Volker Vieth

Structure analysis of high resolution magnetic resonance imaging of the proximal femur: in vitro correlation with biomechanical strength and BMD.

The purpose of this study was to use high resolution magnetic resonance imaging (HR-MRI) combined with structure analysis to investigate the trabecular structure of the human proximal femur and to compare this technique with bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) in the prediction of bone strength in vitro. Thirty-one fresh human proximal femur specimens were examined with HR-MRI using a T1-weighted 3D spinecho-sequence in a coronal plane (voxel size: 0.195 × 0.195 × 0.9 mm and 0.195 × 0.195 × 0.3 mm). In these images structure parameters analogous to standard bone histomorphometry were obtained in a femoral head, neck, and trochanteric region of interest (ROI). In addition, BMD measurements were obtained using DXA and finally, all specimens were tested biomechanically in a materials testing machine, and maximum compressive strength (MCS) was determined. Correlations between BMD and MCS were significant (p <0.01) with R-values up to 0.74. Correlating structure parameters and MCS R-values up to 0.69 (P <0.01) were obtained. Using multivariate regression analysis, combining structure parameters and BMD, improved correlations versus MCS substantially (up to R = 0.93; P <0.01). In conclusion, this study showed that in an experimental setting, structure parameters determined in high resolution MR images of the proximal femur correlated significantly with bone strength. The highest correlations, however, were obtained combining BMD and structure measures.

Risk of recurrence and survival after relapse in patients with Ewing sarcoma.

The prognosis in patients with relapsed Ewing sarcoma is unfavorable. Our investigation identifies factors predicting for the outcome following relapse.

Primary stability in cementless femoral stems: custom-made versus conventional femoral prosthesis

OBJECTIVE To compare a custom-made femoral stem with a conventional cementless stem for initial stability in human femurs. DESIGN The bone-femoral prosthesis interface motion was measured in vitro using displacement transducers. Combined axial and torsional loads simulating single-leg stance, loading were applied. BACKGROUND The custom-made prosthesis is a cementless femoral stem fabricated from the patients CT-reconstruction. To justify its clinical use its design has to be tested regarding his primary stability. METHODS Seven pairs of human cadaveric femurs were used for testing the custom-made prosthesis versus a conventional cementless stem. Subsidence, rotation and interface motion were measured with load cycles up to 2000 N. RESULTS The critical interface motion of 150 microm for the cementless prosthesis was not exceed for both types of prosthesis. The custom-made prosthesis enlarged in its metaphyseal part showed a decrease of dynamic micromotions and rotation behavior in the proximal region compared to the Alloclassic prosthesis stem. CONCLUSIONS The initial stability of the custom-made femoral stem was comparable to that of a conventional femoral stem. RELEVANCE The data set for initial stability justifies the clinical use of a custom-made femoral stem in primary hip replacement. An individualized stem fit into the endosteal cortical bone decrease micromotion.

The value of local treatment in patients with primary, disseminated, multifocal Ewing sarcoma (PDMES)

The value of local treatment in patients with primary, disseminated, multifocal Ewing sarcoma (PDMES) was investigated.

Local Differences in the Trabecular Bone Structure of the Proximal Femur Depicted with High-Spatial-Resolution MR Imaging and Multisection CT

RATIONALE AND OBJECTIVES The authors performed this study to investigate structural variations in the trabecular bone of the proximal femur at high-resolution magnetic resonance (MR) imaging and high-resolution multisection computed tomography (CT). MATERIALS AND METHODS Bone mineral density (BMD) was measured in 36 proximal human femur specimens by using dual x-ray absorptiometry. High-resolution MR imaging was performed at 1.5 T with an in-plane spatial resolution of 0.195 x 0.195 mm and a section thickness of 0.3 and 0.9 mm. Multisection CT was performed with an ultra-high-resolution protocol; images were obtained with an in-plane spatial resolution of 0.25 mm and a section thickness of 1 mm. In a subset of these specimens, micro CT was performed with an isotropic spatial resolution of 30 microm. Identical regions of interest (ROIs) were used to analyze images obtained with MR imaging, multisection CT, and micro CT. Trabecular bone structural parameters were obtained, and the parameters from the individual imaging modalities and BMD were correlated. RESULTS Significant differences concerning the trabecular microarchitecture between the individual ROIs were demonstrated with multisection CT and MR imaging. A number of the correlations between structural parameters derived with multisection CT, MR imaging, micro CT, and BMD measurements were significant. For MR imaging, threshold technique and section thickness had an effect on structural parameters. CONCLUSION Structural parameters obtained in the proximal femur with multisection CT and high-resolution MR imaging show regional differences. These techniques may be useful for depicting the trabecular architecture in the diagnosis of osteoporosis.

