[Elastography of the breast: a prospective study of 122 lesions]

OBJECTIVE

To evaluate elastography in the characterization of breast nodules.

MATERIAL AND METHODS

Elastography (Hitachi, 7.5- to 13-MHz probe; Ueno classification, scores 1-3=benign, 4-5=malignant) was evaluated in 125 subclinical lesions in 114 patients. The results were compared to those of the ACR's BI-RADS sonography categories (benign=2 and 3, malignant=4 and 5) and to the results of the percutaneous samples taken and/or surgery (122 lesions evaluated, 59%<10 mm, 61 cancers, 61 benign lesions).

RESULTS

There were three technical failures (2.4%). The elastography was in agreement with histology for 101 lesions, with 13 false-negative results and eight false-positive results (sensitivity, 78.7%; specificity, 86.9%; PPV, 85.7%; NPV, 80.3%); versus agreement with the BI-RADS classification for 98 lesions with one false-negative result and 23 false-positive results (sensitivity, 98.4%; specificity, 47.5%; PPV, 65.2%; NPV, 96.7%).

CONCLUSION

Elastography is a simple and rapid complementary method that can improve the specificity and the PPV of morphological imaging studies of breast nodules with a low level of suspicion (BI-RADS categories 3 and 4a), which should decrease the rate of unnecessary benign biopsies.

Apport de l’IRM dans la maladie de Paget du sein

OBJECTIVE

Evaluate the usefulness of MRI in local staging of Paget disease of the breast.

MATERIALS AND METHODS

Clinical, radiological (mammographies, MRI), and histological data were analyzed in six female patients presenting Paget disease of the breast. The criteria for analysis in MRI were the following: morphology of the aureola-nipple plaque (thickening, regularity of the contour) and the type of enhancement after injection of contrast medium (signal intensity/time curve), detection of abnormal enhancing in the mammary gland, and ganglion areas.

RESULTS

None of the patients presented a palpable mass or a suspicious anomaly on mammography. On MRI, the aureola-nipple plaque was morphologically abnormal in four cases, with suspicious enhancement in two cases (two cases of ductal carcinoma in situ) and normal enhancement in two cases (one case of ductal carcinoma in situ). In the two other cases, the aureola-nipple plaque was normal (one case of ductal carcinoma in situ). Distant abnormal enhancement of the aureola-nipple plaque was noted in two cases (one case of ductal carcinoma in situ and one benign lesion).

CONCLUSION

The MRI aspect of the aureola-nipple plaque in Paget disease shows little concordance with the histological results. MRI can be useful in detecting distant lesions when there is no clinical sign nor a suspicious mammography.

Rotranslational state-to-state rates and spectral representation of inelastic collisions in low-temperature molecular hydrogen

Inelastic collisions in natural H2 are studied from the experimental and theoretical points of view between 10 and 140 K. Rotational populations and number densities measured by Raman spectroscopy along supersonic expansions of H2 provide the link between experimental and theoretical rotranslational state-to-state rate coefficients of H2 in the vibrational ground state. These rates are calculated in the close-scattering approach with the MOLSCAT code employing a recent ab initio H2-H2 potential. The calculated rates are assessed by means of a master equation describing the time evolution of the experimental rotational populations. The feasibility for obtaining the rates on the sole basis of the experiment is discussed. The dominant processes j(1)j(2)-->j'(1)j'(2) in the investigated thermal range are found to be 21-->01 >30-->12 >31-->11, proving the importance of double processes such as 30-->12. Good agreement is found between theory and experiment, as well as with earlier ultrasonic measurements of relaxation times. A spectral representation is proposed in order to visualize quantitatively the collisional contributions in any nonequilibrium time evolving process.

Efficient diode-pumped Yb3+:Y2SiO5 and Yb3+:Lu2SiO5 high-power femtosecond laser operation

We report the mode-locked operation of two new Yb-doped oxyorthosilicates, Y2SiO5 (YSO) and Lu2SiO5 (LSO), that are longitudinally diode pumped. Yb:YSO supplied pulses as short as 122 fs with 410 mW of output power at 1041 nm. More than 2.6 W of average output power, for pulse durations of 198 fs at 1044 nm and 260 fs at 1059 nm for Yb:YSO and Yb:LSO, respectively, were provided. These are, to our best knowledge, the highest values ever obtained and the most efficient mode-locked laser in such a classic fiber-coupled diode-pumping configuration.

