Biomedical subjects

J Assheuer

Publications and source records attributed to J Assheuer.

At least 19 recordsLinked to original sources

PubMed2001

[Experimental validation of DXA and MRI-based bone density measurement by ash-method].

Different methods have been established for bone density measurements such as dual energy X-ray absorptiometry (DXA), quantitative computertomography (QCT), and scintigraphy (VQ-Scan). There are hints that magnetic resonance imaging (MRI) might become a new option for the evaluation of bone density. The aim of this study was to investigate correlations between MRI vs. DXA and MRI vs. mineral content of lumbar vertebrae. Data were obtained from ten lumbar vertebral bodies of cattles. The T-1 MRI-sequences SE, PS, and the T-2 Sequence STIR were used for analysis. Total pixel numbers and a pixel per area ratio were determined. Values were compared to DXA-measurements, to the wet weight, and to separated measurements of the spongious, trabecular, and total mineral content of the vertebral body after ashing. We found correlations between DXA (g/vertebral body) vs. mineral content by ash-method (0.918; p < 0.01), DXA vs. MRI (SE-sequence) (-0.872; p < 0.01), and MRI (SE-sequence) vs. mineral content (0.775; p < 0.01). No correlations were found between PS- or STIR-sequences and the ash-method. This study shows that the determination of the bone mineral content of vertebrae is possible applying MRI in the T1-weighted SE-sequence. Without radiation, the MRI provides additionally early detection of trabecular lesions, fractures, and deformities at the spine, without other diagnostic procedures becoming necessary.

Absorptiometry, Photon↗

PubMed1999

MRI of acute cerebral infarcts, increased contrast enhancement with continuous infusion of gadolinium.

We compared contrast enhancement on T1-weighted MRI of acute cerebral infarcts after conventional bolus administration and continuous infusion of gadolinium. We examined 12 patients with a history of acute stroke with contrast-enhanced MRI once a week for a 1 month. Only ischaemic lesions were investigated after cerebral haemorrhage had been excluded by CT. Each MRI study included T2- and proton density-weighted sequences for determination of the size and site of the infarct, immediate postinjection T1-weighted imaging after bolus administration of 0.1 mmol/kg gadolinium-DPTA and delayed T1-weighted imaging after additional continuous infusion of 0.1 mmol/kg over 2 h. A total of 42 MRI studies was performed. In the first week after the onset of stroke, most infarcts (8 of 10) did not enhance after bolus administration, whereas all showed distinct contrast enhancement after the infusion. In the following weeks all but two infarcts showed contrast enhancement after bolus administration; after continuous infusion contrast enhancement could be seen in all cases. While contrast enhancement after bolus administration showed the typical gyriform pattern, enhanced areas were more extensive after the infusion and usually covered the entire infarcted area shown on T2- and proton density-weighted images. We presume that the disturbed blood-brain barrier in ischaemic areas favours delivery of contrast medium to the infarcted tissue if it is offered continuously so that a steady state can develop.

Acute Disease↗

PubMed1999

Assessment of disc injury in subjects exposed to long-term whole-body vibration.

