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Biomedical subjects

G Nilsen

Publications and source records attributed to G Nilsen.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cerebral magnetic resonance imaging (MRI) of very low birth weight infants at one year of corrected age.

Cerebral MRI was performed at 1.5 T in 27 infants with birth weight below 1500 grams at 1 year of corrected age. The images were compared to those reported on normal development at the same age. On T1 weighted images, 20 (74.1%) of the 27 infants showed myelin deposition different from what has been reported to be normal. Areas most affected were the central occipital white matter and the centrum semiovale. Both correspond to "watershed areas" known to be at risk for periventricular leukomalacia in preterm infants. T2-weighted images showed delayed myelination in the same areas as described for T1. In addition, two infants showed delayed myelination in the central occipital white matter and one in the centrum semiovale. Patchy focal abnormalities involving the white matter were seen in seven (25.9%) infants. Mild cerebral atrophy, mainly of the cortex was found in 10 (37.0%) infants. Irregular shape of the lateral ventricles, especially of the occipital horns was present in 12 infants (44.4%). 11 of these infants also had deviating changes in myelination. Only 2 infants (7.4%) had a normal MRI examination. Follow-up MRI examinations are needed to determine whether the high percentage of changes in myelination represent delayed development or brain damage in preterm infants.

Atrophy↗
PubMed1992

The use of MRI in the investigation of leg oedema.

Magnetic resonance imaging (MRI) was used in the diagnosis of various conditions giving rise to leg oedema, with special attention to the oedema after femoro-distal vascular reconstruction for obliterative atherosclerosis (n = 14). Patients with deep venous thrombosis (n = 6), chronic lymphoedema (n = 6) and closed muscular compartment syndrome (n = 2) were also investigated. Leg volume increase was measured according to the formula of a truncated cone. Interstitial fluid hydrostatic pressure (Pif) was recorded with the wick-in-needle technique. Spin echo series with 10 mm transverse slices were obtained with MRI. Following vascular reconstructions, leg volume increased 26% on the operated side. In the operated leg, no gradient in Pif was found between the posterior muscular compartment and the subcutaneous tissue. However, there was a significantly higher Pif in the subcutaneous tissue compared to the anterior muscular compartment (p less than 0.05). In the operated group, MRI revealed oedema around the entire circumference of the leg, mainly restricted to the subcutaneous tissue. In contrast, oedema of the leg muscles, particularly in the posterior compartments, was typical for patients having deep venous thrombosis. The group with chronic lymphoedema showed circumferential subcutaneous oedema alone or in combination with a fibrotic honeycomb pattern. Oedema of the affected muscular compartment was easily observed in patients who had a closed compartment syndrome. In conclusion, the use of MRI is promising in the investigation of conditions giving rise to leg oedema. It is likely that the formation of post-reconstructive oedema is taking place in the subcutaneous tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects.

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.

Adolescent↗
PubMed1992

Contrast-enhanced magnetic resonance imaging of the breast.

Contrast-enhanced magnetic resonance imaging (MRI) of 28 patients with known breast tumors was compared with clinical findings and histopathology, and for 12 of the patients also with mammography. The dynamic measurements performed in 18 patients showed that signal intensity in gradient echo (FFE) images increased rapidly in malignant tumors after contrast injection and reached a plateau level at 1-3 min postcontrast. Fibroadenomas showed slower contrast enhancement continuing throughout the whole examination period of 10 min. The most enhancing parts of the tumors were selected for intensity measurements. The differentiation between malignant and benign tumors in dynamic contrast-enhanced MRI was in accordance with the histopathological findings in all cases. The tumor diameter as measured by MRI showed very good agreement with the size of the tumor specimens. Comparison of tumor size measurements in mammography and MRI showed that MRI had the most accurate correlation to the measured size of the tumor specimens.

Adenocarcinoma, Mucinous↗
PubMed1992

Cerebral magnetic resonance imaging and cerebral computerized tomography for patients with solvent-induced encephalopathy.

