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Biomedical subjects

M Breitenseher

Publications and source records attributed to M Breitenseher.

At least 19 recordsLinked to original sources
PubMed2000

[Diagnostic imaging in femur head necrosis].

Diagnosis of avascular necrosis (AVN) of the hip has been improved by the technical progress of imaging modalities during the last decade. For a long period, only plain radiographs had been available. Scintigraphy and computed tomography contributed to differential diagnosis and early detection of bone necrosis. In the meantime, MR imaging has gained special value in the evaluation of AVN. It is now the method of choice for early detection as well as for assessment in later stage disorders. Using the ARCO system, all imaging modalities and their diagnostic viability are described. Findings regarding the different stages of AVN are correlated to tissue-specific changes.

Diagnostic Imaging↗
PubMed2000

[Pathomorphological aspects and repair mechanisms of femur head necrosis].

The pathomorphologies of non-traumatic femoral head osteonecroses (ON) are usually similar, despite various known pathogenetic factors. The size and position of the subchondral bone and marrow segment, becoming necrotic after the ischemic event(s), and the kind of repair processes determine the time course and thus the fate of this hip joint disease. Four cases of conservatively or core decompression-treated femoral head ON were selected to demonstrate differently effective repair mechanisms which are discussed in respect to existing therapeutic concepts. Diagnostic criteria from magnetic resonance imaging follow-ups were correlated with light microscopy findings on undecalcified ground and microtome sections from femoral heads retrieved at total joint replacement. Initial stage (ARCO 0) and reversible early stage ON (ARCO 1) after incomplete ischemias can apparently show spontaneous sufficient repair. After extensive and complete ischemia, however, ON progresses without detectable changes on plain radiographs into irreversible early stage ON (ARCO stage 2). Only in exceptional cases (with small, medially located necroses), a spontaneous sufficient repair seems possible. Usually, early ARCO stage 2 ON with intact articular surface shows no remodeling of the subchondral necrotic bone and fatty marrow, but only ineffective repair with fibrovascular tissue invasion and bone resorption at the vital bone border. Repeated bone appositions on partly resorbed necrotic trabeculae form the sclerotic rim in this pathognomonic reactive interface. New bone formation can also be increased underneath the necrotic area and reactive interface when surrounded by accompanying bone marrow edema. Core decompression in ARCO stage 2 ON, even if it reaches the necrotic lesion, can at best delay progression of the disease, but never leads to complete reconstruction of the necrotic area. More likely, after both conservative and operative treatment, destructive resorption without effective consecutive bone formation will lead sooner or later to collapse of the articular surface and thus to mechanical instability of transition stage ON (ARCO stage 3). On the other hand, this subchondral fracture can apparently also cause reconstructive repair which, by involving chondral and membranous ossification in this "creeping substitution", can reduce the necrotic area. However, it cannot prevent progression into late stage ON (ARCO stage 4) with secondary joint destructions. Principally, besides the rare sufficient repair in initial and certain early ON, three forms of insufficient repair in the necrotic area can be distinguished: lack of remodeling, destructive remodeling, and reconstructive remodeling. To date, no therapeutical intervention exists which leads to complete healing of irreversible ON stages by reconstructive repair. Improved understanding of pathomorphology and repair mechanisms, however, could be the basis for future therapeutical concepts which should aim at the complete regeneration of the osteonecrotic area.

Adult↗
PubMed2000

["Transient osteoporosis" as a special reversible form of femur head necrosis].

There is still controversy whether transient osteoporosis of the hip joint represents a distinct self-limiting disease, or reflects only an early, reversible subtype of non-traumatic osteonecrosis (ON). Transient osteoporosis has several synonyms: algodystrophy of the hip; transient marrow oedema; or bone marrow oedema syndrome--BMOES. Clinical presentation of BMOES shows mechanical hip joint pain, ON risk factors, and a diffuse bone marrow oedema in MR imaging. Histomorphological changes resemble early ON, but with diffuse sufficient repair in BMOES and focal and insufficient repair only at the border of the necrotic lesion in ON. Therefore the clinical course and outcome are significant different, with restitution occurring in BMOES, while progressive destruction of the joint takes place in ON. So far, the preferred treatment strategies are protected weight bearing for BMOES, but operative treatment for ON. In a prospective study of patients with BMOES, the clinical, radiographic, and MRI course of 43 hip joints after core decompression treatment were investigated. All patients showed immediate relief of pain after surgery and the average duration of symptoms with conservative treatment could be dramatically reduced by core decompression from 6 months down to 2 months. There were no perioperative complications. Based on our experience with over 100 BMOES patients, we are convinced that this syndrome represents not a distinct disease but an early reversible subtype of non-traumatic ON. Due to the excellent clinical results of core decompression, we recommend this operative therapeutical concept in patients with painful BMOES.

