Janusz Skrzat

Error estimation of the fractal dimension measurements of cranial sutures

The fractal exponents used to quantify the complexity of cranial sutures were computed for 17 coronal and 17 sagittal sutures of adults from different populations, using the box‐counting algorithm. This paper discusses the main sources of error for the fractal exponents, and gives the error estimates. We then compare our results with those obtained by other authors. We suggest that the usual error estimates implied by the standard deviation for the regression line are too low. We emphasize the crucial role played by the choice of regression line in the log–log plot. For the coronal and sagittal sutures we found mean fractal dimensions of 1.48 and 1.56, respectively. Our values are close to the value for Brownian random walk.

Microanatomical study of the recurrent artery of Heubner.

The purpose of this study has been to describe the microanatomy of the recurrent artery of Heubner (RAH) in detail, to deepen anatomical knowledge and aid neurosurgeons in their work. The material was obtained from cadavers (ages 31-75 years) at routine autopsy. A total of 70 human brains (39 male and 31 female) were examined. People who died due to neurological disorders were not included in the study. Right after dissection, the arteries were perfused with acrylic paint emulsion, through the Circle of Willis or electively through the RAH. Brains were fixed in a 10% solution of formaldehyde, sectioned and placed in methyl salicylate for tissue transparency. To obtain corrosion-casts, the vessels were perfused with polyvinyl chloride or Mercox CL-2R resin and corroded using concentrated potassium chloride. The obtained material was analyzed using a stereoscopic light microscope. The RAH was present in 138 hemispheres with a mean of 1.99 RAH per hemisphere (275 RAH in total). The mean RAH length was 25.2 mm and the mean RAH diameter, in its place of origin, was 1 mm. Two to 30 branches (mean=9.4) originated from the stem of the RAH. The number of RAHs showed a negative correlation to the number of arteries from the medial group of lenticulo-striate arteries (LSA) (R=-0.62; p < 0.0001) which branch off the middle cerebral artery (MCA). This study further supports the RAH embryologic theory by Abbie. The RAH, in its extra- and intracerebral course, may join with the middle group of the LSA or directly with the MCA.

Extra- and intracerebral course of the recurrent artery of Heubner.

BACKGROUND The aim of the current study was to analyse the extra- and intracerebral course of the recurrent artery of Heubner (RAH) to provide detailed information for neurosurgeons operating in this area. MATERIALS AND METHODS The material for this study was obtained from cadavers (ages 31-75 years) during routine autopsies. A total of 70 human brains (39 male and 31 female) were examined. The material was collected not later than 48 h post-mortem. People who died due to neurological disorders were not included into the study. Right after dissection the arteries were perfused with either acrylicpaint emulsion, polyvinyl chloride or Mercox CL-2R resin, through the Circle of Willis or electively through the RAH. The obtained material was analysed using a stereoscopic light microscope, magnification 2-40´. RESULTS The RAH was present in 138 hemispheres with a mean of 1.99 RAH per hemisphere (275 RAH in total). The mean RAH length was 25.2 mm and the mean RAH diameter, in its place of origin, was 1 mm. In 168 (61%) cases the RAH ran superiorly, in 88 (32%) cases anteriorly, in 11 (4%) cases inferiorly and in 8 (3%) cases posteriorly to the A1 segment. In 70.2% of the cases the course of the RAH was parallel to the anterior communicating artery A1 segment, and in 29.8% of the cases the RAH arched towards the olfactory tract. As the extracerebral course of the RAH was always tortuous,its length was 1 to 5 times the distance between its place of origin and the most lateral point of anterior perforated substance (APS) penetration. The intracerebral course of the RAH was almost always univectorial - towards the head of the caudate nucleus.The course of RAH branches depended on their number. When the number of RAH sand their branches was low, they separated immediately after penetrating the APS and formed multiple small branches. When the number of RAHs and branches was high,post-APS branching was less frequent and occurred in distal segments. CONCLUSIONS The origin and course of the RAH is highly variable. The RAH, in its extra- and intracerebral course, may join with the middle group of the lenticulostriate arteries or directly with the middle cerebral artery. This artery should be routinely identified during anterior communicating artery aneurysm clipping to prevent postoperative neurological deficits.

