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Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 703 records · Page 39Linked to original sources
PubMedDate not supplied

[Imaging of the internal structures of the knee by MR tomography].

With magnetic resonance imaging it is possible to demonstrate the cruciate ligaments of the knee reproducibly without the need for invasive measures. Prerequisites for this are high-resolution coil systems and a stratum thickness of 5 mm or less. Examination of 29 patients and volunteers showed that normal cruciate ligaments can be delineated as homogeneous zones of low signal intensity and high contrast from the surrounding fatty tissue, while in cases of injury to the cruciate ligaments an interruption of the ligament structure, inability to detect them in anatomic position, or an intermediate signal is observed. In 13 cases operated on, with 12 injuries of the cruciate ligaments, the MR findings corresponded to findings at surgery. In 6 patients who had previously had cruciate ligament plasties there correlation with clinical findings was only partial.

Adolescent↗
PubMedDate not supplied

Sex-specific differences of subacromial space width during abduction, with and without muscular activity, and correlation with anthropometric variables.

The objectives of this study were to determine sex-specific differences of the subacromial space width during active and passive arm abduction and to analyze the correlation of this space with general and regional anthropometric variables. Fourteen healthy subjects (7 men, 7 women) were examined with an open magnetic resonance system at 30 degrees and 90 degrees of abduction (with and without muscle activity). After 3-dimensional reconstruction, the minimal acromiohumeral distance, the glenoid size, and the humeral head radius were determined. At 30 degrees of abduction, a significant difference of the acromiohumeral distance was observed between men (8.18 +/- 1.0 mm) and women (6.98 +/- 0.75 mm) (P < .05), but not at 90 degrees (6.7 +/- 2.0 mm versus 5.9 +/- 1.0 mm) or under muscle activity (4.9 +/- 2.4 mm versus 3.5 +/- 2.1 mm). Significant correlations between the acromiohumeral distance and anthropometric variables were found at 30 degrees of abduction (r = 0.48 to 0.72), but not at 90 degrees, with or without muscle activity (r = 0.21 to 0.55). The results demonstrate that at physical rest, the subacromial space width is dependent on sex, but the interindividual variability increases substantially during abduction and under muscle activity.

Adult↗
PubMedDate not supplied

MR-imaging changes of musculoskeletal soft-tissue sarcomas associated with neoadjuvant chemotherapy and hyperthermia.

PURPOSE: To evaluate early changes in musculoskeletal soft-tissue sarcomas under neoadjuvant chemotherapy combined with regional hyperthermia (RHT). PATIENTS AND METHODS: Nineteen consecutive patients with high-grade soft-tissue sarcomas of the musculoskeletal system were treated with neoadjuvant chemotherapy combined with RHT. Patients were imaged, using a high field MR-scanner, before onset of therapy, immediately after one and after four cycles of therapy. The images were evaluated for volume reduction and development of tumour necrosis. In addition, side effects such as surrounding soft-tissue oedema, bleeding and muscle or bone marrow necrosis were analysed. RESULTS: Tumour volume reduction was significant after the completion of neoadjuvant therapy (mean 49%, range 5-91%; (p < 0.001). Extent of tumour necrosis was also significantly different before (mean 22%) and after therapy (mean 58%, p < 0.001). Three patients showed strong tumour necrosis already after one cycle of treatment. Tumour volume reduction was not associated with the extent of pre-existing necrosis or necrosis development. The extent of tumour volume before start of therapy did not affect volume reduction or necrosis induction after therapy. Reduction of tumour oedema was significant after therapy (p < 0.001). No side effects were observed during thermochemotherapy. CONCLUSION: Neoadjuvant chemotherapy combined with RHT resulted in significant tumour volume reduction and induction of tumour necrosis, which can be detected early and monitored closely with MRI.

Adult↗
PubMedDate not supplied

Spirometrically controlled quantitative CT for assessing diffuse parenchymal lung disease.

