Quantitative imaging of magnetic nanoparticles in an unshielded environment using a large AC susceptibility array.

BACKGROUND: Non-invasive magnetic imaging techniques are necessary to assist magnetic nanoparticles in biomedical applications, mainly detecting their distribution inside the body. In Alternating Current Biosusceptometry (ACB), the magnetic nanoparticle's magnetization response under an oscillating magnetic field, which is applied through an excitation coil, is detected with a balanced detection coil system. RESULTS: We built a Multi-Channel ACB system (MC-ACB) containing nineteen pick-up coils and obtained 2D quantitative images of magnetic nanoparticle distributions by solving an inverse problem. We reconstructed the magnetic nanoparticles spatial distributions in a field of view of 14 × 14 cm2 with a spatial resolution of 2.0 cm and sensitivity in the milligram scale. A correlation coefficient between quantitative reconstructed and nominal magnetic nanoparticle distributions above 0.6 was found for all measurements. CONCLUSION: Besides other interesting features such as sufficient large field of view dimension for mice and rat studies, portability, and the ability to assess the quantitative magnetic nanoparticles distributions in real-time, the MC-ACB system is a promising tool for quantitative imaging of magnetic nanoparticles distributions in real-time, offering an affordable setup for easy access in clinical or laboratory environments.

Multiple analyses suggests texture features can indicate the presence of tumor in the prostate tissue.

Several studies have demonstrated statistical and texture analysis abilities to differentiate cancerous from healthy tissue in magnetic resonance imaging. This study developed a method based on texture analysis and machine learning to differentiate prostate findings. Forty-eight male patients with PI-RADS classification and subsequent radical prostatectomy histopathological analysis were used as gold standard. Experienced radiologists delimited the regions of interest in magnetic resonance images. Six different groups of images were used to perform multiple analyses (seven analyses variations). Those analyses were outlined by specialists in urology as those of most significant importance for the classification. Forty texture features were extracted from each image and processed with Random Forest, Support Vector Machine, K-Nearest Neighbors, and Naive Bayes. Those seven analyses variation results were described in terms of area under the ROC curve (AUC), accuracy, F-score, precision and sensitivity. The highest AUC (93.7%) and accuracy (88.8%) were obtained when differentiating the group with both MRI and histopathology positive findings against the group with both negative MRI and histopathology. When differentiating the group with both MRI and histopathology positive findings versus the peripheral image zone group the AUC value was 86.6%. When differentiating the group with negative MRI/positive histopathology versus the group with both negative MRI and histopathology the AUC value was 80.7%. The evaluation of statistical and texture analysis promoted very suggestive indications for future work in prostate cancer suspicious regions. The method is fast for both region of interest selection and classification with machine learning and the result brings original contributions in the classification of different groups of patients. This tool is low-cost, and can be used to assist diagnostic decisions.

Automatic algorithm for quantifying lung involvement in patients with chronic obstructive pulmonary disease, infection with SARS-CoV-2, paracoccidioidomycosis and no lung disease patients.

In this work, we aimed to develop an automatic algorithm for the quantification of total volume and lung impairments in four different diseases. The quantification was completely automatic based upon high resolution computed tomography exams. The algorithm was capable of measuring volume and differentiating pulmonary involvement including inflammatory process and fibrosis, emphysema, and ground-glass opacities. The algorithm classifies the percentage of each pulmonary involvement when compared to the entire lung volume. Our algorithm was applied to four different patients groups: no lung disease patients, patients diagnosed with SARS-CoV-2, patients with chronic obstructive pulmonary disease, and patients with paracoccidioidomycosis. The quantification results were compared with a semi-automatic algorithm previously validated. Results confirmed that the automatic approach has a good agreement with the semi-automatic. Bland-Altman (B&A) demonstrated a low dispersion when comparing total lung volume, and also when comparing each lung impairment individually. Linear regression adjustment achieved an R value of 0.81 when comparing total lung volume between both methods. Our approach provides a reliable quantification process for physicians, thus impairments measurements contributes to support prognostic decisions in important lung diseases including the infection of SARS-CoV-2.

