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  • 1
    Electronic Resource
    Electronic Resource
    Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions (1996)
    Springer
    Abdominal imaging 21 (1996), S. 427-432 
    Details
    ISSN: 1432-0509
    Keywords: Key words: MRI—Hepatic imaging—RARE—Detection—Characterization.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. Methods: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor–liver signal intensity (T/L) ratios. Results: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion–liver C/N (CSE TE, 90 ms: 18.6 ± 14.0; TSE TE, 90 ms: 16.5 ± 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. Conclusions: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002619900097
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  • 2
    Electronic Resource
    Electronic Resource
    Hydro-MRI for the visualization of gastric wall motility using RARE magnetic resonance imaging sequences (2000)
    Springer
    Abdominal imaging 25 (2000), S. 30-34 
    Details
    ISSN: 1432-0509
    Keywords: Key words: Magnetic resonance imaging—Gastric motility—Contrast agent—Gadolinium.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Although different imaging techniques such as conventional X-ray, ultrasonography, and hydro-computed tomography are available for the imaging of the stomach, none can depict this organ in full size without radiation. Therefore, the study of the entire gastric wall motility of the stomach is difficult and in principle only performable with rapid magnetic resonance imaging (MRI) techniques. T1-weighted imaging sequences have been used for the dynamic study of gastric wall motility. This technique was combined with the oral intake of para- or superparamagnetic contrast agents to achieve sufficient intraluminal contrast. The technique described in the present study is based on a different contrast mechanism. Methods: The stomach was filled with 500 mL of 10% of aqueous dextrose solution, and a strongly T2-weighted fast rapid acquisition with relaxation enhancement (RARE) type imaging sequence was used for data acquisition. No other contrast agents were applied. An ultrafast RARE imaging sequence with an asymmetric phase-encoding scheme was developed to achieve a high temporal and spatial resolution. The scanning time per image was approximately 1 s. Results: The stomach was imaged in full size. The concentric constrictor rings moved from the proximal part of the body toward the antrum. The mean duration for one contraction cycle was approximately 17.9 ± 2.5 s, the mean contractile frequency was 3.4 ± 0.5 s, and the mean spreading velocity was 65.5 ± 3.6 cm/min. Conclusions: The purpose of this study was to demonstrate a new technical approach for a noninvasive dynamic study of gastric motor function with hydro-MRI. This robust method may have clinical application, e.g., in the diagnosis of gastroparesis, and may be extended to the rest of the gastrointestinal tract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/s002619910005
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  • 3
    Electronic Resource
    Electronic Resource
    Pulmonary circulation (1998)
    Springer
    European radiology 8 (1998), S. 698-706 
    Details
    ISSN: 1432-1084
    Keywords: Key words: CT pulmonary arteries ; MRI pulmonary arteries ; MRA ; CTA ; Pulmonary thromboembolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Evaluation of the pulmonary vasculature is mainly indicated in patients with suspected pulmonary thromboembolism. The routine procedure so far is ventilation-perfusion scintigraphy alone or in combination with diagnostic assessment of the legs to rule out deep venous thrombosis. The results are still not reliable for the majority of patients. In the case of equivocal diagnosis, invasive conventional angiography is considered the gold standard. With steady improvements in tomographic imaging techniques, such as computed tomography (CT) or magnetic resonance imaging (MRI), non-invasive alternatives to the routine diagnostic work-up are given. Helical CT and CTA techniques are already in clinical use and estimated to sufficiently serve the demands for detection/exclusion of pulmonary thromboembolism. The disadvantages mainly concern peripheral disease and reconstruction artifacts. MRI and MR angiography have been implemented in the diagnosis of pulmonary vascular disease since the introduction of contrast-enhanced MRA. In breath-hold techniques, the entire lung vascularization can be delineated and thromboemboli can be detected. The clinical experience in this field is limited, but MRI has the potential to demonstrate its superiority over CT due to its improved delineation of the vascular periphery and the more comprehensive three-dimensional reconstruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050462
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  • 4
    Electronic Resource
    Electronic Resource
    Detection of pulmonary nodules with overlapping vs non-overlapping image reconstruction at spiral CT (1999)
    Springer
