Dotlike hemosiderin spots on T2*-weighted magnetic resonance imaging as a predictor of stroke recurrence: a prospective study

2004 ◽  
Vol 101 (6) ◽  
pp. 915-920 ◽  
Author(s):  
Toshio Imaizumi ◽  
Yoshifumi Horita ◽  
Yuji Hashimoto ◽  
Jun Niwa
Keyword(s):  
Magnetic Resonance ◽  
Small Vessel Disease ◽  
Small Sample Size ◽  
Pearson Correlation ◽  
Small Sample ◽  
Stroke Recurrence ◽  
Amyloid Angiopathy ◽  
Content Type ◽  
A Prospective Study ◽  
Fine Print

Object. Microangiopathy associated with hypertension is a notable cause of cerebral small vessel disease (SVD), including deep intracerebral hemorrhage (ICH) and lacunar infarct. Dotlike low-intensity spots (dotlike hemosiderin spots: dotHSs) on T2*-weighted magnetic resonance (MR) images have been histologically diagnosed as old cerebral microbleeds associated with lipohyalinosis, amyloid angiopathy, or other microangiopathies and located in deep or subcortical regions. The aim of this study was to determine whether dotHSs indicate the severity of microangiopathy, and if so, whether large numbers of deep dotHSs are associated with SVD recurrence. Methods. The authors prospectively analyzed the number of dotHSs in 337 patients—191 men and 146 women with a mean age of 66 ± 10.4 years (range 37–94 years)—with SVD (199 ICHs and 138 lacunar infarcts) who had been consecutively admitted to Hakodate Municipal Hospital. The follow-up period was 3.5 to 42 months (22.5 ± 13.1 months). Patients were divided into two groups based on the recurrence. The hazard ratio (HR) for recurrence was estimated based on the Cox proportional hazard model by using the number of deep and subcortical dotHSs as well as other factors. Of 337 patients, 20 were readmitted with recurrence. Results of a multivariate analysis revealed an elevated rate of recurrence in patients with many subcortical dotHSs (≥ 5, HR 4.36, p = 0.0019) or a history of ICH (HR 3.82, p = 0.014). A trend toward a positive correlation (Pearson correlation coefficient 0.548, p < 0.0001) was found between the number of deep and subcortical dotHSs. Conclusions. Although a small sample size limited the power of analyses, the findings indicate that a large number of subcortical dotHSs may predict SVD recurrence.

scholarly journals Efficacy of T2 Magnetic Resonance Assay in Monitoring Candidemia after Initiation of Antifungal Therapy: the Serial Therapeutic and Antifungal Monitoring Protocol (STAMP) Trial

2018 ◽  
Vol 56 (4) ◽  
Author(s):  
Eleftherios Mylonakis ◽  
Ioannis M. Zacharioudakis ◽  
Cornelius J. Clancy ◽  
M. Hong Nguyen ◽  
Peter G. Pappas
Keyword(s):  
Magnetic Resonance ◽  
Blood Culture ◽  
Antifungal Therapy ◽  
Small Sample Size ◽  
Small Sample ◽  
Blood Cultures ◽  
Source Control ◽  
Rank Test ◽  
Duration Of Treatment ◽  
Content Type

ABSTRACTThe performance of blood culture for monitoring candidemia clearance is hampered by its low sensitivity, especially during antifungal therapy. The T2 magnetic resonance (T2MR) assay combines magnetic resonance with nanotechnology to identify wholeCandidaspecies cells. A multicenter clinical trial studied the performance of T2MR in monitoring candidemia clearance compared to blood culture. Adults with a blood culture positive for yeast were enrolled and had blood cultures and T2MR testing performed on prespecified days. Thirty-one patients completed the trial. Thirteen of the 31 patients (41.9%) had at least one positive surveillance T2MR and/or blood culture result. All positive blood cultures (7/7 [100%]) had an accompanying positive T2MR result with concordance in the identifiedCandidasp., while only 7/23 (30.4%) T2MR results had an accompanying positive blood culture. There was one case of discordance in species identification between T2MR and the preenrollment blood culture with evidence to support deep-seated infection by theCandidaspp. detected by the T2MR assay. Based on the log rank test, there was a statistically significant improvement in posttreatment surveillance using the T2MR assay compared to blood culture (P= 0.004). Limitations of the study include the small sample size and lack of outcome data. In conclusion, the T2MR assay significantly outperformed blood cultures for monitoring the clearance of candidemia in patients receiving antifungal therapy and may be useful in determining adequate source control, timing for deescalation, and optimal duration of treatment. However, further studies are needed to determine the viability ofCandidaspecies cells detected by the T2MR assay and correlate the results with patient outcomes. (This study is registered at ClinicalTrials.gov under registration number NCT02163889.)