Three dimensional visualisation and morphometry of bone samples studied in microcomputed tomography (micro-CT)

This article highlights the utility of micro-computed tomography (micro-CT) for characterisingmicroscale bone morphology. For this purpose we tested selected samplesof the human bones (Wormian bone, rib, lumbar vertebra) to reconstruct externaland internal morphological features. Selected bony samples were investigatedusing a micro-CT scanner (Skyscan 1172, N.V., Aartselaar, Belgium). The imageresolution of scans varied from 5 to 27 μm/pixel depending on the bone sample.We used CTvox software (by Skyscan) to perform volume rendering of the samples.Further, 3-dimensional geometrical models were reconstructed using theCTvol application. Such models enabled graphical distinction between osseouscomponents of various morphology and were used to visualise the Haversian canalsystem inside the compact bone of the rib. Applying a modified transfer functionfor volume rendering we presented the overall morphology of the Wormian boneand small vascular channels penetrating its interior. As an example of quantitativeanalysis based on micro-CT scans we compared the trabecular structure of thelumbar vertebrae with CTAn software. Significant differences in percent bonevolume (BV/TV) were determined. Micro-CT was found to be a very accurate andhelpful method to study small anatomical structures of the bones in micro scale.

Micro-computed tomography study of the abnormal osseous extensions of sella turcica

The paper presents anatomical considerations on the abnormal ossification, which occurred around the dorsum of the sella turcica in the human skull of the female individual. Probably the morphological alterations of the sellar region were associated with extensive heterotopic ossification of the dura mater attached to the dorsum of the sella turcica and the posterior clinoid processes. The analysis of gray values of the voxels representing the areas of abnormal ossification indicated on variation in bone density in the entire sample. We have established that the highest mineralisation of bony tissue occurred in the marginal parts of the osseous extensions deriving from the posterior clinoid processes. The ossified parts of dura mater attached to the posterior clinoid processes showed significantly higher content of the hydroxyapatite (1.9 g/cm3) than the dorsum of the sella turcica (1.0 g/cm3).

Topography and morphometry of the subarcuate canal

The current study shows in a close-up view anatomical relationship between the subarcuate canal and the osseous labyrinth. For this purpose we used micro-computed tomography which allowed performing three-dimensional reconstruction of the subarcuate canal and gave adequate data for estimation its diameter across its course. The diameter of the middle part (the most uniform) of the subarcuate canal varied from 0.28 mm to 0.46 mm. Hence, we calculated the centre of mass for each cross-section of the separated subarcuate canal. This procedure helped us to visualise trajectory of the subarcuate canal and its spatial orientation within the petrous bone. From our data we concluded that subarcuate canals revealed not well defined trajectories and their spatial orientation varied across the studied temporal bones.

Contemporary views on the ossification of the ligamenta flava.

The ligamenta flava, together with the vertebral lamina, form the posterior wall of the spinal canal. Since they are located immediately adjacent to the nerve structures of the spinal cord, every pathology that involves hypertrophy produces neurological disturbances as a result. One of the most common reasons for hypertrophy of the ligamenta flava is heterotopic ossification. The main regions of the world where this disorder occurs are the Asian countries, especially Japan, but there are increasing numbers of such cases in other populations. The most important causes of the formation of ectopic osseous tissue in the vicinity of the ligamenta flava are thought to be mechanical stress and genetic predisposition. Treatment is mostly limited to surgical procedures. The present study is a review of the current state of our knowledge concerning the ossification of the ligamenta flava, the sequelae of this pathology, and the treatment methods.

Anatomy of the fundus of the internal acoustic meatus — micro-computed tomography study

The aim of this paper was to present micro-computed tomography (micro-CT) high resolution images of the fundus of internal acoustic meatus (FIAM) and characterise the normal appearance of its singular areas which are places of passage of numerous anatomical structures. By using micro-CT we obtain detailed volume rendering images presenting topography of the FIAM in 3-dimensional (3D) space. We figured out that 3D reconstructions obtained from micro-CT scans can precisely demonstrate all areas of the FIAM (facial nerve area, cochlear area, superior and inferior vestibular areas, singular foramen). Application of this technique allows finding out new anatomical structures like the foramen of the transverse crest, which is not described in literature. Hence, we estimated the size of each area of the FIAM by measuring their minimal and maximal diameter. In the studied material we did not find out any statistically significant difference between mean diameters calculated for infant and adult individuals.

The scaphocephalic skull of an adult male.

The paper presents abnormal craniofacial morphology of an adult male afflicted with premature closure of the sagittal suture. The skull is well preserved and there are no visible traits of surgical management which would be aimed to correctcranial deformation. In consequence of the restricted cranial development, some diameters of the skull were significantly altered. Basically, cranial vault morphology fits apparently to the scaphocephaly, whereas the basic ranium and viscerocranium are altered only in minor degree.

A preliminary study of three-dimensional reconstruction of the human osseous labyrinth from micro-computed tomography scans

The adult human temporal bone was investigated using micro-CT scans. Various aspects of the osseous labyrinth were presented in figures which are effect of the volume rendering. The 3D reconstructions were performed to visualize the cochlea and the semicircular canals embedded in the petrous bone. The final product of this study was a digital three-dimensional model of the entire osseous labyrinth which can be viewed at different angles on the computer screen.