OBJECTIVES The authors used multidetector computed tomography (MDCT) to study the relation between culprit plaque characteristics and cardiac troponin T (cTnT) elevation after percutaneous coronary intervention (PCI). BACKGROUND Percutaneous coronary intervention is often complicated by post-procedural myocardial necrosis manifested by elevated cardiac biomarkers. METHODS Stable angina patients (n = 107) with normal pre-PCI cTnT levels underwent 64-slice MDCT before PCI to evaluate plaque characteristics of culprit lesions. Patients were divided into 2 groups according to presence (group I, n = 36) or absence (group II, n = 71) of post-PCI cTnT elevation ≥3 times the upper limit of normal (0.010 ng/ml) at 24 h after PCI. RESULTS Computed tomography attenuation values were significantly lower in group I than in group II (43.0 [26.5 to 75.7] HU vs. 94.0 [65.0 to 109.0] HU, p < 0.001). Remodeling index was significantly greater in group I than in group II (1.20 ± 0.18 vs. 1.04 ± 0.15, p < 0.001). Spotty calcification was observed significantly more frequently in group I than in group II (50% vs. 11%, p < 0.001). Multivariate analysis showed presence of positive remodeling (remodeling index >1.05; odds ratio: 4.54; 95% confidence interval: 1.36 to 15.9; p = 0.014) and spotty calcification (odds ratio: 4.27; 95% confidence interval: 1.30 to 14.8; p = 0.016) were statistically significant independent predictors for cTnT elevation. For prediction of cTnT elevation, the presence of all 3 variables (CT attenuation value <55 HU; remodeling index >1.05, and spotty calcification) showed a high positive predictive value of 94%, and their absence showed a high negative predictive value of 90%. CONCLUSIONS MDCT may be useful in detecting which lesions are at high risk for myocardial necrosis after PCI.

PURPOSE: We previously reported that hypertension is related to colonic diverticular bleeding, suggesting the involvement of arteriosclerosis. The recurrence of diverticular bleeding has been little investigated. We aimed to elucidate additional risk factors for diverticular bleeding and also to investigate the incidence rates and risk factors for re-bleeding. METHODS: Between January 2006 and September 2010, 62 patients with diverticular bleeding were admitted to our hospital. We then selected 124 control subjects with non-bleeding diverticula from the colonoscopy database of our department. Additionally, a retrospective cohort study was conducted using these case patients to estimate the re-bleeding rate after initial diverticular bleeding and the risk factors for re-bleeding. Odds ratios for diverticular bleeding were calculated by multivariate logistic regression in a case-control study. Cumulative re-bleeding rates since initial bleeding and hazard ratios of risk factors were estimated by Kaplan-Meier method and Cox proportional hazard model. RESULTS: Sixty-two patients presented 99 bleeding episodes including the initial ones. Diabetes mellitus (OR 2.5, 95 % CI 1.2-5.2, P = 0.03), cardio- or cerebrovascular diseases (OR 4.2, 95 % CI 1.7-11.3, P = 0.003), and NSAID use (OR 3.7, 95 % CI 1.3-11.6, P = 0.02) were shown to be independent risk factors. The cumulative re-bleeding rates were 21 %, 34 %, and 40 % at 1, 2, and 3 years, respectively, in which NSAID use (HR 6.3, 95 % CI 1.7-20.7, P = 0.007) was a risk factor for re-bleeding. CONCLUSIONS: Diabetes mellitus and vascular diseases were risk factors for diverticular bleeding, suggesting systemic metabolic disorders and arteriosclerosis might play an important role.

The objective of this study was to evaluate a resolution recovery (RR) method using a variety of simulated human brain [(11)C]raclopride positron emission tomography (PET) images. Simulated datasets of 15 numerical human phantoms were processed by a wavelet-based RR method using an anatomical prior. The anatomical prior was in the form of a hybrid segmented atlas, which combined an atlas for anatomical labelling and a PET image for functional labelling of each anatomical structure. We applied RR to both 60 min static and dynamic PET images. Recovery was quantified in 84 regions, comparing the typical 'true' value for the simulation, as obtained in normal subjects, simulated and RR PET images. The radioactivity concentration in the white matter, striatum and other cortical regions was successfully recovered for the 60 min static image of all 15 human phantoms; the dependence of the solution on accurate anatomical information was demonstrated by the difficulty of the technique to retrieve the subthalamic nuclei due to mismatch between the two atlases used for data simulation and recovery. Structural and functional synergy for resolution recovery (SFS-RR) improved quantification in the caudate and putamen, the main regions of interest, from -30.1% and -26.2% to -17.6% and -15.1%, respectively, for the 60 min static image and from -51.4% and -38.3% to -27.6% and -20.3% for the binding potential (BP(ND)) image, respectively. The proposed methodology proved effective in the RR of small structures from brain [(11)C]raclopride PET images. The improvement is consistent across the anatomical variability of a simulated population as long as accurate anatomical segmentations are provided.

