Consistency of dose rates after applying machine-specific reference correction factors for the gamma knife 16 mm collimator field.

BACKGROUND: The machine-specific reference (msr) correction factors ( k Q msr , Q 0 f msr , f ref $k_{{Q_{{\rm{msr}}}},\;{Q_0}}^{{f_{{\rm{msr}}}},{f_{{\rm{ref}}}}}$ ) were introduced in International Atomic Energy Agency (IAEA) Technical Report Series 483 (TRS-483) for reference dosimetry of small fields. Several correction factor sets exist for a Leksell Gamma Knife (GK) Perfexion or Icon. Nevertheless, experiments have not rigorously validated the correction factors from different studies. PURPOSE: This study aimed to assess the role and accuracy of k Q msr , Q 0 f msr , f ref $k_{{Q_{{\rm{msr}}}},\;{Q_0}}^{{f_{{\rm{msr}}}},{f_{{\rm{ref}}}}}$ values in determining the absorbed dose rates to water in the reference dosimetry of Gamma Knife. METHODS: The dose rates in the 16 mm collimator field of a GK were determined following the international code of practices with three ionization chambers: PTW T31010, PTW T31016 (PTW Freiberg GmbH, New York, NY), and Exradin A16 (Standard Imaging, Inc., Middleton, WI). A chamber was placed at the center of a solid water phantom (Elekta AB, Stockholm, Sweden) using a detector-specific insert. The reference point of the ionization chamber was confirmed using cone-beam CT images. Consistency checks were repeated five times at a GK site and performed once at seven GK sites. Correction factors from six simulations reported in previous studies were employed. Variations in the dose rates and relative dose rates before and after applying the k Q m s r , Q 0 f m s r , f r e f $k_{{Q_{msr}},\;{Q_0}}^{{f_{msr}},{f_{ref}}}$ were statistically compared. RESULTS: The standard deviation of the dose rates measured by the three chambers decreased significantly after any correction method was applied (p = 0.000). When the correction factors of all studies were averaged, the standard deviation was reduced significantly more than when any single correction method was applied (p ≤ 0.030), except for the IAEA TRS-483 correction factors (p = 0.148). Before any correction was applied, there were statistically significant differences among the relative dose rates measured by the three chambers (p = 0.000). None of the single correction methods could remove the differences among the ionization chambers (p ≤ 0.038). After TRS-483 correction, the dose rate of Exradin A16 differed from those of the other two chambers (p ≤ 0.025). After the averaged factors were applied, there were no statistically significant differences between any pairs of chambers according to Scheffe's post hoc analyses (p ≥ 0.051); however, PTW T31010 differed from PTW 31016 according to Tukey's HSD analyses (p = 0.040). CONCLUSION: The k Q msr , Q 0 f msr , f ref $k_{{Q_{{\rm{msr}}}},\;{Q_0}}^{{f_{{\rm{msr}}}},{f_{{\rm{ref}}}}}$ significantly reduced variations in the dose rates measured by the three ionization chambers. The mean correction factors of the six simulations produced the most consistent results, but this finding was not explicitly proven in the statistical analyses.

Incidence and clinical impact of early recurrence of atrial tachyarrhythmia after surgical ablation for atrial fibrillation.