Ultrasonographic screening in infants with isolated spinal strawberry nevi

2003 ◽  
Vol 98 (3) ◽  
pp. 247-250 ◽  
Author(s):  
Rebecca M. Allen ◽  
Michael A. Sandquist ◽  
Joseph H. Piatt ◽  
Nathan R. W. Selden
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Spinal Dysraphism ◽  
Occult Spinal Dysraphism ◽  
Imaging Evaluation ◽  
Content Type ◽  
Surgical Exploration ◽  
Clinical Literature ◽  
A Prospective Study ◽  
Fine Print

Object. The authors performed spinal ultrasonography and/or magnetic resonance (MR) imaging in 20 consecutive newborns with spinal strawberry nevi. Methods. In 15 patients the strawberry nevi were isolated and in five they were associated with other cutaneous markers of occult spinal dysraphism (OSD). In four of five patients with additional cutaneous markers, but in none of those without, MR imaging and surgical exploration demonstrated OSD. The authors found that strawberry nevi in isolation do not appear to indicate underlying dysraphic states. The sparse clinical literature on this topic, which is reviewed, confirms an association between OSD and strawberry nevi presenting in conjunction with other cutaneous signatures. By contrast, spinal strawberry nevi occurring alone may not indicate the presence of underlying dysraphism. Conclusions. A prospective study of larger numbers of patients with isolated strawberry nevi, undergoing MR imaging evaluation, is necessary to determine whether neuroimaging screening in these patients is indicated.

Use of intraoperative ultrasound for localizing tumors and determining the extent of resection: a comparative study with magnetic resonance imaging

1996 ◽  
Vol 84 (5) ◽  
pp. 737-741 ◽  
Author(s):  
Maarouf A. Hammoud ◽  
B. Lee Ligon ◽  
Rabih Elsouki ◽  
Wei Ming Shi ◽  
Donald F. Schomer ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Radiation Effects ◽  
Intraoperative Ultrasound ◽  
Extent Of Resection ◽  
Brain Lesions ◽  
Content Type ◽  
Recurrent Tumors ◽  
A Prospective Study ◽  
Fine Print

✓ A prospective study of 70 patients with intraparenchymal brain lesions (36 gliomas and 34 metastases) was performed to evaluate the efficacy of intraoperative ultrasound (IOUS) in localizing and defining the borders of tumors and in assessing the extent of their resection. Eighteen of the 36 glioma patients had no previous therapy. All of these 18 tumors were well localized by IOUS; margins were well defined in 15 and moderately defined in three. The extent of resection was well defined on IOUS in all 18 patients, as confirmed by measurements taken on postoperative magnetic resonance (MR) images (p = 0.90). The remaining 18 patients with gliomas had undergone previous surgery and/or radiation therapy; five had recurrent tumors and 13 had radiation-induced changes. The extent of resection of the recurrent tumors was well defined in all but one patient, as confirmed by postoperative MR imaging. The extent of resection was poorly defined in all 13 patients whose pathology showed radiation effects. All 34 metastatic lesions were well localized and had well-defined margins. In addition, IOUS accurately determined the extent of resection in all cases; the results were confirmed with postoperative MR imaging. In conclusion, IOUS is not only helpful in localizing and defining the margins of gliomas and metastatic brain lesions, it also accurately determines the extent of resection, as confirmed by postoperative MR imaging. This assessment does not apply, however, when the lesion is due primarily to radiation effect.

