We designed, fabricated and tested the laser optoacoustic imaging system for breast cancer detection (LOIS-64), which fuses optical and acoustic imaging techniques in one modality by utilizing pulsed optical illumination and ultrawide-band ultrasonic detection of resulting optoacoustic (OA) signals. The system was designed to image a single breast slice in craniocaudal or mediolateral projection with an arc-shaped array of 64 ultrawide-band acoustic transducers. The system resolution on breast phantoms was at least 0.5 mm. The single-channel sensitivity of 1.66 mVPa was estimated to be sufficient for single-pulse imaging of 6 to 11 mm tumors through the whole imaging slice of the breast. The implemented signal processing using the wavelet transform allowed significant reduction of the low-frequency (LF) acoustic noise, allowed localization of the optoacoustic signals from tumors, and enhanced the contrast and sharpened the boundaries of the optoacoustic images of the tumors. During the preliminary clinical studies on 27 patients, the LOIS-64 was able to visualize 18 out of 20 malignant lesions suspected from mammography and ultrasound images and confirmed by the biopsy performed after the optoacoustic tomography (OAT) procedure.

Abstract. We develop a system for three-dimensional whole-body optoacoustic tomography of small animals for applications in preclinical research. The tomographic images are obtained while the objects of study ͑phantoms or mice͒ are rotated within a sphere outlined by a concave arc-shaped array of 64 piezocomposite transducers. Two pulsed lasers operating in the near-IR spectral range ͑755 and 1064 nm͒ with an average pulsed energy of about 100 mJ, a repetition rate of 10 Hz, and a pulse duration of 15 to 75 ns are used as optical illumination sources. During the scan, the mouse is illuminated orthogonally to the array with two wide beams of light from a bifurcated fiber bundle. The system is capable of generating images of individual organs and blood vessels through the entire body of a mouse with spatial resolution of ϳ0.5 mm.

Rotational spectroscopy and molecular structure of 1,1,2-trifluoroethylene and the 1,1,2-trifluoroethylenehydrogen fluoride complex Rotational spectroscopy and dipole moment of cis-cis HOONO and DOONO

We present a superfluid hydrodynamic model for the increase in moment of inertia, ∆I, of molecules rotating in liquid 4 He. The static inhomogeneous He density around each molecule (calculated using the Orsay-Paris liquid 4 He density functional) is assumed to adiabatically follow the rotation of the molecule. We find that the ∆I values created by the viscousless and irrotational flow are in good agreement with the observed increases for several molecules [OCS, (HCN) 2 , HCCCN, and HCCCH 3 ]. For HCN and HCCH, our model substantially overestimates ∆I. This is likely to result from a (partial) breakdown of the adiabatic following approximation.

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