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Biomedical subjects

P Pedrosa

Publications and source records attributed to P Pedrosa.

15 recordsLinked to original sources
PubMed1991

[Interpretation of MR tomography findings in trauma surgery].

MR-Imaging is well established as the most sensitive method for the diagnosis of avascular necrosis of the femoral head. In this paper preliminary results are analyzed in an attempt to clarify whether as in a vascular necrosis of the femoral head. MR changes after trauma or surgery allow conclusions concerning the vitality of the bone. Comparison of clinical, MR and histological findings revealed that we cannot yet differentiate between fibrosis of the bone marrow with sustained vitality of the osteocytes and bone necrosis. Therefore, conclusions with implications for therapy should be drawn with extreme care.

Adult↗
PubMed1990

[A simple method for MRI-assisted radiotherapy planning in brain tumors].

A simple method for radiation therapy planning of brain tumors is presented. Therapy portals of midline tumors can easily be determined by comparing sagittal MRI scans with the lateral simulator radiograph. By addition of appropriately processed MR-tomograms a similar planning is possible for parasagittal tumors. Digital data exchange between different operating systems is not necessary with our simple method, problems with varying input/output standards and expensive hardware requirements are thus avoided.

Adult↗
PubMed1989

MR imaging of cerebral tumors: state of the art and work in progress.

MR imaging of the brain has made tremendous progress during the last years. This technique is generally superior to computed tomography (CT) in brain tumors, due to its capability for direct imagining in various planes and its high tissue contrast. Moreover, the detectability and differentiation of extraaxial tumors, previously the domain of CT, has been improved with paramagnetic contrast agents (PCA). Although, the sensitivity of MRI for intracranial tumors is unchallenged, the specificity for such tumors is not remarcably greater than that of CT. Differentiation between high grade glioma, abscess and metastasis still requires biopsy for definitive diagnosis. Methods for improvement of specificity--tissue characterization--are currently being evaluated in a clinical setting. Further development in this field is necessary before such methods can be applied on a routine basis.

Brain Neoplasms↗
PubMed1989

[MR tomography of astrocytic tumors (I-III)].

Magnetic resonance (MR) imaging was performed on 37 patients with histologically confirmed astrocytomas (I-III). In addition, the MR tissue parameters T1, T2 and proton density (RHO) were analysed by an interlaced CPMG spin echo sequence. Characteristic morphologic tumour patterns which subdivide astrocytomas into each different tumour grade are presented. Quantitative analysis of MR tissue parameters provides a statistically proven classification of each tumour grade and allows differentiation between "semibenign" astrocytomas (II) and "relatively malignant" astrocytomas (III), with high accuracy.

Adolescent↗
PubMed1989

[Transient osteoporosis or femur head necrosis? Early diagnosis using MRT].

Transient osteoporosis of the hip is a syndrome that does not seem to be widely known; this is also true for its radiological appearance. It is often mistaken for avascular necrosis of the femoral head, metastatic or inflammatory disease. These differential diagnoses lead to more or less invasive procedures, although transient osteoporosis does not require more than immobilisation for complete remission. MRI was done in 38 patients with acute hip pain, 13 had femoral head necrosis and 8 transient osteoporosis. Follow-up studies via MRI in patients with transient osteoporosis revealed 3 stages (diffuse, focal, residual) during the clinical course of which stage II is similar to femoral head necrosis but always without the typical sclerotic rim.

Adolescent↗
PubMed1989

[Magnetic resonance tomography using gadolinium-DTPA in the diskectomy syndrome--a reliable method of identifying a recurrent prolapse in scar tissue].

