共查询到20条相似文献,搜索用时 62 毫秒
1.
M. Vahlensieck Ph. Lang K. Seelos D. Yang-Ho Sze S. Grampp M. Reiser 《Skeletal radiology》1994,23(8):607-608
The value of T2-weighted fast spin-echo imaging of the musculoskeletal system was assessed in 22 patients with various neoplastic,
inflammatory, and traumatic disorders. Images were acquired with high echo number (i.e., echo train length) fast spin-echo
(FSE; TR 2000 ms, effective TE 100 ms, echo number 13, lineark-space ordering), conventional spin-echo (SE; TR 2000 ms, TE 100 ms) and gradient-echo (GRE) sequences (TR 600 ms, TE 34 ms,
flip angle 25°). Signal intensities, signal-to-noise ratios, contrast, contrast-to-noise ratios, lesion conspicuousness, detail
perceptibility, and sensitivity towards image artifacts were compared. The high signal intensity of fat on FSE images resulted
in a slightly inferior lesion-to-fat contrast on FSE images. However, on the basis of lesion conspicuity, FSE is able to replace
time-consuming conventional T2-weighted SE imaging in musculoskeletal MRI. In contrast, GRE images frequently showed superior
lesion conspicuity. One minor disadvantage of FSE in our study was the frequent deterioration of image quality by blurring,
black band, and rippling artifacts. Some of these artifacts, however, can be prevented using short echo trains and/or short
echo spacings. 相似文献
2.
K Sugimura H Kawamitsu K Yoshikawa T Kasai K Yuasa T Ishida 《Nihon Igaku Hōshasen Gakkai zasshi. Nippon acta radiologica》1992,52(3):338-343
ECG-gated spin-echo imaging (ECG-SE) can reduce physiological motion artifacts. However, ECG-SE does not provide strong T1-weighted images because repetition time (TR) depends on heart rate (HR). We investigated the usefulness of low flip angle spin-echo imaging (LFSE) in obtaining more T1-dependent contrast with ECG gating. in computer simulation, the predicted image contrast and signal-to-noise ratio (SNR) obtained for each flip angle (0-180 degrees) and each TR (300 msec-1200 msec) were compared with those obtained by conventional T1-weighted spin-echo imaging (CSE: TR = 500 msec, TE = 20 msec). In clinical evaluation, tissue contrast [contrast index (CI): (SI of lesion-SI of muscle)2*100/SI of muscle] obtained by CSE and LFSE were compared in 17 patients. At a TR of 1,000 msec, T1-dependent contrast increased with decreasing flip angle and that at 38 degrees was identical to that with T1-weighted spin-echo. SNR increased with the flip angle until 100 degrees, and that at 53 degrees was identical to that with T1-weighted spin-echo. CI on LFSE (74.0 +/- 52.0) was significantly higher than CI on CSE (40.9 +/- 35.9). ECG-gated LFSE imaging provides better T1-dependent contrast than conventional ECG-SE. This method was especially useful for Gd-DTPA enhanced MR imaging. 相似文献
3.
MR imaging of the female pelvis at 3 Tesla: evaluation of image homogeneity using different dielectric pads 总被引:1,自引:0,他引:1
Kataoka M Isoda H Maetani Y Nakamoto Y Koyama T Umeoka S Tamai K Kido A Morisawa N Saga T Togashi K 《Journal of magnetic resonance imaging : JMRI》2007,26(6):1572-1577
PURPOSE: To evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads. MATERIALS AND METHODS: A total of eight healthy females were scanned using a 3T MR scanner equipped with a body-array coil. Axial and sagittal fast spin-echo T2-weighted images (T2WI) (TR/TE = 3200 msec/94 msec), axial fast spin-echo T1-weighted images (T1WI) (TR/TE = 700 msec/11 msec), and sagittal half-Fourier acquisition single-shot turbo spin-echo (HASTE) images (TR/TE = 3000 msec/100 msec) were performed for pelvic imaging. Sequences were repeated with dielectric pads (consisting of either ultrasound [US] gel or water), and without pads. Three or four regions of interest (ROIs) were placed on fatty tissues and the ratio of minimum to maximum signal intensity (RSI) was calculated as a marker of image homogeneity. RESULTS: RSI was significantly higher on T2WI and T1WI when using dielectric pads than when no pad was used. A similar tendency was observed in RSI on HASTE. No significant difference was found between images with US gel pads and those with water pads. CONCLUSION: Dielectric pads consisting of either US gel or water are effective in improving image homogeneity of the pelvis on 3T MRI. 相似文献
4.
