Brain dysfunction during motor activation and corpus callosum alterations in schizophrenia measured by cerebral blood flow and magnetic resonance imaging.

Sixteen unmedicated (14 never-medicated, 2 with washout periods of 1-2 weeks) schizophrenic patients displaying positive symptoms (e.g., formal thought disorder, hallucinations, delusions) without negative symptoms (e.g., flattening of affect, loss of energy, anhedonia--type I patients), 15 unmedicated (with washout periods from 1 week to 2 years) patients with marked negative symptomatology [type II patients; criterion score below 15/above 35 on the Munich version of the Scale of Assessment of Negative Symptoms (SANS), respectively], and 31 matched normal controls were investigated using regional cerebral blood flow [rCBF; dynamic single-photon emission computerized tomography (SPECT) with Xenon-133 as tracer] and magnetic resonance imaging (MRI; spin-echo technique, T1 weighted, midsagittal cuts). rCBF measurements were performed during both resting conditions and simple motor activation. Separately, on the same day, we performed a planimetric evaluation of the callosal-brain ratio in all subjects using MRI. In accordance with previous results on a smaller sample, we found signs of diffuse bilateral rCBF hyperactivation in type I patients, as compared with signs of nonreactivity in type II schizophrenics. Both activation patterns were different from a strictly contralateral sensorimotor rCBF activation seen in normal persons (only 8 studied with SPECT). The planimetry of relative callosal area did not reveal differences compared to normal persons, when type I/II patients were taken together. However, the threefold increased variance as compared with that found in normal persons suggested biological heterogeneity in patients. We found an increase of relative callosal size in type I as compared with type II patients. In the light of some recent findings linking lack of laterality of several brain functions to increased callosal size, we propose lack of laterality/diffuse hyperactivation and increased callosal size to be connected with positive symptomatology/good prognosis schizophrenia, and vice versa.

Disk processes in MR.

Disk processes can be differentiated in MR with the introduction of high resolution coils and the use of a multi slice technique with a minimal slice thickness of 5 mm. By using a sensitive double echo sequence we found that in the 80 patients examined the size and extent of the posterior herniation could be well demonstrated. Sagittal slices show the relationship of the herniation to the spinal cord. The pathomechanical parts of a disk process such as ruptured or preserved anulus fibrosus, perforated or intact posterior longitudinal ligament can be differentiated. For lateral lying processes in connection with the foramen intervertebral and the spinal roots an axial slice parallel to the intervertebral space is recommended. All CT findings especially in the cervical spine region were shown and further qualified.

Gas-sensing internal enzyme fiber optic biosensor for hydrogen peroxide.

Feasibility is demonstrated for a novel gas-sensing, internal enzyme biosensing scheme for the selective measurement of hydrogen peroxide. Two horseradish peroxidase catalysed reactions are evaluated for the detection of hydrogen peroxide as it crosses a microporous Teflon membrane at 37 degrees C. The rate at which hydrogen peroxide crosses the membrane is determined by either a fluorescence or chemiluminescence measurement and this rate is related to the concentration of hydrogen peroxide in the sample solution. Detection limits of 0.7 mM and 10 muM are estimated for the fluorescence and chemiluminescence methods, respectively. Selectivity is demonstrated for hydrogen peroxide over ascorbic acid, uric acid and tyrosine.

[Nuclear magnetic resonance tomography of the spine]. / Kernspintomographie der Wirbelsäule.

The present paper deals with the results of 48 MR examinations of known spinal abnormalities. The use of a method strictly related to the individual problem helps to reduce the duration of the examination. Sagittal cuts are particularly useful for demonstrating much of the spinal canal. The spin-echo method is used for all examinations. Demonstration of the cord was performed by using short repetition and echo times (TR, TE). For showing the outer margin of the spinal canal, longer TR and TE should be selected. Surface coils are important for demonstrating spinal disease, since the larger images can be performed without increasing the duration of the examination.