Long-term exposure to whole-body vibration is known to increase the risk of low back problems. The chain of events leading from repeated loading of the lumbar spine to back complaints and the exact nature of the vibration-induced damage are, however, obscure. Fluid in- and outflow as well as viscoelastic deformation are important aspects of the physiological function of the lumbar disc. Precision measurement of stature, termed 'stadiometry', has previously been applied in healthy subjects to document changes in disc height in relation to the load on the lumbar spine. The purpose of this study was to explore the relation between spinal loading and stature in a cohort of 20 subjects with long-term exposure to whole-body vibration. If the change of stature (and thus the change of disc height) caused by changes in spinal loading differed between exposed and normal subjects, this would point to vibration-induced changes in structure and material properties of the discs. For this purpose, four hypotheses were tested: (1) the viscoelastic deformation and fluid exchange of intervertebral discs during phases of spinal loading and unloading differs from normal; (2) the water content of lumbar discs of subjects exposed to long-term whole-body vibration deviates from normal; (3) the mean disc height of the lumbar spine depends on the total time of vibration exposure; (4) repeated loading influences trabecular bone density of vertebrae in the lumbar spine. A cohort of 20 operators of heavy earth-moving machinery was enrolled. Back complaints suspected to be due to long-term exposure (mean 17.6 +/- 2.1 years) to whole-body vibration and application for early retirement were the selection criteria used. Change of stature during a regular 8-h shift and change of stature in standing, carrying and sitting activities were measured. The stadiometric investigations were supplemented by magnetic resonance imaging (MRI) of the lumbar spine to assess whether the water content of the discs exhibited deviations from normal. In addition, quantitative computed tomography (QCT) was performed to assess whether the trabecular bone density of the third lumbar vertebra deviated from normal. The results showed no significant difference in change of stature while standing, carrying or sitting between exposed machine operators and non-exposed operators. Likewise, MRI examinations revealed no significant differences in the water content of the discs averaged over the lumbar spine. In addition, QCT examinations revealed no significant difference in the trabecular bone density of the third lumbar vertebra. The study thus revealed no significant difference between a cohort with long-term exposure and non-exposed controls with respect to viscoelastic properties of discs as determined by stadiometry, average water content of lumbar discs and trabecular bone density of L3.

Adult↗

PubMed1998

Intracerebral haemorrhage from a venous angioma following thrombosis of a draining vein.

We report a case of putaminal haemorrhage from a venous cerebral angioma following thrombosis in a draining vein. The patient complained of numbness of the right side, followed by headache and aphasia. CT demonstrated an intracerebral haemorrhage due to thrombotic occlusion of a draining vein of the venous angioma. Carotid angiography showed the venous angioma. MRI studies confirmed the diagnosis and demonstrated recanalisation of the draining vein following therapy with phenprocoumon.

Brain Neoplasms↗

PubMed1998

The value of magnetic resonance imaging as postoperative control after arthroscopic treatment of osteochondritis dissecans.

The purpose of our study was to evaluate the value of MRI for preoperative arthroscopical planning in patients with osteochondritis dissecans. Based on the experience from 136 patients with osteochondritis dissecans of the knee or the ankle who were arthroscopically operated by retrograde drilling a follow-up study was carried out with 86 of them by clinical, radiological and postoperative magnetic resonance imaging (MRI) examinations. The evaluation was made by means of a visual analogue scale and a score system. The radiological findings were analysed according to the classification of Rodegerdts and Gleissner. The changes based on the MR images were classified according to our own pathoanatomical classification. The total score showed a significant improvement from 63.3 to 79.6 points (knee) and from 50.6 to 70.4 points (ankle). In 72% of the cases, the findings of the MR images showed a defective cartilage surface in the area of the osteochondritis dissecans lesion. An increase of signal in the osteonecrotic area could be seen in 51% of the cases when using a short-time inversion recovery (STIR) image. Especially in patients with postoperative failures, a high percentage of cartilage defects (grade III) could be detected on the MR images (PS 500/10). Uptake of gadolinium-diethylene triamine tetra-acetic acid was regarded as a sign for revascularization. Radiographs did not correlate with these changes detected in the MR images. This retrospective study of an operated osteonecrosis dissecans by MRI provides more detailed information about eventual revascularization of the osteonecrotic area. With this information a more detailed preoperative planing for further cases should be possible.

Adult↗

PubMed1998

The impact of vasoactive substances on intraosseous pressure and blood flow alterations in the femoral head: a study based on magnetic resonance imaging.

