Diagnostic usefulness of the post-exercise systolic blood pressure response for the detection of coronary artery disease in patients with diabetes mellitus

金沢大学大学院医学系研究科Patients with diabetes mellitus (DM) often have a positive result on exercise testing despite a normal coronary arteriogram, which indicates that exercise-induced ST depression is not always an accurate indicator of the presence of coronary artery disease (CAD) in such patients. The present study evaluated the usefulness of the post-exercise systolic blood pressure (SBP) response for the detection of CAD in 47 consecutive patients with DM. Significant stenotic lesions were detected by angiography in 25 patients; 18 of these had true positive (TP) exercise testing results, and 7 had false negative (FN) results. No significant stenotic lesions were detected in the remaining 22 patients and of these 10 had true negative (TN) exercise testing results, and 12 had false positive (FP) results. The SBP ratio (SBP after 3 min of recovery divided by the SBP at peak exercise) was significantly higher in patients with coronary stenoses than in those without. Analysis of the relative cumulative frequency revealed that a SBP ratio greater than 0.87 was associated with significant stenoses. The sensitivity, specificity, and accuracy of ST change combined with a SBP ratio greater than 0.87 for detecting stenoses in patients with DM were 68%, 82%, and 74%, respectively. These results suggest that calculating the SBP ratio, in combination with monitoring for ST depression, improves the accuracy of treadmill exercise testing for the detection of CAD in patients with DM

Evaluation of Simultaneous Dual-radioisotope SPECT Imaging Using 18F-fluorodeoxyglucose and 99mTc-tetrofosmin

Objective(s): Use of a positron emission tomography (PET)/single-photonemission computed tomography (SPECT) system facilitates the simultaneousacquisition of images with fluorine-18 fluorodeoxyglucose (18F-FDG) andtechnetium (99mTc)-tetrofosmin. However, 18F has a short half-life, and 511keV Compton-scattered photons are detected in the 99mTc energy window.Therefore, in this study, we aimed to investigate the consequences of thesefacts.Methods: The crosstalk correction for images in the 99mTc energy windowinvolved the dual energy window (DEW) subtraction method. In phantomstudies, changes in the count of uniform parts in a phantom (due to attenuationfrom decay), signal detectability in the hot-rod part of the phantom, and thedefect contrast ratio in a cardiac phantom were examined.Results: For 18F-FDG in the step-and-shoot mode, nearly a 9% difference wasobserved in the count of projection data between the start and end positionsof acquisition in the uniform part of the phantom. Based on the findings,the detectability of 12 mm hot rods was relatively poor. In the continuousacquisition mode, the count difference was corrected, and detectability of thehot rods was improved. The crosstalk from 18F to the 99mTc energy windowwas approximately 13%. In the cardiac phantom, the defect contrast in 99mTcimages from simultaneous dual-radionuclide acquisition was improved byapproximately 9% after DEW correction; the contrast after correction wassimilar to acquisition with 99mTc alone.Conclusion: Based on the findings, the continuous mode is useful for 18F-FDGacquisition, and DEW crosstalk correction is necessary for 99mTc-tetrofosminimaging

Coronary lesion morphology and prognosis in young males with myocardial infarction with or without familial hypercholesterolemia

金沢大学大学院医学系研究科The present study examined the angiographic characteristics and prognosis of young males under 40 years of age with acute myocardial infarction (AMI) and familial hypercholesterolemia (FH). The study group was divided into an FH group (n = 16) and a non-FH group (n = 27). Lesion morphology was classified as complex or smooth. Overall 36 patients were followed up for an average of 9.4 years. The frequency of angiographic normal or non-obstructive culprit lesions was significantly higher in the non-FH group (p < 0.01). In contrast, the incidence of complex or totally occlusive lesions was higher in the FH group (p < 0.01). At 10-year follow-up, survival rates from cardiac death (FH 85% vs non-FH 100%, p = 0.06), from AMI (FH 43% vs non-FH 80%, p < 0.05), and from any ischemic event at a new lesion (FH 9% vs non-FH 67%, p < 0.01) were all reduced in the FH group. These results suggest that the mechanism of AMI in young male patients with FH differs from that in similar aged patients without FH, and that the overall prognosis of these patients is less favorable

High-Performance Computing Service Over the Internet for Intraoperative Image Processing

Abstract — This paper presents a framework for a cluster system that is suited for high-resolution image processing over the Internet during surgery. The system realizes high performance computing (HPC) assisted surgery, which allows surgeons utilize HPC resources remote from operating room. One application available in the system is an intraoperative estimator for the range of motion (ROM) adjustment in total hip replacement (THR) surgery. In order to perform this compute-intensive estimation during surgery, we parallelize the ROM estimator on a cluster of 64 PCs, each with two CPUs. Acceleration techniques such as dynamic load balancing and data compression methods are incorporated into the system. The system also provides a remote access service over the Internet with a secure execution environment. We applied the system to an actual THR surgery performed at Osaka University Hospital and confirmed that it realizes intraoperative ROM estimation without degrading the resolution of images and limiting the area for estimations. Index Terms — High performance computing, medical image processing, range of motion estimation, computer assisted surgery, cluster computing, message passing program. I