Hearing preservation in patients undergoing vestibular schwannoma surgery: comparison of middle fossa and retrosigmoid approaches

1998 ◽  
Vol 88 (5) ◽  
pp. 840-845 ◽  
Author(s):  
Richard M. Irving ◽  
Robert K. Jackler ◽  
Lawrence H. Pitts
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannoma ◽  
Small Sample Size ◽  
Hearing Preservation ◽  
Early Postoperative Period ◽  
Small Sample ◽  
T Test ◽  
Middle Fossa ◽  
Content Type ◽  
Fine Print

Object. The goal of this retrospective study was to evaluate hearing preservation after surgery for vestibular schwannoma in which the middle fossa (MF) or retrosigmoid (RS) approaches were used. Hearing preservation in vestibular schwannoma surgery can be achieved by using either the MR or RS approach. Comparative outcome data between these approaches are lacking, and, as a result, selection has generally been determined by the surgeon's preference. Methods. The authors have compared removal of small vestibular schwannomas via MF and RS approaches with regard to hearing preservation and facial nerve function. The study group was composed of consecutively treated patients with vestibular schwannoma, 48 of whom underwent operation via an MF approach and 50 of whom underwent the same number of RS operations. Tumors were divided into size-matched groups. Hearing results were recorded according to the American Academy of Otolaryngology—Head and Neck Surgery criteria, and facial nerve outcome was recorded as the House—Brackmann grade. Overall, 26 (52%) of the patients treated via the MF approach achieved a Class B or better hearing result compared with seven (14%) of the RS group. Some hearing was preserved in 32 (64%) of the patients in the MF group and in 17 (34%) of the RS group. The results obtained by using the MF approach were superior for intracanalicular tumors (p = 0.009, t-test), and for tumors with a cerebellopontine angle (CPA) component measuring 0.1 to 1 cm (p = 0.006, t-test). For tumors in the CPA that were 1.1 to 2 cm in size, our data were inconclusive because of the small sample size. Facial weakness was seen more frequently after MF surgery in the early postoperative period, but results were equal at 1 year. Conclusions. The results of this study have demonstrated a more favorable hearing outcome for patients with intracanalicular tumors and tumors extending up to 1 cm into the CPA that were removed via the MF when compared with the RS approach.

A new magnetic resonance head coil and head immobilization device for gamma knife radiosurgery: an analysis of geometric distortion and signal/noise characteristics

2002 ◽  
Vol 97 ◽  
pp. 563-568 ◽  
Author(s):  
Paul Jursinic ◽  
Robert Prost ◽  
Christopher Schultz
Keyword(s):  
Magnetic Resonance ◽  
Gamma Knife Radiosurgery ◽  
Geometric Distortion ◽  
Gradient Field ◽  
Main Magnetic Field ◽  
Content Type ◽  
Signal Noise ◽  
Noise Characteristics ◽  
Head Coil ◽  
Fine Print

Object. The authors report on a new head coil into which the Leksell aluminum localization frame can be easily and securely mounted. Mechanically, the head coil interferes little with the patient. Methods. The head coil, which is for magnetic resonance (MR) imaging, is a 12-element quadrature transmitand-receive high-pass birdcage coil with a nominal operation frequency (63.86 MHz). The coil was built into a plastic housing. This new head coil minimizes patient motion and provides a 20% increase in signal/noise ratios compared with standard head coils. An MR image test phantom was mounted in the coil and this allowed quantification of image distortion due to inhomogeneities in the main magnetic field, nonlinearity in the gradient field, and paramagnetism of the aluminum headframe. There were no significant differences in geometric distortion between the new head coil and the standard coil. Conclusions. The new head coil has advantages for reducing patient movement artifacts and has a better signal/noise ratio with no reduction in geometric accuracy.

