We acquired high-resolution MRI and anisotropically diffusion-weighted images (DWI) with direction-selective gradients of the brain stem in 20 healthy volunteers, to identify brain-stem structures such as white-matter tracts and nuclei which show diffusion anisotropy. After averaging and superposition of individual cuts, the images were projected onto appropriate plates of the Schaltenbrand and Wahren anatomical atlas. We identified 20 structures – white-matter tracts and some nuclei – with high contrast. The direction of fibres could be determined as areas of increased (parallel to) or decreased diffusion (perpendicular to the gradient). This study may contribute to understanding of the functional anatomy of the brain stem.

Objective. To provide data on the normal distribution of cartilage thickness in the knee joints of old-aged individuals. Design. The accuracy and reproducibility of cartilage thickness measurements were evaluated with A-mode ultrasound, and the cartilage thickness distribution was examined throughout both knee joints of nine individuals aged between 62 and 94 yr. Background. Data on the variation of cartilage thickness in the joint surfaces are relevant for the design of computer models of diathrodial joints and for surgical and arthroscopic procedures, particularly the calculation of cartilage material properties from indentation tests. Methods. A 12.5 MHz A-mode ultrasound transducer was used, and after determining the accuracy and reproducibility of the system in comparison with CT arthrography and anatomical sections, the cartilage thickness was measured throughout the knee at 256 coordinate points. Results. A-mode ultrasound yields results consistent with established methods. The cartilage thickness is distributed regularly in the knee-joint of older individuals. However, the absolute values are considerably lower than those previously reported for younger people, the mean (and maximal) thickness being 2.0 mm (3.3 mm) in the patella, 1.9 mm (3.3 mm) in the femur, and 1.9 mm (3.5 mm) in the tibia. Conclusion. If the results of computer models or surgical strategies are to be applied to the demographically important group of older individuals, the typical distribution of articular cartilage thickness in this group should be taken into consideration.

A fast, reproducible, and noninvasive method is required for quantifying cartilage thickness clinically and for studying the deformation of articular cartilage during and after mechanical loading in vivo. The objective of the current investigation was to test the repeatability of regional distribution patterns of patellar cartilage thickness in the living on the basis of a fat-suppressed magnetic resonance imaging sequence with a short acquisition time and three-dimensional digital data processing. The knees of eight healthy volunteers were transversally imaged with a fat-suppressed FLASH-3D (fast low angle shot) sequence (acquisition time: 4 minutes and 10 seconds). In each case, the joint was newly positioned before each of the six replicate measurements was taken. The patellar cartilage was reconstructed three-dimensionally, and the distribution of cartilage thickness was determined with a three-dimensional minimal-distance algorithm. Whereas the cartilage volume ranged from 3,198 to 7,149 mm3, the mean coefficient of variation for the 6-fold volume measurement was 1.35%. On average, 75.1% (+/- 4.1%) of all test pixels could be attributed to the same cartilage thickness interval (0.5 mm) by image analysis; 14.8% (+/- 2.4%) deviated by one interval; 6.6% (+/- 1.5%), by two intervals; and 3.5% (+/- 1.8%), by more than two intervals. We conclude that, on the basis of a magnetic resonance imaging sequence with an acquisition time of less than 5 minutes, the quantitative distribution of cartilage thickness can be determined with high precision in vivo.

Data on articular cartilage thickness in the living are important for the design for computer models, aimed at preoperatively assessing the effect of surgical procedures on joint contact and load transmission, and for the calculation of cartilage material properties from its deformational behavior as determined during arthroscopy. A non-invasive method for measuring cartilage thickness in living subjects is, however, not available. A technique based on magnetic resonance imaging has therefore been tested for assessing articular cartilage thickness throughout joint surfaces. The accuracy is determined by comparing cartilage thickness maps obtained from three patellar specimens with a fat-suppressed three-dimensional gradient-echo sequence (resolution 2 x 0.31 x 0.31 mm) to those obtained with CT arthrography, A-mode ultrasound and anatomical sections. The distribution patterns are quantitatively compared using image analysis. The highest agreement was obtained for MRI and the sections (50% identical pixels), but all techniques yielded very similar results. On average, MR slightly underestimated the cartilage thickness compared with CT and the sections, and overestimated it compared with ultrasound. No evidence of differences in the degree of similarity could be detected in areas of thin and thick cartilage. We conclude that, if the resolution and accuracy of the method presented are considered acceptable, MRI is available for repeatable determination of topographical maps of articular cartilage thickness in living subjects. These data can be used to determine joint contact and stress in computer models and to calculate cartilage material properties in vivo.

Using a recently developed image analysis method to quantify the time course of chromatolysis in injured motorneurons we tested the effect of the calcium entry blocker nimodipine (1000 ppm in food pellets) on regenerating and degenerating motoneurons. Following facial-facial, hypoglossal-hypoglossal anastomosis with complete regeneration and following facial and hypoglossal nerve resection which causes a partial neuronal degeneration and postoperative survival times of 4 to 112 days, the texture of the Nissl substance of facial and hypoglossal motoneurons was analyzed on both sides of the brainstem in paraffin serial sections with a VIDASplus image analyzer. Monitoring alterations of the Nissl substance in 252 Wistar rats we measured an effect of nimodipine in the cytoplasm of the injured neurons: nimodipine attenuated the chromatolytic reaction in regenerating and degenerating motoneuron pools in comparison to placebo treatment. These data are consistent to previous findings that nimodipine has profound neuroprotective effects.

