[Show abstract][Hide abstract] ABSTRACT: Many computed tomography (CT) studies have reported that lipid-rich, presumably rupture-prone atherosclerotic plaques can be characterized according to their Hounsfield Unit (HU) value. However, the published HU-based characterization criteria vary considerably. The present study aims to systematically analyze these values and empirically derive a hierarchical classification of the HU-based criteria which can be referred in clinical situation.
A systematic search in PubMed and Embase for publications with HU-criteria to characterize lipid-rich and fibrous atherosclerotic plaques resulted in 36 publications, published between 1998 and 2011. The HU-criteria were systematically analyzed based on the characteristics of the reporting study. Significant differences between HU-criteria were checked using Student's t-test. Subsequently, a hierarchical classification of HU-criteria was developed based on the respective study characteristics.
No correlation was found between HU-criteria and the reported lumen contrast-enhancement. Significant differences were found for HU-criteria when pooled according to the respective study characteristics: examination type, vessel type, CT-vendor, detector-rows, voltage-setting, and collimation-width. The hierarchical classification resulted in 21 and 22 CT attenuation value categories, for lipid-rich and fibrous plaque, respectively. More than 50% of the hierarchically classified HU-criteria were significantly different.
In conclusion, variations in the reported CT attenuation values for lipid-rich and fibrous plaque are so large that generalized values are unreliable for clinical use. The proposed hierarchical classification can be used to determine reference CT attenuation values of lipid-rich and fibrous plaques for the local setting.
PLoS ONE 09/2013; 8(9):e73460. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the optimal cutoff of choline (Cho) concentration in quantitative multivoxel magnetic resonance (MR) spectroscopic data to safely prove benignancy in breast lesions.
The study was institutional review board approved, and informed consent was obtained from each patient. Between July 2009 and July 2010, multivoxel MR spectroscopy was performed in 24 consecutive patients with 25 breast lesions assessed as Breast Imaging Reporting and Data System 3 or 4 and larger than 1 cm in diameter at mammography. Two-dimensional point-resolved spatially localized spectroscopy chemical shift imaging was first performed without signal suppression (repetition time msec/echo time msec, 1500/30) as reference measurement and was performed subsequently with suppression of water and fat signals (1500/135) to detect Cho. Differences in mean and highest Cho concentration in the breast lesions were tested for significance by using the independent sample t test. The final diagnosis was confirmed with pathologic findings.
Fourteen of 25 breast lesions were malignant. The mean Cho concentration varied between 0.3 and 1.3 mmol/L (0.84 mmol/L ± 0.32 [standard deviation]) in benign lesions and between 1.3 and 9.5 mmol/L (3.10 mmol/L ± 2.21) in malignant lesions. The highest Cho concentrations in benign and malignant lesions were 0.4-1.5 mmol/L (1.19 mmol/L ± 0.33) and 1.7-11.8 mmol/L (4.08 mmol/L ± 2.81), respectively. Mean and highest Cho concentrations in benign and malignant breast lesions differed significantly (P = .02 for both).
The study, in a relatively small patient population, shows that quantitative multivoxel MR spectroscopy can be applied to exclude benign breast lesions from further invasive diagnostic work-up with the implementation of a Cho concentration of 1.5 mmol/L or lower as a cutoff. Further larger studies will be needed to confirm these results.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the additional value of computer-aided detection (CAD) in breast MRI by assessing radiologists' accuracy in discriminating benign from malignant breast lesions.
A literature search was performed with inclusion of relevant studies using a commercially available CAD system with automatic colour mapping. Two independent researchers assessed the quality of the studies. The accuracy of the radiologists' performance with and without CAD was presented as pooled sensitivity and specificity.
