Imaging decisions (Berlin, Germany)最新文献

Magnetic resonance (MR) techniques have revolutionized the assessment of brain development and injury in the newborn. MR studies at 3 T or above are becoming widespread; however, given the high cost and complexity of high-field MR systems, it is important to assess their benefits and limitations for clinical practice.

MR spectroscopy (MRS) studies at high field carry potential benefits such as improved signal-to-noise ratio (SNR) and chemical shift dispersion compared with 1.5 T. However, safety is a very important consideration as radiofrequency (RF) tissue heating and acoustic noise also increase with field strength. Furthermore, increased chemical-shift dependence of the position of the volume of interest (VOI), shorter transverse and longer longitudinal relaxation times constitute additional challenges.

We describe the first in-vivo, proton MRS studies of newborn human brain at 4.7 T. Nine infants with neonatal encephalopathy, all ventilated and with continuous physiological monitoring, were studied. We used L-FOCI localization, mostly with a VOI centred on the thalami.

The absence of 4.7 T results from healthy infants made it impossible to interpret pathological metabolite peak-area ratios. However, concentration ratios and concentrations should be field-strength independent and interpretable using control values acquired at lower field. Of eight infants with concentration-ratio measurements, seven had low [N-acetylaspartate (NAA)]/[choline (Cho)] and three increased [lactate]/[NAA]. Of the two infants with ‘concentration’ measurements both had low [NAA] and one reduced [creatine].

We used an adult coil and consequent RF power restrictions had repercussions for the minimum magnetization recovery time (TR). A smaller, neonatal coil should improve SNR and, with less RF power, relax TR constraints thereby enabling fuller exploitation of the potential of high-field MRS.

Advances in neuro-imaging techniques, such as MR imaging, have allowed the demonstration of a wide range of subtle pathologies not possible with previous methods. This is particularly true in the case of brain malformations. In this review I will discuss the range of imaging methods available and describe a structural approach to classifying the range of brain malformations. The most common variety of pituitary malformations are also included in this review.

Magnetic resonance (MR) imaging of the neonate can be a difficult procedure especially when most imaging departments are geographically distant to neonatal intensive care units. These vulnerable neonates are often notable to be imaged by MR as they are too sick to transport. MR scanners are expensive pieces of equipment in specialist centres and this limits their availability. Low field strength scanners have a small capital cost and small running costs. This has allowed them to be developed for dedicated neonatal imaging in a few centres. Experience using these scanners is limited but they provide additional information over and above ultrasound imaging and are an ideal method to increase the availability of MR. MR compatible incubators that double as transport incubators reduce the amount of handling the vulnerable neonate is exposed to and maintains the environmental conditions required for the neonate. This makes access to distant MR scanners possible. Fast imaging sequences reduce the overall scanning time and reduce the need for sedation or anaesthesia. These methods allow the vulnerable neonate to be imaged safely whilst providing essential imaging information for optimal clinical management.

Sports injuries may cause traumatic and degenerative injuries at both an amatuer and professional level and are caused by direct athletic gestures or biomechanical modifications triggered by repetitive movements. Because of its particular morphology, the ankle is often involved in these injuries, particularly in soccer, athletics and basketball. The most common pathologies involve sprains, but there may also be osteochondral fractures, impingement syndrome, stress fractures or tendon injuries. There is a complex diagnostic cycle which must include an evaluation of the clinical history, specific information from specialists and diagnostic imaging. Nowadays, there are many and varied methodologies available that vary in sensibility and specificity. The correct diagnostic imaging cycle must be followed, integrating the methodologies in such a way as to obtain the most reliable diagnostic data as possible.

Hip and groin injuries are usually seen with kicking, running and jumping athletic activities. Both recreational and elite athletes can be involved with hip and groin injuries. Although not very common, sports-related injuries of the hip and groin may impose a significant diagnostic dilemma for both the clinicians and the radiologists. Delayed diagnosis and treatment may result in complications, such as permanent disability or premature degenerative joint disease. Plain X-rays are the initial examination although usually unremarkable. Computed tomography can be helpful in certain cases such as tiny avulsion injuries, intraarticular loose bodies and myositis ossificans. Magnetic resonance (MR) imaging of the hip and groin area has proven to be extremely valuable in the diagnosis of radiographically occult osseous abnormalities as well as musculotendinous injuries. MR imaging is helpful in clinically confusing disorders such as stress bone marrow reactions and bursitis. MR imaging following the intraarticular administration of gadolinium is valuable for evaluating the cartilaginous, osteochondral and acetabular labral injuries. The osseous and soft tissue conditions summarized in this article represent those most commonly considered in the differential diagnosis of hip and groin injuries in athletes.

In general, the patient population of the sports physician are highly motivated, competitive athletes, who tend to be under continuous time pressure. Imaging techniques can be very helpful in establishing the correct diagnosis and for choosing the appropriate therapy, monitoring the healing process and evaluating complications. In this chapter the role of imaging is discussed with specific focus on muscle and tendon injuries, stress fractures, shoulder and ankle injuries.

Tendon and muscle lesions appear in manifold forms clinically as well as on magnetic resonance or ultrasound images. Tendinous abnormalities may be classified and staged with respect to their biomechanical role in a kinetic chain by using the concept of the tendon overuse syndrome (TOS). In the first phase, painful functional impairment of movements occurs without any morphological changes. In the second stage, abnormalities of the gliding tissue in the form of bursitis, tendovaginitis or peritendinitis are observed. In the third stage, such lesions are followed by degenerative changes of the tendon itself. Often, they present more clearly than during the early forms of TOS and three types of tendon degeneration can be differentiated: tendinosis at distinct points along the course of the tendon, fibroostosis at the tendon insertion and compression or impingement syndromes. Rupture of fibres following tendinosis may be considered as the last or fourth stage of TOS.