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1.
The objective of this study was to compare the image quality, sensitivity, specificity, and diagnostic accuracy of an open
low-field MR system (0.2 T) with a standard high-field MR system (1.5 T) after arthrography of the shoulder. Thirty-eight
patients either with suspected chronic instability (n = 12) or rotator cuff abnormalities (n = 26) were examined. Intra-articular injection of diluted Gd-DTPA was followed in randomized order either first by imaging
on an open 0.2-T system or on a 1.5-T system. The image material was evaluated independently by two radiologists in a blinded
fashion with respect to overall image quality and the detection of rotator cuff as well as capsular and labral abnormalities.
Surgical correlation was available in 27 (71 %) of 38 patients. For both systems, sensitivity and specificity for rotator
cuff tears were 100 % each, and for labrum pathologies, these values were 100 and 93 %, respectively. The agreement for detection
of labral pathologies between low-field and high-field examinations was good (ϰ = 0.69, ϰ = 0.61). For the detection of full-thickness tears of the rotator cuff, the agreement between the low-field and high-field
MR examinations was very good and significant (ϰ = 0.94, ϰ = 1, p < 0.001). Overall image quality was rated good in 17 (45 %) and fair in 21 (55 %) of 38 cases on the 0.2-T MR system, and
good in 32 (84 %) and fair in 6 (16 %) of 38 cases on the 1.5-T system. Motion artifacts were considered low in 24 (63 %)
and moderate in 14 (37 %) of 38 cases for the 0.2-T system and low in 34 (89 %) and moderate in 4 (11 %) for 1.5-T system.
Based on our results, low-field MR compares favorably to high-field MR in the detection of major abnormalities of the glenohumeral
joint, at least when MR arthrography is used. Disadvantages are the duration of the examination and thus the risk of reduced
image quality caused by motion artifacts.
Received: 14 July 1999; Revised: 27 December 1999; Accepted: 27 December 1999 相似文献
2.
MRI of peripheral joints with a low-field dedicated system: A reliable and cost-effective alternative to high-field units? 总被引:2,自引:0,他引:2
In the age of health care cost containment new imaging technology has to meet diagnostic requirements as well as economic limitations. In the MR sector new dedicated systems promise reliable diagnostic information at considerably lower costs than whole-body imagers. Within the past 18 months we have examined 2200 patients with acute and chronic lesions of peripheral joints (knee, ankle, foot, elbow, wrist, hand) in a 0.2T dedicated MR system (ARTOSCAN, Esaote Biomedica, Genoa, Italy). We report our experience with this system focusing on its special features, cost-effectiveness and on diagnostic accuracy of low-field MR studies of the knee in correlation with arthroscopy and in comparison with high-field whole-body imagers.
Correspondence to: B. Kersting-Sommerhoff 相似文献
3.
As low-field MR imaging is becoming a widely used imaging technique, we aimed at a prospective assessment of differences in imaging quality between low- and high-field MR imaging in multiple sclerosis patients possibly interfering with diagnostic or therapeutic decision making. Twenty patients with clinically proven multiple sclerosis were examined with optimized imaging protocols in a 1.5- and a 0.23-T MR scanner within 48 h. Images were assessed independently by two neuroradiologists. No statistically significant interrater discrepancies were observed. A significantly lower number of white matter lesions could be identified in low-field MR imaging both on T1- and on T2-weighted images (T2: high field 700, low field 481; T1: high field 253, low field 177). A total of 114 enhancing lesions were discerned in the high-field MR imaging as opposed to 45 enhancing lesions in low-field MR imaging. Blood-brain barrier disruption was identified in 11 of 20 patients in the high-field MR imaging, but only in 4 of 20 patients in low-field MR imaging. Since a significantly lower lesion load is identified in low-field MR imaging than in high-field MR imaging, and blood-brain barrier disruption is frequently missed, caution must be exercised in interpreting a normal low-field MR imaging scan in a patient with clinical signs of multiple sclerosis and in interpreting a scan without enhancing lesions in a patient with known multiple sclerosis and clinical signs of exacerbation. 相似文献
4.
