A. Tardivon

Quantitative Assessment of Breast Lesion Viscoelasticity: Initial Clinical Results Using Supersonic Shear Imaging

This paper presents an initial clinical evaluation of in vivo elastography for breast lesion imaging using the concept of supersonic shear imaging. This technique is based on the combination of a radiation force induced in tissue by an ultrasonic beam and an ultrafast imaging sequence capable of catching in real time the propagation of the resulting shear waves. The local shear wave velocity is recovered using a time-offlight technique and enables the 2-D mapping of shear elasticity. This imaging modality is implemented on a conventional linear probe driven by a dedicated ultrafast echographic device. Consequently, it can be performed during a standard echographic examination. The clinical investigation was performed on 15 patients, which corresponded to 15 lesions (4 cases BI-RADS 3, 7 cases BI-RADS 4 and 4 cases BI-RADS 5). The ability of the supersonic shear imaging technique to provide a quantitative and local estimation of the shear modulus of abnormalities with a millimetric resolution is illustrated on several malignant (invasive ductal and lobular carcinoma) and benign cases (fibrocystic changes and viscous cysts). In the investigated cases, malignant lesions were found to be significantly different from benign solid lesions with respect to their elasticity values. Cystic lesions have shown no shear wave propagate at all in the lesion (because shear waves do not propage in liquid). These preliminary clinical results directly demonstrate the clinical feasibility of this new elastography technique in providing quantitative assessment of relative stiffness of breast tissues. This technique of evaluating tissue elasticity gives valuable information that is complementary to the B-mode morphologic information. More extensive studies are necessary to validate the assumption that this new mode potentially helps the physician in both false-positive and false-negative rejection.

Shear-wave Elastography Improves the Specificity of Breast US: The BE1 Multinational Study of 939 Masses

PURPOSE To determine whether adding shear-wave (SW) elastographic features could improve accuracy of ultrasonographic (US) assessment of breast masses. MATERIALS AND METHODS From September 2008 to September 2010, 958 women consented to repeat standard breast US supplemented by quantitative SW elastographic examination in this prospective multicenter institutional review board-approved, HIPAA-compliant protocol. B-mode Breast Imaging Reporting and Data System (BI-RADS) features and assessments were recorded. SW elastographic evaluation (mean, maximum, and minimum elasticity of stiffest portion of mass and surrounding tissue; lesion-to-fat elasticity ratio; ratio of SW elastographic-to-B-mode lesion diameter or area; SW elastographic lesion shape and homogeneity) was performed. Qualitative color SW elastographic stiffness was assessed independently. Nine hundred thirty-nine masses were analyzable; 102 BI-RADS category 2 masses were assumed to be benign; reference standard was available for 837 category 3 or higher lesions. Considering BI-RADS category 4a or higher as test positive for malignancy, effect of SW elastographic features on area under the receiver operating characteristic curve (AUC), sensitivity, and specificity after reclassifying category 3 and 4a masses was determined. RESULTS Median participant age was 50 years; 289 of 939 (30.8%) masses were malignant (median mass size, 12 mm). B-mode BI-RADS AUC was 0.950; eight of 303 (2.6%) BI-RADS category 3 masses, 18 of 193 (9.3%) category 4a lesions, 41 of 97 (42%) category 4b lesions, 42 of 57 (74%) category 4c lesions, and 180 of 187 (96.3%) category 5 lesions were malignant. By using visual color stiffness to selectively upgrade category 3 and lack of stiffness to downgrade category 4a masses, specificity improved from 61.1% (397 of 650) to 78.5% (510 of 650) (P<.001); AUC increased to 0.962 (P=.005). Oval shape on SW elastographic images and quantitative maximum elasticity of 80 kPa (5.2 m/sec) or less improved specificity (69.4% [451 of 650] and 77.4% [503 of 650], P<.001 for both), without significant improvement in sensitivity or AUC. CONCLUSION Adding SW elastographic features to BI-RADS feature analysis improved specificity of breast US mass assessment without loss of sensitivity.

Breast lesions: quantitative elastography with supersonic shear imaging--preliminary results.

PURPOSE To determine the appearance of breast lesions at quantitative ultrasonographic (US) elastography by using supersonic shear imaging (SSI) and to assess the correlation between quantitative values of lesion stiffness and pathologic results, which were used as the reference standard. MATERIALS AND METHODS This study was approved by the French National Committee for the Protection of Patients Participating in Biomedical Research Programs. All patients provided written informed consent. Conventional US and SSI quantitative elastography were performed in 46 women (mean age, 57.6 years; age range, 38-71 years) with 48 breast lesions (28 benign, 20 malignant; mean size, 14.7 mm); pathologic results were available in all cases. Quantitative lesion elasticity was measured in terms of the Young modulus (in kilopascals). Sensitivity, specificity, and area under the curve were obtained by using a receiver operating characteristic curve analysis to assess diagnostic performance. RESULTS All breast lesions were detected at SSI. Malignant lesions exhibited a mean elasticity value of 146.6 kPa +/- 40.05 (standard deviation), whereas benign ones had an elasticity value of 45.3 kPa +/- 41.1 (P < .001). Complicated cysts were differentiated from solid lesions because they had elasticity values of 0 kPa (no signal was retrieved from liquid areas). CONCLUSION SSI provides quantitative elasticity measurements, thus adding complementary information that potentially could help in breast lesion characterization with B-mode US.

