Elastography in musculoskeletal imaging: A tool or a toy?

Elastography is a novel imaging technique based on ultrasound that evaluates the deformability of tissues to help characterize lesions. It is widely used and has been validated in many tissues (e.g., liver, breast, thyroid). It is also used in the study of musculoskeletal disease. Although the use of elastography in musculoskeletal radiology is limited by the variability and heterogeneity of tissues, it is a very promising technique. In this article, we aim to review the usefulness, possible indications, limitations, and future perspectives of this technique in musculoskeletal radiology.

Cardiac sympathetic innervation assessed with (123)I-MIBG retains prognostic utility in diabetic patients with severe left ventricular dysfunction evaluated for primary prevention implantable cardioverter-defibrillator.

BACKGROUND: Scintigraphy with iodine-123-metaiodobenzylguanidine ((123)I-MIBG) is a non-invasive tool for the assessment of cardiac sympathetic innervation (CSI) that has proven to be an independent predictor of survival. Recent studies have shown that diabetic patients with heart failure (HF) have a higher deterioration in CSI. It is unknown if (123)I-MIBG has the same predictive value for diabetic and non-diabetic patients with advanced HF. An analysis is performed to determine whether CSI with (123)I-MIBG retains prognostic utility in diabetic patients with HF, evaluated for a primary prevention implantable cardioverter-defibrillator (ICD). MATERIAL AND METHODS: Seventy-eight consecutive HF patients (48 diabetic) evaluated for primary prevention ICD implantation were prospectively enrolled and underwent (123)I-MIBG to assess CSI (heart-to-mediastinum ratio - HMR). A Cox proportional hazards multivariate analysis was used to determine the influence of (123)I-MIBG images for prediction of cardiac events in both diabetic and non-diabetic patients. The primary end-point was a composite of arrhythmic event, cardiac death, or admission due to HF. RESULTS: During a mean follow-up of 19.5 [9.3-29.3] months, the primary end-point occurred in 24 (31%) patients. Late HMR was significantly lower in diabetic patients (1.30 vs. 1.41, p=0.014). Late HMR≤1.30 was an independent predictor of cardiac events in diabetic (hazard ratio 4.53; p=0.012) and non-diabetic patients (hazard ratio 12.31; p=0.023). CONCLUSIONS: Diabetic patients with HF evaluated for primary prevention ICD show a higher deterioration in CSI than non-diabetics; nevertheless (123)I-MIBG imaging retained prognostic utility for both diabetic and non-diabetic patients.

[Congenital nasal pyriform aperture stenosis]. / Estenosis congénita del orificio piriforme.

Congenital nasal pyriform aperture stenosis (CNPAS) is an unusual cause of upper respiratory obstruction in neonates and infants. The diagnosis is made with Computed Tomography (CT) of nasal cavity when maximum transverse diameter of the pyriform aperture is less than 11 mm. We present a patient with breathing difficulty since birth. The diagnosis of CNPAS was made after a CT examination of the nasal cavity. We also discuss typically associated abnormalities.

[The role of MRI in congenital cystic lesions in the pelvis: a case of uterus didelphys with double vagina, hematocolpos, and ipsilateral renal agenesis.]. / Lesión quística congénita en la pelvis: un caso de útero didelfo con doble vagina, hematocolpos y agenesia renal ipsilateral: papel de la resonancia magnética.

We report a case of uterus didelphys with blind hemivagina and ipsilateral renal agenesis. This is an uncommon anomaly of the development of the Mullerian ducts in which a defect in one of the Wolffian ducts leads to failed induction in kidney formation and in the fusion of the Mullerian ducts. MRI plays a decisive role in the diagnosis and characterization of the malformation.

[Holoprosencephaly. Role of magnetic resonance imaging in prenatal diagnosis]. / Holoprosencefalia. Papel de la resonancia magnética en el diagnóstico prenatal.

We presented a case affected of trisomía 13 and fetal malformations. Prenatal sonography and magnetic resonance imaging were performed. The fetus suffered semilobar holoprosencephaly, craniofacial malformations and tetralogy of Fallot. A review of sonographics and magnetic resonance findings is presented emphasizing the role of magnetic resonance as a complementary imaging technique when sonography has diagnostic limitations.

Advanced correlation functionals: application to bulk materials and localized systems.

Time-dependent density functional theory (TDDFT) is an efficient method to evaluate excited-state properties of electron systems. However, it is not so well-known that it also provides a very accurate prescription to obtain correlation energies by using the so-called adiabatic connection fluctuation dissipation theorem (ACFDT). In this paper we present a detailed study of the ACFDT performance in bulk solids and jellium clusters. These results confirm the reliability of the ACFDT scheme and pave the way to future applications where standard implementations of the Kohn-Sham density functional theory dramatically fail, in particular to weakly bound systems and van der Waals complexes.

Self-consistent density functional calculation of the image potential at a metal surface.

It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z(0)), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z(0), and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

[Optic nerve hypoplasia associated to ectopic neurohypophysis]. / Hipoplasia del nervio optico asociada a neurohipófisis ectópica.

Hypoplasia of the optic nerve is a rare congenital anomaly of unknown etiology that is a frequent cause of blindness in children. It can present in isolation or associated to other malformations of the central nervous system. Magnetic resonance is the technique of choice for the study of this condition; it enables both the hypoplasia of the nerve and the possible associated malformations to be demonstrated. We present a case of optic nerve hypoplasia associated to ectopic neurohypophysis.

First-principles description of correlation effects in layered materials.

We present a first-principles description of anisotropic materials characterized by having both weak (dispersionlike) and strong covalent bonds, based on the adiabatic-connection fluctuation-dissipation theorem with density functional theory. For hexagonal boron nitride the in-plane and out-of-plane bonding as well as vibrational dynamics are well described both at equilibrium and when the layers are pulled apart. Bonding in covalent and ionic solids is also described. The formalism allows us to ping down the deficiencies of common exchange-correlation functionals and provides insight toward the inclusion of dispersion interactions into the correlation functional.

Many-body GW calculations of ground-state properties: quasi-2D electron systems and van der Waals forces.

We present GW many-body results for ground-state properties of two simple but very distinct families of inhomogeneous systems in which traditional implementations of density-functional theory (DFT) fail drastically. The GW approach gives notably better results than the well-known random-phase approximation, at a similar computational cost. These results establish GW as a superior alternative to standard DFT schemes without the expensive numerical effort required by quantum Monte Carlo simulations.