Adult↗
PubMed2000

[The value of core decompression in treatment of femur head necrosis].

Core decompression of the necrotic area for treatment of idiopathic osteonecrosis of the femoral head was developed and published by Ficat and Arlet in 1962 within the scope of their "Functional exploration of bone". The mode of action is attributed to a reduction of the intramedullary pressure in the bony compartment of the femoral head. The possibilities of repair and bone regeneration following core decompression are still discussed controversially. Core decompression is a common but not generally accepted procedure in the treatment of idiopathic osteonecrosis of the femoral head. After first publications of positive mid- and long-term effects, some subsequent studies judged it as an ineffective and high-risk method. Analysis of the literature shows that the effectiveness of core decompression depends on the stage of osteonecrosis at the time of surgical intervention. Prognosis is influenced by the extent and location of the necrotic area, the presence and amount of head depression, and continued risk factors--mainly corticoid medication. The best prognosis can be given for patients with a small, medial-centrally located necrosis without head depression. The classification according to Ficat appears to be insufficient, as the extent and localization of the necrotic area are not assessed. Magnetic resonance imaging has become a diagnostic gold standard, as radiographic diagnosis showed poor sensitivity and specificity, especially in the early stages of the disease. As an essential part, MRI was integrated into the new classification of the "Association Internationale de Recherche sur la Circulation Osseuse" (ARCO). On account of the literature and our own experience, treatment by core decompression can be recommended in cases of reversible early stages of osteonecrosis (ARCO 1), as well as in those cases of irreversible early stages (ARCO 2) that show a medial or central location of the necrosis with an extent of less than 30% of the femoral head. Once the disease reaches the irreversible early stage, complete recovery cannot be expected. In these cases only reduction of pain and retardation of the natural course of the osteonecrosis are possible to gain time until total hip replacement is unavoidable.

Decompression, Surgical↗
PubMed1999

[MRI of the ankle joint. Comparison of the 1.0-T and the 0.2-T units].

PURPOSE: Comparison of ankle joint injuries with different MR systems and at different field strengths. METHOD: Ten patients with acute ankle injuries were examined using mid-field (1.0 T) and dedicated low-field (0.2 T) MR units. Findings of ligamentous injury, sinus tarsi involvement, bone injury, and tendon injury were correlated. RESULTS: There was no significant difference between mid- and low-field MR imaging for ligamentous injuries (chi 2 = 0.0395), sinus tarsi changes bone injuries (chi 2 = 0.0507; critical value = 5,991). CONCLUSION: This study showed good agreement in pathological findings in ankle injury on mid-field and low-field MR imaging.

Acute Disease↗
PubMed1999

[MRI arthrography of the ankle joint].

Due to its superior soft tissue contrast conventional MRI is the imaging method of choice in the evaluation of ankle joint disorders. Conventional MR imaging can accurately demonstrate normal or acutely injured ligaments; however, in subacute and chronic injury joint fluid necessary for delineation of injured ligaments is absent and MR arthrography should be performed. MR arthrography uses the intraarticular injection of contrast material to distend the joint, yielding improved discrimination of intraarticular structures. This joint distension with MR arthrography is also helpful in the staging of osteochondritis dissecans, since in cases of unstable lesions tracking of contrast material into the interface can be more easily demonstrated. Finally, high contrast and joint distension by MR arthrography improves the detection of intraarticular loose bodies, which often require surgery. MR arthrography, although invasive, may provide additional information in various ankle joint disorders.

Ankle Injuries↗
PubMed1999

[Filmless magnetic resonance tomography. Advantages and disadvantages in comparison with film reports].

