ISSN:1053-1807    

DOI:10.1002/jmri.1880060202

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe purpose of this study is to compare sensitivity and specificity of helical CT and MR imaging for detecting acute pulmonary embolism (PE). Patients who were suspected clinically of having PE were randomly assigned to undergo either helical contrast‐enhanced CT or gradient‐echo MR (if one modality was contraindicated, the patient was assigned to the other). Patients were considered to have PE if they had: (1) high‐probability V‐Q scan and high clinical probability of PE; or (2) pulmonary angiogram positive for PE. Patients were considered not to have PE if they had either: (1) normal V‐Q scan; (2) low probability V‐Q scan and low clinical probability of PE; or (3) pulmonary angiogram negative for PE. The CT and MR images were read randomly and independently by five radiologists with varying levels of CT and MR experience. Twenty eight patients underwent CT and 25 MR. A total of 21 patients underwent pulmonary angiography (6 had PE, 15 did not have PE). Of the other 32 patients, 15 had high probability scan/high clinical probability and 17 had low probability scan/low clinical probability. For the five observers, the average sensitivity of CT was 75% and of MR 46%; the average specificity of CT was 89% and of MR 90%. Experience with vascular MR and enhanced CT influenced diagnostic accuracy. For the two vascular MR experts, average sensitivity and specificity of MR were 71% and 97%, and of CT 73% and 97%. In this pilot study, when CT and MR were interpreted with comparable expertise, they had similar accuracy for detecting pulmona

ISSN:1053-1807    

DOI:10.1002/jmri.1880060203

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe purpose of this article was to determine the frequency and imaging characteristics of nontumoral perfusion abnormalities observed on magnetic resonance imaging (MRI) obtained during arterial portography (MRAP). MRAP examinations done in 23 consecutive patients with malignant hepatic tumors were retrospectively and blindly reviewed by two readers for the presence of nontumoral perfusion abnormalities. MR images were assessed for the presence, location, shape, and type of nontumoral perfusion abnormalities, and correlated with intraoperative findings or follow‐up imaging studies. Fourteen nontumoral perfusion abnormalities were found in 10 patients (43%). Nontumoral perfusion abnormalities were categorized into these five types: triangular nontumoral perfusion defects not associated with a more proximal tumor (n = 6), triangular nontumoral perfusion abnormalities distal to a tumor (n = 2), hypoperfusion involving 1 or>1 segment (n = 2), hyperenhancement of the posterior part of the right hemiliver (n = 2), and gravity‐effect‐related perfusion abnormality (n = 2). Nontumoral perfusion abnormalities are seen frequently on MRAP examination. Recognition of these abnormalities remains crucial to avoid misdiag

ISSN:1053-1807    

DOI:10.1002/jmri.1880060204

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

年代:1996

数据来源: WILEY

摘要:

AbstractWe compared the liver enhancement of two super‐paramagnetic agents, polycrystalline iron oxide nano‐particles (PION) and PION coated with asialofetuin (ASF), in an experimental model of focal radiation‐induced hepatitis. PION, a reticuloendothelial system‐directed agent, and PION‐ASF, a hepatocellular‐directed agent, were compared for time‐dependent liver enhancement in an experimental model of radiation‐induced liver injury. Using the reticuloendothelial system (RES)‐directed PION, the normal, nonirradiated portion of the liver decreased in signal intensity (SI) with a mean negative enhancement of –66% ± 4, whereas the irradiated portion (60 Gy, 3 days before imaging) of the liver decreased in SI by –24% ± 2, significantly less (P<.05). SI changes in irradiated liver tissue using PION were dose‐dependent, being more pronounced with lower radiation exposure. The difference in SI changes induced by PION‐ASF between irradiated and nonirradiated liver was not statistically different, but SI decreased with a mean negative enhancement of –80% ± 2. The RES‐directed PION is more sensitive for the detection of radiation‐induced hepatitis than is the hepatocyte‐directed PION‐ASF. The insensitivity of PION‐ASF enhancement for diffuse liver injury may be clinically advantageous for detecting focal lesions i

ISSN:1053-1807    

DOI:10.1002/jmri.1880060205

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

年代:1996

数据来源: WILEY

摘要:

AbstractOur purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1‐weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1‐weighted images were studied with a 1.5‐T MR imager using pre‐ and serial postcontrast spoiled gradient‐echo (SGE) sequences (all patients), T2‐weighted fat‐suppressed spin‐echo sequences (all patients), precontrast T1‐weighted fat‐suppressed spin‐echo sequences (five studies in five patients), and precontrast out‐of‐phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1‐weighted, T2‐weighted, and fat‐attenuated T1‐weighted images; distribution of high SI in lesions on T1‐weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1‐weighted images and six patients had solitary tumors. Seventy‐two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1‐weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1‐weighted fat‐attenuated images, both on excitation spoiled fat‐suppressed spin‐echo or on out‐of‐phase SGE images with the exception of one fat‐containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out‐of‐phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat‐attenua

ISSN:1053-1807    

DOI:10.1002/jmri.1880060206

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

年代:1996

数据来源: WILEY

摘要:

