Information processing in nuclear magnetic resonance imaging.

An extended image analysis and classification system is presented to discuss the principal composition of the components as well as the methods of its realization in the field of reference based NMR diagnostics and tissue characterization.

[Results of nuclear magnetic resonance tomography studies in endocrine orbitopathy]. / Ergebnisse kernspintomographischer Untersuchungen bei endokriner Orbitopathie.

Magnetic resonance imaging (T1- and T2-weighted) was performed in 65 patients with Graves' disease. In addition, T2 relaxation times of each ocular muscle were measured. Of the muscles thus studied, 54.8% showed a thickening in coronary tomograms. An interaction between the optic nerve and the thickened ocular muscles at the apex of the orbit was suspected in 30.1%. It could not be confirmed that the thickening of the muscles and the T2 value were related. However, there was a high correlation between the rise in intraocular pressure and the T2 relaxation time. These results imply that the T2 relaxation time is extremely useful in interpreting the activity of Graves' disease and provide a diagnostic tool of prognostic value in monitoring and treating this disease.

Tissue characterization of benign brain tumors: use of NMR-tissue parameters.

To evaluate the potentials of NMR tissue parameters for tissue characterization we investigated 68 patients with benign brain tumors. Tissue parameters were accurately measured by a recently developed interlaced triple sequence. Each individual tumor was characterized by a set of three numbers (relaxation times T1 and T2 and proton density Rho). Different tumors exhibited significant overlaps of the three tissue parameters. Therefore a reliable prediction of the histological diagnosis based on the quantitative analysis of tissue parameters alone was not possible. T2-prolongation correlated well with water content and "regressive changes" in meningiomas and neuromas.

Magnetic resonance imaging of dysraphic myelodysplasia. Findings in 56 children and adolescents with postrepair meningomyelocele.

The spinal cord in 56 children and adolescents was examined by magnetic resonance imaging (MRI) many years after neonatal surgery on a meningomyelocele (average age 12 years). In a high percentage of cases, the diagnosis "tethered cord" was made. Associated anomalies were found with a frequency of 21%. Typical findings are presented and the impact of these results on therapy planning is discussed.

[Therapy of endemic goiter with levothyroxine and iodide. A multicenter study]. / Therapie der endemischen Struma mit Levothyroxin und Jodid. Ergebnisse einer multizentrischen Studie.

74 patients suffering from diffuse endemic goitre and with peripheric euthyrotic metabolism were treated for 6 months either with 150 micrograms levothyroxine (T4) daily (group I, n = 35), or with a combination of 100 micrograms levothyroxine and 130.8 micrograms potassium iodide (corresponding to 100 micrograms iodide) daily (group II, n = 39). This was followed in each case by a 3-month prophylactic administration of 100 micrograms iodide daily. After 3, 6 and 9 months the reduction of the goitre volumes--measured by sonography--was significantly different from the initial value in both groups. The reduction in goitre size was more marked in group II (-30.3%) than in group I (-25.2%), in each case after 6 months' treatment, but this difference was not significant. Suppression of the basal TSH levels in the serum coincided almost completely in both groups with an equidirectional increase after the subsequent iodide administration of 3 months' duration. Whereas in group I there was a renewed tendency towards thyroid enlargement under iodide prophylaxis, the diminution effect obtained in group II remained unchanged.

Errors in T1-determination using multislice technique and Gaussian slice profiles.

Multislice SE- or IR-sequences with different TR- and T1-times, respectively, are often used, to determine T1- and T2-values for tissue characterisation. To investigate the perturbating influence of the sequential excitation in multislice technique, we measured the signal intensities and calculated the T1-values of phantoms as a function of gap widths between neighboured slices. Phantoms contained fluids of different T1. We found a strong dependence of signal intensities and therefore of calculated T1-values on the gap width, when a T1/TR-ratio of more than 0.3-0.4 was reached. T1-values are considerably overestimated in this case, whereas T2-values are not influenced by the sequential excitation. We conclude that reliable T1-measurements necessitate a large spacing of more than 1 slice thickness between adjacent slices.

