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  • 1
    ISSN: 1432-0509
    Keywords: Key words: Magnetic resonance imaging—Phased array coil—Anal fistula—Rectal neoplasm—Anal sphincter defect.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: To evaluate the feasibility of a high-resolution magnetic resonance imaging (MRI) technique in detailed imaging of the anal sphincter and lower pelvic region without the use of an endoluminal coil. Methods: MRIs with an external phased array coil (T1- and T2-weighted turbo spin echo) were performed in 22 volunteers and 12 patients with an anal fistula, an anal sphincter defect, or a rectal tumor. The normal scans were evaluated by three independent observers. The scans of the patients were compared with surgical and/or histologic findings. Results: The anal sphincter was visualized with detail. In the anal canal, hemorrhoidal tissue and the submucosae ani muscle could be seen. The MRI technique also allowed detailed imaging of anatomical structures above the pelvic floor. The MR findings in the 12 patients showed exact correlation with surgery and/or histology. Conclusions: High-resolution MRI of the anorectal region without an endoluminal coil is feasible. The MR technique with an external phased array coil allows detailed imaging of the anal sphincter at rest, the rectum, and the surrounding pelvic structures with one single investigation. The results are promising and suggest useful applications in the management of anorectal diseases.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0509
    Keywords: Key words: Rectum—Recurrence—Magnetic resonance imaging—Computed tomography—Neoplasms—Gastrointestinal tract.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: We compared high-resolution magnetic resonance imaging (MRI) with computed tomography (CT) in the assessment of tumor infiltration in surrounding structures for locally advanced primary and recurrent rectal cancer. Methods: Twenty-six patients with operable, locally advanced rectal cancer (15 recurrent and 11 primary) were evaluated with conventional pelvic CT and 1.5-T high-resolution MRI with a quadrature phased-array coil. The images were scored for invasion of nine neighboring pelvic structures, and the results were compared with surgical and histologic findings. Results: A total of 234 structures in 26 patients was evaluated for tumor invasion. For MRI the, sensitivity was 97% and the specificity 98%; for CT, the sensitivity was 70% and the specificity was 85%. The difference in performance was statistically significant (p 〈 0.001). The failure most frequently made on CT was the false-positive prediction of pelvic floor and piriform muscle invasion (14), whereas MRI showed only four false-positive predictions. MRI correctly predicted all four cases of sacral bone invasion, three of which were missed by CT. MRI was accurate in 20 patients (80%) and CT in only five patients (19%). Conclusion: High-resolution MRI using a quadrature phased-array coil is highly accurate and superior to CT in predicting tumor infiltration in surrounding structures for locally advanced primary or recurrent rectal cancer and is recommended in the preoperative work-up of these tumors.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 9 (1999), S. 1285-1289 
    ISSN: 1432-1084
    Keywords: Key words: Peripheral contrast ; Enhanced MR angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Magnetic resonance angiography has taken a huge step forward since the introduction of contrast-enhanced MR angiography using gadolinium chelates. The more conventional MR angiographic techniques, such as time-of-flight and phase-contrast MR angiography, have been ousted by contrast-enhanced MR angiography in most vascular areas. However, in imaging the lower extremities, the major obstacle is the length of the vascular tree. In order to cover the entire peripheral vasculature, at least two to three fields of view are required. Using contrast-enhanced MR angiography, the best results are obtained if the vessels of interest are imaged during passage of a bolus of contrast material. Vessel-to-background contrast in subsequent acquisitions using subsequent injections of contrast material is hampered by recirculation and leakage of previously injected gadolinium, enhancing both the venous system and surrounding tissue. To overcome this problem several research groups have come up with various solutions. The three main strategies employed can be classified as either bolus catch, bolus chase, or bolus track techniques. The purpose of this article is to explain working mechanisms of the three bolus imaging strategies for imaging both inflow and outflow vessels of the lower extremities, to show their advantages and disadvantages, and to review results described in the literature in imaging patients using these techniques.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 9 (1999), S. 1765-1774 
    ISSN: 1432-1084
    Keywords: Key words: Peripheral occlusive vascular disease ; Peripheral MR angiography ; Time-of-flight MRA ; Contrast-enhanced MRA ; Gadolinium chelates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Atherosclerotic disease of the lower extremities is a common disorder in western society. Its debilitating nature calls for accurate diagnosis and treatment. The gold standard for diagnosing this disease by depiction of vessel morphology is X-ray angiography (either conventional or digital subtraction angiography). However, the invasive nature of this technique and the possible harmful effects of iodinated contrast agents have led to the idea that non-invasive MR angiography might be a good alternative for acquiring information about vessel morphology. Most extensively studied was time-of-flight MR angiography. Although first results with this technique were encouraging, it is now apparent that time-of-flight MR angiography is hampered by the virtue of which it exists, since blood flow not only generates vessel-to-background contrast, but is also the cause of disturbing artifacts. However, with the introduction of minimally invasive contrast-enhanced MR angiography, using gadolinium chelates to reduce the T1 of blood, image quality has improved dramatically. Moreover, using contrast-enhanced MR angiography, high-resolution three-dimensional data about the entire peripheral vascular tree can be obtained within several minutes, which might make MR angiography a true competitor of X-ray angiography as a diagnostic tool in the clinical work-up of a patient with complaints of peripheral atherosclerosis. The purpose of this article is to explain working mechanisms and usefulness of both time-of-flight and contrast-enhanced MR angiography.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1084
    Keywords: Key words: Renal arteries – MR imaging – Flow dynamics – Phase imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to evaluate the validity and reproducibility of breath-hold and respiratory triggered phase-contrast (PC) MR imaging techniques in the measurement of renal artery blood flow. In 12 healthy subjects cardiac-gated PC flow measurements were obtained in the renal arteries using a breath-hold and a respiratory-triggered technique. The flow measurements were repeated in each renal artery separately. Comparison between the sum of flow measurements in the renal arteries and the difference in aortic flow measurements above and below the renal arteries served as an internal control. The flow measurements showed a good reproducibility both with the breath-hold (r = 0.92, p 〈 0.0001) and with the respiratory-triggered (r = 0.91, p 〈 0.0001) technique. The validity of both methods was good and there was no statistically significant difference. Reproducible quantitative measurements of renal artery blood flow are possible with respiratory controlled, cardiac-gated, PC MR imaging.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to investigate the diagnostic value of ultrasound in children with recurrent abdominal pain and to estimate the clinical relevance of rare organic causes of abdominal pain in these patients, we prospectively examined 93 children aged between, 5.5 and 12 years by means of abdominal ultrasound. In 3 patients (3.2%) an anatomic abnormality was detected, which could not account for the abdominal pain. We conclude that many organic abnormalities, that could be diagnosed by ultrasound, are clinically irrelevant as a cause of recurrent abdominal pain in children and therefore ultrasound does not significantly contribute to the diagnosis. However, ultrasound can still play a role in the work-up of children with recurrent abdominal pain in avoiding unnecessary radiologic X-ray procedures.
    Type of Medium: Electronic Resource
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