Two-dimensional intravenous coronary arteriography using above-K-edge monochromatic synchrotron X-ray

RATIONALE AND OBJECTIVES: For intravenous (i.v.) coronary arteriography, a real-time two-dimensional (2D) imaging system is being developed using above-K-edge monochromatic X-rays alone. The potential diagnostic value of this system was examined in the current study. METHODS: The angiographic system consisted of an asymmetric silicon (311) monocrystal, an image intensifier, and a charged-coupled device camera. It was constructed at the beam line of the Tristan Accumulation Ring. Monochromatic X-rays of 33.32 keV were used, and each image was recorded over 2 msec. RESULTS: Ventricular wall motion and the anatomy of the coronary arteries could be seen in dogs by sequential images obtained without subtraction. The left anterior descending coronary artery, left circumflex coronary artery, and right coronary artery and the branches of these vessels were observed. The parts of the coronary arteries overlapping the aorta and left ventricle were revealed somewhat during washout of the contrast material. CONCLUSION: For a 2D imaging system, monochromatic i.v. coronary angiography using an energy above the iodine K-edge might be able to image the coronary arteries without subtraction. However, the image quality needs to be improved by increasing the X-ray flux, decreasing background radiation scatter from the object, and decreasing contamination with 99-keV X-rays.     

Oligodendrogliomas. Part II: A new grading system based on morphological and imaging criteria

Myocardial perfusion scintigraphy is a noninvasive diagnostic method for the evaluation of patients with suspected or proven coronary artery disease (CAD). We utilized case-based reasoning (CBR) methods to develop the computer-based image interpretation system SCINA which automatically derives from a scintigraphic image data set an assessment concerning the presence of CAD. We compiled a case library of 100 patients who underwent both perfusion scintigraphy and coronary angiography to document or exclude the presence of CAD. The angiographic diagnosis of the retrieved nearest neighbor match of a scintigraphic input case was selected as the CBR diagnosis. We examined the effects of input data granularity, case indexing, similarity metric, and adaptation on the diagnostic accuracy of the CBR application SCINA. For the final prototype, sensitivity and specificity for detection of coronary heart disease were 98% and 70% suggesting that CBR systems may achieve a diagnostic accuracy that appears feasible for clinical use.     

Factors contributing to retinal detachment after transscleral fixation of posterior chamber intraocular lenses

Coronary arteries are segmented from the blood pool using mathematical morphology operations from a 3D magnetic resonance spiral acquisition on a continuously breathing healthy volunteer. The segmented volume is maximal intensity projected at different views to yield coronary angiograms showing the left anterior descending artery (LAD), right coronary artery (RCA), and left circumflex artery (LCX). Magnetic resonance coronary angiography provides a retrospective rotating view of the coronary artery tree that complements oblique reformatted sections.     

Beta-lactamase-producing bacteria in recurrent childhood tonsillitis

Angiotensin converting enzyme is a key component of the renin angiotensin system that plays an important role in cardiovascular regulation. It seems to modulate cardiovascular growth by virtue of its role in the conversion of angiotensin I to angiotensin II and degradation of kinins. A deletion polymorphism localized in intron 16 of the human angiotensin converting enzyme gene, corresponding to a 287 bp long Alu repetitive sequence, was found to be associated with increased risk of myocardial infarction in various subgroups, including European, French and Japanese coronary patients. This angiotensin converting enzyme gene I/D polymorphism was examined by the polymerase chain reaction in a cross-sectional study of 201 healthy Indian subjects and 150 patients (angiographically proven cases of coronary artery disease) whose serum angiotensin converting enzyme levels were concomitantly measured. The D/D, I/D and I/I genotypes were found in 20.66%, 46.66% and 32.66% of the Indian coronary heart disease patients and in 23.38%, 49.75% and 26.86% of controls respectively. One of the reasons for not finding an association between the D allele and coronary artery disease in this study could be the ethnic heterogeneity and disease status heterogeneity among the patients and controls. However the phenotypic variance of serum angiotensin converting enzyme levels is strongly influenced by this polymorphism. In the Indian population, the angiotensin converting enzyme gene I/D polymorphism is not associated with risk for coronary artery disease although it is associated with plasma angiotensin converting enzyme activity. Hence the angiotensin converting enzyme gene I/D polymorphism does not seem to be a useful marker for coronary artery disease in the Indian population.     