P Pavone G Patrizio M S Giuliani N F De Stefano M M Laconi R Passariello 《La Radiologia medica》1991,81(5):605-608
Magnetic Resonance imaging of the upper abdomen was performed on more than 300 patients. The aim of the study was to determine the influence of spin-echo parameters on intrinsic image contrast. Different TR (ranging 260 to 2000 ms) and TE (ranging 20 to 120 ms) values were employed in two patients with a hepatic metastases and in a healthy volunteer with a hepatic cyst. The highest liver-to-lesion contrast was observed when the shortest TR and TE values (260 and 20 ms, respectively) were used, while the lesions appeared isointense with the surrounding parenchyma with TR 800 ms. In T2-weighted images TR 2000 ms allowed the complete recovery of longitudinal magnetization, giving a contrast relative only to the T2 of the lesion. 相似文献
5.
David W. Piraino Peter A. Hardy Jean P. Schils Bradford J. Richmond Jean A. Tkach George H. Belhobek 《Journal of magnetic resonance imaging : JMRI》1993,3(6):835-842
Conventional T2-weighted spin-echo magnetic resonance imaging of the knee requires a long TR. Fast spin-echo (FSE) imaging can improve acquisition efficiency severalfold by collecting multiple lines of k space for each TR. Compromises in resolution, section coverage, and contrast inevitably result. The authors examined the compromises encountered in FSE imaging of the knee and discuss the variations in image contrast and resolution due to choices of sequence parameters. For short TR/TE knee imaging, FSE does not appear to offer any advantages, since the increased collection efficiency for one section reduces the available number of sections, so that the total imaging time for a given number of sections remains constant relative to conventional spin-echo imaging. For T2-weighted images, considerable time can be saved and comparable quality images can be obtained. This saved time can be usefully spent on increasing both the resolution of the image and its signal-to-noise ratio, while still reducing total acquisition time by a factor of two. The preferred FSE T2-weighted images were acquired with a TR of 4,500 msec, TE of 120 msec, and eight echoes. The available number of sections is compromised, and the sequence remains sensitive to flow artifacts; however, the FSE sequence appears to be promising for knee imaging. 相似文献
6.
Naganawa S Koshikawa T Fukatsu H Ishigaki T Aoki I Ninomiya A 《AJNR. American journal of neuroradiology》2002,23(2):299-302
High-resolution MR imaging of the inner ear with a heavily T2-weighted 3D fast spin-echo sequence has been performed successfully at 1.5 T. However, at 3 T, the longer T1 time of CSF necessitates a longer TR, resulting in significantly prolonged imaging times. In this study, the fast recovery 3D fast spin-echo sequence, which permits the TR to be reduced while maintaining T2 contrast, was optimized at 3 T for imaging of the inner ear. The optimized sequence parameters are as follows: 1500/294 (TR/TE); echo spacing, 18.1 ms; bandwidth, 38 kHz at 512 readout; and imaging time, 13 minutes. 相似文献
7.
Objective To prospectively compare inversion recovery (IR) fast spin-echo (FSE) with T1-weighted spin-echo (SE) and T2-weighted chemical-shift
fat-saturated (FS) FSE magnetic resonance sequences in the detection of bone marrow abnormality. Design. Twenty-nine sets of T1-weighted SE [400–640/10–20 (TR/TE)], T2-weighted FS-FSE [2400–3800/91–112/8 (TR/TE/ETL)], and IR-FSE
[3700–6000/12–14/170/8 (TR/TE/T1/ETL)] images were acquired with a 1.5-T magnet in 27 patients with bone marrow lesions. The
visibility, margination, and extent of 41 lesions, image quality, contrast, and artifacts were qualitatively and quantitatively
compared. Results. The lesions were more conspicuous on the IR-FSE than on the T1-weighted SE and T2-weighed FS-FSE images. The extent of lesions
was similar for all three sequences. Image quality was better and there were fewer motion artifacts on the T1-weighted images.
The mean lesion contrast-to-noise ratio was significantly higher on the T1-weighted images (p<0.05). Conclusion. The IR-FSE sequence is highly sensitive for detecting bone marrow pathology, with scan time comparable to the T1-weighted
SE and T2-weighted FS-FSE sequences. 相似文献
8.
