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S Mussurakis

Publications and source records attributed to S Mussurakis.

At least 19 recordsLinked to original sources
PubMed1998

Primary breast abnormalities: selective pixel sampling on dynamic gadolinium-enhanced MR images.

PURPOSE: To evaluate a region-of-interest (ROI) analytic method that involves selective sampling of pixels within predetermined ranges of contrast material enhancement values ("thresholding") on magnetic resonance (MR) images of primary breast abnormalities. MATERIALS AND METHODS: Dynamic gadolinium-enhanced MR images were obtained in 105 women. ROIs were drawn to outline the full extent of lesions. Relative signal intensity increase was determined on a pixel-by-pixel basis on 1- and 2-minute postcontrast images, as was the maximum relative signal intensity increase. Thresholding was used to analyze each ROI, with the upper boundary defined by the highest pixel value and lower boundaries of 0%-100%. RESULTS: Seventy-one invasive carcinomas and 37 benign lesions were analyzed. Narrower thresholding (i.e., larger percentage) resulted in an increase in all enhancement ratios (P < .0005). The enhancement ratio on 1-minute postcontrast images differed between benign lesions and carcinomas (P < .0005), but there were no significant differences in 2-minute and maximum ratios. Mean enhancement differences between benign and malignant lesions increased with narrower thresholding, but variability also increased linearly. Results of receiver operating characteristic analysis showed that thresholding did not affect the diagnostic usefulness of enhancement ratios. CONCLUSION: Contrary to current opinion, selective sampling of the most enhancing areas of breast abnormalities may not provide any diagnostic advantage over the use of easily drawn, lesion-encompassing ROIs.

Biopsy↗
PubMed1997

Dynamic MR imaging of the breast combined with analysis of contrast agent kinetics in the differentiation of primary breast tumours.

OBJECTIVE: To assess dynamic Gd-DTPA-enhanced magnetic resonance (MR) imaging in the diagnosis of primary breast pathology, and to test the hypothesis that analysis of contrast agent kinetics increases specificity. METHODS: Forty-seven women underwent breast MR imaging using three-dimensional and dynamic spoiled gradient-recalled sequences. Image interpretation was based on the evaluation of lesion conspicuity, signal intensity, contour and enhancement pattern from the static acquisitions. Assessment of contrast kinetics was based on pixel-by-pixel analysis of the dynamic data. A two-compartment model described by three parameters (amplitude of uptake, exchange rate and washout rate), and a three-compartment model described by two parameters (permeability and exchange rate) were used. Regions of interest were drawn for all lesions found in the dynamic sections. Mean regional pixel values were calculated for each parameter and tested for diagnostic efficacy. RESULTS: Twenty-two malignant and 36 benign lesions were examined. Fibroadenomas accounted for 86% of the benign tumours. Image interpretation had a sensitivity of 0.95 and specificity of 0.86. The fat-suppressed post-contrast images permitted good visualization of the contour and matrix characteristics of fibroadenomas, but all non-fibroadenomatous benign lesions were classified as indeterminate or suspicious. Significant differences were found between benign and malignant lesions in the amplitude of uptake (P = 0.0008) and exchange rate (P < 0.00005) of the two-compartment model, and permeability (P=0.0001) and exchange rate (P < 0.00005) of the three-compartment model. However, image interpretation was superior to the isolated use of quantitative indices (P=0.02). The most discriminating parameters were the exchange rates of both models, with no significant difference between them. CONCLUSION: Assessment of lesion morphology is essential and probably sufficient for the differentiation of fibroadenomas from malignant tumours. However, specificity of conventional MR imaging may be much lower for other types of primary benign breast pathology. Analysis of Gd-DTPA kinetics improves the specificity obtained using simple enhancement measurements and can be used to produce parametric images that provide information about lesion heterogeneity, permeability and vascularity.

Adult↗
PubMed1997

MR imaging of primary non-Hodgkin's breast lymphoma. A case report.

In this report we describe the MR imaging findings, including dynamic data, in a patient with primary non-Hodgkin's lymphoma of the breast. The precontrast T1-weighted sequence showed several hypointense, ill-defined, non-spiculated masses. In the T2-weighted images the masses showed a hyperintense halo. In the dynamic and postcontrast sequences all lesions enhanced markedly, and a further large mass was discovered. In comparison to mammography and sonography, only MR imaging identified the multicentric extent of the tumour. Differentiation from invasive cancer, based on either MR or conventional imaging features, was not possible.