In beagle dogs, the alterations of intraosseous pressure and blood supply in the femoral head that result from the administration of vasoactive substances were examined, and the changes were documented by magnetic resonance imaging (MRI). Vasoactive substance were infused into the medial and lateral circumflex femoral arteries of 12 beagle dogs. All infusions were done under standardised conditions with simultaneous measurements of venous blood flow and intraosseous pressure distribution in the proximal femur. The drugs were infused in three cycles of 30 min each separated by 30 min recovery periods, followed by MRI examination at the end of each experiment. At an intraosseous pressure of 14.3 (+/- 4.2) mmHg in the femoral head epiphysis (I), 11.6 (+/- 2.7) mmHg in the greater trochanter (II) and 9.3 (+/- 3.2) mmHg in the femoral shaft (III), a baseline flow of 96.2 (+/- 18.8, n = 12) ml/min was measured in the femoral vein. After infusing bradykinin at a concentration of 10(-6) moles, which is commonly known to lead to cerebral and subcutaneous oedema formation by vessel dilatation, the intraosseous pressure increased to (I): 49.1 (+/- 6.2) mmHg, (II): 42.5 (+/- 5.8) mmHg and (III): 38.3 (+/- 7.1) mmHg in the three measured femoral areas (n = 3). After the bradykinin injection, femoral vein flow increased to a peak value of 238.4 (+/- 43.4) ml/min and then dropped to 62.3 (+/- 14.2) ml/min after discontinuation of the bradykinin infusion. In a second and third series of tests, hyperosmolar (20% NaCl) and hypo-osmolar (distilled water) solutions were applied, also resulting in increased but lower mean intraosseous pressure values (17.3 +/- 4.1 and 25.7 +/- 5.1 ml/min, respectively) in all regions. When administering bradykinin, MRI scans taken immediately after completion of the experiment showed substantial oedema in the femoral muscular system, but without any changes of osseous signals in T1- or short time inversion recovery (STIR)-weighted images, nor did any changes occur when solutions of 20% NaCl or distilled H2O were injected. The results of our experiments demonstrate that acute increases of intraosseous pressure do not cause MRI signal alterations. We therefore conclude that in addition to the described pressure increase, other intraosseous alterations must occur to lead to the detectable signal changes found among patients with diagnosed femoral head necrosis. Finally, the short time period between the rise in intraosseous pressure and performing a conventional MRI may be one reason for missing the development of an intraosseous oedema. On the other hand, conventional MRI might have additional disadvantages for detecting intraosseous fluid compared with a dynamic imaging modality.

Animals↗

PubMed1998

[MRI-controlled facet block--technique and initial results].

In a clinical study, 5 patients with chronic low back pain were treated by MR-guided facet injection of the motion segments L4/L5 and L5/S1. For the infiltration, special nonmagnetic needles were used. The investigations were carried out in an MR unit having a field strength of 1.0 tesla. In all patients, MR visualisation of the facet joints and measurement of the distance to the reference point was readily accomplished. Placement of the special MR needle, however, proved difficult in situations in which the needle had to be advanced through dense fibrous tissue. Nevertheless, the needle was successfully placed at the first attempt in two patients; in all other patients a second attempt was necessary. The entire procedure took about 30 to 40 minutes per patient. The needles were identified without any artefacts. All the patients were pain-free for at least 3 weeks after injection.

Adult↗

PubMed1997

Technetium-99m-HMPAO brain SPECT in patients with syndrome X.

Ninety-five patients with syndrome X were studied by brain single-photon emission computed tomographic examination; 72 (76%) had pathologic findings suggestive of cerebral perfusion abnormalities. These findings support the hypothesis of a vascular disorder not confined to cardiac vessels.

Brain↗

PubMed1997

Avascular osteonecrosis of the acetabulum.

