Secuencia de disparo único eco de gradiente en fase y fase opuesta con preparación de la magnetización: descripción y optimización de la técnica con equipo de 1,5 T

Purpose

To implement in-phase and out-of-phase (IP/OP) techniques with Magnetization-Prepared Gradient Recalled Echo (MP-GRE) and to evaluate the feasibility and diagnostic image quality among pre and post-optimized MP-GRE sequences, including patients unable to cooperate with breath-hold requirements.

Materials and methods

Institutional review board approval with waiver of informed consent was obtained for this HIPAA-compliant retrospective study. Two groups of patients were included in the study, before and after optimization of MP-GRE parameters, with seventy-three (24 noncooperative/49 cooperative) and sixty-four (22 noncooperative/42 cooperative) consecutive patients, respectively. The motion-insensitive sequence used in this study was a single-shot 2D MP-GRE. Two radiologists qualitatively evaluated the sequences to identify the presence of phase cancellation artifact in OP images and to determine image quality, extent of artifacts (respiratory ghosting, bounce-point artifact, spatial misregistration and pixel graininess) and lesion conspicuity on the various sequences. The ability to visually detect liver steatosis and fatty adrenal adenomas was evaluated. Qualitative analyses were compared using the Wilcoxon and Mann-Whitney tests.

Results

There were statistically significant differences between all MP-GRE sequences concerning phase cancellation artifact (P<.0001) which was present in MP-GRE OP sequences and negligible to absent in the pre (IP₁) and post-optimized (IP₂) MP-GRE IP sequences, respectively, in all patients.Bounce point artifacts were significantly more pronounced in MP-GRE IP₁ (P<.0001). Spatial misregistration was slightly more prominent in noncooperative patients with MP-GRE IP₂ (P=.0027). MP-GRE OP and MP-GRE IP₂ showed significantly higher overall image quality (P<.0001).MP-GRE sequences subjectively identified hepatic steatosis (n=20) and adrenal adenomas (n=5) based on signal loss from IP to OP sequence.

Conclusion

Single shot IP/OP MP-GRE is feasible and allows motion resistant imaging with adequate diagnostic image quality. This technique is able to provide IP and OP information in patients unable to suspend respiration.     

El radiodiagnóstico ante la violencia de género: un tema de actualidad a tener en cuenta

Domestic violence is currently an issue of great political and social importance. The real incidence of domestic violence is difficult to determine due to the environment where it takes place and the reluctance of victims to report abuse. On the other hand, all types of violence represent an important public health problem.     

Reproducibilidad y exactitud en la cuantificación morfométrica y mecánica del hueso trabecular a partir de imágenes de resonancia magnética de Tesla

Objective

We used an animal model to analyze the reproducibility and accuracy of certain biomarkers of bone image quality in comparison to a gold standard of computed microtomography (μCT).

Material and methods

We used magnetic resonance (MR) imaging and μCT to study the metaphyses of 5 sheep tibiae. The MR images (3 Teslas) were acquired with a T1-weighted gradient echo sequence and an isotropic spatial resolution of 180 μm. The μCT images were acquired using a scanner with a spatial resolution of 7.5 μm isotropic voxels. In the preparation of the images, we applied equalization, interpolation, and thresholding algorithms. In the quantitative analysis, we calculated the percentage of bone volume (BV/TV), the trabecular thickness (Tb.Th), the trabecular separation (Tb.Sp), the trabecular index (Tb.N), the 2 D fractal dimension (D^2D), the 3 D fractal dimension (D^3D), and the elastic module in the three spatial directions (Ex, Ey and Ez).

Results

The morphometric and mechanical quantification of trabecular bone by MR was very reproducible, with percentages of variation below 9% for all the parameters. Its accuracy compared to the gold standard (μCT) was high, with errors less than 15% for BV/TV, D^2D, D^3D, and E_appx, E_appy and E_appz.

Conclusions

Our experimental results in animals confirm that the parameters of BV/TV, D^2D, D^3D, and E_appx, E_appy and E_appz obtained by MR have excellent reproducibility and accuracy and can be used as imaging biomarkers for the quality of trabecular bone.     

Extravasación de medios de contraste intravenosos en el sitio de la punción: Protocolo de actuación

The incidence of contrast medium extravasation at the venipuncture site has increased with the generalized use of automatic injectors. Most extravasations only cause slight edema and erythema. Nevertheless, in some cases extravasation can result in severe skin lesions or even in compartment syndrome. Lesions caused by extravasation usually resolve spontaneously with conservative treatment. Although the complications of extravasation are well known, institutional protocols are normally lacking and the criteria for taking action and the type of treatment, whether based on the literature or personal preferences, tend to vary. In this article, we review the incidence, risk factors, clinical manifestations, and options for preventing and treating contrast medium extravasation in soft tissues. Finally, we present the protocol we use to manage extravasation at our hospital.     

Síndrome de aorta media: presentación de tres casos pediátricos

The middle aortic syndrome (MAS) is caused by stenosis of the abdominal aorta, often accompanied by concomitant stenosis of the renal or visceral arteries. Although MAS is uncommon (0.5-2%), it is an important cause of hypertension in children and adolescents. It is thought to originate in a failure of the two dorsal aortas to fuse during embryological development, and a high percentage of cases are idiopathic. MAS affects the segment of the aorta between the renal arteries in 54% of cases. Clinically, it courses with symptomatic or asymptomatic arterial hypertension. On physical examination, findings include an abdominal bruit, diminished or absent femoral pulses, and a difference between the arterial pressure of the upper and lower limbs.     

La elastografía: una nueva aplicación de la ecografía. ¿Cuál es su utilidad clínica?

Sonoelastography combines elastography and B mode ultrasonography to show parameters related to the structural organization of tissues in real time. Thus, this noninvasive technique shows us the mechanical characteristics of each tissue. The different elastography techniques (qualitative and quantitative, in ultrasonography or magnetic resonance imaging) are based on the hypothesis that soft tissues are more deformable than stiff tissues and that these differences can be captured in images. Elastography adds a new perspective to conventional ultrasonography: it reflects the stiffness of the tissues, and this information, together with the anatomic information from B mode imaging and the vascular information from Doppler, is key for the diagnosis.