[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 01/2013; 8(9):e73460. · 3.73 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. · 3.55 Impact Factor
[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. · 3.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: To compare left ventricular (LV) function assessment using five different software tools on the same dual source computed tomography (DSCT) datasets with the results of MRI.
Twenty-six patients, undergoing cardiac contrast-enhanced DSCT were included (20 men, mean age 59±12 years). Reconstructions were made at every 10% of the RR-interval. Function analysis was performed with five different, commercially available workstations. In all software tools, semi-automatic LV function measurements were performed, with manual corrections if necessary. Within 0-22 days, all 26 patients were scanned on a 1.5 T MRI-system. Bland-Altman analysis was performed to calculate limits of agreement between DSCT and MRI. Pearson's correlation coefficient was calculated to assess the correlation between the different DSCT software tools and MRI. Repeated measurements were performed to determine intraobserver and interobserver variability.
For all five DSCT workstations, mean LV functional parameters correlated well with measurements on MRI. Bland-Altman analysis of the comparison of DSCT and MRI showed acceptable limits of agreement. Best correlation and limits of agreement were obtained by DSCT software tools with software algorithms comparable to MRI software.
The five different DSCT software tools we examined have interchangeable results of LV functional parameters compared to regularly analysed results by MRI. The best correlation and the narrowest limits of agreement were found when the same software algorithm was used for both DSCT and MRI examinations, therefore our advice for clinical practice is to always evaluate images with the same type of post-processing tools in follow-up.
European journal of radiology 11/2010; 80(3):755-66. · 2.65 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: The probability of a mammographic Breast Imaging Reporting and Data System (BI-RADS) 3 lesion being cancer is considered to be less than 2%. Therefore, the work-up of a mammographic BI-RADS 3 lesion should be biopsy or follow-up mammography after 6 months. However, most patients referred for biopsy have benign disease. Although the negative predictive value (NPV) of magnetic resonance imaging (MRI) is highest of all imaging techniques, it is not yet common practice to use breast MRI as a problem-solving modality to exclude patients for further diagnostic work-up. Therefore, in this meta-analysis the usefulness of breast MRI as a problem-solving modality in mammographic BI-RADS 3 lesions is investigated. After a systematic search only 5 out of 61 studies met the inclusion criteria. The NPV in 2 of those studies was reported to be 100%. It was concluded that MRI can be used as an adjunctive tool to mammographic BI-RADS 3 findings to exclude patients for further diagnostic work-up. The other 3 studies assessed the accuracy of MRI in mammographic BI-RADS 3 microcalcifications. These studies reported an NPV of MRI between 76% and 97%. Therefore, MRI cannot be implemented as a diagnostic tool to evaluate mammographic microcalcifications at this time. The first solid data indicate that breast MRI might be useful as a problem-solving modality to exclude patients with non-calcified mammographic BI-RADS 3 lesions for further diagnostic work-up. However, further research is needed to verify these results.
Cancer Imaging 01/2010; 10 Spec no A:S54-8. · 1.59 Impact Factor
[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