[Diagnosis and staging of lunate necrosis. A current review]. / Diagnostik und Stadieneinteilung der Lunatumnekrose. Eine aktuelle Ubersicht.

Recently, early diagnosis and staging of Kienböck's disease was mainly influenced by imaging techniques (CT and MRI). New findings led to the staging classification of Lichtman and Ross (1994) which is recommended in the following. MRI allows diagnosis of the reversible bone marrow edema (stage I), which often is equivocal in conventional radiography. High-resolution CT facilities a more precise imaging of later stages in Kienböck's disease including spongiosal sclerosis (stage II), fractures at the proximal pole (stage III A), and initial osteoarthrosis (stage IV). For therapeutic considerations, contrast-enhanced MRI is extremely useful in stages II and III A, whereas MRI is redundant in stages III B and IV. Carpal instability (stage III B) is sufficiently visualized using conventional radiograms exposed in the neutral position. This review article reveals the value and indications of CT and MRI.

Imaging and staging of avascular osteonecroses at the wrist and hand.

Avascular ostenecroses (AVN) are unspecific focal sceletal lesions of vascular origin. At the wrist, AVNs are mainly seen in the lunate (Kienbock's disease) and the proximal scaphoid fragment in the presence of a nonunion disease (pseudarthrosis). Other types of osteonecroses are rare. The natural process of devitalization proceeds in steps: initially, there is a bone marrow oedema, followed by trabecula sclerosis, cystic transformation of the spongiosa, and bone fragmentation. End stages include carpal collapse (SLAC wrist) and osteoarthritis. For imaging of the sceletal morphology in AVN computed tomography is most useful, whereas initial stages and perfusion damages are better detected with contrast enhanced magnetic resonance imaging (MRI). In this paper a staging classification for Kienböck's disease and the scaphoid nonunion, considering the diagnostic and therapeutic consequences, is presented.

Fast spin-echo (FSE) and gradient- and spin-echo (GRASE) in fast MRI of the pelvis.

In this prospective study two different T2-weighted fast spin-echo (FSE) sequences and a gradient- and spin-echo (GRASE) sequence were compared in 20 consecutive patients undergoing clinical pelvic MR examinations. A GRASE and two FSE sequences were applied, whereby the FSE sequences differed from each other by altered echo spacings (15.0 and 22.5 ms) and T2 contrast. Quantitative image analysis included ROI evaluation of different S/N and C/N values. Visual image analysis was performed by two independent readers using a standardized score sheet for anatomic and pathologic findings. Overall image quality was significantly better in both FSE sequences. GRASE and FSE22.5 were superior in delineation of most of anatomic and pathologic structures due to intermediate to hypointense contrast behavior of pelvic fat compared to FSE15.0 in which fat was bright. Therefore, FSE15.0 was optimal for low intensity lesions. Short acquisition times of FSE and GRASE sequences allow application of two different techniques-fat hypointense respectively bright-for excellent lesion visualisation. This study demonstrates the usefulness of contrast manipulation in fast T2-weighted MRI techniques without special techniques, such as fat saturation.

True proton density and T2-weighted turbo spin-echo sequences for routine MRI of the brain.

Our aim was to evaluate the diagnostic reliability of turbo spin-echo (TSE) sequences compared to a conventional dual-echo spin-echo (SE) sequence in routine brain MRI at 1.0 T. The following demands were made on TSE sequences: acquisition time-reduction of at least 50% and true proton density (PD) contrast (low-signal cerebrospinal fluid). A conventional spin-echo and two single-echo TSE sequences were used in 150 patients, a dual-echo TSE sequence in addition in 50 patients. Demonstration of most anatomical structures and disorders was equivalent with TSE and SE sequences. Advantages of TSE were reduced flow artefacts on T2-weighted images, better lesion contrast on PD-weighted TSE images (especially in the dual-echo sequence) and acquisition time reduction to about 5 min (single-echo TSE) and 3:35 min (dual-echo TSE). Disadvantages of TSE were: reduced contrast of iron-containing substances such as haemosiderin and of areas of calcification. By virtue of the shorter acquisition time and diagnostic reliability dual-echo TSE proved the best sequence. If it is used with only one acquisition--whereby image quality but not diagnostic reliability is slightly decreased--acquisition time can be further reduced to 1:48 min. Application of a susceptibility-sensitive gradient-echo sequence, such as FLASH, compensates for the disadvantages mentioned above.

Delayed myelination in children with West syndrome: an MRI-study.

Eighteen children with West syndrome underwent MRI-examination of the brain. Five children were examined twice. Myelination of ten regions of the brain was retrospectively assessed on the MRI-examinations. The children could be divided in three groups of main diagnosis (cryptogenic West syndrome, tuberous sclerosis, pre-/perinatally acquired brain lesions). Delays in myelination were found in 17 out of a total of 23 examinations. In children with cryptogenic West syndrome and with tuberous sclerosis myelination was normal or only mildly delayed in the first month after onset of the spasms, but delays seemed to increase in the course of the West syndrome in these groups. In children with pre- or perinatally acquired brain lesions severe delays of myelination could be found already in the first weeks after the onset of the West syndrome. The assessment of myelination can therefore contribute to the diagnosis and understanding of the underlying disease in children with West syndrome.

