[Muscular magnetic resonance imaging for evaluation of myopathies in children]

BACKGROUND

Myopathies present with a broad diagnostic spectrum which may ultimately require muscle biopsy. MRI has been established as a non-invasive method in diagnosing adult myopathies; not only does MRI reveal characteristic findings which point in a diagnostic direction, but also aids in determining optimal biopsy sites and controlling therapeutic interventions. Muscle MRI is increasingly finding application to pediatric myopathies, especially dystrophies and myositides. The following paper serves to illustrate the use of MRI using exemplary clinical vignettes.

PATIENTS/METHODS

From 1999 until 2006, 180 children with myopathies of unknown aetiology, ages 10 months to 18 years, were examined with a standardised MRI protocol (axial T1-SE and T2-weighted TIRM sequences). The protocol included imaging of the lower extremities whereas sequences displaying the upper extremities were only acquired in selected patients. Furthermore, intravenous contrast agent was only administered in selected children.

RESULTS

All investigations could be performed without sedation due to an examination time of 12 to 15 minutes. The illustrated cases of limb-girdle muscular dystrophy, Duchenne's muscular dystrophy, dermatomyositis, pyomyositis, and chronic neurogenic disease with secondary myopathy all showed disease-characteristic MRI patterns which substantially helped to reach the ultimate diagnosis.

CONCLUSIONS

Muscle MRI is a non-invasive and effective instrument in helping to diagnose pediatric myopathies of unknown aetiology. It may facilitate muscle biopsy and serves to control therapeutical effects and disease course. Furthermore, muscle MRI may be applicated even to children of less than 4 years of age without sedation.

Three-dimensional computed tomography cephalometric craniofacial analysis: experimental validation in vitro

The development of three-dimensional (3D) cephalometric analysis is essential for the computer-assisted planning of orthognathic surgery. The aim of this study was to transform and adapt Delaire's two-dimensional cephalometric analysis into the third dimension; this transposition was then validated. The comparative advantage of using 3D computed tomography (CT) surface renderings over profile X-rays was analysed. Comparison was made of inter- and intra-observer reproducibility of the cephalometric measurements done on profile X-rays and on 3D CT surface renderings on the same 26 dry skulls. The accuracy was also tested of the measurements done on 3D CT surface renderings (ACRO 3D) in relation to those directly taken on dry skulls with the help of a 3D measuring instrument. Inter- and intra-observer reproducibility proved significantly superior (p<0.0001) following the 3D CT method. There were no significant differences in the accuracy of measurements between the ACRO 3D software and the 3D measuring instrument. The ACRO 3D software was confirmed as being a reliable tool for developing 3D CT cephalometric analyses. Further research may entail clinical validation of the 3D CT craniofacial cephalometric method of analysis.

[Low-dose CT-guided transthoracic lung biopsy for evaluation of non-infectious chronic interstitial lung disease in children]

BACKGROUND

Children with interstitial pneumonitis (IP) of unknown origin often have to undergo open lung biopsy to establish a final diagnosis. Open lung biopsy is an invasive procedure with major potential complications. In the meantime, CT-guided transthoracic lung biopsy (TLB) has become a common diagnostic procedure in adults.

OBJECTIVE

The aim of this study was to retrospectively evaluate the efficacy and radiation exposure of low-dose CT-guided TLB in children with non-infectious IP of unknown origin.

METHODS

Twelve children (7-males, age range: 7 months-15 years) with non-infectious IP of unknown origin and inconclusive clinical tests underwent CT-guided TLB with a 20-gauge biopsy instrument. A low-dose protocol with acquisition of single slices was used on a 16-row CT scanner: 80 kVp, 20 mAs, slice thickness 10 mm. Biopsy specimens were processed by standard histopathological and immunohistochemical techniques and effective doses were individually calculated.

