Generating a minimal set of templates for the hippocampal region in MR neuroimages.

OBJECTIVES: We detail a procedure for generating a set of templates for the hippocampal region in magnetic resonance (MR) images, representative of the clinical conditions of the population under investigation. METHODS: The first step is robust standardization of the intensity scale of brain MR images, belonging to patients with different degrees of neuropathology (Alzheimer's disease). So similar tissues have similar intensities, even across images coming from different sources. After the automatic extraction of the hippocampal region from a large dataset of images, we address template generation, choosing by clusterization methods a small number of the extracted regions. RESULTS: We assess that template generation is largely independent on the clusterization method and on the number and the clinical condition of the patients. The templates are chosen as the most representative images in a population. The estimation of the "minimum" number of templates for the hippocampal region can be proposed, using a metric based on the geometrical position of the extracted regions. CONCLUSIONS: This study describes a simple and easily reproducible procedure to generate templates for the hippocampal region. It can be generalized and applied to other brain regions, which may be relevant for neuroimaging studies.

Suprapubic percutaneous sclero-embolization of symptomatic female pelvic varicocele under local anesthesia.

PURPOSE: To evaluate the safety and feasibility of supra-pubic percutaneous sclero-embolization (SE) in the treatment of symptomatic female pelvic varicocele (FPV), performed under local anesthesia. MATERIALS AND METHODS: The authors selected 28 patients screened by transabdominal and transvaginal ultrasound, with venous Doppler signal. Clinicians performed SE by transfemoral catheterization, under local anesthesia, using of a mix of 2 ml of lauromacrogol 400 (Atossisclerol 3%, Chemische F. Kreussler, Wiesbaden, Germany) and 2 ml of air, in a mixed foam fashion. RESULTS: The total operative time for SE was 7.6 +/- 2.1 min. Intra-surgical blood loss was 40 +/- 14 ml. No migration of sclerosant material occurred and postoperative analgesic request during a 48 hr period occurred in 6 patients. Technical success was 100%. The Authors embolized 8 women bilaterally (28.5%), 18 on the left ovarian vein (OV) (64.2%) and 2 only in the right OV (7.1%): 7 women complained of transitory flank pain (25%), which disappeared in few minutes. The major complications in 10 days after SE were: fever (> 38 degrees C for two days) in 2 patients (7.1%) and pelvic pain for 3 days in eight patients (28.5%). After 30 days only 6 women suffered of FPV lower symptoms which disappeared in 180 days. A substantial reduction in size of pelvic varicosities was noted in all patients. CONCLUSIONS: SE is a safe and feasible procedure. It reduces significantly the mean time of scopies, the intensity of radiation emission, and it is performed under local anaesthesia. This minimally invasive procedure could be proposed to all women with supra-pubic FPV for its reproducibility and feasibility.

Intrapartum sonography head transverse and asynclitic diagnosis with and without epidural analgesia initiated early during the first stage of labor.

PURPOSE: To investigate if early epidural analgesia can influence fetal head engagement into the pelvis and if it can increase the rate of transverse and asynclitic position during labour. MATERIALS AND METHODS: 195 women with combined spinal-epidural analgesia (CSE) or without neuraxial analgesia were studied. CSE was performed using a mixture of ropivacaine 0.02% with 0.3 microg/ml of sufentanil administered in the spinal space. Maintenance of analgesia was managed with intermittent epidural administration of 10-15 ml of ropivacaine (0.07%-0.10%) mixed with 0.5 microg/ml of sufentanil, based on the stage of labour and the degree of pain. 2D transabdominal ultrasound (US) was used. Serial transabdominal US examinations were performed at 45-90 min intervals to detect transverse and asynclitic positions, using the following signs: squint sign, sunset thalamus and cerebellum signs that best details the fetal head station. After delivery, the complete set of clinical and US data obtained by each examination were recorded and compared in women with and without labour analgesia. Data were examined by independent reviewers. RESULTS: There was no difference in obstetric outcome between women in whom CSE had been used and those who did not request analgesia during labour (p > 0.05). CONCLUSIONS: Epidural analgesia initiated early during labour and using low doses does not increase the rate of dystocic labors. Transverse fetal head positioning with anterior or posterior asynclitism does not seem to be promoted by drug or technique-related mechanisms, but rather should be the consequence of cephalopelvic disproportion.