    European radiology 9 (1999), S. 281-286 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Lung ; Nodule ; Helical CT ; Image processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to analyze whether overlapping image reconstruction increases numbers of pulmonary nodules detected at helical CT. Forty-eight helical CT scans (21with a slice thickness of 10 mm; 27 with a slice thickness of 5 mm) of patients with known pulmonary nodules were reconstructed both with overlapping and non-overlapping image reconstruction. Two readers recorded number and size of pulmonary nodules as well as diagnostic confidence. With overlapping image reconstruction each reader diagnosed more pulmonary nodules (slice thickness 10 mm: +24.0 and +26.7 %, both p 〈 0.01; slice thickness 5 mm: +9.5 and +11.9 %, both not significant) and more “definite” nodules (slice thickness 10 mm: +20.3 %, p 〈 0.05, and +30.8 %, p 〈 0.005; slice thickness 5 mm: +18.0 and +17.0 %, both p 〈 0.05). Nodules diagnosed with overlapping image reconstruction only were almost exclusively smaller than the slice thickness. The increase in number of nodules detected was not associated with a decrease in diagnostic confidence. Overlapping image reconstruction improves detection of pulmonary nodules smaller than the slice thickness at spiral CT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050668
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  • 5
    Electronic Resource
    Electronic Resource
    CT-guided intratumoral gene therapy in non-small-cell lung cancer (1999)
    Springer
    European radiology 9 (1999), S. 292-296 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Computed tomography ; Therapeutic radiology ; Gene therapy ; p53
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The objective of this study was to prove the principle of CT-guided gene therapy by intratumoral injection of a tumor suppressor gene as an alternative treatment approach of incurable non-small-cell lung cancer. In a prospective clinical phase I trial six patients with non-small-cell lung cancer and a mutation of the tumor suppressor gene p53 were treated by CT-guided intratumoral gene therapy. Ten milliliters of a vector solution (replication-defective adenovirus with complete wild-type p53 cDNA) were injected under CT guidance. In four cases the vector solution was completely applied to the tumor center, whereas in two cases 2 ml aliquots were injected into different tumor areas. For the procedure the scan room had been approved as a biosafety cabinet. Gene transfer was assessed by reverse transcription and polymerase chain reaction in biopsy specimens obtained under CT guidance 24–48 h after therapy. Potential therapeutic efficacy was evaluated on day 28 after treatment using spiral CT. The CT-guided gene therapy was easily performed in all six patients without intervention-related complications. Besides flu-like symptoms, no significant adverse effects of gene therapy were noted. Three of the four patients with central injection exhibited gene transfer in the posttreatment biopsy. Gene transfer could not be proven in the two patients with multiple 2 ml injections. After 28 days, four of the six patients showed stable disease at the treated tumor site, whereas other tumor manifestations progressed. Computed tomography-guided injections are an adequate and easy-to-perform procedure for intratumoral gene therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050670
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  • 6
    Electronic Resource
    Electronic Resource
    Noninvasive stress testing of myocardial ischemia: comparison of GRE-MRI perfusion and wall motion analysis to 99 mTc-MIBI-SPECT, relation to coronary angiography (1997)
    Springer
    European radiology 7 (1997), S. 990-995 
    Details
    ISSN: 1432-1084
    Keywords: Key words: MR imaging ; Perfusion ; Wall motion ; Ischemia ; Coronary artery disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. In the evaluation of ischemic heart disease only MR imaging seems to have the potential to assess myocardial perfusion, function, and coronary morphology on a single instrument. The aim of this study was to assess the feasibility of a stress test with dipyridamole (0.56 mg/kg) to analyze myocardial perfusion by Gd first-pass enhancement in ultrafast gradient-recalled-echo MRI (perf-MRI), and wall motion by cine gradient-recalled-echo MRI (Cine-MRI) in one imaging session. Twelve patients underwent complete rest and stress studies; satisfactory MR images were acquired in 10 patients. By 99 mTc-MIBI-SPECT sensitivities to detect ischemic segments were 66.7 % with Perf-MRI, 80.0 % with WM-MRI and 86.7 % for Perf-WM-MRI (Perf-MRI vs Perf-WM-MRI; p = 0.03). Scar was equally detected with a sensitivity of 91.6 % with either MRI technique. Thus, Perf-Cine-MRI provides complementary information for the management of ischemic heart disease and has a higher sensitivity than Perf-MRI alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050238
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  • 7
    Electronic Resource
    Electronic Resource
    Diameter of the common bile duct in the elderly patient: measurement by ultrasound (1998)
    Springer
    European radiology 8 (1998), S. 1413-1415 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Bile duct ; Ultrasound studies ; Obstruction ; Normal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We wanted to assess the width of the common bile duct (CBD) in an asymptomatic elderly (〉 75 years) population, since no previous report has particularly considered the important age-related increase in CBD diameter for this patient group. CBD width of 92 asymptomatic people over 75 years of age (mean 84.7 years, range 75–96 years) without clinical or laboratory evidence for biliary, hepatocellular or pancreatic disease was measured by real-time high-resolution ultrasound of the upper abdomen. All examinations were performed by one experienced radiologist. Mean values were calculated for three groups: patients with and without cholecystolithiasis and after cholecystectomy. Statistical analysis was carried out by analysis of variance. Considering the measurements of all patients, the mean width (± SD) of the CBD was calculated as 6.5 ± 2.5 mm. The difference between patients without cholecystolithiasis (6.2 ± 2.3 mm) and patients after cholecystectomy (8.7 ± 2.9 mm) was statistically significant (P 〈 0.0001). Cholecystolithiasis (6.0 ± 1.6 mm) proves not to be an additional factor for CBD widening in comparison with patients without stone disease. The CBD of these very elderly subjects shows a considerable increase in comparison with the recommended borderline values in the ultrasound literature. An upper limit of 10 mm seems reasonable for patients with and without cholecystolithiasis. A significant increase in CBD width after cholecystectomy was found and measurements up to 14 mm may occur. Measurements have to be correlated with clinical and laboratory findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050563