BACKGROUND: Atrial tachyarrhythmias (ATAs) are common within the 3-month blanking period after catheter ablation of atrial fibrillation (AF). However, little evidence is available regarding the current guidelines on the blanking period after surgical AF ablation. We investigate the incidence and significance of early recurrence of atrial tachyarrhythmia (ERAT) and evaluate the optimal blanking period after surgical AF ablation. METHODS: Data from 259 patients who underwent surgical AF ablation from 2009 to 2016 were collected. ERAT was defined as documented ATA episodes lasting for 30 s. A multivariate Cox proportional hazard model was constructed to evaluate the role of ERAT as a predictor of late recurrences (LR) for AF. RESULTS: In total, 127 patients (49.0%) experienced their last episodes of ERAT during the first (n = 65), second (n = 14), or third (n = 48) month of the 3-month blanking period (p < .001). One year freedom from ATAs was 97.8% in patients without ERAT compared with 95.4%, 64.3%, and 8.3% in patients with ERAT in the first, second, and third months after the index procedure, respectively (p < .001). Hazard ratios of LR according to the timing of the last episode of ERAT first, second, and third months after the procedure were 2.84, 16.70, and 119.75, respectively. CONCLUSIONS: The ERAT occurred in 49.0% of patients within the first 3 months after surgical ablation. The occurrence of ERAT within 3 months after surgical AF ablation was a significant independent predictor of LR. Hence, the currently accepted 3-month blanking period may be considered for redefining in patients with AF surgical ablation.

Value of Coronary Angiography in the Cardiac Myxoma.

Preoperative coronary angiography for cardiac myxoma not only excludes coronary artery disease but also detects the artery feeding the cardiac myxoma, which has several clinical implications. In this study, we examined cardiac myxoma cases in two tertiary hospitals using coronary angiography to identify the artery feeding the myxoma. We retrospectively reviewed 42 patients with cardiac myxoma who had undergone surgical removal between July 2008 and December 2015 in two tertiary hospitals, and recorded their baseline characteristics, echocardiographic findings, and coronary angiography. Among those 42 patients, 23 (55%) had coronary angiography before surgery and in no case was significant luminal narrowing observed. In 21 of the coronary angiograms, the artery feeding the cardiac myxoma had a vascular branch (100%), clusters of tortuous vessels with contrast medium pooling (67%), an arteriocavity fistula (33%), and a mobile feeding artery (67%). No significant relationship was found between coronary artery dominance type and the origin of the artery feeding the cardiac myxoma (P = 0.362). Identification of the artery feeding the cardiac myxoma, with a distinctive vascular appearance in coronary angiography, is important for several clinical applications such as helping to diagnose cardiac myxoma and to plan the surgical approach. Clin. Anat. 33:833-838, 2020. © 2019 Wiley Periodicals, Inc.

Development of an IAEA phase-space dataset for the Leksell Gamma Knife® Perfexion™ using multi-threaded Geant4 simulations.

This study was conducted to develop a phase-space dataset in the International Atomic Energy Agency (IAEA) format for Monte Carlo (MC) simulations of the Leksell Gamma Knife® (LGK, Elekta Instrument AB, Stockholm, Sweden) Perfexion™ (PFX). An open-source MC code, namely, the Geant4 toolkit with a recently updated multi-threaded mode, was used to maximize the efficiency of the developed IAEA phase-space dataset. The absorbed dose profiles for single shots of the LGK PFX were calculated using the developed dataset and compared with those from radiochromic film measurements and Leksell GammaPlan® version 11.0.3 (LGP, Elekta Instruments) for verification. The mean relative absorbed dose differences in all single shots were less than 3.6% compared with the films and less than 4.0% compared with LGP. The collimator output factors were also calculated for all single shots and compared with the LGP results. The simulated collimator output factor was 0.816 ±â€¯0.003 for a 4-mm shot and 0.903 ±â€¯0.001 for an 8-mm shot in a spherical water phantom. The efficiency of the developed dataset was evaluated by comparing the times required for various simulations. Simulations with the phase-space dataset ran 25, 8.2 and 3.2 times faster than simulations without the phase-space dataset for 4-, 8-, and 16-mm shots, respectively. Using the dataset developed in this study, MC simulations of the LGK PFX can be performed more efficiently for various purposes, such as treatment plan verification and beam quality factor calculations.

Development of a PMMA phantom as a practical alternative for quality control of gamma knife® dosimetry.

