首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
OBJECTIVE: The tissue rim sign-a rim or halo of soft-tissue attenuation seen around the circumference of an intraureteral calculus on unenhanced axial CT-has been described as useful in differentiating ureteral calculi from extraurinary abdominal or pelvic calcifications. The purpose of this study was to determine the prevalence of the tissue rim sign in patients with ureterolithiasis and extraurinary calcifications and to determine the relationship between the tissue rim sign, the size of a calculus, and the degree of urinary obstruction. MATERIALS AND METHODS: Unenhanced helical CT studies followed by excretory urography were obtained in 59 patients with suspected acute ureterolithiasis. Each calcification along the expected course of the ureter seen on axial CT scans was categorized as a ureteral calculus or as an extraurinary calcification. Each categorization was based on CT, urographic, and clinical findings and the presence or absence of a tissue rim sign. When the outer wall of the ureter could not be seen because there was no clear fat plane at the level of the calcification on CT, the sign was categorized as "indeterminate." The size of the calculus was measured on CT, and the degree of urinary obstruction was estimated on the basis of the urograms. RESULTS: Thirty-two patients each had a single ureteral calculus. Of these patients, CT revealed a positive tissue rim sign in 16 patients (50%), was negative in five patients (16%), and was indeterminate in 11 patients (34%). In addition, we saw 57 extraurinary calcifications in 18 patients (11 patients with ureteral calculi and seven patients without ureteral calculi). None of the 57 extraurinary calcifications was associated with a positive tissue rim sign. The tissue rim sign was negative in 39 (68%) of the 57 extraurinary calcifications and indeterminate in the remaining 18 (32%). Ureteral calculi with a negative tissue rim sign were larger than ureteral calculi with a positive tissue rim sign (p < .01). A high degree of obstruction was present in four of five patients with ureteral calculi for which CT showed a negative tissue rim sign. Conversely, six of 16 patients in whom CT revealed a positive tissue rim sign also had a high degree of obstruction. Therefore, no clear relationship was found between the degree of obstruction and the presence of a positive tissue rim sign. CONCLUSION: A positive tissue rim sign is specific for the diagnosis of ureterolithiasis. However, a negative tissue rim sign does not preclude such a diagnosis. The presence or absence of this tissue rim sign correlates with the size of a calculus but not with the degree of urinary obstruction. When CT reveals an indeterminate tissue rim sign, careful inspection for other CT findings, such as ipsilateral ureteral dilatation, perinephric edema, dilatation of the intrarenal collecting system, and renal swelling, is necessary.  相似文献   

2.
PURPOSE: To identify imaging features at unenhanced helical computed tomography (CT) that help differentiate distal ureteral calculi from pelvic phleboliths. MATERIALS AND METHODS: Retrospective analysis was performed of 184 pelvic calcifications identified at unenhanced helical CT in 113 patients. The size, shape, and attenuation of each calcification were recorded in addition to the presence of a central lucency and the appearance of the adjacent soft tissues. With profile analysis, a graphic representation was generated of attenuation in each pixel along a line drawn through each calcification. RESULTS: Geometric configuration was seen in eight (21%) calculi but not in any phleboliths. Differences were significant (P < .0001) between the mean attenuation of calculi and that of phleboliths. Among phleboliths, none had a mean attenuation greater than 278 HU, 13 (9%) had a visible central lucency, 31 (21%) had a bifid peak at profile analysis, 30 (21%) had the "comet sign" (adjacent eccentric, tapering soft-tissue mass corresponding to the noncalcified portion of a pelvic vein), and three (2%) had the soft-tissue rim sign (edema of the ureteral wall). Among calculi, none had a central lucency, bifid peak, or comet sign, but 29 (76%) had the soft-tissue rim sign. CONCLUSION: Analysis of pelvic calcifications at unenhanced helical CT can help differentiate calculi from phleboliths.  相似文献   