Background/Aims: Capsule endoscopy (CE) has high positive (95%) and negative predictive values (83- 100%) for the bleeding source in patients with obscure gastrointestinal bleeding (OGIB) but the diagnostic yield is influenced by the timing of the examination and the nature of the bleeding. Methodology: We investigated the role of early CE in the diagnosis of patients with overt OGIB. Patients were divided into 4 groups according to the interval between bleeding and CE. The diagnosis rate and clinical outcomes including type of intervention and recurrent bleeding were compared. The association between the timing of CE and small bowel lesions detected by CE was also analysed. Results: Ninety patients with overt OGIB underwent CE. CE revealed the bleeding source in 46 patients (51%). The diagnosis rate was 73%, 48%, 50% and 35% in 1st, 2nd, 3rd and 4th quartiles (p=0.08). The duration between bleeding and CE was shorter for patients with angioectasia than for those with other abnormalities. The proportion of surgeries and endoscopic interventions was significantly higher in 1st and 2nd quartiles than 3rd and 4th quartiles (p=0.048). Conclusions: Earlier timing of CE achieved a higher diagnostic yield for patients with overt OGIB and consequently resulted in a higher intervention rate.

OBJECTIVES This study evaluated the clinical value of myocardial contrast delayed enhancement (DE) with multidetector computed tomography (MDCT) for predicting clinical outcome after acute myocardial infarction (AMI). BACKGROUND Although some studies have described the use of MDCT for assessment of myocardial viability after AMI, clinical experience remains limited. METHODS In 102 patients with first AMI, 64-slice MDCT without iodine reinjection was performed immediately following successful percutaneous coronary intervention (PCI). We measured the size of myocardial contrast DE on MDCT and compared it with clinical outcome. Primary composite cardiac events were cardiac death or hospitalization for worsening heart failure. RESULTS Among the 102 patients (24 ± 10 months follow-up), 19 patients experienced primary composite cardiac events (cardiac death, n = 7; heart failure, n = 12). Kaplan-Meier analysis showed higher risk of cardiac events for patients in the third tertile of myocardial contrast DE size (≥ 36 g) than for those in the other 2 tertiles (p < 0.0001). Multivariable Cox proportional hazards regression analysis indicated that myocardial contrast DE size (adjusted hazard ratio [HR] for tertile 3 vs. 1: 16.1, 95% confidence interval [CI]: 1.45 to 72.4, p = 0.022; HR for tertile 3 vs. 2: 5.06, 95% CI: 1.25 to 22.7, p = 0.039) was a significant independent predictor for cardiac events after adjustment for Thrombolysis In Myocardial Infarction risk score, left ventricular ejection fraction, total defect score on single-photon emission CT with technetium tetrofosmin, and transmural extent of myocardial contrast DE on MDCT. CONCLUSIONS Myocardial contrast DE size on MDCT immediately after primary PCI may provide promising information for predicting clinical outcome in patients with AMI.

PURPOSE In small animal imaging using a single photon emitting radionuclide, a high resolution gamma camera is required. Recently, position sensitive photomultiplier tubes (PSPMTs) with high quantum efficiency have been developed. By combining these with nonhygroscopic scintillators with a relatively low light output, a high resolution gamma camera can become useful for low energy gamma photons. Therefore, the authors developed a gamma camera by combining a pixelated Ce-doped Gd(2)SiO(5)(GSO) block with a high quantum efficiency PSPMT. METHODS GSO was selected for the scintillator, because it is not hygroscopic and does not contain any natural radioactivity. An array of 1.9 mm × 1.9 mm × 7 mm individual GSO crystal elements was constructed. These GSOs were combined with a 0.1-mm thick reflector to form a 22 × 22 matrix and optically coupled to a high quantum efficiency PSPMT (H8500C-100 MOD8). The GSO gamma camera was encased in a tungsten gamma-ray shield with tungsten pixelated parallel hole collimator, and the basic performance was measured for Co-57 gamma photons (122 keV). RESULTS In a two-dimensional position histogram, all pixels were clearly resolved. The energy resolution was ∼15% FWHM. With the 20-mm thick tungsten pixelated collimator, the spatial resolution was 4.4-mm FWHM 40 mm from the collimator surface, and the sensitivity was ∼0.05%. Phantom and small animal images were successfully obtained with our developed gamma camera. CONCLUSIONS These results confirmed that the developed pixelated GSO gamma camera has potential as an effective instrument for low energy gamma photon imaging.

