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A Stäbler

Publications and source records attributed to A Stäbler.

At least 19 recordsLinked to original sources
PubMed2006

Should 3K zoom function be used for detection of pneumothorax in cesium iodide/amorphous silicon flat-panel detector radiographs presented on 1K-matrix soft copies?

The purpose of the study was to evaluate observer performance in the detection of pneumothorax with cesium iodide and amorphous silicon flat-panel detector radiography (CsI/a-Si FDR) presented as 1K and 3K soft-copy images. Forty patients with and 40 patients without pneumothorax diagnosed on previous and subsequent digital storage phosphor radiography (SPR, gold standard) had follow-up chest radiographs with CsI/a-Si FDR. Four observers confirmed or excluded the diagnosis of pneumothorax according to a five-point scale first on the 1K soft-copy image and then with help of 3K zoom function (1K monitor). Receiver operating characteristic (ROC) analysis was performed for each modality (1K and 3K). The area under the curve (AUC) values for each observer were 0.7815, 0.7779, 0.7946 and 0.7066 with 1K-matrix soft copies and 0.8123, 0.7997, 0.8078 and 0.7522 with 3K zoom. Overall detection of pneumothorax was better with 3K zoom. Differences between the two display methods were not statistically significant in 3 of 4 observers (p-values between 0.13 and 0.44; observer 4: p = 0.02). The detection of pneumothorax with 3K zoom is better than with 1K soft copy but not at a statistically significant level. Differences between both display methods may be subtle. Still, our results indicate that 3K zoom should be employed in clinical practice.

Adult↗
PubMed2005

[Hereditary motor and sensory neuropathy (HMSN) with hypertrophy of the cauda equina and concomitant demyelinating white matter lesions].

Hereditary motor and sensory neuropathy (HMSN) is thought to almost exclusively affect the peripheral nervous system. We report the case of a 48-year-old patient with a longstanding history of HMSN type I who developed signs and symptoms of a cauda equina compression and of a central nervous system relapsing-remitting demyelinating white matter disease. Gross enlargement of the cauda equina fibers was detected by MR imaging of the lumbar spine. Cranial MR imaging revealed demyelinating white matter lesions. This case suggests that peripheral neuropathic mechanisms may also affect the central myelin in HMSN type I.

Charcot-Marie-Tooth Disease↗
PubMed2005

[Estimation of diffuse bone marrow infiltration of the spine in multiple myeloma: correlation of MRT with histological results].

PURPOSE: To determine the detection of diffuse bone marrow infiltration with MRI in comparison with histopathological findings. MATERIALS AND METHODS: MRI was performed on 45 patients with histologically proven multiple myeloma and on 30 healthy individuals. Three experienced radiologists read separately Tl-weighted SE sequences, STIR sequences and the combination of Tl-weighted SE and STIR sequences of the spine. Additionally, Tl-weighted SE sequences were obtained after gadolinium administration and the percentage increase in signal intensity was calculated. Bone marrow histology was used as gold standard for assessing the grade of infiltration. A dichotomous decision (infiltration yes/no) was made when assessing the MRI examinations. RESULTS: For the visual detection of diffuse infiltration, the best sensitivity was found with Tl-weighted SE sequences, achieving 71 % on average. The specificity was 89 %. The STIR sequences showed a sensitivity of 61 % and a specificity of 98 %, and the combination of Tl-weighted/STIR-sequences achieved a sensitivity of 65 % and a specificity of 94 %. In comparison with the histological findings, the sensitivity of the Tl-weighted sequences was 35 % for low-grade, 89 % for moderate and 100 % for high-grade infiltration. The application of contrast material with calculation of the percentage signal increase improved the detection by 7 %. CONCLUSION: The sensitivity of the visual detection of diffuse multiple myeloma with unenhanced MRI is limited for low-grade or moderate infiltration, whereas the sensitivity for high grade infiltration is reliable. The specificity is high and the diagnostic confidence improves after application of contrast material with calculation of the percentage increase in signal intensity.

Adult↗
PubMed2003

[The roentgenmorphologic aspects of symptomatic calcifications in patients with calcifying tendinitis of the shoulder: determination of intra- and interobserver variabilities of Gärtner's classification].

