[Postoperative and posttherapeutic changes after primary bone tumors : What's important for radiologists?] / Postoperative und posttherapeutische Veränderungen nach primären Knochentumoren : Was ist wichtig für den Radiologen?

Posttreatment imaging of primary bone tumours represents a diagnostic challenge for radiologists. Depending on the primary bone tumour common radiological procedures, such as radiography, computed tomography (CT), and magnetic resonance imaging (MRI), are employed. Radiography and CT are particularly useful in benign bone tumours and in matrix-forming bone tumours. MRI comes into consideration with malignant tumour recurrence and tumoral soft tissue infiltration. Bone scintigraphy is of superior importance if a primarily multifocal manifestation of bone tumour or metastasizing tumour disease is suspected. Molecular imaging (FDG-PET and hybrid imaging, using CT) are gaining increasing importance in light of monitoring neoadjuvant chemotherapy and detecting recurrent tumour appearance. The current literature shows sensitivity and specificity values for recurrent detection of up to 92% and 93%. Diagnostic accuracy is as high as 95%, thus, exceeding accuracy values for CT (67%) and MRI (86%) by far. Likewise, this is also applicable for the assessment of the neoadjuvant chemotherapy. Moreover, PET-based modalities are able to establish prognostic statements using SUV-threshold values at baseline (especially for Ewing sarcomas). Advanced imaging techniques have made a great diagnostic step forward and have proven to be relevant and reproducible with respect to both relapse detection and treatment assessment. Furthermore, it is not clear whether a higher detection rate of early tumour recurrence will inevitably lead to better outcome and survival.

[Soft tissue tumors : Imaging strategy for local primary diagnostics - manifestation, pearls and pitfalls in MRI]. / Weichteiltumoren : Bildgebungsstrategie in der lokalen Primärdiagnostik - Erscheinungsbild, Pearls und Pitfalls in der MRT.

Only approximately 1% of soft tissue tumors are malignant. Potentially malignant lesions can be recognized by ultrasound and submitted for magnetic resonance imaging (MRI). Radiography can supply valuable additional information. The MRI examination is the imaging reference standard for soft tissue tumors and also serves as local staging modality. Lesions which are indeterminate in MRI, or in which therapy is dependent on histology results, should be biopsied. Referral to a reference center is recommended. The multitude of soft tissue tumor entities are classified according to the World Health Organization (WHO) system (latest version 2013). Some tumors show characteristic locations and MRI morphology. Sarcoma staging by imaging is influenced by the size and site in comparison to the surface fascia. International standards must be adhered to: decisive for the patient is in particular the care by an experienced interdisciplinary tumor team.

Impact of high field (3.0 T) magnetic resonance imaging on diagnosis of osteochondral defects in the ankle joint.

OBJECTIVE: To evaluate high field magnetic resonance (MR) imaging for imaging of osteochondral defects. MATERIALS AND METHODS: Nine osteochondral defects were simulated in three cadaveric talus specimens using a diamond drill. All specimens were examined on a 1.0 T MR unit and a 3.0 T MR unit. A T2-weighted turbo spin-echo (TSE) sequence with a 2 mm slice thickness and a 256 x 256 matrix size was used on both scanners. The visibility of the osteochondral separation and the presence of susceptibility artifacts at the drilling bores were scored on all images. RESULTS: Compared to the 1.0 T MR unit, the protocol on the 3.0 T MR unit allowed a better delineation of the disruption of the articular cartilage and a better demarcation of the subchondral defect. Differences regarding the visualization of the subchondral defect were found to be statistically significant (P<0.05). Differences with regard to susceptibility artifacts at the drilling bores were not statistically significant (P>0.05). The average SNR was higher using 3.0 T MRI (SNR=12), compared to 1.0 T MRI (SNR=7). CONCLUSION: High field MRI enables the acquisition of images with sufficient resolution and higher SNR and has therefore the potential to improve the staging of osteochondral defects.

[Use of contrast agent in high-field MRI (3 T)]. / Kontrastmittelanwendung auf Hochfeld-(3 T-)MRT.

The basic diagnostic efficacy of MR contrast medium in the evaluation of primary brain tumors and its clinical usefulness in the detection of brain metastases with single and cumulative triple-dose was compared using a high-field 3 T MR unit and a 1.5 T MR unit. Additionally, the effect of contrast agent on high-resolution MR venography based on the BOLD effect was evaluated at both field strengths. Tumor-brain contrast after gadodiamide administration, as assessed by means of statistical evaluation of MP-RAGE scans and T1-SE images, was significantly higher at 3 T than at 1.5 T. The subjective assessment of cumulative triple-dose 3 T images obtained the best results in the detection of brain metastases, followed by 1.5 T cumulative triple-dose enhanced images. Due to higher spatial resolution, contrast-enhanced MR venography at 3 T showed more details in and around tumors than at 1.5 T, additionally enhanced by stronger susceptibility weighting and higher signal-to-noise ratio at 3 T. In summary, administration of gadolinium-based contrast agent produces higher contrast between tumor and normal brain at 3 T than at 1.5 T, helps to detect more cerebral metastases at 3 T than at 1.5 T in single and cumulative triple dose, and improves MR venography at 3 T with increase in spatial resolution within the same measurement time, thus providing more detailed information.