W W Orrison G K Stimac E A Stevens D L LaMasters M C Espinosa L Cobb F A Mettler 《Radiology》1991,181(1):121-127
To assess objectively the sensitivity and specificity of low-field-strength (0.064 T) magnetic resonance (MR) imaging, a prospective blind study of 280 examinations was performed to compare low-field-strength MR imaging with computed tomography (CT) and with high-field-strength (1.5-T) MR imaging of the cranium. The sensitivity (defined as the true-positive rate) with high-field MR imaging was superior to that with low-field MR imaging and CT in helping detect overall abnormalities. Sensitivities were generally similar over a broad range of specific cranial central nervous system diseases. Low-field and high-field MR imaging were equivalent in the blind diagnoses of neoplasms and white matter disease, whereas low-field MR and CT were equivalent in the blind diagnoses of contusion, subdural and epidural hematoma, sinus disease, normality, and abnormality. The specificities with low-field MR imaging and CT were substantially better than those with high-field MR imaging. 相似文献
5.
MRI is increasingly being used as an interventional tool in neurosurgery. The field strength of “intraoperative” MR systems
is usually lower than that of imagers commonly used for diagnostic purposes. However, lesion enhancement and apparent lesion
extent depend on field strength. The aim of this study was to compare the contrast between intracranial, contrast-enhancing
space-occupying lesions and the surrounding white matter obtained with low-field (0.2 T) and high-field (1.5 T) MR imaging
and to find the contrast medium dosage for low-field MRI that produces the same lesion-to-white-matter contrast as the one
obtained with high-field MRI after the administration of a standard dose of the contrast medium. A total of 38 patients with
intracranial metastases or high-grade glioma were enrolled in this study. T1-weighted spin-echo sequences were acquired. High-field
(1.5 T) studies were performed after the i. v. administration of 0.1 mmol gadolinium-DTPA /kg body weight. For low-field MRI
(0.2 T) a dose escalation technique was used. T1-weighted sequences were repeated after each of three i. v. injections of
0.1 mmol gadolinium-DTPA/kg body weight. Thus, at the low-field examinations three T1-weighted sequences with a contrast medium
dosage of 0.1, 0.2 and 0.3 mmol gadolinium-DTPA /kg body weight were obtained. Lesion-to-white-matter contrasts were calculated
and compared. The average lesion-to-white-matter contrast obtained with high-field MR examinations was 1.63 (standard deviation
0.32). In the low-field MR examinations the average lesion-to-white-matter contrast was 1.34 (0.2) after a single dose, 1.57
(0.2) after a double dose, and 1.71 (.19) after a triple dose of contrast medium. The lesion-to-white-matter contrast of the
high-field MR examination after a single dose of contrast medium was significantly higher than that of the low-field study
after a single dose (P < 0.0001), but did not differ significantly from the low-field studies after a double (P = 0.28) or a triple dose (P = 0.17) of contrast medium. In a series of patients with contrast-enhancing space occupying brain lesions low-field MRI (0.2
T) after a double dose of contrast medium yielded the same lesion-to-white-matter contrasts as high-field MRI (1.5 T) after
a standard dose. This is an important finding to avoid errors in intraoperative MRI due to the immanently lower degree of
lesion enhancement in low-field MR imaging.
Received: 14 September 1999 Accepted: 15 February 2000 相似文献
6.
H. Bonél A. Frick H. Sittek A. Heuck M. Steinborn R. G. H. Baumeister M. Reiser 《Der Radiologe》1997,37(10):785-793
Summary
Purpose of this study was to evaluate the diagnostic value of a low field dedicated MRI system in hand and wrist imaging.
All 308 exams of the hand and wrist, that were performed on a low-field dedicated MRI system (Artoscan, Esaote Biomedica,
Italy) in our institution in 1996, and high-field MRI exams performed in addition as part of the diagnostic work-up, were
evaluated and correlated to final operative (n = 64) and histologic (n = 12) reports. 90 % of all low-field MRI scans stated a diagnosis according to clinical suspicion. In 62 % the clinical question
was answered, and in 26 % additional pathologies were identified. An MR-diagnosis completely different from the clinical suspicion
was stated in 2 %. High field exams contributed additional information in 6 of 36 patients. In 3 patients a tumor was not
shown completely in the limited field-of-view of the dedicated low-field MRI-system. Frequency-selective fat-suppression pulse
sequences and a better spatial resolution were the reasons for the additional information obtained in the other three patients.