Dynamic magnetic resonance imaging in the assessment of chronic medical nephropathies with impaired renal function 总被引:8,自引:0,他引:8
Dalla-Palma L Panzetta G Pozzi-Mucelli RS Galli G Cova M Meduri S 《European radiology》2000,10(2):280-286
We examined the value of dynamic magnetic resonance imaging (MRI) in chronic renal disease with renal insufficiency. In 33
consecutive patients (21 vascular nephropathy, 12 glomerular nephropathy) MRI was performed using a 1.5-T unit and a body
coil, with SE T1-weighted (TR/TE = 600/19 ms) and dynamic TFFE T1-weighted sequences (TR/TE = 12/5 ms, flip angle = 25 °)
after manual bolus injection (via a cubital vein) of 0.1 mmol/kg Gd-DTPA-BMA. Morphological evaluation was performed in unblinded
fashion by three radiologists, evaluating renal size, cortical thickness, and corticomedullary differentiation. Functional
analysis was performed by one reviewer. Time-signal intensity curves, peak intensity value (P), time to peak intensity (T),
and the P/T ratio were obtained at the cortex, medulla, and pyelocaliceal system of each kidney. The relationship of these
parameters to serum creatinine and with creatinine clearance was investigated. A good correlation between morphological features
of the kidneys and serum creatinine values was found. Morphological findings could not distinguish between vascular and glomerular
nephropathies. A statistically significant correlation (P <0.01) between cortical P, cortical P/T, medullary P, and serum creatinine and creatinine clearance was found. A significant
correlation (P <0.01) was also found between cortical T, medullary P/T, T of the excretory system, and creatinine clearance. The cortical
T value was significantly higher (P <0.01) in vascular nephropathy than in glomerular nephropathy. Thus in patients with chronic renal failure dynamic MRI shows
both morphological and functional changes. Morphological changes are correlated with the degree of renal insufficiency and
not with the type of nephropathy; the functional changes seem to differ in vascular from glomerular nephropathies.
Received: 5 March 1999; Revised: 28 June 1999; Accepted: 9 August 1999 相似文献
9.
J. Mäurer M. Rausch W. S. Richter J. C. Böck H. J. Steinkamp T. J. Vogl R. Felix 《European radiology》1995,5(5):504-510
The purpose of this study was to evaluate the utility of a dynamic contrast enhanced FLASH-2D sequence for differential diagnosis of tumours in head and neck in 93 patients. Initially, the localization of the lesion and the selection of four representative slices for the dynamic study were obtained by a T2-weighted spin-echo sequence (TR 2000–3000 ms; TE 25/90 ms). After IV bolus injection of the contrast agent 10 images were acquired during a period of 3 min by a FLASH-2D sequence (TR 60 ms; TE 6 ms; flip angle 40° matrix 256 × 256; one acquisition). The percentage signal intensity (SI) increase (r) and the slope (S) of the curve were calculated on the basis of the SI time curve of the pathological lesion and of muscle. Inflammatory processes could be differentiated from malignant or benign tumours by means of a higher contrast enhancement. The time of the maximum SI was not specific for the different lesions. In comparison with muscle the maximum SI change was achieved earlier in a pathological process.
Correspondence to: J. Mäurer 相似文献
10.
Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results 总被引:1,自引:0,他引:1
The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral
joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradient-echo (GE) images were obtained (TR 32 ms, TE 10 ms, flip
angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45
ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE
96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared
with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences.
Received 24 May 1996; Accepted 30 August 1996 相似文献
11.
MRI gadolinium enhancement of bone marrow: age-related changes in normals and in diffuse neoplastic infiltration 总被引:5,自引:0,他引:5
Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse
malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group
2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast
signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI)
and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were
performed in 10 controls with normal bone marrow.
Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there
is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%)
diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted
SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is
dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed
with SI measurements. 相似文献
12.
