MRI signal-based quantification of subchondral bone at the tibial plateau: a population study

Objective

To determine whether differences in subchondral sclerosis at the tibial plateau could be detected with magnetic resonance (MR) imaging in two different age groups.

Materials and methods

This was a retrospective hypothesis-testing study. Thirty-two knees in group A (25–30 year olds) and 32 knees in group B (45–50 years old) were included. Participants had no MR features of osteoarthritis (OA). On coronal images, tibial articular cartilage thickness was measured, and regions of interest were created in the medial and lateral tibial plateau subchondral bone and in the tibial metaphysis. The measure of heterogeneity at the tibial plateaux was the ratio of the standard deviation of the signal in the medial/lateral compartment to the standard deviation of the signal in the metaphysis (ratio of standard deviations - RSS_medial/RSS_lateral). Differences between groups were assessed using unpaired Student’s t-tests.

Results

Mean RSS_medial was 2.61 (standard deviation, SD?=?0.77) in group A and 2.97 (SD?=?0.59) in group B. Mean RSS_lateral in group A was 1.86 (SD?=?0.63) and 1.89 (SD?=?0.43) in group B. Mean total cartilage thickness (in mm) in group A was 3.38 (SD?=?0.90) for the medial and 3.90 (SD?=?1.09) for the lateral compartment and 3.44 (SD?=?0.74) for the medial and 3.96 (SD?=?0.96) for the lateral compartment in group B. The only parameter to show a statistically significant difference between groups was RSS_medial (p?=?0.04).

Conclusion

A difference in medial subchondral bone sclerosis between two age groups was demonstrated in the absence of MR features of OA. This may represent the earliest OA change detectable on MR imaging.     

Cryptococcus and Cryptococcosis in Cuba. A minireview

Cryptococcosis has emerged as an important public health problem in Africa, Asia and the Americas due to the increasing numbers of persons at risk of this infection and the adaptation of its aetiological agents to new environments. The proper management requires early recognition of Cryptococcus neoformans/C. gattii species complex infection, familiarity with the use and limitations of diagnostic tests and knowledge of the available treatment options. This review will address these issues with the goal of providing sufficient information to suspect, diagnose and treat patients with cryptococcosis based on Cuban data and review of the literature.     

Diffusion-weighted MRI of denervated muscle: a clinical and experimental study

Objective  The aim of this study was to investigate skeletal muscle denervation using diffusion-weighted magnetic resonance imaging (DWMRI). Materials and methods  Sciatic nerve axotomy was performed in a group of nine New Zealand White rabbits, and electromyographic (EMG), pathological, and DWMRI studies were conducted on ipsilateral hamstring muscles 1 and 8 days after axotomy. In addition, DWMRI studies were carried out on leg muscles of ten patients with acute and subacute lumbosacral radiculopathy. Results  High intensity signals on short tau inversion recovery (STIR) magnetic resonance imaging and an increased apparent diffusion coefficient (ADC) were observed in denervated muscles of the animals 1 and 8 days after axotomy as well as in denervated muscles of the patients with radiculopathy. In the clinical study, ADC was 1.26 ± 0.18 × 10⁻⁹ m²/s in normal muscle and increased to 1.56 ± 0.23 × 10⁻⁹ m²/s in denervated muscles (p = 0.0016). In animals, EMG and muscle pathological studies were normal 1 day after axotomy, and the muscles demonstrated spontaneous activity on EMG and neurogenic atrophy on histological studies 7 days later. Conclusion  This DWMRI study demonstrates that enlargement of extracellular fluid space in muscle denervation is an early phenomenon occurring several days before the appearance of EMG and histological abnormalities. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Nathalie Holl and Andoni Echaniz-Laguna contributed equally to this work.     

Regional migratory osteoporosis

Regional migratory osteoporosis (RMO) is an uncommon disease characterised by a migrating arthralgia involving the weight bearing joints of the lower limb. The typical imaging findings on radiographs, magnetic resonance imaging, computed tomography and bone scintigraphy are described and illustrated. Men in their fifth and sixth decades of life are most commonly affected. The most common presentation is with proximal to distal spread in the lower limb. The world literature has been reviewed which has revealed 63 documented cases of regional osteoporosis or bone marrow oedema with migratory symptoms. Most of these cases have not been labelled as RMO and therefore the condition is probably under-diagnosed. The radiology of RMO is indistinguishable from transient osteoporosis of the hip (TOH) except for the migratory symptoms and the two conditions are likely to be part of the same spectrum of disease. Systemic osteoporosis is a more recently recognised accompanying feature that hints at an underlying aetiology and an approach to the management of this condition.     

Orthographic and associative neighborhood density effects: What is shared,what is different?

Words with many orthographic neighbors elicit a larger N400 than words with few orthographic neighbors. This has been interpreted as stronger overall semantic activation due to orthographic neighbors activating their semantic representations. To investigate this claim, we manipulated the number of associates of words (NoA), a variable directly affecting overall semantic activation, and compared this to the ERP effect of the number of orthographic neighbors (N) in a lexical decision task. Words with high NoA and with high N produced a very similar increase of the N400. In addition, a higher N increased the amplitude of the Late Positive Complex. The common N400 effect suggests that N affects semantic activation, like NoA does. The late positive effect specific to N could occur because words with few orthographic neighbors initially elicit little activity in the orthographic system, thereby resembling nonwords, which leads to distinct processing.     

Presence of substance P and angiotensin II in corticotropic cells of the lizard Gallotia galloti: immunochemical study in the adult and during ontogenesis.

The hypophysis of the lizard Gallotia galloti showed substance-P-like immunoreactivity in both the adenohypophysis (pars distalis, PD; pars intermedia, PI) and the neurohypophysis (median eminence and pars nervosa), whereas angiotensin-II-like immunoreactivity appeared only in PD and PI. The elution-restaining procedure has allowed us to demonstrate the colocalization of both peptides with adrenocorticotropic hormone (ACTH) in PD and PI cells. Electron microscopic study revealed the presence of substance P immunoreactivity on ACTH secretory granules. The ontogeny of both peptides in corticotropic cells has been studied, revealing that the presence of substance P in ACTH-containing cells of the PI occurs from the embryonic stage 33 (S 33), whereas in the PD it occurs from S 34, coinciding with the appearance of ACTH within the same cells. In both median eminence and pars nervosa of the neurohypophysis, substance P appeared later in development, at S 38. Angiotensin II immunoreactivity in PI cells first appeared at S 38, while in PD it appeared from S 40.