BACKGROUND: To measure the absorbed dose rate to water and penumbra of a Gamma Knife® (GK) using a polymethyl metacrylate (PMMA) phantom. METHODS: A multi-purpose PMMA phantom was developed to measure the absorbed dose rate to water and the dose distribution of a GK. The phantom consists of a hemispherical outer phantom, one exchangeable cylindrical chamber-hosting inner phantom, and two film-hosting inner phantoms. The radius of the phantom was determined considering the electron density of the PMMA such that it corresponds to 8 g/cm2 water depth, which is the reference depth of the absorbed dose measurement of GK. The absorbed dose rate to water was measured with a PTW TN31010 chamber, and the dose distributions were measured with radiochromic films at the calibration center of a patient positioning system of a GK Perfexion. A spherical water-filled phantom with the same water equivalent depth was constructed as a reference phantom. The dose rate to water and dose distributions at the center of a circular field delimited by a 16-mm collimator were measured with the PMMA phantom at six GK Perfexion sites. RESULTS: The radius of the PMMA phantom was determined to be 6.93 cm, corresponding to equivalent water depth of 8 g/cm2. The absorbed dose rate to water was measured with the PMMA phantom, the spherical water-filled phantom and a commercial solid water phantom. The measured dose rate with the PMMA phantom was 1.2% and 1.8% higher than those measured with the spherical water-filled phantom and the solid water phantom, respectively. These differences can be explained by the scattered photon contribution of PMMA off incoming 60Co gamma-rays to the dose rate. The average full width half maximum and penumbra values measured with the PMMA phantom showed reasonable agreement with two calculated values, one at the center of the PMMA phantom (LGP6.93) and other at the center of a water sphere with a radius of 8 cm (LGP8.0) given by Leksell Gamma Plan using the TMR10 algorithm. CONCLUSIONS: A PMMA phantom constructed in this study to measure the absorbed dose rates to water and dose distributions of a GK represents an acceptable and practical alternative for GK dosimetry considering its cost-effectiveness and ease of handling.

Assessment of the accuracy and stability of frameless gamma knife radiosurgery.

The aim of this study was to assess the accuracy and stability of frameless gamma knife radiosurgery (GKRS). The accuracies of the radiation isocenter and patient couch movement were evaluated by film dosimetry with a half-year cycle. Radiation isocenter assessment with a diode detector and cone-beam computed tomography (CBCT) image accuracy tests were performed daily with a vendor-provided tool for one and a half years after installation. CBCT image quality was examined twice a month with a phantom. The accuracy of image coregistration using CBCT images was studied using magnetic resonance (MR) and computed tomography (CT) images of another phantom. The overall positional accuracy was measured in whole procedure tests using film dosimetry with an anthropomorphic phantom. The positional errors of the radiation isocenter at the center and at an extreme position were both less than 0.1 mm. The three-dimensional deviation of the CBCT coordinate system was stable for one and a half years (mean 0.04 ± 0.02 mm). Image coregistration revealed a difference of 0.2 ± 0.1 mm between CT and CBCT images and a deviation of 0.4 ± 0.2 mm between MR and CBCT images. The whole procedure test of the positional accuracy of the mask-based irradiation revealed an accuracy of 0.5 ± 0.6 mm. The radiation isocenter accuracy, patient couch movement accuracy, and Gamma Knife Icon CBCT accuracy were all approximately 0.1 mm and were stable for one and a half years. The coordinate system assigned to MR images through coregistration was more accurate than the system defined by fiducial markers. Possible patient motion during irradiation should be considered when evaluating the overall accuracy of frameless GKRS.

Assessment of image co-registration accuracy for frameless gamma knife surgery.

