Chemical shift imaging at 4.7 tesla of brown adipose tissue.

In vivo distinction between small deposits of brown adipose tissue (BAT) and surrounding tissues may be difficult. In this article, we propose an experiment paradigm, based on techniques of chemical shift magnetic resonance imaging (CSI), which can improve the methods presently available for the study of BAT. Male rats were examined in an imager-spectrometer equipped with a 4.7 T magnet. Proton spectra of isolated BAT deposits showed that both fat and water protons contributed significantly to the genesis of the magnetic resonance signal. An equivocal definition of BAT deposits was obtained by three (respectively, spin-echo, water-selective, and fat-selective) images. The spin-echo (SE), T1-weighted image provided the best anatomical description of the structures. The images selective for fat-protons displayed the degree of lipid accumulation in each area. The images selective for water-protons provided an internal control of adipose tissue localization. The proposed paradigm allows an unequivocal definition of BAT deposits and appears particularly useful in studies where experimental manipulation (i.e., cold acclimation or drug treatment) produces changes in this issue

Chemical shift imaging at 4.7 tesla of brown adipose tissue

In vivo distinction between small deposits of brown adipose tissue (BAT) and surrounding tissues may be difficult. In this article, we propose an experimental paradigm, based on techniques of chemical shift magnetic resonance imaging (CSI), which can improve the methods presently available for the study of BAT. Male rats were examined in an imager-spectrometer equipped with a 4.7 T magnet. Proton spectra of isolated BAT deposits showed that both fat and water protons contributed significantly to the genesis of the magnetic resonance signal. An unequivocal definition of BAT deposits was obtained by three (respectively, spin-echo, water-selective, and fat-selective) images. The spin-echo (SE), T1-weighted image provided the best anatomical description of the structures. The images selective for fat-protons displayed the degree of lipid accumulation in each area. The images selective for water-protons provided an internal control of adipose tissue localization. The proposed paradigm allows an unequivocal definition of BAT deposits and appears particularly useful in studies where experimental manipulation (i.e., cold acclimation or drug treatment) produces changes in this tissue

Distraction osteogenesis of the Mandible: problems connected with dental movements.

Distraction osteogenesis of the Mandible: problems connected with dental movements. Distraction Osteogenesis(DO) is a techinique that leads to osseus generation and osteosynthesis by means of slow traction applied to the bone and the soft tissues. The present case shows the forward movement of the mandible using the DO in a skeletal class II iperdivergent patient, with a mandibular retrusion. DO provides a slower, and thus more "physiological", solution for skeleton malocclusion than the usual traditional techniques. It is necessary, however, to follow up surgery with an appropriate orthodontic finalization

The Distraction Osteogenesis in Midfacial Hypoplasia

Distraction osteogenesis (DO) can generate new bone in a gap between 2 vascularized bone surfaces in response to application of graduated tensile stress across the bone gap. The authors present the clinical result in a cleft patient with severe maxillary deficiency treated by a rigid external distraction (RED) device. A boy complained of both masticatory and psychological problems because of cleft with severe midfacial retrusion. The treatment aimed to create a well-balanced facial profile, increase maxillary incisal display, create proper overjet and overbite, and align his dentition. By the RED system, the traction is applied to the maxilla through the dentition by an intraoral splint. A complete Le Fort I osteotomy was performed, including pterygomaxillary and septal disjunction, with mobilization. Once osteotomy was completed, the halo portion of the RED device was adjusted for the width of the neurocranium and was rigidly fixed around the head with 2 scalp screws on each side. A well-balanced facial profile and a good alignment of the dentition were obtained. The patients had considerable improvement in his self-esteem. Clinical reports have suggested that maxillary advancements achieved by distraction are more stable than those achieved with orthognathic surgery with a minimal influence on velopharyngeal competence

Comparison of results of scanning electron microscopy and magnetic resonance imaging before and after administration of a radiographic contrast agent in the tendon of the deep digital flexor muscle obtained from horse cadavers

