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M Seiderer

Publications and source records attributed to M Seiderer.

At least 19 recordsLinked to original sources
PubMed1999

MRI of bone marrow: opposed-phase gradient-echo sequences with long repetition time.

Signal intensity for opposed-phase gradient-echo (GE) sequences of tissues composed of fat- and water-equivalent cells such as red bone marrow is extremely sensitive to variation of the ratio of both cell populations (fat-to-water ratio QF/W). Because most bone marrow pathology results in variation of QF/W, GE sequences are characterized by high-contrast imaging of pathology. The aim of this study was to evaluate the influence of TR, TE, FA, QF/W and histology on signal intensity. Signal intensity of opposed-phase GE sequences as a function of TR, TE, FA, and QF/W was measured for a fat-water phantom and cadaver specimens of normal bone marrow (red and yellow) and pathological bone marrow (tumors). All specimens were correlated to histology. Opposed-phase GE imaging of red bone marrow pathology results in low-signal-intensity imaging of intact red bone marrow and high-signal-intensity positive contrast imaging of pathology associated with a change in QF/W. In first-order approximation the signal intensity of pathology is linearly correlated to the change in QF/W. Opposed-phase GE imaging is a sensitive imaging technique for red bone marrow pathology. Relative contrast of red bone marrow pathology is similar to fat-suppressed imaging techniques. Acquisition time is identical to T1-weighted SE sequences.

Bone Marrow↗
PubMed1996

Degenerative disk vascularization on MRI: correlation with clinical and histopathologic findings.

OBJECTIVE: This prospective study was designed to determine the MRI features, clinical significance, and correlation to histopathologic findings of secondary vascularized degenerative intervertebral disks. MATERIALS AND METHODS: Fifty-three patients with localized painful spine syndrome were investigated prospectively by contrast-enhanced MRI. Pain was not predominantly radiating and there was no clinical evidence of spinal infection. In all patients sagittal SE T1-weighted, fast SE T2-weighted or turbo-STIR, and T1-weighted frequency-selective fat-suppressed images were obtained. RESULTS: We identified 37 vascularized disks in 26 patients. In 18 patients the changes had occurred spontaneously, in 6, the affected disk had been operated on previously, and 2 patients had spondylolisthesis. In 15 patients, vascularization was accompanied by medullary edema adjacent to the vertebral endplates. In one of the vascularized disks, herniation was also found. In seven patients, ventral diskectomy was performed. Histopathologic findings confirmed disk vascularization in six of seven cases. CONCLUSIONS: Degenerative, band-like disk vascularization is a feature which is associated with local pain. It was demonstrated by contrast-enhanced MRI. Degenerative disk vascularization is an important differential diagnosis to bacterial spondylodiskitis. It can be a cause of pain in patients with postdiskectomy syndrome.

Diagnosis, Differential↗
PubMed1994

[The nuclear magnetic tomographic diagnosis of focal lesions of the red bone marrow. The optimization of the acquisition parameters for GE and SE sequences].

Gradient-echo (GE) imaging with repetition times equivalent to those of T1-weighted spin-echo (SE) sequences and echo times for antiphase (opposed) transverse magnetisation have proved to be sensitive for high contrast imaging of focal lesions of red bone marrow. The sensitivity of antiphase GE sequences is due to the chemical shift between water-bound and fat-bound protons which introduces a tissue parameter that is not accessible by SE sequences. Main advantage of these GE sequences is the low signal intensity of intact red marrow and the high signal intensity of tumours and inflammatory lesions which allows, similar to T2-weighted SE sequences, for positive contrast imaging of lesions. In order to evaluate and to optimise the contrast-to-noise ratio (CNR) for red bone marrow and tumour 200 GE and 40 SE sequences with repetition times (TR) between 100 and 900 ms, echo times (TE) between 14 and 21 ms and flip angles (alpha) between 10 and 90 degrees were studied. CNR was measured and optimized regarding TR, TE, and alpha. The results indicate that opposed GE sequences, relatively independent from TR and alpha, are characterized by a high contrast-to-noise ratio. According to their high sensitivity for lesion detection they are suited to replace T2-weighted SE sequences.