AIM OF THE STUDY: The roentgenologic morphology of symptomatic calcified deposits of the rotator cuff can be classified according Gärtner. This classification influences therapeutic procedures and prognosis of clinical outcome in these patients. In the present study intraoberserver-reproducibility and interobserver-reliability of Gärtner's classification were tested. METHODS: Plane radiographs of 100 patients with calcifications of the supraspinatus tendon were classified according the criteria of Gärtner by 6 independent observers twice within 4 months. Intraoberserver-reproducibility and interobserver-reliability were calculated by means of Cohen's kappa-index. RESULTS: kappa-values of intraoberserver-reproducibility had a mean of 0.4208 (SD 0.1299), kappa-values of interobserver-reliability were 0.490 for the first and 0.474 for the second classification. CONCLUSIONS: Determination of intraoberserver-reproducibility gave insufficient to satisfactory results, interobserver-reliability was sufficient. The clinical use of Gärtner's classification to plan therapeutic procedures or to determine clinical prognosis in patients with calcifying tendinitis can be recommended only with limitations.

Adult↗
PubMed2002

[Differentiation of benign osteoporotic and neoplastic vertebral compression fractures with a diffusion-weighted, steady-state free precession sequence].

PURPOSE: To evaluate the diagnostic accuracy of a diffusion-weighted, steady-state free precession (SSFP) sequence for the differentiation of acute benign osteoporotic and neoplastic vertebral compression fractures. METHODS: 85 patients with 102 vertebral compression fractures were examined with MR imaging using a spine array surface coil (Siemens, Vision, 1.5 Tesla). The following sequences were performed in sagittal orientation: T1-weighted spin echo (SE), short-tau inversion recovery (STIR) and a diffusion-weighted SSFP sequence (TR = 25 msec, diffusion pulse length delta = 3 msec). The SSFP images were evaluated qualitatively on a 5-grade scale from strongly hypointense to strongly hyperintense. Quantitative analysis was performed with region of interest measurements (ROI) and calculation of a bone marrow ratio. RESULTS: 60 fractures were due to osteoporosis and 42 fractures were caused by malignancy. "Hyperintensity" in a vertebral fracture on a SSFP sequence provided a sensitivity of 100 % and a specificity of 93 %. The positive predictive value was 91 %, the negative predictive value was 100 %. Quantitative analysis of the bone marrow ratio showed a statistically significant difference between the osteoporosis and the tumor group (p < 0.001). The mean value for the osteoporotic fractures was - 0.32 (SD 0.33) and + 2.07 (SD 1.37) for the tumor group. CONCLUSION: The SSFP sequence provides a high accuracy in the differentiation of benign osteoporotic and neoplastic vertebral compression fractures.

Adult↗
PubMed2002

Influence of extracorporeal shock-wave application on normal bone in an animal model in vivo. Scintigraphy, MRI and histopathology.

There is little information about the effects of extracorporeal shock-wave application (ESWA) on normal bone physiology. We have therefore investigated the effects of ESWA on intact distal rabbit femora in vivo. The animals received 1500 shock-wave pulses each of different energy flux densities (EFD) on either the left or right femur or remained untreated. The effects were studied by bone scintigraphy, MRI and histopathological examination. Ten days after ESWA (0.5 mJ/mm2 and 0.9 mJ/mm2 EFD), local blood flow and bone metabolism were decreased, but were increased 28 days after ESWA (0.9 mJ/mm2). One day after ESWA with 0.9 mJ/mm2 EFD but not with 0.5 mJ/mm2, there were signs of soft-tissue oedema, epiperiosteal fluid and bone-marrow oedema on MRI. In addition, deposits of haemosiderin were found epiperiosteally and within the marrow cavity ten days after ESWA. We conclude that ESWA with both 0.5 mJ/mm2 and 0.9 mJ/mm2 EFD affected the normal bone physiology in the distal rabbit femur. Considerable damaging side-effects were observed with 0.9 mJ/mm2 EFD on periosteal soft tissue and tissue within the bone-marrow cavity.

Animals↗
PubMed2001

Chest imaging with flat-panel detector at low and standard doses: comparison with storage phosphor technology in normal patients.

The purpose of this study was to evaluate the performance of standard-dose and low-dose cesium iodide (CsI)-doted amorphous silicon (a-Si) flat-panel detector technology (FDT) as compared with storage-phosphor technology (SPT) in the depiction of relevant anatomical structures in chest radiography. In 75 patients referred for thoracic CT, digital chest radiographs were randomly obtained with either SPT at a standard dose (speed class S400, n=25), standard-dose FDT (S400, n=25) or FDT at a low dose (S800, n=25). Five radiologists evaluated the visibility of eight pulmonary and mediastinal anatomical structures using a five-point rating scale. To determine statistically significant differences between the three groups, the Mann-Whitney U-test was employed. No statistically significant differences were found in the depiction of eight criteria between SPT and standard-dose or low-dose FDT chest radiographs. The performance of FDT S400 was equal to SPT for most criteria and better for retrocardiac structures and soft tissue. FDT S800 was inferior to both SPT and FDT S400. Standard-dose FDT is equivalent to SPT in the depiction of relevant anatomical structures of the chest. Our results also indicate that a dose reduction of 50% with FDT may result in small but not significant decrease of image quality.