Three-dimensional respiratory-gated MR angiography of coronary arteries: comparison with conventional coronary angiography

OBJECTIVE: MR coronary angiography is most often performed using two-dimensional techniques. Although three-dimensional (3D) acquisitions do have important advantages, they take too long for a single breath-hold and are thus susceptible to respiratory motion artifacts. The purpose of this study was to investigate the accuracy of a unique respiratory-gated 3D MR angiographic technique in identifying the proximal coronary arteries in patients suspected of having coronary artery disease. In addition, we investigated the capability of this technique to detect proximal stenoses. SUBJECTS AND METHODS: We performed a prospective blinded study in 20 patients who were referred for conventional coronary angiography. A cardiac-gated 3D gradient-echo sequence with fat suppression was used. Retrospective respiratory gating was performed using navigator echoes of the diaphragm position. Using multiplanar reformatting, two independent readers blindly analyzed the data sets for visualization of major coronary arteries, lengths of imaged segments, and detection of significant stenoses (> 50% occlusion of the luminal diameter by conventional angiography). RESULTS: Seventy-seven of 80 (96%) coronary arteries were positively identified. In one patient, an anomalous coronary anatomy was readily identified and confirmed by conventional angiography. The average lengths of the imaged segments of the right, left main, left anterior descending, and left circumflex coronary arteries were 58 +/- 13 mm, 9 +/- 5 mm, 59 +/- 16 mm, and 24 +/- 10 mm, respectively. Overall sensitivity for the detection of stenoses was low (38%), with a specificity of 95%. Interobserver agreement was 0.92, with a kappa value of 0.65. CONCLUSION: Respiratory-gated 3D MR angiography allows accurate identification of proximal coronary arteries and may be valuable for 3D imaging of coronary anomalies. Further technical improvements are required to enhance the value of the technique in detecting stenoses.     

Contrast-enhanced magnetic resonance imaging of the coronary arteries. A review

The advent and continued improvement of T1-shortening contrast media have revolutionized magnetic resonance angiography (MRA) of the entire body in recent years. The technical basis for contrast-enhanced MRA is fast three-dimensional (3D) imaging. A brief historic review of the technical advances in MR coronary artery imaging clearly points to the importance of improved gradient capabilities that led to the development and wide application of fast 3D imaging. The use of contrast agents in coronary artery imaging has been expected for many years, given its success in other parts of the body. Nevertheless, because of the potential difficulties and unique characteristics of fast 3D imaging in the heart, the utility of contrast agents in coronary artery imaging has been systematically investigated only in the last 2 years. Initial experience from our group and others showed that contrast agents have great potential in pushing MR coronary artery imaging to a much higher level in terms of speed and signal-to-noise ratio (SNR), and intravascular agents are more desirable than extracellular agents. Nevertheless, because of the technical challenges and the diversity of methods used for coronary artery imaging, much more effort is needed to continue to improve the imaging techniques and further to define the roles of contrast agents in coronary artery imaging.     

Basic principles and historical consideration of MR cholangiopancreatography

Basic principle of MR cholangiopancreatography (MRCP) is heavily T2-weighted imaging (hydrography) to use bile and pancreatic juice as "natural contrast medium". Firstly developed sequence for MRCP was a CE-FAST sequence, which employed time-reversed FID signal. The current most popular sequences for MRCP are single-shot fast spin-echo sequences, which are divided into three types (2D single slice, 2D mutiple slice and 3D methods). The advantage of 2D single slice method is conveniently obtained projection imaging within a few seconds of examination time. Both 2D multiple slice and 3D methods consists of a MIP image and a series of source images. The MIP image creates global images of pancreatico-biliary system. The source images provide detailed evaluation of various anatomical structures and abnormalities. By using these sequences properly, MRCP can yield valuable informations of pancreatico-biliary diseases non-invasively.     