High-resolution magnetic resonance imaging of the temporomandibular joint: image quality at 1.5 and 3.0 Tesla in volunteers.

Purpose:To assess the image quality of a high-resolution imaging protocol for the temporomandibular joint (TMJ) at 3.0 T and to compare it with our standard 1.5 T protocol. Materials and Methods:Fifteen volunteers without history of TMJ dysfunction underwent bilateral magnetic resonance imaging (MRI) of the TMJ with the jaw in closed and open position. MRI was performed with using a 1.5 T (standard TMJ coil) and 3.0 T (purpose build phased array coil) MR system (Gyroscan Intera 1.5 T and 3.0 T; Philips Medical Systems, Best, the Netherlands). Imaging protocols consisted of a parasagittal PDw-TSE sequence and a coronal PDw-TSE sequence in closed mouth position and a sagittal PDw-TSE sequence in open mouth position. Acquisition parameters were adjusted for 3.0 T and voxel size was reduced from 0.29 × 0.29 × 3.0 mm (1.5 T) to 0.15 × 0.15 × 1.5 mm (3.0 T). Total examination time (15 minutes) was similar for both systems. Two observers assessed in consensus delineation, image quality, and artifacts of anatomic landmarks (disk, bilaminar zone, capsular attachment, cortical bone) and ranked them qualitatively on a 5-point scale from 1 (optimal) to 5 (nondiagnostic). Disk position and motility was noted. For CNR analysis, signal intensity from disk and retrodiscal tissue was measured. Results:Disk position and mobility was identical at both field strengths. All anatomic landmarks were visualized significantly better at 3.0 T. In particular, the capsular attachment was depicted in more detail. Overall image quality was ranked significantly higher at 3.0 T, whereas artifact score was similar. Quantitative evaluation showed significantly higher CNR for 3.0 T (10.23 vs. 8.08, P < 0.0001). Conclusion:Depiction of the normal anatomy of the TMJ benefits significantly when investing the higher SNR at 3.0 T into better spatial resolution. We anticipate that this advantage of 3.0 T MRI will also permit a more detailed analysis of capsular and disk pathology.

Influence of the examiner’s qualification and sources of error during stage determination of the medial clavicular epiphysis by means of computed tomography

Computed tomography (CT) of the medial clavicular epiphysis has been well established in forensic age estimations of living individuals undergoing criminal proceedings. The present study examines the influence of the examiner’s qualification on the determination of the clavicular ossification stage. Additionally, the most frequent sources of error made during the stage assessment process should be uncovered. To this end, thin-slice CT scans of 1,420 clavicles were evaluated by one inexperienced and two experienced examiners. The latter did the evaluations in consensus. Two classification systems, a five-stage system and a substaging system for the main stages 2 and 3, were used. Prior to three of his six assessment sessions, the inexperienced examiner was specifically taught staging of clavicles. Comparison of the examiners’ results revealed increasing inter- and intraobserver agreements with increasing state of qualification of the inexperienced examiner (from κ= 0.494 to 0.674 and from κ= 0.634 to 0.783, respectively). The attribution of a not-assessable anatomic shape variant to an ossification stage was identified as the most frequent error during stage determination (n= 349), followed by the overlooking of the epiphyseal scar defining stage 4 (n= 144). As to the clavicular substages, classifying substage 3a instead of 3b was found to be the most frequent error (n= 69). The data of this study indicate that κ values must not be considered as objective measures for inter- and intraobserver agreements. Furthermore, a high degree of specific qualification, particularly the knowledge about the diversity of anatomic shape variants, appears to be mandatory and indispensable for reliable evaluation of the medial clavicular epiphysis.