At our hospital, an average MRI examination comprises 170 images. These examinations were evaluated exclusively on digital reporting systems with two high-resolution monitors for a period of 1 year. A retrospective analysis of this reporting method in comparison with films on a conventional viewing wall was performed with subjective and objective data. Radiologists and technicians were requested to evaluate the system on a subjective scale from 1 to 5 for seven topics (image analysis, inspection, time for reporting, handling, comparison with previous reports, quality of PC laser prints, training period). Moreover, personal interviews were conducted and protocols taken. Patient and image frequency, film costs, data transfer time and amount of system failures were evaluated as objective data. The most important results were: Two thirds of the film checking radiologists prefer the conventional viewing walls over the computer monitors. However, 70% of the residents prefer using the computer monitor for reporting. Seventy percent of the interviewed radiologists considered comparison with former examinations on film very difficult. Digitizing of former MRI examinations was not a convincing method; printing on a standard PC laser printer was considered to yield insufficient quality. The different acceptance between radiologists and residents seems to be related to different experiences. The reduction in film costs (48.6%) will improve further with complete PACS installation in the whole hospital. Data transfer rates are still poor; further improvement of network performance is necessary for convenient work. One whole MRI examination and report could be stored on CD-ROM for a cost of less than 2 euros. This could be a future means of cheap archiving and documentation suitable for viewing on any PC with DICOM III viewer. Images and reports could stay with the patients as in the past.

Computer Peripherals↗
PubMed1999

[Staging of musculoskeletal tumors in diagnostic imaging].

The staging of primary malignant bone and soft tissue tumors requires adherence to a unified staging system. The staging system of the American Joint Commission for Cancer, the Enneking system, and the Hajdu system are described in respect of the radiologic staging criteria. Plain film radiography can estimate the biological aggressiveness of a bone tumor and in many cases narrow the differential diagnosis. Computed tomography is most sensitive in depicting cortical erosions and calcified periosteal reactions as well as in screening for distant metastasis. Angiography is mainly employed for vascular tumors and for the monitoring of interventional procedures such as tumor embolization. For both bone and soft tissue tumors, magnetic resonance tomography is the method of choice for the staging of intra- and extramedullary tumor extension, for the differentiation of neighboring compartments, and in the detection of invasion of the regional neurovascular bundle. After administration of contrast agents, the mode of enhancement gives further information on the nature of the tumor. With consistent application of the staging criteria in preoperative imaging, limb-saving therapy can be employed more often and the prognosis of the disease can be improved.

Bone Neoplasms↗
PubMed1999

Discrimination between fluid, synovium, and cartilage in patients with rheumatoid arthritis: contrast enhanced Spin Echo versus non-contrast-enhanced fat-suppressed Gradient Echo MR imaging.

PURPOSE: The aim of this study was to compare fat-suppressed T1-weighted 3D-Gradient Echo (GE)-images and conventional T1-weighted contrast-enhanced SE images in the assessment of patients with rheumatoid arthritis in an attempt to improve discrimination of inflamed synovium, joint fluid, and cartilage. PATIENTS AND METHODS: 28 knee joints in 20 patients with rheumatoid arthritis were examined with a 3 D-GE-T1 weighted sequence with frequency-selective fat suppression (Flash 3D fat sat) and T1-weighted SE-sequences after intravenous gadolinium-containing contrast agent administration using a 1.5T system. Differentiation of cartilage, synovium, and joint effusion was assessed on both sequences qualitatively by two observers and quantitatively by signal intensity measurements. RESULTS: Qualititative analysis revealed higher grading rates for cartilage/fluid differentiation with fat-suppressed T1-weighted GE images than contrast enhanced T1-SE images. Quantitative analysis by measurements of contrast-to-noise ratios revealed significantly higher rates for the Flash 3D fat sat with regard to cartilage/fluid discrimination, significantly higher rates for T1-SE post-contrast for cartilage/synovium discrimination, and significantly higher rates for T1-SE post-contrast for synovium/fluid discrimination. CONCLUSION: 3D-GE-imaging with fat-suppressed T1 weighted sequences allows sufficient differentiation of cartilage and joint fluid in patients with rheumatoid arthritis without application of contrast agents and may assist in monitoring disease progression and response to therapy. The higher contrast to noise ratios of cartilage/synovium and synovium/fluid on T1-SE images following administration of gadolinium-containing contrast agents may improve detection of disease activity.