Three-Dimensional Structural Translation and Rotation Measurement Using Monocular Videogrammetry

Measuring displacement for large-scale structures has always been an important yet challenging task. In most applications, it is not feasible to provide a stationary platform at the location where its displacements need to be measured. Recently, image-based technique for three-dimensional (3D) displacement measurement has been developed and proven to be applicable to civil engineering structures. Most of these developments, however, use two or more cameras and require sophisticated calibration using a total station. In this paper, we present a single-camera approach that can simultaneously measure both 3D translation and rotation of a planar target attached on a structure. The intrinsic parameters of the camera are first obtained using a planar calibration board arbitrarily positioned around the target location. The obtained intrinsic parameters establish the relationship between the 3D camera coordinates and the two-dimensional image coordinates. These parameters can then be used to extract the rotation and translation of the planar target using recorded image sequence. The proposed technique is illustrated using two laboratory tests and one field test. Results show that the proposed monocular videogrammetric technique is a simple and effective alternative method to measure 3D translation and rotation for civil engineering structures. It should be noted that the proposed technique cannot measure translation along the direction perpendicular to the image plane. Hence, proper caution should be taken when placing target and camera.     

Fasting and nonfasting iodine-123-idophenylpentadecanoic acid myocardial SPECT imaging in coronary artery disease

Iodine-123-labeled idophenylpentadecanoic acid (IPPA) metabolic imaging has been shown to be clinically useful for the identification of myocardial viability in patients with coronary artery disease and left ventricular dysfunction. Imaging is usually performed under fasting conditions since nonfasting conditions may affect myocardial uptake of 123I-IPPA. The purpose of this study was to examine the impact of dietary condition on 123I-IPPA metabolic imaging. METHODS: Forty patients with stable coronary artery disease underwent, in randomized order and on separate days, 123I-IPPA SPECT myocardial imaging under fasting and nonfasting conditions. Patients were injected with 123I-IPPA (4-5 mCi) at rest with imaging performed at 4 (initial) and 30 (delay) min. For each image (initial and delay images), 10 segments were analyzed by three experienced observers without knowledge of patient identity or dietary condition using a 5-point grading system (O = no uptake to 4 = normal uptake). A summed global score was obtained for each image by adding the scores for all 10 segments. Image quality was assessed using a 3-point grading system. RESULTS: Visual agreement for normal and abnormal segments between fasting and nonfasting conditions was 82% (kappa = 0.63). There were no significant differences in the summed global scores for both conditions. Image quality was equivalent for both conditions in 65% of cases and superior under the nonfasting condition in 25% of cases. CONCLUSION: Image quality as well as the presence, location and severity of defects are similar under fasting and nonfasting conditions with 123I-IPPA. Therefore, fasting is not necessary before 123I-IPPA SPECT imaging for the assessment of myocardial viability.     

Bridge Damage Assessment through Fuzzy Petri Net Based Expert System

The reliability of the techniques adopted for damage assessment is important for bridge management systems. It is widely recognized that the use of expert systems for bridge damage assessment is a promising direction toward bridge management systems. However, several important issues need to be addressed, such as the management of uncertainty and imprecision, the efficiency of fuzzy rule based reasoning, and the need of an explanation facility to increase confidence about the assessment results. To address the issues arising from using expert systems, this paper is aimed at developing an expert system for assessing bridges based on an expert system shell, which is called the fuzzy Petri net based expert system (FPNES). Major features of FPNES include the ability to reason using uncertain and imprecise information, knowledge representation through the use of hierarchical fuzzy Petri nets, a reasoning mechanism based on fuzzy Petri nets, and an explanation of the reasoning process through the use of hierarchical fuzzy Petri nets. Therefore, this expert system for assessing bridges does not impose any restriction on the inference mechanism. Furthermore, this approach offers more informative results than other systems. An application to the damage assessment of the Da-Shi bridge in Taiwan is used as an illustrative example of FPNES.     

