Design and development of a mobile image overlay system for needle interventions

Previously, a static and adjustable image overlay systems were proposed for aiding needle interventions. The system was either fixed to a scanner or mounted over a large articulated counterbalanced arm. Certain drawbacks associated with these systems limited the clinical translation. In order to minimize these limitations, we present the mobile image overlay system with the objective of reduced system weight, smaller dimension, and increased tracking accuracy. The design study includes optimal workspace definition, selection of display device, mirror, and laser source. The laser plane alignment, phantom design, image overlay plane calibration, and system accuracy validation methods are discussed. The virtual image is generated by a tablet device and projected into the patient by using a beamsplitter mirror. The viewbox weight (1.0 kg) was reduced by 8.2 times and image overlay plane tracking precision (0.21 mm, STD = 0.05) was improved by 5 times compared to previous system. The automatic self-calibration of the image overlay plane was achieved in two simple steps and can be done away from patient table. The fiducial registration error of the physical phantom to scanned image volume registration was 1.35 mm (STD = 0.11). The reduced system weight and increased accuracy of optical tracking should enable the system to be hand held by the physician and explore the image volume over the patient for needle interventions.

[Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: a guideline by the working group "Tissue Regeneration" of the German Society of Orthopaedic Surgery and Traumatology (DGOU)]

Autologous chondrocyte transplantation/implantation (ACT/ACI) is an established and recognised procedure for the treatment of localised full-thickness cartilage defects of the knee. The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning potential consequences of primary cartilage lesions and the suitable indication for ACI. Based on current evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than 3-4 cm2; in the case of young and active sports patients at 2.5 cm2. Advanced degenerative joint disease is the single most important contraindication. The review gives a concise overview on important scientific background, the results of clinical studies and discusses advantages and disadvantages of ACI.

Fütterungsbedingte Rehe – Rezidivprophylaxe beim übergewichtigen Pferd

Häufige nutritive Ursachen der Hufrehe sind einerseits die Fermentation von großer Kohlenhydratenmengen im Dickdarm (meist aus fruktanreichem Weidegras oder stärkereichem Kraftfutter) mit resultierender Freisetzung und Absorption von bakteriellen Toxinen und Stoffwechselprodukten sowie andererseits Insulinresistenz als Folge von Übergewicht (equines metabolisches Syndrom). Beide Ursachen können zusammenwirken. Übergewichtige Pferde, die bereits einen Reheschub hatten, müssen daher an Gewicht verlieren, um Rezidiven vorzubeugen. In der Regel lässt sich eine Gewichtsabnahme durch eine Ration erreichen, die überwiegend aus spät geschnittenem Heu, Grassamenstroh oder Heu-Stroh-Gemischen (maximal ein Drittel Stroh) besteht und in Mengen von 1–1,2% des Idealgewichts verabreicht wird. Dabei liegt allerdings das Raufutterangebot unter den zur Befriedigung des Kaubedürfnisses geforderten 1,5% der Körpermasse (KM), was zu Problemen wie Aufnahme von Einstreu, Aggressivität und im Extremfall zu Stereotypien führen kann. Kraftfutter sollte gar nicht angeboten werden. Keinesfalls dürfen stärkereiche durch fettreiche Kraftfutter ersetzt werden. Als Einstreu eignen sich (gebrauchte) Sägespäne. Die Weidegrasaufnahme muss erheblich eingeschränkt werden, bei sehr anfälligen Pferden oder wenig zuverlässigem Management ist auf Weidegang zu verzichten. Supplemente müssen energiearm sein. Sie sollten die in einer solchen Ration fehlenden Mineralstoffe und Vitamine ergänzen, gegebenenfalls auch etwas Protein oder Aminosäuren zuführen. Durch regelmäßige Bewegung (ca. 30 Minuten flotter Trab täglich) kann die Insulinsensitivität verbessert werden. Durch das Bewegungsprogramm lässt sich auch der Konflikt der Raufutterreduktion versus Erfüllung des Kaubedürfnisses abmildern, da es der leicht ansteigende Energieverbrauch ermöglicht, etwas mehr Raufutter zu geben. Ein Gewichtsverlust von 0,5–1% der KM pro Woche ist anzustreben, höhere Gewichtsabnahmen können ein Risiko für Hyperlipämie darstellen. Der Erfolg der Reduktionsdiät sollte regelmäßig mittels Wägung und/oder Messung des Körper-, Hals- oder Brustumfangs (1–2 cm Reduktion der Maße pro Woche) überprüft werden.