OBJECTIVE: To investigate the possible occurrence of osteonecrosis in the acetabulum in patients with non-traumatic necrosis of the femoral head. DESIGN AND PATIENTS: One hundred and seventy-nine patients with non-traumatic femoral head necrosis were assessed by MRI and radiography for the presence of acetabular necrosis. Three criteria were established to differentiate between osteonecrosis and osteoarthritic changes: (1) heterogeneous morphology and irregular contours of the lesion; (2) typical demarcation lines of osteonecrosis; (3) deficient accumulation of intravenous gadolinium in the affected regions. RESULTS: In four patients histological confirmation of acetabular necrosis was obtained. The MR analysis of 22 acetabula (9.5% of those examined) showed changes which suggested osteonecrosis. No cystic lesions were demonstrated in the subchondral bone of any patient. Two cases of acetabular necrosis were found without an ipsilateral femoral head necrosis. In two patients of the 14 who had undergone total hip replacement following necrosis of the femoral head, aseptic loosening of the acetabular component was found. CONCLUSION: The study suggests that acetabular necrosis may be an accompaniment to aseptic necrosis of the femoral head. Further work is required to assess its importance in premature loosening of the acetabular element of total hip arthroplasty.

Acetabulum↗

PubMed1996

Age-related magnetic resonance imaging morphology of the menisci in asymptomatic individuals.

In 82 asymptomatic subjects aged 8-62 years we evaluated the menisci by magnetic resonance imaging (MRI). Using a 1.0-tesla imager spin-echo sequences (SE 700/20), partial-saturation sequences (500/10), and short-time inversion-recovery sequences (1600/130/30) were performed. For grading the degeneration of the meniscus, a standard classification (grades 0-4) was used. Positive MRI findings correlated with the patients' age. In SE sequences, a grade 0 meniscus was found in 45.5% of all cases, grade 1 in 33.2%, grade 2 in 16.1%, grade 3 in 4.5%, and grade 4 in 0.7%. In PS sequences, we found grade 0 in 23.9%, grade 1 in 27.5%, grade 2 in 31.5%, grade 3 in 15.9%, and grade 4 in 1.1%. In STIR sequences, we found grade 0 in 56%, grade 1 in 25.4%, grade 2 in 11.1%, grade 3 in 6%, and grade 4 in 1.6%. Correlation of meniscus degeneration with subjects' age showed an increase of grade 3 and 4 lesions with advancing age. Subjects older than 50 years presented with grade 3 and 4 lesions in the SE sequence in 28.5% of the cases, in PS sequences in 40.7%, and in STIR sequences in 25%. In asymptomatic subjects, MRI shows an increasing prevalence of meniscal alterations which correlates with age. Especially in subjects older than 50 years, a significant number of meniscal tears must be expected. This shows the potential danger of the use of MRI alone as a basis for the determination of surgical intervention.

Adolescent↗

PubMed1995

Haemodynamic changes in lumbar nerve root entrapment due to stenosis and/or herniated disc of the lumbar spinal canal--a magnetic resonance imaging study.

A prospective MRI study was carried out to assess the secondary changes in patients with stenosis and/or herniated disc of the lumbar spinal canal. The study covered 100 patients who had low back and leg pain due to such processes. Of these, 60 patients (group A) had a monoradicular pain pattern, average duration 2 months, due to a herniated lumbar disc. The remaining 40 patients (group B) had acute exacerbation of their chronic low back and leg pain, due to stenosis and herniated disc. As a control group, 5 asymptomatic volunteers with neither stenosis nor herniated disc on MRI were examined. All the patients and volunteers were examined by MRI with several sequences: partial saturation recovery with phase contrast PS (500/10), spin echo SE (500/20), short TI inversion recovery STIR (1900/135/30) and, for the dynamic study, field-gradient echo sequences FAST (50/15): 10 frames in 200 s. In all participants, Gd-DTPA was administered intravenously. In 8 of the patients of group B capillarisation in the protruded nucleus tissue was demonstrated on the PS sequence after Gd-DTPA administration. This tissue also showed decreased signal intensity on the STIR sequence. The capillarisation extended into the centre of the disc. Venous stasis could be verified in all of the 100 patients. An oedema could be verified in all patients of group A; in 20%, its size exceeded that of the herniated disc. In group B, an oedema was seen in only 12 patients. In the control group, no haemodynamic changes were seen. Using MRI, it is possible to define the border between herniated disc tissue and perifocal oedema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Discitis after procedures on the intervertebral disc.