3.
INTRODUCTION: High-resolution computed tomography (HRCT) with iodinated contrast material has been used by many authors to study solitary pulmonary nodules (SPNs). The degree of enhancement was correlated with the nodule malignancy. MATERIAL AND METHODS: Forty adult patients were examined, before and after contrast agent administration, with incremental dynamic CT. We selected 22 patients with SPNs (3-30 mm phi, except one with 40 mm phi). The CT numbers of the inner nodule were calculated before and 1, 2 and 3 minutes after the i.v. administration of a weight-related dose (1.5 mL/kg/min) of nonionic iodinated contrast agent. A dose of 100 mL contrast agent was used in the first 6 patients. The difference in CT numbers between unenhanced images and the images with maximum enhancement (max. attenuation) was also calculated. RESULTS: Histologic diagnoses included 4 tuberculomas, 3 hamartomas and 15 malignant tumors (9 adenocarcinomas, 5 squamous cell carcinomas and 1 non-Hodgkin lymphoma). The CT numbers (in Hounsfield units, HU) of malignant nodules ranged 12-31 HU (mean: 21.5 HU) before contrast agent administration; the "long-standing" tuberculomas ranged 11-22 HU (mean: 16.5 HU) and the hamartomas had a mean density of 10.5 HU. We excluded for the study two "fresh" tuberculomas, one of which was surrounded by a low-attenuation infiltrate (the halo sign). We selected a threshold value of 20 HU on enhanced CT images to distinguish malignant (> or = 20 HU) from benign (< or = 20 HU) nodules. All lung cancers had complete enhancement (mean density: 35.5 HU). With 20 HU as the threshold value for a positive test, sensitivity was 100%, specificity 85.7%, positive predictive value 93.8% and negative predictive value 100%; test bias was 1.067. CONCLUSION: Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-D glucose is reported to be as accurate as enhanced HRCT, but it does not provide accurate morphological information, is not widely available and it is quite expensive: therefore, in our opinion, CT should be preferred. After examining over 100 patients, we may use our results in the decision analysis comparing surgical risk with cancer risk.  相似文献   

4.
Objective: The aim of the study was to analyze the CT morphology features of pulmonary sclerosing hemangiomas (PSHs) and improve the diagnosis ability of this disease. Methods: The 18 cases of pulmonary sclerosing hemangioma (PSH) confirmed by operation and histopathology from August 2002 to May 2009 were collected, including 17 females and 2 males, aged from 19 to 60 years old, with an average age of 43 years. All the cases underwent plain CT scan, among them,16 cases received enhanced CT scan. Results: The 18 cases had isolated mass. Mean long-axis diameter of these lesions was (2.7 ± 1.3) cm (range, 1.9-4.2 cm). Of all cases, 5 cases (27.8%) were round in shape, 9 cases (50%) were oval, 4 cases (22.2%) were lobulated, and 14 cases (77.8%) were smooth margin. The air meniscus sign was in 2 cases (11.1%), and the halo sign in 3 cases (16.7%). Two cases (11.1%) contained small nodular calcification, the remaining 16 cases (70%) were homogeneous density, the CT density of the masses ranged from 24-47 HU, and the mean value was 35 HU. Sixteen cases received enhanced scan, the welt vessel sign was in 8 cases (44.4%),1 case showed less enhancement, 5 cases showed marked homogeneous enhancement and 10 cases showed intense and patchy heterogeneous enhanced. The CT density of the enhancing masses ranged from 60-110 HU, the mean value was 35 HU, and the net enhancement value was 14-80 HU, the mean value was 55 HU. Conclusion: PSH should be considered in middle-aged female whose CT found that single round or oval pulmonary nodules, with smooth margin, or associated with the air meniscus sign, the halo sign, or the marked enhancement.  相似文献   

5.
The clinical data and radiographs of 50 neonates with pneumopericardium (PPC) were reviewed. Most of these neonates were premature, low-birth-weight infants with hyaline membrane disease who required ventilatory assistance. The presence of other extraventilatory air prior to (or concurrent with) PPC, the use of cardiopulmonary resuscitation with intracardiac drug administration, and improper endotracheal tube placement were contributory factors. However, it was not possible to determine why some infants progressed to PPC and others, with similar disease and predisposing conditions, did not. The primary radiographic sign of PPC is the "halo" sign, which was apparent in 96% of these cases. When this sign was not present, other signs, such as the "pericardial line" sign, were helpful. The overall mortality was 72%. Thirty-three per cent of the fatalities were related to PPC; however, the long-term prognosis is probably more closely related to the severity of underlying lung disease or other complications than to PPC.  相似文献   

6.
OBJECTIVE: This study assesses intravascular density produced by ionic and nonionic contrast material and its effect on visualization of stenoses by CT angiography. MATERIALS AND METHODS: CT angiography was performed using a 32-vessel phantom to study grades of luminal stenoses (0-100%), three lengths of stenoses (1, 3, and 5 mm), and two angles of inclination into the stenoses (45 degrees and 75 degrees). Scans were obtained with a slice thickness of 2 mm, a slice interval of 1.5 mm, a pitch of 1.0, a voltage of 120 kV, and a current of both 100 and 200 mA. Vessels were oriented parallel to the z-axis, and opacified with ionic and nonionic contrast material that had densities of 100, 150, 200, 250, 300, and 350 H. Cross-sectional luminal diameters were measured in and out of the stenoses. Edge definition and halo artifact for each vessel were graded by an investigator who was unaware of the contrast material density used. RESULTS: A contrast density of 150 H as revealed by CT angiography yielded the most accurate stenosis measurements with ionic contrast material. For nonionic contrast material, attenuation values of 150 and 200 H produced the best results on CT angiography. A density of 100 H or greater than 250 H significantly increased the error of vessel measurement (p = .001) for both types of contrast material. For the two current levels tested (100 and 200 mA), no statistical difference was found. CONCLUSION: The accuracy of CT angiography in measuring carotid stenosis depends on the luminal attenuation value. An optimum contrast density is 150 H for ionic contrast material; for nonionic contrast material, 150-200 H (at the window and level settings of 300 H and 40 H).  相似文献   

7.
BACKGROUND: In patients with unstable cervical spine injuries initially managed with in-line traction, there is some risk of loss of cervical alignment and of new neurologic deficit when the halo vest is applied. This report outlines a simple technique which facilitates halo application in these patients. METHODS: The back of the halo vest is "prepositioned" before traction is instituted. Once alignment is optimized, halo vest application is easily completed without lifting the patient or discontinuing cervical traction. RESULTS: The authors have used this technique in four patients without complication. CONCLUSIONS: In patients with unstable cervical spine injuries who require an initial period of in-line traction, halo vest application is made easier and safer by "prepositioning" the back of the vest.  相似文献   

8.
在研究胶东典型石英脉型、蚀变岩型金矿床深部盲矿预测构造叠加晕模型的基础上,总结其共性,建立了胶东石英脉型和蚀变岩型构造叠加晕理想模式,确定了盲矿预测的5条构造叠加晕准则。在研究预测中,先后对多个金矿进行跟踪研究,根据预测靶位见矿情况,总结不见矿靶位原因,修改完善预测模式和盲矿预测标志,并向矿床深部不断推进预测。构造叠加晕找盲矿法在理论和方法技术研究方面都取得了新的突破性进展,不仅完善和丰富了构造叠加晕找盲矿理论,方法技术不断完善和趋于成熟。应用各矿床构造叠加晕模式和盲矿预测标志对矿区深部进行预测,取得了显著的找矿效果。  相似文献   

9.
BACKGROUND: When an asymptomatic adrenal mass is incidentally discovered on abdominal CT scans, the distinction between a nonhyperfunctioning adenoma and a nonadenoma would be important. METHODS: We evaluated the CT findings of 36 adrenal masses (14 nonhyperfunctioning adenomas, 22 nonadenomas) in 34 patients with no evidence of hormonal hypersecretion. CT attenuation values of adrenal masses on CT scans were calculated by setting a circular region of interest as large as possible in the center of each adrenal mass. RESULTS: Below 20 HU in CT attenuation values, all adrenal masses, except one case of ganglioneuroma with myxomatous change, were nonhyperfunctioning adenomas. With an arbitrary threshold of 20 HU, the sensitivity of CT attenuation values in distinguishing nonhyperfunctioning adenomas from nonadenomas was 64%, the specificity was 95%, and the accuracy was 83%. When decreasing the threshold to 15 HU, the sensitivity was 64%, the specificity was 100%, and the accuracy was 86%. The CT attenuation value on noncontrast CT was more useful for making this distinction than the size and interior homogeneity. CONCLUSIONS: Our data suggest that an asymptomatic adrenal mass with homogeneous low attenuation (< or = 15 HU) and less than or equal to 4 cm indicates a nonhyperfunctioning adenoma, and no further examinations are necessary. CT attenuation value on non-contrast CT is the most important discriminatory factor.  相似文献   

10.
PURPOSE: To assess the attenuation of the adrenal gland with computed tomography (CT) before and after multiple phases of contrast enhancement in both control subjects and patients with adenomas and nonadenomas. MATERIALS AND METHODS: Seventy-two patients with 78 adrenal masses (41 adenomas, 37 nonadenomas) underwent helical CT. Forty subjects served as controls. Unenhanced CT was performed followed by enhanced CT at 30, 60, 90, and 180 seconds and 30 minutes. RESULTS: At unenhanced CT, mean attenuation was 4 HU +/- 16 for adenomas compared with 37 HU +/- 12 for the nonadenomas (P < .001) and 24 HU +/- 3 for normal glands. Although the mean attenuation of nonademonas was significantly greater than that of adenomas on 60- and 90-second scans (P < .001), there was greater overlap in attenuation of the adenomas and nonadenomas than on unenhanced images. At 180 seconds, nonadenomas had higher attenuation than adenomas (73 HU +/- 17 vs 41 HU +/- 18; P < .001). At 30 minutes, all adenomas had attenuation less than 37 HU, whereas all nonadenomas had attenuation greater than 41 HU. CONCLUSION: Delayed-enhanced CT scans obtained 30 minutes after administration of contrast material can enable differentiation of adenomas and nonadenomas.  相似文献   

11.
When trying to establish the likely anatomical site (preganglionic or postganglionic) of a lesion causing congenital Horner's syndrome, the distribution of facial flushing (the "harlequin" sign), may be seen. In babies and young children, facial flushing is a relatively simple clinical sign to demonstrate, compared with facial sweating. In unilateral facial flushing the areas that do not flush are almost always identical to the anhidrotic areas. However, neither facial flushing nor testing the pupil reactions with pholedrine or hydroxyamphetamine can be relied on to predict the probable site of any lesion causing congenital Horner's syndrome. Two patients with congenital Horner's syndrome are presented which demonstrated the "harlequin" sign and in whom clinical examination and pharmacological testing gave conflicting evidence for localisation of the site of the causative lesion. The presentation of congenital Horner's syndrome should be investigated and include MRI or CT to exclude a serious underlying cause.  相似文献   

12.
OBJECTIVE: Our goal was to describe attenuation differences bordered by a straight line in the right hepatic lobe on enhanced CT in patients with right adrenal tumors and to discuss the cause of this appearance. MATERIALS AND METHODS: Three patients showing attenuation differences bordered by a straight line were discovered in the CT files of 26 cases of right adrenal tumor over 3 cm in diameter. All CT scans were examined by incremental dynamic study. RESULTS: Two patients had large zone of hyperattenuation in the right lobe bordered with a straight line intersecting both anterior branches of the right portal vein and the inferior vena cava (IVC). A third patient and one of the two patients mentioned already had zones of relative hyper- and hypoattenuation in the medial portion of the posterior hepatic segment, respectively. All three patients had large right adrenal tumors, which severely compressed the right hepatic vein near its confluence with the IVC and/or the IVC in or below its intrahepatic portion. The distribution of attenuation differences was similar to the hyperattenuation at CT arteriography or perfusion defect at CT arterial portography under temporary balloon occlusion of the right hepatic vein and inferior right hepatic vein, respectively. CONCLUSION: Straight-bordered attenuation differences within the right hepatic lobe at dynamic CT can be caused by compression of the right hepatic vein by large right adrenal tumors.  相似文献   

13.
The halo external orthosis has been used extensively for cervical immobilization after spine surgery or trauma, usually without serious complications. However, nine brain abscesses have been reported as complications following the use of halo orthosis. We report on a 53-year-old man who underwent anterior cervical fusion for cervical myelopathy, followed by the application of a halo orthosis. Approximately 4 weeks postfusion, loosening of the right anterior pin was recognized and the pin was tightened, as the pin-site was clean. One week later, purulent material was discharged from the pin hole when the pin was removed after it had loosened again. Enhanced computed tomography (CT) demonstrated an abscess on the right side of the brain. After the administration of antibiotics, the abscess resolved without surgical intervention. We describe asymptomatic brain abscess complicating the use of a halo orthosis and review the clinical features, symptoms, and outcomes; we also discuss the mechanism that induced brain abscess. Most reported cases of abscess have been associated with pin-site infection or tightening after late pin loosening. The present case indicates the importance of early recognition of symptoms and signs associated with brain abscess in patients with a halo orthosis.  相似文献   

14.
PURPOSE: Two percent glutaraldehyde on colonic mucosa may result in a toxic colitis, and the clinical features may mimic those of colonic ischemia. The study was performed to determine the radiologic appearance of glutaraldehyde-induced toxic colitis. MATERIALS AND METHODS: A retrospective review was performed with the clinical and imaging findings in four patients with glutaraldehyde-induced colitis seen during a 6-year period. RESULTS: Patients developed a self-limited syndrome of cramps and abdominal pain, tenesmus, and rectal bleeding within 48 hours of uncomplicated sigmoidoscopy or colonoscopy. Sample cultures excluded enteric pathogens. Computed tomography (CT) demonstrated circumferential thickening of the colonic wall in a left-sided distribution in all patients. Heterogeneous mural enhancement (target-sign appearance) was noted in two patients. Follow-up CT studies confirmed resolution of mural wall thickening with conservative management. CONCLUSION: The clinical and radiologic features of glutaraldehyde-induced toxic colitis may mimic those of colonic ischemia. This complication should be suspected in patients who develop hemorrhagic colitis immediately after undergoing colonoscopy.  相似文献   

15.
Pseudomembranous colitis (PMC) is an infectious colitis usually occurring as a complication of antibiotic therapy. The computed tomography (CT) findings of 10 patients with PMC are reviewed. All patients demonstrated an abnormal large bowel wall with an average thickness of 13 mm (range 7-31 mm). Additional, but less frequent findings included mesenteric inflammation, ascites, pleural effusions, and dilatation of the large or small bowel. Pancolonic involvement was seen in 7 cases, while three patients had focal colitis. Although the CT appearance of PMC is not specific, the diagnosis may be suggested in the proper clinical setting.  相似文献   

16.
Alveolar extension of pulmonary adenocarcinoma is characteristically demonstrated as an area of ground-glass attenuation (GGA). We correlated the CT attenuation value of GGA with the aeration rate of the pathologic specimen measured with a high-resolution image analyzer (OLYMPUS). The CT values of GGA seen in fourteen adeno-carcinomas were measured for helical (slice thickness 10mm) and thin slice CT (slice thickness 1 or 2mm). A positive correlation was found between the CT attenuation value and the aeration rate in the pathologic specimen (Spearman analysis < 1%).  相似文献   

17.
A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named "sheet line source" was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99mTc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99mTc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations.  相似文献   

18.
OBJECTIVE: This report describes the unusual presentation of Clostridium difficile colitis in five patients with cystic fibrosis and the role of CT in first suggesting the correct diagnosis in this group of patients. Because of the absence of watery diarrhea and the presence of abdominal bloating and decreased stooling, cystic fibrosis patients with C. difficile colitis will be treated for stool impaction, meconium ileus equivalent, or distal intestinal obstruction syndrome. CT of the abdomen, performed in these five patients because of their lack of improvement after standard therapy for stool impaction, showed an extensive pancolitis later confirmed to be caused by C. difficile infection. CONCLUSION: In patients with cystic fibrosis, imaging findings of a pancolitis should raise the possibility of C. difficile colitis despite the lack of watery diarrhea. Anticlostridial treatment can be initiated before bacteriologic confirmation is obtained.  相似文献   

19.
Objective: The aim of our study was to demonstrate the CT features of solid pseudopapillary tumor of the pancreas (SPTP) so as to improve the imaging diagnostic abilities. Methods: The CT materials of 10 cases with surgery andpathology proved SPTP were retrospectively analyzed, including 8 females and 2 males, their age ranged from 12 to 54years (average being 27.2 years). All of the 10 cases underwent spiral CT scan and also with contrast enhancement before surgery. Results: All of the 10 cases were isolated mass. They were located at the head (n = 5), tail (n = 4), and body (n =1) of the pancreas. Their shapes were round (n = 3), oval (n = 4), and irregular (n = 3). The long-axis diameter ranged from 2.1-8.6 cm (mean 6.5 cm). All of neoplasms consisted of solid and cystic components. Mostly solid components in 5 cases,nearly the same proportion of solid and cystic part in 3 cases, and mostly cystic components in 2 cases. After dynamic contrast-enhanced, the solid parts of the lesion showed progressive enhancement and the cystic parts of the lesion showed no enhancement. Calcification was noted in 5 cases, such as the spot, line-like, small nodules or patchy calcification. Fluiddebris level and "floating cloud" sign were noted in one case. In one case of mostly cystic components, patchy area of high attenuation were shown on CT imaging which then was proved as old hemorrhage by pathologic evaluation. Seven cases were completely encapsulated and made more remarkable on post-contrast images. Three cases had incomplete capsules,and adhesion to the surrounding tissues could be seen during operation, including one case in which invasion to the adjacent adipose tissues near the inferior vena cava and walls of the duodenum could be seen under the microscope. Pancreatic duct broadening or hepatic duct dilatation was caused by tumor each in 1 case. All of the 10 cases had no enlargement of the intra-abdominal lymph nodes or distant organ metastasis. Conclusion: SPTP occurs mainly in young women and has comparatively characteristic CT imaging features: a large solid and cystic tumor of pancreas, sharp edges, the solid parts of the lesion showed progressive enhancement, a few with hemorrhage and calcification.  相似文献   

20.
A case of deep-seated brain abscess that ruptured twice into the ventricle and resulted in death is presented. A 45-year-old man had experienced pyrexia and headache for 3 days before admission. On admission he was somnolent (GCS: 13) but there were no abnormal neurological findings except nuchal rigidity and Kernig's sign. Computed tomography (CT) scan showed a ring enhanced mass near the left caudate head and dilated ventricles. In comparison with CT performed at the former hospital it was diagnosed that a rupture into the ventricle of the brain abscess had occurred. Ventricular drainage was performed at once and white purulent cerebrospinal fluid was obtained. Thereafter, he was treated with some antibiotics and his conditions seemed to stabilize for a while. Serial CT images demonstrated that the size of the abscess seemed to be enlarging. Just when we planned to undertake stereotactic aspiration, the second ventricular rupture occurred and he died. According to this case, it is suggested that once a deep-seated brain abscess near the ventricular system is suspected, it should be aspirated by means of CT-guided stereotactic surgery immediately.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号