A Test of Performance of Breast MRI Interpretation in a Multicentre Screening Study

Objectives: The aim of this study was to assess the consistency and performance of radiologists interpreting breast magnetic resonance imaging (MRI) examinations. Materials and Methods: Two test sets of eight cases comprising cancers, benign disease, technical problems and parenchymal enhancement were prepared from two manufacturers' equipment (X and Y) and reported by 15 radiologists using the recording form and scoring system of the UK MRI breast screening study [(MAgnetic Resonance Imaging in Breast Screening (MARIBS)]. Variations in assessments of morphology, kinetic scores and diagnosis were measured by assessing intraobserver and interobserver variability and agreement. The sensitivity and specificity of reporting performances was determined using receiver operating characteristic (ROC) curve analysis. Results: Intraobserver variation was seen in 13 (27.7%) of 47 of the radiologists' conclusions (four technical and seven pathological differences). Substantial interobserver variation was observed in the scores recorded for morphology, pattern of enhancement, quantification of enhancement and washout pattern. The overall sensitivity of breast MRI was high [88.6%, 95% confidence interval (CI) 77.4-94.7%], combined with a specificity of 69.2% (95% CI 60.5-76.7%). The sensitivities were similar for the two test sets (P=.3), but the specificity was significantly higher for the Manufacturer X dataset (P

Dynamic breast MRI: Image registration and its impact on enhancement curve estimation

A novel algorithm for performing registration of dynamic contrast-enhanced (DCE) MRI data of the breast is presented. It is based on an algorithm known as iterated dynamic programming originally devised to solve the stereo matching problem. Using artificially distorted DCE-MRI breast images it is shown that the proposed algorithm is able to correct for movement and distortions over a larger range than is likely to occur during routine clinical examination. In addition, using a clinical DCE-MRI data set with an expertly labeled suspicious region, it is shown that the proposed algorithm significantly reduces the variability of the enhancement curves at the pixel level yielding more pronounced uptake and washout phases.

Analysis by MRI of Residual Tumor After Radiofrequency Ablation for Early Stage Breast Cancer

OBJECTIVE. The objective of our study was to evaluate the effectiveness of MRI in the detection of possible residual lesions after radiofrequency ablation (RFA) in the treatment of breast cancer. SUBJECTS AND METHODS. We prospectively evaluated 14 patients who had undergone ultrasound-guided core biopsies diagnostic of invasive ductal carcinoma (IDC; range of diameters, 1.0-3.0 cm) and then ultrasound-guided percutaneous RFA with sentinel node biopsy as the primary treatment. Breast MRI was performed 1 week before RFA to evaluate tumor extension and again 3 weeks after RFA to verify the presence of possible residual lesions. Conventional surgical resection of the tumors was performed 1 week after RFA. The MRI findings were compared with histopathologic analyses to confirm the presence or absence of residual tumor. RESULTS. There was no residual enhancement in seven lesions on the postablation breast MRI scans. These findings were confirmed by negative histopathologic findings in the surgical specimens. The MRI scans of five patients showed small areas of irregular enhancement that corresponded to residual lesions. In the two remaining patients, we observed enhancement of almost the entire lesion, indicating that RFA had failed. CONCLUSION. Breast MRI is effective in detecting residual lesions after RFA in patients with IDC.

Magnetization transfer ratio as a predictor of malignancy in breast lesions: Preliminary results

MRI is an important tool for investigating breast cancer. Although recognized as the method of choice for screening highrisk patients, and for other indications the role of MRI for lesion characterization remains controversial. Recently some authors have advocated the use of morphologic and postcontrast features for this purpose. Quantitative breast MRI techniques have not been applied extensively in breast diseases. Magnetization transfer (MT) is a quantitative MR technique commonly used to investigate neurological diseases. In breast diseases the use of MT has been limited to improving visualization of areas of enhancement in postcontrast images. The purpose of this study was to evaluate the feasibility and utility of MT in discriminating benign from malignant breast lesions. Fifty-two lesions, Bl-RADS 4 and 5, from 49 patients, were prospectively evaluated using the MT ratio (MTR). Patients were divided into two groups: benign and malignant lesions. The MTR of fat, pectoralis major muscle, fibroglandular tissue, and breast lesions were calculated. A statistically significant difference was found between MTR from benign and malignant lesions (P < 0.001). Preliminary results suggest that MT can be used to evaluate breast lesions. Further studies are necessary to better define the utility and applicability of this technique.