Image co-registration is used in frameless gamma knife radiosurgery (GKSRS) to assign a stereotactic coordinate system and verify patient setup before irradiation. The accuracy of co-registration with cone beam computed tomography (CBCT) images of a Gamma Knife IconTM (GK Icon) was assessed, and the effects of the region of co-registration (ROC) were studied. CBCT-to-CBCT co-registration is used for patient setup verification, and its accuracy was examined by co-registering CBCT images taken at various configurations with a reference CBCT series. The accuracy of stereotactic coordinate assignment was investigated by co-registering stereotactic CT images with CBCT images taken at various configurations. An anthropomorphic phantom was used, and the coordinates of fifteen landmarks inside the phantom were measured. The co-registration accuracy between stereotactic magnetic resonance (MR) and CBCT images was evaluated using images from forty-one patients. The positions of the anterior and posterior commissures were measured in both a fiducial marker-based system and a co-registered system. To assess the effects of MR image distortions, co-registration was performed with four different ranges, and the accuracy of the results was compared. Co-registration between CBCT images gave a mean three-dimensional deviation of 0.2 ± 0.1 mm. The co-registration of stereotactic CT images with CBCT images produced a mean deviation of 0.5 ± 0.2 mm. The co-registration of MR images with CBCT images resulted in the smallest three-dimensional difference (0.8 ± 0.3 mm) when a co-registration region covering the skull base area was applied. The image co-registration errors in frameless GKSRS were similar to the imaging errors of frame-based GKSRS. The lower portion of the patient's head, including the base of the skull, is recommended for the ROC.

Radiation reduction during percutaneous coronary intervention: A new protocol with a low frame rate and selective fluoroscopic image storage.

The percutaneous coronary intervention (PCI) procedure is associated with potentially high levels of radiation exposure and therefore increased risk of adverse radiation-induced outcomes, ranging from cataract to malignancy. Frame rate reduction and selective fluoroscopy storage may help reduce radiation exposure. In this study, we evaluated the efficacy of a radiation reduction protocol that uses a lower frame rate and selective storage of fluoroscopic images in terms of its effect on reducing the radiation dose during PCI.The new protocol incorporated a lower frame rate as compared with the conventional protocol, and used selective storage of fluoroscopic images. We reviewed the medical records of patients who underwent PCI under the conventional protocol from January 2013 to December 2013, and compared them with those who underwent PCI with the new protocol from January 2015 to December 2015. The primary endpoint was radiation dose reduction expressed as cumulative air kerma and dose-area product (DAP). The image quality was assessed by 3 independent well-trained cardiologists.One hundred fifty-five patients were enrolled in the conventional protocol group, and 152 were enrolled in the radiation reduction protocol group (total, n = 307). There was no statistical significance in terms of the baseline characteristics, including body mass index. Overall, the radiation reduction protocol group showed a significant reduction in both cumulative air kerma (1634.39 ±â€Š717.95 vs 2074.75 ±â€Š1003.72 mGy, P < .001) and DAP (12344.86 ±â€Š5371.75 vs 15312.19 ±â€Š7136.58 µGy m, P < .001). Image quality was acceptable in both groups.The radiation reduction protocol, which uses a lower frame rate and selective storage of fluoroscopic images, may be an alternative approach to reducing PCI radiation dose.

Verification of dose profiles generated by the convolution algorithm of the gamma knife® radiosurgery planning system.