RESULTS

All biopsies were performed without major complications. Two children (17 %) developed a small pneumothorax/pulmonary haemorrhage that resolved spontaneously. A final diagnosis could be established in 9/12 patients (75 %) by CT-guided TLB. In 2 patients (17 %) the results of TLB were inconclusive; however, the clinical suspicion could be disproved. Open lung biopsy was performed in 1 patient (8 %), which demonstrated idiopathic pulmonary fibrosis. On average, the effective dose of CT-guided TLB was 0.78 mSv (0.4 - 1.1 mSv).

CONCLUSION

Low-dose CT-guided TLB can be a helpful method for investigating children with non-infectious IP of unknown origin thus making open lung biopsy unnecessary. Application of a low-dose protocol leads to a significant reduction of radiation exposure in CT-guided TLB.

[Extraskeletal mesenchymal chondrosarcoma: rare differential diagnosis of pleural calcifications]

We report on a 78-year-old male patient with unilateral pleural effusion who underwent multiple diagnostic tests including thoracoscopy without establishing a final diagnosis. In the course of time, the patient developed multiple pleural tumors with calcifications. A CT-guided transthoracic biopsy was performed; the specimen revealed histopathological and immunohistochemical evidence for an extraosseous mesenchymal chondrosarcoma. Besides a short review of the literature, the case is discussed as an extremely rare differential diagnosis of pleural calcifications. To the best of our knowledge, this is the first patient in whom the diagnosis of an extraosseous chondrosarcoma, most likely of the pleura, could be established by CT-guided transthoracic biopsy.

[Aneurysmal bone cysts. First description of the extensive destruction of the upper cervical spine]

Aneurysmal bone cysts are not counted among the classic malignant tumors, although they are destructive locally as blood filled reactive bone lesions. Typically, they are found in the metaphysis of the long bones, while localizations on the spine are rare. A 16-year-old female patient presented with unspecific, progressive neck pain which had been present for half a year. The initial x-ray showed no noticeable pathology whatsoever. Subsequently, the complete destruction of the first cervical vertebrae was found. The tumor had completely infiltrated and completely surrounded the spinal chord. A combined approach was used as therapy: resection of the dorsal tumor portion with occipitocervical spondylodesis (C0-C4) and postoperative radiation of the remaining ventral portions. Currently, the patient is free of complaints and recurrence. The differential diagnosis of an aneurysmal bone cyst should also be considered in cases of unspecific cervical vertebral complaints in adolescents that are not otherwise explainable.

Einschätzung der Strahlenbelastung radiologischer Thorax-Verfahren: Was ist Nichtradiologen bekannt?

PURPOSE

Assessment of the knowledge of non-radiological physicians concerning radiation exposure during radiological procedures on the thorax.

MATERIAL AND METHODS

124 non-radiological physicians from the departments of surgery, internal medicine, anesthesiology, and neurology at a university hospital were questioned during a four-week period using a standardized questionnaire as to the effective dose (ED) of different radiological procedures on the thorax. The interviewees were asked to estimate the ED of chest X-rays and CT examinations and to compare these with the ED of other radiological methods. Length of professional experience, field of clinical training, and hierarchical position were also documented. The T-test and chi-square test were used for statistical analysis.

RESULTS

119/124 (96.0 %) physicians with an average work experience of 8.2 years (0.3-32 years) were willing to participate. 47/119 (39.5 %) correctly estimated the ED of conventional chest X-ray (0.01-0.1 mSv), and 40/119 (33.6 %) correctly gauged the ED of adult chest CT (1-10 mSv). The ED of cardiac CT and pediatric chest CT without dose reduction (10-100 mSv) were correctly judged by 31/119 (26.1 %) and 32/119 (26.9 %), respectively. The correct ratio of the ED of chest X-ray to that of chest CT (factor 100-1000) was given by 28/119 (23.5 %), while 86/119 (72.3 %) underestimated the ratio. 50/119 (42.0 %) and 35/119 (29.4 %) correctly stated that the ED of pediatric chest CT without dose reduction and that of cardiac CT are greater than that of adult chest CT. 24/119 (20.2 %) and 10/119 (8.4 %) thought that the ED of low-dose chest CT is smaller than that of chest X-ray or chest MRI, respectively. The length of professional experience, field of clinical training, and hierarchical position of the participants did not have a significant influence on the test results.