AbstractWe investigated whether better visualization of the intrahepatic portal system could be obtained by adding magnetization transfer contrast (MTC) to three‐dimensional MR portography (3D‐MRP). In 15 healthy volunteers, 3D fast low‐angle shot images combined with an off‐resonance pulse were obtained after bolus injection of gadopentetate dimeglumine during one period of breath‐holding. Within 1 week after injection, MR images without MTC were obtained using the same scanning condition. MRPs with and without the MTC pulse were compared quantitatively and qualitatively. The contrast‐to‐noise ratio of the portal vein–liver was significantly higher in the group imaged with the addition of MTC. Qualitatively, the use of MTC improved peripheral portal branch depiction on maximum‐intensity projection images. Even when the MTC pulse was added to the conventional method of 3D data collection, it was possible to obtain images within one period of breath‐holding. In conclusion, the use of MTC can substantially enhance the

ISSN:1053-1807    

DOI:10.1002/jmri.1880060207

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

年代:1996

数据来源: WILEY

摘要:

AbstractOur objective was to evaluate the efficacy of MR imaging as compared with conventional hysterosalpingography (HSG) for the detection of fallopian tube patency after uterine injection of contrast material. Rabbit uterine horns (n= 18) were catheterized transvaginally. Five fallopian tubes were ligated and 11 were left unaltered. T1‐weighted gradient‐echo MR images were obtained before, during, and after injection of 1.0–3.0 mL of a dilute gadolinium‐containing contrast agent. Corresponding conventional studies were performed with an equivalent volume of iohexol. Images were evaluated by two blinded readers. Observers agreed in all cases on the presence (n= 11) or absence (n= 5) of peritoneal spill with conventional HSG. Interpretation of MR HSG concurred with conventional HSG in 14 of 16 cases for each observer (P>.05). Reasons for misdiagnosis included small amounts of spill (n= 2), artifact (n= 1), and subtle spill between bowel loops (n= 1). Sensitivity and specificity for MR HSG were 95.5% and 70%, respectively, for the diagnosis of tubal patency/occlusions. No statistical difference was found between MR HSG and conventional HSG for the diagnosis of fallopian tube patency/obstruction. Potential advantages of MR HSG include no ionizing radiation, potentially diminished local contrast toxicity, superior visualization of uterine fibroids and endometriosis, and visualization of ovaries. We conclude that this technique warrants further study, including the use of a primate model to better simulate human

ISSN:1053-1807    

DOI:10.1002/jmri.1880060208

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe aims of this preliminary study were to establish the efficacy and minimum effective dose of TG5(FdDO3A)52gadolinium dendrimer for contrast‐enhanced, three‐dimensional (3D) time of flight (TOF) magnetic resonance angiography (MRA) of the body. In a dose ranging study in eight rabbits (Group A), each of two animals received 0.03; 0.02; 0.01; or 0.005 mmol/kg of the agent for 3D‐TOF MRA of the pelvic circulation in the axial and coronal planes. An additional nine animals (Group B) received a dose of 0.02 mmol/kg for 3D‐TOF MRA of the mediastinum, abdomen or of the lower limbs. Quantitative and qualitative analyses of the images from Group A demonstrated a dose‐related reduction in saturation effects and improved visualization of vascular structures, with maximal augmentation of the contrast‐to‐noise ratio (CNR) at 0.03 mmol/kg. The dose of 0.02 mmol/kg was found to be the minimal effective dose at the three vas

ISSN:1053-1807    

DOI:10.1002/jmri.1880060209

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe purpose of this article is to review the basic principles and clinical applications of dynamic contrast‐enhanced MRI in the musculoskeletal system. This method of physiologic imaging provides clinically useful information by depicting tissue vascularization and perfusion, capillary permeability, and composition of the interstitial space. Different imaging, evaluation, and postprocessing techniques are described. The most important applications in the musculoskeletal system are identification of areas of viable tumor for biopsy, tissue characterization, and monitoring of preoperative chemotherapy. Practical guidelines for performing a dynamic contrast‐enhanced MR examination are propo

ISSN:1053-1807    

DOI:10.1002/jmri.1880060210

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

年代:1996

数据来源: WILEY

摘要:

AbstractUlnar collateral ligament (UCL) tears may be nondisplaced or displaced relative to the adductor pollicis aponeurosis. Nondisplaced tears typically heal with immobilization whereas displaced tears require surgery. Nineteen patients with UCL injuries were evaluated using MR imaging (MRI), MR arthrography, and stress radiography (SR) to determine the efficacy of these techniques in differentiating nondisplaced from displaced UCL tears. Nineteen patients with UCL injuries were evaluated. MRI was utilized in 5 patients, and MR arthrography in 14, with 12 of these 14 undergoing SR. They were followed until resolution of symptoms; those without relief, and those with suspected displaced UCL tears were surgically explored. Surgery and imaging was correlated. Eight patients underwent surgical repair. SR was abnormal in six patients treated surgically, but was negative in four of six conservatively treated patients with MR findings of nondisplaced tears. All patients with MR or MR arthrographic findings interpreted as being normal or as having a nondisplaced tear improved after conservative treatment. Based on surgical findings and clinical follow‐up, MR arthrography accurately diagnosed 13 of 14 UCL injuries, with one false‐positive interpretation. SR is often falsely negative. MR imaging with or without intra‐articular contrast injection proved to be accurate in a small series of patients with UCL inj

ISSN:1053-1807    

DOI:10.1002/jmri.1880060211

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

年代:1996

数据来源: WILEY