PURPOSE: A convolution algorithm that takes into account electron-density inhomogeneity was recently introduced to calculate dose distributions for the Gamma Knife (GK) Perfexion™ treatment planning program. The accuracies of the dose distributions computed using the convolution method were assessed using an anthropomorphic phantom and film dosimetry. METHODS: Absorbed-dose distributions inside a phantom (CIRS Radiosurgery Head Phantom, Model 605) were calculated using the convolution method of the GK treatment-planning software (Leksell Gamma Plan® version 10.1; LGP) for various combinations of collimator size, location, direction of calculation plane, and number of shots. Computed tomography (CT) images of the phantom and a data set of CT number versus electron density were provided to the LGP. Calculated distributions were exported as digital-image communications in medicine-radiation therapy (DICOM-RT) files. Three types of radiochromic film (GafChromic® MD-V2-55, MD-V3, and EBT2) were irradiated inside the phantom using GK Perfexion™. Scanned images of the measured films were processed following standard radiochromic film-handling procedures. For a two-dimensional quantitative evaluation, gamma index pass rates (GIPRs) and normalized agreement-test indices (NATIs) were obtained. Image handling and index calculations were performed using a commercial software package (DoseLab Pro version 6.80). RESULTS: The film-dose calibration data were well fitted with third-order polynomials (R2  ≥ 0.9993). The mean GIPR and NATI of the 93 analyzed films were 99.3 ± 1.1% and 0.8 ± 1.3, respectively, using 3%/1.0 mm criteria. The calculated maximum doses were 4.3 ± 1.7% higher than the measured values for the 4 mm single shots and 1.8 ± 0.7% greater than those for the 8 mm single shots, whereas differences of only 0.3 ± 0.9% were observed for the 16 mm single shots. The accuracy of the calculated distribution was not statistically related to the collimator size, number of shots, or centrality of location (P > 0.05, independent-sample t-test). The plans in the axial planes exhibited poorer agreement with the measured distributions than the plans in the coronal or sagittal planes; however, their GIPR values (≥ 96.9%) were clinically acceptable. The plans for an arbitrary virtual target of volume 1.6 cm3 at an axial plane close to the top of the phantom showed the worst agreement and the greatest fluctuation (GIPR = 96.9 ± 1.2%, NATI = 3.9 ± 1.7). CONCLUSIONS: The measured accuracies of the dose distributions calculated by the convolution algorithm of the LGP were within the clinically acceptable range (GIPR ≥ 96.9%) for various configurations of collimator size, location, direction of calculation plane, and number of shots. Due to the intrinsic asymmetry in the dose distribution along the z-axis, the treatment plan should also be verified in coronal or sagittal plane.

An effective calibration technique for radiochromic films using a single-shot dose distribution in Gamma Knife(®).

PURPOSE: A method of calibrating radiochromic films for Gamma Knife(®) (GK) dosimetry was developed. The applicability and accuracy of the new method were examined. METHODS: The dose distribution for a sixteen millimeter single-shot from a GK was built using a reference film that was calibrated using the conventional multi-film calibration (MFC) method. Another film, the test film, from a different set of films was irradiated under the same conditions as the reference film. The calibration curve for the second set of films was obtained by assigning the dose distribution of the reference film to the optical density of the test film, point by point. To assess the accuracy of this single-film calibration (SFC) method, differences between gamma index pass rates (GIPRs) were calculated. RESULTS: The SFC curves were successfully obtained with estimated errors of 1.46%. GIPRs obtained with the SFC method for films irradiated using a single-shot showed differences less than one percentage point when dose difference criterion (ΔD) was 2% and the distance to agreement criterion (Δd) was 1 mm. The GIPRs of the SFC method when the films were irradiated following a virtual target treatment plan were consistent with the GIPRs of the MFC method, with differences of less than 0.2 percentage points for ΔD = 1% and Δd = 1 mm. CONCLUSION: The accuracy of the SFC method is comparable to that of conventional multi-film calibration method for GK film dosimetry.

Antiplatelet effect of ticagrelor compared to tirofiban in non-ST-segment elevation ACS patients undergoing PCI. The result of the TE-CLOT trial.

Addition of a potent P2Y12 inhibitor to aspirin is the standard therapy for non-ST-segment elevation acute coronary syndrome (NSTE-ACS) patients undergoing percutaneous coronary intervention (PCI). Glycoprotein IIb/IIIa inhibitor, together with antiplatelet therapy, may be considered as part of initial therapy in NSTE-ACS patients with high-risk features. This study investigated the antiplatelet effect of ticagrelor loading dose (LD) versus tirofiban bolus injection with a post-bolus infusion on top of aspirin among NSTE-ACS patients planned to PCI. NSTE-ACS patients were randomised to receive either ticagrelor (n = 47) or tirofiban (n = 48). Platelet reactivity was assessed by light transmittance aggregometry at 0, 2, 8, and 24 hours (h) after treatment initiation. Primary endpoint was inhibition of platelet aggregation (IPA, 20 µM ADP, final extent) at 2 h after LD therapy, with a non-inferiority margin of 10%. The prevalence of high on-treatment platelet reactivity (HPR) was also compared at 0, 2, 8, and 24 h. The mean difference in IPA between ticagrelor and tirofiban was -9.9% (95% confidence interval: -25.7% to 5.9%) at 2 h, -1.6% (-8.0% to 4.8%) at 8 h, and -3.3% (-18.4% to 12.0%) at 24 h. The prevalence of HPR did not differ between the two groups at any time point (all p values ≥ 0.059), which was almost abolished by 8 h post-LD (< 5%). In conclusion, the antiplatelet effect during the early phase (~2 h) after ticagrelor LD appeared to be relatively strong, but it did not reach that of tirofiban in NSTE-ACS patients.

