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Biomedical subjects

Axel Stäbler

Publications and source records attributed to Axel Stäbler.

9 recordsLinked to original sources
PubMed2005

Diagnosis of osteoporosis: visual assessment on conventional versus digital radiographs.

In many radiological departments conventional radiography has been replaced by digital radiography. Therefore, the purpose of this study was to analyze the visual detection of osteopenia/osteoporosis with both digital and conventional radiographs. In 286 patients we retrospectively evaluated radiographs of the lumbar spine in two planes. One hundred twenty-eight patients had conventional and 158 patients had digital radiographs. Patients with pre-existing vertebral fractures were excluded. Four experienced musculoskeletal radiologists blinded to the values of DXA and to the patients' ages assessed independently from each other whether the bone density of the lumbar spines was normal or decreased. The results of dual X-ray absorptiometry served as the standard of reference. The threshold value for the diagnosis of osteopenia was a T-score less than -1 SD according to the WHO classification of osteoporosis. Sensitivity/specificity was 86%/36% for conventional and 72%/47% for digital radiographs. The overall diagnostic accuracy was 68% for conventional and 64% for digital radiographs. Eighty percent of the patients with osteopenia and 96% of the patients with osteoporosis were correctly assessed as true positive on conventional radiographs and 65% (osteopenia) and 82% (osteoporosis) on digital radiographs. Interobserver agreement was markedly lower for digital (35%) than for conventional radiographs (73%). However, the differences were not statistically significant. There is no major difference in diagnostic accuracy in the assessment of osteopenia/osteoporosis using digital and conventional radiographs, respectively. However, the high interobserver variance on digital radiographs indicates that visual assessment of osteoporosis/osteopenia is problematic, which may be due to image processing and postprocessing algorithms that manipulate the visual aspect of bone density.

Absorptiometry, Photon↗
PubMed2004

Quantification of C2 cervical spine rotatory fixation by X-ray, MRI and CT.

Atlanto-axial rotatory displacement is known to be a cause of childhood torticollis and may as well be responsible for chronic neck pain after rear-end automobile collisions. The objective was to determine whether quantification of C2 malrotation is possible by plain radiographs in comparison to CT as the golden standard. MR imaging was evaluated as to whether it was of equal value in the detection of bony landmarks. C2 vertebra of five human cadaveric cervical spine specimens, ligamentously intact, were rotated using a Steinmann pin in steps of 5 degrees up to 15 degrees right and 15 degrees left. Plain radiographs, CT and MRI images were taken in each rotational step. Data were analyzed for quantification of C2 rotation by three independent examiners. A rotation of 5 degrees led to a spinous process deviation (SPD) from the midline of 3 mm as measured on an a.p. plain radiograph. A coefficient of rotation was calculated (1.62 degrees mm(-1)). Data analyzed by three examiners revealed a small coefficient of variation (0.03). MRI and CT measurements showed comparable results for the quantification of rotation; however, in both techniques the 15 degrees rotation was underestimated. Quantification of upper cervical spine malrotation was possible on plain radiographs using the SPD and a rotation coefficient. MRI and CT were equally successful in the assessment of C2 malrotation.

Adult↗
PubMed2003

Diagnosis of acute fractures of the extremities: comparison of low-field MRI and conventional radiography.

The aim of this study was to compare low-field MRI (0.2 T) and conventional radiography for the detection of acute fractures of the distal part of the extremities. X-ray and MRI examinations of 78 (41 fractures, 37 without fracture) patients with the clinical suspicion of an acute fracture in the distal part of the extremities were compared. Four experienced radiologists, two for each of the two modalities, independently analyzed the images. Interobserver variability and receiver operating characteristic (ROC) analysis for both methods were established. The MRI and conventional radiography revealed an accuracy of 81.4 and of 79.5%, respectively, in the detection of acute fractures. The diagnostic accuracy of MRI to detect fractures in the hand and forefoot proved to be significantly inferior to conventional X-ray examinations. On the other hand, MRI achieved a better accuracy for the examination of bones near a large joint. The interobserver variability for both methods was rated as moderate. In ROC analysis both methods were rated as good. There was no statistical difference of the accuracy between low-field MRI and conventional radiography in the detection of acute fractures of the distal part of the extremities. Consequently, a routine use of low-field MRI as an alternative to conventional radiography to diagnose acute fractures of the extremities seems not to be justified.

Adult↗
PubMed2003

Morphology and topography of intraosseous ganglion cysts in the carpus: an anatomic, histopathologic, and magnetic resonance imaging correlation study.

PURPOSE: To assess the morphology, topography, frequency, and etiology of intraosseous carpal ganglions. METHOD: Two hundred and eighty formalin fixed cadaveric wrists (mean age 80.3 +/- 9.7 years, range 40 to 101 years) were radiographed. Fifty specimens suspicious for cyst-like bone lesions underwent magnetic resonance imaging (T1w and proton density-fat-saturated images, 1.5T). Dissection, articular surface assessment, and histological examination were performed. Cystic lesions with adjacent destruction of the hyaline cartilage were classified as degenerative and were excluded. RESULTS: In 27 of the 50 specimens, 48 ganglion cysts (GC) were found. Prevalence of GC was 9.6%. Of 48 intraosseous carpal GC, 41 (85%) were in a peripheral location; 27/48 (56%) were located at the palmar carpus. GC had a macroscopic and microscopic relationship to the insertion of degenerated ligaments. They developed near longitudinally orientated bone surfaces, which serve as insertion for ligaments and are exposed to tension loading. CONCLUSIONS: Unlike degenerative cysts, ganglion cysts do not erode the hyaline articular cartilage and almost always have a continuity with the capsular ligaments. Intraosseous carpal ganglion cysts are probably the result of mucoid degeneration of adjacent ligaments.