Adult↗
PubMed1999

MRI visualization of proteoglycan depletion in articular cartilage via intravenous administration of Gd-DTPA.

The effect of intravenous administration of gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) on MR images was studied in vitro, using pathologic osteochondral specimens removed during surgery for total endoprosthesis, and in vivo, on a group of volunteers. In ex vivo specimens, lesions of different shape having lower T1 were detected which corresponded to areas with depleted proteoglycans found histologically. In vivo experiments on young volunteers showed that the time course of cartilage enhancement was different for different anatomies. The time for maximum enhancement ranged from 45 min for the ventral femoral condyle to 270 min for patellar cartilage.

Adult↗
PubMed1999

Magnetic resonance arthrography (MRA) in the postoperative shoulder.

To evaluate changes in capsular mechanisms and the labroligamentous complex with magnetic resonance arthrography (MRA) after shoulder surgery and to establish possible criteria for the expected post-operative appearance of the shoulder. MRA of the shoulder was performed in 16 patients, before and 6 months after undergoing arthroscopic surgery for recurrent unidirectional dislocation. MR studies were performed after application of a constant amount of contrast solution (2 mmol Gd-DTPA). Axial and coronal oblique T1-weighted images were obtained with and without fat suppression techniques. Anterior (a) and posterior (p) capsular distances were measured, and the p/a ratio was established. Capsule thickness, capsular leaking, estimation of the volume of the axillary recess, appearance of the glenohumeral ligaments, and evidence of labral lesions were compared on pre- and postoperative images. Mean anterior capsular distance (a) decreased from 9.73 +/- 1.03 mm preoperatively to 5.27 +/- 2.49 mm postoperatively, whereas dorsal capsular distance (p) increased from 6.13 +/- 2.36 to 8.93 +/- 2.37. The p/a ratio increased from 0.64 +/- 0.25 to 2.36 +/- 2.54 (p = 0.007). Capsular leaking was suspected preoperatively in seven patients, but was not evident postoperatively. Capsular thickness and the estimated volume in the axillary recess did not change significantly. Contrast extension into pre-existent labral tears (nine patients) decreased or were not evident postoperatively. Changes in the appearance of the glenohumeral ligaments were found in six patients. Changes in capsular distances might be indicative of a decreased capsular laxity and could be a valuable criterion in the evaluation of the postoperative shoulder. Postoperative follow-up of labral tears is demonstrated by a decrease in contrast extension into or under a tear. Reactive capsular thickening or scar tissue formation can be reactive or preexistent. Changes in ligaments might be secondary to surgery. MRA may be helpful in the reevaluation of patients with suspected recurrent instability.

Adolescent↗
PubMed1999

[Occult fractures of the wrist joint: high resolution image magnification roentgen versus MRI].

PURPOSE: To compare the diagnostic value of high definition macroradiography and MRI in patients with the suspicion of occult wrist fractures. MATERIALS AND METHODS: In a prospective study, 23 patients with clinically suspected wrist fractures and normal initial plain radiographs underwent high resolution macroradiography and MR imaging shortly after trauma. Macroradiographs were taken with a microfocus tube using an anode of 0.03-0.3 mm providing a 4x magnification of the wrist, which was obtained in 4 projections. MR images were performed on a 1.0 T MR unit in coronal planes using T1 weighted SE, T2.-weighted 3D GE, and Turbo-STIR sequences. Follow-up radiographs after 6 weeks were used to confirm the diagnosis of a primary occult wrist fracture. RESULTS: Macroradiography depicted 5 wrist fractures: 4 fractures of the scaphoid bone and 1 fracture of the capitate bone. MRI demonstrated 11 fractures (one of them false-positive): 9 fractures of the scaphoid bone and two fractures of the capitate bone. Using macroradiography, the sensitivity for the detection of occult fractures of the wrist was 50% with a specificity of 100%, using MRI the sensitivity was 100% with a specificity of 92%. CONCLUSION: MRI seems to be superior to high resolution macroradiography in the detection of occult scaphoid fractures and thus is recommended in the management of patients with clinically suspected scaphoid fractures not evident on initial plain films.

Adolescent↗
PubMed1999

Importance of subchondral bone to articular cartilage in health and disease.

