Functional MRI Based Brain Mapping in Occipital Gyrus using Face Stimuli

Functional magnetic resonance imaging (fMRI) is one of the most powerful neuroimaging modalities due to its high spatio-temporal resolution characteristics. This known modality is applied on mapping the temporal, occipital, frontal cortices of the brain for localizing the neural activities generated due to any visual, physical or mental task or brain diseases or brain disorders. The occipital cortex is composed of middle, left, right, interior and exterior occipital gyrus and is responsible for visional function of human brain. The occipital gyrus reflects the neural image generated in the brain due to any visual activity. In this research paper, four different visual stimuli images of faces, scrambled, scenes and objects along with gap of blank space, forming a long sequence of stimuli observed by two female subjects, are experimented to examine and localize the most contrasting neural image generated in occipital gyrus of the brain. The visual fMRI brain data received from the two subjects is processed through fMRI-SPM12 toolbox based on Matlab software. In order to demonstrate the results statistically, two regressions such as T-contrast and F-contrast vectors are applied on fMRI images to highlight, and to localize the most active neural stimuli activities generated in the occipital gyrus of brain. In the results, it is demonstrated that maximum neural response can be mapped only for face stimulus in the bilateral occipital gyrus of the brain by applying T-contrast vectors regressions as when compared to other stimuli conditions and F-contrast vectors regressions. Further, it is also investigated that, the response of the face stimulus in F-contrast regressions achieved is somehow dispersed and unclear due to the large variances and interlinked communication of other stimuli or induced neural noises generated in entire volume of the brain.  Further from the given images, it is also investigated that the most reflecting and contrast area for any visual stimuli (such as face stimulus in this case) is either the middle or bilateral part of occipital gyrus of the human brain as identified through application of  T-contrast vectors regressions.

Evaluating the Diagnostic Performance of an Initial Transvaginal Sonogram Tvs in Patients With Suspected Ectopic Pregnancy

Purpose of the study: To evaluate the diagnostic performance of an initial transvaginal sonogram (TVS) in patients with suspected ectopic pregnancy (EP). Objectives: 1) To determine the accuracy, sensitivity, specificity, positive and negative predictive values of an initial TVS scan in patients with suspected EP. 2) To determine the diagnostic utility of TVS findings as predictors of EP. Methodology: This was a descriptive, prospective study of 131 consecutive mothers who had TVS for clinical suspicion of EP at the Aga Khan University hospital over a 12 month period between November 2007 and October 2008. The scans were performed in our radiology department by sonographers, residents and consultant radiologists. The mothers were followed-up to determine their clinical or surgical outcome, which was then used as a reference standard. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value for the initial TVS and sonographic predictors of EP were calculated. The study was approved by the University Research and Ethics Committee. Results: The accuracy of an initial TVS in this study was 96% (126 / 131). Sensitivity, specificity, PPV and NPV of initial TVS was 84% (21 / 25), 99% (105 / 106), 95.5% (21 / 22) and 96.3% (105 / 109) respectively. The prevalence of EP in our study was 19.08 % (25 / 131). In this study, 69.4% (91/131) of mothers had intrauterine pregnancies while 10.4% of them were not gravid. Adnexal mass, hemoperitoneum and tubal ring sign had high specificities but low sensitivities. Presence of an extrauterine gestational sac with or without an embryo was associated with 100% specificity and PPV. Conclusion: This study demonstrates that initial TVS is a highly accurate and reliable tool in the evaluation of mothers with clinical suspicion of ectopic pregnancy. With the high accuracy, specificity and predictive values more than 95% of mothers will be evaluated correctly.