Summary The variations of the relative signal intensity and the time dependent changing contrast of intracranial hemorrhages on high-field spin-echo magnetic resonance images (MRI) were studied in 28 pediatric patients. For T1-weighted images, a repetition time (TR) of 500 ms and an echo time (TE) of 30 or 23 ms was used. The corresponding times for T2-weighted images were TR 3000 ms and TE 120 ms. Intracranial hematomas, less than 3 days old, were iso- to mildly hypointense on short TR/TE scans and markedly hypointense on long TR/TE scans (acute stage). In the following four days the signal of the hematomas became hyperintense on short TR/TE scans, beginning in the periphery and proceeding towards the center. On long TR/TE scans the signal remained markedly hypointense (early subacute stage). 7–14 days old hematomas were of high signal intensity on short TR/TE scans. On long TR/TE scans they appeared hypointense in the center and hyperintense in the periphery (late subacute stage). By the end of the second week the hematomas were of high signal intensity on all pulse sequences (chronic stage). Chronic hematomas were surrounded by a parenchymal rim of hypointensity on long TR/TE scans. 28 neonates and infants (with 11 follow-up examinations) of 31.5–70.6 weeks postconceptional age (PCA), with an intracranial hemorrhage were examined. The etiologies of the hemorrhages were: asphyxia (17 cases), brain infarct (2), thrombocytopenia (1), clotting disorder (1) and unknown origin (7). The aim of this study was to describe the appearance of intracranial hemorrhages inneonates and infants with MRI at2.35 Tesla using spine-cho sequences. 相似文献
13.
Vanel Daniel Shapeero Lorraine G. Tardivon Anne Western André Guinebretière Jean Marc 《Skeletal radiology》1998,27(9):505-510
Objective. To report the application of dynamic contrast-enhanced subtraction MRI for detecting recurrences in aggressive or malignant
soft tissue tumors. Design. The imaging studies consisted of static (T1- and T2-weighted spin-echo) acquisitions, followed by dynamic conventional spin-echo
short TR/TE images (at 45 s, 1 min 30 s and 5 min) after a bolus of intravenous contrast medium. Contrast images were subtracted
from the precontrast scan on the console. Patients. Ninety-eight patients were studied who had had aggressive or malignant soft tissue tumors treated by surgery, and were followed
up to assess recurrences. Results. Subtraction MRI characterized recurrences better than routine sequences in 10 patients (1 lesion was seen only with this
technique, 6 were better delineated, and 3 inflammatory pseudotumors were identified), and less well in 4 cases. Conclusion. As the number of levels studied on dynamic images is limited, and all but one recurrence were detected on T2-weighted images,
it remains logical to start the examination with T2-weighted spin-echo images, and to use the dynamic study only if contrast
injection is required. 相似文献
14.
Imaging of pancreatic neoplasms: comparison of MR and CT 总被引:2,自引:0,他引:2
E Steiner D D Stark P F Hahn S Saini J F Simeone P R Mueller J Wittenberg J T Ferrucci 《AJR. American journal of roentgenology》1989,152(3):487-491
Thirty-two patients with pathologically proved pancreatic carcinomas or cystadenomas were evaluated with MR images obtained with T1-weighted spin echo (short TR/short TE), inversion recovery, and T2-weighted spin-echo (long TR/long TE) pulse sequences. CT was used as the reference standard to determine the ability of MR to delineate normal and abnormal pancreatic anatomy and thereby to exclude or detect pancreatic malignancy. Short TR/short TE spin-echo sequences were significantly better (p less than .05) than inversion recovery or T2-weighted spin-echo sequences in resolution of both normal and abnormal anatomy. Resolution of pancreatic anatomy correlated (r = .9) with the image signal-to-noise ratio. In seven (22%) of 32 cases, MR visualized pancreatic tumors better than CT did because it showed a signal intensity difference between the tumor and normal pancreatic tissue. Overall, the slight superiority of MR over CT for tumor visualization tended to occur in larger tumors and was not statistically significant. On T1-weighted images, 63% (20 of 32) of pancreatic tumors studied had lower signal intensities than normal pancreatic tissue, whereas on T2-weighted sequences (TE = 60, 120, and 180 msec) only 41% (13 of 32) of tumors had increased signal intensities. Currently available MR imaging techniques offer no significant advantages over CT for evaluating the pancreas for neoplasia. 相似文献
15.