Of 587 articles, 10 met the inclusion criteria, all of good methodological quality. Experienced radiologists reached comparable pooled sensitivity and specificity before and after using CAD (sensitivity: without CAD: 89%; 95% CI: 78-94%, with CAD: 89%; 95%CI: 81-94%) (specificity: without CAD: 86%; 95% CI: 79-91%, with CAD: 82%; 95% CI: 76-87%). For residents the pooled sensitivity increased from 72% (95% CI: 62-81%) without CAD to 89% (95% CI: 80-94%) with CAD, however, not significantly. Concerning specificity, the results were similar (without CAD: 79%; 95% CI: 69-86%, with CAD: 78%; 95% CI: 69-84%).
CAD in breast MRI has little influence on the sensitivity and specificity of experienced radiologists and therefore their interpretation remains essential. However, residents or inexperienced radiologists seem to benefit from CAD concerning breast MRI evaluation.
European Radiology 03/2011; 21(8):1600-8. · 4.34 Impact Factor
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[Show abstract][Hide abstract] ABSTRACT: Women with familial or genetic aggregation of breast cancer are offered screening outside the population screening programme. However, the possible benefit of mammography screening could be reduced due to the risk of radiation-induced tumours. A systematic search was conducted addressing the question of how low-dose radiation exposure affects breast cancer risk among high-risk women.
A systematic search was conducted for articles addressing breast cancer, mammography screening, radiation and high-risk women. Effects of low-dose radiation on breast cancer risk were presented in terms of pooled odds ratios (OR).
Of 127 articles found, 7 were selected for the meta-analysis. Pooled OR revealed an increased risk of breast cancer among high-risk women due to low-dose radiation exposure (OR = 1.3, 95% CI: 0.9- 1.8). Exposure before age 20 (OR = 2.0, 95% CI: 1.3-3.1) or a mean of ≥5 exposures (OR = 1.8, 95% CI: 1.1-3.0) was significantly associated with a higher radiation-induced breast cancer risk.
Low-dose radiation increases breast cancer risk among high-risk women. When using low-dose radiation among high-risk women, a careful approach is needed, by means of reducing repeated exposure, avoidance of exposure at a younger age and using non-ionising screening techniques.
European Radiology 11/2010; 20(11):2547-56. · 4.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To calculate the sensitivity and specificity of computed tomographic (CT) angiography in the diagnosis of cerebral aneurysms in patients with acute subarachnoid hemorrhage (SAH) at presentation.
A systematic search for relevant studies was performed of the PubMed/MEDLINE and EMBASE databases. Two reviewers independently assessed the methodologic quality of each study by using the Quality Assessment of Diagnostic Accuracy Studies tool. The inclusion criteria were met by 50 studies. Heterogeneity was tested, and the presence of publication bias was visually assessed (by using a funnel plot). A meta-analysis of the reported sensitivity and specificity of each study with 95% confidence intervals (CIs) was performed on a per-patient level.
Concerning sensitivity, the selected studies showed moderate heterogeneity. For specificity, low heterogeneity was observed. Moderate-heterogeneity studies that investigated only sensitivity or specificity were excluded from the pooled analyses by using a bivariate random effects model. The majority of the studies (n = 30) used a four-detector row CT scanner. The studies had good methodologic quality. Pooled sensitivity was 98% (95% CI: 97%, 99%), and pooled specificity was 100% (95% CI: 97%, 100%). Potential sources of variability among the studies were variations in the methodologic features (quality score), CT examination procedure (number of rows on the multidetector CT scanner), the standard of reference used, and the prevalence of ruptured intracranial aneurysms. There was evidence for publication bias, which may have led to overestimation of the diagnostic accuracy of CT angiography.
Multidetector CT angiography can be used as a primary examination tool in the diagnostic work-up of patients with SAH.
[Show abstract][Hide abstract] ABSTRACT: For women with a BRCA1 or BRCA2 mutation or a strong family history of breast cancer, there is no clear estimation of the risk of tumour induction versus the beneficial effects of mammography screening available. This study aims to validate the Simulation Model on Radiation Risk and breast cancer Screening (SiMRiSc) model in these women, which can provide information on the benefits and risks of screening for breast cancer for various screening scenarios.