To compare the results of cerebral magnetic resonance imaging (MRI) and computerized tomography (CT) for patients with solvent-induced encephalopathy, a parallel study was performed with nine patients. The diagnosis had been given three to five years earlier on the basis of relevant exposure to solvents, findings on neuropsychological tests, a neurological examination, and cerebral CT. There was no progression of pathological lesions from the first to the second CT examination. Four patients with atrophy in the CT examination also had atrophy in the MRI examination. In addition three patients with normal CT findings showed atrophy in the MRI examination. It was concluded that MRI should be the modality of choice whenever diagnostic imaging is necessary in the clinical workout of patients with diagnosed or suspected solvent-induced encephalopathy.

Adult↗
PubMed1991

[Laboratory diagnosis of multiple sclerosis].

In 26 patients with multiple sclerosis 100% responded abnormally to magnetic resonance imaging of the brain. Lesions in the posterior fossa were observed in 18 patients. The auditory brain stem response was abnormal in 15 patients, and 22 had abnormal immunoglobulins in the cerebrospinal fluid. The correlation between abnormalities of the auditory brain stem response and the magnetic resonance images was greatest in a subgroup where the two investigations were performed within a ten day interval. Results from magnetic resonance imaging, evoked potentials and cerebrospinal fluid investigations were used to reclassify 13 of 15 patients with clinically "possible" or "probable" multiple sclerosis to a higher level using Poser's criteria. Evoked potentials (the auditory brain stem response in particular) correlated best with clinical multiple sclerosis category. We recommend that magnetic resonance imaging is established as a first-hand investigation in evaluations of multiple sclerosis. Evoked potentials and cerebrospinal fluid investigations may prove to be more specific, however, and these investigations should also be performed as a routine.

Adult↗
PubMed1991

[Consequences of diagnostics with magnetic tomography].

Physicians referring patients to examinations by magnetic resonance tomography (MT) were asked to answer almost identical questionnaires before and after the examination. The questions referred to diagnosis and planned patient management. Impact of MT was measured by examining the changes in patient diagnoses and planned management after the MT scans. In 33% of the group (400 patients) the main diagnosis (four digit ICD-9 code) changed after MT. Diagnostic security was better for 43%, and further diagnostic follow-up changed for 56%, surgery for 20% and radiation therapy for 11%. MT was assumed to have had real consequences for 33% of the patients in terms of significant changes in the doctors planned management or in his concept of the disease. In a follow-up study 1.5-2 years after MT, 64% of the referring doctors were of the opinion that the MT scan had had consequences for the patient and they placed the emphasis on less active patient follow-up after MT.

Follow-Up Studies↗
PubMed1991

Oral magnetic particles in MR imaging of the abdomen and pelvis.

Two phase 2 clinical trials of an oral superparamagnetic contrast agent for enhancement on magnetic resonance images of the intestine were performed. In trial 1, 31 male patients with cancer of the testis underwent follow-up examinations of the abdomen at 0.5 and 1.5 T after oral administration of magnetic particles. In trial 2, 31 female patients with pelvic and lower abdominal disease were examined at 1.5 T after administration of the contrast material. The patients each ingested 800 mL of contrast material over approximately 2 hours. Concentrations of 0.25 and 0.5 g/L did not induce blurring or metallic artifacts. Distribution was homogeneous through the gastrointestinal tract. In all patients, a loss of signal intensity was observed on proton density-, T1-, and T2-weighted images. The diagnostic information from postcontrast images in trial 2 was greater in 16 patients (52%). Contrast enhancement was independent of field strength; no major side effects were observed. Artifacts from moving bowels were less troublesome, and delineation of intraabdominal and pelvic organs was better with the use of oral magnetic particles.

Abdominal Neoplasms↗
PubMed1988

Cerebral nuclear magnetic resonance (MRI) in Kearns syndrome.