Cesium↗
PubMed2001

Case-oriented computer-based-training in radiology: concept, implementation and evaluation.

BACKGROUND: Providing high-quality clinical cases is important for teaching radiology. We developed, implemented and evaluated a program for a university hospital to support this task. METHODS: The system was built with Intranet technology and connected to the Picture Archiving and Communications System (PACS). It contains cases for every user group from students to attendants and is structured according to the ACR-code (American College of Radiology) 2. Each department member was given an individual account, could gather his teaching cases and put the completed cases into the common database. RESULTS: During 18 months 583 cases containing 4136 images involving all radiological techniques were compiled and 350 cases put into the common case repository. Workflow integration as well as individual interest influenced the personal efforts to participate but an increasing number of cases and minor modifications of the program improved user acceptance continuously. 101 students went through an evaluation which showed a high level of acceptance and a special interest in elaborate documentation. CONCLUSION: Electronic access to reference cases for all department members anytime anywhere is feasible. Critical success factors are workflow integration, reliability, efficient retrieval strategies and incentives for case authoring.

Computer Communication Networks↗
PubMed2001

[Radiofrequency ablation of liver metastases. Technique and initial results].

Primary and secondary malignant hepatic tumors are the most common tumors with a much more higher incidence of hepatic metastases. Chemotherapy and radiation therapy are in general ineffective. Therefore, surgical resection is considered the method of choice in the treatment of malignant hepatic lesions. Due to systemic disease, general medical or procedure-related reasons hindering surgery, only 25 to 45% of the patients with metastatic disease of the liver are suitable for a curative surgical therapy. In resectable lesions thermoablative methods can offer an alternative to the surgical therapy. The most experience exists in radiofrequency ablation techniques. Technique, indications, contraindications, and limitations of the radiofrequency ablation will be discussed together with a presentation of own cases and a review of the literature. In 37 patients the primary technical success rate of the ablation was 97.3% (72 of 74 lesions). In 4 cases a hematoma of the liver capsule occurred. One of these had to be treated interventionally. During the limited follow-up period of 9 months no local recurrency was seen, however 4 patients developed new hepatic metastases. Beside differences in practicability it is not yet clarified if there are differences in the therapeutic efficacy of the different thermoablation methods. Nevertheless, the results of the ablation therapy may parallel the results of the surgical resection. Interstitial thermotherapy can provide a valuable contribution to local tumor control. However, the final significance of the thermoablation techniques within oncological therapy regimens has to be evaluated in further multidisciplinary studies.

Adult↗
PubMed2001

[Benign bone-forming tumors].

Benign bone-forming tumors include osteomas, enostomas, osteoid osteomas, and osteoblastomas. These lesions are often characterized by typical imaging findings on radiographs, CT and MR imaging studies. Radiologic findings and additional clinical information allow for a specific diagnosis in most cases. This review article emphasizes the radiological patterns of benign bone-forming tumors as well as their epidemiological, clinical, and pathological characteristics. In addition, minimally invasive interventional procedures for the therapy of osteoid osteoma are reviewed.

Bone Neoplasms↗
PubMed2001

On the impact of calcified deposits within the rotator cuff tendons in shoulders of patients with shoulder pain and dysfunction.

We wanted to prove the hypothesis that calcified deposits within the rotator cuff tendons are merely an epiphenomenon of complex morphological alterations in the shoulders of patients with shoulder pain and dysfunction. The shoulders of 92 patients with calcified deposits within the rotator cuff tendons as noted on plain radiographs were investigated by means of magnetic resonance imaging (MRI; mean age of patient 51.1 years), as well as the shoulders of 28 age- and sex-matched patients with similar clinical symptoms but without any signs of such calcified deposits on plain radiographs. The MRI protocol comprised a coronal, oblique, T1-weighted, spin-echo sequence, a T2-weighted, turbo spin-echo sequence, a sagittal, oblique, T2-weighted, turbo spin-echo sequence, and an axial, T1-weighted, spin-echo sequence. Furthermore, a coronal, oblique, short tau-inversion recovery sequence and a gradient echo sequence were used. The results were compared with data from healthy, asymptomatic volunteers as reported in the literature. The MRI investigations showed no substantial differences between patients with or without calcified deposits within the rotator cuff tendons, but distinct differences between such patients and healthy, asymptomatic volunteers. For patients with shoulder pain, shoulder dysfunction, and calcified deposits within the rotator cuff tendons, these calcified deposits are most probably not the main cause of the clinical symptoms. Rather, it seems to be useful to consider the results of MRI investigations whenever planning therapeutic procedures for patients with shoulder pain and dysfunction, irrespective of whether or not there are signs of calcified deposits within the rotator cuff tendons on plain radiographs.