STUDY DESIGN: Discitis after discectomy is frequently missed or detected too late because of false interpretation of postoperative complaints and examinations. Prospectively, the authors examined 31 patients after single-level discectomies. The results were compared with four clinical cases of postoperative infection. METHODS: From the first to tenth postoperative day, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and temperature were measured. On the fifth or sixth day, magnetic resonance examination was performed with and without administration of gadolinium diethylene triamine penta-acetic acid (Gd-DTPA). All patients were included in follow-up, which included radiographic and clinical examinations, for 3 years. RESULTS: Thirty of thirty-one patients had CRP values less than 2.5 micrograms/mL, ESR values less than 45 mm/hr, and temperatures less than or equal to 37.5 C. Magnetic resonance imaging showed normal postoperative features. Four patients with infection had increased levels of CRP, ESR, and temperature. Magnetic resonance imaging showed retrodiscal infection and spondylodiscitis. CONCLUSION: After discectomies, CRP, ESR, and temperature should be measured from the third day on. Pathologic values should initiate magnetic resonance examination. In cases of retrodiscal infection or discitis, conservative treatment with antibiotics is sufficient. In cases of retrodiscal abscess, operative intervention should be considered.

Adult↗

PubMed1994

Strain-related long-term changes in the menisci in asymptomatic athletes.

UNLABELLED: In 82 asymptomatic subjects aged 8-62 years we evaluated the menisci by magnetic resonance imaging [MRI; 1.0 tesla; spin-echo (SE 700/20), PS (partial saturation; 500/10), STIR (short time inversion recovery sequence; 1600/130/30)]. For grading the degeneration of the meniscus we used a standard classification (grades 0-4). MR findings were correlated with the patients' age, weight, profession, and athletic activity. Statistic analysis revealed a correlation between athletic activity and meniscal degeneration of both anterior horns and the posterior horn of the lateral meniscus. Especially the anterior horn of the lateral meniscus seems to be loaded during athletic activities. Correlation of meniscus degeneration with subjects' age showed an increase in grade 3 and grade 4 lesions with advancing age. Among subjects older than 50 years, grade 3 and 4 lesions were present in the SE sequence in 28.5% of cases, in PS sequences in 40.7% of case, and in STIR sequences in 25% of cases. CLINICAL RELEVANCE: Athletic activity seems to load the anterior knee compartments, especially the lateral compartment. MRI shows meniscal lesions in a significant number of asymptomatic subjects, especially those older than 50 years.

Adolescent↗

PubMed1994

Long-term changes in the magnetic resonance image after chemonucleolysis.

After treatment of a symptomatic herniated disc with chymopapain, 14 patients were re-examined by magnetic resonance imaging (MRI) at a mean follow-up of 72 months. Well-defined MRI findings before chemonucleolysis were compared with those after the procedure by an independent observer. Five MRI parameters were assessed. No significant change was noted in the signal intensity of the affected disc, the extent of osteochondrosis and endplate reaction of the affected segment. The height of the affected disc as well as the size of the disc herniation were reduced significantly. The loss of the height is seen as a direct result of chymopapain activity, whereas the alteration of the size of the herniation seems to depend on the natural history of a disc herniation and is probably not a simple result of the treatment.

Adult↗

PubMed1994

[Stress-related long-term changes of the menisci].

UNLABELLED: In 82 asymptomatic subjects aged 8 to 62 years we evaluated the menisci by MRI (1.0 tesla; Spin-Echo (SE 700/20), PS (Partial Saturation) (500/10), STIR (Short-Time-Inversion-Recovery-Sequence; 1600/130/30). For grading the degeneration of the meniscus we used a standard classification (grade 0-4). MR-findings were correlated with the patients' age, weight, profession, and athletic activity. Statistic analysis revealed a correlation between athletic activity and meniscal degeneration of the anterior horns as well as of the lateral meniscus. Especially the anterior horn of the lateral meniscus seems to be loaded during athletic activities. Correlation of meniscus degeneration with subjects' age showed an increase of grade 3 and grade 4 lesions with advancing age. Subjects older than 50 years presented grade 3 and 4 lesions in the SE-sequence in 28.5% of the cases, in PS-sequences in 40.7% of the cases, and in STIR-sequences in 25% of the cases. CLINICAL RELEVANCE: Athletic activity seems to load the anterior knee compartments especially the lateral compartment. In asymptomatic subjects MRI shows meniscal lesions in a significant number of patients, especially in subjects older than 50 years.