Artifacts↗
PubMed1993

["Inflammatory" disk degeneration. Magnetic resonance tomographic clinical picture].

Disc degeneration, if it appears relatively early, progresses rapidly with inadequate bone compensation for stabilisation of the area, or in the presence of anatomic variation of the vertebrae with short sagittal diameters, there may be tissue proliferation and edema in the bone marrow and vascular granulations within the disc. We demonstrated these changes in 17 patients by means of MRT which shows edema of the bone marrow and contrast enhancement within the disc. All these patients had severe symptoms. There were no significant neurological findings since in general there was no disc prolapse. The MRT characteristics of this condition are described and correlated with the clinical and radiological features. The use of Gd-DTPA and subtractive spin-echo and gradient-echo sequences in the differential diagnosis from infective discitis is discussed.

Adult↗
PubMed1992

[The nuclear magnetic resonance tomographic differentiation of osteoporotic and tumor-related vertebral fractures. The value of subtractive TR gradient-echo sequences, STIR sequences and Gd-DTPA].

42 patients with known malignancy and vertebral compressions underwent MRI. Sagittal T1-weighted spin-echo images pre and post Gd-DTPA, out of phase long TR gradient-echo images (GE) and short T1 inversion recovery images (STIR) were obtained at 1.0 T. The results were confirmed by histology (6/42) or clinical data (28/42) and follow up MRI studies (8/42). In 39 of 42 cases a correct differentiation between osteoporotic and tumorous vertebral compression fractures was possible by quantification and correlation of SE and GE signal intensities. Gd-DTPA did not improve differential diagnosis, since both tumour infiltration and bone marrow oedema in acute compression fracture showed comparable enhancement. STIR-sequences were most sensitive for pathology but unspecific due to a comparable amount of water in tumour tissue and bone marrow oedema. Susceptibility-induced signal reduction in GE images and morphologic criteria proved to be most reliable for differentiation of benign and tumour-related fractures. In the rare cases of single and nearly complete vertebral compressions with complete loss of bone marrow, differentiation with MRI was not possible.

Contrast Media↗
PubMed1992

[MRT of epiphyseolysis capitis femoris].

MR imaging provides exact measurement of the epiphyseal angle by drawing a ventral tangent to the femoral neck in parasagittal images along the femoral neck. The average MR imaging angle was 49.7 degrees in SCFE. Important information is provided about the activity of the slipping process (reattachment) and the contralateral epiphysis.

Adolescent↗
PubMed1992

[MRT in osteomyelitis: detection of bone sequestration with Gd-DTPA].

In 4/12 patients with subacute or chronic osteomyelitis MRI was able to detect bone sequestrae by use of gadolinium DTPA. This method is of great advantage in cases of infections not originating from osteosynthetic material. In patients in whom osteosynthetic material was removed completely, invisible metallic residuals may lead to signal deterioration.

Contrast Media↗
PubMed1992

Phase III clinical studies with gadoteridol for the evaluation of neurologic pathology. A European perspective.

OBJECTIVES AND RATIONALE: The use of paramagnetic contrast agents has improved the diagnostic sensitivity and specificity of magnetic resonance imaging (MRI) for evaluating diseases of the central nervous system. To assess the safety and imaging properties of the nonionic, gadolinium-based MRI contrast agent gadoteridol, 151 patients and controls were evaluated for safety, and 118 patients with cerebral or spinal pathology were evaluated for imaging efficacy. METHODS: Precontrast T1- and T2-weighted spin-echo images and postcontrast (0.10 mmol/kg) T1-weighted spin-echo images were read by unblinded investigators at each site. RESULTS: The rate of adverse events possibly or probably related to gadoteridol was 4.0% (vasodilation [facial flushing], 1 patient; nausea, 3 patients; urticaria, 2 patients). Laboratory changes were reported in 6.0%. None of these events or changes was considered to be clinically significant. Contrast enhancement was noted in 75% of cases with brain pathology and 64% of cases involving spine lesions. CONCLUSIONS: Gadoteridol is safe in routine clinical use at a dose of 0.10 mmol/kg and provides improved lesion detection compared to plain MRI.