Low-field dedicated MR-imaging is a valuable method in the extensive work-up of the hand and wrist. Osseous, ligamentous and
tendinous pathologies are well depicted. Large or infiltrative tumors should be referred to a high-field system.
相似文献
7.
Gleno-humeral instabilities 总被引:4,自引:1,他引:3
The purpose of this review is to highlight the most efficient imaging exploratory techniques depicting shoulder instability,
to describe its various forms and to point out the findings which can simulate instability. In anterior recurrent dislocation,
surgery is indicated and the procedure essentially depends on the importance of glenoid rim lesions. In this case, a standard
X-ray evaluation is usually sufficient. The CT arthrography or MRI techniques give more specific details as to the severity
of the lesions, particularly soft tissues alterations; however, these data do not alter standard therapeutic protocol. In
fixed posterior dislocations, CT scan represents the most pertinent technique to evaluate the size of the humeral head defect
and to determine the therapeutic follow-up. In subtle forms of instability, diagnosis or instability direction are not clearly
assessed clinically and standard X-ray evaluation is usually unremarkable. In this case, further exploration, such as CT arthrography,
MR imaging or MR arthrography, are recommended to confirm the diagnosis of instability and to evaluate its direction. The
technique of choice is undoubtedly MR arthrography. Atraumatic voluntary painless subluxations associated with hyperlaxity
of the shoulder do not require any specific exploratory method because the findings are generally limited to a capacious axillary
pouch.
Received: 28 September 1998; Revised: 21 January 1999; Accepted: 22 March 1999 相似文献
8.
The aim of this study was to determine the accuracy in quantifying right and left ventricular volumes using a 1.0-T system
and commercially available, standard equipment. For exact comparison of MRI measurements and real volumes we used an animal
heart model ex vivo. Eight pig hearts were explanted and prepared by removal of the atria. Aorta and pulmonary truncus were
cannulated. Definable volumes were injected into the ventricles. Magnetic resonance imaging was performed at 1.0 T (Gyroscan
T10 NT, Philips, Eindhoven, The Netherlands); sequence: fast field echo–echo planar (multishot EPI); body coil; MR software:
Cardiac Application Package (Philips). Statistical analysis correlated the real volumes and MR measurements separately for
both ventricles and two investigators (SAS, ANOVA). For both ventricles and both investigators the correlation between real
volumes and MR measurements was greater than 0.99. There was no significant systematic false estimation for both ventricles.
Magnetic resonance imaging at 1.0 T using standard hardware and software equipment enables the quantification of right and
left ventricular volumes with high approximation to the real volumes in vitro. There is a clear restriction in translating
these data into a clinical application because under experimental conditions no motion-induced artifacts existed.
Received: 22 July 1999; Accepted: 27 August 1999 相似文献
9.
Rectal tumour staging: MR imaging using pelvic phased-array and endorectal coils vs endoscopic ultrasonography 总被引:5,自引:0,他引:5
Blomqvist L Machado M Rubio C Gabrielsson N Granqvist S Goldman S Holm T 《European radiology》2000,10(4):653-660
The aim of this study was to compare MR imaging and endoscopic ultrasonography (EUS) for the local staging of rectal tumours.
Forty-nine patients were examined on a 1.5-T MR unit using either a pelvic phased-array coil (n = 37) alone or combined with an endorectal coil (n = 12). Sagittal and axial sequences with T2-weighted fast spin-echo and axial T1-weighted spin-echo techniques were employed.
The EUS technique was performed using a flexible endosonoscope. The results were compared with findings at histopathological
sectioning of the specimen. The T-stage on MR correlated with histopathology in 32 of 49 patients and on EUS in 29 of 49 patients.
The N-stage on MR correlated with histopathology in 22 of 49 patients and on EUS in 26 of 49 patients. Tumour penetration
of the rectal wall was predicted by MR with 86 % sensitivity and 65 % specificity, and by EUS with 89 % sensitivity and 33
% specificity. Preoperative radiotherapy was administered to 40 of the patients after the examinations which may explain some
of the overstaging by MR and EUS. Three patients with surgically and histopathologically confirmed invasion of neighbouring
organs in the pelvis were detected preoperatively on MR but none on EUS. Tumour penetration of the rectal wall and local lymph
node metastases cannot accurately be predicted with MR or EUS. Magnetic resonance, however, seems to be more useful for preoperative
identification of clinically occult advanced disease.