Age estimation in U-20 football players using 3.0 tesla MRI of the clavicle.

BACKGROUND To guarantee equal chances for participants in U-20 football tournaments, it seems desirable to verify the ages given by players with questionable dates of birth. OBJECTIVE To study the potential use of 3.0 tesla MRI of the clavicle in estimating the ages of U-20 football players. METHODS The ossification stage of the medial clavicular epiphyses was evaluated prospectively in 152 male footballers in the age group from 18 to 22 years using 3.0 tesla MRI. RESULTS Average age increased with any higher degree of fusion. The only footballer with full ossification of the medial clavicular epiphyseal plate was 21.2 years old. CONCLUSIONS The presence of a fully ossified clavicular epiphyseal plate appears to provide evidence of completion of the 20th year of life. The results of the pilot study need to be verified in a larger number of cases.

The Diagnostic Imaging of Bone Metastases

BACKGROUND Skeletal metastases are the most common malignant tumor in bone. Certain types of cancer (e.g., of the prostate or breast) are particularly likely to give rise to skeletal metastases, with prevalences of up to 70%. The diagnosis of skeletal metastases has a major impact on the overall treatment strategy and is an important determinant of the course of illness and the quality of life. The goal of diagnostic imaging is to detect skeletal metastases early, whenever they are suspected on the basis of clinical or laboratory findings or in patients who are at high risk. Other important issues include assessment of the risk of fracture and the response to treatment. METHODS This review is based on selected pertinent articles published up to December 2013. RESULTS Projectional radiography (plain films) is still useful for the immediate investigation of symptomatic bone pain and for the assessment of stability. Skeletal scintigraphy, the classic screening test for patients with cancer who do not have bone pain (specificity 81%, sensitivity 86%), has now been supplemented-in some cases, replaced-by other techniques. CT, including lowdose CT, is used to detect changes in bone structure due to metastases of some types of primary tumor (specificity 95%, sensitivity 73%); whole-body MRI, to detect metastases in the bone marrow and extraosseous soft tissues, e.g., metastases compressing the spinal cord (specificity 95%, sensitivity 91%); PET-CT, to detect metabolically active tumors (specificity 97%, sensitivity 90%). CONCLUSION Different imaging modalities are often used in combination to detect bone metastases optimally. Owing to advances in modern tomographic imaging, the current trend is toward whole-body imaging in a single session. The choice of method is based on the clinical situation and the type of primary tumor. Further research should address the impact of these costly and laborintensive imaging methods on treatment strategies and on the course of illness.

Sagittal plane kinematics of fixed- and mobile-bearing total knee replacements

PurposeThe objective of this prospective, randomized, patient- and observer-blinded study was to analyze, in vivo, the knee joint kinematics in the sagittal plane in a patient population that had received either a fixed or a mobile TKA.MethodsThirty-one patients (57 knees) were evaluated by means of fluoroscopy during unloaded flexion and extension against gravity as well as during step up and step down with full weight bearing. In these 31 patients, 22 fixed-bearing TKAs, 16 mobile-bearing TKAs, and 19 natural knee joints were included. Fluoroscopic radiographs were evaluated by measuring the “patella tendon angle” in relation to the knee flexion angle, as a measure of anteroposterior translation, as well as the “kinematic index,” as a measure of reproducibility.ResultsDuring unloaded movement, fluoroscopic analysis did not show a significant difference between both types of prosthesis design and the natural knee. In the weight-bearing movement, both types of TKA designs revealed a more linear patellar tendon angle curve, with a greater angle in extension and in flexion than in the natural knees. In the mobile-bearing group, interindividual deviations from the mean during weight-bearing movements were significantly less than in the fixed-bearing group.ConclusionsNo functional advantage of mobile-bearing TKA over fixed-bearing devices could be found. Both TKA designs showed the typical kinematics of an anterior instability. These results only apply to cruciate retaining mobile-bearing TKA with a bearing that allows both rotation and anteroposterior translation, using a sagittal plane kinematics analysis evaluated by such methodology. A possible influence of less variability of the kinematic pattern on clinical results still needs to be confirmed.Level of evidenceProspective comparative study, Level II.