Pleural nodule identification in low-dose and thin-slice lung computed tomography.

A completely automated system for the identification of pleural nodules in low-dose and thin-slice computed tomography (CT) of the lung has been developed. The directional-gradient concentration method has been applied to the pleura surface and combined with a morphological opening-based procedure to generate a list of nodule candidates. Each nodule candidate is characterized by 12 morphological and textural features, which are analyzed by a rule-based filter and a neural classifier. This detection system has been developed and validated on a dataset of 42 annotated CT scans. The k-fold cross validation has been used to evaluate the neural classifier performance. The system performance variability due to different ground truth agreement levels is discussed. In particular, the poor 44% sensitivity obtained on the ground truth with agreement level 1 (nodules annotated by only one radiologist) with six FP per scan grows up to the 72% if the underlying ground truth is changed to the agreement level 2 (nodules annotated by two radiologists).

A completely automated CAD system for mass detection in a large mammographic database.

Mass localization plays a crucial role in computer-aided detection (CAD) systems for the classification of suspicious regions in mammograms. In this article we present a completely automated classification system for the detection of masses in digitized mammographic images. The tool system we discuss consists in three processing levels: (a) Image segmentation for the localization of regions of interest (ROIs). This step relies on an iterative dynamical threshold algorithm able to select iso-intensity closed contours around gray level maxima of the mammogram. (b) ROI characterization by means of textural features computed from the gray tone spatial dependence matrix (GTSDM), containing second-order spatial statistics information on the pixel gray level intensity. As the images under study were recorded in different centers and with different machine settings, eight GTSDM features were selected so as to be invariant under monotonic transformation. In this way, the images do not need to be normalized, as the adopted features depend on the texture only, rather than on the gray tone levels, too. (c) ROI classification by means of a neural network, with supervision provided by the radiologist's diagnosis. The CAD system was evaluated on a large database of 3369 mammographic images [2307 negative, 1062 pathological (or positive), containing at least one confirmed mass, as diagnosed by an expert radiologist]. To assess the performance of the system, receiver operating characteristic (ROC) and free-response ROC analysis were employed. The area under the ROC curve was found to be Az = 0.783 +/- 0.008 for the ROI-based classification. When evaluating the accuracy of the CAD against the radiologist-drawn boundaries, 4.23 false positives per image are found at 80% of mass sensitivity.

Deposition of SiO2 films with high laser damage thresholds by ion-assisted electron-beam evaporation.

SiO(2) thin films (approximately 100 nm thick) with transmittivity and a laser damage threshold nearly equal to those of bulk material are deposited on silica substrates by the technique of ion-assisted electron-beam evaporation. The influence of film packing density on the laser damage threshold is investigated by the technique of photoacoustic probe beam deflection. It is shown that films with lower packing density may have a higher laser damage threshold and as a consequence better heat dissipation.

Beam-divergence control of excimers with plane-parallel Gaussian cavities.

Plane-parallel cavities with Gaussian-reflectivity-profile mirrors as full reflectors were applied to a XeCl laser, and the near- and the far-field characteristics of the laser radiation were analyzed. It is shown that excimer lasers fitted with plane-parallel Gaussian cavities deliver laser radiation with a beam-quality factor M(2) that is more than 50% smaller than that of laser beams delivered by conventional plane-parallel cavities. The effect of the Gaussian mirror spot size on M(2) was also investigated, and it is shown that the narrowing of the Gaussian mirror spot size reduces the beam-quality-factor value.