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  • 8
    Electronic Resource
    Electronic Resource
    Clinical utility of contrast-enhanced MR angiography (1997)
    Springer
    European radiology 7 (1997), S. S178 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Magnetic resonance angiography ; Contrast media ; Pulmonary arteries ; Carotid arteries ; Renal arteries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. MR angiography (MRA) is a technique under ongoing discussion. Its non-invasiveness and sensitivity to flow irregularities make it an investigational technique which is easy to apply but which does not always lead to comprehensive results. It requires special skill to perform and also experience for correct interpretation of the results. The lengthiness of the procedure combined with certain physical properties tends to limit its use to mostly neurovascular applications. With the introduction of ultrafast MRA in conjunction with peripheral bolus-injection of extracellular contrast media, a new approach to the imaging of such regions as the thoracic and abdominal vasculature not to mention other vascular territories has become possible. In this paper, considerations of bolus and measurement optimization and timing protocols for dedicated indications are presented together with an overview on the experience acquired to date for CE-MRA of the carotid artery, mediastinal and pulmonary vessels, abdominal vasculature, and peripheral vessels. The main advantage of ultrafast CE-MRA is that patients are subjected to much more tolerable breath-hold investigations with the result that physiological motion such as peristalsis or major pulsation is minimised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006890
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  • 9
    Electronic Resource
    Electronic Resource
    MR angiography: supra-aortic vessels (1999)
    Springer
    European radiology 9 (1999), S. 1277-1284 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Magnetic resonance angiography ; Digital subtraction angiography ; Carotid artery disease ; Vertebral arteries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Magnetic resonance angiography (MRA) has become an imaging modality which comprises various techniques based on two concepts: methods relying on the natural flow effects, the time-of-flight and phase-contrast technique, either in two- or three-dimensional acquisition mode, and the more recently developed contrast-enhanced (CE) MRA methods. The main indications for evaluation of the supra-aortic vessels are, firstly, the grading of carotid artery stenoses caused by an atherosclerotic process, and secondly, the evaluation of dissections of the cervical arteries because this disease plays an important role as a cause for stroke especially in younger patients. The various MRA techniques in their application to the main pathologies encountered at the supra-aortic vessels are presented, and recent developments in the promising field of CE MRA are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050834
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  • 10
    Electronic Resource
    Electronic Resource
    Pitfalls and limitations of magnetic resonance imaging in chronic posttraumatic osteomyelitis (2000)
    Springer
    European radiology 10 (2000), S. 1815-1823 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Chronic posttraumatic osteomyelitis ; MR imaging ; CT ; Metal artefact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to evaluate pitfalls and technical limitations of MR imaging in diagnosing relapse of chronic posttraumatic osteomyelitis of the lower extremities. Retrospective analysis of MR examinations in 15 patients (17 body areas) with suspected relapse of chronic posttraumatic osteomyelitis (at least 1.5 years duration/mean number of surgical procedures per patient: 5.8). The MRI findings were compared with postoperative bacteriology (n = 11) and clinical follow-up (n = 4). Five patients had additional CT examination. Magnetic resonance imaging identified all infected areas correctly, but five uninfected regions were diagnosed false positive due to postoperative scarring/oedema in bone defects (n = 4) and soft tissue (n = 1). Specificity of MRI in diagnosing active bone infection was 63 % and sensitivity 100 %. Additional CT was preoperatively necessary in 5 patients (33 %) to further examine osteomyelitic and reparative bone remodeling. Metal artefacts were present in 11 patients, rendering complete evaluation impossible (n = 2) or considerably more difficult (n = 4). Scarring/oedema in postoperative bone defects occurs up to 13 months postoperatively and represents a major pitfall leading to low specificity. Definitive evaluation of suspected fistula, bony fragments and mineralization by MRI may be limited in this special patient group and requires additional CT in one third of patients. Metal artefacts occur in most patients and may impair or even prevent correct film evaluation in 23 and 11 %, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300000480
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