Multiple two-dimensional active shape model framework for right ventricular segmentation

Segmentation of the right ventricle (RV) in MRI short axis images is very challenging due to its complex shape and various appearance among the different subjects and cross-sections. Active shape models (ASM) have shown potential for segmenting the complex structures, including the RV, through two formulations: two- and three-dimensional modeling with a reported trade-off between accuracy and complexity of each formulation. In this work, we propose a new framework for modeling the RV surface using multiple 2D contours, where information from multiple cross-sectional images are incorporated into the same model. The proposed method was tested using cardiac MRI images from 56 human subjects. Compared to a golden reference of manually delineated RV contours, the proposed method resulted in significantly lower error than (almost one half) that of the conventional 2D ASM especially at the apical slices. The mean absolute distance of the proposed method was 2.9 ± 2 mm while the conventional 2D ASM resulted in an error of 6.6 ± 4.5 mm. In addition, the computation time of the proposed method was 5 s compared to 4 ± 1 min previously reported for the 3D ASM formulation.

Detecting liver fibrosis using a machine learning-based approach to the quantification of the heart-induced deformation in tagged MR images

Liver disease causes millions of deaths per year worldwide, and approximately half of these cases are due to cirrhosis, which is an advanced stage of liver fibrosis that can be accompanied by liver failure and portal hypertension. Early detection of liver fibrosis helps in improving its treatment and prevents its progression to cirrhosis. In this work, we present a novel noninvasive method to detect liver fibrosis from tagged MRI images using a machine learning-based approach. Specifically, coronal and sagittal tagged MRI imaging are analyzed separately to capture cardiac-induced deformation of the liver. The liver is manually delineated and a novel image feature, namely, the histogram of the peak strain (HPS) value, is computed from the segmented liver region and is used to classify the liver as being either normal or fibrotic. Classification is achieved using a support vector machine algorithm. The in vivo study included 15 healthy volunteers (10 males; age range 30-45 years) and 22 patients (15 males; age range 25-50 years) with liver fibrosis verified and graded by transient elastography, and 10 patients only had a liver biopsy and were diagnosed with a score of F3-F4. The proposed method demonstrates the usefulness and efficiency of extracting the HPS features from the sagittal slices for patients with moderate fibrosis. Cross-validation of the method showed an accuracy of 83.7% (specificity = 86.6%, sensitivity = 81.8%).

MRI T2* imaging for assessment of liver iron overload: study of different data analysis approaches

Background Recently, magnetic resonance imaging (MRI) has been established as an effective technique for evaluating iron overload by measuring T2* in the liver. Purpose To investigate the effects of various factors associated with T2* calculation on the resulting measurement and to determine the analysis criterion that provides the most accurate T2* measurements. Material and Methods Both phantom and in vivo MRI experiments were conducted to study the effects of the selected region of interest (ROI) location and size, signal-averaging method, exponential-fitting model, echo truncation, iron-overload severity, and inter-/intra-observer variabilities on T2* measurements. The results were compared to reference values from the scanner processing software. Results The pixel-by-pixel calculation method provided results in better agreement with the reference values from the MRI scanner than the average or median methods. The choice of the exponential fitting model affected the results, depending on signal-to-noise ratio, number of echoes, minimum and maximum echo times, and tissue composition inside the selected ROI. The single-exponential model resulted in smaller error than the bi-exponential or exponential-plus-constant models, where the latter two models showed similar results. The relative performance of the different models and methods was not affected by the degree of iron-overload. Conclusion Various factors associated with the adopted T2* calculation method affect the resulting measurement. In this study, the pixel-by-pixel calculation method and single-exponential model provided the most accurate results based on the conducted phantom and in vivo MRI experiments.

Influence of the analysis technique on estimating hepatic iron content using MRI

PURPOSE

To investigate the effect of the analysis technique on estimating hepatic iron content using MRI.

MATERIALS AND METHODS

We evaluated the influences of single-exponential (EXP), bi-exponential (BEXP), and exponential-plus-constant (CEXP) models; and pixel-wise (MAP), average (AVG), and median (MED) signal calculation methods on T2* measurement using numerical simulations, calibrated phantoms, and nine patients scanned on 3 Tesla MRI, based on regression, correlation, and t-test statistical analysis.