Ischemic stroke enhancement using a variational model and the expectation maximization method.

OBJECTIVES: In order to enable less experienced physicians to reliably detect early signs of stroke, A novel approach was proposed to enhance the visual perception of ischemic stroke in non-enhanced CT. METHODS: A set of 39 retrospective CT scans were used, divided into 23 cases of acute ischemic stroke and 16 normal patients. Stroke cases were obtained within 4.5 h of symptom onset and with a mean NIHSS of 12.9±7.4. After selection of adjunct slices from the CT exam, image averaging was performed to reduce the noise and redundant information. This was followed by a variational decomposition model to keep the relevant component of the image. The expectation maximization method was applied to generate enhanced images. RESULTS: We determined a test to evaluate the performance of observers in a clinical environment with and without the aid of enhanced images. The overall sensitivity of the observer's analysis was 64.5 % and increased to 89.6 % and specificity was 83.3 % and increased to 91.7 %. CONCLUSION: These results show the importance of a computational tool to assist neuroradiology decisions, especially in critical situations such as the diagnosis of ischemic stroke. KEY POINTS: • Diagnosing patients with stroke requires high efficiency to avoid irreversible cerebral damage. • A computational algorithm was proposed to enhance the visual perception of stroke. • Observers' performance was increased with the aid of enhanced images.

Role of sex hormones in gastrointestinal motility in pregnant and non-pregnant rats.

AIM: To correlate gastric contractility, gastrointestinal transit, and hormone levels in non-pregnant (estrous cycle) and pregnant rats using noninvasive techniques. METHODS: Female rats (n = 23) were randomly divided into (1) non-pregnant, (contractility, n = 6; transit, n = 6); and (2) pregnant (contractility, n = 5; transit, n = 6). In each estrous cycle phase or at 0, 7, 14, and 20 d after the confirmation of pregnancy, gastrointestinal transit was recorded by AC biosusceptometry (ACB), and gastric contractility was recorded by ACB and electromyography. After each recording, blood samples were obtained for progesterone and estradiol determination. RESULTS: In the estrous cycle, despite fluctuations of sex hormone levels, no significant changes in gastrointestinal motility were observed. Days 7 and 14 of pregnancy were characterized by significant changes in the frequency of contractions (3.90 ± 0.42 cpm and 3.60 ± 0.36 cpm vs 4.33 ± 0.25 cpm) and gastric emptying (168 ± 17 min and 165 ± 15 min vs 113 ± 15 min) compared with day 0. On these same days, progesterone levels significantly increased compared with control (54.23 ± 15.14 ng/mL and 129.96 ± 30.52 ng/mL vs 13.25 ± 6.31 ng/mL). On day 14, we observed the highest level of progesterone and the lowest level of estradiol compared with day 0 (44.3 ± 15.18 pg/mL vs 24.96 ± 5.96 pg/mL). CONCLUSION: Gastrointestinal motility was unaffected by the estrous cycle. In our data, high progesterone and low estradiol levels can be associated with decreased contraction frequency and slow gastric emptying.

The small bowel flora in individuals with cecoileal reflux.

BACKGROUND: The observation of cecoileal reflux to barium enema is not rare; however, its causes and consequences have not been widely investigated. Considering that ileocecal junction exerts a function as barrier to invasion of bacteria from colon to small bowel, it seems interesting to study the intestinal microflora in subjects carrying cecoileal reflux. AIMS: This study aims at evaluating the ileal flora in individuals with cecoileal reflux. METHODS: A group of 36 subjects comprising 30 females and 6 males with a mean age of 54 years was assessed. Twenty-five individuals with cecoileal reflux and 11 without cecoileal reflux were submitted to small intestine contamination evaluation through the breath test with lactulose-H2 and measurement of the orocecal transit time by means of alternate current biosusceptometry. Small intestine bacterial overgrowth was characterized by orocecal transit time-H2 shortening. RESULTS: Comparison of basal H2, orocecal transit time-H2 and orocecal transit time-alternate current biosusceptometry measurements did not statistically differ between the groups with and without cecoileal reflux. Orocecal transit time-H2 was significantly smaller than orocecal transit time-alternate current biosusceptometry, particularly in individuals with cecoileal reflux. A significant correlation between the two methods was observed only in relation to control, not existing in relation to cecoileal reflux group. CONCLUSIONS: Smaller orocecal transit time-H2 and the loss of correlation with orocecal transit time-alternate current biosusceptometry observed in the individuals with cecoileal reflux suggest a differentiated behavior for such group relative to control, which could be associated with small intestine bacterial overgrowth.