Improving new product development performance by risk management

2016 ◽  
Vol 31 (3) ◽  
pp. 418-425 ◽  
Author(s):  
Mehran Salavati ◽  
Milad Tuyserkani ◽  
Seyyede Anahita Mousavi ◽  
Nafiseh Falahi ◽  
Farshid Abdi
Keyword(s):  
Risk Management ◽  
Product Development ◽  
New Product Development ◽  
Small Sample Size ◽  
New Product ◽  
Small Sample ◽  
Content Type ◽  
Total Performance ◽  
The Relationship ◽  
Npd Performance

Purpose The principal aim of this study is to investigate the relationship between technological, marketing, organizational and commercialization risk management on new product development (NPD) performance. Design/methodology/approach Based on questionnaire, the data were collected from a sample of general automotive industry in Iran. Based on theoretical considerations, a model was proposed and descriptive statistic and hierarchical regression were used to measure the relationship between risk management factors and NPD performance. Findings Data analysis revealed that if organization can amplify their knowledge and information about risk and main factors that affect NPD process, not only can they do their work better but can also increase their ability to predict future happenings that affect performance. Research limitations/implications First, due to the relatively small sample size, caution should be exercised when interpreting the results. Second, the data were collected from automotive producer in Iran, which may restrict to some extent generalizability of the findings. Practical implications The results suggest that managers should consider more attention to risk management. If managers spread the risk management in all aspects of the NPD project, total performance will be increased and it can develop the probability of NPD success. Also organizations should perform great market research due to best commercialization. Originality/value Past researches have presented complete information about NPD process. But identifying and considering the effect of the risk management parameters that are connected to the NPD process were the main thrusts to perform the study. In this paper, based on past research about risk management of NPD, the extra aspect of process that can improve total performance of NPD has been examined.

Optic pathway glioma infiltrating into somatostatinergic pathways in a young boy with gigantism

1994 ◽  
Vol 81 (4) ◽  
pp. 595-600 ◽  
Author(s):  
Thomas J. Manski ◽  
Charles S. Ha worth ◽  
Bertrand J. Duval-Arnould ◽  
Elisabeth J. Rushing
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Optic Pathway Glioma ◽  
Optic Pathway ◽  
Resonance Imaging ◽  
Content Type ◽  
Hyperintense Signal ◽  
Immunocytochemical Studies ◽  
Stereotactic Biopsies ◽  
Fine Print

✓ The authors report gigantism in a 16-month-old boy with an extensive optic pathway glioma infiltrating into somatostatinergic pathways, as revealed by magnetic resonance imaging and immunocytochemical studies. Stereotactic biopsies of areas showing hyperintense signal abnormalities on T2-weighted images in and adjacent to the involved visual pathways provided rarely obtained histological correlation of such areas. The patient received chemotherapy, which resulted in reduction of size and signal intensity of the tumor and stabilization of vision and growth velocity.

The categorization of expatriates and the support offered by host country nationals

2016 ◽  
Vol 4 (1) ◽  
pp. 18-43 ◽  
Author(s):  
Shirley C. Sonesh ◽  
Angelo S. DeNisi
Keyword(s):  
Host Country ◽  
Small Sample Size ◽  
Small Sample ◽  
Content Type ◽  
Host Country Nationals ◽  
Group Members ◽  
Expatriate Assignments ◽  
The Right ◽  
National Stereotypes

Purpose – Although several authors have suggested that host country nationals (HCNs) play an important role in the management of expatriates (e.g. Toh and DeNisi, 2003; Farh et al., 2010), research has also suggested that this relationship is not always good, and the flow of critical information to expatriates can be limited. This is especially true when HCNs categorize the expatriates as “out-group” members. The purpose of this paper is to examine potential determinants of categorization decisions as well as potential outcomes related to expatriate socialization. Design/methodology/approach – The paper employs a dyadic survey approach to determine the antecedents to expatriate categorization and HCN socialization behaviors from the perspective of both the expatriate and HCN. Findings – The results of survey data from 65 expatriate-HCN dyads indicated that expatriate ethnocentrism and the salience of the expatriates’ nationality were important predictors of categorization, but that categorization was related to only one dimension of socialization. However, affect was found to play a role in predicting socialization behaviors. Research limitations/implications – There is potential selection bias since expatriates chose HCNs as respondents, but results suggested this was not a serious problem. Other limitations include a relatively small sample size and the fact that a number of contextual issues such as national stereotypes and MNC strategy, are not controlled for. Practical implications – Implications of these findings for the successful management of expatriate assignments include sending over expatriates with the right relational skills, and those low in ethnocentrism, rather than just the right technical skills. Originality/value – The present study was one of the first to empirically test the potential role of categorization in the process of socialization.