STIR, SPIR and SPAIR techniques in magnetic resonance of the breast: a comparative study

The amount of fat is a component that complicates the clinical evaluation and the differential diagnostic between benign and malign lesions in the breast MRI examinations. To overcome this problem, an effective erasing of the fat signal over the images acquisition process, is essentials. This study aims to compare three fat suppression techniques (STIR, SPIR, SPAIR) in the MR images of the breast and to evaluate the best image quality regarding its clinical usefulness. To mimic breast women, a breast phantom was constructed. First the exterior contour and, in second time, its content which was selected based on 7 samples with different components. Finally it was undergone to a MRI breast protocol with the three different fat saturation techniques. The examinations were performed on a 1.5 T MRI system (Philips®). A group of 5 experts evaluated 9 sequences, 3 of each with fat suppression techniques, in which the frequency offset and TI (Inversion Time) were the variables changed. This qualitative image analysis was performed according 4 parameters (saturation uniformity, saturation efficacy, detail of the anatomical structures and differentiation between the fibroglandular and adipose tissue), using a five-point Likert scale. The statistics analysis showed that anyone of the fat suppression techniques demonstrated significant differences compared to the others with (p > 0.05) and regarding each parameter independently. By Fleiss’ kappa coefficient there was a good agreement among observers P(e) = 0.68. When comparing STIR, SPIR and SPAIR techniques it was confirmed that all of them have advantages in the study of the breast MRI. For the studied parameters, the results through the Friedman Test showed that there are similar advantages applying anyone of these techniques.

Contrast enhanced breast ultrasound to differentiate papillomas from intraductal secretion : initial experience : P22

Purpose: To describe low mechanical index grey scale contrast enhanced breast ultrasound in patients with intraductal echogenic material in the differentiation of papillomas from intraductal secretions. Methods and materials: In five patients with echographically detected ductal dilatation containing echogenic material low mechanical index grey scale contrast enhanced ultrasonography was performed. No patient had nipple discharge. The examination was performed with a 9 MHz linear transducer after injection of 4 ml of Sonovue. It was assessed if contrast enhancement was present or not. The results were correlated with histologic results after surgical resection or percutaneous biopsy when performed. Results: In 3 patients contrast enhancement was observed. These patients were operated and the papillomas confirmed by histology. In two patients no contrast enhancement was observed. In one of these two patients percutaneous biopsy was performed without evidence of a papillary lesion. The second patient presented with multiple dilated ducts containing echogenic material. No biopsy was performed but breast MRI showed no intraductal enhancement supporting the non papillary nature of the intraductal material. Conclusion: This pilot study shows that contrast enhanced ultrasound is able to detect the vascularisation of papillomas and that it may differentiate intraductal papillomas from secretions.

Comparison of gadoteric acid and gadobutrol for detection as well as morphologic and dynamic characterization of lesions on breast dynamic contrast-enhanced magnetic resonance imaging

OBJECTIVE In contrast to conventional breast imaging techniques, one major diagnostic benefit of breast magnetic resonance imaging (MRI) is the simultaneous acquisition of morphologic and dynamic enhancement characteristics, which are based on angiogenesis and therefore provide insights into tumor pathophysiology. The aim of this investigation was to intraindividually compare 2 macrocyclic MRI contrast agents, with low risk for nephrogenic systemic fibrosis, in the morphologic and dynamic characterization of histologically verified mass breast lesions, analyzed by blinded human evaluation and a fully automatic computer-assisted diagnosis (CAD) technique. MATERIALS AND METHODS Institutional review board approval and patient informed consent were obtained. In this prospective, single-center study, 45 women with 51 histopathologically verified (41 malignant, 10 benign) mass lesions underwent 2 identical examinations at 1.5 T (mean time interval, 2.1 days) with 0.1-mmol kg doses of gadoteric acid and gadobutrol. All magnetic resonance images were visually evaluated by 2 experienced, blinded breast radiologists in consensus and by an automatic CAD system, whereas the morphologic and dynamic characterization as well as the final human classification of lesions were performed based on the categories of the Breast imaging reporting and data system MRI atlas. Lesions were also classified by defining their probability of malignancy (morpho-dynamic index; 0%-100%) by the CAD system. Imaging results were correlated with histopathology as gold standard. RESULTS The CAD system coded 49 of 51 lesions with gadoteric acid and gadobutrol (detection rate, 96.1%); initial signal increase was significantly higher for gadobutrol than for gadoteric acid for all and the malignant coded lesions (P < 0.05). Gadoteric acid resulted in more postinitial washout curves and fewer continuous increases of all and the malignant lesions compared with gadobutrol (CAD hot spot regions, P < 0.05). Morphologically, the margins of the malignancies were different between the 2 agents, whereas gadobutrol demonstrated more spiculated and fewer smooth margins (P < 0.05). Lesion classifications by the human observers and by the morpho-dynamic index compared with the histopathologic results did not significantly differ between gadoteric acid and gadobutrol. CONCLUSIONS Macrocyclic contrast media can be reliably used for breast dynamic contrast-enhanced MRI. However, gadoteric acid and gadobutrol differed in some dynamic and morphologic characterization of histologically verified breast lesions in an intraindividual, comparison. Besides the standardization of technical parameters and imaging evaluation of breast MRI, the standardization of the applied contrast medium seems to be important to receive best comparable MRI interpretation.