Objective-To analyze the tendon of the deep digital flexor (TDDF) muscle of the forelimb in horses by use of a contrast radiographic agent (gadopentate dimeglumine [Gd-DTPA/Dimeg]) and magnetic resonance imaging (MRI) and to determine the concentration of water protons in the tendons by use of MRI. Sample Population-8 TDDF harvested from the forelimbs of 6 horse cadavers. Procedure-Examinations were performed on the same portion of each tendon. Tendons were examined by use of two techniques: MRI before and after treatment with Gd-DTPA/Dimeg as well as scanning electron microscopy. Results-Tendons did not have detectable signal intensity on MRI before treatment with Gd-DTPA/Dimeg; however, intravascular injection of Gd-DTPA/Dimeg allowed evaluation of the internal structure of the tendons. Scanning electron microscopy images correlated well with images obtained by use of MRI before and after administration of Gd-DTPA/Dimeg. Localized spectra revealed the concentration of water protons in the TDDF. Conclusions and Clinical Relevance-The techniques used in this study provided information about internal organization of the TDDF in horses. Analysis of results revealed that the best technique involved vascular injection of contrast medium. Results of MRI correlated well with results for scanning electron microscopy. After administration of Gd-DTPA/Dimeg, MRI provided additional information about tendon morphologic characteristics. This technique may be of value for examination of tendons in lame horses

Use of magnetic resonance imaging for diagnosis of a spinal tumor in a cat

Magnetic resonance imaging was used to identify a spinal mass at the level of the 6th-7th cervical vertebral body in a cat. The MRI images were most consistent with the presence of an intradural, extramedullary meningioma that was confirmed by subsequent histological examination

Paraparesis caused by vertebral canal leishmaniotic granuloma in a dog

- not available

Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

BACKGROUND: Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI) in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI) at high field intensity (4.7 T). The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle. METHODS: The study was performed in 4-month-old (n = 6) and 20-month-old (n = 6) rats. RESULTS: At MRI examination, the relaxation time T2 of the gastrocnemius muscle showed no significant difference between these two groups. The kinetic of contrast penetration in the tissue showed that in 4-month-old rats the enhancement values of the signal intensity at different time-points were significantly higher than those found in senescent rats. CONCLUSION: The reported finding suggests that there is a modification of the microcirculatory function in skeletal muscle of aged rats. This work also demonstrates that CE-MRI allows for an in vivo quantification of the multiple biological processes involving the skeletal muscle during aging. Therefore, CE-MRI could represent a further tool for the follow up of tissue modification and therapeutic intervention both in patients with sarcopenia and in experimental models of this pathology

Delayed muscle injuries in arterial insufficiency: contrast-enhanced MR imaging and 31P spectroscopy in rats

PURPOSE: To evaluate whether the vascular system resulting from an arteriallesion shows differences in permeability to a tracer with respect to the normalvascular system and whether eventual differences are maintained for long periods.MATERIALS AND METHODS: Permanent ischemia was induced in rats with femoralarterial removal, and magnetic resonance (MR) imaging was performed after 1, 7,14, and 90 days. Gadopentetate dimeglumine was injected, and the kinetics of its penetration in the leg were studied. Phosphorus 31 spectroscopy was performed to determine the bioenergetic characteristics of the gastrocnemius muscle at restand stimulation. Ischemic muscles were then processed for electron microscopy.RESULTS: After ischemia induction, a hyperintense area that progressivelydecreased was present on T2-weighted images. Gadopentetate dimeglumine improvedthe signal intensity of the area. Three months after arterial occlusion, thecontrast-enhanced images still showed microvessels highly permeable to thetracers. Spectroscopic data revealed that 3 months after arterial removal, thebioenergetic reserve of the gastrocnemius muscle was reduced, suggesting that thecontrast-enhanced MR imaging-visible area is functionally relevant.Ultrastructural examination revealed persistent muscle damage and signs ofchronic microangiopathy.CONCLUSION: After ischemia induction, the restitutio ad integrum is not complete,and delayed muscle injuries can result from arterial insufficiency

Leishmania in a Dog

n/