[Nutritional laminitis--preventive measures for the obese horse]

Nutrition-induced laminitis is often caused by i) fermentation of large amounts of carbohydrates in the hindgut (usually fructans from grass or starch from cereals), which cause the release and absorption of microbial toxins and ii) insulin resistance induced by being overweight (equine metabolic syndrome). Both causes can act together. Overweight horses with a history of laminitis need to reduce body weight to prevent further incidences of laminitis. Weight reduction occurs normally on a diet of late-cut hay, a hay-straw mixture (maximally one third straw to prevent constipation) or grass seed straw all at 1-1.2% of ideal body weight. However, this roughage allowance does not satisfy the need of horses to chew, for which it requires at least 1.5% of ideal body weight. This may lead to behavioural issues, such as allophagia and aggression, and in extreme cases, stereotypic behaviour. Starch concentrates should not be replaced with high fat concentrates. Used saw dust is recommended for bedding. The intake of grass from a pasture has to be considerably and efficiently reduced. If the horse is extremely prone to laminitis or if stable management is unreliable, abstention from grazing is recommended. Any supplements need to be low in energy, and should supply minerals and vitamins which are deficient in the diet. Some additional protein or amino acids may be beneficial. Regular exercise, such as a daily 30-minute speedy trot, improves insulin sensitivity. Exercise increases energy expenditure to a certain extent, allowing a slight increase in the roughage supply, thus alleviating the conflict between energy reduction and fulfilling the need to chew. Weight loss should be 0.5-1% of body weight per week, while at a higher rate there is a potential risk of hyperlipemia. The effectiveness of the reducing diet should be monitored regularly, either by weighing or measuring body, neck or girth circumference (aiming for a reduction of 1-2 cm per week).

Advanced imaging of skeletal manifestations of systemic mastocytosis

Systemic mastocytosis comprises a group of clonal disorders of the mast cell that most commonly involves the skeletal system. Imaging can be helpful in the detection and characterization of the osseous manifestations of this disease. While radiography and bone scans are frequently used for this assessment, low-dose multidetector computed tomography and magnetic resonance imaging can be more sensitive for the detection of marrow involvement and for the demonstration of the various disease patterns. In this article, we review the pathophysiological and clinical features of systemic mastocytosis, discuss the role of imaging for staging and management, and illustrate the various cross-sectional imaging appearances. Awareness and knowledge of the imaging features of this disorder will increase the accuracy of image interpretation and can contribute important information for management decisions.

Spectrum of magnetic resonance imaging appearances of juvenile temporomandibular joints (TMJ) in non-rheumatic children

BACKGROUND

Temporomandibular joints (TMJ) are frequently involved in children with juvenile idiopathic arthritis (JIA), and gadolinium-enhanced magnetic resonance imaging (MRI) is the only modality for an early diagnosis. However, only very few data exist on the appearance of contrast-enhanced MRI of normal juvenile TMJ.

PURPOSE

To define the spectrum of normal MRI findings of juvenile TMJ, and to assess a possible overlap with findings typical for active synovitis in JIA.

MATERIAL AND METHODS

96 children (192 TMJ), 51 boys and 45 girls with a median age of 7.8 years (range 3-13 years), underwent a head MRI. The presence of autoimmune disease, including JIA, was excluded via chart history, available laboratory findings, and the absence of known typical pathological MRI changes (degree of synovial enhancement, hyperintense signal on T2-weighted images in the synovia or bone marrow, and morphologic changes of the mandibular condyle) of the TMJ affected by JIA.

RESULTS

In 90 (94%) children, the TMJ showed no MRI abnormalities compatible with arthritis. In three children (3%), the only abnormal MRI finding was a small bilateral joint effusion. A further three children (3%) had a mild synovial enhancement seen on both axial and coronal MR planes in one child and only in the axial plane in the other two children. Signal hyperintensity on T2-weighted images and other corresponding characteristics of TMJ inflammation were lacking in all these six patients.

CONCLUSION

The vast majority of juvenile TMJ in non-rheumatic children shows no MRI abnormalities. Exceptions, including a discrete enhancement of the synovial membrane (3%) or small joint effusions (3%), can occur in a minority of patients, but none of them are accompanied by other signs of inflammation or morphological changes of the TMJ.