Radio-opaque polyethylene for personalized craniomaxillofacial implants

Objective

This study aimed to present a new possibility to create radio-opaque implant material for craniomaxillofacial reconstruction.

Materials and methods

The test disks made of the own compound of polyethylenes with addiction of 2, 4, and 6 % of weight TiO₂ was investigated for cytotoxicity [each group 15 disks respectively]. Next, computed tomography of the disks was performed in environment of muscle and fat. Hardness, tensile modulus and strength, and compressive modulus and strength were tested too.

Results

Deterioration of mechanical properties of the composites containing titanium dioxide was observed [hardness, tensile modulus and strength, compressive modulus and strength, respectively: 56.7 ± 1.6 shore D, 354 ± 52, 22.5 ± 1.3, 21.8 ± 1.1, and 2995 ± 327 MPa as addiction of 2 % TiO₂; 52.0 ± 0.9 shore D, 347 ± 66, 18.0 ± 0.7, 14.2 ± 0.9, and 1396 ± 477 MPa as 4 % TiO₂; 51.3 ± 1.3 shore D, 316 ± 9, 17.4 ± 0.2, 13.6 ± 0.6, and 1100 ± 144 MPa as 6 % TiO₂ added]. The test disks revealed no cytotoxicity effect on human osteoblasts. The new material presents mild radio-opacity which was enough to observe the implant in relation to fat and muscle, but with no visible effect of beam hardening.

Conclusion

In view of the performed tests, the polyethylene enriched by titanium dioxide seems to be a proper material to consider manufacturing of craniomaxillofacial implants.

Clinical relevance

Maxilloafacial surgery is still looking for new implantologic materials. The proposed one is a new way to manufacture an implant visible in computed tomography which does not interfere with its shape in radiological examination and makes it possible to observe the surrounding soft tissues.

     

Mono- and multislice computed tomography of the orbita injury

PURPOSE: To evaluate the reliability of the mono- (SCT) and multisliced CT (MSCT) imaging and their post-processing reconstructions in the cases of orbital trauma. MATERIAL AND METHODS: the spiral monoslice (n=20) and spiral multisliced (n=5) CT studies were performed in patients suffered from orbits' injuries. CT data were reconstructed in the 2D and 3D mode. The CT original images and the 2D and 3D reconstructions were evaluated according to the quality of visualization of a pathological lesions. Surgery was the method of reference. RESULTS: The reconstructed 3D images in 16 patients examined in SCT mode and in 5 patients examined in MSCT mode allowed to recognize properly the fracture. In the 13 patients SCT and in the 3 ones MSCT revealed the bone fragments and orbital soft tissues prolapse towards maxilla sinus; including the lower rectus muscle in 6 cases. In 1 patient evaluation of the 3D model allowed to exclude communication with intracranial space. The surgery correlated well with the source images and 2D/3D SCT and MSCT models. The diagnostic quality of the raw SCT vs MSCT images was evaluated as equal, but MSCT proved to be the better source for the post processing reconstruction, because of higher resolution and better smoothing. CONCLUSIONS: - Spiral CT 2D and 3D reconstructed images, especially generated from the MSCT, more clearly than the source data depict anatomical spatial relationships; - 2D/3D reconstructions revealed the position, course and displacement of a fractured fragments; thus it supports the surgery.     

Dynamic T1 functional MRI examinations with use of blood pool contrast agent--an approach to optimization of the technique

The goal was to optimize dynamic T1 imaging for functional MRI (fMRI) examinations.For each of the 10 healthy subjects T1 3D gradient echo sequence (GRE) sequences were provided immediately after administration of blood pool contrast agent then every 2 h when subjects performed block finger tapings.Dynamic T1 fMRI is sensitive to detect cortical activations up to 6 h after BPCA administration. fMRI should be conducted within 2 h of CA administration, which is enough time for a typical fMRI experiment procedure.     

Magnetization transfer imaging--the new method of brain tissue investigation in schizophrenia

The structural abnormalities in brains of persons suffering from schizophrenia were noticed in neuropathological studies, pneumoencephalography, tomography and magnetic resonance imaging for a long time. The reduction of grey matter volume was present mainly in frontal and temporal lobes and also a decrease of total brain volume with an increase of ventricle volume was observed. The volumetric reduction of white matter was not observed. However, structural changes may not be present in each case and conventional MRI, even with high resolution images is not able to detect subtle changes which may have a functional significance. The new MRI techniques, e.g. magnetic transfer imaging (MTI), indicate the presence of changes in the white matter of schizophrenic's brains, which are not detectable by conventional MRI. MTI is based on decreasing of the signal intensity by the transfer of magnetization between saturated protons of water, bound to macromolecules of myelin and phospholipids in cell membranes and free water protons. This process may be used to estimate structural integrity of white and grey matter, to reveal the presence of subtle changes in brain tissue.