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Search Results: 1 - 10 of 5202 matches for " Imaging "
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Holographic microwave imaging for medical applications  [PDF]
Lulu Wang, Ray Simpkin, A. M. Al-Jumaily
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.68100
Abstract: This paper presents a new 2D holographic microwave imaging array (HMIA) technique for medical imaging applications. The HMIA technique has been applied to early stage breast cancer detection and brain stroke detection. Computer models are developed to demonstrate the feasibility of detecting and localizing small brain strokes within a 2D numerical head model and breast tumours within a 3D numerical breast model using the HMIA technique. Experimental validation of the HMIA simulation model using a breast phantom has been undertaken and demonstrated a good agreement between experimental and simulated images. Simulation and experimental results showed that the proposed HMIA technique has the potential to become a powerful medical screening and diagnostic tool.

Lesion contrast differences in MRI sequences in multiple sclerosis: Correlation to clinical disability  [PDF]
Maija Rossi, Minna Raunio, Pertti Ryymin, Irina Elovaara, Prasun Dastidar
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.63A041
Abstract:

The purpose of this study was to analyze the lesion brightness (image contrast) in multiple MRI sequences in patients with relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), primary progressive MS (PPMS), and clinically isolated syndrome (CIS); and to correlate the lesion contrast with lesion volumes and neurological disability. MRI ex- amination at 1.5 T was performed on 80 patients with RRMS, SPMS, PPMS, or CIS. The protocol included T1- and T2-weighted spin echo (SE), fluid attenuated inversion recovery (FLAIR), T1-weighted SE with magnetization transfer preparation, and diffusion weighted imaging (DWI). Contrast was measured between MS lesions and normal appearing white matter. Lesion volume was calculated in T1-weighted- and FLAIR-images. All patients were examined neurologically including evaluation of expanded disability status scale (EDSS) score. Lesion contrast correlated with total brain lesion volume (p = 0.000 - 0.040). In patients with low EDSS, three sequences were able to differentiate between CIS and RRMS. SPMS and PPMS were separated by DWI. Lesion contrast correlated with EDSS score on T1-weighted imaging, with or without magnetization transfer preparation. Patient age correlated with lesion contrasts. Contrast measurements seem limited in radiological and clinical diagnosis of MS in reference to disease course, its activity and progression. The differentiation between MS subgroups might improve at 3 T and could help in leading to earlier treatment of the disease.

Natural course of ovarian torsion after untwisting: A case report with radiographic imaging  [PDF]
Dmitry Fridman, Muhammad Faisal Aslam, Neekianund Khulpateea
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.21007
Abstract: Background: Radiographic studies largely contribute to prompt diagnosis of ovarian torsion, though post-operative changes are not described and might contribute to unnecessary intervention. Case: We report a case of ovarian torsion diagnosed based on clinical presentation and radiographic findings. The detorsion was successfully performed through laparosopic access. Subsequently patient presented for elective ultrasonography and MRI which diagnosed multicystic ovarian mass, attributed to hematoma which resolved spontaneously with no intervention in 3 weeks. Conclusion: Ovarian changes after detorsion consistent with development of hematoma may be benign and resolve spontaneously.
Holographic Microwave Imaging Array for Brain Stroke Detection  [PDF]
Lulu Wang, A. M. Al-Jumaily, Ray Simpkin
Journal of Signal and Information Processing (JSIP) , 2013, DOI: 10.4236/jsip.2013.43B017
Abstract:

This paper proposes a new holographic microwave imaging array (HMIA) technique for brain stroke detection. This approach is based on holographic microwave and aperture synthesis imaging techniques. The system is designed for operation at a single frequency of 2.5 GHz. A realistic three dimensional (3D) head model that contains skin, fat, skull, cerebrospinal fluid (CSF), grey matter, white matter and ischemic or hemorrhagic stroke area is developed using MATLAB to demonstrate the proposed HMIA imaging algorithm.A matching solution medium is used between the antennas and the head model. The study is conducted using HMIA computer simulations and 3D head model with-stroke.The simulation results showed that small stroke area (5 mmin diameter) could be successfully detected with the HMIA approach.

Medical Image Acquisition and Processing: Clinical Validation  [PDF]
Michael L. Goris
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.44028
Abstract: The validation of medical imaging (processing and acquisition) can be achieved in multiple ways, somewhat influenced by the context. There are three traps to avoid: First reliance on ground truth requires the knowledge of it before the end of the trial, second comparison to gold standards cannot show improvement and finally one needs to deal with confirmation bias. In this paper we discuss those topics and alternative validation schemes.
Hypothalamic Hamartomas: Two Cases  [PDF]
Tushar Kalekar
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.51003
Abstract: This is a MRI study of two patients presented with history of gelastic seizures since many years ago. Plain and post intravenous gadolinium multiplanar MRI imaging of the brain is performed. It showed well-defined non-enhancing mass lesions in the region of hypothalamus and tuber cinereum. It showed signal intensity similar to the gray matter and imaging diagnosis of hypothalamic hamartoma is made.
A New Method of Tracking of WM Crossing Fiber Bundles Based on QBI  [PDF]
Zhanxiong Wu
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B051
Abstract:

Tracking of crossing WM fiber bundles can be resolved using diffusion MRI imaging. DTI can only resolve a single fiber orientation within each voxel due to the constraints of the tensor model. DSI requires large pulsed field gradients and time-intensive sampling. This paper puts forward with a new method based on QBI, which uses a spherical tomographic inversion called Funk-Radon transform to get high angular resolution diffusion imaging signal. From the tracking results, we can get the conclusion that QBI-tracking can resolve crossing fiber time-savingly.

