Experimental model to evaluate in vivo and in vitro cartilage MR imaging by means of histological analyses

OBJECTIVES: Implementation of an experimental model to compare cartilage MR imaging by means of histological analyses. MATERIAL AND METHODS: MRI was obtained from 4 patients expecting total knee replacement at 1.5 and/or 3T prior surgery. The timeframe between pre-op MRI and knee replacement was within two days. Resected cartilage-bone samples were tagged with Ethi((R))-pins to reproduce the histological cutting course. Pre-operative scanning at 1.5T included following parameters for fast low angle shot (FLASH: TR/TE/FA=33ms/6ms/30 degrees , BW=110kHz, 120mmx120mm FOV, 256x256 matrix, 0.65mm slice-thickness) and double echo steady state (DESS: TR/TE/FA=23.7ms/6.9ms/40 degrees , BW=130kHz, 120x120mm FOV, 256x256 matrix, 0.65mm slice-thickness). At 3T, scan parameters were: FLASH (TR/TE/FA=12.2ms/5.1ms/10 degrees , BW=130kHz, 170x170mm FOV, 320x320, 0.5mm slice-thickness) and DESS (TR/TE/FA=15.6ms/4.5ms/25 degrees , BW=200kHz, 135mmx150mm FOV, 288x320matrix, 0.5mm slice-thickness). Imaging of the specimens was done the same day at 1.5T. MRI (Noyes) and histological (Mankin) score scales were correlated using the paired t-test. Sensitivity and specificity for the detection of different grades of cartilage degeneration were assessed. Inter-reader and intra-reader reliability was determined using Kappa analysis. RESULTS: Low correlation (sensitivity, specificity) was found for both sequences in normal to mild Mankin grades. Only moderate to severe changes were diagnosed with higher significance and specificity. The use of higher field-strengths was advantageous for both protocols with sensitivity values ranging from 13.6% to 93.3% (FLASH) and 20.5% to 96.2% (DESS). Kappa values ranged from 0.488 to 0.944. CONCLUSIONS: Correlating MR images with continuous histological slices was feasible by using three-dimensional imaging, multi-planar-reformat and marker pins. The capability of diagnosing early cartilage changes with high accuracy could not be proven for both FLASH and DESS.

A Surface Displacement Analysis for Volcan Pacaya from October 2001 through March 2013 by Means of 3-D Modeling of Precise Position GPS Data

Volcán Pacaya is one of three currently active volcanoes in Guatemala. Volcanic activity originates from the local tectonic subduction of the Cocos plate beneath the Caribbean plate along the Pacific Guatemalan coast. Pacaya is characterized by generally strombolian type activity with occasional larger vulcanian type eruptions approximately every ten years. One particularly large eruption occurred on May 27, 2010. Using GPS data collected for approximately 8 years before this eruption and data from an additional three years of collection afterwards, surface movement covering the period of the eruption can be measured and used as a tool to help understand activity at the volcano. Initial positions were obtained from raw data using the Automatic Precise Positioning Service provided by the NASA Jet Propulsion Laboratory. Forward modeling of observed 3-D displacements for three time periods (before, covering and after the May 2010 eruption) revealed that a plausible source for deformation is related to a vertical dike or planar surface trending NNW-SSE through the cone. For three distinct time periods the best fitting models describe deformation of the volcano: 0.45 right lateral movement and 0.55 m tensile opening along the dike mentioned above from October 2001 through January 2009 (pre-eruption); 0.55 m left lateral slip along the dike mentioned above for the period from January 2009 and January 2011 (covering the eruption); -0.025 m dip slip along the dike for the period from January 2011 through March 2013 (post-eruption). In all bestfit models the dike is oriented with a 75° westward dip. These data have respective RMS misfit values of 5.49 cm, 12.38 cm and 6.90 cm for each modeled period. During the time period that includes the eruption the volcano most likely experienced a combination of slip and inflation below the edifice which created a large scar at the surface down the northern flank of the volcano. All models that a dipping dike may be experiencing a combination of inflation and oblique slip below the edifice which augments the possibility of a westward collapse in the future.

[Management of a failing implant supporting a bar-retained maxillary overdenture by means of alveolar ridge augmentation. Implant loss and reimplantation]

This case report presents the treatment sequence of a 56 years old patient after he developed periimplantitis at the implant in position of tooth 22. This implant was integrated in an overdenture reconstruction connected to a soldered screw retained gold bar. The entire 2-stage procedure of implant explantation, simultaneous bone augmentation and new implant placement is documented. The onlay-graft was performed by means of the Transfer-Ring-Control System (Meisinger). The existing gold bar could be resoldered and adapted to the new implant. Accordingly the overdenture was relined and the female retainer mounted. The treatment period covered almost one year.

Does homeopathically potentized antimony stimulate coagulation? A summary of previous findings and results of an in vitro pilot study by means of thrombelastography

BACKGROUND: Potentized antimony is traditionally used in anthroposophic medicine to enhance hemostasis in bleeding disorders, but evidence of its effectiveness is scarce. On the other hand, non-toxic and economic additional therapeutic options for hemostatic disorders are desirable. OBJECTIVES: We examined all available literature on the subject and performed a controlled pilot in vitro study to test the procoagulatory potency of antimony D 5. DESIGN: Freshly drawn citrated whole blood of 12 healthy volunteers and 12 patients with bleeding disorders was equally distributed into 344 portions, after which it was mixed with antimony D 5, or its potentized vehicle (lactose D 5) as control solution and tested with thrombelastography. The paired t-test and the Wilcoxon signed rank test were used for statistical analysis. In 5 of the 12 healthy donors, a second blood sample was drawn to assess individual variability and increase the total number of replicates. Thus three separate calculations were performed: for the 12 patients, the 12 healthy donors, and the 5 later samples from the same donors. The analysis was exploratory, and no Bonferroni correction was applied. RESULTS: In the antimony D5 samples of the 12 healthy subjects, but not the patients, there was a tendency toward a shorter clotting time (CT) (p = 0.074) and a trend for an increased clot firmness, expressed as maximal amplitude (MA) (p = 0.058). The increase of MA was significant (p = 0.011) when the later samples were included. No statistical difference was detected for the clot formation time and the clot lysis index. CONCLUSION: The exploratory results of this pilot study are inconclusive as to whether antimony D5 has a procoagulatory effect in vitro, although the results suggest an effect on MA and possibly CT. More research is warranted.