RESULTS

The T2* measurement error varied from 9 to 51% in the numerical simulations (T2*: 5-20 ms), depending on signal-to-noise ratio (SNR; range: 8-233) with significant (P < 0.05) difference between actual and predicted values. The MAP method performed well (error < 10%) at high SNR (>100), but resulted in severe estimation errors at low SNR (<50). The EXP model resulted in significant measurement differences (P < 0.05) compared with all other methods, irrespective of SNR. In vivo T2* values ranged from 3.1 to 53.6 ms, depending on the amount of iron overload and implemented analysis method. The BEXP (range: 3.7-50 ms) and CEXP (range: 3.8-53.6 ms) models, and the AVG (range: 3.2-38.8 ms) and MED (range: 3.1-38.5 ms) methods provided more accurate measurements than the EXP model (range: 3.1-18.3 ms) and MAP (range: 3.8-53.6 ms) method, respectively (P < 0.05). The BEXP and CEXP models provided very similar measurements (P > 0.87). Similarly, the AVG and MED methods provided very similar results (P > 0.97), with slightly better performance of the AVG method.

CONCLUSION

Different analysis techniques show different performances based on the fitting model and signal calculation method. Based on this study, the CEXP model and AVG method are recommended due to simpler implementation and less influence by the selected analysis region. J. Magn. Reson. Imaging 2016;44:1448-1455.

Hybrid intensity- and phase-based optical flow tracking of tagged MRI

Accurate tracking of the myocardium tissues in tagged Magnetic Resonance Images (MRI) is essential for evaluating the cardiac function. Current tracking methods utilize either the image intensity or the image phase as landmarks that can be tracked. In either case, the performance is vulnerable to the image quality and the fading of the tag lines. In this work, we propose a hybrid optical flow tracking method that combines both the intensity and the phase features of the image. The method is validated using numerical cardiac phantom as well as real MRI data experiments. Both experiments showed that the proposed method outperforms current intensity-based optical flow tracking and the phase-based HARP method with maximum error of 1 pixel at extreme conditions of tag fading.

Automatic synthesis of cine viability MRI images for evaluation of coronary heart disease

Coronary heart disease (CHD) is the leading cause of death worldwide. Cardiac magnetic resonance imaging (MRI) is a valuable imaging modality, as it can noninvasively provide information about myocardial function, viability, and morphology. Viability delayed-enhancement (DE) images are acquired at a single timeframe while myocardial functional (tagged) images are acquired as a cine loop of timeframes throughout the cardiac cycle. In this work, we propose a method for estimating DE images at all timeframes in the cardiac cycle without additional scan time to show both viability and functional information in the same image. The method is based on generating a dense motion field of the heart from the acquired tagged images, and then applying the extracted field to the acquired DE image. The developed technique is accurate in generating cine DE images and providing simultaneous information about myocardial viability and wall motion for comprehensive patient evaluation and optimal treatment selection.

The influence of the analysis technique on estimating liver iron overload using magnetic resonance imaging T2* quantification

Iron toxicity is the major cause of tissue damage in patients with iron overload. Iron deposits mainly in the liver, where its concentration closely correlates with whole body iron overload. Different techniques have been proposed for estimating iron content, with liver biopsy being the gold standard despite its invasiveness and influence by sampling error. Recently, magnetic resonance imaging (MRI) has been established as an effective technique for evaluating iron overload by measuring T2(*) in the liver. However, various factors associated with the adopted analysis technique, mainly the exponential fitting model and signal averaging method, affect the resulting measurements. In this study, we evaluate the influences of these factors on T2(*) measurement in numerical phantom, calibrated phantoms, and nine patients with different degrees of iron overload. The results show different performances among the fitting models and signal averaging methods, which are affected by SNR, image quality and signal homogeneity inside the selected ROI for analysis.

Tag removal in cardiac tagged MRI images using coupled dictionary learning

Tagged Magnetic Resonance Imaging (tMRI) is considered to be the gold standard for quantitative assessment of the cardiac local functions. However, the tagging patterns and low myocardium-to-blood-pool contrast of tagged images bring great challenges to cardiac image processing and analysis tasks such as myocardium segmentation and tracking. Hence, there has been growing interest in techniques for removing tagging lines. In this work, a method for removing tagging patterns in tagged MR images using a coupled dictionary learning (CDL) model is proposed. In this model, identical sparse representations are assumed for image patches in the tagged MRI and corresponding cine MRI image spaces. First, we learn a dictionary for the tagged MRI image space. Then, we compute a dictionary for the cine MRI image space so that corresponding tagged and cine patches have the same sparse codes in terms of their respective dictionaries. Finally, in order to produce the de-tagged (cine version) of a test tagged image, the sparse codes of the tagged patches and the trained cine dictionary are used together to construct the de-tagged patches. We have tested this tag removal method on a dataset of tagged cardiac MR images. Our experimental results compared favorably with a recently proposed tag removal method that removes tags in the frequency domain using an optimal band-stop filter of harmonic peaks.