Brain↗
PubMed1991

[MRT in dialysis-associated destructive spondylarthropathy of the atlantoaxial region].

Destructive bone and joint diseases in patients on longterm haemodialysis increase in frequency and are often caused by beta 2-microglobulin-related amyloid deposits. Due to the excellent visualisation of amyloid, MRI with T1-weighted and out-of-phase gradient recalled long TR images is the diagnostic modality of choice. 5 patients, 13 to 21 years on haemodialysis, were investigated. In four patients we found involvement of the atlantoaxial region, one patient was asymptomatic, the other three had severe neurological deficiencies.

Adult↗
PubMed1991

Beta 2 microglobulin-related amyloidosis causing atlantoaxial spondylarthropathy with spinal-cord compression in haemodialysis patients: detection by MRI.

Bone destruction due to beta-2 microglobulin (beta 2-M)-related amyloid deposition is becoming more frequently observed in long-term haemodialysis patients. We report five cases in an unusual site, the upper cervical spine. All patients had been on haemodialysis for more than 13 years and presented with progressive spinal-cord involvement in the region of the first and second cervical nerves. While conventional X-rays and CT scans showed only minor vertebral destruction, MRI disclosed a tumour-like mass within the upper spinal canal, best seen with long TR gradient recalled images. One patient required urgent surgical intervention because of severe spinal-cord compression, and the material was shown to be typically beta 2-M-related amyloid.

Adult↗
PubMed1990

[3D-MR-angiography using Gd-DTPA].

Projection angiograms similar to DSA can be obtained via 3D-gradient echo techniques by subtraction of data sets acquired before and after the intravenous administration of Gd-DTPA (0.1-0.2 mmol/kg body weight). As Gd-DTPA does not penetrate the blood-brain barrier, image subtraction results in complete cancellation of non vascular tissue. In organs without blood-brain barrier Gd-DTPA induced signal enhancement results in modest background superposition of vascular anatomy. With Gd-DTPA angiography vessels are imaged favouring the venous system because of the more constant flow velocity and the lack of ECG synchronization. Gd-DTPA angiography results in high signal-to-noise angiograms and can even be performed with MR imagers which do not meet the hardware requirements for angiography based on flow compensated gradients.

Blood Vessels↗
PubMed1989

Detection and quantification of chronic cerebrovascular disease: comparison of MR imaging, SPECT, and CT.

Twenty patients with angiographically proved occlusion of the internal carotid artery (ICA) (19 unilateral, one bilateral) were studied with magnetic resonance (MR) imaging, iodine-123 iodoamphetamine (IMP) single photon emission computed tomography (SPECT), xenon-133 SPECT, and computed tomography (CT). All patients had a history of stroke or prolonged reversible ischemic neurologic deficit for more than 4 weeks. By regions of interest, T1, T2, regional cerebral blood flow (rCBF), and the number and size of the lesions were determined. The data were expressed as interhemispheric ratios (diseased/nondiseased). The highest ratios obtained were for MR imaging (T1, 2.60 +/- 0.42; T2, 1.61 +/- 0.22 [mean +/- standard deviation]) followed by Xe-133 SPECT (0.58 +/- 0.13) and IMP SPECT (0.56 +/- 0.13). Correlation coefficients for MR imaging (1/T1, 1/T2) and IMP SPECT were below .21. The lesion size was greatest on IMP SPECT images, intermediate on MR images, and least on CT scans. However, MR imaging was superior in detection of pathologic areas (detection rates: MR, 100%; IMP SPECT, 91%; CT, 79%). Relaxation times do not correlate with rCBF.