Application of magnetic resonance neurography in the evaluation of patients with peripheral nerve pathology

1996 ◽  
Vol 85 (2) ◽  
pp. 299-309 ◽  
Author(s):  
Aaron G. Filler ◽  
Michel Kliot ◽  
Franklyn A. Howe ◽  
Cecil E. Hayes ◽  
Dawn E. Saunders ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Time Course ◽  
Spin Echo ◽  
Fast Spin Echo ◽  
Mr Neurography ◽  
Magnetic Resonance Neurography ◽  
Cross Sectional ◽  
Content Type ◽  
Direct Nerve ◽  
Fine Print

✓ Currently, diagnosis and management of disorders involving nerves are generally undertaken without images of the nerves themselves. The authors evaluated whether direct nerve images obtained using the new technique of magnetic resonance (MR) neurography could be used to make clinically important diagnostic distinctions that cannot be readily accomplished using existing methods. The authors obtained T2-weighted fast spin—echo fat-suppressed (chemical shift selection or inversion recovery) and T1-weighted images with planes parallel or transverse to the long axis of nerves using standard or phased-array coils in healthy volunteers and referred patients in 242 sessions. Longitudinal and cross-sectional fascicular images readily distinguished perineural from intraneural masses, thus predicting both resectability and requirement for intraoperative electrophysiological monitoring. Fascicle pattern and longitudinal anatomy firmly identified nerves and thus improved the safety of image-guided procedures. In severe trauma, MR neurography identified nerve discontinuity at the fascicular level preoperatively, thus verifying the need for surgical repair. Direct images readily demonstrated increased diameter in injured nerves and showed the linear extent and time course of image hyperintensity associated with nerve injury. These findings confirm and precisely localize focal nerve compressions, thus avoiding some exploratory surgery and allowing for smaller targeted exposures when surgery is indicated. Direct nerve imaging can demonstrate nerve continuity, distinguish intraneural from perineural masses, and localize nerve compressions prior to surgical exploration. Magnetic resonance neurography can add clinically useful diagnostic information in many situations in which physical examinations, electrodiagnostic tests, and existing image techniques are inconclusive.

Early changes measured by magnetic resonance imaging in cerebral blood flow, blood volume, and blood-brain barrier permeability following dexamethasone treatment in patients with brain tumors

1999 ◽  
Vol 90 (2) ◽  
pp. 300-305 ◽  
Author(s):  
Leif Østergaard ◽  
Fred H. Hochberg ◽  
James D. Rabinov ◽  
A. Gregory Sorensen ◽  
Michael Lev ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Magnetic Resonance ◽  
Brain Tumors ◽  
Mr Imaging ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Clinical Effects ◽  
Content Type ◽  
Fine Print

Object. In this study the authors assessed the early changes in brain tumor physiology associated with glucocorticoid administration. Glucocorticoids have a dramatic effect on symptoms in patients with brain tumors over a time scale ranging from minutes to a few hours. Previous studies have indicated that glucocorticoids may act either by decreasing cerebral blood volume (CBV) or blood-tumor barrier (BTB) permeability and thereby the degree of vasogenic edema.Methods. Using magnetic resonance (MR) imaging, the authors examined the acute changes in CBV, cerebral blood flow (CBF), and BTB permeability to gadolinium-diethylenetriamine pentaacetic acid after administration of dexamethasone in six patients with brain tumors. In patients with acute decreases in BTB permeability after dexamethasone administration, changes in the degree of edema were assessed using the apparent diffusion coefficient of water.Conclusions. Dexamethasone was found to cause a dramatic decrease in BTB permeability and regional CBV but no significant changes in CBF or the degree of edema. The authors found that MR imaging provides a powerful tool for investigating the pathophysiological changes associated with the clinical effects of glucocorticoids.

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