Philipp Gruber

Variability of Human Foramen Magnum Size

The foramen magnum is an important landmark of the skull base and is of particular interest for anthropology, anatomy, forensic medicine, and other medical fields. Despite its importance, few osteometric studies of the foramen magnum have been published so far. A total of 110 transverse and 111 sagittal diameters from Central European male and female dry specimens dating from the Pleistocene to modern times were measured, and related to sex, age, stature, ethnicity, and a possible secular trend. Only a moderate positive correlation between the transverse and the sagittal diameter of the foramen magnum was found. Surprisingly, neither sexual dimorphism, individual age‐dependency, nor a secular trend was found for either diameter. Furthermore, the relationship between the individual stature and foramen magnum diameters was weak: thus foramen magnum size cannot be used as reliable indicator for stature estimation. Further consideration of possible factors influencing the variability of human foramen magnum size shall be explored in larger and geographically more diverse samples, thus serving forensic, clinical, anatomical, and anthropological interests in this body part. Anat Rec, 2009.

A Generative Probabilistic Model and Discriminative Extensions for Brain Lesion Segmentation— With Application to Tumor and Stroke

We introduce a generative probabilistic model for segmentation of brain lesions in multi-dimensional images that generalizes the EM segmenter, a common approach for modelling brain images using Gaussian mixtures and a probabilistic tissue atlas that employs expectation-maximization (EM), to estimate the label map for a new image. Our model augments the probabilistic atlas of the healthy tissues with a latent atlas of the lesion. We derive an estimation algorithm with closed-form EM update equations. The method extracts a latent atlas prior distribution and the lesion posterior distributions jointly from the image data. It delineates lesion areas individually in each channel, allowing for differences in lesion appearance across modalities, an important feature of many brain tumor imaging sequences. We also propose discriminative model extensions to map the output of the generative model to arbitrary labels with semantic and biological meaning, such as “tumor core” or “fluid-filled structure”, but without a one-to-one correspondence to the hypo- or hyper-intense lesion areas identified by the generative model. We test the approach in two image sets: the publicly available BRATS set of glioma patient scans, and multimodal brain images of patients with acute and subacute ischemic stroke. We find the generative model that has been designed for tumor lesions to generalize well to stroke images, and the extended discriminative -discriminative model to be one of the top ranking methods in the BRATS evaluation.

History of Spinal Disorders

The French pediatrician Nicholas Andry (1658–1742), considered the father of orthopedics, coined the word “orthopaedic”, which is made up of two Greek words, “orthos”, meaning straight, and “paidion”, meaning child (Fig. 1a) [3]. The term “orthopaedic” was used for the first time in the epoch-making textbook of Andry published in 1741. Open image in new window

Stroke Lesion Segmentation Using a Probabilistic Atlas of Cerebral Vascular Territories

The accurate segmentation of lesions in magnetic resonance images of stroke patients is important, for example, for comparing the location of the lesion with functional areas and for determining the optimal strategy for patient treatment. Manual labeling of each lesion turns out to be time-intensive and costly, making an automated method desirable. Standard approaches for brain parcellation make use of spatial atlases that represent prior information about the spatial distribution of different tissue types and of anatomical structures of interest. Different from healthy tissue, however, the spatial distribution of a stroke lesion varies considerably, limiting the use of such brain image segmentation approaches for stroke lesion analysis, and for integrating brain parcellation with stroke lesion segmentation. We propose to amend the standard atlas-based generative image segmentation model by a spatial atlas of stroke lesion occurrence by making use of information about the vascular territories. As the territories of the major arterial trees often coincide with the location and extensions of large stroke lesions, we use 3D maps of the vascular territories to form patient-specific atlases combined with outlier information from an initial run, following an iterative procedure. We find our approach to perform comparable to (or better than) standard approaches that amend the tissue atlas with a flat lesion prior or that treat lesion as outliers, and to outperform both for large heterogeneous lesions.

Ischias – Von der Säftelehre zur Pathomorphologie

ZusammenfassungHeute zählt der lumbale Bandscheibenvorfall zu einem der häufigsten Krankheitsbilder, das sowohl in der Hausarztpraxis als auch in den jeweiligen Fachsprechstunden der Orthopädie, Neurologie, Rheumatologie oder Neurochirurgie gesehen wird. Zudem ist die mikrochirurgische Diskektomie einer der am meist durchgeführten wirbelsäulenchirurgischen Eingriffe überhaupt. Über Jahrhunderte hinweg war die diskogene Nervenkompression ein wenig verstandenes und nicht klar abgegrenztes Krankheitsbild, für das es auch keine spezifischen und wirkungsvollen Therapien gab. Zwar haben die hippokratischen Ärzte diese Beschwerden bereits gekannt, welche sie dann auch als „Ischias“ bezeichneten, aber sie subsumierten unter diesem Begriff unterschiedliche Krankheitsbilder wie zum Beispiel auch Hüftbeschwerden. Es war erst das Verdienst von Domenico Felice Antonio Cotugno (1736–1822) Mitte des 18. Jahrhunderts, der begriffliche Klarheit in das Krankheitsbild Ischias brachte und diese Beschwerden als eine neurogen bedingte Krankheit begriff. Ebenso stammt aus dieser Zeit die erste eindeutige Beschreibung der Bandscheibe durch Josias Weitbrecht (1702–1747). Erst 1858 beschrieb dann Hubert von Luschka (1820–1875) pathoanatomisch einen Bandscheibenvorfall. 1908 hatten der Neurologe Oppenheim und der Chirurg Feodor Krause eine Bandscheibenoperation initiiert und erfolgreich durchgeführt, haben aber die Pathologie als solche verkannt. Es waren schlussendlich William Jason Mixter (1880–1958) und Joseph Seaton Barr (1901–1963), die 1934 der diskogen bedingten Nervenkompression als Krankheitsbild und ihrer chirurgischen Therapie zum Durchbruch verhalfen.AbstractToday, lumbar disc disease is a very common disease, which will be often seen in both the family practice as well as in the consultations of orthopedics, neurology, rheumatology or neurosurgery. Furthermore, lumbar disc surgery is one of the most common spinal surgical procedures worldwide. But, for many centuries, physician had no clear understanding of the anatomical condition and the pathomechanism of this disease. Therefore, no rational treatment was available. The Hippocratic physicians knew the signs and symptoms of lumbar disc disease, which they then called “sciatica”. But, they subsumed different disorders, like hip diseases under this term. In the mid-18th century, it was the Italian physician Domenico Felice Antonio Cotugno (1736–1822), who first brought clarity in the concept of radicular syndromes; he recognized, that the so-called “sciatica” could be of neurogenic origin. In 1742, a contemporary of Cotugno, the German Josias Weitbrecht (1702–1747) has to be credited for the first precise description of the intervertebral disc. Nearby a hundred years later, the German Hubert von Luschka (1820–1875) described for the first time a herniated disc in a pathologic specimen. With the landmark report of the New England Journal of Medicine in 1934, the two American surgeons, William Jason Mixter (1880–1958) and Joseph Seaton Barr (1901–1963), finally cleared the pathomechanism of lumbar disc disease.