MRI of the cartilage.

With the introduction of fat-suppressed gradient-echo and fast spin-echo (FSE) sequences in clinical routine MR visualization of the hyaline articular cartilage is routinely possible in the larger joints. While 3D gradient-echo with fat suppression allows exact depiction of the thickness and surface of cartilage, FSE outlines the normal and abnormal internal structures of the hyaline cartilage; therefore, both sequences seem to be necessary in a standard MRI protocol for cartilage visualization. In diagnostically ambiguous cases, in which important therapeutic decisions are required, direct MR arthrography is the established imaging standard as an add-on procedure. Despite the social impact and prevalence, until recent years there was a paucity of knowledge about the pathogenesis of cartilage damage. With the introduction of high-resolution MRI with powerful surface coils and fat-suppression techniques, visualization of the articular cartilage is now routinely possible in many joints. After a short summary of the anatomy and physiology of the hyaline cartilage, the different MR imaging methods are discussed and recommended standards are suggested.

Pathophysiology and imaging in inflammatory and blastomatous synovial diseases.

Variable pathologies are subsumed under the term "synovial disease", including common pathologies such as rheumatoid arthritis. While formerly radiologists had to rely on conventional radiographs and bone scintigraphy with their inherent problems in visualizing soft tissue, noninvasive imaging of the synovium has recently improved substantially with the technical development of MRI and (Doppler) ultrasound. These imaging modalities allow differentiation of characteristic pathologic features based on a profound knowledge of normal anatomy and pathophysiology.

Changes in lung parenchyma after acute respiratory distress syndrome (ARDS): assessment with high-resolution computed tomography.

The aim of this study was to evaluate the appearance, extent, and distribution of parenchymal changes in the lung after acute respiratory distress syndrome (ARDS) as a function of disease severity and therapeutic procedures. High-resolution computed tomography (HRCT), clinical examination, and lung function tests were performed in 15 patients, 6-10 months after ARDS. The appearance and extent of parenchymal changes were compared with the severity of ARDS, as well as with clinical and therapeutic data. Lung parenchymal changes resembling those found in the presence of pulmonary fibrosis were observed in 13 of 15 patients (87%). The changes were significantly more frequent and more pronounced in the ventral than in the dorsal portions of the lung ( p<0.01). A significant correlation was observed between the extent of lung alterations and the severity of ARDS ( p<0.01), and the duration in which patients had received mechanical ventilation either with a peak inspiratory pressure greater than 30 mmHg ( p<0.05), or with more than 70% oxygen ( p<0.01). Acute respiratory distress syndrome frequently is followed by fibrotic changes in lung parenchyma. The predominantly ventral distribution of these changes indicates that they may be caused by the ventilation regimen and the oxygen therapy rather than by the ARDS.

[Magnetic resonance tomography (MRI) of joint cartilage. Current status of knowledge and new developments]. / Magnetresonanztomographie (MRT) des Gelenkknorpels. Aktueller Wissensstand und neue Entwicklungen.

MRI is the most accurate noninvasive technique available for assessment of normal articular cartilage and cartilage lesions. MRI cannot only provide morphologic information about the area of damage, but can also provide unique insight into the biochemical composition of the articular cartilage. New image processing techniques such as three-dimensional mapping of cartilage thickness will help to establish automated analysis of cartilage loss. Theses techniques are ideally suited for monitoring patients who undergo treatment with new chondroregenerative drugs.

Factor X Frankfurt I: molecular and functional characterization of a hereditary factor X deficiency (Gla+25 to Lys).

A family with hereditary factor X deficiency is presented. One member, a 25-year-old man, showed a mild bleeding tendency. His factor X activity (extrinsic: 56%; intrinsic: 55%; Russell's viper venom: 57%) and his level of circulating factor X antigen (55% of normal) were markedly reduced. Analysis of his factor X gene revealed a single point mutation within exon II resulting in the substitution of +25 Gla (GAA) by Lys (AAA). The mutation was determined by gene analysis to be heterozygous in this patient, his mother and one of his brothers. Clotting assays of factor X purified from the plasma of the index patient revealed an activity of 89% of normal upon activation with Russell's viper venom, 77% of normal in the intrinsic and 81% of normal in the extrinsic coagulation pathway. The mutation responsible for the substitution of Lys for Gla+25 was introduced into an expression plasmid containing a wild type factor X cDNA and expressed in a mammalian cell line. Factor X antigen levels in the cell lysates and in the supernatant were identical in the mutant and wild type constructs. The specific activity of the factor X expressed from the mutant construct was 3% compared with the wild type construct. These data demonstrate that the substitution of Lys for Gla+25 results not only in a reduced level of factor X in the affected family members, but also in a substantial loss of specific factor X activity.