A collaborative resource to build consensus for automated left ventricular segmentation of cardiac MR images

A collaborative framework was initiated to establish a community resource of ground truth segmentations from cardiac MRI. Multi-site, multi-vendor cardiac MRI datasets comprising 95 patients (73 men, 22 women; mean age 62.73±11.24years) with coronary artery disease and prior myocardial infarction, were randomly selected from data made available by the Cardiac Atlas Project (Fonseca et al., 2011). Three semi- and two fully-automated raters segmented the left ventricular myocardium from short-axis cardiac MR images as part of a challenge introduced at the STACOM 2011 MICCAI workshop (Suinesiaputra et al., 2012). Consensus myocardium images were generated based on the Expectation-Maximization principle implemented by the STAPLE algorithm (Warfield et al., 2004). The mean sensitivity, specificity, positive predictive and negative predictive values ranged between 0.63 and 0.85, 0.60 and 0.98, 0.56 and 0.94, and 0.83 and 0.92, respectively, against the STAPLE consensus. Spatial and temporal agreement varied in different amounts for each rater. STAPLE produced high quality consensus images if the region of interest was limited to the area of discrepancy between raters. To maintain the quality of the consensus, an objective measure based on the candidate automated rater performance distribution is proposed. The consensus segmentation based on a combination of manual and automated raters were more consistent than any particular rater, even those with manual input. The consensus is expected to improve with the addition of new automated contributions. This resource is open for future contributions, and is available as a test bed for the evaluation of new segmentation algorithms, through the Cardiac Atlas Project (www.cardiacatlas.org).

Diagnosis of Blastocystis hominis by different staining techniques

One hundred and fifty stool samples were collected from diarrheic patients of different ages, and examined for Blastocystis hominis by direct smears and concentrated by Sheather's sugar flotation. Staining was done by: Giemsa, two modifications of trichrome stain, modified Ziehl-Neelsen, safranin-methylene blue and two-auramine stains. Out of the 150 cases nine were positive for blastocystosis. The best stains were safranin-methylene blue and modified Ziehl-Neelsen stains. They had the advantage of staining cysts and amoeboid forms besides being rapid and easy to perform. The modified trichrome stains identified 8 ie, less specific and were time consuming. The auramine dyes stained the cyst, both the wall and internal body fluoresced brightly. Giemsa stain was not an efficient stain. Scanning and transmission electron microscopy (SEM, TEM) were performed to study the fine ultrastructure.

Genetical and electron microscopical studies on Cryptosporidia

The present work was to clarify whether C. parvum oocysts have different strains in human patients by using different staining, electron microscopical and genetical techniques. A trial to induce a vaccine against Cryptosporidial infection in mice was carried out using killed autoclaved Cryptosporidial oocysts. The results obtained were satisfactory. Two genotypes of C. parvum, viz: human and zoonotic genotypes were detected and described. The killed vaccine used orally gave a promising results.

In-pouch TV culture system in diagnosis of Trichomonas vaginalis infection

A newly simplified culture method, the In-Pouch TV culture system, the wet mount (WM) examination and the acridine orange stain were compared with the Oxoid culture as a standard technique in the diagnosis of trichomoniasis. Out of 70 symptomatic cases enrolled in this study, 28 specimens were positive by all methods. Among these positive specimens, 21 were positive by the Oxoid culture (75%) and 24 (85.7%) with sensitivity of 85.7% by the In-Pouch system. Both wet mount preparation and acridine orange stain had less sensitivity than the In-Pouch system (61.9%) and detected 15 (53.6%) and 16 (57.1%) of the cases respectively. The In-Pouch system has been proved to be easier in the transport and culture technique than the ordinary culture method. It alleviates the need to enter the culture, thus prevents contamination. Its cost is comparable to the ordinary culture tube. Therefore, it is recommended to use the In-Pouch culture system as a method of diagnosing trichomoniasis.