R Chisin R B Buxton M W Ragozzino P A Beaulieu R L Fabian T J Brady 《AJNR. American journal of neuroradiology》1989,10(4):719-724
A new approach for producing primarily T2- and proton-density-weighted MR images in less time than the conventional long TR, long TE imaging is to reduce the TR of a double spin-echo pulse sequence and to also reduce the RF excitation flip angle to minimize the resulting T1 sensitivity. In preliminary studies with a human volunteer and five patients with various diseases of the head and neck, conventional long TR, long TE and short TR, short TE images were compared with short TR, long TE images with reduced flip angles (45 degrees, 30 degrees), which required only 40% of the imaging time of the long TR images. The latter images showed a similar contrast pattern to the conventional T2-weighted image, and contrast-to-noise measurements indicated an increase in contrast between the lesion and nearby tissue when the flip angle was reduced. Furthermore, the maximum contrast/noise per unit imaging time on the short TR, long TE image was comparable to that on the long TR, long TE image. Optimization of the flip angle with short TR allows a substantial reduction in imaging time but with a reduction in multislice capability. This technique will be most useful in areas of complex anatomy where two or more orthogonal imaging planes are required, such as the head and neck. 相似文献
16.
Three-dimensional fast recovery fast spin-echo imaging of the inner ear and the vestibulocochlear nerve 总被引:3,自引:0,他引:3
Nakashima K Morikawa M Ishimaru H Ochi M Kabasawa H Hayashi K 《European radiology》2002,12(11):2776-2780
The aim of this study was to assess the performance of three-dimensional fast recovery fast spin-echo (3DFRFSE) for imaging
of the inner ear as well as the facial and vestibulocochlear nerves. We evaluated 3DFRFSE sequences, comparing it with 3D
fast spin-echo (3DFSE) in a water phantom and in 12 normal volunteers. We also examined 66 patients using 3DFRFSE sequence
and assessed the visualization of their pathologies. In a water phantom study, signal intensity (SI) on 3DFRFSE was higher
than that on 3DFSE at the same TR ranging from 1500 to 6000 ms. In normal volunteers, 3DFRFSE with TR of 2800 ms showed comparable
SI, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) superior to those on 3DFSE with TR of 5000 ms. In clinical
setting, 3DFRFSE was useful in demonstrating anatomic details in the labyrinth and pathologic findings of inner ear. The 3DFRFSE
can provide high-resolution heavily T2-weighted images (T2WI) with shorter scan time than 3DFSE without significant disadvantage.
The 3DFRFSE is a beneficial technique for evaluation of lesions in the inner ear as well as the facial and vestibulocochlear
nerves.
Electronic Publication 相似文献
17.
Edwin van der Linden Herman M. Kroon Joost Doornbos J. Hermans Johan L. Bloem 《Skeletal radiology》1998,27(6):297-305
Objective. To identify an optimal pulse sequence for in vitro imaging of hyaline cartilage at 0.5 T. Materials and methods. Twelve holes of varying diameter and depth were drilled in cartilage of two pig knees. These were submerged in saline and
scanned with a 0.5-T MR system. Sixteen T1-weighted gradient echo (GE), two T2-weighted GE, and 16 fast spin echo sequences
were used, by varying repetition time (TR), echo time (TE), flip angle (FA), echo train length, profile order, and by use
of fat saturation. Contrast-to-noise ratios (CNR) of cartilage versus saline solution and cartilage versus subchondral bone
were measured. Cartilaginous lesions were evaluated separately by three independent observers. Interobserver variability and
correlation between the quantitative and qualitative analyses were calculated. Results. The mean CNRs of two specimens of cartilage versus saline solution ranged from 6.3 (±2.1) to 27.7 (±2.5), and those of cartilage
versus subchondral bone from 0.3 (±0.2) to 22.5 (±1.4). The highest CNR was obtained with a T1-weighted spoiled 3D-GE technique
(TR 65 ms, TE 11.5 ms, FA 45°). The number of lesions observed per sequence varied from 35 to 69. Observer agreement was fair
to good. The T1-weighted spoiled GE sequences with a TR of 65 ms, TE of 11.5 ms and FA of 30° and 45° were significantly superior
to the other 34 sequences in the qualitative analysis. Conclusion. T1-weighted spoiled 3D-GE sequences with a TR of 65 ms, a TE of 11.5 ms, and a FA of 30–45° were found to be optimal for
in vitro imaging of cartilage at 0.5 T. 相似文献
18.