CONCLUSION

Correct estimation of the ED of radiological chest examinations, especially that of CT examinations with a high ED, poses substantial difficulties for non-radiologists regardless of the length of professional experience and field of clinical training. In light of the increase in ordered radiological exams, targeted adaptation of medical school teaching content and promotion of pertinent continuing radiological education seem pressing.

Low-density lipoprotein receptor-mediated endocytosis of PEGylated nanoparticles in rat brain endothelial cells

Poly(methoxypolyethyleneglycol cyanoacrylate-co-hexadecylcyanoacrylate) (PEG-PHDCA) nanoparticles have demonstrated their capacity to diffuse through the blood-brain barrier after intravenous administration. However, the mechanism of transport of these nanoparticles into brain has not yet been clearly elucidated. The development of a model of rat brain endothelial cells (RBEC) in culture has allowed investigations into this mechanism. A study of the intracellular trafficking of nanoparticles by cell fractionation and confocal microscopy showed that nanoparticles are internalized by the endocytic pathway. Inhibition of the caveolae-mediated pathway by preincubation with filipin and nystatin did not modify the cellular uptake of the nanoparticles. In contrast, chlorpromazine and NaN(3) pretreatment, which interferes with clathrin and energy-dependent endocytosis, caused a significant decrease of nanoparticle internalization. Furthermore, cellular uptake experiments with nanoparticles preincubated with apolipoprotein E and blocking of low-density lipoprotein receptors (LDLR) clearly suggested that the LDLR-mediated pathway was involved in the endocytosis of PEGPHDCA nanoparticles by RBEC.

[Oblique osteotomy for post-traumatic fibula incongruity]

BACKGROUND

Injuries of the ankle joint are common and, considering that this joint is highly mechanically stressed, it seems obvious that therapy requires restoring the joint to a physiological, anatomically functional unit. In case of post-traumatic shortening, rotation and talar tilt arthritis may result because of the changed biomechanics. Before this occurs, typical clinical symptoms are recurrent swelling, pain, and limited range of motion, together resulting in reduced mobility and quality of life. With prompt indication and revision lengthening the lateral ankle and thus restoring joint congruity, patient complaints are significantly reduced and the development of advanced arthritis can be avoided.

PATIENTS AND METHODS

Within a period of 7 years, 16 patients with post-traumatic shortening of the fibula were treated with oblique osteotomy and lengthening of the fibula at our department. The mean time between trauma and reconstructive surgery was 10 months, and the median follow-up period to clinic and radiological examination was 3.7 years.

RESULTS AND CONCLUSION

Comparison of results before and after correction showed significant subjective improvements, and the development or continuation of post-traumatic arthritis could be hindered, of critical importance to which is prompt indication for operative joint correction, because clinical symptoms of advanced osteoarthritis of the ankle joint cannot be expected to improve.

Species sympatry and horizontal transfers of Mariner transposons in marine crustacean genomes

Mariner-like elements (MLEs) have been widely detected in terrestrial species. The first complete MLE isolated from a marine invertebrate was detected in the genome of the hydrothermal crab Bythograea thermydron by Halaimia-Toumi et al. [Halaimia-Toumi, N., Casse, N., Demattei, M.V., Renault, S., Pradier, E., Bigot, Y., Laulier, M., 2004. The GC-rich transposon Bytmar1 from the deep-sea hydrothermal crab, Bythograea thermydron, may encode three transposase isoforms from a single ORF. J. Mol. Evol. 59, 747-760] and called Bytmar1. Here, we report the isolation of three new Bytmar1 relatives from the genomes of one hydrothermal amphipod Ventiella sulfuris (Vensmar1) and two coastal crustacea, Maia brachydactila (Maibmar1) and Cancer pagurus (Canpmar1). Like Bytmar1, these MLEs have an unusually high GC content, a high CpG ratio, and a low TpA ratio. Their consensus sequence encodes a transposase that is preceded by an N-flag, as in Bytmar1, which could be a marine feature. Only one of the 19 clones obtained, Vensmar1.3, encoded for a full-length transposase. The phylogenetic analyses revealed that all these Bytmar1-related elements can be differentiated into two clusters, corresponding to the coastal or hydrothermal origin of their hosts. They also confirmed that the irritans sub-family comprises at least four lineages that seem to depend on the taxonomical position and habitat of their hosts. Finally, we observed that elements coding for two potentially complete transposases exhibiting 99.5% similarity, Bytmar1.11 and Vensmar1.3, were present in the genome of two distantly related hydrothermal crustacea, one Amphipod and one Decapod. The hypothesis of horizontal transfers is discussed in the light of the sequence similarities observed.

