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.

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.

MRI-assisted radiation therapy planning of brain tumors--clinical experiences in 17 patients.

A new and simple method for precise determination of lateral opposed treatment portals was developed and used in 17 patients. Compared to CT, MRI led to significant changes of portals in 59% (10/17) of cases. Individual shielding blocks could be precisely designed by use of our new method. MRI is the procedure of choice in local radiation therapy planning of brain tumors.

NMR follow-up studies of CNS-tumors in infancy and childhood.

Sixteen children with brain tumors, fifteen of which were located in the posterior cranial fossa, were followed-up postoperatively with NMR. Four recurrences of medulloblastoma and one recurrence of an ependymoma were found. Three children showed signs of known therapeutic sequelae such as hygroma, atrophy and dilatation of the subarachnoid space. Previously unreported, boundary layer lesions were found in 8 children. The etiology of these lesions and their differentiation from tumor recurrence are discussed.

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.

Bone grafting in total hip replacement. Preliminary results with MRI.

MRI of ten hip joints in nine patients with total hip replacement and reconstruction of the acetabulum with autologous bone grafts, were reviewed. The viability of inserted bone grafts was clearly documented by MRI. Characteristic differences in signal intensity between autologous and homologous bone grafts are discussed. Despite extended metallic artifacts in the operated region, sufficient diagnostic information was available in most cases. No side effects were reported.

[Tissue characterization with T1, T2 and proton density: dream and reality]. / Gewebecharakterisierung mit T1, T2 und Protonendichte: Traum und Wirklichkeit.

A survey of the measurement values T1 and T2 based on radiological studies of the last two years shows a high degree of variation in these measurement values with regard to normal and pathological tissues of different organs and regions of the body. T1, which is dependent on field strength, is not suitable for interinstitutional comparison. At present the methods used for T2 measurements are so different from one another that the potential comparability of T2 cannot be realised. The combinations of T1 and T2--as presented in various radiological studies -show signs of tissue characterisation. The expected high degree of selectivity caused by using different measurement methods has not yet been confirmed. The measurement of T1 and T2 in lesions under drug and radiotherapeutic treatment seems to be informative in respect of prognosis.

[Endoscopic retrograde ileography (ERI). A contribution to the endoscopic-radiological investigation of the ileocecal region]. / Endoskopisch-retrograde Ileographie (ERI). Ein Beitrag zur endoskopisch-radiologischen Diagnostik der Ileozökalregion.

Following high colonoscopy, a catheter was introduced into the caecum in 16 patients and contrast material and air were injected. In ten patients it proved possible to obtain selective double contrast demonstration of the terminal ileum and, in two patients, a single contrast examination was obtained. In four patients there was no reflux, but two of these had severe and extensive stenoses of the terminal ileum.

[Transient osteoporosis or femur head necrosis? Early diagnosis using MRT]. / Transitorische Osteoporose oder Femurkopfnekrose? Frühdiagnose mit der MRT.

Transient osteoporosis of the hip is a syndrome that does not seem to be widely known; this is also true for its radiological appearance. It is often mistaken for avascular necrosis of the femoral head, metastatic or inflammatory disease. These differential diagnoses lead to more or less invasive procedures, although transient osteoporosis does not require more than immobilisation for complete remission. MRI was done in 38 patients with acute hip pain, 13 had femoral head necrosis and 8 transient osteoporosis. Follow-up studies via MRI in patients with transient osteoporosis revealed 3 stages (diffuse, focal, residual) during the clinical course of which stage II is similar to femoral head necrosis but always without the typical sclerotic rim.

[NMR studies of the central nervous system in pediatrics]. / NMR-Untersuchungen des zentralen Nervensystems in der Pädiatrie.

The central nervous system in 70 infants, children and adolescents has been examined by NMR. Phase I of the continuing investigation dealt with the applicability and scope in this group of patients. A retrospective comparison with CT was used to examine the possibility of enhancing and differentiating various tissues. The results have shown that NMR can extend the diagnostic possibilities beyond those of CT in the paediatric age group.

[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.

[Intracranial tumor-like lesions in children and young adults with multiple sclerosis]. / Intrakranielle tumorähnliche Läsionen bei Kindern und jungen Erwachsenen mit multipler Sklerose.