Biopsy, Needle↗
PubMed1997

Prediction of axillary lymph node status in invasive breast cancer with dynamic contrast-enhanced MR imaging.

PURPOSE: To determine if magnetic resonance (MR) imaging can be used to predict axillary lymph node status in patients with breast cancer. MATERIALS AND METHODS: Fifty-one women with primary invasive breast cancer underwent dynamic contrast material-enhanced MR imaging of the breast Region-of-interest (ROI) analysis was performed on parametric images obtained with kinetic modeling of the data. Large and automated ROIs were selected. Typical enhancement ratios that represented the relative increase in mean pixel signal intensity were calculated for each ROI. Stepwise logistic regression analysis was applied to identify prognostic factors of axillary node status. Receiver operating characteristic analysis was performed and a Brier score and calibration curve were calculated to assess the diagnostic efficacy and predictive capability of the logistic regression model. RESULTS: The maximum enhancement ratio of the automated ROI was found to be the strongest predictor of node status (P < .001). Patient age (P = .007) and ROI size (P = .045) were also significant predictor variables. The model showed good accuracy (area beneath the fitted binormal receiver operating characteristic curve [Az] = 0.90; Brier score, 0.133). In 12 (24%) of the patients, a less than 5% or greater than 95% probability of positive-node status was correctly identified. CONCLUSION: The suggested predictive model may decrease the need for surgical staging of the axilla in patients with breast cancer.

Adult↗
PubMed1997

Dynamic MR imaging of invasive breast cancer: correlation with tumour grade and other histological factors.

The purpose of this study was to explore the association between dynamic MR enhancement characteristics and histopathological prognostic factors of invasive breast cancer. 53 women with primary invasive breast cancer underwent dynamic contrast enhanced breast MRI. Region of interest (ROI) analysis was performed on synthetic images obtained by kinetic modelling of the dynamic data. Operator-defined, large ROIs and computer-defined, 9-pixel ROIs were selected for each tumour. The relative increase in mean ROI pixel intensity was expressed in the form of enhancement ratios. Univariate and multivariate analyses were performed to explore the association of these ratios with standard histological factors, including tumour size, histopathological classification, histological grade, the presence of extensive in situ component and lymphovascular invasion, multifocal disease, and axillary lymph node status. All enhancement ratios showed significant differences between node-positive and node-negative tumours (max. p = 0.002). However, automated ROI ratios showed less overlap between node-positive and node-negative carcinomas than did large ROI ratios. A strongly significant association was observed between all automated ROI enhancement ratios and histological tumour grade (max. p = 0.001). Based on stepwise multiple regression analysis, node status and histological grade were the only histopathological factors with a significant independent effect on the enhancement characteristics. In summary, there is a strong association between dynamic MR characteristics and two important prognostic markers of invasive breast cancer, namely axillary node status and histological grade. This may allow MRI to be used in pre-operative predictions of tumour behaviour and biological activity.

Adult↗
PubMed1996

Case report: MR imaging of juvenile papillomatosis of the breast.

Juvenile papillomatosis of the breast is a benign, localized proliferative condition encountered mainly in young women. We describe the contrast-enhanced MR imaging findings, including dynamic data, of a patient with histologically proven juvenile papillomatosis of the breast. The pre-contrast T1 weighted sequence showed a hypointense lobulated mass which enhanced markedly in the post-contrast images. In the dynamic sequence the lesion showed a benign enhancement profile. The most specific feature was the presence of multiple small internal cysts, best shown on the T2 weighted images. This constellation of findings should suggest juvenile papillomatosis.

Adult↗
PubMed1996

Observer variability in the interpretation of contrast enhanced MRI of the breast.