Radiation Exposure in Coronary Angiography: A Comparison of Cineangiography and Fluorography.

BACKGROUND AND OBJECTIVES: Coronary angiography (CAG) is the gold standard for diagnosing coronary artery disease. However, exposure to ionizing radiation delivered during CAG has various negative biological effects on humans. In this study, there was an evaluation of whether fluorography resulted in decreased radiation exposure, as compared with cineangiography. SUBJECTS AND METHODS: Fifty-five patients were prospectively enrolled and divided into two CAG groups, in accordance with the operator's professional discretion: a conventional cineangiography group versus a fluorography group. Fluorography refers to the photography of fluoroscopic images that are retrospectively stored, e.g., using the "Store fluoro" function of the Siemens cardiac angiography system. The primary outcomes included the air kinetic energy released per unit mass {air kerma (AK) mGy} and the dose (kerma)-area product (DAP; µGy · m(2)), both measured using built-in software in the Siemens system. The secondary outcomes included the total procedure time and amount of contrast agent used with each CAG method. RESULTS: The total AK and DAP were significantly lower in the fluorography group (159.3±64.9 mGy and 1337.9±629.6 µGy · m(2), respectively) than in the cineangiography group (326.9±107.5 mGy and 2341.1±849.9 µGy · m(2), respectively; p=0.000 for both). The total procedure time (cineangiography vs. fluorography, 12.8±4.7 vs. 12.5±2.9 min; p=0.779) and contrast agent amount (136.1±28.3 vs. 126.3±25.7, p=0.214) were comparable between the two groups. CONCLUSION: Fluorography is a useful method to decrease the radiation exposure in selected patients requiring CAG.

Life-threatening cardiac tamponade: a rare complication of acupuncture.

Acupuncture as an ancient Chinese treatment has proven effective and is utilized worldwide. Although it is generally believed to be a safe clinical procedure, serious lethal complications including death have been reported. We present a rare case of life-threatening cardiac tamponade due to penetration of an acupuncture needle directly into the right ventricle.

Effects of trimetazidine in patients with acute myocardial infarction: data from the Korean Acute Myocardial Infarction Registry.

BACKGROUND: Excess myocardial fatty acid oxidation can cause a range of deleterious myocardial effects. Trimetazidine (TMZ) is a clinically effective antianginal agent that selectively inhibits long-chain 3-ketoacyl CoA thiolase, reducing fatty acid oxidation and stimulating glucose oxidation. The role of TMZ in acute myocardial infarction (AMI), however, remains unclear. Our retrospective analysis explores the effect on clinical outcomes of adding TMZ to standard treatment in patients with AMI. METHODS: All 13,733 AMI patients registered in the Korean Acute Myocardial Infarction Registry from 2005 to 2008 were retrospectively enrolled. Patients were divided into two groups: those treated with TMZ during their in-hospital management period and those who were not. Primary endpoints were all-cause death combined in-hospital and 12-month death and major adverse cardiac events (MACE), which included all-cause death, recurrent myocardial infarction (MI), repeated percutaneous coronary intervention (PCI) for target lesion revascularization (TLR), and coronary artery bypass graft. Propensity-matched patients were analyzed using an adjusted Cox proportional hazards model. RESULTS: Baseline clinical and angiographic characteristics in the TMZ and no-TMZ groups were generally similar, with the exceptions of pre-PCI thrombolysis in myocardial infarction flow grade, stent type, and stent length. Over 12 months, the relative risk of all-cause death fell by 59 % (event rate 2.3 vs. 6.4 %; hazard ratio 0.41, 95 % CI 0.18-0.97, P = 0.042) and the relative risk of MACE fell by 76 % (event rate 2.3 vs. 9.5 %; hazard ratio 0.24, 95 % CI 0.10-0.56, P = 0.001) in the TMZ group compared with those in the no-TMZ group. CONCLUSIONS: Trimetazidine appeared to improve clinical outcomes in AMI patients by significantly reducing all-cause mortality and MACE over 12 months.