The small bowel flora in individuals with cecoileal reflux / Estudo da flora do delgado em doentes com refluxo cecoileal

BACKGROUND: The observation of cecoileal reflux to barium enema is not rare; however, its causes and consequences have not been widely investigated. Considering that ileocecal junction exerts a function as barrier to invasion of bacteria from colon to small bowel, it seems interesting to study the intestinal microflora in subjects carrying cecoileal reflux. AIMS: This study aims at evaluating the ileal flora in individuals with cecoileal reflux. METHODS: A group of 36 subjects comprising 30 females and 6 males with a mean age of 54 years was assessed. Twenty-five individuals with cecoileal reflux and 11 without cecoileal reflux were submitted to small intestine contamination evaluation through the breath test with lactulose-H2 and measurement of the orocecal transit time by means of alternate current biosusceptometry. Small intestine bacterial overgrowth was characterized by orocecal transit time-H2 shortening. RESULTS: Comparison of basal H2, orocecal transit time-H2 and orocecal transit time-alternate current biosusceptometry measurements did not statistically differ between the groups with and without cecoileal reflux. Orocecal transit time-H2 was significantly smaller than orocecal transit time-alternate current biosusceptometry, particularly in individuals with cecoileal reflux. A significant correlation between the two methods was observed only in relation to control, not existing in relation to cecoileal reflux group. CONCLUSIONS: Smaller orocecal transit time-H2 and the loss of correlation with orocecal transit time-alternate current biosusceptometry observed in the individuals with cecoileal reflux suggest a differentiated behavior for such group relative to control, which could be associated with small intestine bacterial overgrowth.

RACIONAL: Fato de observação não rara, é o encontro de refluxo cecoileal durante realização de enema opaco. As causas e conseqüências deste achado têm sido pouco estudadas. OBJETIVOS: Sabendo que a junção ileocecal exerce função de barreira e proteção contra a invasão do delgado pela flora colônica, realizou-se o presente estudo com a finalidade de investigar se existe contaminação ileal em indivíduos com refluxo cecoileal ao enema opaco. MÉTODOS: Investigaram-se 36 indivíduos, 30 mulheres e 6 homens, idade média de 54 anos, 25 com e 11 com ausência refluxo cecoileal. Todos submetidos a pesquisa de contaminação bacteriana do delgado por intermédio de teste respiratório com lactulose-H2 e a determinação do tempo de trânsito orocecal por meio de biossusceptometria de corrente alternada. A caracterização da contaminação do delgado foi baseada no encurtamento do tempo de trânsito orocecal medido pelo teste da lactulose-H2. RESULTADOS: A comparação dos valores basais do H2, do tempo de trânsito orocecal-H2 e tempo de trânsito orocecal-biossusceptometria de corrente alternada não diferiram estatisticamente entre os grupos com e sem refluxo cecoileal. Quando comparados os tempo de trânsito orocecal-H2 e tempo de trânsito orocecal-biossusceptometria, foi observado aumento de tendência de redução do primeiro em relação ao último nos grupos com refluxo cecoileal e correlação significante entre os dois métodos apenas no grupo-controle, inexistindo nos com refluxo cecoileal. CONCLUSÃO: Encurtamento do tempo de trânsito orocecal-H2 e sua perda de correlação com o tempo de trânsito orocecal-biossusceptometria observado em indivíduos com refluxo cecoileal, sugerem comportamento diferenciado deste grupo em relação ao grupo-controle. Possível explicação para as diferenças registradas entre os grupos, seria a presença de flora anômala nos indivíduos com refluxo cecoileal.