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Biomedical subjects

L Prayer

Publications and source records attributed to L Prayer.

At least 19 recordsLinked to original sources
PubMed2006

[Indications for fetal magnetic resonance imaging].

Indications to perform fetal magnetic resonance imaging (MRI) are composed of common ones related to methodological problems of ultrasound (US) assessment (such as for instance hydramnios) and special ones. The latter are related to MR capability of high-resolution soft tissue contrast and an extended field of view that allows visualization of the whole fetus, even in later stages of pregnancy. The most important indications include confirmation of US findings, work-up of malformations with respect to individual prognosis and genetic background, differentiation between acquired conditions and malformations, visualization of pathologies that have to be treated surgically immediately after birth, and morphological changes of the placenta.

Congenital Abnormalities↗
PubMed1997

Diffusion-weighted MRI of myelination in the rat brain following treatment with gonadal hormones.

Previous studies have demonstrated the ability of high-resolution diffusion-weighted MRI to show maturation of white-matter structures in the developing rat brain. The purpose of this study was to investigate the influence of gonadal steroid hormones on the rate of this development. Starting from their second postnatal day, 16 rat-pups of either sex were repeatedly treated with subcutaneous implants containing 17-beta estradiol or delta-androstene 3,17 dione, respectively. Serial T1-, T2- and diffusion-weighted MRI was performed weekly for 8 weeks using a 4.7 T unit. Maturation of anterior optic pathways and hemisphere commissures was assessed. Diffusion-weighted images were processed to produce "anisotropy index maps", previously shown to be sensitive to white-matter maturation. Compared with untreated rat-pups, estrogen-treated animals showed accelerated, and testosterone-treated animals delayed maturation on anisotropy index maps and histological sections. In all animals, maturational changes appeared earlier on anisotropy index maps than on other MRI sequences or on myelin-sensitive stained sections. Diffusion-weighted imaging, and the construction of spatial maps sensitive to diffusion anisotropy, seem to be the most sensitive approach for the detection of maturational white-matter changes, and thus may hold potential for early diagnosis of temporary delay or permanent disturbances of white-matter development.

Androstenediol↗
PubMed1994

The diagnostic value of magnetic resonance imaging for the detection of tumor recurrence in patients with carcinoma of the ovaries.

Disease status during follow-up evaluation of patients with carcinoma of the ovaries is the main criterion for the selection of appropriate management. A cohort analysis was performed to investigate if magnetic resonance imaging (MRI) could improve noninvasive assessment of disease status in patients with carcinoma of the ovaries during follow-up examination. Twenty-four women with carcinoma of the ovaries after primary surgical treatment with subsequent platinum containing chemotherapy were entered into the study. MRI was performed in addition to sonography and computed tomography (CT). Patients without evidence of disease underwent restaging laparotomy. Sensitivity of sonography, CT and MRI was 50, 63 and 75 percent, respectively. Combination of CT and MRI revealed a 75 percent sensitivity rate. Specificity for sonography, CT and MRI was 100, 94 and 94 percent, respectively, and for the combination of CT and MRI, 88 percent. Positive and negative predictive value and accuracy of these methods were 100, 80 and 83 percent for sonography; 83, 83 and 83 percent for CT; 86, 88 and 88 percent for MRI, and 75, 88 and 83 percent for the combination of CT and MRI. In one instance of false-negative sonographic and CT results, MRI detected recurrence located in postoperative scar tissue. In one instance, MRI did not add essential information to the other imaging methods. Therefore, MRI as a time- and cost-intensive procedure should be reserved for instances in which there are doubtful findings arising with other diagnostic tools, rather than as an indispensable routine procedure in the follow-up evaluation of patients with carcinoma of the ovaries.

Adult↗
PubMed1994

MR assessment of brain maturation: comparison of sequences.

PURPOSE: To evaluate the role of short-inversion-time inversion-recovery (STIR) sequences in assessment of brain maturation. METHODS: Twenty-seven infants and young children with normal neurologic development were examined by 1.5-T MR using a circularly polarized head coil. Axial T1-weighted and T2-weighted and spin-echo and STIR images were obtained. Signal intensity of different anatomic structures at individual sequences was classified relatively to reference sites and temporal sequence of signal intensity was observed. RESULTS: Signal intensity changes on T1-weighted and T2-weighted spin-echo sequences occurred at ages described in various previous publications. On STIR images intensity changes became apparent at a time between T1-weighted and T2-weighted images. The advantages of the STIR sequence were improved assessment of myelination of subcortical cerebral white matter from 6 to 14 months and good contrast between white matter lesions and cerebrospinal fluid. CONCLUSION: Our results suggest that from 0 to 6 months myelination can be assessed best using a combination of T1-weighted and T2-weighted images; from 6 to 14 months a combination of T2-weighted and STIR images seems to be advantageous; after 14 months the use of only T2-weighted sequences is sufficient. After 14 months STIR images may be useful in detecting small periventricular white matter lesions or in cases with retarded myelination and isointensity between gray matter and white matter.