Received: 18 February 1999; Revised: 17 September 1999; Accepted: 20 September 1999 相似文献
10.
Mediastinal myelolipoma: CT and MRI appearances 总被引:1,自引:0,他引:1
Kawanami S Watanabe H Aoki T Nakata H Hayashi T Kido M Tsukada J Eto S 《European radiology》2000,10(4):691-693
A 72-year-old man presented with a mediastinal mass on chest radiograph. Computed tomography and MR imaging showed that the
mass consisted of both fatty and small nodular soft tissue components, highly suggestive of an extramedullary hematopoiesis
or a myelolipoma. A CT-guided needle biopsy was next performed and confirmed the diagnosis. We discuss the CT and MR imaging
appearances of this tumor and usefulness of a CT-guided needle biopsy to avoid surgery in asymptomatic patients.
Received: 8 March 1999; Revised: 23 June 1999; Accepted: 25 June 1999 相似文献
11.
Savnik A Amris K Røgind H Prip K Danneskiold-Samsøe B Bojsen-Møller F Bartels EM Bliddal H Boesen J Egund N 《European radiology》2000,10(10):1655-1659
Falanga is an ancient form of punishment or torture but is still commonly reported by our refugees. The late result of caning
the heel and ball of the foot is a chronic painful condition with few clinical signs. The aim of the present study was to
assess, by MRI, possible morphologic characteristics of the heel and ball of the foot, related to falanga and pain in correlation
to clinical findings. Magnetic resonance imaging of the foot was obtained in 12 victims exposed to falanga torture and 9 healthy
volunteers. Sagittal T1-weighted spin-echo images (TR 616–840 ms, TE 20 ms), T2-weighted spin-echo images (TR 1900 ms, TE
90 ms), and short tau inversion recovery (STIR) images (TR 1200 ms, TE 15 ms, TI 100 ms) were performed. The central portion
of the plantar aponeurosis was generally significantly thicker in victims exposed to falanga torture as compared with that
of controls (P < 0.05). In all except one of the victims, MRI demonstrated two layers of the thickened plantar aponeurosis: a deeper portion
with normal homogeneous low signal intensity (SI) appearance, and a superficial layer with characteristic areas of mixed SI
on both T1- and T2-weighted images. There were no signs of chronic muscular compartment syndromes, and the thickness of the
plantar pad did not differ between the two groups. Magnetic resonance imaging may demonstrate morphologic characteristics
of the plantar aponeurosis which may confirm falanga torture. Further imaging with more specific sequences is warranted to
demonstrate the supposed injuries in the compartmental fat tissue chambers and the vascularity of the ball pad of the foot.
Received: 25 November 1999; Revised: 8 February 2000; Accepted: 6 April 2000 相似文献
12.
13.
Magnetic resonance imaging in the assessment of urologic disease: an all-in-one approach 总被引:9,自引:0,他引:9
Verswijvel GA Oyen RH Van Poppel HP Goethuys H Maes B Vaninbrouckx J Bosmans H Marchal G 《European radiology》2000,10(10):1614-1619
The aim of this study was to evaluate an “all-in-one” MR procedure to examine the kidneys, the renal vascular supply and
renal perfusion, and the urinary tract. In 64 patients (58 with urologic disease and 6 healthy volunteers), MR was performed
including: (a) T1- and T2-weighted imaging; (b) 3D contrast-enhanced MR angiography (MRA), including the renal arteries, renal
veins, as well as renal perfusion; and (c) 3D contrast-enhanced MR urography (MRU) in the coronal and sagittal plane. For
the latter, low- and high-resolution images were compared. Prior to gadolinium injection, 0.1 mg/kg body weight of furosemide
was administered intravenously. The results were compared with correlative imaging modalities (ultrasonography, intravenous
urography, CT), ureterorenoscopy and/or surgical–pathologic findings. Visualization of the renal parenchyma, the vascular
supply, and the collecting system was adequate in all cases, both in nondilated and in dilated systems and irrespective of
the renal function. One infiltrating urothelial cancer was missed; there was one false-positive urothelial malignancy. Different
MR techniques can be combined to establish an all-in-one imaging modality in the assessment of diseases which affect the kidneys
and urinary tracts. Continuous refinement of the applied MR techniques and further improvements in spatial resolution is needed
to expand the actual imaging possibilities and to create new tracts and challenges in the MR evaluation of urologic disease.