Adolescent↗

PubMed1994

[Does intravenous gadolinium-DTPA administration have advantages in magnetic resonance imaging of acute injuries or chronic damage to the knee joint?].

79 patients with acute or chronic lesions of the knee were evaluated by MRI prior to and after application of Gd-DTPA. The MRI examination was performed by a 1.0 tesla imager with SE as well as FEDIF sequences. These MR studies were compared prior to and after intravenous Gd-DTPA application, focusing on the visibility and the definition of a possible lesion, and scored with a 3-point score. Statistic analysis and case analysis revealed that in patients with meniscus degeneration without a tear, Gd application yields no additional diagnostic information. However, in patients with meniscus tears Gd-DTPA significantly facilitates the definition of the lesion. Furthermore, Gd-DTPA makes differentiation possible between the synovial fluid and the synovial membrane. Whereas in cases with capsule or collateral ligament tears Gd-DTPA facilitates the documentation of the lesion, we found no advantage in using Gd-DPTA in patients with ACL tears. In patients with chondropathia patellae Gd-DTPA application supports the visualization of the secondary synovial reaction.

Anterior Cruciate Ligament↗

PubMed1993

Pontine infarction in acute posterior multifocal placoid pigment epitheliopathy.

In a patient with acute posterior multifocal placoid pigment epitheliopathy (APMPPE), a pontine infarction occurred about 6 months after the ophthalmological manifestation. We report the first case with histopathologically proven vasculitis shown by muscle biopsy and the first positron emission tomographic documentation in APMPPE. The ophthalmological and cerebral symptoms responded well to steroid treatment. Long-term immunosuppression (e.g. azathioprine 1-2 mg/kg) seems to decrease the risk of recurrent systemic vasculitis.

Acute Disease↗

PubMed1993

[Magnetic resonance morphologic changes in shoulder joints of world class water polo players].

UNLABELLED: In a prospective study we examined the dominant shoulder of 11 athletes from the 1992 German Olympic water polo team. Their mean age was 25.4 +/- 3.5 years. Water polo had been practised generally for 14.1 +/- 4.3 years and professionally for 11.6 +/- 3.9 years. The weekly training amounted to between 12.5 and 19.5 hours. All athletes were submitted to standardised clinical, sonographical and MRI tests. In 5 cases we found anamnestic and/or clinical indications of rotator cuff pathology. In all 5 cases the supraspinatus tendon was affected, and in three cases both the supra- and the infraspinatus tendon were involved. Sonographically, no specific pathology except a thickened rotator cuff was seen. Remarkable changes were revealed by magnetic resonance imaging. In 8 cases changes were present in the insertion of the rotator cuff at the humeral head. The subacromial bursa was not pathologic. The tendon of the long head of the biceps was pathologically changed in 9 cases. In 7 athletes a so-called biceps halo and in two an osteophyte in the area of the bicipital groove was visible. In all of the 11 dominant shoulder joints massive hypertrophy of the articular capsule and pathologic changes of the anterior glenoid labrum existed. Occult osseous lesions were detected in 5 athletes, and osseous lesions of the humeral head in 8 athletes. In all athletes we could document degenerative changes at the acromioclavicular joints such as effusion in 7 cases, arthritis in two cases, and evident synovitis in two cases. CLINICAL RELEVANCE: Many of the changes detected by MRI were not symptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromioclavicular Joint↗