) user interactive identification of tissue classes; (b) calculation of a probability distribution for each tissue; (c) creation of a feature map of the most probable tissues; (d) 3D segmentation of the magnetic resonance (MR) data; (e) smoothing of the segmented data; (f) extraction of surfaces of interest with connectivity; (g) generation of surfaces; and (h) rendering of multiple surfaces to plan surgery. Patients with normal head anatomy and with abnormalities such as multiple sclerosis lesions and brain tumors were scanned with a 1.5 T MR system using a two echo contiguous (interleaved), multislice pulse sequence that provides both proton density and T2-weighted contrast. After the user identified the tissues, the 3D data were automatically segmented into background, facial tissue, brain matter, CSF, and lesions. Surfaces of the face, brain, lateral ventricles, tumors, and multiple sclerosis lesions are displayed using color coding and gradient shading. Color improves the visualization of segmented tissues, while gradient shading enhances the perception of depth. Manipulation of the 3D model on a workstation aids surgical planning. Sulci and gyri stand out, thus aiding functional mapping of the brain surface.

Algorithms↗

PubMedDate not supplied

Fast spin-echo imaging of intracranial neoplasms.

Our goal was to compare dual echo fast SE (FSE) T2-weighted MRI of intracranial neoplasms with conventional SE (CSE) images. In phase 1 of the study, CSE and FSE dual echo MR studies of 33 patients with intracranial neoplasms and 26 normal controls were separately interpreted by three neuroradiologists blinded to clinical history to ascertain differences in lesion conspicuity. The CSE and FSE images were read independently, in random order, with at least a 3 week interval between readings. In phase 2 of the study, CSE and FSE sequences were compared side by side by three neuroradiologists independently to evaluate lesion conspicuity and artifacts and to determine whether FSE would be an acceptable replacement for CSE imaging. Lesion detection was equivalent in 111 of 117 interpretations (94.9%). The CSE and FSE sequences were equivalent in detecting lesion-associated abnormalities (hemorrhage, calcium, mass effect, edema, and hydrocephalus) and in characterizing lesion size, margins, and signal intensity. Nonspecific T2 white matter hyperintensities were detected more often with CSE, while susceptibility artifacts were less conspicuous on FSE. Ventricular catheters, postoperative soft tissue and bony changes, and postradiation therapy changes were detected equally well on both sequences. In phase 2 of the study, lesion conspicuity and presence of artifacts were felt to be equivalent with the two sequences. The FSE sequences can serve as a rapid, feasible alternative to conventional CSE sequences for intracranial tumor detection.

Adolescent↗

PubMedDate not supplied

Neuroimaging and the lesion of multiple sclerosis.

In a patient with long-standing multiple sclerosis (MS), a double-dose delayed contrast-enhanced CT scan obtained during exacerbation revealed many areas of enhancement. Vigorous treatment with corticotropic hormone was followed by almost complete disappearance of these abnormalities. No areas of low attenuation were seen on a later unenhanced CT scan. Finally, MR imaging showed only a single area compatible with a plaque of MS. It is suggested that pathologic alteration of the blood-brain barrier seen in MS is not necessarily followed by demyelination and plaque formation. Restoration of the integrity of the blood-brain barrier may thus possibly prevent the formation of plaques in some MS patients, in particular if this can be accomplished early in the course of the exacerbation.

Adult↗

PubMedDate not supplied

Fast spin-echo MR imaging of the cervical spine: influence of echo train length and echo spacing on image contrast and quality.

PURPOSE: To examine the interaction of echo train length and interecho spacing and their effects on image quality and contrast in fast spin-echo sequences of the cervical spine. METHODS: Forty-three patients with suspected cervical disk disease were prospectively evaluated with fast spin-echo with varying echo train lengths and interecho spacing. A flow phantom was used to confirm findings related to cerebrospinal fluid pulsation. Parameters were manipulated to adjust contrast, signal-to-noise ratio, the effects of artifacts, and the speed of acquisition. RESULTS: In general, increasing echo train length increased homogeneity and high intensity of cerebrospinal fluid signal and reduced acquisition time; however, it decreased the signal-to-noise ratio of cerebrospinal fluid and cord and increased blurring, and, to a lesser extent, edge enhancement, and "truncation-type" artifact. Increasing interecho space permitted the use of longer echo times but minimally decreased contrast and signal-to-noise ratio of cord and cerebrospinal fluid. In addition, increasing echo spacing increased blurring, edge enhancement, truncation-type, magnetic susceptibility, and motion artifacts. CONCLUSIONS: For cervical spine imaging, a long echo train length and short echo spacing partially compensate for cerebrospinal fluid flow and produce the best myelographic effect but must be modulated by other constraints, such as artifact production or technical capabilities.

Cervical Vertebrae↗