The purpose of this study was to determine observer variability in the interpretation of contrast enhanced breast MRI and to evaluate its effect on the detection and differentiation of breast cancer. 57 women underwent breast MRI using spin echo and dynamic spoiled gradient-recalled sequences. Images were independently reviewed by three radiologists, two experienced and one newly trained in breast MRI interpretation. One of the experienced readers reviewed all examinations twice. Interpretation was based on lesion conspicuity, signal intensity, contour and enhancement pattern. Contrast uptake was assessed using region of interest (ROI) analysis of the dynamic images and calculation of a maximum enhancement index. Sensitivity and specificity in the diagnosis of malignancy irrespective of disease extent, and in the diagnosis of multifocal malignancy were estimated. 113 lesions were reported. Kappa coefficient estimations showed only a moderate agreement between the two experienced readers in rating morphological characteristics; the agreement between the newly trained reader and the experienced readers was even worse. Moreover, there was significant interobserver and intraobserver variation in the enhancement index measurements. Weighted kappa values indicated good agreement between the experienced readers in lesion and overall interpretation, excellent intraobserver agreement, but substantial disagreement between the newly trained reader and both experienced readers. All readers showed good sensitivity in cancer detection, but specificity was substantially lower. There is significant observer variability and a substantial learning curve in the interpretation of breast MRI, and variability in the ROI analysis of dynamic data. Further efforts to improve the reliability of ROI analysis and image interpretation are needed to help MRI realise its full potential in the clinical management of breast cancer.

Adult↗
PubMed1995

Dynamic contrast-enhanced magnetic resonance imaging of the breast combined with pharmacokinetic analysis of gadolinium-DTPA uptake in the diagnosis of local recurrence of early stage breast carcinoma.

RATIONALE AND OBJECTIVES: This study was designed to assess the efficacy of dynamic contrast-enhanced magnetic resonance imaging (MRI) of the breast combined with pharmacokinetic analysis of gadolinium (Gd)-DTPA uptake in the diagnosis of local recurrence of early stage breast carcinoma. METHODS: Fifty women treated with breast-conserving surgery and radiotherapy underwent breast MRI. Dynamic magnetic resonance data obtained at four preselected slice locations were analyzed to examine Gd-DTPA uptake based on a pharmacokinetic model using three parameters: wash-in rate, wash-out rate, and amplitude of uptake. Synthetic images were produced from the above parameters and their derivatives--maximum uptake and reciprocal of half the time to maximum. For each region of interest (ROI), median parameter values were calculated. The mean pixel signal intensity of each ROI was plotted against time, and an enhancement index was determined. RESULTS: Sixty ROIs were selected: 49 lesions were benign, and 11, malignant. Significant differences between benign and malignant lesions were found for the enhancement index (P < 0.0001), maximum uptake (P < 0.0001), amplitude of uptake (P < 0.0001), wash-in rate (P = 0.03), wash-out rate (P = 0.01), and the reciprocal of half the time to maximum (P = 0.0005). The respective sensitivities and specificities were as follows: for the enhancement index, 1.00 and 0.96; for maximum uptake, 1.00 and 0.96; for amplitude of uptake, 0.91 and 0.94; for wash-in rate 0.82 and 0.47; for wash-out rate 0.91 and 0.59; and for the reciprocal of half the time to maximum, 1.00 and 0.51. CONCLUSIONS: Dynamic scanning proved essential for the detection and differential diagnosis of local tumor recurrence. Pharmacokinetic analysis of Gd-DTPA uptake can be used to produce parametric images that retain the spatial resolution of the original images while providing additional information about lesion permeability and vascularity, and helping to avoid the observer variability associated with ROI analysis.

Adult↗
PubMed1995

Patterns of integration and clinical value of voiding cystourethrography in the work-up of urinary tract infection in children.

OBJECTIVE: To evaluate the patterns of integration and the clinical value of voiding cystourethrography (VCUG) in the imaging work-up of children with urinary tract infection (UTI). METHODS: We reviewed the medical records of a consecutive sample of 80 children that underwent VCUG as part of routine investigation for UTI. We assessed the following: the appropriateness of integration of VCUG in the patient work-up as determined by the presence or absence of a valid indication for VCUG in the specific clinical situation encountered, the correct timing of the examination and interpretation of its result; the change in clinical management initiated by the result of the test, and the reassurance conferred to the clinician. RESULTS: Sixty-nine percent of the VCUG examinations were judged appropriately integrated, 14% of the examinations inappropriately integrated, while for the rest of the patients (17%) the appropriateness of integration of the test was rated as unclear. The change in patient management attributable to the VCUG result could be categorized as: no change (15%); decision to end the imaging investigation of the patient (39%); decision to end all investigations, and prophylactic or therapeutic interventions (17%); decision to discontinue chemoprophylaxis (1%); decision to end the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (5%); decision to continue the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (15%), and decision to operate or help in planning the surgical treatment required (8%). CONCLUSION: The findings show the need for an increased effort to minimize overuse of VCUG in pediatric UTI. Future interventions should focus on issues of clinical efficacy of the method that may have not been emphasized sufficiently.