We describe an 11-year-old boy with external ophthalmoplegia, pigment retinopathy, hearing loss, elevated spinal protein and ragged-red fibers on muscle biopsy. Cerebral nuclear magnetic resonance (MRI) demonstrated demyelinating lesions in the white matter of the cerebral hemispheres and the cerebellum. To our knowledge this is the first report on the cerebral MRI findings in Kearns syndrome.

Brain↗
PubMed1975

[Lyell's syndrome].

Explore the source record for details and available documents.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Comparative signal intensity measurements in dynamic gadolinium-enhanced MR mammography.

Increases in signal intensity enhancement were measured in defined regions of interest (ROIs) to allow distinction between malignant and benign tumors with dynamic gadolinium-enhanced magnetic resonance (MR) mammography. Twenty patients with palpable breast lesions (15 malignant, five benign) underwent MR mammography. The dynamic gradient-echo sequence was performed with intravenous bolus injection of gadopentetate dimeglumine and consisted of 25 images with a time resolution of 30 seconds. Contrast enhancement was calculated by comparing user-defined ROIs on pre- and postcontrast images. An increase in signal intensity of 70% or more on the 1-minute postcontrast image was used as the criterion of malignancy. MR mammographic results correlated with histopathologic findings in all patients when the defined ROI was in the most enhancing part of the tumor. For the ROI in areas of submaximal enhancement or when the ROI surrounded the whole lesion, only five and nine tumors, respectively, fulfilled the malignancy criterion. All malignant tumors showed large variations in signal intensity enhancement that depended on the position of the ROI in the tumor. Dynamic, gadolinium-enhanced MR mammography allows distinction of benign from malignant breast tumors when the selected ROI is in the most enhancing part of the lesion.

Breast↗
PubMedDate not supplied

In vivo 1H MRS of normal breast and breast tumors using a dedicated double breast coil.

Image-guided localized proton MR spectroscopy (MRS) of normal breasts and breast tumors (ductal and undifferentiated carcinomas) was performed using a dedicated double breast coil. In vivo 1H MR spectra from 10 normal volunteers showed signals from water and lipids only, even in breasts with small contribution of fatty breast tissue. In the spectra from 6 of the 12 examined patients, an intense signal assigned to choline compounds was detected. The signal was also detected at lower levels in the remaining patients. This study shows that in vivo 1H MRI/MRS examinations of breast tumors can be performed within an examination time of 45 to 60 minutes. Signals from breast tumor metabolites may be detected using in vivo 1H MRS.

Adult↗
PubMedDate not supplied

Comparison between magnetic resonance imaging findings and knee stability: measurements after anterior cruciate ligament repair with and without augmentation. A five- to seven-year followup of 52 patients.

We compared magnetic resonance imaging findings with knee stability measurements in a group of 52 patients 5 to 7 years after repair of an acute anterior cruciate ligament rupture. The patients underwent one of three surgical procedures: nonaugmented repair using the Palmer technique, repair with synthetic augmentation, and repair with biologic augmentation. The appearances of the menisci, subchondral bone, and cartilage were also assessed. Of the patients with clinically stable knees in the nonaugmented repair group, the repaired ligament appeared to be present and intact in 54% (7 of 13) of the patients. In the group with the repair augmented with the ligament augmentation device, 33% (4 of 12) demonstrated repair integrity, whereas in the group with patellar tendon augmentation of the repair, 82% (14 of 17) of the patients with clinically stable knees had intact ligaments on magnetic resonance imaging. Twelve patients had new and complete ruptures of one of the menisci, nine of which occurred in unstable knees. Thirteen patients had subcortical bone changes in the femoral condyles. Eight of these knees had major degenerative cartilage changes overlying the bone changes. Magnetic resonance imaging signals in the repaired ligament augmented with the patellar tendon were highly predictive of clinical stability, but the integrity of the nonaugmented and ligament augmentation device-augmented anterior cruciate ligament repairs did not closely correlate with the clinical findings.

Adolescent↗