Adult↗
PubMed2001

Extracorporeal shock-wave therapy for chronic lateral tennis elbow--prediction of outcome by imaging.

Today the clinical use of extracorporeal shockwave application (ESWA) for the treatment of lateral tennis elbow is hampered by the lack of results from randomized controlled trials and of predictive parameters of clinical outcome. The present prospective study aimed to provide the latter by means of magnetic resonance imaging (MRI). Twenty-three female and 19 male patients with unilateral chronic tennis elbow of the dominant site were clinically examined before and after repetitive low-energy ESWA. MRI was performed before ESWA to evaluate signal intensity changes or contrast enhancement of the common extensor tendon and the lateral epicondyle. After ESWA (mean follow-up period 18.6 months for all patients), clinical evaluation showed a significantly better mean clinical performance after ESWA than before treatment. Interestingly, male patients showed a significantly better mean clinical performance after ESWA than female patients, and male and female patients differed significantly in the signal intensity of the common extension tendon cross-section and tendon thickening on MRI. For female patients, MRI scans could be applied for predicting a positive clinical outcome of ESWA. This study reports the first indication of predictability of positive clinical outcome of the treatment of chronic lateral tennis elbow by ESWA using imaging prior to treatment. This may serve as an important step towards overcoming the therapeutic nihilism with respect to the non-operative management of this condition recently in the literature.

Adult↗
PubMed2001

Imaging of spinal infection.

MR imaging is the modality of choice for the detection, staging, and differential diagnosis of inflammatory disorders of the spine. Infectious spondylitis is characterized by the involvement of two adjacent vertebrae and the intervening disk with severe BME and early destruction of the end plates. The disk space is narrowed and typically exhibits water-equivalent signal intensity on T2-weighted or STIR images. Prevertebral and epidural extensions, abscess formation, enhancement of the BME, the disk space, and the surrounding granulation tissue are well demonstrated by gadolinium-enhanced images. Cervical spondylitis frequently involves more than one level. Bone marrow abnormalities may be subtle at this level and increased signal intensity of the disk space on T2-weighted or STIR images is an important finding. The risk for neurologic complications is increased. Granulomatous infections caused by tuberculosis, brucellosis, fungi, and parasites, including hydatid disease (Echinococcus), are frequently associated with imaging findings different from those seen with nonspecific bacterial infection. In patients with chronic infectious spondylitis, diffuse reactive bone marrow changes with decreased signal intensity on T1-weighted images, increased signal intensity on T2-weighted and STIR images, and increased uptake after gadolinium administration may occur. This phenomenon is probably caused by reactive bone marrow stimulation, simulating diffuse hematologic neoplastic disease. Erosive intervertebral osteochondrosis with bandlike disk gadolinium enhancement and BME, which is commonly associated with local pain, is the most important differential diagnosis of bacterial spondylitis.

Adolescent↗
PubMed2001

[Evaluation of an electromagnetic virtual target system (CT-guide) for CT-guided interventions].

PURPOSE: Evaluation of the accuracy of a new electromagnetic target system for interventional CT-guided procedures with virtual navigation in a previously acquired helical CT. MATERIAL AND METHODS: The new target system CT-Guide 1010 (Ultraguide, Tirat Hacarmel, Israel) for CT-guided interventions was adapted to the video signal of the Somatom Plus 4 and Volume Zoom (Siemens, Erlangen, Germany). A helical CT-dataset including skin-based sensor cubes was transferred to the integrated navigation system inside the scanner room. 50 image-guided interventions and biopsies were performed outside the gantry using virtual navigation to reach the lesion. The accuracy of the procedures was evaluated using documentation of the needle tip with CT-fluoroscopy, results of histology, and follow-up. RESULTS: The deviation between planned and documented needle tip was 2.2 +/- 2.1 mm in 50 procedures. Time between the end of planning-CT and needle positioning using the system was 13 minutes. There were no complications due to the use of the system. CONCLUSION: The CT-Guide allows for virtual real-time navigation with high accuracy. Advantages are the free needle angulation without gantry tilt, use of optimal CT perfusion phase for virtual navigation, and reduction of radiation exposure to the patient and interventionalist.