Child↗
PubMed1994

The appropriateness of use and the clinical impact of micturating cystourethrography in paediatric practice.

STUDY OBJECTIVE: To determine the appropriateness of use and the clinical impact of micturating cystourethrography (MCU) in paediatric practice. DESIGN: Retrospective medical record review. SETTING: A major teaching children's hospital in the Trent region. PATIENTS: Consecutive sample of 120 children undergoing MCU during 1991-1992, identified from the radiology records. MAIN OUTCOME MEASURES: The referring clinician's reasons for requesting an MCU; the clinical management plan pursued before and after the MCU, and the change in management initiated by the result of the examination; the appropriateness of use of the test, as determined by the presence or absence of a valid indication for MCU in the specific clinical situation. RESULTS: The change in patient management attributable to the MCU result could be categorized as: no change (19%); decision to end the imaging investigation of the patient (33%); decision to end all investigations, and prophylactic or therapeutic interventions (16%); decision to discontinue chemoprophylaxis (2%); decision to end the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (6%); decision to continue the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (13%); and decision to operate or help in planning the surgical treatment required (11%). Inappropriate use of the test was observed in 20% of the cases. CONCLUSIONS: This study provides a basis for understanding the use of MCU in paediatric practice. The findings that 19% of the cystourethrograms had no appreciable effect, and that 20% of the examinations were used inappropriately show the need for increased effort to minimize overuse of the test.

Child↗
PubMed1994

Authorship ethics in the radiological sciences.

The written communication of new ideas and current developments is a crucial part of the progress of radiological sciences. Research results cannot be incorporated into the body of scientific knowledge, unless they are published. In radiology, questions on authorship ethics have received limited attention. Among the topics discussed in this article are the incentives that stimulate radiologists to write and the obstacles to successful authorship. Practices causing concern to editors, authors and readers are examined, such as the excessive growth through recent years in the numbers of authors per paper, unjustified co-authorships, wasteful publication practices and fraudulent research. The relationship between the abuses of authorship and the pressure exerted on researchers to publish is exemplified. Further issues addressed include the responsibilities of authors, the proposed principles for authorship, the determination of the sequence of authors in multi-authored papers and the concept of publication credit. The editor's role in preventing unethical authorship is examined and emphasis is placed on the proposals that have been made to achieve the required reforms by eradicating the publish or perish mentality.

Authorship↗
PubMed1994

Financial support for research in radiology: a survey of original investigations published in the AJR and Radiology.

OBJECTIVE: This study was done to determine how often the original research published in AJR and Radiology is formally funded by external sources of explicit intramural institutional research grants and to explore the association of financial support with the subspecialty field; type of research (clinical vs basic); number of coauthors; number of departments, nonradiology departments, and institutions participating per paper; country of origin; and citation impact of investigations. MATERIALS AND METHODS: All 736 original articles published in AJR and Radiology in 1990 were surveyed. The following information was abstracted: the presence or absence of specific funding, as determined from the footnote acknowledgments given by the authors (for the 560 papers from the United States, financial support was further classified according to the funding agency listed first); the subspecialty field of research, as determined from the indexing of the paper in the table of contents; the type of research (clinical, basic, combined clinical and basic); the number of coauthors; the number of departments, nonradiology departments, and institutions participating; the first author's department (radiology, medicine, surgery, medical physics); the first author's institution (university-affiliated medical institution, medical institution not affiliated with a university, National Institutes of Health center); and the country of the first author's institution. Research impact was assessed by using citation counts. RESULTS: Only 17% of the surveyed studies were formally funded. The 95 funded studies from the United States were federally sponsored (63%), funded by private industry (11%), supported by nonprofit foundations (16%), or funded from explicit intramural institutional monies (11%). Funding was significantly related to the subspecialty field (p = .00007), the type of research (p < .000001), and the category of the first author's department (p < .000001). When papers on contrast media research were excluded from the analysis, the association of funding to the field of research became statistically insignificant (p = .21). Financial support was not significantly related to the category of the first author's institution (p = .71) or to whether the research was done in the United States (p = .71). A statistically significant positive association was found between funding and the number of coauthors (p = .013), the number of departments (p = .049), nonradiology departments (p = .004), and institutions participating per paper (p = .018). Funded papers were cited more extensively than nonfunded papers (p = .015). CONCLUSION: Only a small percentage of radiology research attracts formal, especially extramural, financial support. This should be a cause for concern. As the informal funding of investigations from redirected clinical revenues is diminishing, action will be required to procure funds to support the radiology research necessary for the vitality of the specialty.