Brain↗
PubMed1993

Haemorrhage in intracerebral arteriovenous malformations: detection with MRI and comparison with clinical history.

Fifty-one patients with 59 angiographically proven cerebral arteriovenous malformations (AVMs) were examined by high-field MRI to detect blood breakdown products. Results were correlated with the history of intracranial bleeding. Evidence of previous episodes of haemorrhage was seen in 10 of 12 patients (83.3%) with verified bleeding, in 4 of 9 patients (44.4%) with symptoms which could suggest bleeding and in 6 of 30 patients (20%) with negative histories. Because of the known rebleeding rate and the increased risk of associated complications, identification of the subgroup who had had haemorrhage and should therefore be considered for surgery may be beneficial. MRI can make a contribution to management by demonstrating prior haemorrhage in patients with an inadequate clinical history.

Adolescent↗
PubMed1993

Polymyositis: MRI-appearance at 1.5 T and correlation to clinical findings.

The thigh regions of 10 patients suffering from polymyositis were examined by magnetic resonance imaging (MRI) at 1.5 T; follow-up examinations were performed in all patients. MRI findings were correlated with findings at physical examination and serological parameters. In four patients focal areas of hyperintensity on T2-weighted (T2W) spin echo (SE) images were found within muscles. They were not detectable on T1-weighted (T1W) images. In three of these cases enhancement within the musculature was seen following i.v. administration of Gd-DTPA on T1W images. In another five patients there was varied replacement of muscle by fatty tissue. In one patient the muscle appeared completely normal. On follow-up three patients showed definite changes in imaging findings; two correlated well with clinical and biochemical findings while the third exhibited massive deterioration clinically with mild improvement on imaging. Seven patients exhibited no change on MRI; four of these had shown a significant clinical change in the course of the disease, whilst three were clinically stable. In our small series MRI using SE technique (T1W and T2W) and contrast enhancement to date seems to be of limited value for the assessment of muscular changes during therapy. The i.v. use of Gd-DTPA did not add to MRI's diagnostic value in this series.

Adult↗
PubMed1993

Wilson's disease: evidence of subgroups derived from clinical findings and brain lesions.

Using exploratory factor analysis, we prospectively investigated neuropsychiatric symptoms and structural brain lesions of 47 patients with proven Wilson's disease and identified three subgroups. The first subgroup clinically exhibited bradykinesia, rigidity, cognitive impairment, and an organic mood syndrome and by MRI showed a dilatation of the third ventricle. The second subgroup was characterized by ataxia, tremor, reduced functional capacity, and focal thalamic lesions. The third subgroup showed dyskinesia, dysarthria, an organic personality syndrome, and focal lesions in the putamen and in the pallidum.

Adolescent↗
PubMed1993

Superparamagnetic particles as oral contrast medium in magnetic resonance imaging of patients with treated ovarian cancer--comparison with plain MRI.

In 23 patients with treated ovarian cancer, 24 magnetic resonance (MR) examinations of the abdomen and pelvis were performed before and after administration of an oral superparamagnetic contrast medium. Depiction of bowel loops was judged sufficient in 47% with plain scans and in 85% with enhanced scans. Minor artefacts attributed to the agent were noted in 32% of examinations and were classified as disturbing in 8%. The diagnostic information obtained after contrast enhancement was estimated to be superior to that from plain MRI in 20% of patients. The use of oral contrast medium did not alter the MR diagnosis of "tumour recurrence" or "disease-free" in any patient. Our results suggest that superparamagnetic iron oxide is an effective and reliable approach to negative bowel contrast enhancement, increasing the confidence level when distinguishing intestines from solid structures.

Adult↗
PubMed1993

Posturographic measurement of body sway in survivors of severe closed head injury.

Postural imbalance was measured in 39 survivors of severe closed head injury 7 to 66 months after head injury using a posturographic platform. The results were compared with those derived from age-matched healthy control subjects. Severe postural imbalance, particularly in an anteroposterior direction, was found in 16 patients, whereas 9 patients showed moderate imbalance and 14 patients showed normal results in the posturographic investigation. Low initial Glasgow Coma Scale scores and deep parenchymal brain lesions demonstrated by magnetic resonance imaging were shown to be significant indicators of subsequent severe postural imbalance. The duration of posttraumatic amnesia, the localization and size of cortical contusions and subcortical white matter lesions, on the contrary, were not associated with postural imbalance in the long-term outcome.

Adolescent↗
PubMed1993

Cranial MR imaging and cerebral 99mTc HM-PAO-SPECT in patients with subacute or chronic severe closed head injury and normal CT examinations.

