Three-dimensional imaging of the petrous bone for the middle fossa approach to the internal acoustic meatus: an experimental study

Quantitative anatomy of the growing clavicle in the human fetus: CT, digital image analysis, and statistical study

Purposes

Knowledge of dimensions of fetal long bones is useful in both the assessment of fetal growth and early detection of inherited defects. Measurements of the fetal clavicle may facilitate detection of numerous defects, e.g., cleidocranial dysplasia, Holt–Oram syndrome, Goltz syndrome, and Melnick–Needles syndrome.

Methods

Using the methods of CT, digital image analysis, and statistics, the size of the growing clavicle in 42 spontaneously aborted human fetuses (21 males and 21 females) at ages of 18–30 weeks was studied.

Results

Without any male–female and right–left significant differences, the best fit growth models for the growing clavicle with relation to age in weeks were as follows: y = −54.439 + 24.673 × ln(age) ± 0.237 (R² = 0.86) for length, y = −12.042 + 4.906 × ln(age) ± 0.362 (R² = 0.82) for width of acromial end, y = −4.210 + 2.028 × ln(age) ± 0.177 (R² = 0.77) for width of central part, y = −4.687 + 2.364 × ln(age) ± 0.242 (R² = 0.70) for width of sternal end, y = −51.078 + 4.174 × ln(age) ± 6.943 (R² = 0.82) for cross-sectional area, and y = −766.948 + 281.774 × ln(age) ± 19.610 (R² = 0.84) for volume.

Conclusions

With no sex and laterality differences, the clavicle grows logarithmically with respect to its length, width, and volume, and linearly with respect to its projection surface area. The obtained morphometric data of the growing clavicle are considered normative for their respective weeks of gestation and may be of relevance in the diagnosis of congenital defects.

Morphometric study of the two fused primary ossification centers of the clavicle in the human fetus

Purposes

A satisfactory understanding of the clavicle development may be contributing to both the diagnosis of its congenital defects and prevention of perinatal damage to the shoulder girdle. This study was carried out to examine the transverse and sagittal diameters, cross-sectional area and volume of the two fused primary ossification centers of the clavicle.

Methods

Using the methods of CT, digital-image analysis and statistics, the size for two fused primary ossification centers of the clavicle in 42 spontaneously aborted human fetuses at ages of 18–30 weeks was studied.

Results

Without any male–female and right-left significant differences, the best fit growth models for two fused primary ossification centers of the clavicle were as follows: y = −31.373 + 15.243 × ln(age) ± 1.424 (R² = 0.74) for transverse diameter, y = −7.945 + 3.225 × ln(age) ± 0.262 (R² = 0.78), y = −4.503 + 2.007 × ln(age) ± 0.218 (R² = 0.68), and y = −4.860 + 2.117 × ln(age) ± 0.200 (R² = 0.73) for sagittal diameters of the lateral, middle and medial ends respectively, y = −31.390 + 2.432 × age ± 4.599 (R² = 0.78) for cross-sectional area, and y = 28.161 + 0.00017 × (age)⁴ ± 15.357 (R² = 0.83) for volume.

Conclusions

With no sex and laterality differences, the fused primary ossification centers of the clavicle grow logarithmically in both transverse and sagittal diameters, linearly in cross-sectional area, and fourth-degree polynomially in volume. Our normative quantitative findings may be conducive in monitoring normal fetal growth and screening for inherited faults and anomalies of the clavicle in European human fetuses.

Accuracy of computer-aided geometric three-dimensional reconstruction of the human petrous bone based on serial unstained celloidin sections

The aim of this study was to present a comprehensive three-dimensional (3D) morphology of the petrous bone with computer image-processing technology, which could be beneficial for the teaching of anatomy and for surgical procedures. The unstained celloidin sections of human temporal bone were digitized with high resolution and quality, and then processed with Amira^® software to include alignment, segmentation and reconstruction. The integral structure of the human inner ear was presented with computer modeling, including the petrous bone, bone labyrinth, internal carotid artery canal, internal jugular vein canal, sigmoid sinus, inferior petrosal sinus, glossopharyngeal meatus, vagal meatus, internal acoustic meatus, facial nerve canal, greater superficial petrosal nerve, vestibular aqueduct, extraosseous portion of the endolymphatic sac, round and oval window, processus cochleariformis and pyramidal eminence. The 3D model showed detailed structure of the external and internal petrous bone, as well as their spatial relationship. The present study suggests the feasibility of comprehensive 3D reconstruction of the petrous bone using unstained celloidin sections, which may provide advantages for future study.

The middle cranial fossa: morphometric study and surgical considerations

The anatomical features of the temporal bone can vary significantly among different individuals. These variations affect the operative view in middle cranial fossa surgery. We performed 18 middle fossa approaches in 9 cadaveric heads, with detailed morphological analysis, to identify unfavorable situations and reliable systems to avoid complications during surgery. We recorded linear, angular measurements and calculated areas. We performed a computed tomography (CT) scan with analysis of the amount of bone to remove in two temporal bones. We found that the location of the internal auditory canal (IAC) is the keystone of bone removal. We also found accuracy in the system suggested by E. and J. L. Garcia-Ibanez for its identification and that there is a smaller surgical window in female patients (statistically significant) that can be predicted on preoperative imaging studies. Our study also confirms significant individual variability in the mutual relationships of different surgical landmarks. We concluded that surgery of the middle fossa requires detailed understanding of the complex temporal bone anatomy. The surgeon has to be aware of extreme variability of the more commonly used anatomical landmarks. The method to identify the position of the IAC described by E. and J. L. Garcia-Ibanez seems to be the simplest and most reliable. When the surgical strategy includes an anterior petrosectomy, interindividual variability can critically affect the working area, particularly in females. The working area can be estimated on preoperative CT scans through the petrous bone.