Biomedical subjects

F Schick

Publications and source records attributed to F Schick.

131 records · Page 8Linked to original sources

PubMedDate not supplied

Subtle bone marrow edema assessed by frequency selective chemical shift MRI.

Subtle edema in yellow bone marrow from tumors (14 subjects) and osteomyelitis (9 subjects) were examined by selective nonexcitation (SENEX) water imaging using a short five pulse frequency selective excitation with lipid suppression greater than 96%. Standard spin-echo (SE) proton density-, T1- and T2-weighted images, and fat suppression methods such as short inversion time inversion recovery and also the chemical shift selective Dixon method are discussed in comparison with SENEX. Application of the SENEX method is described and images from four typical cases are demonstrated. Sensitivity to edema is obviously better using the SENEX chemical shift selective method than using other imaging techniques. Improved delineation of abnormal areas in yellow bone marrow is provided by SENEX water imaging in one slice after multislice standard imaging. After shimming, only one SE scan with frequency selective excitation is necessary to get a pure water image.

Adult↗

PubMedDate not supplied

Pulsed magnetization transfer contrast MRI by a sequence with water selective excitation.

OBJECTIVE: A water selective SE imaging sequence was developed providing suitable properties for the assessment of magnetization transfer (MT) effects in tissues with considerable amounts of fat. MATERIALS AND METHODS: The sequence with water selective excitation and slice selective refocusing combines the following features: The RF exposure on the macromolecular protons is relatively low for single slice imaging without MT prepulses, since no additional pulses for fat saturation are necessary. Water selection by frequency selective excitation diminishes faults in the subtraction of images recorded with and without MT prepulses (which might arise from movements). RESULTS: High differences in the signal amplitudes from hyaline cartilage and muscle tissue were obtained comparing images recorded with irradiation of the series of prepulses for MT and those lacking MT prepulses. Utilizations of the described water selective approach for the assessment of MT effects in lesions of cartilage and bone are demonstrated. MT saturation was also examined in muscles with fatty degeneration of patients suffering from progressive muscular dystrophy. CONCLUSION: The described technique allows determination of MT effects with good precision in a single slice, especially in regions with dominating fat signals.

Adipose Tissue↗

PubMedDate not supplied

[Examination of trabecular bone structures of the foot skeleton with MRI imaging].

AIMS: To assess trabecular density and structures at various cancellous bone sites in the foot using MR imaging. To compare the MRI findings with the bone mineral density (BMD) values obtained by quantitative computed tomography (QCT) in the lumbar vertebrae. MATERIALS AND METHODS: Bone mineral densities were measured by QCT in lumbar vertebrae 1 to 3 in ten patients with suspected osteoporosis. Sagittal images of the feet were obtained from these patients and also from seven healthy volunteers applying spin-echo and gradient-echo MR techniques. RESULTS: MR imaging revealed differences between patients with osteoporosis and individuals with healthy bones. Comparison of MR and BMD data revealed a significant dependence of MR data on the bone density measured by QCT (alpha < 0.05). In addition, a good correlation (r = 0.73) was found between the results of the different MRI techniques. CONCLUSIONS: The MR imaging techniques investigated offer an interesting tool for the non-invasive assessment of bony structures, at least at peripheral locations with yellow bone marrow. To enable reliable application in the clinical routine setting, additional studies are required to identify suitable standardized methods and establish normal ranges.

Adult↗

PubMedDate not supplied

Lipid selective MR imaging and localized 1H spectroscopy of bone marrow during therapy of leukemia.

In most patients with acute leukemia very low or absent lipid signals from central red bone marrow are detected using magnetic resonance (MR) techniques, in contrast to healthy persons with considerable signals from both, water and lipid protons. The proliferation of the malignant leukemic cells causes the displacement of fat cells in the marrow. This disorder is reversible during successful cytotoxic chemotherapy of acute leukemia: Lipid signals from vertebral bodies arise again due to the replacement of hypercellular leukemic marrow by fat. Different approaches for lipid selective MR imaging and spectroscopy are reported and results from typical examples are demonstrated and discussed. The report is based on examinations of 12 patients with leukemia in follow-up studies, 11 patients with other disorders of bone marrow, and 26 healthy volunteers.

Adolescent↗

PubMedDate not supplied

Lipids in bone tumors assessed by magnetic resonance: chemical shift imaging and proton spectroscopy in vivo.

The methods of fat and water selective magnetic resonance (MR) imaging and localized 1H MR spectroscopy were evaluated in the course of 37 examinations on 27 primary bone tumors. These methods are capable of demonstrating small amounts of lipids inside the tumors and subtle edema in the adacent bone marrow, in contrast to the usually applied spin-echo and gradient-echo sequences providing signals dependent on the total proton density and on the relaxation times. The tumor masses of the malignant tumors were free of signals in the fat selective images, whereas in three out of six osteochondroma fat signals could be detected. Localized MR spectroscopy was more sensitive even to very low lipid content (lipid portion < 0.5%) in the tumors and revealed signals with J-coupling from seven out of 13 malignant tumors.

Adolescent↗