MRI of the hypothalamic-pituitary axis in children

In childhood, the MR characteristics of the normal pituitary gland are well established. During the first 2 months of life the adenohypophysis demonstrates high signal. Pituitary gland height (PGH) decreases during the 1st year of life and then increases, reaching a plateau after puberty. The magnetization transfer ratio (MTR) increases in both sexes up to the age of 20 years. On dynamic contrast-enhanced studies, the posterior pituitary lobe enhances simultaneously with the straight sinus, and the adenohypophysis later, but within 30 s. In genetically determined dysfunctional states, the adenohypophysis may be normal, hypoplastic, or enlarged. Pituitary enlargement, observed in Prop 1 gene mutations, is characterized by a mass interposed between the anterior and posterior lobes. An ectopic posterior lobe (EPP), associated with a hypoplastic or absent pituitary stalk, may be observed in patients with hypopituitarism. Tumors of the hypothalamic-pituitary (HP) axis may be the origin of adenohypophyseal deficiencies. A small hypointense adenohypophysis is found in iron overload states and is often associated with hypogonadotrophic hypogonadism. Absence of the posterior lobe bright signal, with or without a thick pituitary stalk or a mass at any site from the median eminence to the posterior pituitary lobe, may be found in diabetes insipidus. Hydrocephalus, suprasellar arachnoid cysts, hypothalamic hamartomas and craniopharyngiomas may result in central precocious puberty (CPP). Increased PGH in girls with idiopathic CPP is useful for its differential diagnosis from premature thelarche (PT). Pituitary adenomas, observed mainly in adolescents, present the same MR characteristics as those in adults.     

In vivo monitoring of cutaneous edema using spectral imaging in the visible and near infrared

Tissue inflammation is often accompanied by local interstitial fluid accumulation expressed as edema. Edema can be the manifestation of infection, lymphatic blockage, wound healing, or even cancer, and is typically graded visually. Here we demonstrate that the edema reaction can be objectively quantitated in vivo by the use of spectral imaging. To this end we applied the method on a histamine-induced cutaneous edema model. Apparent concentrations of oxy-hemoglobin, deoxy-hemoglobin, and water were calculated for each pixel of a spectral image stack. These values were used to construct concentration maps for each of these molecules as well as an intensity map of an optical tissue-scattering parameter. The oxy-hemoglobin and the tissue water maps are two-dimensional quantitative representations of the skin areas involved in erythema and edema, respectively. These maps demonstrated characteristics of the wheal-and-flare reaction and their gray-level intensities were dependent on the applied histamine dose. We conclude that spectral imaging can be a valuable noninvasive tool in the study of edema pathology and can be used to monitor the edema reaction in vivo or follow the efficacy of treatments in a clinical setting.     

The incidence of venous thromboembolism in patients undergoing surgery for acute Achilles tendon ruptures

Background

This retrospective analysis was prompted by the authors’ observation of the relatively high incidence of venous thromboembolism (VTE) in the surgical repair of acute Achilles tendon ruptures.

Method

88 patients were treated surgically for an acute Achilles tendon rupture. No prophylactic anticoagulation was given to any patients. The incidence of VTE was then reviewed retrospectively.

Results

Five patients developed symptomatic deep vein thrombosis (5,7%) and one a near-fatal pulmonary embolus (1.1%). There were no major bleeding or cardiovascular adverse events. One patient developed a thrombus of the lesser saphenous vein (1.1%) and there was one superficial sepsis (1.1%). A temporary peroneal nerve palsy occurred in one patient (1.1%). There were two re-ruptures (2.3%).

Conclusion

There is no doubt that thromboprophylaxis must be given to the high risk patient and is also recommended for major orthopaedic surgery. Limited data is available for the use of thromboprophylaxis in foot and ankle surgery. In light of the unacceptably high incidence of venous thromboembolism in this study, the authors suggest that routine venous thromboembolism prophylaxis should be considered for these patients.

Level of evidence

Therapeutic study, Level III (retrospective study).     

The dynamics of pigment reactions of human skin to ultraviolet A radiation

The pigment responses of human skin to broadband UVA radiation (320‐400 nm) occur in three distinct phases. The first phase includes immediate pigment darkening (IPD), the pigment that appears immediately after irradiation. The second phase involves an intermediate step, termed persistent pigment darkening (PPD), which leads to the third phase of neomelanogenesis or delayed tanning (DT). Since DT results from synthesis of new melanin, it persists beyond 5‐7 days. We conducted studies on human subjects to investigate the dynamic responses of the IPD and PPD reactions to broadband UVA radiation at threshold and superthreshold doses. The threshold doses for IPD, PPD, and DT were found to be approximately 1, 11, and 18 J/cm², respectively. The colorimetry ΔL* value corresponding to minimal clinically perceptible pigmentation was found to be 0.8 ± 0.1. IPD appeared immediately and had an associated decay constant of approximately 1.4 minutes. At doses greater than PPD threshold, IPD reaction decayed while PPD developed indicating toward IPD being used as a substrate in the formation of PPD.