The almost absolute barrier to diffusion of nutrients between articular cartilage and subchondral bone does not exist. These anatomic regions represent a functional unit. Repetitive overloading in degenerative disease leads primarily to lesions in the subchondral region (including vessels), which in turn impede flow of nutrition to articular cartilage. As a result, in degenerative joint disease the subchondral region shows reactive enhanced vascularization and heightened metabolism with insufficient repair. In aging, however, vascularization and metabolism are decreased; no repair takes place. In many cases, MRI allows visualization of these subchondral abnormalities. It also demonstrates the basic similarities of degenerative osteoarthritis, osteochondritis dissecans, and avascular necrosis. These different entities may have the same basic etiology but with different disease severity.

Arthrography↗
PubMed1999

The postoperative shoulder.

Because disability and pain may persist or recur after shoulder surgery, visualization of the postoperative shoulder before further treatment is of great interest. Postoperative status is reevaluated most frequently after rotator cuff repair, capsulorrhaphy in patients with chronic instability, and acromioplasty, where postoperative symptoms are clinically difficult to distinguish from rerupture or inadequate surgical results. Postoperative evaluation or follow-up after surgical treatment of tumors or surgical repair of shoulder injuries are other potential indications. Whereas surgical procedures for osseous components primarily will be evaluated by plain film radiographs, magnetic resonance imaging is a valuable tool for other sites of surgical treatment, such as soft-tissue components, with further potential indication for magnetic resonance arthrography. This article focuses on normal and abnormal postoperative findings in the shoulder, with emphasis of magnetic resonance imaging, and discusses specific findings based on magnetic resonance arthrography.

Acromion↗
PubMed1999

Magnetic resonance imaging of the postoperative knee.

Due to the recent development of arthroscopic techniques in meniscal surgery and anterior cruciate ligament reconstruction, an increasing number of postoperative patients are referred for a magnetic resonance examination of the knee because of recurrent injury. Contrary to the nonoperative patient, T2-weighted sequences and, in unequivocal cases, magnetic resonance arthrography play the most important role in the evaluation of a possible meniscal retear. In patients with anterior cruciate ligament reconstruction, the changes of the magnetic resonance appearance of the anterior cruciate ligament graft during the first year after surgery must be considered in the diagnosis of retears. Recent developments in articular cartilage defect repair and the possible role of magnetic resonance imaging in the follow-up are discussed.

Anterior Cruciate Ligament↗
PubMed1999

The postoperative spine.

During the last decade, magnetic resonance imaging (MRI) mostly has replaced computed tomography for evaluation of spinal surgery patients. The inherent advantages of MRI are obvious for this particularly difficult field of imaging. With MRI, it is possible to demonstrate anatomic as well as pathological and iatrogenic changes in three different imaging planes and countless neighboring planes and to obtain a superior view of the complex postoperative situation regardless of the spinal level imaged. Soft-tissue masses in particular can be identified more readily and located within three-dimensional space. One of the major advantages is that the nature and histology of the mass can be estimated precisely using different MR sequences in combination with intravenous contrast media. The most important benefit may be demonstration of inflammatory and hemorrhagic masses in the early postoperative periods (with special emphasis on alterations visible in the spinal cord itself) as well as repair processes and ongoing degeneration in later stages. This visualization is possible even when their extent is limited. In the postoperative spine, the application of MRI was facilitated with the advent of new materials, such as titanium alloys, used for surgical instrumentation. These new materials limit the amount of artifacts visible on MR images. Earlier implants made of other metallic material prohibit the use of computed tomography in the spine. This article provides a brief overview of the progress in spinal surgery and focuses on the developments in MRI techniques during the last decade. Technical questions about imaging of spinal instrumentation are discussed. "Normal" postoperative findings needed for interpretation of pathologic conditions are also discussed. Finally, the most important frequently asked questions from referring surgeons that radiologists must be able to answer by MRI are presented.

Alloys↗
PubMed1999

Dry versus conventional laser imagers: film properties and image quality.

The authors compared image quality and stability with a dry laser imager versus a conventional wet laser imager. Hard copies of 56 magnetic resonance imaging and computed tomographic studies were analyzed for gray-scale distribution and temperature stability. Results with the dry laser imager did not reach the quality of results with a wet laser imager, but the performance and ecologic criteria were sufficient to make use of this technique advantageous.

Calibration↗