Simultaneous multi-slice readout-segmented echo planar imaging for accelerated diffusion-weighted imaging of the breast

OBJECTIVES Readout-segmented echo planar imaging (rs-EPI) significantly reduces susceptibility artifacts in diffusion-weighted imaging (DWI) of the breast compared to single-shot EPI but is limited by longer scan times. To compensate for this, we tested a new simultaneous multi-slice (SMS) acquisition for accelerated rs-EPI. MATERIALS AND METHODS After approval by the local ethics committee, eight healthy female volunteers (age, 38.9±13.1 years) underwent breast MRI at 3T. Conventional as well as two-fold (2× SMS) and three-fold (3× SMS) slice-accelerated rs-EPI sequences were acquired at b-values of 50 and 800s/mm(2). Two independent readers analyzed the apparent diffusion coefficient (ADC) in fibroglandular breast parenchyma. The signal-to-noise ratio (SNR) was estimated based on the subtraction method. ADC and SNR were compared between sequences by using the Friedman test. RESULTS The acquisition time was 4:21min for conventional rs-EPI, 2:35min for 2× SMS rs-EPI and 1:44min for 3× SMS rs-EPI. ADC values were similar in all sequences (mean values 1.62×10(-3)mm(2)/s, p=0.99). Mean SNR was 27.7-29.6, and no significant differences were found among the sequences (p=0.83). CONCLUSION SMS rs-EPI yields similar ADC values and SNR compared to conventional rs-EPI at markedly reduced scan time. Thus, SMS excitation increases the clinical applicability of rs-EPI for DWI of the breast.

Cost-effectiveness of screening with contrast enhanced magnetic resonance imaging vs X-ray mammography of women at a high familial risk of breast cancer

Contrast enhanced magnetic resonance imaging (CE MRI) is the most sensitive tool for screening women who are at high familial risk of breast cancer. Our aim in this study was to assess the cost-effectiveness of X-ray mammography (XRM), CE MRI or both strategies combined. In total, 649 women were enrolled in the MARIBS study and screened with both CE MRI and mammography resulting in 1881 screens and 1-7 individual annual screening events. Women aged 35-49 years at high risk of breast cancer, either because they have a strong family history of breast cancer or are tested carriers of a BRCA1, BRCA2 or TP53 mutation or are at a 50% risk of having inherited such a mutation, were recruited from 22 centres and offered annual MRI and XRM for between 2 and 7 years. Information on the number and type of further investigations was collected and specifically calculated unit costs were used to calculate the incremental cost per cancer detected. The numbers of cancer detected was 13 for mammography, 27 for CE MRI and 33 for mammography and CE MRI combined. In the subgroup of BRCA1 (BRCA2) mutation carriers or of women having a first degree relative with a mutation in BRCA1 (BRCA2) corresponding numbers were 3 (6), 12 (7) and 12 (11), respectively. For all women, the incremental cost per cancer detected with CE MRI and mammography combined was 28 pound 284 compared to mammography. When only BRCA1 or the BRCA2 groups were considered, this cost would be reduced to 11 pound 731 (CE MRI vs mammography) and 15 pound 302 (CE MRI and mammography vs mammography). Results were most sensitive to the unit cost estimate for a CE MRI screening test. Contrast-enhanced MRI might be a cost-effective screening modality for women at high risk, particularly for the BRCA1 and BRCA2 subgroups. Further work is needed to assess the impact of screening on mortality and health-related quality of life.