A method for the assessment of articular cartilage thickness based on MRI is presented and tts accuracy and reproducibil‐tty tested. Six specimens of human patellae were imaged, using a fat‐supressed FLASH 3D sequence, and sectioned with a high‐precision band saw. The reglonal dlstribution of articular cartilage thickness was determined from the MR images and from the anatomical sections (intervals of 0.5 mm). Wtth image analysis 50–90% of the image points were found to lie within exactly the same thickness interval in corresponding patterns, and tess than 17% deviated more than 0.5 mm. More than 85% of ali pixels were reproducible wtth MRI after new positioning of the Joint No influence of the read‐out direction and no important differences between areas of thin and thick cartilage could be detected. The authors conclude that MR chondro‐crassometry can provide accurate and reproducible Information on cartilage thickness.

The objective of this article was to analyze the accuracy and precision with which the quantitative distribution of articular cartilage can be determined in the knee joint using MRI. A three-dimensional (3D) technique that accounts for the out-of-plane deviation of the interface normal in strongly curved joint surfaces (3D MR-CCM) has been developed for cartilage thickness measurements. Eight cadaveric knee-joint specimens and six volunteers were imaged using a fat-suppressed gradient-echo sequence at a resolution of 2 x 0.31 x 0.31 mm(3). Cartilage volumes and topographical thickness maps were obtained and compared with those derived from anatomical sections by image analysis. The deviation of the MR volumes from those of the sections was 1-12%, the coefficient of variation after repositioning ranged from 2.9% (patella) to 8.2% (lateral tibial plateau). Between 60% and 80% of all image points could be attributed to identical thickness intervals, less than 20% deviating by more than 0.5 mm. The intraobserver and interobserver reproducibilities were very high in both the specimens and the volunteers. In the knee joint, 3D reconstructions of the cartilages, and measurements that take into account the out-of-plane deviation of the interface normals (3D MR-CCM), are required.

Objective. The objective of this study was to analyse the potential of magnetic resonance imaging for valid determination of patellar cartilage thickness, comparing currently available pulse sequences. Design. In six patients and one cadaver the cartilage was repetitively imaged employing three spin-echo and six three-dimensional gradient-echo sequences. In the cadaveric specimen the total volume and the regional distribution of cartilage thickness were assessed and compared with the values obtained from anatomical sections by image analysis. Results and conclusions. The FLASH and fat-suppressed FLASH sequences allowed the most accurate determination of the cartilage volume and thickness. Fat-suppression considerably increased the contrast of the cartilage to the synovial fluid, fat and bone marrow, yielding higher reproducibility of the volumetric measurements. The remaining difference from the anatomical volume and thickness may be because the calcified cartilage is not delineated by magnetic resonance imaging.

BACKGROUND:Previous studies have shown that the trochlear notch is deeper than necessary for an exact fit with the humerus. However, humero-ulnar joint space width and contact areas have so far not been quantified for variations in the load and angle of flexion.METHODS:Six fresh cadaveric specimens were investigated at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion and at loads of 25 and 500 N, simulating resisted elbow extension. The joint space width and contact were determined, using polyether casting material.RESULTS:At 25 N all joints made contact in the ventral and dorsal aspects of the articular surfaces, whereas in the depth of the trochlear notch the joint space was on average between 0.3 and 2.8 mm wide, with some variation between individuals. At 500 N the joint space width was considerably reduced and the contract areas expanded towards the depth of the notch. The size of the dorsal contact areas was significantly smaller at 30 degrees and that of the ventral ones at 120 degrees, their ventro-dorsal ratio decreasing considerably from 30 degrees to 120 degrees (p < 0.01).CONCLUSION:These results indicate that the size of the contact areas depends to a slight extent on the joint position, but that at all loads and flexion angles a bicentric contact and an important central joint space width emerge because of the concave incongruity of the joint. These data may be used for numerical calculations, analysing the effects of incongruity on the joint stress and on the functional adaptation of the subarticular tissues.

The thickness of patellar articular cartilage was assessed in a cadaveric human knee joint by magnetic resonance imaging. Imaging was conducted at 1.0 T, using three-dimensional gradient-echo sequences. From each of the sequences the total cartilage volume, the size of the articular surface, the mean cartilage thickness and the regional distribution of cartilage thickness were determined by image analysis. These values were then compared with those obtained from anatomical sections. The fat-suppressed flash sequence was found to allow the most accurate evaluation of the total volume and the regional distribution of the articular cartilage. Slight underestimation of the cartilage thickness by about 5% may be due to the fact that the calcified layer is not made visible by magnetic resonance imaging. There is, however, a very high degree of similarity between the distribution patterns obtained from the MR images and the anatomical sections. The contrast-to-noise ratios and reproducibility were also highest with the fat-suppressed flash sequence. This pulse sequence can therefore be recommended for experimental and clinical use.

A new and technically simple Romanowsky-Giemsa (RG) stain is proposed as a standardized technique for use in histology. An RG stock solution (pure azure B 7.5 g/l, eosin Y as eosinic acid 1.2 g/l in dimethylsulfoxide) is diluted to form the working solution with HEPES-buffer, pH 6. Staining time is 30-90 min after formol-calcium solution (or 2-4 hr after formaldehyde-organic acid mixtures). The resulting overstained sections are to be differentiated. A tannic acid-acetic acid combination in an isopropanol-water mixture was found to give optimum results within 100 sec. Subsequent dehydration is in isopropanol only. The staining pattern obtained is polychrome. The distribution of colors in detail is influenced by the modes of pre- and posttreatment. Of practical interest is the development of green and greenish blue colors on collagen fibrils which contrast strongly against the pink of sarcoplasm. For this and other reasons, this RG stain version seems suitable to replace the trichrome Gomori-type trichrome stains under appropriate processing conditions.