[Reference substance for initialling the marker space in NMR tomography]. / Referenzsubstanz zur Initialisierung des Merkmalsraumes in der NMR-Tomographie.

Dimethylsiloxane polymers are tested to serve as a reference medium in quantitative MR imaging. Simultaneously measured during the patient's examination, the reference data are used to normalize the intrinsic MR tissue parameters. This method helps to achieve interindividual comparability of tissue vectors which are defined by proton density, spin-spin and spin-lattice relaxation times, thus leading to a remarkable improvement in tissue classification.

MRI in cranial tuberculosis.

A case of multiple intracranial tuberculomas is presented. CT and MRI findings are discussed and compared. MRI showed multiple tuberculomas characterised by the same signal intensity as the surrounding brain parenchyma. Differentiation could be achieved only by the perifocal oedema of high signal intensity. Changes of the lesions during chemotherapy were monitored by CT and MRI and the results are presented.

[MR tomography of benign brain tumors]. / MR-Tomographie benigner Hirntumoren.

69 Patients with benign brain tumours were examined via MRI (30 meningiomas, 17 pituitary adenomas, 14 acoustic neuromas, and 8 craniopharyngiomas). Typical morphological characteristics and values of the MR tissue parameters (T1, T2, Rho) are presented. The combined analysis of tissue parameters and morphological details allows a satisfying differentiation between different pathohistological entities. Tumour capsule and displacement of neighbouring structures without signs of infiltrating growth are typical criteria of benign neoplasms.

[Potentialities of MR tomography in monitoring the therapy of malignant bone tumors]. / Möglichkeiten der MR-Tomographie in der Therapiekontrolle maligner Knochentumoren.

The value of MRI as a method for controlling treatment quantitatively was studied in four osteosarcomas and one Ewing sarcoma. Histologically proven change resulting from chemotherapy (2 patients) correlated with a significant increase in T2 of tumour tissue. In three other patients who did not respond to therapy, no change could be demonstrated. MRI appears to be valuable as a non-invasive method for monitoring treatment.

[MR tomography in glioblastomas and cerebral metastases]. / MR-Tomographie bei Glioblastomen und zerebralen Metastasen.

36 Patients with glioblastomas (17 cases) and cerebral metastases (19 cases) were investigated by MRI. The typical signal behavior at different acquisition parameters (T1-, T1/T2-, Rho- and Rho/T2-weighted) was analysed using an interlaced triple sequence. In most cases the NMR-tissue parameter T1, T2 and proton-density (Rho) were determined to evaluate the potentials for tissue characterisation. The results of unenhanced vs. enhanced scans (MRI plus Gd-DTPA, CT) were analysed.

[MRT in neurofibromatosis and tuberous sclerosis]. / MRT bei Neurofibromatose und tuberöser Sklerose.

The relatively rare neurocutaneous syndromes may produce neurological symptoms during childhood. After closure of the fontanelle, the radiological methods of choice are CT and MRT. The value of these two methods is demonstrated by twelve examples (eight neurofibromatoses, four tuberous scleroses). CT is superior to MRT in being able to show calcification; it is therefore the method of choice for tuberous sclerosis. On the other hand, MRT may show foci of neurofibromatosis; these can hardly be seen on CT. In order to show cerebral lesions in these two conditions, T2-weighted sequences are necessary.

[MR tomography in intracranial meningiomas]. / MR-Tomographie intrakranieller Meningeome.

The typical findings of intracranial meningiomas seen in 24 patients are described. The signal intensities at different acquisition parameters are analysed and optimal pulse sequences derived from these data. In 90% of the patients MR-tissue parameters were measured and correlated with the histological findings. Marked prolongation of T2-times was found in tumours showing regressive changes.