BackgroundEndolymphatic hydrops can be studied on magnetic resonance imaging (MRI) using images acquired 4 h after intravenous injection of Gd-chelate. Our aim was to compare high-resolution T2-weighted images of the saccule in normal subjects with histological sections from cadavers and to identify its changes in Meniere disease, compared to healthy volunteers.MethodsSixty-four healthy volunteers without any otologic disease and 64 patients who fulfilled all the criteria for unilateral Meniere disease underwent 3 T MRI using a T2-weighted steady state free precession (SSFP) sequence, without contrast material injection. Images of healthy volunteers were compared with histological sections of normal inner ears from premature foetuses and compared with volunteers.ResultsThe normal saccule was easily visible on T2-weighted images in volunteers, with a normal maximal height of 1.6 mm (1.4 ± 0.1 mm, mean ± standard deviation) and a good correlation with reference histological sections, while in Meniere disease the saccule was dilated in 52/62 patients (84%), with a saccular height greater than 1.6 mm (1.69 ± 0.24 mm, p = 0.001), found in 45/52 patients (86%). An associated increased width (greater than 1.4 mm) was found in 23/52 patients (44%). A round shape or the non-visualisation of the saccule were also found in 2/52 (4%) and in 5/62 patients (8%), respectively.ConclusionsA T2-weighted sequence is an easy method to diagnose Meniere disease. Saccular abnormalities were found in 84% of the cases: elongation (height > 1.6 mm) in 86%, increased saccular width in 44%, or a missing saccule in 8%.

The zygomatic arch of mammals is usually considered a phylogenetic relic of the fenestrations of the skull roof which may be observed in morphological sequences of primitive vertebrate skulls. If this concept is correct, the element is comparable (though not homologous) to the jugal arches of diapsid reptiles. Two major questions then remain unanswered: why different elements are maintained in reptiles and mammals during evolution, and why the arches are maintained as relics of ancestral forms. It is tempting to respond to the latter question with a very simple answer, namely that the elements function in order to sustain mechanical stresses. In this paper, we raise the questions which quality of stresses occurs in a primate skull within the zygomatic arches and what relationship these stresses hold to the morphology of these bony elements. An answer has been sought by means of finite element stress analysis. We found that the zygomatic arch in primate skulls represents a structure which carries, under all biologically relevant conditions, either compressive or tensile stresses. In a very simple model of the human skull under bite forces, a strip of stresses occurs lateral to the orbits, which seems roughly comparable to the zygomatic arch. Once such a structure exists and is used as an insertion of adductor muscles, it will be exposed to bending stress in side view and in frontal view. Morphological details of the zygomatic arch (curvature, profile, suture) are well suited to sustain the evoked stresses by a minimum of material.

BACKGROUND AND PURPOSE:Hypoattenuated foci in the otic capsule are routinely identified on multidetector CT (MDCT), particularly in pediatric patients. We aimed to describe and characterize the hypoattenuated focus in the anterior otic capsule.

The main nerves of the pelvis and lower limbs arise from the lumbar and sacral plexuses. These nerves can be affected by any of a large number of pathologic processes that occur in the paravertebral and pelvic regions. Understanding of the neurological findings related to paravertebral and pelvic pathology needs complete and accurate knowledge of the anatomy of these regions. The axial transverse sections of computed tomography give perfect visualisation of the anatomy of osseous, muscular, and vascular structures of the vertebral and paravertebral area and pelvic walls. Visualisation of the nerves in this regions is much more difficult, because direct demonstration of nervous structures by computed tomography is usually impossible. To be able to identify components of the lumbosacral plexus on axial CT sections the radiologist has to know the location of the nervous structures and the relationships of these structures to vascular, muscular and osseous structures which are easily demonstrated.

High-resolution sagittal magnetic resonance images depict an oval area in the dermis beneath the nail matrix that gives a particular signal. This study defines the magnetic resonance imaging characteristics of this area and examines its correlation with the lunula. A high-resolution surface gradient coil specially designed for skin imagining was used on a 1.5 T magnetic resonance unit. The subnail matrix (SNM) areas of 12 subjects had a significantly longer T2 relaxation time and a higher enhancement ratio after injection of gadolinium than did the nail bed dermis. The length of the SNM area distal to the free edge of the proximal nail fold was highly correlated with the length of the lunula (R = 0.98) in 30 fingers and 10 toes. The total length of the SNM area was somewhat correlated with the nail thickness (R = 0.86) in 30 fingers. The histology and microvascularization of the subungual tissue in 21 fingers showed that this SNM area had specific features: The area was composed of loose connective tissue without bundles, and the reticular and subdermal vascular networks had large regular meshes in this oval area. The lunula is shown to be linked to a well-defined area in the underlying dermis with a specific histology and microvascularization.