Received: 27 September 1999; Revised: 20 January 2000; Accepted: 22 May 2000 相似文献
14.
The aims of this article are to describe the findings of perividian tumor spread and to compare the accuracy of MRI and CT
in diagnosing perineural metastasis along the vidian nerve. Moreover, the frequency of perividian metastasis in patients with
head and neck cancer was evaluated. The CT and MR examinations of 98 consecutive untreated patients with histologically proven
head and neck cancer were retrospectively reviewed. We considered as criteria for perineural tumor spread along the vidian
nerve the following CT and MR findings: For CT (a) enlargement of the pterygoid canal, (b) erosion of its bony wall, and (c)
obliteration of its normal fatty content; and for MR (a) enlargement of the vidian nerve, (b) enhancement of the nerve, and
(c) obliteration of fat, particularly in the anterior part of the pterygoid canal. Ten patients met the selected criteria
for perineural metastasis, which was bilateral in 3 patients, with a total of 13 vidian metastases. The CT scans demonstrated
unilateral involvement of the vidian nerve in 9 patients. The MRI scans showed 13 perineural metastases. In 3 patients MR
scans demonstrated involvement of four vidian nerves that appeared normal on CT examinations. The diagnostic difference between
CT and MRI was statistically significant (Fisher's exact test; p = 0.04). Perineural spread along the vidian nerve is an event more frequent than previously reported and must be investigated
with a careful imaging technique. Although a major limitation of our study is the lack of histological proof, the MR finding
of a significant enhancement of the nerve, whether enlarged or normal in size, could be considered very suggestive of this
kind of metastatic spreading, particularly if associated with simultaneous involvement of the neighboring structures (pterygopalatine
fossa, foramen lacerum, trigeminal branches, etc.).
Received: 5 January 1999; Revision received 11 May 1999; Accepted: 17 June 1999 相似文献
15.
The objective of this study was to demonstrate the statistical significance of a reversed oblique radiograph of the foot
in patients with ankle or foot trauma. In 100 consecutive patients a reversed oblique radiograph of the foot was taken in
addition to the conventional plain films. Ten of 29 fractures were not visualised on the conventional films of foot and ankle
and could only be diagnosed on the reversed oblique film. In 7 of these 10 cases an avulsion fracture at the anterolateral
aspect of the calcaneus was present. This additional reversed oblique film of the foot seems to be of considerable importance,
especially when an anterolateral avulsion fracture of the calcaneus is clinically suspected.
Received: 1 December 1998; Revision received: 9 June 1999; Accepted: 14 July 1999 相似文献
16.
The role of MR imaging in invasive cervical carcinoma 总被引:6,自引:0,他引:6
In this article the role of MR imaging in the management of cervical cancer is reviewed and illustrated. The appearance of
the normal uterine cervix and of cervical carcinoma is shown. Important factors for optimal MR imaging of cervical carcinoma
are reviewed. The value of MR imaging in the staging of cervical carcinoma is illustrated by showing parametrial invasion
and lymph node involvement. Finally, the value of MR imaging staging is compared with clinical staging, CT staging, and surgical
findings. The role of new imaging techniques, such as fast dynamic enhanced MR imaging, is described.
Received: 12 April 1999; Revised: 13 July 1999; Accepted: 14 July 1999 相似文献
17.