Adenosine-stress low-dose single-scan CT myocardial perfusion imaging using a 128-slice dual-source CT: a comparison with fractional flow reserve.

BACKGROUND: Coronary CT angiography (CCTA) allows accurate evaluation of coronary artery stenosis but has limitations in information on hemodynamic significance of stenotic lesions. PURPOSE: To determine the feasibility of adenosine-stress low-dose single-scan CT myocardial perfusion imaging (MPI) using a 128-slice dual-source CT scanner for the diagnosis of hemodynamically significant coronary artery stenosis as defined by fractional flow reserve (FFR). MATERIAL AND METHODS: This study was proved by the Institutional Review Board and informed consent was obtained from the patients before enrollment in the study. Ninety-seven patients with chest pain and low-to-intermediate pretest probability of coronary artery disease were prospectively enrolled. Adenosine-stress CCTA using ECG-correlated maximum tube current modulation (Mindose(®)) with 128-slice dual-source CT was performed in all 97 patients. In 37 patients (38.1%; 28 men, nine women; mean age, 61.7 ± 20.5 years; mean heart rate, 74.6 ± 2.8 bpm) with significant stenosis at CCTA (lumen diameter reduction >50%), FFR was performed after CCTA, as a reference standard for the evaluation of myocardial perfusion. FFR value ≤0.75 was considered as positive. CTMPI and CCTA were read by two experienced radiologists with consensus, respectively. RESULTS: The effective radiation dose of adenosine-stress single-scan CTMPI was 4.63 ± 2.57 mSv. Compared with FFR, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying significant coronary stenoses were 93.1%, 82.7%, 75.0%, and 95.6%, respectively, on CCTA and 93.1%, 90.3%, 84.4%, and 95.9%, respectively, on CTMPI. On combined CCTA and CTMPI, sensitivity, specificity, PPV, and NPV were 93.1%, 94.2%, 90.0%, and 96.0%, respectively. CONCLUSION: Adenosine-stress low-dose single scan CTMPI using a 128-slice dual-source CT can provide complementary information on the hemodynamical significance of coronary artery stenosis as well as anatomical information of coronary arteries.

Efficacy of cilostazol on uncontrolled coronary vasospastic angina: a pilot study.

BACKGROUND: Although an angina attack by vasospastic angina (VSA) can usually be relieved or controlled with nitrates and calcium channel blockers (CCBs), there are some patients who cannot be controlled even by higher doses and combinations of these drugs. Cilostazol is a selective inhibitor of phosphodiesterase 3 that increases intracellular cyclic adenosine monophosphate (cAMP) contents. A stimulation of cAMP signal transduction increases coronary nitric oxide production. We examined whether cilostazol improved angina symptoms in patients with VSA uncontrolled by conventional treatment. METHODS: This study was conducted in a prospective, multicenter, nonrandomized manner. The subject consisted of 21 patients (13 men, 57 ± 9 year-old) who were diagnosed with VSA and had at least two angina attacks during the past 1 week despite of conventional medications such as CCBs and/or nitrates. They took cilostazol 100 mg twice daily for 2 weeks in addition to the conventional medications. The patients recorded the frequency of angina attack and wrote down the numeric rating scale of a "severity of angina attack" while taking conventional medications and cilostazol for 2 weeks, and also recorded an averaged scale or total number of event during the last week at the time of the assessment. Using the Wilcoxon rank-sum test, we compared the changes in the scores of frequency and severity of angina attack before and after adding cilostazol to the conventional medications. RESULTS: After adding cilostazol to the conventional medications, there were 78.9% relative reduction of the score of angina intensity and 73.5% of angina frequency (P < 0.001). There were four patients (19%) who were forced to stop cilostazol due to headache as an adverse event. CONCLUSIONS: Cilostazol appears to be an effective therapy in VSA uncontrolled with conventional medical treatment. A further prospective, randomized, placebo-controlled study will be needed to validate this result.

