nan Thet-Thet-Lwin

Iodine imaging in thyroid by fluorescent X-ray CT with 0.05 mm spatial resolution

Abstract Fluorescent X-ray computed tomography (FXCT) at a 0.05xa0mm in-plane spatial resolution and 0.05xa0mm slice thickness depicted the cross sectional distribution of endogenous iodine within thyroid. The distribution obtained from the FXCT image correlated closely to that obtained from the pathological pictures.

Visualization of age-dependent myocardial metabolic impairment in cardiomyopathic model hamster obtained by fluorescent X-ray computed tomography using I-127 BMIPP

Fluorescent X-ray computed tomography (FXCT) enables visualization of myocardial fatty acid metabolism by using non-radio-iodinated I-5-(p-iodophenyl)-3-(R,S)-methylpentadecanoice acid (BMIPP). In this experiment, age-dependent myocardial metabolic impairment was successfully imaged and analyzed quantitatively in J2N-k cardiomyopathic hamster using FXCT.

Preliminary quantitative analysis of myocardial fatty acid metabolism from fluorescent X-ray computed tomography imaging.

Fluorescent X-ray computed tomography (FXCT) using synchrotron radiation reveals the cross-sectional distribution of specific elements in biomedical objects. The aim of this study was to investigate the feasibility of FXCT imaging to assess the myocardial metabolic state quantitatively. Hearts labelled with non-radioactive iodine myocardial fatty acid agent 15-p-(iodophenyl)-3-methylpentadecanoic acid (BMIPP) from cardiomyopathic and normal hamsters were imaged. FXCT images were compared with optical microscope images. Myocardial fatty acid metabolism enhanced with BMIPP was clearly depicted by FXCT, which showed an almost homogeneous image for normal and a heterogeneous image for cardiomyopathic hearts. Morphological structures of the heart such as the left ventricle and myocardial wall were also visualized by FXCT. Optical microscopy showed no fibrosis in normal and slight interstitial fibrosis in cardiomyopathic hearts. In the case of cardiomyopathy, the area of significantly reduced BMIPP uptake was 39% in the short axis of the mid-left ventricle in the FXCT image, whereas a slight interstitial fibrosis of around 12% was recognized by optical microscopy for the same slice. This result indicated that reduced BMIPP uptake was caused by the myocardial fatty acid metabolic abnormality, not by the fibrosis in cardiomyopathy. Thus, FXCT images might be used to assess the quantitative metabolic analysis in small animal models of heart diseases.

99mTc-N-DBODC5: A Novel Myocardial Perfusion Imaging Agent for Diagnosis of Coronary Artery Disease, a Review

In myocardial SPECT imaging with the popularly used 99mTc-sestamibi and 99mTc-tetrofosmin, intense liver uptake leads to a paradoxical decrease of counts in the absence of perfusion abnormalities, making it difficult to assess myocardial perfusion, particularly in the inferior or inferoapical left ventricular wall. 99mTc-N-DBODC5, which is a new lipophilic, mono-cationic nitride myocardial perfusion imaging agent, exhibits high myocardial uptake and excellent bio-distribution kinetics with rapid liver clearance in rats and dogs. 99mTc-N-DBODC5 myocardial imaging during vasodilator stress can determine the severity of stenosis, though underestimates occur with mild coronary stenosis compared to 201Tl, in a similar way to what occurs with 99mTc-sestamibi and 99mTc-tetrofosmin. In particular, 99mTc-N-DBODC5s rapid liver clearance, which may significantly reduce the photon scatter from the liver, allows for the reduction of artifactual decreased myocardial perfusion and the improvement of the diagnostic accuracy of coronary artery disease.

Quantitative evaluation of heart disease by integration of MRI and SPECT images

We tried to evaluate the blood flow in left ventricle quantitatively by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission tomography (SPECT). Paired MRI and myocardial perfusion SPECT from 16 patients including apical hypertrophic cardiomyopathy (APH) and normal subjects were considered. Blood flow per unit myocardium volume was calculated by 3-D surface-based registration between MRI and SPECT images.

High-accuracy Myocardial Detection by Combining Level Set Method and 3D NURBS Approximation

Accurate detection of myocardium is much important in diagnosis of heart diseases. In this study, we proposed the myocardial detection method by combining level set method in 2D image and 3D NURBS approximation. We first extracted epi- and endocardial walls by level set method in 2D image. Calculation cost was reduced by the processing on the slice. In this extraction, we used a near-circular shape of left ventricle and set the initial circle in the myocardial region surrounding the endocardium. We then approximated these extracted walls with 3D NURBS (Non-uniformed rational Bspline) model. Here, we used third-order B-spline basis function. In our study, we applied the method to MRI T1-weighted heart images of 10 subjects (5 normal subjects and 5 patients with apical hypertrophic cardiomyopathy). The pixel size was 1.62 x 1.62 mm, and the slice interval and the number of slices were 6.62 mm and 18, respectively. Evaluation of our method was done by comparing with manual detection by two cardiologists. As a result, the accuracy of endocardial detection was about the same as or less than the difference between cardiologists. While on the other hand, that of epicardial detection was larger than the difference between cardiologists. We inferred that epicaridial contour is clearer than endocardial one. Average of detection error by the method combining level set method and NURBS approximation (endocardium: 2.58 mm / epicardium: 2.71 mm) was smaller or almost same as only level set method (2.77 mm / 2.51 mm). However, as for variance of the error, combining method (0.58 mm / 0.59 mm) was smaller than only level set method (1.07 mm / 1.06 mm). These results show that NURBS approximation suppressed the variation of the detection accuracy.

Cerebral perfusion imaging of live mice by fluorescent X-ray CT

Fluorescent X-ray CT (FXCT), which has high-contrast and high-spatial resolution, is being developed for in-vivo biomedical research. Since FXCT could depict the specific heavy atomic number elements in the order of picogram, the functional imaging resembling to single photon emission CT can be obtained. We have applied this technique for in-vivo and ex-vivo biomedical imaging. FXCT system consists of a silicon (111) double crystal monochromator, an x-ray slit system, a scanning table for object positioning, fluorescent x-ray detectors, and pin-diode detectors. Using non-radioactive iodine labeled IMP, cerebral perfusion of a live mouse was clearly demonstrated at a 1 mm spatial resolution and a 0.1 mm slice thickness. In addition, the structure of extracted mouse brain fixed by formalin was depicted much clearly at 0.5 mm spatial resolution due to the availability of long data acquisition time. Thus, the success of in-vivo FXCT imaging with high resolution allows starting to new approach of bio-imaging research.