Adult↗
PubMed2003

Inter and intraobserver variability in DePalma's classification of shoulder calcific tendinitis.

OBJECTIVE: To determine the intraobserver reproducibility and interobserver reliability of DePalma and Kruper's classification of calcific tendinitis of the rotator cuff. The result of this classification influences the choice of therapeutic procedures in patients with symptomatic calcific tendinitis. METHODS: Plain anteroposterior radiographs of shoulders from 100 patients with symptomatic calcified deposits of the rotator cuff were classified according to the criteria of DePalma and Kruper by 6 independent observers at 2 different time points within 4 months. The kappa values of intraobserver reproducibility and interobserver reliability were calculated. RESULTS: Kappa values of intraobserver reproducibility had a mean of 0.487 (SD 0.094); kappa values of interobserver reliability were 0.234 for the first test and 0.273 for the second test. CONCLUSION: Determination of intraobserver reproducibility gave satisfactory to sufficient results and interobserver reliability was satisfactory for both tests indicating that studies based on the classification of DePalma and Kruper should be interpreted cautiously.

Adult↗
PubMed2002

Magnetic resonance imaging as a supplement for the clinical staging system of Durie and Salmon?

BACKGROUND: This study evaluated the prognostic value of a three-grade staging system of spinal involvement using magnetic resonance imaging (MRI) in patients with multiple myeloma and determined its usefulness as an independent parameter in the staging system of Durie and Salmon. METHODS: Seventy-seven previously untreated patients with multiple myeloma underwent MRI of the thoracic and lumbar spine with unenhanced T1-weighted spin echo and short-tau inversion time inversion recovery sequences. The patients were evaluated according to their infiltration patterns and the extent of bone marrow involvement was staged using a three-grade scale: Stage I, no focal or diffuse infiltration; Stage II, 1-10 foci or mild diffuse infiltration; Stage III, more than 10 foci or strong diffuse infiltration. RESULTS: The infiltration patterns had no significant effect on survival. Of 77 patients, 25 would have been understaged using the standard staging system of Durie and Salmon without the findings of MRI and 8 patients would have been understaged if the staging was based only on MRI. The combination of the staging system of Durie and Salmon and MRI was highly significant with respect to survival (P < 0.0001, log rank analysis). MRI staging I-III was independent of the staging system of Durie and Salmon (Cox regression model). CONCLUSIONS: A three-grade staging of spinal MRI provides a significant prognostic tool for patients with multiple myeloma. The authors propose including it in the staging system of Durie and Salmon.

Aged↗
PubMed2002

Acute osteoporotic and neoplastic vertebral compression fractures: fluid sign at MR imaging.

PURPOSE: To evaluate the occurrence, location, and shape of the fluid sign in acute osteoporotic and neoplastic vertebral compression fractures at magnetic resonance (MR) imaging. MATERIALS AND METHODS: The study group comprised 87 consecutive patients with acute vertebral compression fractures due to osteoporotic (n = 52) or neoplastic (n = 35) infiltration. The MR imaging protocol included nonenhanced T1-weighted spin-echo and short inversion time inversion-recovery sequences and a 1.5-T system. Readers blinded to the outcome documented the occurrence, shape, and location of the fluid sign with consensus. The fluid sign was correlated with the cause, age, and severity of the fracture. The diagnosis was confirmed with surgery, follow-up MR imaging, clinical follow-up, or unequivocal imaging findings. Wilcoxon and chi(2) tests were used to assess significance. RESULTS: In fractured vertebral bodies, the fluid sign was adjacent to the fractured end plates and exhibited signal intensity isointense to that of cerebrospinal fluid. The fluid sign was linear (n = 16), triangular (n = 5), or focal (n = 2) and was significantly associated with osteoporotic fractures (21 [40%] of 52; P <.001). The fluid sign occurred in two (6%) of 35 neoplastic compression fractures. Histologic examination demonstrated osteonecrosis, edema, and fibrosis at the site of the fluid sign. There was a tendency toward older fractures exhibiting the fluid sign, but this relationship was not significant (P >.05). In osteoporotic fractures, the fluid sign was significantly associated with fracture severity (P <.05). CONCLUSION: The fluid sign is featured in acute vertebral compression fractures that show bone marrow edema. It can be an additional sign of osteoporosis and rarely occurs in metastatic fractures.

Aged↗
PubMedDate not supplied

Dose reduction in multislice computed tomography.

OBJECTIVE: Evaluation of the attenuation-based on-line modulation of tube current on multislice computed tomography (CT) to explore the potential of this dose-saving technique. METHODS: Fifty-five patients with follow-up CT examinations were scanned without and with a CARE Dose (Siemens Medical Solutions, Erlangen, Germany). The applied dose, image noise, and subjective image quality were evaluated. The reduction in patient exposure was determined by obtaining the effective milliamperes per second for each reconstructed scan and the absolute dosage requirement for the whole scan. RESULTS: The dose reduction achieved by applying the attenuation-based on-line modulation of tube current was 29.4% +/- 3.1% (P=0.002) for all scans, 30.5% +/- 3.2% (P=0.002) for the thorax scans, 29.7% +/- 2.9% (P=0.002) for the abdomen scans, and 28.7% +/- 2.7% (P=0.003) for the thorax and abdomen scans together. No significant restrictions in image quality were observed. CONCLUSIONS: Remarkable dose reduction can be obtained using the attenuation-based on-line modulation of tube current on multislice CT without compromising image quality.

Aged↗