Polymeric nano/microcapsules of liquid perfluorocarbons for ultrasonic imaging: physical characterization

Ultrasonic imaging is a widely available, noninvasive, and cost-effective diagnostic modality, but vessels smaller than 200 mum in diameter are impossible to visualize. Commercial ultrasound contrast agents (UCAs), consisting of encapsulated gas microbubbles injected intravenously, enable only a qualitative visualization of the microvascularization for a short period of time since they are rather unstable. In a strategy to develop more stable UCAs, we designed a process to obtain nano/microcapsules with a single core of liquid perfluorocarbons within a biodegradable polymeric shell of homogeneous thickness. The polymer shell should improve the stability of the capsules as compared to UCAs stabilized by a monomolecular layer, while the acoustic impedance of the perfluorocarbons should ensure their echogenicity. These capsules have been optimized to encapsulate several liquid perfluorocarbons: perfluorohexane, perfluorodecalin, and perfluorooctyl bromide. The system is rather versatile: the mean size of the capsules can be adjusted between 70 nm and 25 microm and the thickness-to-radius ratio (T/R) can be easily modulated by simply modifying the polymer-to-perfluorocarbon ratio. T/R does not depend on the size of the capsules and is between 0.2 and 0.6. The dependence of the echogenic properties of the capsules with their size and their T/R has yet to be studied experimentally before this system can be evaluated in vivo.

Functional interaction between Rh proteins and the spectrin-based skeleton in erythroid and epithelial cells

We summarize the different experimental approaches which provide evidence that direct interaction of Rh and RhAG to ankyrin-R constitutes, together with the AE-1 (Band 3)-ankyrin-protein 4.2 and GPC-protein 4.1-p55 complexes, another major anchoring site between the red cell membrane bilayer and the underlying spectrin-based skeleton. The observations that some residues of the ankyrin binding site are mutated in Rh and RhAG proteins from some weak D and Rh(null) variants, respectively, suggest that the Rh-RhAG/ankyrin-R interaction plays a crucial role in the biosynthesis and/or the stability of the Rh complex in the red cell membrane. Similarly, binding to ankyrin G is required for cell surface expression of the non-erythroid member of the Rh protein family, RhBG, at the basolateral membrane domain of polarized epithelial cells. The next challenge will be to determine whether binding to the membrane skeleton may be critical for the emerging ammonium transport function of Rh proteins in erythroid and non-erythroid cells.

Mediastinale Metastase eines tubaren Chorionkarzinoms nach ektoper Schwangerschaft als seltene Ursache thorakaler Schmerzen

We report on a 26-year old female patient with thoracic pain and dyspnea, in whom a large tumorous mass in the anterior mediastinum with a pleural effusion was diagnosed by computed tomography and magnetic resonance imaging. After rapid progression of tumor growth and detection of malignant cells within the pleural effusion operative intervention including resection of the tumor was performed. Histologic examination of the tumor revealed the typical morphology of a large mediastinal choriocarcinoma. The excessively high hCG-levels returned to normal values post-operatively. A thorough history making revealed an ectopic pregnancy which had made unilateral salpingectomy necessary. Although primary histologic examination of the tubarian tissue had shown no malignancy, a secondary look revealed a choriocarcinoma with identical histological features compared to the mediastinal tumor. Thus, final diagnosis of a mediastinal metastasis of a tubarian choriocarcinoma in ectopic pregnancy was made. We discuss this extremely rare disease and provide a short overview of the literature.