Gd-enhanced 3D phase-contrast MR angiography and dynamic perfusion imaging in the diagnosis of renal artery stenosis

The objective of this study was to investigate the role of contrast enhancement using a three-dimensional (3D) phase-contrast (PC) magnetic resonance (MR) sequence (3D PC-MRA) and to assess the value of a dynamic MR perfusion study of the kidneys to determine the hemodynamic relevance of unilateral renal artery stenosis (RAS). Seventeen patients with unilateral RAS were examined on a standard 1.0 T imaging system using a phase shift and magnitude sensitive 3D PC sequence (TR=160 ms, TE=9 ms, venc. 30 cm/s). Following the initial pre-contrast 3D PC-MRA a dynamic first pass perfusion study was performed using a Turbo-FLASH 2D sequence (TR=4.5 ms, TE=2.2 ms, TI=400 ms) after bolus injection of 0.15 mmol gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)/kg body weight. The 3D PC-MRA was then repeated during infusion of 0.15 mmol Gd-DTPA/kg body weight. Evaluation by three independent readers was based on maximum intensity projection images. Source images were rendered on request. Signal intensity (SI) over time curves of the renal cortex were obtained from the dynamic perfusion study and analyzed for maximum signal enhancement as well as temporal relationship to the aortic SI curve. Results from 3D PC-MRA revealed a sensitivity (pre-/post-contrast) of 100%/89%, specificity of 76%/63%, positive predictive value of 80%/69 %, negative predictive value of 90%/78%, and accuracy of 85%/75% (p=0.07). Interobserver agreement was kappa=0.61/kappa=0.47 (pre/post Gd-DTPA), respectively. Increased signal-to-noise was present in all segments of the renal arteries post contrast (p=0.0003). This came along with image degradation due to aliasing and elevated SI of venous flow that partially obscured the renal arteries. Dynamic SI curves showed a significantly decreased maximum SI in RAS (p=0.01-0.001). A temporal delay of cortical signal intensity enhancement could not be confirmed in this setting. Gd-enhanced 3D PC-MRA did not yield a superior diagnostic value in the diagnosis of RAS compared to pre-contrast measurements. Dynamic perfusion imaging of the kidneys, in combination with 3D PC-MRA, can contribute additional information in suspected unilateral RAS.     

Scintigraphic diagnosis of coronary artery disease: myocardial bull's-eye images contain the important information

The bull's-eye image, also called polar map image, has been developed as an important display for the visual and quantitative analysis of myocardial perfusion scintigrams. Quantitative analysis can be performed for example by comparing areas in the bull's-eye image with normal limits or by processing it using artificial neural networks. The usefulness of such methods is highly dependent on the information content of the bull's-eye image. The purpose of this study was to investigate whether there is more diagnostically important information in a set consisting of the myocardial bull's-eye image plus tomographic slice image than in the bull's-eye image alone. A population of 135 patients who had undergone both myocardial scintigraphy and coronary angiography, with no more than 3 months elapsing between the two examinations, was studied retrospectively. Four experienced observers independently classified visually all scintigrams regarding the presence/absence of coronary artery disease in two vascular territories using a four-grade scale. The observers classified the scintigrams once viewing bull's-eye images only, and once viewing tomographic slices and bull's-eye images. Coronary angiography was used as gold standard. The classifications were evaluated using the areas under the receiver operating characteristics (ROC) curves. The classifications based on bull's-eye images only were slightly more accurate than those based on tomographic slices and bull's-eye images in one of the two vascular territories (ROC areas of 0.66 vs. 0.64). The opposite relationship was found in the other vascular territory (0.78 vs. 0.81). None of the differences was statistically significant. In conclusion, the diagnostically important information for the diagnosis of coronary artery disease by myocardial perfusion scintigraphy is present in the bull's-eye image.     

