Functional ultrasound imaging reveals different odor-evoked patterns of vascular activity in the main olfactory bulb and the anterior piriform cortex.

Topographic representation of the outside world is a key feature of sensory systems, but so far it has been difficult to define how the activity pattern of the olfactory information is distributed at successive stages in the olfactory system. We studied odor-evoked activation patterns in the main olfactory bulb and the anterior piriform cortex of rats using functional ultrasound (fUS) imaging. fUS imaging is based on the use of ultrafast ultrasound scanners and detects variations in the local blood volume during brain activation. It makes deep brain imaging of ventral structures, such as the piriform cortex, possible. Stimulation with two different odors (hexanal and pentylacetate) induced the activation of odor-specific zones that were spatially segregated in the main olfactory bulb. Interestingly, the same odorants triggered the activation of the entire anterior piriform cortex, in all layers, with no distinguishable odor-specific areas detected in the power Doppler images. These fUS imaging results confirm the spatial distribution of odor-evoked activity in the main olfactory bulb, and furthermore, they reveal the absence of such a distribution in the anterior piriform cortex at the macroscopic scale in vivo.

Non-invasive transcranial ultrasound therapy based on a 3D CT scan: protocol validation and in vitro results.

A non-invasive protocol for transcranial brain tissue ablation with ultrasound is studied and validated in vitro. The skull induces strong aberrations both in phase and in amplitude, resulting in a severe degradation of the beam shape. Adaptive corrections of the distortions induced by the skull bone are performed using a previous 3D computational tomography scan acquisition (CT) of the skull bone structure. These CT scan data are used as entry parameters in a FDTD (finite differences time domain) simulation of the full wave propagation equation. A numerical computation is used to deduce the impulse response relating the targeted location and the ultrasound therapeutic array, thus providing a virtual time-reversal mirror. This impulse response is then time-reversed and transmitted experimentally by a therapeutic array positioned exactly in the same referential frame as the one used during CT scan acquisitions. In vitro experiments are conducted on monkey and human skull specimens using an array of 300 transmit elements working at a central frequency of 1 MHz. These experiments show a precise refocusing of the ultrasonic beam at the targeted location with a positioning error lower than 0.7 mm. The complete validation of this transcranial adaptive focusing procedure paves the way to in vivo animal and human transcranial HIFU investigations.

[Ultrasonic arrays: new therapeutic developments]. / Réseaux de transducteurs ultrasonores: nouvelles avancées thérapeutiques.

Bursts of focused ultrasound energy a billion times more intense than diagnostic ultrasound have become a non-invasive option for tumor ablation, from prostate cancer to uterine fibroid, during the last decade. Despite this progress, many issues still need to be addressed. First, for brain targeting, the correction of distortions induced by the skull remains today a technological achievement that still needs to be validated clinically. Secondly, the problem of motion artifacts for abdominal treatments becomes today an important research topic. For all these issues, the potential of new ultrasonic therapy devices able to work both in Transmit and Receive modes will be emphasized and clinical results on monkeys and pigs will be presented.

High power phased array prototype for clinical high intensity focused ultrasound : applications to transcostal and transcranial therapy.

Bursts of focused ultrasound energy three orders of magnitude more intense than diagnostic ultrasound became during the last decade a noninvasive option for treating cancer from breast to prostate or uterine fibroid. However, many challenges remain to be addressed. First, the corrections of distortions induced on the ultrasonic therapy beam during its propagation through defocusing obstacles like skull bone or ribs remain today a technological performance that still need to be validated clinically. Secondly, the problem of motion artifacts particularly important for the treatment of abdominal parts becomes today an important research topic. Finally, the problem of the treatment monitoring is a wide subject of interest in the growing HIFU community. For all these issues, the potential of new ultrasonic therapy devices able to work both in Transmit and Receive modes will be emphasized. A review of the work under achievement at L.O.A. using this new generation of HIFU prototypes on the monitoring, motion correction and aberrations corrections will be presented.

Compensating for bone interfaces and respiratory motion in high-intensity focused ultrasound.

Bursts of focused ultrasound energy a thousand times more intense than diagnostic ultrasound have become a non-invasive option for treating cancer, from breast to prostate or uterine fibroid, during the last decade. Despite this progress, many issues still need to be addressed. First, the distortions caused by defocusing obstacles, such as the skull or ribs, on the ultrasonic therapeutic beam are still being investigated. Multi-element transducer technology must be used in order to achieve such transcranial or transcostal adaptive focusing. Second, the problem of motion artifacts, a key component in the treatment of abdominal lesions, has been shown significantly to influence the efficacy and treatment time. Though many methods have been proposed for the detection of organ motion, little work has been done to develop a comprehensive solution including motion tracking and feedback correction in real time. This paper is a review of the work achieved by authors in transcranial high-intensity focused ultrasound (HIFU), transcostal HIFU and motion compensated HIFU. For these three issues, the optimal solution can be reached using the same technology of multi-element transducers devices able to work both in transmit and receive modes.

Time reversal of electromagnetic waves.

We report the first experimental demonstration of time-reversal focusing with electromagnetic waves. An antenna transmits a 1-micros electromagnetic pulse at a central frequency of 2.45 GHz in a high-Q cavity. Another antenna records the strongly reverberated signal. The time-reversed wave is built and transmitted back by the same antenna acting now as a time-reversal mirror. The wave is found to converge to its initial source and is compressed in time. The quality of focusing is determined by the frequency bandwidth and the spectral correlations of the field within the cavity.