Dual-energy contrast-enhanced digital mammography: initial clinical results of a multireader, multicase study

IntroductionThe purpose of this study was to compare the diagnostic accuracy of dual-energy contrast-enhanced digital mammography (CEDM) as an adjunct to mammography (MX) ± ultrasonography (US) with the diagnostic accuracy of MX ± US alone.MethodsOne hundred ten consenting women with 148 breast lesions (84 malignant, 64 benign) underwent two-view dual-energy CEDM in addition to MX and US using a specially modified digital mammography system (Senographe DS, GE Healthcare). Reference standard was histology for 138 lesions and follow-up for 12 lesions. Six radiologists from 4 institutions interpreted the images using high-resolution softcopy workstations. Confidence of presence (5-point scale), probability of cancer (7-point scale), and BI-RADS scores were evaluated for each finding. Sensitivity, specificity and ROC curve areas were estimated for each reader and overall. Visibility of findings on MX ± CEDM and MX ± US was evaluated with a Likert scale.ResultsThe average per-lesion sensitivity across all readers was significantly higher for MX ± US ± CEDM than for MX ± US (0.78 vs. 0.71 using BIRADS, p = 0.006). All readers improved their clinical performance and the average area under the ROC curve was significantly superior for MX ± US ± CEDM than for MX ± US ((0.87 vs 0.83, p = 0.045). Finding visibility was similar or better on MX ± CEDM than MX ± US in 80% of cases.ConclusionsDual-energy contrast-enhanced digital mammography as an adjunct to MX ± US improves diagnostic accuracy compared to MX ± US alone. Addition of iodinated contrast agent to MX facilitates the visualization of breast lesions.

Élastosonographie du sein : étude prospective de 122 lésions

Resume Objectif Evaluer l’elastosonographie dans la caracterisation des nodules mammaires Materiel et methodes L’elastosonographie (appareil Hitachi, sonde de 7,5-13 Mhz, classification de Ueno, scores 1-3 = benin et 4-5 = malin) a ete evaluee dans 125 lesions infra-cliniques chez 114 patientes. Les resultats ont ete compares a ceux des categories BI-RADS-echographie de l’ACR (benin = 2 et 3, malin = 4 et 5) et aux resultats des prelevements percutanes et/ou de la chirurgie (122 lesions evaluees, 59 % Resultats Il y a eu 3 echecs de la technique (2,4 %). L’elastographie etait concordante avec l’histologie pour 101 lesions, avec 13 faux negatifs et 8 faux positifs (sensibilite : 78,7 %, specificite : 86,9 %, VPP : 85,7 %, VPN : 80,3 %) ; versus pour la classification BI-RADS une concordance pour 98 lesions avec 1 faux negatif et 23 faux positifs (sensibilite : 98,4 %, specificite : 47,5 %, VPP : 65,2 %, VPN : 96,7 %). Conclusion L’elastographie est une methode complementaire simple et rapide permettant d’augmenter la specificite et la VPP de l’imagerie morphologique dans les nodules peu suspects (categories BI-RADS 3 et 4a) ce qui devrait diminuer le taux de prelevements benins inutiles.

Monitoring therapeutic efficacy in breast carcinomas

The aim of imaging during and after neoadjuvant therapy is to document and quantify tumor response: has the tumor size been accurately measured? Certainly, the most exciting information for the oncologists is: can we identify good or nonresponders, and can we predict the pathological response early after the initiation of treatment? This review article will discuss the role and the performance of the different imaging modalities (mammography, ultrasound, magnetic resonance imaging and FDG-PET imaging) for evaluating this therapeutic response. It is important to emphasize that, at this time, clinical examination and conventional imaging (mammography and ultrasound) are the only methods recognized by the international criteria. Magnetic resonance imaging and FDG-PET imaging are very promising for predicting the response early after the initiation of neoadjuvant chemotherapy.

How to optimize breast ultrasound

Breast cancer is the most common female cancer, and the second cause of cancer-related mortality of women in our society. Mammography is the gold-standard method of breast imaging. However it is not an optimal screening tool, especially in cases of dense breast parenchyma. Even when optimally performed, its sensitivity ranges between 69 and 90%. Ultrasound represents an additional diagnostic tool that raises the detection rate of benign and malignant breast lesions. It is the method of choice for differentiating solid from cystic lesions, for further characterizing mammographic findings and better appreciating palpable breast lesions. B-mode ultrasonography is used in every day practice. Harmonic imaging and compound imaging can be used to ameliorate the image contrast and resolution. Colour Doppler is used for studying lesion vascularization however there is no consensus as to whether it really permits to differentiate malignancies from benign lesions. New technical developments such as breast elastography, 3D ultrasound and dedicated ultrasound computed aided diagnosis (CAD) are promising methods for the future.