Adult↗
PubMed2001

Assessment of the position of the distal portion of the ulna in lateral projection radiographs of the wrist: analysis of the influence of pronation-supination and flexion-extension on the pisoscaphoid and the ulnotriquetral distances: a cadaver study.

RATIONALE AND OBJECTIVES: Accurate assessment of the distal radioulnar joint is of paramount importance for the detection of possible dislocation or subluxation. Using a cadaveric model, the authors attempted to establish a quantitative method that would allow identification of normal and abnormal distal radioulnar joint anatomy on well-positioned and rotated conventional radiographs. METHODS: Four cadaveric wrists, in which subsequent sectioning confirmed the absence of disease, and one cadaveric wrist with a circumscribed lesion of the triangular fibrocartilaginous complex were studied. Defined movements in flexion and extension (+/- 10 degrees, 20 degrees, 30 degrees ) and in pronation and supination (+/- 10 degrees, 20 degrees, 30 degrees ) as well as combined flexion/extension and pronation/supination were performed. The ulnotriquetral and the pisoscaphoid distances were assessed in each position. Correlation with cryosections was achieved. RESULTS: A strong linear correlation between the degree of pronation or supination and the pisoscaphoid and ulnotriquetral distances was noted. Flexion and extension produced no significant effect on the pisoscaphoid distance, but a defined shift of the ulnotriquetral distance occurred with increasing flexion and extension. CONCLUSIONS: If all parameters are taken into account, this correlation aids in estimating the degree of possible malpositioning of the wrist during radiography and the degree of subluxation of the distal radioulnar joint. Tabular data with parameters to correct for instances of malrotated images and to estimate the extent of dislocation or malrotation of the distal radioulnar joint are provided.

Cadaver↗
PubMed2001

Cervical spine: postmortem assessment of accident injuries--comparison of radiographic, MR imaging, anatomic, and pathologic findings.

PURPOSE: To assess the ability of postmortem radiography and magnetic resonance (MR) imaging to depict occult cervical spine injuries as compared with anatomic and pathologic findings. MATERIALS AND METHODS: The cervical spines of 10 adult accident victims underwent radiography and MR imaging, with T1-weighted, fast spin-echo T2-weighted, and four gradient-echo pulse sequences. The frozen specimens were cut into 3-mm-thick slices (sagittal plane) and photographed, and microfocus radiographs were obtained. Imaging findings were compared with the anatomic and pathologic findings. RESULTS: Eight of the 10 specimens had 28 posttraumatic lesions: three fractures (two missed at the initial MR imaging reading), 10 facet joint capsule lesions with bleeding, five soft-tissue and ligament lesions, eight disk lesions, and two spinal cord lesions. Radiography depicted one lesion (4%). Two partial ruptures of the anterior annulus fibrosus were depicted at only MR imaging. Initially, 11 of 28 lesions were detected on MR images; retrospectively, 17 of 28 lesions were correlated with anatomic findings. CONCLUSION: Soft-tissue and intervertebral disk and ligament injuries account for 89% (25 of 28) of posttraumatic cervical spine lesions detected on postmortem images. Occult lesions, including apophyseal joint injuries, were found in clinically noninjured cervical spines. MR imaging was limited in the depiction of discrete lesions when T1-weighted non-fat-saturated, fast spin-echo T2-weighted, and gradient-echo pulse sequences were used.

Adult↗
PubMed2001

[Time needs in evaluating digital thoracic images on the monitor in comparison with alternator].

PURPOSE: Evaluation of time efficiency in softcopy reading versus hardcopy reading of digital chest x-rays. MATERIAL AND METHODS: 130 normal and pathologic chest x-rays in two plains were analyzed by 4 experienced radiologist at both a digital workstation and the light box. Reading time and switch time between two patient folders were measured as well as the frequency of post-processing at the monitor. RESULTS: Reading time at the workstation slightly exceeded reading time at the light box; differences were not statistically significant. Post-processing (frequency between 2% and 83%) did not significantly prolong reading time. Mean switch time between two patient folders was 4.3 sec at the workstation and 13.7 sec at the light box. CONCLUSION: As compared to hardcopy reading, softcopy reading of digital chest x-rays does not significantly increase reading time. Switch time between patient folders can be reduced at the workstation by a factor of two to four.

Efficiency↗