Unilocular toxoplasmosis simulating intracerebral tumor.

Toxoplasmosis is a common infection with increased incidence in patients suffering from AIDS. In this paper we report a rare case of toxoplasmosis without evidence of AIDS: The patient had a singular tumor-like lesion in the right parietal lobe in CT and MRI. In neurosurgical intervention no tumor was found. Finally, different histopathological examinations led to the diagnosis of toxoplasmosis. Diagnostic and therapeutic regimes in patients with suspect tumor-like lesions should be discussed.

MRI assessment of myelination: an age standardization.

777 cerebral MRI examinations of children aged 3 days to 14 years were staged for myelination to establish an age standardization. Staging was performed using a system proposed in a previous paper, separately ranking 10 different regions of the brain. Interpretation of the results led to the identification of four clinical diagnoses that are frequently associated with delays in myelination: West syndrome, cerebral palsy, developmental retardation, and congenital anomalies. In addition, it was found that assessment of myelination in children with head injuries was not practical as alterations in MRI signal can simulate earlier stages of myelination. Age limits were therefore calculated from the case material after excluding all children with these conditions. When simplifications of the definition of the stages are applied, these age limits for the various stages of myelination of each of the 10 regions of the brain make the staging system applicable for routine assessment of myelination.

Myelination of the brain in MRI: a staging system.

In a retrospective study 516 cranial MRI examinations of children aged 1 month to 14 years were re-evaluated for myelination. An objective staging system for the assessment of the degree of myelination was designed, based on the characteristic patterns of myelin-typical signal which develop in the course of brain maturation. Thus myelination can be estimated using only routine MRI examinations; no additional measurements of signal intensities are necessary. In order to obtain detailed information, ten regions of the brain are ranked separately, with comparisons of the T1- and T2-weighted images for each region. The application of the staging system to the case material revealed typical age ranges for the stages, and retarded myelination in some children. In most cases the observed retardation affected several regions but never the whole brain. Such delays can only be detected by separate assessment of the degree of myelination in each region of the brain.

The value of spinal magnetic resonance imaging (MRI) in locating prolapses of lumbar intervertebral discs.

Between 1986 and 1988 100 patients in whom MRI had been used to diagnose prolapses of lumbar intervertebral discs were admitted to the neurosurgical department of the Munich Technical University. MRI proved to be a valuable diagnostic technique, even if one has to concede certain limitations to the usefulness of the results when compared to conventional methods, particularly in such cases where clinical symptoms are not clear. Typical findings are illustrated and compared with those seen in MRI, whose relative importance is discussed.

[Structures of the knee joint in nuclear magnetic resonance tomography. Improved representation with 3D volume imaging]. / Kniegelenksstrukturen in der Kernspintomographie. Verbesserte Darstellung durch das 3D-Volumen-Imaging.

Despite 3D gradient echo technique has a better spacial resolution than spin echo sequences, 3D imaging is not well accepted for clinical routine. Because of the large amount of data evaluation cannot be done by single photo-documented slices. Postprocessing of the 3D data sets with an image analysis system is indispensable. A maximum of two different gradient echo sequences (FLASH, FISP) are necessary for imaging of the whole interesting volume with continuous slices. Time of examination is shorter (16 resp. 32 minutes) compared with conventional spin echo sequences. In our opinion 3D gradient echo-sequences are a reliable noninvasive technique for the evaluation of pathological changes of the knee joint which could replace diagnostic arthroscopy in the future.

[Proton spin tomography in children and adolescents with so-called idiopathic scoliosis]. / Kernspintomographische Untersuchungen bei Kindern und Jugendlichen mit sogenannter idiopathischer Skoliose.

Somato-sensory evoked potentials (SSEP) were found to be pathological mostly in the lower extremities in 26 out of 45 children suffering from so called idiopathic scoliosis. We examined the vertebral spine and the spinal cord of 8 of them (with controlled SSEP-findings) by use of conventional MR-imaging and (where necessary) 3-dimensional-data-set following the Fournier-procedure. 6 of the 8 children showed alterations as follows: 1. A lipoma spreading partly extra-, partly intraspinally. 2. Subligamentous protrusions of the intervertebral disc (2 patients). 3. Dysraphic processes (2 patients). 4. An abnormally cranial ending myelon surrounded by a widened spinal channel. The findings are demonstrated and discussed concerning the questions whether the pathological SSEP and, furthermore, the deformity of the vertebral spine could be explained thereby. We are at least able to prove that some of the children with so called idiopathic scoliosis show pathological evoked potentials and MRI-findings.