Brain↗
PubMed1988

[ECG-triggered magnetic resonance tomographic measurement of blood flow velocity in the carotid arteries: comparison with duplex sonography].

Blood flow velocity in the common carotid arteries was measured for 30 vessels by MRI with a multiecho SE-sequence and compared with the results from duplex ultrasound. MR blood flow velocity was measured for a time interval of 390 ms every 30 ms using a EKG-triggered data acquisition. The time-velocity curves measured by MRI and duplex ultrasound were in good agreement. The correlation coefficient for the peak velocity was r = 0.83. Mean peak velocity as measured by MRI was 59 +/- 8% of peak velocity as measured by duplex ultrasound.

Blood Flow Velocity↗
PubMed1988

[High resolution MR angiography with rephasing and dephasing sequences for selective vascular imaging of arteries and veins].

With rephasing and dephasing sequences the vascular system is imaged with high or low signal intensity whereas stationary tissue is imaged with identical signal intensity. With images recorded in systole and diastole followed by image subtraction separate imaging of arteries or veins without background superposition is possible. 13 patients with vascular lesions of the lower extremities and 7 volunteers were examined. Vascular stenosis, aneurysm, dilatation, occlusion and collateral vessels could be imaged similar to digital subtraction angiography. Vessels with a diameter down to 1 mm could be imaged. The large slice thickness up to 80 mm results in projection type images where the vascular tree is imaged over the whole field of view and without partial volume effects.

Arteries↗
PubMed1988

[Anesthesia for magnetic resonance tomography].

Monitoring of the vital signs and the possibility of respiratory support are necessary conditions for the application of magnetic resonance imaging to infants and geriatric patients as well as during intensive care therapy. Since April 1986, 73 patients have been scanned under general anesthesia with controlled artificial ventilation in the Grosshadern University Hospital. For the first time, the ventilator could be placed in the vicinity of the magnetic resonance imaging scanner. With this system, the anesthesiologist is able to inspect the patient, ventilator, and monitoring unit from one place in the examination room.

Adolescent↗
PubMed1986

[Effect of types of field used in nuclear magnetic resonance tomography on core and surface temperature in the human body. Results of in vitro and in vivo experiments].

Deep and superficial body temperature was measured by in vitro and in vivo experiments, using a fluoro-optic procedure and a variety of magnetic and electromagnetic fields in the course of magnetic resonance tomography. The in vitro experiments had shown that measured temperature changes resulting from a static magnetic field were reversible and could be reproduced readily. Temperature measurements in the human body were carried out centrally (oesophageal and rectal measurements) and at the periphery (intravascular). In vivo experiments on 30 experimental subjects showed no significant changes (p = 0.05) in central or surface temperatures as a result of static or dynamic magnetic fields or electromagnetic high frequency fields.

Body Temperature↗
PubMed1986

[Gd-DTPA in magnetic resonance diagnosis of chronic myocardial infarct].

30 patients with myocardial infarction older than three weeks were examined by MRI prior and following intravenous injection of 0.1-0.2 mmol/kg Gd-DTPA, 201TL-SPECT and cineventriculography. Gd-DTPA did not cause any significant change (p less than 0.05) of T2-values for infarcted or non-infarcted myocardium. Compared with this, signal intensity for T1-weighted images increased after the application of the contrast agent both for normal (26 +/- 14%) and infarcted myocardium (33 +/- 16%). The intraindividual signal intensity ratio for infarcted and normal myocardium increased from 1.06 +/- 0.07 to 1.12 +/- 0.09 after the injection of Gd-DTPA. The diagnosis of myocardial infarction by visual analysis of signal intensity was not possible in individual cases. Myocardial infarction could only be visualized indirectly by morphological changes such as wall thinning and aneurysm.

Adult↗