The simulation model for breast cancer screening was developed and the values for model parameters including cancer induction due to radiation were derived from the literature. The simulation model was validated by comparing the outcome data of the model with the data from three published screening studies of women with an increased hereditary breast cancer risk. A sensitivity analysis was used to estimate the error margins of the outcome data and to analyse the sensitivity of the simulation model to each parameter.
The model predicted 71+/-4% of the reported tumours. When excluding the excess number of incident tumours detected in the first screening round, the model predicted 85+/-6% of the tumours reported. The model was most sensitive to changes in the parameters related to lifetime breast cancer risk and sensitivity of mammography.
We conclude that the simulation model is suitable for the provision of accurate benefits' and risks' estimations necessary for the refinement of the screening guidelines for women at an increased risk of breast cancer.
European journal of cancer (Oxford, England: 1990) 11/2009; 46(3):495-504. · 4.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study investigated the impact of a visit from a consulting physician on the patient and the relatives during the euthanasia procedure in The Netherlands. Data on experiences with the consultant's visit were collected from 86 relatives and 3,614 general practitioners, who described their most recent request for euthanasia or physician-assisted suicide. More than three-quarters of the patients experienced the visit as they had expected, or became more positive. Although about 1 out of 5 patients had negative experiences, this study indicates that, in general, a visit from a consulting physician is not perceived to be burdensome for patients.
Death Studies 04/2009; 33(3):199-219. · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Consultation of another physician is one of the requirements for prudent practice. The project 'Support and Consultation on Euthanasia in the Netherlands' (SCEN) is aimed at professionalizing consultation. The objective of this study is to assess whether the quality of consultation was improved through SCEN.
In four districts all general practitioners (GPs) received a pre-test questionnaire approximately six weeks before the start of the project in the period (n=1224, response 71%). In the period from April 2000 to December 2002, all GPs in districts in which SCEN had been implemented received a written post-test questionnaire one and a half years after the start of the project. This post-test questionnaire was returned by 60% of the GPs (n=3614).
In SCEN consultations the attending physicians has no specific relation to the attending physician in 85% of consultations, while this is the case for 31% of other consultations. While before the start of SCEN in 71% of consultations six or seven of the seven criteria for good consultation were met, in SCEN consultations 83% of cases six or seven of these requirements were met. GPS who had consulted a SCEN physician generally were more positive about different aspects than those who consulted another consultant, such as considering the consultant to be able to make an independent judgement (totally agree 74% versus 59%).
Although the quality of consultation appears to be high for both SCEN physicians and other consultants, the SCEN project further contributed to the quality of consultation. Since GPs attach importance to judgement of SCEN physician and have the intention to use it in future, and the quality of consultation stays high over time, this project is expected to maintain its value.
Health Policy 02/2007; 80(1):97-106. · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study investigated the palliative options available when a patient requested euthanasia or physician-assisted suicide (EAS), the extent to which the options were applied, and changes in the patient's wishes.
In an observational study, 3614 general practitioners (GPs) filled in a questionnaire and described their most recent request for EAS (if any) (n = 1,681).
Palliative options were still available in 25% of cases. In these cases options were applied in 63%; in 46% of these cases patients withdrew their request. Medication other than antibiotics, which was most frequently mentioned as a palliative option (67%), and applied most frequently (79%), together with radiotherapy, most frequently resulted in patients withdrawing their request.
GPs include the availability of palliative options in their decision making when considering EAS. The fact that not all options are applied or, if applied, the patient persists in the request is related to autonomy of the patient, the burden on the patient, and medical futility of the option.
Palliative and Supportive Care 01/2007; 4(4):399-406. · 0.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the characteristics of patients who request euthanasia or physician-assisted suicide and whether these characteristics differ among those whose request is granted, those who die before the procedure, those who die before completion of the approval process, those who withdraw their request, and lastly, those whose request is refused by the physician.
All general practitioners in 18 of the 23 Dutch general practitioner districts received a written questionnaire in which they were asked to describe the most recent request for euthanasia or physician-assisted suicide that they had received (response 60%, n=3614).