Atypical early manifestations of multiple sclerosis (MS) are common in children and young adults. 6 patients (aged 5 to 33 years) were examined by MR because of confusing neurological manifestations. In addition to small MS lesions there were also large intracerebral lesions which, however, did not occupy additional space but which looked more like tumours or abscesses. The lesions were sharply demarcated cystic formations with margins that enhanced with contrast. The diagnosis of these lesions presents difficulties, the differential diagnosis including MS and its variants, neoplastic, infectious and vascular processes. MR can provide valuable diagnostic information.

[MR tomography in tumors of the posterior cranial fossa in childhood]. / MR-Tomographie bei Tumoren der hinteren Schädelgrube im Kindesalter.

MR tomography was performed on 23 children with tumors in the posterior fossa. In 14 cases, the MR tissue parameters were determined. Astrocytomas can be easily differentiated from medulloblastomas and ependymomas on the basis of their localization and signal intensities. Grading of astrocytomas and distinction between medulloblastomas and ependymomas was not possible. Because of high tissue contrast, multiplanar imaging and minimal artifacts, MR proved to be the method of choice for planning surgery and for the follow-up of tumours in the posterior fossa.

[MR tomography of thoracic and abdominal tumors in childhood and adolescence]. / MR-Tomographie thorakaler und abdominaler Tumoren im Kindes- und Jugendalter.

MRI was performed on 25 infants, children and adolescents with thoracic and abdominal tumours. The specific contribution of MRI to diagnosis, treatment planning and therapy monitoring is demonstrated. In some cases the T1 and T2 relaxation times were determined; this may clarify the different signal intensities of tumour and neighbouring organs and contribute to differentiation between Wilm's tumour and neuroblastoma.

[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.

[Definitions of pulse sequences and parameter weightings in the NMR tomogram]. / Definitionen von Pulssequenzen und Parametergewichtungen im NMR-Tomogramm.

Due to the different possibilities of image creation in MR tomography there is no clear terminology of pulse sequences and MR images. This paper tries to define the designation of pulse sequence parameters in a practical way and to specify the term "parameter weighting of MR images". Starting with general definitions, special definitions for CNS and liver are elaborated.

[31-phosphorus spectroscopy of osteogenic sarcoma. Possibilities in therapy control in comparison with imaging methods]. / 31Phosphorspektroskopie bei osteogenem Sarkom. Möglichkeiten der Therapiekontrolle im Vergleich mit bildgebenden Verfahren.

31-phosphorus spectroscopy was used to control the results of chemotherapy in a patient with an osteogenic sarcoma. The findings were compared with conventional imaging methods (DSA, MRT and conventional radiography). The imaging methods do not provide reliable information regarding growth of tumour tissue during treatment, whereas the determination of phosphate concentration in the tumour provides direct information concerning tumour metabolism.

[MR tomography of astrocytic tumors (I-III)]. / MR-Tomographie astrozytärer Tumoren (I-III).

Magnetic resonance (MR) imaging was performed on 37 patients with histologically confirmed astrocytomas (I-III). In addition, the MR tissue parameters T1, T2 and proton density (RHO) were analysed by an interlaced CPMG spin echo sequence. Characteristic morphologic tumour patterns which subdivide astrocytomas into each different tumour grade are presented. Quantitative analysis of MR tissue parameters provides a statistically proven classification of each tumour grade and allows differentiation between "semibenign" astrocytomas (II) and "relatively malignant" astrocytomas (III), with high accuracy.

[Gadolinium dimeglumine gadopentetate compared to CPMG sequencing and image synthesis]. / Gadolinium-Dimeglumin-Gadopentetat im Vergleich mit der CPMG-Sequenz und der Bildsynthese.

The skulls of 46 patients were examined by means of ordinary scans and after contrast. 24 of these patients with cerebral abnormalities had scans, using identical planes, with and without contrast and with CPMG sequences. Contrast in intracranial, but extracerebral (extra-axial), tumours (meningiomas, neurinomas) was much better after using contrast, but intracerebral (intra-axial) tumours were mostly shown as well on T2-rated CPMG sequences. Image synthesis has shown that contrast uptake occurred only in solid tumour regions.