Eighteen patients in the subacute or chronic state following severe closed head injury with normal cranial CT scans were examined by MR and 99mTc HM-PAO SPECT. Correlations were sought between these 2 imaging modalities and the clinical outcome, as defined by the Glasgow Outcome Scale (GOS) score. Both MR and SPECT revealed cerebral damage in all patients examined but structural and functional alterations did not coincide topographically in 64.9% of lesions. Nevertheless, complementary injury patterns suggesting poor recovery were found; cortical contusions and diffuse axonal injury (MR) in conjunction with cortical and thalamic hypoperfusion (SPECT) were noticed in 8 out of 12 patients with unfavorable outcome (GOS = III and IV). The synthesis of MR and SPECT information clearly enhanced the ability both to accurately assess posttraumatic brain damage and to improve patients' outcome prediction.

Adolescent↗
PubMed1992

CT in pancreatic involvement of non-Hodgkin lymphoma.

In an attempt to evaluate characteristic CT features of primary pancreatic involvement in non-Hodgkin lymphoma (NHL), scans of 10 patients were reviewed retrospectively and compared to 50 patients with histologically proved different neoplasms of the pancreas. Setting the correct diagnosis of NHL would be essential for planning of treatment and prognosis. CT findings of NHL were characteristic but not specific. Nevertheless, the presence of a homogeneous pancreatic mass with a diameter of 7 cm or more, infiltrating surrounding tissue accompanied by retroperitoneal and/or mesenteric lymphadenopathy strongly suggests NHL. CT-guided needle biopsy can help to establish the diagnosis of pancreatic NHL.

Adult↗
PubMed1991

MRI in basal ganglia diseases.

76 patients suffering from different basal ganglia diseases (28 cases with M. Parkinson, secondary parkinsonism and Parkinson diseases; 5 cases with Chorea Huntington; 5 cases with Fahr disease and 38 cases with M. Wilson) MRI featured 2 characteristical patterns: 1. abnormal deposition of minerals, 2. focal atrophies of involved organs. Thus MRI provides with informations about: 1. differential diagnosis in clinically misleading courses, 2. stage and, as a consequence, prognosis of some diseases, 3. biochemical processes of diseases in vivo.

Adolescent↗
PubMed1991

[The percutaneous catheter drainage of pancreatic pseudocysts].

The results of CT/US-guided percutaneous drainage in 35 patients with pancreatic pseudocysts are reported. 27 patients recovered without surgery and no further treatment was required. 8 patients required a subsequent surgery due to recurrence. The role of CT/US-guided percutaneous drainage in pancreatic pseudocysts as well as an analysis of the technical aspects associated with a successful procedure are discussed. Although US may be used, we believe CT is safer and allows more precise localisation and guidance in the treatment of pseudocysts.

Adult↗
PubMed1991

Comparison of functional and structural brain disturbances in Wilson's disease.

We assessed the functional and structural brain disturbances in Wilson's disease (WD) by evoked potentials (EPs) and magnetic resonance imaging (MRI). All the 25 neurologically symptomatic and 44% of the 16 asymptomatic patients, assessed by both EPs (n = 48) and imaging (n = 41), had at least 1 abnormality of either prolonged EP conduction times, imaging-outlined presence of cerebral lesions, or brain atrophy. Our findings indicate that EPs and MRI are sensitive techniques for the evaluation of brain involvement in WD.

Adult↗
PubMed1991

[Diagnosis of cerebrovascular disorders using nuclear magnetic resonance tomography].

Regarding cerebrovascular diseases magnetic resonance imaging (MRI) provides informations which could not be obtained before by any other imaging method. MRI permits an early detection of ischemic infarctions, exact delineation of lesions near to skull base, and microangiopathy. Further diagnosis of arteriovenous malformations and venous thromboses can be done without using contrast media. Exclusion of acute hemorrhage or subarachnoidal hemorrhage is still a domain of computed tomography (CT). Other MR methods, like magnetic resonance angiography (MRA) and magnetic resonance spectroscopy (MRS) are expected to replace angiography and positron emission tomography (PET) in the near future, at least for some purposes.

Adult↗
PubMed1990

Evoked potentials in assessment and follow-up of patients with Wilson's disease.

Treatment of 9 patients with Wilson's disease was prospectively studied with evoked potentials and magnetic resonance imaging (MRI). Oral penicillamine therapy led to a decrease in auditory brainstem (ABP) and somatosensory (SEP) conduction times in 6 and 4 neurologically symptomatic patients, respectively. ABP and SEP were normal in 3 other symptom-free patients. MRI showed cerebral lesions in 4 of 7 patients. Quantified indices of brain atrophy were unaffected by treatment. ABP and SEP may reveal a reversible component of the disease that cannot be detected by MRI, and may be a more sensitive measure of treatment efficacy.

Administration, Oral↗