[Magnetic resonance imaging of the wrist--comparison of high resolution pulse sequences and different fat signal suppression techniques in cadavers]. / Magnetresonanztomographie des Handgelenkes--Vergleich hochauflösender Pulssequenzen und unterschiedlicher Fettsignalunterdrückungen an Leichenpräparaten.

PURPOSE: To evaluate high resolution sequences with and without fat-suppression techniques for MR imaging of the wrist. MATERIALS AND METHODS: 10 cadaver wrist specimens were imaged with 12 MR sequences (SE: 400 ms/20 ms, TSE: 3000 ms/119 ms/17 ms, fatsat (FS) TSE: 3000 ms/17 ms and 3000 ms/45 ms, STIR: 2619 ms/29 ms/160 ms, DESS 3D: 43.7 ms/9 ms/35 degrees FS and 25.4 ms/9 ms/35 degrees water excitation (WE), CISS 3D: 12.2 ms/5.9 ms/40 degrees and FLASH-sequences: 53 ms/11 ms/40 degrees FS, 23 ms/11 ms/40 degrees WE and 45 ms/11 ms/30 degrees FS) at 1.5 T. Slice thickness was 3 mm, FOV 80 x 70 mm (pixel size 0.31 x 0.31 mm). Signal intensity was measured by an ROI in bone marrow, fluid, hyaline cartilage, scapholunate (SL) ligament and triangular fibrocartilage and S/N- and C/N-ratios were calculated. Additionally, a visual evaluation was performed. RESULTS: The highest homogeneity and the least artifacts were achieved by the T1-w SE sequence. For the STIR and PD-FS TSE sequence high rankings were found for the detection of free water. The PD FS sequence had high ranking also for visualization of the SL ligament and the triangular fibrocartilage. The best sequence for the assessment of hyaline cartilage was the FLASH-FS sequence. For detailed analysis of bony structures the CISS sequence performed best. CONCLUSION: The isolated use of a PD-FS-TSE sequence enables for evaluation of all clinically relevant structures at the wrist. Dedicated questions for hyaline cartilage are answered best by the use of a FLASH 3D-FS sequence. Selective water excitation reduces acquisition time to 60%, nevertheless FS sequences are still diagnostically superior to WE sequences.

[Magnetic resonance tomography of the postoperative lumbar spine. A comparison of the MR versus CT images in recurrent intervertebral disk prolapse]. / Kernspintomographie der operierten Lendenwirbelsäule. Bildvergleich MR versus CT bei Bandscheibenrezidiven.

In the present study, 40 patients who had undergone disc surgery were examined by high resolution CT and MR for possible recurrence of the disc prolapse and the results are compared. It appears that high resolution spinal MR, using its various tissue parameters provides no new insights into possible recurrence of a disc prolapse. As is the case with CT, the investigator must also evaluate other morphological and clinical factors. In spite of this, MR can be useful in the investigation of abnormal spines.

[Duration of the retention of iodine contrast agents in the body--an x-ray fluorescence analytical determination]. / Verweildauer von Jodkontrastmittel im Körper--röntgenfluoreszenzanalytische Bestimmung.

X-ray fluorescence is able to detect iodine as it is used in contrast agents with low concentrations in vivo in man. Measurements of the time dependence of this concentration after angiographies show that one must distinguish between patients with a defect in the blood-brain barrier and those with an angiographically demonstrated arterial flow reduction.

Clinical evaluation of further-developed MRCP sequences in comparison with standard MRCP sequences.

