摘要:

AbstractImplementation of MR imaging of the breast as an extension of the existing imaging modalities in the diagnosis of breast cancer was evaluated in a university cancer center. MR imaging of the breast was performed in 54 patients, in whom the MR results were compared with the triple test (the combination of clinical examination, mammographic evaluation, and cytology) and the final histological diagnosis. MR imaging of the breast depicted 30 of the 33 malignancies (sensitivity, 91%). In two of the malignancies, the carcinoma was clinically and mammographically occult. For the three patients with a false‐negative MRI diagnosis, the conventional mammography showed suspicious clustered microcalcifications as a sign of in situ carcinoma. For seven patients, MR imaging of the breast incorrectly suggested the presence of a malignant lesion (specificity, 67%). To improve MR specificity, we perform MR‐guided ultrasonographic fine‐needle aspiration biopsy (FNAB). Although MR imaging of the breast is a highly sensitive examination, conventional x‐ray mammography remains the most efficient imaging modality in the diagnosis of breast cancer. In our patient population, MR imaging of the breast had additional value for women with mammographically dense breast tissue and especially for patients with clinical evidence of breast carcinoma that could not be detected with conventional diagnostic

ISSN:1053-1807    

DOI:10.1002/jmri.1880060602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractThis study demonstrates the appearance of small bowel tumors on MR images. Sixteen patients with tumors involving small bowel were studied by MRI. All tumors were proven with histopathology. Eleven patients had primary tumors of the small bowel, which included the following: four carcinoid tumors, three adenocarcinomas, two lymphomas, one leiomyosarcoma, and one leiomyoma. Five patients had recurrent or metastatic disease to small bowel: two patients had colon cancer, one patient had pancreatic cancer, one patient had uterine leiomyosarcoma, and one patient had chloroma (leukemia). MR examination included breath‐hold T1‐weighted spoiled gradient echo (all patients), immediate postgadolinium‐spoiled gradient echo (10 patients), and 2 to 4 minutes postgadolinium T1‐weighted, fat‐suppressed images (all patients). Tumor size, local extent, signal intensity, and enhancement features of tumor and adjacent tissue were determined. Tumor ranged in diameter from 1 to 9 cm (mean, 4.0 cm). Tumors had similar signal intensity to normal small bowel on precontrast images. Fourteen malignant tumors showed heterogeneous enhancement greater than adjacent bowel on gadolinium‐enhanced images. Tumor local extent was best shown on precontrast‐spoiled gradient‐echo images and postgadolinium T1‐weighted fat‐suppressed images. Image quality was most consistent on breath‐hold images. The results of this study show that small bowel tumors are demonstrable on MR images. Precontrast breath‐hold T1‐weighted spoiled gradient‐echo images and gadolinium‐enhanced fat suppressed images demonstra

ISSN:1053-1807    

DOI:10.1002/jmri.1880060603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractOn arterial‐dominant‐phase images in multisection dynamic MR imaging, early‐enhancing areas that are perfusion abnormalities rather than tumor deposit are sometimes encountered. The purpose of this article was to determine the frequency, location, and appearance of these hepatic parenchymal hyperperfusion abnormalities and to discuss possible causes of these abnormalities. Multisection dynamic MR images obtained in 415 patients with suspected hepatobiliary diseases were reviewed for the presence of hyperperfusion abnormalities. A total of 96 hyperperfusion abnormalities were identified in 88 (21%) of 415 patients. They were characterized from their shape, distribution, or location as lobar or segmental (n= 36 [38%]), subsegmental (n= 32 [33%]), or subcapsular (n= 28 [29%]) hyperperfusion abnormalities. Presumable etiologies were considered as follows: (a) compression, obstruction, or ligation of the portal vein; (b) siphoning effect by tumor; (c) aberrent cystic venous drainage; (d) percutaneous ethanol injection; (e) percutaneous needle biopsy; (f) rapid drainage by the subcapsular vein; or (g) cirrhosis or unknown. A significant percentage of patients had hepatic hyperperfusion abnormalities. Familiarity with these hyperperfusion abnormalities on multisection dynamic MR images is important to prevent false‐positive di

ISSN:1053-1807    

DOI:10.1002/jmri.1880060604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractWith the increasing use of lasers in surgical procedures, there is need for a noninvasive imaging modality to monitor laser–tissue interactions. MRI can be used readily for imaging human anatomy and holds the potential to map laser‐induced thermal injury. This study investigates high resolution T1‐weighted MR imaging of human aorta samples (in vitro) that have been damaged thermally using an argon ion laser and the corresponding histology. High resolution T1‐weighted MR images (voxel size, .156 × .156 × .700 mm) clearly detected residual thermal injury as areas of bright signal intensity. Effective localization of thermal injury was achieved by subtraction of preinjury and postinjury slices with pseudocoloring of positive and negative differences. The results may serve as a basis from which to guide future in viv

