Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation.

Liquid crystal "Blue Phases" (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

[Place of hand-held gamma-cameras in breast cancer]. / Place des gamma-caméras portables en cancérologie mammaire.

Non-palpable breast cancers are more and more frequent. Their surgical management requires the excision of the tumor and sentinel lymph node (SLN) needing a technical preoperative organization combining preoperative identification of the tumor by wire guide and injection of a radioactive tracer for the identification of SLN. The implementation of this minimally invasive surgery is sometimes paradoxically complicated due to the presurgical organization requiring several medical teams. It is for this reason that hand-held gamma-cameras have been developed, used either preoperatively or during surgery to replace lymphoscintigraphy but also as a help to excision of the tumor after radioisotope injection. The objective of this study was to evaluate the interest of the main hand-held gamma-cameras used in breast cancer.

[Image quality and optical density in mammography: study on phantoms]. / Qualité image et densité optique en mammographie: étude sur fantôme.

Optical densisty (od) is an important factor for image quality in mammography. We studied the effect of o.d. on the image score with two phantoms (Contrast Detail MAMmography phantom (CDMAM), University Hospital Nijmegen, The Netherlands and breast-equivalent phantom (MTM 100) made by CIRS in the United States). We also evaluated the doses required to obtain the blackening considered from measurements made with thermoluminescent pastilles. Two series of exposure were performed at 28 kV with mAs ranging from 25 to 100 to obtain a range of o.d. varying between 0.72 and 2.67. Image scores were then evaluated for each negative by calculating the mean of five different readers. The study showed a clear increase of the image score with o.d. These observations were consistent with other studies. For the two phantoms and the screen-film combination used, the maximum quality was obtained for an o.d. of 1.6, but the drawback of negatives at high o.d. is increase of the irradiation dose from 5,4 to 7,2 mGy when the o.d. increases from 1.30 to 1.70.

[Ductal carcinoma in situ of the breast: role of imaging]. / Carcinome canalaire in situ du sein: place de l'imagerie.

The incidence of ductal carcinoma in situ (DCIS) has increased with the widespread use of screening mammography. DCIS is often suspected when clustered microcalcifications are evidenced on routinely performed mammography. High quality mammographies are required and should be completed with magnification views. Mammographic--pathologic correlations are described according to the new classifications as well as unusual forms of presentation on mammography. Early contrast enhancement in DCIS on dynamic MRI is reported and seems to be related with angiogenesis. A wire localization procedure of non-palpable lesions has to be performed and per-operative specimen radiography is mandatory. Stereotaxic large core needle biopsy is a valuable alternative to surgical biopsy but a multidisciplinary team approach is necessary and follow-up is recommended if no excisional biopsy is done. Quality in the management of DCIS depends on the coherence of the "multidisciplinary team".

Breast carcinoma located in ectopic breast tissue: a case report and review of the literature.

Ectopic breast tissue usually develops along the mammary ridge. The incidence of this anomaly has been reported as high as 6%. Malignant development is rare. A case of carcinoma of aberrant breast tissue, located in the axilla is described. Mammographies of the ectopic breast performed few years before the diagnosis of carcinoma are presented and also those done for the diagnosis of the tumor. A literature study was performed on carcinoma and ectopic breast tissue. Considering high frequence of node involvements for these cases, the optimal therapeutic strategies are discussed.

[Mesenteric panniculitis. Aspects in x-ray computed tomography and MRI]. / Panniculite mésentérique. Aspects en scanographie et en IRM.

We report one case of mesenteric panniculitis. This rare and poorly-known disease is characterized by a non specific inflammatory process involving adipose tissue of the mesentery. The new imaging techniques (CT and MRI) may be helpful for the diagnosis of this disease and allow avoiding laparotomy. However histological proof remains necessary and can be given by guided needle biopsy.

[Current role of x-ray computed tomographic test in the detection of lesions of peritoneal carcinomatosis]. / Place actuelle de l'examen tomodensitométrique dans la détection des lésions de carcinomatose péritonéale.

CT scan is presently the method of choice in the pre-operative evaluation of patients with peritoneal carcinomatosis. The aim of this article is to present the results of a personal work concerning the comparison of CT scan and the surgical data in the diagnosis of peritoneal carcinomatosis and to compare them with data of the literature. Despite the existence of unavoidable bias related to the retrospective characteristic of the study, the results confirm the good sensitivity of the scan in the examination of peritoneal carcinomatosis, through it remains insufficient to do without surgical exploration.

[Diagnostic and therapeutic characteristics of breast cancer in elderly women. Groupe Sein du Centre Alexis Vautrin]. / Particularités diagnostiques et thérapeutiques du cancer du sein de la femme âgée. Groupe Sein du Centre Alexis Vautrin.

Because of its high incidence and the high number of deaths induced, breast cancers in elderly women is a major health problem. The diagnosis is often clinical and the tumors are often at advanced stage with many initial metastases due to some neglect. Breast cancer in elderly women has no specific radiological form and is more often infiltrating ductal carcinoma of SBR grade I. Hormonal receptors are generally higher in elderly than in young women. Surgery of breast cancers with equal anesthetic risks factors does not induce more complications in elderly women than in the general population. In 12% of cases, an associated pathology influences the decision (degradation of the respiratory or cardiovascular function or reduction of the renal function). Between 70 and 80 years, provided that life expectancy is compatible with radiotherapy, corollary to conservative treatments in the present state of our knowledge for tumors under 3 to 4 cm, there is an alternative between radiosurgical conservative treatment and modified mastectomy associated with axillary dissection. In case of bulky tumors (> 3 to 4 cm) and failure of the hormonal treatment or impossibility to perform a complementary radiotherapy treatment (for instance, senile dementia), of axillary node involvement, a fortiori if the tumor has no hormonal receptors, the modified mastectomy with axillary dissection remains the therapeutic standard. In case of bulky tumor, the hormonal status can be used to induce the patient to accept an operation and, if necessary, to perform a conservative surgery. However, despite hormonosensitivity of breast cancer, a tumoral progression after a mean duration of hormonosensitivity of 25 months is to be expected in 93% of the cases, included 25% in whom a complete response to hormonotherapy was observed. A fractionated irradiation delivering 2 Gy per fraction and 5 fractions per week with a total number of sessions of 25 gives better esthetical results. This optimal treatment lasts 5 weeks and the patients often get tired since they are old and their radiotherapy centre is far from their house. Therefore hypofractionated treatment (once a week) should be proposed. The adjuvant medical treatment of reference for menopausal women is hormonotherapy by tamoxifen. Breast cancer in elderly women reduces life expectancy at 5 years by 50%; the theoretical therapeutic indications are the same as for young women, but their application is adapted to the patient. It would be dangerous and illusive to undertreat such a disease when the life expectancy is longer than 3 years.

[Cat-scratch disease presenting as a pseudotumor. Imaging by x-ray computed tomography and MRI]. / Maladie des griffes du chat de présentation pseudotumorale. Aspect en scanographie et en IRM.

Cat-scratch disease is usually a self-limiting illness but it can initially present as a tumor. A case of a lesion of the arm is described, with CT and MR findings. The radiologic appearance is not characteristic but the diagnosis can be suggested in a predisposing clinical setting.