Assessment of ventricular wall motion and volume by fast cine MRI using Fastcard sequence

Left ventricular wall motion and volume are important factors for assessment of cardiac function. Recent advances in magnetic resonance imaging(MRI) have allowed fast cine MR sequences. Fastcard sequence is an electrocardiographically triggered gradient echo sequence with k-space segmentation and have enabled fast cine acquisition of the heart during breath holding. Improvement in image quality and contrast between myocardium and intraventricular cavity may facilitate assessment of cardiac function using the phased array coil. Drug stress MRI for detection of significant coronary artery stenosis could be more easily performed by this sequence than conventional cine MR sequences. Sequential short axis images obtained with Fastcard sequence also provide an accurate method without assumption of ventricular shape.     

Value of reversed saphenous vein in minimally invasive direct coronary artery bypass graft procedures

BACKGROUND: Minimally invasive direct coronary artery bypass graft procedures are gaining acceptance for revision as well as primary coronary revascularization. When suitable, the left and right internal mammary arteries are preferred as bypass conduits; in other cases, the greater saphenous vein, used for standard coronary artery bypass graft procedures, may be useful to revascularize coronary artery branches during minimally invasive direct coronary artery bypass graft procedures. METHODS: We used the greater saphenous vein on three occasions during minimally invasive direct coronary artery bypass graft procedures (1) to revascularize the left anterior descending coronary artery by anastomosis to the left axillary artery in the infraclavicular region, (2) as an extension to the left internal mammary artery to reach the left anterior descending coronary artery, and (3) as a bridge from the splenic artery to bypass the distal right coronary artery. RESULTS: Postoperatively, all 3 patients had relief from symptoms of coronary artery insufficiency and none has been readmitted to the hospital with symptoms. Angiography or thallium studies were not performed to confirm graft patency because all patients were elderly and the risks of these procedures were considered to outweigh their potential benefit. CONCLUSIONS: The greater saphenous vein is a potential bypass conduit for use in minimally invasive direct coronary artery bypass graft procedures as well as for coronary artery bypass graft procedures.     

Accurate three-dimensional reconstruction of intravascular ultrasound data. Spatially correct three-dimensional reconstructions

BACKGROUND: The geometrical accuracy of conventional three-dimensional (3D) reconstruction methods for intravascular ultrasound (IVUS) data (coronary and peripheral) is hampered by the inability to register spatial image orientation and by respiratory and cardiac motion. The objective of this work was the development of improved IVUS reconstruction techniques. METHODS AND RESULTS: We developed a 3D position registration method that identifies the spatial coordinates of an in situ IVUS catheter by use of simultaneous ECG-gated biplane digital cinefluoroscopy. To minimize distortion, coordinates underwent pincushion correction and were referenced to a standardized calibration cube. Gated IVUS data were acquired digitally, and the spatial locations of the imaging planes were then transformed relative to their respective 3D coordinates, rendered in binary voxel format, resliced, and displayed on an image-processing workstation for off-line analysis. The method was tested by use of phantoms (straight tube, 360 degrees circle, 240 degrees spiral) and an in vitro coronary artery model. In vivo feasibility was assessed in patients who underwent routine interventional coronary procedures accompanied by IVUS evaluation. Actual versus calculated point locations were within 1.0 +/- 0.3 mm of each other (n = 39). Calculated phantom volumes were within 4% of actual volumes. Phantom 3D reconstruction appropriately demonstrated complex morphology. Initial patient evaluation demonstrated method feasibility as well as errors if respiratory and ECG gating were not used. CONCLUSIONS: These preliminary data support the use of this new method of 3D reconstruction of vascular structures with use of combined vascular ultrasound data and simultaneous ECG-gated biplane cinefluoroscopy.     