Multifocal nodular fatty infiltration of the liver mimicking metastatic disease on CT: imaging findings and diagnosis using MR imaging 总被引:1,自引:0,他引:1
Kröncke TJ Taupitz M Kivelitz D Scheer I Daberkow U Rudolph B Hamm B 《European radiology》2000,10(7):1095-1100
The aim of this study was to describe the MR appearance of multifocal nodular fatty infiltration of the liver (MNFIL) using
T1-weighted in-phase (IP) and opposed-phase (OP) gradient-echo as well as T2-weighted turbo-spin-echo sequences with fat suppression
(FSTSE) and without (HASTE). Magnetic resonance imaging examinations at 1.5 T using T1-weighted IP and OP-GRE with fast low
angle shot (FLASH) technique, and T2-weighted FSTSE, T2-weighted HASTE of 137 patients undergoing evaluation for focal liver
lesions were reviewed. Five patients were identified in whom CT indicated metastatic disease; however, no liver malignancy
was finally proven. Diagnosis was confirmed by biopsy (n = 3), additional wedge resection (n = 1) or follow-up MRI 6–12 months later (n = 5). Regarding the identified five patients, the number of focal liver lesions was 2 (n = 2) and more than 20 (n = 3). The MR imaging characteristics were as follows: OP-image: markedly hypointense (n = 5); IP image: isointense (n = 2) or slightly hyperintense (n = 3); T2-weighted FSTSE-image: isointense (n = 5); T2-weighted HASTE image isointense (n = 1); slightly hyperintense (n = 4). On OP images all lesions were sharply demarcated and of almost spherical configuration (n = 5). Further evaluation by histology or follow-up MR imaging did not give evidence of malignancy in any case. Histology
revealed fatty infiltration of the liver parenchyma in three patients. Magnetic resonance follow-up showed complete resolution
in two patients and no change in three patients. Multifocal nodular fatty infiltration can simulate metastatic disease on
both CT and MR imaging. The combination of in-phase (IP) and opposed-phase (OP) gradient-echo imaging can reliably differentiate
MNFIL from metastatic disease.
Received: 15 September 1999 Revised: 3 February 2000; Accepted: 7 February 2000 相似文献
18.
This pictorial review illustrates the anatomical features of normal intra-articular components of the hip and their common
disorders on MR arthrography. On T1-weighted MR arthrograms, the normal contrast-filled joint cavity shows a homogeneous high
signal intensity. Normal acetabular labrum appears as a well-delineated triangle showing a low signal intensity, surrounded
by contrast material in the perilabral recess. Intra-articular paramagnetic contrast outlines labral tears, loose bodies,
communicating labral cysts and cartilage lesions (traumatic tears, focal defects, degenerative fissures and thinning), and
improves their detection. Overall, MR arthrography enables accurate detection and staging of hip intra-articular structure
abnormalities.
Received: 6 June 1998; Revision received: 2 January 1999; Accepted: 2 April 1999 相似文献
19.
Compressive vertebral haemangiomas (VHs) are rare. Correct preoperative diagnosis is useful both for operative planning (since
compressive VHs are extremely vascular lesions) and to allow preoperative embolisation. Numerous radiological signs for VHs
have been described, but compressive VHs frequently have atypical features. In particular, magnetic resonance features are
not well established. We present imaging features in three cases of compressive VH and review the imaging findings in an additional
106 previously published cases. Findings were typical in 52 of 80 plain film (65 %), 33 of 41 computed tomography (80 %) and
13 of 25 magnetic resonance examinations (52 %). The prevalence of previously described imaging features is reported. Awareness
of the range of magnetic resonance features is important since this is frequently the initial investigation in patients presenting
with symptoms of neural compression. Since computed tomography is typical in 80 % of cases, this is a useful confirmatory
test if magnetic resonance features are suspicious but not diagnostic of compressive VH.
Received: 6 August 1999; Revised: 4 November 1999; Accepted: 4 November 1999 相似文献
20.
The purpose of this study was to determine the value of MR imaging for the demonstration of masses in the tongue and floor
of the mouth. Nine patients were prospectively examined with MR imaging after physical examination. Imaging protocol included
T2 and contrast-enhanced and non-contrast-enhanced T1-weighted turbo spin-echo sequences, and the findings were compared with
surgical and histopathological results. Histopathological examination revealed four squamous cell carcinomas, one adenoid
cystic carcinoma, two tongue abscesses, and one chronic inflammatory change. The other case was diagnosed as hemangioma depending
on clinical and imaging findings alone. In cases with squamous cell carcinoma, staging was done on the basis of MR imaging
findings, and was found to be T4 in two cases, T3 in one case, and T2 in another. The primary role of MR imaging of the tongue
and oropharynx is not to make a tissue diagnosis. Multiple deep biopsies are mandatory for the differentiation of other inflammatory
and neoplastic lesions. Magnetic resonance imaging produces coronal and sagittal image planes to assess the volume and spread
of the lesion and helps the surgeon determine the direction in which the biopsy should be performed.
Received: 4 October 1999; Revised: 31 January 2000; Accepted: 6 April 2000 相似文献