Cieszanowski A Szeszkowski W Golebiowski M Bielecki DK Grodzicki M Pruszynski B 《European radiology》2002,12(9):2273-2279
The differentiation of hemangioma from other hepatic neoplasms using MRI usually relies on the evaluation of heavily T2-weighted images. The aim of this study was to assess the value of T2-relaxation times calculated from moderately T2-weighted turbo spin-echo (TSE) sequence in characterization of focal hepatic lesions, including hepatic malignancies, focal nodular hyperplasia (FNH), hemangioma, and cyst. Fifty-two patients with 114 proven lesions (61 malignant masses, 6 focal nodular hyperplasias, 28 hemangiomas, 19 cystic lesions) were examined on 1.5-T system using a double-echo TSE sequence (TR=1800 ms; TE(eff) 1=40 ms; TE(eff) 2=120 ms). Signal intensities (SI) of the liver as well as SI of all lesions were measured, and then the T2-relaxation times were calculated. The mean T2 time for the liver was 54 ms (+/-8 ms), for FNH 66 ms (+/-7 ms), for malignant hepatic lesions 85 ms (+/-17 ms), for hemangiomas 155 ms (+/-35 ms), and for cystic lesions 583 ms (+/-369) ms. Most malignant hepatic lesions were best differentiated between the thresholds of 67 and 116 ms, generating a sensitivity of 90% and a specificity of 94%. There were six false-negative diagnoses of malignant tumor and three false-positive cases (two hemangiomas and one FNH). Calculation of the T2-relaxation times obtained from the double-echo TSE sequence with moderate T2-weighting allowed differentiation between malignant and benign hepatic lesions with high sensitivity and specificity. 相似文献
19.
K Nakanishi M Inoue T Murakami K Tsuda T Mitani T Hashimoto S Maeshima K Tomoda S Hori H Nakamura 《Nihon Igaku Hōshasen Gakkai zasshi. Nippon acta radiologica》1992,52(12):1647-1652
To evaluate the diagnostic ability of MR imaging for plica synoviallis mediopatellaris (PSM), we retrospectively reviewed the MR imaging findings of patellofemoral space in 20 knee joints of 11 patients. In all 20 knee joints, arthroscopy and MR imaging were available. MR imaging was performed with a 1.5 Tesla Magnetom (Siemens) using a round surface coil. Pulse sequences were SE (TR 600 ms/TE 26 ms), SE (TR 200 ms/TE 26, 70 ms) and FLASH (TR 450 ms/TE 15 ms/FA 90 degrees). In six of the 20 knees with PSM proved by arthroscopy, a low intensity band was shown above the medial condyle of the femur on both T1- and T2-weighted MR images, and on FLASH images this band was shown as intermediate intensity. In the other 14 knees with no PSM observed by arthroscopy, the low intensity band was not shown on MR imaging. In all 20 knees, a similar low intensity band was shown about 1 cm cranial to the medial condyle of the femur. This should not be diagnosed as PSM. The low intensity band seen on T1- and T2-weighted MR images and its anatomical relation to the medial condyle are important in diagnosing PSM. 相似文献
20.
Contrast-enhanced MRI of periarticular soft-tissue changes in experimental arthritis of the rat 总被引:1,自引:0,他引:1
F Terrier D Revel C E Reinhold J Levine W Grodd H K Genant R C Brasch 《Magnetic resonance in medicine》1986,3(3):385-396
This study was to determine if manipulation of magnetic resonance signal intensity by means of an intravenously injected paramagnetic contrast agent is useful for the detection and characterization of periarticular inflammation. Arthritis was induced in 20 rats by means of intradermal injection of Freund's complete adjuvant. MR imaging was performed with a resistive magnet operating at 0.35 T. A double spin-echo technique with TE's of 28 and 56 ms and TR's of 0.5 and 2.0 s was used. The hindpaws of the adjuvant-injected rats were imaged on Day 8, Day 11, or Day 15 following injection of the adjuvant. The images were obtained in the transverse plane before and after intravenous injection of gadolinium-DTPA (0.2 mmol/kg). Because of their long T2 relaxation time, inflammatory lesions were characterized by high MR signal intensity on precontrast images obtained with long TR and long TE (T2-weighted images). On the other hand, because of their long T1 relaxation time, the inflammatory lesions were of relatively low intensity and not easily recognized on precontrast images obtained with short TR and short TE (T1-weighted images). Postcontrast T1-weighted images were also sensitive in detecting periarticular inflammation as a result of T1 shortening by the gadolinium-DTPA. However, in our particular model, the data did not indicate any greater MR sensitivity for detecting arthritis by means of gadolinium-DTPA enhancement. 相似文献