Of all explicit requests, 44% resulted in euthanasia or physician-assisted suicide. Thirteen percent of patients died before the procedure, 13% died before completion of the approval process, 13% withdrew their request and 12% were refused by the physician. The most prominent symptoms were 'feeling bad', 'tiredness', and 'lack of appetite'. The most frequently mentioned reasons for requesting euthanasia or physician-assisted suicide were 'pointless suffering', 'loss of dignity', and 'general weakness'. The patients' situation met the official requirements for accepted practice best in the group of requests that resulted in euthanasia or physician-assisted suicide and least in the group of refused requests. A lesser degree of competence and less unbearable and hopeless suffering had the strongest associations with the refusal of a request.
The complexity of euthanasia or physician-assisted suicide decision-making is reflected in the fact that, besides granting and refusing a request, 3 other situations could be distinguished. The decisions physicians made, the reasons for their decisions and the way they arrived at their decisions appeared to be based on patient evaluations and on the official requirements for accepted practice.
Nederlands tijdschrift voor geneeskunde 03/2006; 150(5):249-54.
[Show abstract][Hide abstract] ABSTRACT: In the Netherlands physicians are allowed to grant requests for euthanasia or physician-assisted suicide (EAS) if they meet several requirements of due care. According to jurisprudence, a physician is not allowed to end the life of a patient whose request for EAS is based on being 'tired of living', because such a request falls outside the medical domain. Our previous studies have shown that in spite of this, such requests are made approximately 400 times a year.
To learn more about patients who request EAS because they are tired of living, and about factors that influence the decision of the physician.
Questionnaires (n=4842) completed by general practitioners (n=3994).
According to the physicians, 17% of patients who requested EAS were 'tired of living'. Of 139 patients in whose request for EAS being tired of living played a major role, 47% suffered from cancer, 25% suffered from another severe disease and 28% had no severe disease. In all three groups the same three symptoms occurred most frequently, 'feeling bad', 'tired', and 'not active'. Each of these symptoms occurred in more than half of the patients in each group. Most of the requests from patients with cancer were granted, but those from patients who had some other severe disease, or no severe disease at all, were refused. Factors that were related to granting a request were: the presence of unbearable and hopeless suffering, the absence of alternatives, and the absence of depressive symptoms.
Being tired of living can play a major role in requests for EAS, both in the absence and the presence of a severe disease. The high occurrence of symptoms in the absence of a classifiable severe disease implies that physical symptoms are prevalent in this group of patients, leaving the legal requirement for EAS of 'a medical cause' open to interpretation in the more complex medical practice.
Health Policy 11/2005; 74(2):157-66. · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mental health status may be closely related to an instability of intentions toward a premature death, but little is known about such instability following an explicit request for euthanasia or physician-assisted suicide (EAS) and patient characteristics associated with a change of mind.
A questionnaire was sent to 6596 general practitioners in The Netherlands (response rate 60%). Of these, 1681 provided descriptions of the most recent explicit request for EAS they had received in the preceding 18 months.
Symptoms of depression and anxiety were related to a change of mind, but no relationship was found with the total score of the NOSGER Mood Dimension. Multinomial regression analysis revealed that patients who changed their mind had more mental health problems and less mental clarity than those who died by EAS. They also had fewer general health problems, had less unbearable and pointless suffering (according to the physician), were less concerned about loss of dignity and alternative treatment options were more frequently available. A further analysis revealed that mental health problems were more prevalent among patients whose requests were refused than among those who changed their mind. The physicians' evaluations of the reasons why a patient requested EAS were similar to a more objective measure of the patient characteristics.
These findings suggest that mental health status must be carefully assessed, and possible instability of desire must be taken into account in the course of a request for EAS. These results require replication, and future studies should adopt a prospective method.
Psychological Medicine 10/2005; 35(9):1265-74. · 5.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aims of this study were to obtain information about the characteristics of requests for euthanasia and physician-assisted suicide (EAS) and to distinguish among different types of situations that can arise between the request and the physician's decision.