Effect of ozone on the viability of some protozoa in drinking water

Water samples from household tanks in several districts of Alexandria, were examined for protozoa contamination and study to the effect of ozone and chlorine on their viability. The parasitic protozoa encountered were Giardia (56%), Cryptosporidia (50%), Blastocystis (12%), Cyclospora (9%) and Microsporidia (3%). Distilled water was treated by ozone or chlorine. Ozonated-water samples were prepared at a concentration of 1 ppm after contact times with ozone of three, five, seven and nine minutes. Chlorine concentrations were 4 and 8 ppm. Parasites were incubated overnight at room temperature with the treated distilled water. Viability of the parasites was assessed by examining intestinal sections of infected animals. The best results were obtained by using ozonated water after a contact time of nine minutes. Giardia, Cryptosporidia and Microsporidia were completely inactivated, while infectivity of Cyclospora and Blastocystis was markedly reduced. It is suggested that ozone at an appropriate concentration inactivate pathogenic protozoa in water.

A comparison between human, crustacean and bivalve isolates of Microsporidia

Identification of Microsporidia detected in diarrhoeic stool of human and from press preparation of crabs, and bivalves muscles was done by staining with Giemsa, modified trichrome and H & E stains respectively. Positive samples were isolated & used for infection of 3 groups of mice viz group A human isolate, group B crab & group C bivalve isolates. Parasitological and histopathological studies using light and transmission electron microscopy (TEM) were done for samples from each group. The results clarified that human, crab & bivalve Microsporidia isolates showed common features. They were found in the supranuclear region of enterocytes. The stages observed were meronts, sporonts and free spores. Each spore was 1-2 um in length containing a single nucleus, a vacuole and a polar filament. Further genetical and biochemical studies will be undertaken to confirm the similarity or differences between these isolates.

Coccidial infection in immunosuppressed mice: prophylaxis and treatment with dehydroepiandrosterone

Cryptosporidiosis and toxoplasmosis are diseases caused by opportunistic coccidial parasites that can lead to life-threatening infection in immunocompromised patients. We evaluated dehydroepiandrosterone as prophylaxis and therapy in immunosuppressed mice infected with Cryptosporidium parvum and avirulent Toxoplasma gondii. Mice were infected with either Cryptosporidium oocysts or Toxoplasma cysts. Assessment was by mortality rates, parasitic counts and electron microscopic studies. Mortality rates were significantly reduced in all treated groups. A significant reduction in the cryptosporidial oocyst count in stool and intestinal villi and in Toxoplasma cysts in the brains of infected mice was observed in all the groups. The effect of the drug was greater when given prior to infection.

Detection of Cryptosporidium parvum antigen by co-agglutination test and ELISA

Confirmation of the presence of Cryptosporidium in environmental samples is laborious, costly and often difficult. We report here a simple and economic slide agglutination test (co-agglutination test) for detecting cryptosporidial antigen in stool, serum and water. The results show that as a screening method co-agglutination is clearly superior to enzyme-linked immunosorbent assay (ELISA) and modified Ziehl-Neelsen staining, although ELISA is more accurate. The co-agglutination test is recommended for application as a new tool for detecting cryptosporidial antigen in large-scale epidemiological surveys.

Electroencephalographic changes in rats received antigens of different parasites

The prevalence of epilepsy in developing countries is much higher than in developed ones. Some of the highest prevalence rates in developing countries have been reported from tropical Africa where parasitic infections are endemic. This work was carried out to assess the effect of different parasitic antigens on the activity of cerebral cortex in rats. Nine crude antigens were used: Adult Fasciola, adult S. mansoni, hydatid cyst, T. spiralis, E. histolytica, Acanthamoeba spp. G. lamblia, Cryptosporidium spp. and crude antigen of T. gondii. All the parasitic antigens induced electroencephalographic changes compared with baseline tracings.

Detection of Cryptosporidia in different water sources in Alexandria by monoclonal antibody test and modified Ziehl Neelsen stain

Cryptosporidium paruum has become one of the most important contaminant found in drinking water and is associated with high risk of waterborne diseases particularly for the immunocompromised. In the present study, Cryptosporidium was found in uncovered water tanks, nearby the shore in El Noubareya and El Mahmoudeya canals and in one swimming pool. Direct flourescence monoclonal antibody was more sensitive in detecting the organism. Ziehl-Neelsen although less sensitive, yet it has the advantage that it could recognize other protozoa causing diarrhoea as G. lamblia, B hominis and Cyclospora sp.