ISSN:1053-1807    

DOI:10.1002/jmri.1880060605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractThe objective of this study was to compare the accuracy of T2‐weighted fast‐spin‐echo (FSE) and intermediate‐weighted spin‐echo (SE) MR imaging in the detection of meniscal tears. Seventy‐six patients (152 menisci) who had arthroscopic surgery after MR imaging of the knee were studied. MR imaging included intermediate‐weighted SE and T2‐weighted FSE sequences. The use of intermediate‐weighted conventional SE images, T2‐weighted FSE images, and a combination of both sequences were evaluated in the detection of meniscal tears. T2‐weighted FSE imaging was slightly less accurate than intermediate‐weighted SE imaging in the diagnosis of meniscal tears. Interpretation of the menisci using both intermediate‐weighted SE and T2‐weighted FSE imaging did not improve the accuracy over intermediate‐weighted i

ISSN:1053-1807    

DOI:10.1002/jmri.1880060606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractThe MR appearance of clots with different internal structures was compared on gradient‐echo (GE) and spin‐echo (SE) images. After MR imaging, clots were submitted for histological analysis to allow direct correlation of clot structure with MR image intensity. Normal heterogeneous clots (containing entrapped serum) were hypointense compared to both unclotted blood (Hct 45) and brain on GE MR images. Homogeneous (serum‐poor) clots and settled blood were hyperintense to unclotted blood and isointense or hyperintense to brain. These results indicate that the GE technique is quite sensitive to the physical inhomogeneity created (at the voxel level) when blood forms an inhomogeneous clot containing relatively large islands of red blood cells (RBCs) surrounded by lakes of serum. The effect of the different possible clot structures on GE signal intensity thus provides an etiology for the previously unexplained observations of hemorrhage with high signal intensity on GE MR i

ISSN:1053-1807    

DOI:10.1002/jmri.1880060607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractTwenty‐one MRI studies with a fat‐suppression three‐dimensional spoiled gradient‐recalled echo in a steady state (3D SPGR) pulse sequence after intravenous contrast injection were evaluated to assess the accuracy in depicting chondromalacia of the knee. On the basis of MR images, chondromalacia and its grade were determined in each of five articular cartilage regions (total, 105 regions) and then the results were compared to arthroscopic findings. The sensitivity, specificity, and accuracy of MRI were 70%, 99%, and 93%, respectively. MR images depicted 7 of 11 lesions of arthroscopic grade 1 or 2 chondromalacia, and seven of nine lesions of arthroscopic grade 3 or 4 chondromalacia. The cartilage abnormalities in all cases appeared as focal lesions with high signal intensity. Intravenous contrast‐injection, fat‐suppression 3D SPGR imaging showed high specificity in excluding cartilage abnormalities and may be considered as an alternative to intra‐articular MR arthrography when chondromalacia

ISSN:1053-1807    

DOI:10.1002/jmri.1880060608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractCanavan's disease is an autosomal recessive hereditary leukodystrophy resulting from deficiency of the enzyme aspartoacylase. Two children suffering from this metabolic brain disease were examined using image‐guided localized proton spectroscopy. The absolute concentrations of metabolites were determined. These data demonstrate, for the first time, that the well known increase of the N‐Acetylaspartic acid (NAA)/Cho ratio in this disease may be not only due to a reduction of choline‐containing compounds in brain tissue but, at least in specific cases, also due to an increase of the NAA concentration, which is a result of the enzyme d

ISSN:1053-1807    

DOI:10.1002/jmri.1880060609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractWe have developed a novel algorithm to register three‐dimensional MR images that have undergone rigid body motion. The most interesting feature of the algorithm is that it reduces a general three‐dimensional rotation to a simple planar rotation by finding the axis of rotation. The algorithm, which is a nontrivial three‐dimensional extension of existing Fourier registration algorithms, has been tested on 30 artificially misaligned MR images of a phantom, four artificially misaligned MR images of a brain, and one case of actual patient motion. The algorithm successfully registered every image. The registration error for a voxel 10 cm from the origin for the artificially misaligned phantom images was 2.8 mm at most and had a mean of 1.2 mm and standard deviation of .7 mm. The registration parameters for the images contaminated by actual patient motion were similar to that from an established image registration algorithm. The results indicate that the algorithm is accurate, reliable, and fast. The rigid body model requires the brain to be segmented from MR images of the head before registr

ISSN:1053-1807    

DOI:10.1002/jmri.1880060610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractUsing a T1‐weighted hybrid rapid acquisition with relaxation enhancement (RARE) MR sequence that implements an echo‐to‐view mapping scheme termed “low‐high profile order,” we evaluated signal intensity changes in different brain tissues as a function of number of slices, interslice gap, and echo train length (ETL). We also measured phase‐encode and frequency‐encode noise as well as blurring artifacts along the phase‐encode direction as a function of ETL. Off‐resonance magnetization transfer effects were demonstrated to be responsible for signal intensities changes in white matter and gray matter when using multislice techniques. These effects are amplified by increasing the number of slices and ETL. Due to the nature of the implemented echo‐to‐view mapping scheme, no on‐resonance magnetization transfer effects were observed from the intraslice echo train. Selective background (white matter and gray matter) suppression in multislice T1‐weighted hybrid RARE, secondary to off‐resonance magnetization transfer effects, may provide better contrast resolution of enhancing central nervous system (CNS) lesions at much shorter scan time as compared to conventional spin‐echo T1‐weighted sequences. This improvement in contrast resolution as a function of ETL may be limited by worsening phase‐

ISSN:1053-1807    

DOI:10.1002/jmri.1880060611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY