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排序方式: 共有686条查询结果,搜索用时 29 毫秒
41.
42.
目的:评价DSA下肢动脉跟踪造影图像拼接技术的应用价值。方法:对22例怀疑有下肢动脉病变的患者行下肢跟踪造影术,经工作站Paste软件后处理,拼接成下肢动脉全程图像,观察血管的显影情况。结果:本方法一次注射造影剂可显示一侧下肢动脉的全程图像。22例中均有不同程度的下肢血管狭窄、闭塞或假性动脉瘤等病变。结论:图像拼接技术能够更直接的显示下肢动脉病变,较传统DSA有明显的优势。 相似文献
43.
Cerebral blood flow (CBF) is commonly estimated from the maximum of the residue function deconvolved from bolus-tracking data. The bolus may become delayed and/or dispersed in the vessels feeding the tissue, resulting in the calculation of an effective residue function, Reff(t), whose shape reflects the distortion of the bolus as well as the hemodynamic tissue status. Consequently the CBF is often underestimated. Since regularizing the deconvolution introduces additional distortions to Reff(t), it is impossible to distinguish a true decrease in the CBF from bias introduced by abnormal vasculature. This may result in misidentification of tissue regions at risk of infarction, which could have serious clinical consequences. We propose a modified maximum-likelihood expectation-maximization (mML-EM) method, which is shown by way of simulations to improve the characterization of Reff(t) across a wide range of shapes. A pointwise termination approach for the iteration minimizes the effects of noise, and appropriate integral approximations minimize discretization errors. mML-EM was applied to data from a patient with left internal carotid artery (ICA) occlusion. The shape of each calculated Reff(t) was used to create a map indicating voxels affected by bolus delay and/or dispersion, where CBF estimates are inherently unreliable. Such maps would be a useful adjunct for interpreting bolus-tracking data. 相似文献
44.
J. G. Wagner K. D. Popat S. K. Das E. Sakmar H. Movahhed 《Journal of pharmacokinetics and pharmacodynamics》1981,9(2):147-166
Six normal male volunteers received 0.5 mg label doses of digoxin as (a) a bolus intravenous injection over 2 min, (b) a constant rate intravenous infusion over 1 hr, (c) a constant rate intravenous infusion over 3 hr, and (d) a solution in 5% dextrose given orally. Plasma concentrations of digoxin were measured by radioimmunoassay for a 4 day period and urinary excretion for a 6 day period after the single doses. The mean (coefficient of variation) total areas under the plasma concentration-time curves per 0.5 mg of digoxin were (a) 35.55 (14.8%), (b) 30.20 (27.7%), (c) 25.80 (35.5%), and (d) 15.47 (49.9%); the means differed significantly (0.01>p>0.005). The mean (coefficient of variation) total amounts excreted in the urine as a fraction of the dose were (a) 0.689 (6.31%), (b) 0.517 (20.4%), (c) 0.588 (16.8%), and (d) 0.374 (23.4%); the means differed significantly (p<0.001. Both the total clearance and the nonrenal clearance of digoxin differed significantly with the method of intravenous administration. The slower the rate of input of digoxin to the body, the greater were both the total clearance and the nonrenal clearance of the drug, which strongly suggests nonlinear pharmacokinetics.This work was supported in part by National Institutes of Health Grant 1 R01 HL 23862-01 and in part by National Institutes of Health General Clinical Research Center Grant 5M01 RR421. 相似文献
45.
Oesophageal meat bolus obstruction is often removed endoscopically/surgically with attendant morbidity and mortality. Anecdotal evidence suggests that fruit juices’ enzymes may dissolve meat boluses. To assess this, an in vitro study was carried out. Cooked chicken was tightly packed between 10 and 8 mL markers of 80, 10 mL syringes. Two millilitres of fresh juice from lemons, papaya, kiwi fruits, pineapples, frozen and then thawed pineapple juice, processed pineapple juice, Coca‐Cola® and saliva were added to 10 syringes each. By 4 h, the meat boluses significantly moved in the pineapple juice both fresh and frozen and kiwi juice groups (P < 0.001), little movement in the Coca‐Cola® group (P < 0.05), and no movement in the saliva, processed pineapple juice, lemon juice and papaya groups. In conclusion, pineapples and kiwi fruits contain enzymes which can dislodge meat boluses. Freezing does not denature the enzyme and provides a convenient way of storing the juice. 相似文献
46.
Dirksen MS Kaandorp TA Lamb HJ Doornbos J Corot C de Roos A 《Journal of magnetic resonance imaging : JMRI》2003,18(4):502-506
PURPOSE: To evaluate the effect of including the first-pass of a blood pool agent (BPA) on the image quality of three-dimensional navigator coronary MRA. MATERIALS AND METHODS: A pig model was used to perform: 1) T1 simulation of the BPA, based on actual blood samples, and 2) BPA-enhanced three-dimensional navigator coronary MRA, with or without inclusion of the first-pass of the BPA. The acquisitions with inclusion of the first-pass were timed with the use of a test bolus. The acquisitions without first-pass were started one minute after bolus injection (steady-state). A gradient echo acquisition technique with centric k-space sampling was applied. Comparison of both acquisitions was based on determination of contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and vessel length. RESULTS: T1 simulation shows a distinct T1 reduction during first-pass (to a level below 50 msec), increasing to 190 msec during steady-state. Images obtained with first-pass inclusion showed improved CNR (8.6 +/- 1.7 vs. 4.5 +/- 1.8), SNR (11.9 +/- 1.6 vs. 7.4 +/- 2.0), and vessel length (99.2 +/- 10.9 mm vs. 60.5 +/- 21.8 mm) as compared to the acquisitions during steady-state only (all: P< 0.05). CONCLUSION: The image quality of three-dimensional navigator coronary MRA combined with a gadolinium BPA in pigs is improved when starting the image acquisition during first-pass of the bolus. 相似文献
47.
Takahashi N Yoshioka H Yamaguchi M Saida Y Itai Y 《Journal of magnetic resonance imaging : JMRI》2003,18(1):80-89
PURPOSE: To assess the impact of the accelerated dynamic MR imaging (ADMRI) approach using parallel imaging for detecting hypervascular hepatocellular carcinomas (HCCs) and to evaluate the usefulness of a test bolus in examination and subtraction imaging in this setting. MATERIALS AND METHODS: Thirty patients with 135 HCCs underwent ADMRI using a two-dimensional gradient-recalled echo sequence with parallel imaging. Seventeen patients were evaluated without a test bolus and 13 patients with a test bolus. The detectability of HCCs was calculated between the groups with and without a test bolus. ADMRI was evaluated regarding the signal-to-noise ratio (SNR) of the lesion and the liver, the contrast-to-noise ratio (CNR) of the lesion vs. the liver, and the feasibility of subtraction images. RESULTS: ADMRI with and without a test bolus had almost equal sensitivity (92.5% and 92.6%). No significant difference was seen in the SNR of lesions and the CNR of lesions vs. livers between both groups. With a test bolus, ADMRI could depict the peak enhancement of nodules on the 2nd or 3rd dynamic phases and optimized the timing of peak lesion enhancement. Subtraction images could be obtained regarding minimal slice misregistration. CONCLUSION: ADMRI had high detectability of HCCs with and without a test bolus. 相似文献
48.
Daniel E. Goltz Billy T. Baumgartner Cary S. Politzer Marcus DiLallo Michael P. Bolognesi Thorsten M. Seyler 《The Journal of arthroplasty》2018,33(1):25-29
Background
Patient demand and increasing cost awareness have led to the creation of surgical risk calculators that attempt to predict the likelihood of adverse events and to facilitate risk mitigation. The American College of Surgeons National Surgical Quality Improvement Program Surgical Risk Calculator is an online tool available for a wide variety of surgical procedures, and has not yet been fully evaluated in total joint arthroplasty.Methods
A single-center, retrospective review was performed on 909 patients receiving a unilateral primary total knee (496) or hip (413) arthroplasty between January 2012 and December 2014. Patient characteristics were entered into the risk calculator, and predicted outcomes were compared with observed results. Discrimination was evaluated using the receiver-operator area under the curve (AUC) for 90-day readmission, return to operating room (OR), discharge to skilled nursing facility (SNF)/rehab, deep venous thrombosis (DVT), and periprosthetic joint infection (PJI).Results
The risk calculator demonstrated adequate performance in predicting discharge to SNF/rehab (AUC 0.72). Discrimination was relatively limited for DVT (AUC 0.70, P = .2), 90-day readmission (AUC 0.63), PJI (AUC 0.67), and return to OR (AUC 0.59). Risk score differences between those who did and did not experience discharge to SNF/rehab, 90-day readmission, and PJI reached significance (P < .01). Predicted length of stay performed adequately, only overestimating by 0.2 days on average (rho = 0.25, P < .001).Conclusion
The American College of Surgeons National Surgical Quality Improvement Program Surgical Risk Calculator has fair utility in predicting discharge to SNF/rehab, but limited usefulness for 90-day readmission, return to OR, DVT, and PJI. Although length of stay predictions are similar to actual outcomes, statistical correlation remains relatively weak. 相似文献49.
Background
The primary objective of this study was to determine rates of reoperation, ED visits, and hospital readmission after thyroid and parathyroid surgery at a tertiary hospital. A secondary objective was to determine if scores from the American College of Surgeons Surgical Risk Calculator (ACS SRC) predicted these events.Methods
We retrospectively reviewed the records of patients undergoing parathyroid and thyroid surgery between 2011 and 2014. Patients who underwent an unplanned reoperation, returned to the ED, or were readmitted to hospital were evaluated using the ACS SRC.Results
436 patients underwent thyroid and parathyroid operations. Rates of re-operations, ED visits and hospital readmissions after thyroid and parathyroid surgery were: 3.4%, 0.6% and 3.0% and 2.2%, 0% and 1.4%, respectively. 71% of patients who experienced post-operative complications scored below average on the ACS SRC, 17% scored above average and 12% scored average risk.Conclusions
The SRC did not predict re-operation, ED visits, or hospital readmission after thyroid or parathyroid operations. 相似文献50.
Silvia Martini Arianna Aceti Martina Furini Alessandra Munarini Cristina La Riccia Vilma Mantovani Giacomo Faldella Luigi Corvaglia 《JPEN. Journal of parenteral and enteral nutrition》2019,43(4):550-556
Background: Arachidonic acid (AA) and docosahexaenoic acid (DHA) are crucial for neural and visual development after premature birth. Preterm infants usually require tube feeding (TF) until the achievement of adequate oral feeding skills; the impact of TF on DHA and AA delivery has not been investigated yet. This study aimed to evaluate the effect of different TF techniques on the delivery of AA and DHA contained in human milk (HM). Methods: HM samples (65 mL each) were collected and divided into three 20‐mL aliquots. The remaining 5 mL served as baseline. Three TF techniques were simulated (1 for each aliquot): gravity bolus feeding (BF), 3‐hour continuous feeding using a horizontal feeding pump, and 3‐hour continuous feeding with the feeding pump angled at 45°. For horizontal continuous feeding (HCF) and 45° angled continuous feeding (ACF), aliquots delivered between 0 and 90 minutes (T1) and 91 and 180 minutes (T2) were collected separately. AA and DHA concentration was analyzed by gas chromatography/mass spectrometry and compared among the TF methods. DHA and AA delivery at T1 and T2 was also evaluated. Results: Fifty‐one simulated feeds were performed. DHA and AA amounts after BF and ACF did not differ significantly compared with baseline, whereas HCF resulted in significantly lower DHA and AA concentration. During T2, ACF delivered almost twice the DHA and AA amounts compared with T1. Conclusion: The delivery of HM AA and DHA is significantly affected by TF, with potential clinical implications. When BF is not tolerated, ACF might represent a feasible alternative to reduce TF‐related DHA and AA loss. 相似文献