The purpose of this study was the comparison of technically improved single-shot magnetic resonance cholangiopancreatography (MRCP) sequences with standard single-shot rapid acquisition with relaxation enhancement (RARE) and half-Fourier acquired single-shot turbo spin-echo (HASTE) sequences in evaluating the normal and abnormal biliary duct system. The bile duct system of 45 patients was prospectively investigated on a 1.5-T MRI system. The investigation was performed with RARE and HASTE MR cholangiography sequences with standard and high spatial resolutions, and with a delayed-echo half-Fourier RARE (HASTE) sequence. Findings of the improved MRCP sequences were compared with the standard MRCP sequences. The level of confidence in assessing the diagnosis was divided into five groups. The Wilcoxon signed-rank test at a level of p<0.05 was applied. In 15 patients no pathology was found. The MRCP showed stenoses of the bile duct system in 10 patients and choledocholithiasis and cholecystolithiasis in 16 patients. In 12 patients a dilatation of the bile duct system was found. Comparison of the low- and high spatial resolution sequences and the short and long TE times of the half-Fourier RARE (HASTE) sequence revealed no statistically significant differences regarding accuracy of the examination. The diagnostic confidence level in assessing normal or pathological findings for the high-resolution RARE and half-Fourier RARE (HASTE) was significantly better than for the standard sequences. For the delayed-echo half-Fourier RARE (HASTE) sequence no statistically significant difference was seen. The high-resolution RARE and half-Fourier RARE (HASTE) sequences had a higher confidence level, but there was no significant difference in diagnosis in terms of detection and assessment of pathological changes in the biliary duct system compared with standard sequences.

[Comparative studies of cerebral blood flow measurements and measurements of the size of the corpus callosum in patients with schizophrenia]. / Vergleichende Untersuchungen von Hirndurchblutungsmessungen und Messungen der Grösse des Corpus callosum an Schizophren-Kranken.

In this study healthy subjects and schizophrenic patients of the so-called Type I and Type II subgroups were examined in each case with a morphological method to determine the size of the corpus callosum and with a method to measure a physiological functional parameter, namely, the regional cerebral blood flow (rCBF). MR and dynamic single photon emission CT were used (in our case as differential method). The study reveals for the first time classified into subgroups of the disease, scientifically measured differences both in the size of the corpus callosum and in the distribution pattern of the blood flow. Whereas the patients of type I had an enlarged corpus callosum and increased blood flow during the task with which they were confronted, these organs were mainly smaller in size with type II patients without an increase in the global blood flow during the relevant task. The statistical data--averaged over patient groups--show these differences clearly, but due to biological scatter it has so far not been possible to arrive at a diagnosis in individual cases.

Signal changes in liver and spleen after Endorem administration in patients with and without liver cirrhosis.

The goal of this study was compare the effect of Endorem on the signal intensity of the spleen in patients with normal liver tissue and in patients with liver cirrhosis. Thirty patients with normal liver tissue and 47 with liver cirrhosis were examined before and after i.v. Endorem administration. The patients were examined with a 1.5-T magnet system (Magnetom Vision) using a semiflexible cp-array coil. Three different pulse sequences were used: a T1-weighted gradient-echo sequence, a T2-weighted fast spin-echo sequence with spectral fat suppression, and a T2*-weighted gradient-echo sequence. The signal-to-noise ratios (SNRs) of two areas of the liver and spleen were determined. The mean SNRs of the liver and spleen in patients with and without liver cirrhosis were compared. For assessment of statistical significance, the t-test at a level of P < 0.05 was applied. After i.v. administration of Endorem, no differences were seen with the T1-weighted gradient-echo sequence for the liver and spleen and, with the T2-weighted fast spin-echo sequence, no differences were found for the spleen. Significant differences between both groups were seen for the liver with the T2-weighted fast spin-echo sequence. The SNR in the noncirrhotic liver group was 57.4% lower than the SNR in the cirrhotic liver group. With the T2*-weighted gradient-echo sequence, the SNRs of the liver and spleen in the noncirrhotic liver group, compared with the cirrhotic liver group, were 126.8% and 45.6% less, respectively. The effect of Endorem on the liver in patients with Child C-stage liver cirrhosis was 32.1% less than in patients with Child B-stage liver cirrhosis. Likewise, the Endorem effect on the spleen was 27.1% less in patients with Child C-stage compared with Child B-stage liver cirrhosis. Hepatic and splenic uptake of Endorem is significantly decreased in patients with liver cirrhosis.