Bibliographies as Topic↗
PubMed1993

Do citation conventions influence coauthorship patterns?

The main purpose of contributing to radiologic publications should be to advance the state of knowledge or increase awareness of issues useful in radiologic practice and research. According to experts on medical writing, however, the pride of discovery and the communication of scientific information for the enrichment of public knowledge are not the sole motives of authors. Success in the profession, prestige, and tenure have long been associated with prolific publishing in peer-reviewed journals. A proof of this association is the documented rise through recent years in the number of authors per paper. The phenomenon has been attributed in part to the increasing complexity and labor intensiveness of biomedical research, but this speculation remains unproved, and it is believed that often the allocation of authorship has a volitional component.

Authorship↗
PubMed1993

Coauthorship trends in the leading radiological journals.

Coauthorship trends have received limited attention in radiology. This paper examines the author inflation phenomenon in 12 leading radiological peer-reviewed journals and seeks explanations for the rise in multiple authorship. MEDLINE was searched from 1966 through 1991, and the indexed scientific material (67,758 articles) of the eligible core journals was analysed. During this 26-year period the average number of authors per original article (including case reports) doubled, increasing from 2.2 in 1966 to 4.4 in 1991. The linear regression model fitting the data was strongly significant, although since the late 1980s the rate of the coauthorship rise started to decrease. There was considerable variation in coauthorship patterns between journals. Other factors, such as the contributors' country, were also noted to influence coauthorship. The increasing complexity of radiological research explains in part the rise in multiple-author papers, but the main cause must undoubtedly be the excessive pressure to publish. Among the topics discussed are the incentives that stimulate radiologists to write, the dynamics of coauthorship, and the proposals made to standardize the requirements for authorship and to shift the emphasis from quantity of publication to quality.

Authorship↗
PubMed1990

Compression ultrasonography as a reliable imaging monitor in deep venous thrombosis.

Our experience at Hippokration Athens Hospital with high-resolution real-time ultrasonography of the deep veins of the lower extremities is described, drawn from the results of a prospective comparative study of 65 patients. We used a combination of sonography and contrast venography for the detection of deep venous thrombosis (DVT). Of the study group, 33 had clinically suspected DVT, 20 were asymptomatic high-risk patients, while 12 with varicosities of the leg and scheduled for saphenectomy were examined preoperatively for deep venous patency confirmation. For all patients, venography, the reference method, was performed within 12 hours of the ultrasound scan. Since 29 of the examinations were bilateral, the total number of extremities studied was 94. The sonographic criteria analyzed were the intraluminal echogenicity and the venous compressibility with the ultrasound transducer probe. In addition, the response of the common femoral vein to the Valsalva maneuver was studied. Among these three criteria, compressibility was by far the most accurate. Noncompressible abnormal veins were noted in all of the 24 extremities with proximal thrombosis and in six of the 12 with thrombosis limited to the calf veins. Thus, the sensitivity of the compressibility criterion was 100 per cent for proximal and 50 per cent for isolated calf venous thrombosis (83 per cent). All venographically patent veins were fully compressible (specificity, 100 per cent). Abnormal intraluminal echoes were found in 18 of the 36 extremities with thrombosis but not in those with negative findings on venography. Sensitivity of intraluminal echogenicity was, therefore, 50 per cent and specificity, 100 per cent. For the Valsalva criterion, the standard lower normal limit of 10 per cent was applied, leading to 40 per cent sensitivity and 93 per cent specificity rates. In comparison with venography, ultrasonography underestimated the extent of thrombosis in 60 per cent of the true-positive examinations, although never to a clinically significant degree. In conclusion, compression ultrasonography, a technique based upon the unique criterion of venous compressibility, is a highly accurate and objective noninvasive diagnostic method, and is also suitable as a screening test. We urge clinicians to support their therapeutic decisions concerning the management of DVT with it.

Adult↗