Aminosidine sulphate in experimental giardiasis

Giardia lamblia infection may be asymptomatic or may produce diarrhea with or without malabsorption. Many drugs were used for treatment of giardiasis, but none proved to be ideal since all have potential troublesome side effects as they are absorbed from the intestine. In this study, a locally acting drug aminosidine-sulphate (gabbroral) has been tried in treatment of experimental giardiasis in a rat model under different conditions of gastric acidity which is one of the main local factors affecting the pathogenicity of the organism. The best results were obtained in the group with hyperacidity which was induced by indomethacin (indocid) with significant improvement in the pathological picture and parasitic count. While in experimental animals with normal acidity there was only partial eradication of the parasite. However, in the group with hypoacidity induced by cimetidine (cimetex), the drug showed no beneficial effects since most organisms invaded the deeper layers of the intestine escaping the local action of the drug.

Aminosidine sulphate in experimental cryptosporidiosis

The present study aimed at investigating the efficiency of a recent antibiotic Aminosidine sulphate (Gabbroral) in experimental cryptosporidiosis. The course of infection was studied when the drug was given early before the infection, and late during the infection both parasitologically and histopathologically. When the drug was given early, the results were satisfactory, with a significant reduction of size, number and pathological changes of the parasites in the stool and in ileal sections of infected mice. However, the drug had no effect when given late during the infection.

A study on experimental cryptosporidiosis

Cryptosporidium oocysts were isolated from stools of infected patients diagnosed as cryptosporidiosis. Suckling Swiss albino mice were infected orally by these oocysts in a dose of 10(6) oocysts/mouse. Mice were divided into 9 groups according to the duration of infection 2, 3, 4, 5, 6, 7, 10, 10, 15, 21 days postinfection, corresponding non infected control groups were included. Stools of infected mice were examined twice daily to determine; infection rate, prepatent period and intensity of infection. Mice were sacrificed according to the schedule and the whole intestine was isolated and processed for histopathological examination by H & E and modified Ziehl Nielsen stain, and histochemical examination for acid and alkaline phosphatase activity. The results revealed that the infection rate was 90% and prepatent period 3-5 days and the course of infection was 21 days. The maximum pathological changes were in the ileum. These changes were reversible.

Contraception and community in Egypt: a preliminary evaluation of the population/development mix

Egypt's Population and Development Program (PDP) is an effort to combine family planning and development approaches at the grass roots level. Introduced as a pilot project in the late 1970s, it is now active in nearly three quarters of Egypt's villages. A 1980 Contraceptive Prevalence Survey of over 5,000 rural women stratified 124 villages according to their exposure to the program (from zero to two or more years). Comparison of women living in villages of varying exposure revealed no differences in fertility; but modest differences in knowledge, attitudes, and contraceptive practice were apparent, especially in Upper Egypt. A multivariate analysis with socioeconomic and demographic controls did not weaken these relationships. Moreover, program effects were most marked among those most in need of services--noncontracepting fecund women who were illiterate.

Turbulence measurements with pulsed Doppler ultrasound employing a frequency tracking method

A phase lock loop method of tracking doppler ultrasound frequencies is applied to the measurement of turbulent velocities. A pulsed Doppler ultrasound system capable of detecting two velocity components was employed to resolve axial and radial velocity components at the centerline of turbulent pipe flows and distal to stenoses in pulsatile flow. Measurements with the ultrasound system are compared with laser Doppler and hot film anemometer data. The results demonstrate that the phase lock loop method of tracking accurately follows turbulent velocity fluctuations for turbulence intensities up to approx. 20%, after which signal dropout becomes a significant factor. An important application of the method is that of detecting flow disturbances created by mild to moderate degrees of stenosis in arterial disease.

The influence of wife's education on fertility in rural Egypt

Based on survey data from rural Egypt, the effects of the wife's education on fertility and family planning were investigated and shown to be very important. In accordance with the results of most other studies, there is an inverse relationship with the number of live births. The wife's education is also shown to influence attitudes towards family size, spacing, and knowledge and approval of contraceptives, all of which lead to a high proportion of contraceptive use and help to achieve the desired family size. There was also a clear inverse association between the wife's education and pregnancy loss and infant mortality; these latter two variables showed positive correlations with the number of live births.

(Summary in Arabic on p. 60)