Quantificação da difusão na ressonância magnética da mama: ADC e Kurtosis

Mestrado em Radiações Aplicadas às Tecnologias da Saúde. Área de especialização: Ressonância Magnética

DWI: factores que influenciam a medição do coeficiente de difusão aparente (ADC) no estudo da mama

Mestrado em Radiações Aplicadas às Tecnologias da Saúde. Área de especialização: Ressonância Magnética

Difusão molecular em ressonância magnética para estudo de lesões mamárias malignas

Objetivos – Com este estudo pretendeu-se i) avaliar o contributo da aplicação da sequência de difusão na caracterização das lesões mamárias malignas; ii) considerar se a sequência de difusão deve incorporar o protocolo standard em RM mamária e iii) correlacionar os resultados dos valores de coeficiente aparente de difusão (ADC) e os resultados histológicos. Metodologia – A amostra incluiu 18 pacientes do sexo feminino, com idades compreendidas entre 38 e 71 anos, que apresentavam lesões mamárias malignas confirmadas histologicamente. Foi adicionado ao protocolo de RM mamária a sequência de difusão, de modo a calcular os valores de ADC das lesões observadas. Resultados – Verificou-se que a range de valores de ADC para lesões malignas em ROI’s calculados no centro da lesão apresentavam uma média e desvio-padrão de (0,89 ± 0,14x10-3mm2/s). O método da utilização dos valores de ADC na caracterização de lesões mamárias malignas demonstrou uma sensibilidade de 100%. Conclusões – Neste estudo, com uma sensibilidade de 100%, a ponderação em difusão demonstrou ser uma técnica vantajosa na caracterização de lesões mamárias malignas pelo que se sugere a sua introdução no protocolo standard da RM mamária. ABSTRACT - Aims – The aim of this study was i) to evaluate the potential of the DWI sequence in the characterization of malignant breast lesions; ii) to verify if this sequence should incorporate the breast MRI protocol and iii) to correlate the apparent diffusion coefficients (ADC) values and histological results. Methodology – The sample includes 18 female patients between the ages of 38 and 71 years, who presented with malignant breast lesion confirmed by histology. The DWI sequence was added to the MRI standard protocol to calculate the ADC values. Results – In the results obtained we observed that the range of the ADC values calculated in the center of the malignant lesions, showed a mean and standard deviation of 0.89 ± 0.14 x10-3 mm2 / s. This method of using the ADC values for the detection of malignant lesions showed a sensitivity of 100%. Conclusion – The DWI technique proved to be a useful method in the characterization of malignant breast lesions, as it showed a sensitivity of 100%, so we suggest its inclusion in the Breast MR standard protocol.

Análise quantitativa da saturação de gordura em ressonância magnética mamária: comparação das técnicas SPAIR e DIXON

Introdução – A ressonância magnética (RM) mamária com injeção de contraste é uma ferramenta indispensável para a caracterização de lesões mamárias. Para tal, é fulcral uma boa capacidade de saturação de gordura de forma a delimitar as lesões observadas. Este trabalho tem como objetivo analisar quantitativa e qualitativamente as técnicas de saturação de gordura em RM mamária, nomeadamente as técnicas SPAIR e Dixon. Metodologia – Utilizou-se um equipamento de RM de 1,5T com bobina específica para a mama. Aplicou-se, durante o exame, uma sequência adicional em que a técnica de saturação de gordura utilizada foi a Dixon. Posteriormente foram analisadas as imagens obtidas com as técnicas SPAIR e Dixon e colocadas regiões de interesse (ROI) na lesão, na glândula mamária, no tecido adiposo e no ar. Estes valores de sinal obtidos foram registados e calcularam-se as relações sinal-ruído (SNR), contraste-ruído (CNR) e uniformidade de saturação de gordura para as mesmas estruturas a analisar e nas distintas sequências. Resultados – Verificou-se que a técnica de supressão de gordura Dixon apresenta resultados quantitativos e qualitativos superiores à técnica SPAIR. Conclusões – Recomenda-se a utilização da técnica Dixon para saturação de gordura nas sequências de estudo dinâmico com agente de contraste, especificamente nos estudos de RM mamária.