[Imported myiasis: 7 cases of cutaneous parasitism caused by Dermatobia hominis flie larvas]. / Miasis importada: siete casos de parasitación cutánea por larvas de la mosca Dermatobia hominis.

Myiasis is the parasitism of organs and tissues of warm-blooded vertebrates by flies larvae. D hominis is a flie geographically restricted to tropical America from Mexico to northern Argentina. The adult flie, which is not hematophagous, needs to put its eggs on the abdominal surface of hematophagous arthropods which serve as carriers of future larvae which are deposited on the skin of the hosts (mammals, birds and accidentally men) when biting. Seven patients (two females) aged 7 to 35 years old, of different nationalities, recalled receiving mosquito bites, after staying in tropical American areas in the previous forty days. They presented furuncle-like lesions in exposed surfaces of the body. These lesions, 2-3 cm long, pruritic and mildly tender, broke and released a serous or serohematic fluid. Through the resulting opening, it was possible to partially observe the larva. Larvae were extracted by manual pressure (4) or surgical incision (3) and identified as D hominis larvae. Diagnosis of dermatobiasis, an imported myiasis, must be based on the characteristics of lesions and the previous residence in endemic areas of America.

Community- and hospital-acquired respiratory syncytial virus infections in Chile.

Nasopharyngeal aspirates were obtained on admission from 614 patients younger than 2 years of age who were hospitalized in a ward for acute respiratory infections from June 1988 through October, 1989, in Santiago, Chile. Patients in two rooms were followed during the cold seasons by sampling aspirates every other day during the child's entire hospital stay. Clinical features were recorded daily. Indirect monoclonal immunofluorescent assay and isolation in HEp-2 were used for respiratory syncytial virus (RSV) diagnosis. The mean RSV detection rate was 39% at the time of admission, ranging from 8% in April, 1989, to 62% in July, 1988. During the cold months 43 of 288 (15%) nosocomial RSV cases were detected. Pneumonia and wheezing bronchitis were the principal diagnoses of both groups admitted, whether they were shedding RSV or not. It is concluded that RSV plays a major role in admissions for acute respiratory infections, as well as in nosocomial infections, in Santiago. Because clinical features do not allow one to differentiate viral from bacterial acute respiratory infections, the importance of rapid viral diagnosis is emphasized.

[Diagnosis of sexually transmitted diseases in Chilean pregnant adolescents]. / Diagnóstico de enfermedades de transmisión sexual en adolescentes embarazadas chilenas.

We searched in 100 healthy pregnant women by isolation, the presence of Neisseria gonorrhoeae, Herpes simplex, Mycoplasma hominis, Ureaplasma urealyticum and Chlamydia trachomatis. Blood was also taken for examination of specific antibodies to these microorganisms. We studied only for antibodies titled Cytomegalovirus (CMV), Treponema pallidum and Human Immunodeficiency Virus, and Condyloma acuminatum by cervical cytology. In 85 adolescents we found 5 (6%) patients with C. trachomatis, four of these patients had another microorganism added, one with N. gonorrhoeae, M. hominis and U. Urealyticum, one with U. urealyticum and the last two with M. hominis and U. urealyticum, In relation to Mycoplasmas 69 (81%) out of 85 had Mycoplasmas, 4 (5%) had M. hominis, 46 (54%) U. urealyticum and 19 (22%) patients had both. The seropositivity to CMV was 96.25%. We didn't find any other microorganism. We concluded that the rate of STD in chilean pregnant adolescent women is high, especially with no traditional bacteria.

Diagnóstico de enfermedades de transmisión sexual en adolescentes embarazadas chilenas / Diagnosis of sexually transmitted diseases in Chilean pregnant adolescents

En 100 adolescentes embarazadas buscamos por cultivo la presencia de Neisseria gnorrhoeae, Herpes simplex, Mycoplasmas hominis, Ureoplasma urealyticum y Chlamydia trachomatis y los títulos de anticuerpos correspondientes. Buscamos sólo por tasas de anticuerpos a Citomegalovirus (CMV), Treponema pallidum y el Virus de la Inmunodeficiencia Humana (VIH), Condiloma acuminado fue investigado por citología cervical. En 85 adolescentes encontramos 5 (6%) pacientes con C. trachomatis, cuatro de estas pacientes presentaban además otros microorganismos, una con N. gonorrhoeae, M. hominis y U. urealyticum, una con U. urealyticum y las dos últimas con M. hominis y U. urealyticum. En relación a los Mycoplasmas 69 (81%) de 85 tuvo Mycoplasmas, 4 (5%) M. hominis, 46 (54%) U. Urealyticum y las dos últimas con M. hominis y U. urealyticum. En relación a los Mycoplasmas 69 (81%) de 85 tuvo Mycoplasmas, 4 (5%) M. hominis, 46 (54%) U. urealyticum y 19 (22%) pacientes presentaron ambos. La seropositividad para Citomegalovirus (CMV) fue 96,25%. No encontramos los otros microorganismos buscados. Se concluye que la frecuencia de enfermedades de transmisión sexual en adolescentes chilenas es alta, especialmente por gérmenes no tradicionales