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.

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.

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.

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.

[NMR-tomography of cerebral midline tumors and cervical cord processes in children]. / NMR-Tomographie von zerebralen Mittellinientumoren und Halsmarkprozessen im Kindesalter.

Tumours of the brain, mesencephalon and cervical spinal cord in 10 children were examined by MRI. The most useful anatomical information was supplied by the sagittal midplane tomogram. Due to the prolongation of T2-times in brain tumours T2-weighted images were appropriate for detecting pathological structures even without space-occupying signs. Questions of operability and therapeutic effectiveness were reliably answered.

[Single photon emission computed tomography of patients with benign and malignant spinal diseases]. / Die Einzelphotonen-Emissions-Computertomographie (SPECT) bei Patienten mit benignen und malignen Erkrankungen der Wirbelsäule.

SPECT has been used in a comparative study with planar bone scintigraphy in 54 patients. Spatial resolution of the method is sufficient to localise the vertebral bodies, the spinous processes, the intervertebral, costotransverse and costovertebral joints. In all patients it was possible to relate the areas of increased uptake to specific anatomical sites of the spine known to be affected in the different conditions. A detailed localisation is rarely possible using planar scintigraphy alone, due to the complex osseous anatomy of the spine. In some patients lesions could be seen only with SPECT. SPECT is an invaluable supplement to planar scintigraphy of the spine.

[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.

[Use of long spin-echo sequences for imaging demyelinating diseases]. / Einsatz von langen Spinechosequenzen zur Darstellung demyelinisierender Erkrankungen.

A multiple spin-echo-sequence has been evaluated in diagnosis of demyelinating diseases. TE in these MR-experiments was between 14 and 336 msec, TR between 860 and 1660 msec. Three groups of patients were examined, and it could be shown that the probability to detect MS-plaques grows with long TE's up to 300 msec. T2-relaxation-time-values range between 126 and 250 msec. Different MS-plaques in the same patient might show different T2-values.

[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.

[The clinical value of sequential renal scans with 131 iodo-hipuran and renal perfusion with 99mtc compounds using computer analysis (author's transl)]. / Klinischer Wert der Nierensequenzszintigraphie mit 131Jod-Hippuran und der Nierenperfusion mit 99mTc-Präparaten nach Computerverarbeitung

Two methods of sequential scintigraphy are considered critically: a) Quantitative computer evaluation of nephrograms obtained by a gamma camera using 131Iodo-Hipuran. b) Quantitative flow studies of the kidneys after bolus injections of 99mTc preparations. Statistical evaluation of data from 171 patients examined by both methods has shown that the isotope nephrogram is not sufficiently sensitive for diagnostic purposes. Isotope nephrography combined with estimations of effective renal plasma flow on each side separately is of value to the urological surgeon by providing important information regarding severe degrees of renal functional impairment. Perfusion measurements, using a gamma camera and 99mTc preparations, are a promising survey method for the diagnosis of renal artery stenosis. (Much of this work is contained in a dissertation by C. Knick).

[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.

[Initial clinical results of tissue characterization by T1, T2 and proton density in nuclear magnetic resonance tomography]. / Erste klinische Ergebnisse der Gewebecharakterisierung durch T1, T2 und Protonendichte bei der Kernspintomographie.

The NMR parameters (proton density, relaxation times T1 and T2) have been assessed by Carr-Purcell-Meiboom-Gill (CPMG) spin echo sequences. A computer assisted analysis of the data of 21 patients with cerebral tumours allowed a classification of tumour tissue in different tumours. The use of quantitative procedures for tissue characterisation allows the differentiation of benign and malignant brain tissue by characteristic colour coding demonstrating morphological details like tumour, edema and necrosis as well as indicating the histological types of the tumours of the central nervous system.

Future of nuclear medicine--impact of new radiopharmaceuticals and of alternative methods such as nuclear magnetic resonance.

Nuclear medicine (NM) is returning to its origin by studying more and more metabolic signals using new positron or single photon emitting radiopharmaceuticals. Much of the success that has been achieved by PET is now being transferred to SPECT-techniques. In contrast to static planar scans the changing tissue concentration of radiotracers can now be quantified. In this respect radioimmunodetection using monoclonal antibodies has a tremendous future. It is quite probable that 99mTc will continue to be the principle radionuclide. Especially radiopharmaceuticals for "hot spot"-imaging will be important in the near future, for example radioactively labelled blood cells. NM has a unique contribution to offer to nuclear magnetic resonance (NMR) because of its emphasis on physiologic as well as anatomic imaging parameters. NM can interact with the new revolutionizing technology of NMR in two ways: NM can help to understand NMR and NMR can help to identify regions of interest to be studied by NM. For example, we cannot see metabolic processes of the brain in NMR which are seen by biological radiotracers such as dopamin receptors in NM. However, there is no doubt, that NMR will also have a negative impact on NM. The potential value of NMR for in vivo biochemical analysis seems to be tremendous. The additional information gained by NMR about metabolic processes may well change our entire understanding of health and disease. The advantage that NM procedures can be performed on an outpatient basis will apply to NMR as well. NM and NMR will be complementary modalities in the future.

The optimization of nuclear medicine procedures for the diagnosis and management of thyroid disorders in developing countries.

Thyroid disease is common in developing countries and its management is based on the measurement of thyroid function and the investigation of thyroid masses. This report discusses techniques and outlines a strategy for the measurement of thyroid function using radioimmunoassays of thyroid-related hormones in the blood. It makes proposals for the evaluation of thyroid morphology using echography, pertechnetate imaging and fine needle biopsy. Note is taken of the difficulties facing laboratories in developing countries and the International Atomic Energy Agency is concerned with the practical assessment of these recommendations and of any alternative proposals in this field.

Distribution pattern of radioactive labelled lipiodol-UF following intralymphatic application for therapy.

Endolymphatic radiotherapy with 4 mCi32P tri-n-octylphosphate and 1 mCi 131 I triolein LIPIODOL UF has been performed in 75 patients suffering from malignant melanoma of the lower extremity. On the average, 13.3% of the radioactive substance remains in the syringes and connecting tubes. In most patients the radioactive material available for therapeutic irradiation is further reduced due to contamination of operation sheets and swabs (mean: 15.3%). There is, however, still sufficient radioactivity remaining for effective internal irradiation of the lymph nodes. The average radiation dose absorbed by the lymphatic tissue is 90.998 rad. The method is limited by the hazard of radiation damage to the lungs. Almost 80% of these patients had detectable concentrations of radioactivity in the lung fields. The average radiation dose was found to be 299 rad. So far radiation induced fibrosis has bot been observed in this series.