BACKGROUND: Patient movement has been considered an important source of errors in cardiac PET. This study was aimed at evaluating the effects of such movement on myocardial blood flow (MBF) and perfusable tissue fraction (PTF) measurements in intravenous (15)O-water PET. METHODS: Nineteen (15)O-water scans were performed on ten healthy volunteers and three patients with severe cardiac dysfunction under resting conditions. Motions of subjects during scans were estimated by monitoring locations of markers on their chests using an optical motion-tracking device. Each sinogram of the dynamic emission frames was corrected for subject motion. Variation of regional MBF and PTF with and without the motion corrections was evaluated. RESULTS: In nine scans, motions during (15)O-water scan (inter-frame (IF) motion) and misalignments relative to the transmission scan (inter-scan (IS) motion) larger than the spatial resolution of the PET scanner (4.0 mm) were both detected by the optical motion-tracking device. After correction for IF motions, MBF values changed from 0.845 ± 0.366 to 0.780 ± 0.360 mL/minute/g (P < .05). In four scans with only IS motion detected, PTF values changed significantly from 0.465 ± 0.118 to 0.504 ± 0.087 g/mL (P< .05), but no significant change was found in MBF values. CONCLUSIONS: This study demonstrates that IF motion during (15)O-water scan at rest can be source of error in MBF measurement. Furthermore, estimated MBF is less sensitive than PTF values to misalignment between transmission and (15)O-water emission scans.

INTRODUCTION: Measurement of regional cerebral blood flow (rCBF) in rodents can provide knowledge of pathophysiology of the cerebral circulation, but generally requires blood sampling for analysis during positron emission tomography (PET). We therefore tested the feasibility of using an arteriovenous (AV) shunt in rats for less invasive blood analysis. METHODS: Six anesthetized rats received [(15)O]H(2)O and [(15)O]CO PET scans with their femoral artery and vein connected by an AV shunt, the activity within which was measured with a germanium ortho-oxysilicate scintillation detector. The [(15)O]H(2)O was intravenously injected either at a faster or slower injection rate, while animals were placed either with their head or heart centered in the gantry. The time-activity curve (TAC) from the AV shunt was compared with that from the cardiac ventricle in PET image. The rCBF values were calculated by a nonlinear least-square method using the dispersion-corrected AV-shunt TAC as an input. RESULTS: The AV-shunt TAC had higher signal-to-noise ratio, but also had delay and dispersion compared with the image-derived TAC. The delay time between the AV-shunt TAC and image-based TAC ranged from 11 to 21 s, while the dispersion was estimated to be ∼5 s as a time constant of the dispersion model of exponential function, and both were properly corrected. In a steady-state condition of [(15)O]CO PET, the blood activity concentration by AV-shunt TAC was also comparable in height with the image-based TAC corrected for partial volume. Whole-brain CBF values measured by [(15)O]H(2)O were 0.37±0.04 (mean±S.D.) ml/g/min, partition coefficient was 0.73±0.04 ml/g, and the CBF varied in a linear relationship with partial pressure of carbon dioxide during each scan. CONCLUSIONS: The AV-shunt technique allows less invasive, quantitative and reproducible measurement of rCBF in [(15)O]H(2)O PET studies in rats than direct blood sampling and radioassay.

Objectives: The aim of this study was to evaluate whether combination therapy of clopidogrel and proton pump inhibitors (PPIs) causes higher numbers of cardiovascular events than clopidogrel alone in Japanese patients. Background: PPIs are often prescribed in combination with clopidogrel following coronary stenting. PPIs are reported to diminish the effect of clopidogrel because both are metabolized by CYP2C19. However, no reports address the effects of PPIs on cardiovascular events following coronary stenting in the Japanese population. Methods: A total of 1,887 patients treated with clopidogrel following coronary stenting were enrolled in the Ibaraki Cardiac Assessment Study (ICAS) registry. All subjects were classified into two groups according to treatment without (n = 819) or with (n = 1,068) PPI. Propensity score analysis matched 1:1 according to treatment without PPI (n = 500) or with PPI (n = 500). Primary endpoint was the composite of all-cause death or myocardial infarction. Results: No significant difference was observed in the primary endpoint between the group without PPI and the group with PPI (4.6% vs. 4.6%, P = 0.77). In contrast, a significant difference was found between the group without PPI and with PPI in regard to the incidence of gastrointestinal bleeding at the end of the follow-up period and the specific PPI prescribed (2.4% vs. 0.8%, adjusted HR = 0.30, 95% Confidence interval 0.08-0.87, P = 0.026) after propensity score matching. Conclusions: No significant association between PPI use and primary endpoint was observed in the Japanese population, whereas PPI use resulted in a significant reduction in the rate of gastrointestinal bleeding. © 2012 Wiley Periodicals, Inc.