Inelastic collisions in para-H2: translation-rotation state-to-state rate coefficients and cross sections at low temperature and energy

We report an experimental determination of the k(00-->02) rate coefficient for inelastic H(2):H(2) collisions in the temperature range from 2 to 110 K based on Raman spectroscopy data in supersonic expansions of para-H(2). For this purpose a more accurate method for inverting the master equation of rotational populations is presented. The procedure permits us to reduce the measured k(00-->02) rate coefficient to the corresponding sigma(00-->02) cross section in the range of precollisional energy from 360 to 600 cm(-1). Numerical calculations of sigma(00-->02) carried out in the frame of the coupled channel method are also reported for different intermolecular potentials of H(2). A good agreement is found between the experimental cross section and the numerical one derived from Diep and Johnson's potential [J. Chem. Phys. 112, 4465 (2000)].

Digital detectors for mammography: the technical challenges

This paper reviews the different techniques available and competing for full-field digital mammography. The detectors are described in their principles: photostimulable storage phosphor plates inserted as a cassette in a conventional mammography unit, dedicated active matrix detectors (i.e., flat-panel, thin-film transistor-based detectors) and scanning systems, using indirect and direct X-ray conversion. The main parameters that characterize the performances of the current systems and influence the quality of digital images are briefly explained: spatial resolution, detective quantum efficiency and modulation transfer function. Overall performances are often the result of compromises in the choice of technology.

Quoi de neuf en imagerie du sein ?

In 2004, breast cancer screening will be effective in France. This evolution has a strong impact on our mammographic practice that becomes a real mission of public health. Digital mammography, compared to screen-film mammography, provides the same results for the detection of breast cancer, computer-aided detection systems represent the most relevant application of this technology at this time. The setting up of a quality control will allow the introduction of this technology in screening during 2004. Percutaneous imaging-guided procedures are now currently used for the diagnosis of nonpalpable breast lesions and allow the selection of patients for surgery. These procedures have emphasized the need for a multidisciplinary approach of the patients. Indications of MRI have not changed because of its moderated specificity and no relevant development of interventional-guided procedures. Work on standardization of radiological reports and assessment categories goes on. This classification is already applied for mammography, and new classifications for lesions detected by ultrasound or MRI will be published by the American College of Radiology (Breast Imaging Reporting and Data System, 4th edition, available in 2003).

Experimental and theoretical study of line mixing in NH3 spectra. II. Effect of the perturber in infrared parallel bands

In a previous paper [J. Chem. Phys. 116, 7544 (2002) (Paper I)] a model, based on the energy corrected sudden approximation, was proposed for the construction of the line-mixing relaxation matrix. It was successfully tested by comparisons with measured infrared spectra of ammonia-helium mixtures. The present paper extends this preliminary study by considering mixtures of NH3 with H2 and Ar. Measurements have been made at room temperature in the regions of the nu2 and nu1 bands for pressures up to several hundred atmospheres. As in Paper I, the relaxation operator is constructed, within the impact approximation, using the ECS approximation. The data required are dynamical factors (which can be predicted from the NH3-X potential energy surface) and a scaling length (adjusted using line broadening data). Comparisons between measured and calculated absorptions demonstrate the quality of the model which satisfactory corrects for the large deviations with respect to the purely Lorentzian behavior. Line-mixing effects for NH3-Ar and NH3-H2 are qualitatively similar to those observed for NH3-He but quantitative differences exist, particularly when intra- and interbranch couplings are considered. Finally, the proposed model leads to very satisfactory results in the wings of both the purely rotational and nu2 bands of NH3 diluted in H2, opening promising perspectives for the remote sensing study of planetary atmospheres.

[Interventional radiology in nonpalpable lesions of the breast]

The increasing number of nonpalpable breast lesions found at screening mammography has induced the development of percutaneous imaging-guided procedures to reduce the number of surgical biopsies. After a description of the indications (classification of the American College of Radiology), the different types of sampling procedures (fine needle aspiration, core and large-core biopsies) will be described and the material used also. Depending on the type of breast lesions (mass, clustered microcalcifications), ultrasound--guided and stereotactic--guided biopsies will be explained. Clear information to the patients, efficient quality control and multidisciplinary approach are mandatory for the success of these percutaneous diagnostic procedures.