All general practitioners in 18 of the 23 Dutch general practitioner districts received a written questionnaire in which they were asked to describe the most recent request for EAS they received.
A total of 3614 general practitioners responded to the questionnaire (response rate, 60%). Of all explicit requests for EAS, 44% resulted in EAS. In the other cases the patient died before the performance (13%) or finalization of the decision making (13%), the patient withdrew the request (13%), or the physician refused the request (12%). Patients' most prominent symptoms were "feeling bad," "tiredness," and "lack of appetite." The most frequently mentioned reasons for requesting EAS were "pointless suffering," "loss of dignity," and "weakness." The patients' situation met the official requirements for accepted practice best in requests that resulted in EAS and least in refused requests. A lesser degree of competence and less unbearable and hopeless suffering had the strongest associations with the refusal of a request.
The complexity of EAS decision making is reflected in the fact that besides granting and refusing a request, 3 other situations could be distinguished. The decisions physicians make, the reasons they have for their decisions, and the way they arrived at their decisions seem to be based on patient evaluations. Physicians report compliance with the official requirements for accepted practice.
Archives of Internal Medicine 08/2005; 165(15):1698-704. · 13.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the project 'Support and Consultation on Euthanasia in The Netherlands' (SCEN), general practitioners (GPs) receive training in formal consultation and in giving expert advice to colleagues who have questions about euthanasia and physician-assisted suicide (EAS). This study describes the way in which this project was implemented in The Netherlands and how it was received by GPs.
In the period from April 2000 to December 2002, all GPs in the districts in which SCEN had been implemented received a written post-test questionnaire a year and a half after the start of the project. Registration forms were also filled in by the SCEN physicians and the GPs who contacted SCEN. The post-test questionnaire was returned by 60% of the GPs (n = 3614), and registration forms were returned by 86% (n = 3337) of the GPs who contacted SCEN.
The gradual nation-wide implementation of SCEN was completed within the 4-year study period. Almost all GPs were familiar with the project (99%) and most GPs knew what they could contact SCEN for. Most GPs felt supported by the presence of SCEN, and most GPs also had a positive attitude towards consultation and SCEN. GPs who had received an explicit request for EAS, or had performed EAS, often consulted SCEN physicians (71 and 85%, respectively). Reasons for contacting SCEN were: independence (60%), expertise (58%), and accessibility/availability of a consultant (45%). Reasons for not contacting SCEN were: enough other possibilities for counselling and consultation (48%) only at the beginning of the decision-making process (36%), and sufficient knowledge about EAS (22%). Most GPs intended to use SCEN in the future (96%).
The implementation of SCEN has been successful, according to the four steps for successful implementation: awareness, attitude, use and future use. In this respect, linking up with existing networks and good organisation may play an important role. Furthermore, GPs consider it important to have a facility like SCEN which they can contact concerning EAS.
Health Policy 10/2004; 69(3):365-73. · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PURPOSE/AIM
1. To review different CAD-systems in MR mammography. 2. To determine the value of a specific CAD-system for MR mammography 3. To outline the discrimination between benign and malignant breast lesions in MR mammography with and without the use of CAD.
CAD-systems for MRI essentially provide easier ways of interpreting the patterns of contrast enhancement and washout across a series of images. We will discuss CAD-systems, which are either commercially available or institution-specific computer analysis systems, the characteristics and the quality of the different CAD-systems and the discrimination between benign and malignant breast lesions in MRI with and without the use of CAD.
Commercially available or institution-specific CAD-systems are adequate for sensitivity and can efficiently judge MR mammography. CAD-systems have the potential to improve the discrimination of benign from malignant breast lesions at MR imaging. Furthermore, CAD-systems are useful as a tool to supplement the radiologist’s subject interpretation, but should not be a replacement to the radiologist’s assessment.
Radiological Society of North America 2009 Scientific Assembly and Annual Meeting;