Parallel-transmission-enabled magnetization-prepared rapid gradient-echo T1-weighted imaging of the human brain at 7 T.

One of the promises of Ultra High Field (UHF) MRI scanners is to bring finer spatial resolution in the human brain images due to an increased signal to noise ratio. However, at such field strengths, the spatial non-uniformity of the Radio Frequency (RF) transmit profiles challenges the applicability of most MRI sequences, where the signal and contrast levels strongly depend on the flip angle (FA) homogeneity. In particular, the MP-RAGE sequence, one of the most commonly employed 3D sequences to obtain T1-weighted anatomical images of the brain, is highly sensitive to these spatial variations. These cause deterioration in image quality and complicate subsequent image post-processing such as automated tissue segmentation at UHF. In this work, we evaluate the potential of parallel-transmission (pTx) to obtain high-quality MP-RAGE images of the human brain at 7 T. To this end, non-selective transmit-SENSE pulses were individually tailored for each of 8 subjects under study, and applied to an 8-channel transmit-array. Such RF pulses were designed both for the low-FA excitation train and the 180° inversion preparation involved in the sequence, both utilizing the recently introduced k(T)-point trajectory. The resulting images were compared with those obtained from the conventional method and from subject-specific RF-shimmed excitations. In addition, four of the volunteers were scanned at 3 T for benchmarking purposes (clinical setup without pTx). Subsequently, automated tissue classification was performed to provide a more quantitative measure of the final image quality. Results indicated that pTx could already significantly improve image quality at 7 T by adopting a suitable RF-Shim. Exploiting the full potential of the pTx-setup, the proposed k(T)-point method provided excellent inversion fidelity, comparable to what is commonly only achievable at 3 T with energy intensive adiabatic pulses. Furthermore, the cumulative energy deposition was simultaneously reduced by over 40% compared to the conventional adiabatic inversions. Regarding the low-FA k(T)-point based excitations, the FA uniformity achieved at 7 T surpassed what is typically obtained at 3 T. Subsequently, automated white and gray matter segmentation not only confirmed the expected improvements in image quality, but also suggests that care should be taken to properly account for the strong local susceptibility effects near cranial cavities. Overall, these findings indicate that the k(T)-point-based pTx solution is an excellent candidate for UHF 3D imaging, where patient safety is a major concern due to the increase of specific absorption rates.

kT -points: short three-dimensional tailored RF pulses for flip-angle homogenization over an extended volume.

With Transmit SENSE, we demonstrate the feasibility of uniformly exciting a volume such as the human brain at 7T through the use of an original minimalist transmit k-space coverage, referred to as "k(T) -points." Radio-frequency energy is deposited only at a limited number of k-space locations in the vicinity of the center to counteract transmit sensitivity inhomogeneities. The resulting nonselective pulses are short and need little energy compared to adiabatic or other B 1+-robust pulses available in the literature, making them good candidates for short-repetition time 3D sequences at high field. Experimental verification was performed on three human volunteers at 7T by means of an 8-channel transmit array system. On average, whereas the standard circularly polarized excitation resulted in a 33%-flip angle spread (standard deviation over mean) throughout the brain, and a static radio-frequency shim showed flip angle variations of 17% and up, application of k(T) -point-based excitations demonstrated excellent flip angle uniformity (8%) for a small target flip angle and with sub-millisecond durations.

Factors associated with upper respiratory tract disease caused by feline herpesvirus, feline calicivirus, Chlamydophila felis and Bordetella bronchiseptica in cats: experience from 218 European catteries.

A full history of the management practices and the prevalence of upper respiratory tract disease (URTD) at 218 rescue shelters, breeding establishments and private households with five or more cats was recorded. Oropharyngeal and conjunctival swabs and blood samples were taken from 1748 cats. The prevalences of feline herpesvirus (FHV), feline calicivirus (FCV), Chlamydophila felis and Bordetella bronchiseptica were determined by PCR on swab samples. An ELISA was applied to determine the prevalence of antibodies to B. bronchiseptica. The rates of detection by PCR of each pathogen in the cats in catteries with and without ongoing URTD were, respectively, FHV 16 per cent and 8 per cent; FCV 47 per cent and 29 per cent; C. felis 10 per cent and 3 per cent; and B. bronchiseptica 5 per cent and 1.3 per cent; the seroprevalences of B. bronchiseptica were 61 per cent and 41 per cent, respectively. There was evidence that FHV, FCV and B. bronchiseptica played a role in URTD. The risk factors associated with the disease were less than excellent hygiene, contact with dogs with URTD, and larger numbers of cats in the cattery or household.

[Complications of intraperitoneal chemotherapy by the needle technique. Evaluation after ten years]. / Complications de la chimiothérapie intrapéritonéale par la technique à l'aiguille. Bilan à 10 ans.

A hundred and twenty three patients with intraperitoneal cancer (mostly ovarian) were treated between 1980 and 1990 with intraperitoneal chemotherapy administered through a "needle". Local complications were infinitely fewer and less serious than those observed with materials implanted for months. General complications depended on which protocols were being used. But tolerance on the whole was better when the drugs were administered intraperitoneally. This is particularly clear with cisplatin, although the dose is doubled intraperitoneally over a period of 10 months instead of 6. In this ways there was hardly any neurotoxicity and there was a noteworthy prolongation of survival time in cases of ovarian carcinoma.

[Ovarian carcinomas. Intraperitoneal chemotherapy by needle]. / Carcinomes ovariens. Chimiothérapie intrapéritonéale à l'aiguille.

Between January 1980 and February 1988, 61 women with ordinary ovarian carcinoma (OC) were treated with combined intraperitoneal and intravenous first-line therapy. For intraperitoneal infusions we did not use implanted systems which are often poorly tolerated and sometimes create non-negligible complications. We simply used a lumbar puncture needle left in situ for less than 2 hours. In second regard laparotomies, the 7 patients with stage I OC and the 3 patients with stage II OC were in histologically and cytologically proven complete remission, as were 34 of the 43 patients with stage III OC (79 percent) and 1 of the 8 patients with stage IV OC. After a mean follow-up of 56 months, the overall actuarial survival rate was 66 percent and the survival rate without recurrence was 54 percent. During the same period, 26 patients with recurrent OC were treated with second-line intraperitoneal chemotherapy. After a mean follow-up of 30 months, 10 were in apparently complete remission, and after a 27 to 61 months period 7 of these 10 patients had no recurrence. These results must be compared with those obtained with other salvage methods.

[Airports malaria: findings of a survey in Paris airports (author's transl)]. / Le paludisme des aéroports. Résultats d'une enquête sur les aéroports parisiens.

From 1976 to 1978, thirteen cases of malaria have been reported from France. Ten of them occurred in the vicinity of the airport Roissy-Charles de Gaulle. The entomological investigation which is described there have been performed to evaluate risk of local transmission and to plan prophylactic measures.