OBJECTIVE: Assessment of lung attenuation by CT reflects changes in the air-to-tissue ratio of the lung. We have analyzed the interdependence of intrathoracic gas volume, lung morphology, and functional disorder by high resolution CT (HRCT) to assess quantitative disease threshold in obstructive and restrictive diffuse lung disease. MATERIALS AND METHODS: Pulmonary HRCT was performed on 24 healthy volunteers, 11 patients with chronic obstructive pulmonary disease (COPD), and 16 patients with idiopathic lung fibrosis (IPF). HRCT measurement was standardized by taking three scans at the carina +/- 5 cm and by defining inspiration levels by percent vital capacity (VC) via spirometrically gating to the scanner. RESULTS: The mean lung density at 50% VC (DL50) for healthy subjects was -819 +/- 3.8 (mean +/- SEM) HU. In contrast, COPD DL50 was lower, averaging -861 +/- 6.4 HU, and the IPF DL50 was considerably higher (-731 +/- 17.7 HU), both significantly different (p < 0.001) compared with the control group. The accuracy of quantitative HRCT at different inspiration levels was evaluated by scanning the basal layer at 20, 50, and 80% VC. The control values were -747 +/- 5.6, -816 +/- 3.6, and -855 +/- 3.0 HU, respectively, which were significantly higher (p < 0.001) than those seen in COPD patients at 20 and 50% VC. Again, the IPF patients exhibited increased lung density (p < 0.001) at all inspiratory levels. Discrimination power was best among all cohorts at 20 and 50% VC. Position-dependent artifacts on lung density were quantified by the anteroposterior density gradient (APG). Irrespective of the underlying disease, APG at 50 and 80% VC was similar, but was up to twofold higher at 20% VC, indicating that quantitative estimates near RV may misrepresent mean lung density. CONCLUSION: Our data indicate that quantitative HRCT measurements should be performed not near full inspiration or expiration, but at an intermediate degree of lung inflation, e.g., 50% VC, for reasons of accuracy, intra- and intersubjective comparability, and feasibility. We conclude quantitative HRCT to be a sensitive tool for the evaluation of diffuse parenchymal lung disease.

Adult↗
PubMedDate not supplied

Imaging of eye movement with fast MRI.

PURPOSE: Imaging of eye movement disorders has so far been restricted to the semifunctional cine mode of CT and MRI. Since real-time imaging of eye movement is necessary to investigate dynamic disorders, the aim of our study was to implement a fast MR technique to investigate eye movement in a real-time mode. METHOD: Six healthy volunteers and three patients suffering from end-point nystagmus were examined with fast MR sequences while performing the following eye movements: holding different gaze positions, reading a defined text to demonstrate saccadic movements, and holding a primary gaze position and maximal end-point position to cause nystagmus when present. RESULTS: In all cases, we were able to delineate eye movement with fast MRI. Anatomic and functional information could be obtained simultaneously for the first time through observation of saccadic and pursuit eye movements. CONCLUSION: Fast MRI allows for the assessment of dynamic eye movement without the restrictions of cine mode and is able to provide the clinician with additional information in the evaluation of functional movement disorders.

Adult↗
PubMedDate not supplied

Regional relative blood volume MR maps of meningiomas before and after partial embolization.

PURPOSE: Our goal was to evaluate the role of relative blood volume (rBV) measurements in monitoring the embolization effect in meningiomas by using maps of susceptibility-weighted first pass MR data. METHOD: Eighteen examinations of nine patients before and following partial embolization were performed on a 1.5 T scanner. Embolization was achieved by injection of particles (45-150 microns). During dynamic imaging a bolus (0.2 mmol/kg) of gadopentetate dimeglumine was injected. RESULTS: The tumor rBV/gray matter rBV ratio was 3.11 +/- 1.40 for untreated tumors and 0.12 +/- 0.09 for successfully embolized tumors. The regional rBV in embolized meningiomas was significantly lower than that in untreated meningiomas (t test, p < 0.001). Vital tumor tissue showed positive enhancement in T1 and high rBV; nonvital tissue lacked T1 enhancement and bolus effect in the first pass, thus leading to low or missing rBV values. However, we also observed lack of bolus formation despite T1 enhancement (6/9 postembolization regions), possibly due to slow collateral flow. One of the patients treated with embolization bled during surgery. CONCLUSION: Maps of relative regional cerebral BV provide hemodynamic information in meningiomas and monitor the treatment effect of embolization in meningiomas more precisely than T1-weighted contrast-enhanced imaging.

Blood Loss, Surgical↗
PubMedDate not supplied

Intravertebral vacuum phenomenon following fractures: CT study on frequency and etiology.

PURPOSE: The purpose of this work was to determine the frequency and etiology of the intravertebral vacuum phenomenon (IVP). METHOD: CT examinations of 96 vertebral fractures were evaluated for IVP. Bone mineral density (BMD) was determined in nonfractured vertebrae. For calibration purposes, densities of a standard phantom measured in 30 patients who underwent quantitative CT examinations in the same time period were used and precision was calculated. RESULTS: Eleven of 96 fractures (11.5%) showed IVP. IVP was present in 4 of 20 fractures at T12 (20%), in 4 of 23 at L1 (17.4%), and 1 IVP was found at L2-4 each. Mean +/- SD age of patients with IVP was 68.3 +/- 10.5 years and without 47.8 +/- 19.4 years (p < 0.001). Mean +/- SD density of nonaffected vertebra was 45.9 +/- 17.0 mg of hydroxyapatite/ml for patients with IVP and 139.5 +/- 62.6 mg/ml for those without IVP (p < 0.0005). An average precision of 1.2% was calculated for the density measurements over the investigated time. CONCLUSION: Following vertebral fractures, IVP on CT scans is more common than presumed and increases with age. There exists a significant inverse correlation between the BMD and the frequency of IVP.

