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  • 1
    Electronic Resource
    Electronic Resource
    High Resolution Magnetic Resonance Imaging of the Calcaneus: Age-Related Changes in Trabecular Structure and Comparison with Dual X-Ray Absorptiometry Measurements (1997)
    Springer
    Calcified tissue international 60 (1997), S. 139 -147 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Calcaneus — Trabecular structure — Magnetic resonance imaging — BMD.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 ± 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1–2% and 3–6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r 2= 33.7%, P 〈 0.0037), I.Th (r 2= 26.6%, P 〈 0.0118), I.Sp (r 2= 28.9%, P 〈 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (− 0.52%/year), I.Th (−0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900204
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dedicated extremity MR imaging of the foot and ankle (2000)
    Springer
    European radiology 10 (2000), S. 467-475 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Ankle – MRI – Foot – Extremity MRI – Low-field MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this review is to provide illustrative examples of diseases of the foot and ankle when imaged with a low-field MR imaging system. A retrospective review of 268 foot and ankle examinations, performed in our institution within the past 3 years with a 0.2-T (Artoscan Esaote, Genoa, Italy) dedicated extremity MR system was done. Additionally, illustrative comparison with conventional radiography and high-field MR imaging is presented in patients in whom these examinations were also performed. Although motion artifact limited the value of a few studies, in the majority of examinations low-field MR imaging provided diagnostic image quality for the full spectrum of disorders affecting the foot and ankle and seemed to be a feasible alternative to high-field MR imaging in establishing an accurate diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050078
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Assessing radiographically occult upper extremity fractures with dedicated extremity MRI (2000)
    Springer
    Emergency radiology 7 (2000), S. 339-348 
    Details
    ISSN: 1438-1435
    Keywords: Key words Magnetic resonance imaging, low-field-strength imaging – Extremities, MR – Fractures, MR – Trauma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To examine the utility of low-field, dedicated extremity MRI for assessing acute upper extremity trauma in patients with radiographs that are negative for fracture. Secondly, to determine which sequences are most useful when screening for fractures. Methods: Forty-four of 46 patients with acute upper extremity trauma and initial radiographs negative for fracture were imaged with a 0.2-T MRI system. Findings were verified with follow-up clinical assessment and plain radiography. Results: In 21 patients, dedicated extremity MRI demonstrated 26 ultimately proven occult fractures, none of which were seen on the initial conventional radiographs. True fractures demonstrated marrow edema and a linear fracture line on low-field MRI. One bone contusion showed edema with no fracture line and was misdiagnosed as a fracture. Low-field MRI correctly identified 23 remaining patients with no fracture. Sensitivity and specificity for fracture in the 44 patients successfully imaged were 100 % and 96 %, respectively. Additionally, 21 soft-tissue injuries were found incidentally by MRI. However, these may not merely be incidental findings of an acute nature, but may very well be chronic, and therefore merit no specific treatment. T1-weighted gradient-echo and short-tau inversion recovery sequences demonstrated the fracture line and marrow edema to best advantage, and were thus the most useful sequences to assess fractures on low-field MRI. Conclusion: Extremity MRI is highly sensitive and specific for radiographically occult fractures of the upper extremity and can also identify associated soft-tissue injuries. In our study, the management was altered in 45 % of the patients following MRI. When adequate sequences are used this modality can direct appropriate therapy while obviating the added expense and morbidity of unnecessary immobilization and follow-up imaging of patients without fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00011854
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    Paper (German National Licenses)
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