Nonlinear viscoelastic properties of tissue assessed by ultrasound

A technique to assess qualitatively the presence of higher-order viscoelastic parameters is presented. Low-frequency, monochromatic elastic waves are emitted into the material via an external vibrator. The resulting steady-state motion is detected in real time via an ultra fast ultrasound system using classical, one-dimensional (1-D) ultrasound speckle correlation for motion estimation. Total data acquisition lasts only for about 250 ms. The spectrum of the temporal displacement data at each image point is used for analysis. The presence of nonlinear effects is detected by inspection of the ratio of the second harmonics amplitude with respect to the total amplitude summed up to the second harmonic. Results from a polyacrylamide-based phantom indicate a linear response (i.e., the absence of higher harmonics) for this type of material at 65 Hz mechanical vibration frequency and about 100 mum amplitude. A lesion, artificially created by injection of glutaraldehyde into a beef specimen, shows the development of higher harmonics at the location of injection as a function of time. The presence of upper harmonics is clearly evident at the location of a malignant lesion within a mastectomy

Contrast enhanced spectral mammography: better than MRI?

The initial method developed for contrast enhanced mammography used temporal acquisitions of high-energy images before and after intravenous injection of iodinated contrast medium [1–4]. The patient had to be primarily positioned for breast compression, using minimal pressure not to alter diffusion of contrast agent. A baseline image (mask) was obtained before injection. Following contrast administration, serial images were acquired over several minutes. Logarithmic subtraction of pre and post-contrast images was applied. Initial experience with such dynamic imaging showed the clinical feasibility of the technique. Further work investigated the diagnostic benefits offered by this modality over conventional mammography, showing a gain in sensitivity for the detection of cancer particularly in dense breasts [4]. The technique, however, proved sensitive to motion artifacts. It also posed the issue of the additional radiation exposure applied for an examination limited to one breast at a time in a single projection view. The second method developed for contrast enhanced mammography was based on dual energy acquisition. Physical and clinical research currently focuses on this technology also referred to as spectral imaging or contrast enhanced spectral mammography (CESM). To allow visualization of low concentration of iodine with only a modest increase in radiation exposure, the x-ray spectrum delivers energies just above the K-edge of iodine (33.2 keV) while using a high voltage range of 45–50kVp [5]. In that setting the patient receives contrast administration first and then is positioned for mammography with normal compression of the breast. A typical protocol goes from obtaining the mediolateral oblique (MLO) view on one breast – typically 2 min after the start of injection – to the MLO view on the other breast, then from the craniocaudal (CC) view on the first side – 4 min after the start of injection – to the CC view on the other side. For each view, a pair of low and highenergy images is acquired. The two images are combined so that the areas of iodine enhancement are highlighted from background parenchyma. Two views of both breasts can be obtained after a single injection of contrast medium.

Digital breast tomosynthesis versus mammography and breast ultrasound: a multireader performance study.

AbstractObjectivesTo compare the diagnostic performance of single-view breast tomosynthesis (BT) with that of dual-view mammography (MX); to assess the benefit of adding the craniocaudal (CC) mammographic view to BT, and of adding BT to MX plus breast ultrasound, considered to be the reference work-up.MethodsOne hundred and fifty-five consenting patients with unresolved mammographic and/or ultrasound findings or breast symptoms underwent conventional work-up plus mediolateral oblique-view BT of the affected breast. The final study set in 130 patients resulted in 55 malignant and 76 benign and normal cases. Seven breast radiologists rated the cases through five sequential techniques using a BIRADS-based scale: MX, MX + ultrasound, MX + ultrasound + BT, BT, BT + MX(CC). Multireader, multicase receiver operating characteristic (ROC) analysis was performed and performance of the techniques was assessed from the areas under ROC curves. The performance of BT and of BT + MX(CC) was tested versus MX; the performance of MX + ultrasound + BT tested versus MX + ultrasound.ResultsTomosynthesis was found to be non-inferior to mammography. BT + MX(CC) did not appear to be superior to MX, and MX + ultrasound + BT not superior to MX + ultrasound.ConclusionsOverall, none of the five techniques tested outperformed the others. Further clinical studies are needed to clarify the role of BT as a substitute for traditional work-up in the diagnostic environment.Key Points• Digital breast tomosynthesis is a new adjunct to mammography and breast ultrasound. • We compared the diagnostic performance of these investigations in an experimental observer study. • Single-view breast tomosynthesis was confirmed as non-inferior to dual-view mammography. • None of the investigations (or combinations) tested outperformed the others. • Further prospective studies are needed to clarify precise role of tomosynthesis for diagnostic application.