Age Factors↗
PubMedDate not supplied

Carpal tunnel syndrome: assessment by turbo spin echo, spin echo, and magnetization transfer imaging applied in a low-field MR system.

PURPOSE: The purpose of this work was to evaluate patients with carpal tunnel syndrome (CTS) using a low-field extremity MR system (E-MRI: 0.2 T). METHOD: Twenty-two patients with typical findings of CTS and 30 control persons were imaged on an E-MRI. Axial T2-weighted turbo SE (TSE), T1-weighted SE sequences, and 2D GRE magnetization transfer (MTC) sequences were compared. SE and MTC sequences were obtained before and after contrast agent administration (0.1 mmol/kg body wt of Gd-DTPA). Two readers evaluated typical MR findings of CTS independently. RESULTS: Patients with CTS demonstrated palmar bowing of the flexor retinaculum significantly more often. The normal or edematous median nerve was best identified on TSE and MTC scans (kappa = 0.59 and 0.8). The MTC sequences showed perineural enhancement significantly better than respective T1-weighted SE sequences but were rated second in comparison with T2-weighted TSE scans. CONCLUSION: At low-field strength, median nerve edema is best depicted on T2-weighted TSE sequences, whereas MTC sequences are most sensitive to perineural contrast enhancement.

Carpal Tunnel Syndrome↗
PubMedDate not supplied

Navigator echo-based respiratory gating for three-dimensional MR coronary angiography: reduction of scan time using a slice interpolation technique.

PURPOSE: The aim of the study was to compare a conventional respiratory-gated 3D MR coronary angiographic technique (conventional MRCA) with a respiratory-gated 3D MR coronary angiographic technique that includes a slice interpolation technique (slice interpolation MRCA). Both MRCA techniques were compared based on the quality of visualization of the coronary arteries and the diagnostic accuracy in identifying hemodynamically significant coronary artery stenoses. METHOD: Forty patients with known proximal coronary artery stenosis after conventional CA were examined on a 1.5 T scanner, that is, 20 patients with each sequence. A 6 point grading system (0 = worst quality, 5 = best quality) was used to evaluate and compare the image quality. The length and proximal diameter of the depicted coronary arteries were measured. Detection of coronary artery stenoses was compared with that obtained by conventional CA by two blinded readers. RESULTS: With the slice interpolation technique, the average scan time of the entire heart was reduced by approximately 40%. With use of conventional MRCA, 69% of all proximal and middle coronary artery segments were visualized with a sufficient image quality; with the slice interpolation technique, 79% of these segments were depicted adequately. For the assessment of stenoses, sensitivity was 71% and specificity was 53% for conventional MRCA and 72 and 60% for slice interpolation MRCA, respectively. These differences in sensitivity and specificity were statistically not significant. CONCLUSION: The application of a slice interpolation technique reduces the scan time, maintains a comparable sensitivity and specificity for the assessment of coronary artery stenoses, and increases the number of completely identified coronary artery segments compared with the conventional technique.

Aged↗
PubMedDate not supplied

Parental reactions to children's negative emotions: longitudinal relations to quality of children's social functioning.

Relations between self-reported parental reactions to children's negative emotions (PNRs) and children's socially appropriate/problem behavior and negative emotionality were examined longitudinally. Evidence was consistent with the conclusion that relations between children's externalizing (but not internalizing) emotion and parental punitive reactions to children's negative emotions are bidirectional. Reports of PNRs generally were correlated with low quality of social functioning. In structural models, mother-reported problem behavior at ages 10-12 was at least marginally predicted from mother-reported problem behavior, children's regulation, and parental punitive or distress reactions. Moreover, parental distress and punitive reactions at ages 6-8 predicted reports of children's regulation at ages 8-10, and regulation predicted parental punitive reactions at ages 10-12. Father reports of problem behavior at ages 10-12 were predicted by earlier problem behavior and parental distress or punitive reactions; some of the relations between regulation and parental reactions were similar to those in the models for mother-reported problem behavior. Parental perceptions of their reactions were substantially correlated over 6 years. Some nonsupportive reactions declined in the early to mid-school years, but all increased into late childhood/early adolescence.

Age Factors↗
PubMedDate not supplied

Prediction of elementary school children's externalizing problem behaviors from attentional and behavioral regulation and negative emotionality.