Effect of superparamagnetic iron oxide on bone marrow.

The goal of this study was to compare the effects of SPIO particles on the signal intensity of the bone marrow of the vertebra spine in patients with and without liver cirrhosis. Forty-eight patients with normal liver tissue and 56 patients with liver cirrhosis were examined before and after intravenous SPIO administration, using a 1.5-T system (Magnetom Vision, Siemens, Erlangen, Germany) with a semiflexible cp-array coil. Three different pulse sequences were applied: a T1-weighted gradient-echo sequence, a T2-weighted fast spin-echo sequence with spectral fat suppression and a T2*-weighted gradient-echo sequence. The signal-to-noise ratio (SNR) of the liver, vertebra bone and paraspinal muscle were obtained. The SNR value change in each patient group and the SNR value difference between the two groups were evaluated. For assessment of statistical significance, Student's t-test with a level of p < 0.05 was applied. No significant differences in the SNR values of the liver and bone marrow between the two groups could be seen with any of the three sequences precontrast. Using the T1-weighted gradient-echo sequence in the noncirrhotic liver group, pre- and postcontrast comparisons of the SNR values of the liver and bone marrow indicated a decrease of approximately -44.3% (p = 0.02) and increase of approximately 15.3% (p = 0.04), respectively. No significant change was seen in the cirrhotic liver group. With the T2-weighted fast spin-echo sequence, a significant decrease of the SNR value of the liver and the bone marrow in both groups was seen. With the T2*-weighted gradient-echo sequence, the signal intensity decrease of the normal liver tissue was approximately -65.6% (p = 0.00), in cirrhotic liver tissue the decrease was -29.9% (p = 0.02). The SNR values of the bone marrow showed a decrease of -27.8% (p = 0.04) in the noncirrhotic liver group, whereas in the cirrhotic liver group it was only -11.3% and statistically not significant. The effect of SPIO particles on the liver and bone marrow is significantly less in patients with liver cirrhosis.

[New techniques and pulse sequences in MRI of the liver]. / Neue Techniken und Pulssequenzen bei der MRT der Leber.

PURPOSE: The MRI techniques which have contributed to increasing utilization of MRI for abdominal imaging are described and recent advances addressed. METHODS: For breath-hold examinations of the abdomen, two basic techniques are required: array coil technology and fast and ultrafast pulse sequences providing T1 and T2 contrast. RESULTS: Circular polarized array coils render high signal-to-noise ratios (SNR) within large imaging volumes. With fast gradient-echo sequences the liver can be scanned with or without fat saturation within one breath-hold. When adequate parameters are selected, T2-weighted fast (turbo) spin-echo sequences allow high contrast between normal liver tissue and focal liver lesions, even if breath-hold acquisition is applied. Moreover, good soft tissue contrast can also be achieved with ultrafast single-shot sequences. Based on this sequence type, MRCP with a 512 matrix could be performed. The "TRUE FISP" allows for high resolution visualisation of vessels without contrast media. Three-dimensional T1-weighted sequences allow for scanning the upper abdomen with a slice thickness of 3 mm within one breath-hold. Diffusion-weighted sequences contribute to the characterisation of focal liver lesions. DISCUSSION: Modern MRI technology including phase-array coils and high-performance gradient systems made it possible to perform all examinations in breath-hold techniques, reducing motion artifacts.

[MR imaging of the cervical spine using special coils]. / MR-Darstellung der HWS mit Hilfe von Sonderspulen.

The signal/noise ratio of MR images can be improved for organs near the surface by means of special coils. It is shown for neck imaging that a close-fitting saddle-shaped coil is more suitable for application between C 2 and Th 1, than a saddle coil for the entire head or a disc-shaped coil. Such a close-fitting saddle-shaped coil is an essential prerequisite for effective neuroradiological diagnoses of the spinal cord with nerve roots, of the spinal column, and of the vessels of the neck.