The non invasive diagnostic possibilities of MR have resulted in better diagnosis of degenerative spinal diseases. Twenty-one patients with failed back surgery syndrome (postdiscectomy syndrome) were studied to evaluate the possibility of 1-Tesla magnetic resonance (MR) imaging with gadolinium diethylene triamine pentaacetic acid (Gd-DTPA) in differentiating post operative scar tissue from recurrent disc herniation. The enhanced MR studies correctly depicted the character of abnormal epidural tissue in all patients. We conclude that MR with GD-DTPA might be the method of choice to differentiate reliably postoperative epidural fibrosis from recurrent disc prolapse.

Adult↗
PubMed1989

Bone grafting in total hip replacement. Preliminary results with MRI.

MRI of ten hip joints in nine patients with total hip replacement and reconstruction of the acetabulum with autologous bone grafts, were reviewed. The viability of inserted bone grafts was clearly documented by MRI. Characteristic differences in signal intensity between autologous and homologous bone grafts are discussed. Despite extended metallic artifacts in the operated region, sufficient diagnostic information was available in most cases. No side effects were reported.

Aged↗
PubMed1989

[Intracranial hemorrhage in MRT].

About 10% of all intracranial findings in cranial MRI were hemorrhages, or findings associated with bleeding. There was great variation in the hemorrhages as a result of their location and their age, and this could disguise the underlying lesions. Therefore a knowledge of the typical appearance of spontaneous bleeding and tumor bleeding is necessary for interpretation of the MRI findings. During its course, cerebral bleeding shows all of the known interactions between biochemical and histological factors and MRI signal. Thus, an understanding of the variations during the clinical course of bleeding is helpful for a better understanding of contrast mechanisms in MRI.

Cerebral Hemorrhage↗
PubMed1988

[MR tomography in tumors of the posterior cranial fossa in childhood].

MR tomography was performed on 23 children with tumors in the posterior fossa. In 14 cases, the MR tissue parameters were determined. Astrocytomas can be easily differentiated from medulloblastomas and ependymomas on the basis of their localization and signal intensities. Grading of astrocytomas and distinction between medulloblastomas and ependymomas was not possible. Because of high tissue contrast, multiplanar imaging and minimal artifacts, MR proved to be the method of choice for planning surgery and for the follow-up of tumours in the posterior fossa.

Adolescent↗
PubMed1988

[MR tomography of thoracic and abdominal tumors in childhood and adolescence].

MRI was performed on 25 infants, children and adolescents with thoracic and abdominal tumours. The specific contribution of MRI to diagnosis, treatment planning and therapy monitoring is demonstrated. In some cases the T1 and T2 relaxation times were determined; this may clarify the different signal intensities of tumour and neighbouring organs and contribute to differentiation between Wilm's tumour and neuroblastoma.

Abdominal Neoplasms↗
PubMed1988

[Gadolinium dimeglumine gadopentetate compared to CPMG sequencing and image synthesis].

The skulls of 46 patients were examined by means of ordinary scans and after contrast. 24 of these patients with cerebral abnormalities had scans, using identical planes, with and without contrast and with CPMG sequences. Contrast in intracranial, but extracerebral (extra-axial), tumours (meningiomas, neurinomas) was much better after using contrast, but intracerebral (intra-axial) tumours were mostly shown as well on T2-rated CPMG sequences. Image synthesis has shown that contrast uptake occurred only in solid tumour regions.

Brain Diseases↗
PubMed1988

[Results of nuclear magnetic resonance tomography studies in endocrine orbitopathy].

Magnetic resonance imaging (T1- and T2-weighted) was performed in 65 patients with Graves' disease. In addition, T2 relaxation times of each ocular muscle were measured. Of the muscles thus studied, 54.8% showed a thickening in coronary tomograms. An interaction between the optic nerve and the thickened ocular muscles at the apex of the orbit was suspected in 30.1%. It could not be confirmed that the thickening of the muscles and the T2 value were related. However, there was a high correlation between the rise in intraocular pressure and the T2 relaxation time. These results imply that the T2 relaxation time is extremely useful in interpreting the activity of Graves' disease and provide a diagnostic tool of prognostic value in monitoring and treating this disease.

Adolescent↗