The purpose of this study was to examine the moderating role of individual differences in negative emotionality in the relations of behavioral and attentional (emotional) regulation to externalizing problem behaviors. Teachers' and one parent's reports of children's regulation (attentional and behavioral), emotionality, and problem behavior were obtained when children were in kindergarten to grade 3 and two years later (N = 169; 146 in major analyses); children's behavioral regulation also was assessed with a measure of persistence. According to the best fitting structural equation model, at two ages behavioral dysregulation predicted externalizing behavior problems for children both high and low in negative emotionality, whereas prediction of problem behavior from attentional control was significant only for children prone to negative emotionality. There were unique, additive effects of behavioral and attentional regulation for predicting problem behavior as well as moderating effects of negative emotionality for attentional regulation.

Age Factors↗
PubMedDate not supplied

The relations of regulation and emotionality to children's externalizing and internalizing problem behavior.

The purpose of this study was to examine the relation of different types of negative emotion and regulation and control to 55- to 97-month-olds' internalizing and externalizing problem behaviors. Parents and teachers provided information on children's (N = 214) adjustment, dispositional regulation and control, and emotion, and children's regulation was observed during several behavioral tasks. Internalizing was defined in two ways: as social withdrawal (to avoid overlap of items with measures of emotionality) or, more broadly, as anxiety, depression, and psychosomatic complaints. In general, children with externalizing problems, compared with children with internalizing problems and nondisordered children, were more prone to anger, impulsivity, and low regulation. Children with internalizing symptoms were prone to sadness, low attentional regulation, and low impulsivity. Relations between internalizing problems and emotionality were more frequent when the entire internalizing scale was used. Findings suggest that emotion and regulation are associated with adjustment in systematic ways and that there is an important difference between effortful control and less voluntary modes of control.

Adaptation, Psychological↗
PubMedDate not supplied

The visible animal project: a three-dimensional, digital database for high quality three-dimensional reconstructions.

The "Visible Animal Project" (VAP) is comprised of axial anatomic cryosections and corresponding CT and MR images of a mature dog. The digital database is used for the creation of three-dimensional computer graphics of canine anatomy. The technique of cryodissection is described in detail. The combining of the corresponding CT and MR images, and cryosections as well as the data processing for the creation of three-dimensional reconstructions is presented and examples are shown. For the first time a complete high-resolution three-dimensional database of a dog is available, which can be used as the base for further high quality three-dimensional reconstructions, similar to the "Visible Human Project" (VHP).

Anatomy, Cross-Sectional↗
PubMedDate not supplied

[The value of magnetic resonance tomography (MRT) in inflammatory rheumatic diseases].

As compared to other imaging modalities, magnetic resonance imaging (MRI) is characterized by superior soft tissue contrast, multiplanar display, and lack of ionizing radiation and other hazards. Contrast media, including paramagnetic substances, (e.g., gadolinium-DTPA) are useful for further improvement of diagnostic capabilities of MRI. In this paper the results of MRI in rheumatoid arthritis and related disorders, as well as the potentials of its clinical use are discussed.

Bone and Bones↗
PubMedDate not supplied

Cogan's Syndrome. High resolution MRI indicators of activity.

In the chronic-relapsing form of Cogan's syndrome, it can be difficult to evaluate the activity of the disease. In contrast to the initial stage, routine diagnostic techniques sometimes fail to indicate progression in the chronic stage. To determine whether high-resolution magnetic resonance imaging (HR-MRI) can be used to differentiate between active and inactive stages, we examined three patients with Cogan's syndrome (one during an acute relapse, two with chronic audiovestibular deficits), all of whom had antibodies to inner ear tissue (cochlea, vestibular labyrinth). Unenhanced T1-, T2, gadolinium-enhanced T1-weighted, and three-dimensional constructive interference in steady stage (CISS) images were used. Abnormal MRI signals of the inner ear were related to the activity of the disease. The patient studied during an acute exacerbation showed abnormal MRI signals in the vestibule, semicircular canals, vestibular nerve, and cochlea, which disappeared after the relapse. These abnormalities included high signal in the membranous labyrinth, the vestibule, and cochlea, with enhancement on T1-weighted images, indicating gadolinium leakage through the abnormal labyrinthine membrane into the perilymphatic spaces. In contrast, the other two patients with chronic audiovestibular deficits but no clinical signs of an acute relapse, had narrowing or occlusion of semicircular canals of the cochlea on the 3D-CISS images, but no high signal lesions (T1) and no enhancement. We conclude that sequential gadolinium-enhanced MRI can identify the active stage of Cogan's syndrome. The combination of HR-MRI and antibodies to inner ear antigens are helpful in the diagnosis of acute, sequential, bilateral audiovestibular impairment of autoimmune origin.

Acute Disease↗