Engineering Analysis with Uncertainties and Complexities, Using Reasoning Approaches

Conventional computation methods generally limit practicing engineers from using complex formulations or considering uncertainties in general. A method is needed that can be implemented regardless of the uncertainty or linearity of the design parameters and their constraints. Methods such as qualitative reasoning provide an effective and sound technique for solving complex and uncertain scenarios. Uncertainties in engineering designs can be formulated as variables in the application domain and processed by numerical constraint reasoning. This paper describes the theories and algorithms behind a software platform built upon numerical constraint reasoning for engineering applications. The capability of representing design parameters and outcomes in a 2D solution space provides a practical way for engineers to leverage their existing knowledge and experience. The software expresses the results of the analysis in variable ranges and diagrams showing a 2D design space. Qualitative reasoning can assist in the difficult process of making appropriate engineering assumptions and judgments when carrying out complicated analysis procedures. In addition, interval constraint analysis can be used to derive controlling parameters and design space, therefore giving engineers a good overall understanding of a problem when practical experience is not available.     

Artificial neural networks: current status in cardiovascular medicine

Artificial neural networks are a form of artificial computer intelligence that have been the subject of renewed research interest in the last 10 years. Although they have been used extensively for problems in engineering, they have only recently been applied to medical problems, particularly in the fields of radiology, urology, laboratory medicine and cardiology. An artificial neural network is a distributed network of computing elements that is modeled after a biologic neural system and may be implemented as a computer software program. It is capable of identifying relations in input data that are not easily apparent with current common analytic techniques. The functioning artificial neural network's knowledge is built on learning and experience from previous input data. On the basis of this prior knowledge, the artificial neural network can predict relations found in newly presented data sets. In cardiology, artificial neural networks have been successfully applied to problems in the diagnosis and treatment of coronary artery disease and myocardial infarction, in electrocardiographic interpretation and detection of arrhythmias and in image analysis in cardiac radiography and sonography. This report focuses on the current status of artificial neural network technology in cardiovascular medical research.     

Working Group Report 2: In situ caries models, saliva, microbiology, and statistical considerations

We present a case of a single coronary artery where the right coronary artery (RCA) arose from its proximal part. This rare anomaly was detected during elective coronary angiography in a patient with suspected coronary artery disease. The single coronary artery originated from the left sinus of valsalva, giving rise to RCA proximally and distally dividing into left anterior descending (LAD), ramus intermedius and left circumflex (LCX) arteries. The anginal symptoms in this patient was attributed to a significant stenosis at the proximal LAD which was subsequently dilated by coronary angioplasty. To the best of our knowledge, this is the first reported case of angioplasty of LAD in an anomalous single coronary artery.     

Evaluation of myocardial damage using 123I-BMIPP imaging in patients with vasospastic angina

The purpose of this study is to determine whether left ventricular dysfunction following coronary artery spasm by 123I-BMIPP myocardial imaging. To reveal the clinical efficacy of 123I-BMIPP SPECT, 20 patients with vasospastic angina were studied using resting, 3-hour delayed image with 123I-BMIPP and exercise, 3-hour delayed image with 201Tl SPECT. 123I-BMIPP uptake was decreased compared to 201Tl (discordant) in 12 patients (60%) and in 49/100 myocardial segments (49%). The extent and severity score in resting image with 123I-BMIPP were significantly larger than that in delayed image with 201Tl (p < 0.01). In 123I-BMIPP SPECT, the severity score in the latest ischemia were significantly larger than that in others. The incidence of a complete agreement of decreased 123I-BMIPP uptake and coronary artery spasm was significantly higher (75%) than that in 201Tl (28%, p < 0.01). Furthermore, compared to 201Tl uptake, decreased 123I-BMIPP uptake much more corresponded to reduced wall motion in 9 of patients with mismatching. The severity of regional wall motion abnormality was significantly correlated with severity score of 123I-BMIPP. Late redistribution in delayed image with 123I-BMIPP was seen in 6 patients. The regional washout rate and the severity of regional wall motion abnormality in 6 patients was significantly lower than that in others (p < 0.05). Thus, metabolic abnormality assessed by 123I-BMIPP is well associated with left ventricular asynergy and spastic region in patients with vasospastic angina. In conclusion, 123I-BMIPP SPECT may sensitively delineate the impaired myocardium following coronary artery spasm, and it is very useful in diagnosing and estimating the severity of vasospastic angina.