MRI of the Bladder in Patients Suspected of Bladder Tumors  [PDF]
Karen Lind Gandrup, J?rgen Nordling, Henrik S. Thomsen
Open Journal of Radiology (OJRad) , 2014, DOI: 10.4236/ojrad.2014.42028
Abstract: Objective: To prospectively evaluate the use of MRI for the detecting of bladder tumors and the T- stage using T2W, T1W and diffusion-weighted images (DWI). Material and methods: Twenty-eight consecutive patients (21 men, 7 women; age range, 20 - 82 years; mean age, 62.8 years) suspected of bladder tumors underwent MRI, flexible cystoscopy and transurethral resection (TURB). The presence of bladder tumor was confirmed by histopathology in 21 patients; 18 patients had pTa, one pT1 and two pT2. The images were reviewed by two uroradiologists. They assigned the presence of a bladder tumor and whether the tumor was non-muscle invasive (Ta and T1) or muscle- invasive (T2, T3 or T4). Results: Compared to the histopathological results, the accuracy for identifying a bladder tumor was 60.7% and 53.7% for reviewer A and B, respectively. The sensitivity and specificity were 66.7%/61.9% and 57.1%/42.9%. Positive predictive values were 82.6%/ 76.5%. The overall staging was correct in 47.6%/52.5%, but improved on stage-by-stage up to 50%/66.7%. The agreement between the reviewers was moderate in the detecting, staging and location of the tumor (Kappa = 0.47 - 0.57). Conclusion: A simple MRI using no contrast media, but DWI, cannot replace flexible cystoscopy in the detection of new or recurrent bladder tumors.


Dynamic Contrast-Enhanced MRI of Mouse Liver: A Feasibility Study Using a Dual-Input Two-Compartment Tracer Kinetic Model  [PDF]
Septian Hartono, Choon Hua Thng, Kai Hsiang Chuang, Huynh Hung, Tong San Koh
Journal of Biomedical Science and Engineering (JBiSE) , 2015, DOI: 10.4236/jbise.2015.82009
Abstract: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been widely applied to evaluate microcirculatory parameters in clinical settings. However, pre-clinical studies involving DCE-MRI of small animals remain challenging with the requirement for high spatial and temporal resolution for quantitative tracer kinetic analysis. This study illustrates the feasibility of applying a high temporal resolution (2 s) protocol for liver imaging in mice by analyzing the DCE-MRI datasets of mice liver with a dual-input two-compartment tracer kinetic model. Phantom studies were performed to validate the T1 estimates derived by the proposed protocol before applying it in mice studies. The DCE-MRI datasets of mice liver were amendable to tracer kinetic analysis using a dual-input two-compartment model. Estimated micro-circulatory parameters were consistent with liver physiology, indicating viability of applying the technique for pre-clinical drug developments.
Application of Magnetic Particle Imaging to Pulmonary Imaging Using Nebulized Magnetic Nanoparticles  [PDF]
Kohei Nishimoto, Atsushi Mimura, Marina Aoki, Natsuo Banura, Kenya Murase
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.52008
Abstract: Purpose: To investigate the feasibility of applying magnetic particle imaging (MPI) to pulmonary imaging using nebulized magnetic nanoparticles (MNPs) and to quantify the mucociliary clearance in the lung, using small animal experiments. Materials and Methods: Intrapulmonary administration of MNPs was performed in seven-week-old male ICR (Institute of Cancer Research) mice (n = 8) using a nebulized microsprayer connected to a high-pressure syringe containing 50 μL of MNPs (500 mM Resovist®). We imaged the lungs using our MPI scanner 2.5 hours, 1 day, 3 days, and 7 days after the intrapulmonary administration of MNPs. The average MPI value was calculated by drawing a region of interest (ROI) on the lungs by taking the threshold value for extracting the contour as 20% of the maximum MPI value within the ROI. The MPI value was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. Mice were sacrificed immediately after the last MPI and X-ray CT studies on day 7, and 5 lobes of the lung in each mouse were extracted to confirm the accumulation of iron using Berlin blue staining. Results: We could visualize the distribution of MNPs in the lungs as positive contrast using MPI with use of nebulized MNPs. The presence of iron in the lung was confirmed by Berlin blue staining. The average MPI value decreased with time and tended to saturate. The clearance rate was calculated to be 0.505 day1 from the time course of the average MPI value in the lungs. Conclusion: Our preliminary results suggest that MPI can be applied to pulmonary imaging by nebulizing MNPs and can be useful for quantifying the mucociliary clearance in the lung.
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