Polyphenol (-)-epigallocatechin gallate-induced cardioprotection may attenuate ischemia-reperfusion injury through adenosine receptor activation: a preliminary study.

BACKGROUND: The activation of guanine nucleotide binding protein-coupled receptors, such as adenosine receptor (ADR) and opioid receptor (OPR), protects the heart against ischemia and reperfusion injury. We hypothesized that ADR or OPR might be involved in polyphenol (-)-epigallocatechin gallate (EGCG)-induced cardioprotection. METHODS: Langendorff perfused rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Hearts were treated with 10 µM of EGCG, with or without the ADR or OPR antagonist at early reperfusion. Infarct size measured with 2,3,5-triphenyltetrazolium chloride staining was chosen as end-point. RESULTS: EGCG significantly reduced infarct volume as a percentage of ischemic volume (33.5 ± 4.1%) compared to control hearts (14.4 ± 1.1%, P < 0.001). A nonspecific ADR antagonist 8-(p-sulfophenyl) theophylline hydrate (27.1 ± 1.9%, P < 0.05 vs. EGCG) but not a nonspecific OPR antagonist naloxone (14.3 ± 1.3%, P > 0.05 vs. EGCG) blocked the anti-infarct effect by EGCG. The infarct reducing effect of EGCG was significantly reversed by 200 nM of the A(1) ADR antagonist DPCPX (25.9 ± 1.1%, P < 0.05) and 15 nM of the A(2B) ADR antagonist MRS1706 (29.3 ± 1.7%, P < 0.01) but not by 10 µM of the A(2A) ADR antagonist ZM241385 (23.9 ± 1.9%. P > 0.05 vs. EGCG) and 100 nM of the A(3) ADR antagonist MRS1334 (24.1 ± 1.8%, P > 0.05). CONCLUSIONS: The infarct reducing effect of EGCG appears to involve activation of ADR, especially A(1) and A(2B) ADR, but not OPR.

Pressure-wire based assessment of microvascular resistance using calibrated upstream balloon obstruction: a predictor of myocardial viability.

OBJECTIVES: We assess microvascular integrity as a marker of myocardial viability after coronary stenting, using only a pressure guidewire. BACKGROUND: Microvascular integrity generally is not assessed using pressure-only guidewires because the transducer lies upstream of microvasculature. We partially inflate a balloon inside a coronary stent to achieve a specific normalized pressure drop at rest (distal coronary/aortic pressure = 0.8) and then infuse a vasodilator, to render the wire sensitive to microvascular function. We hypothesize that the further decline in pressure (ΔFFR(0.8) ) predicts MRI myocardial viability. METHODS: We studied 29 subjects with acute coronary syndrome including myocardial infarction. After successful culprit stenting, the resting coronary/aortic pressure was set to 0.8 using temporary balloon obstruction. ΔFFR(0.8) was defined as 0.8-(distal coronary/aortic pressures) during adenosine-induced hyperemia. The average transmural extent of infarction was defined as the average area of MRI late gadolinium enhancement (after 2.8 ± 1.5 days) divided by the corresponding full thickness of the gadolinium enhanced sector in short axis slices, and was compared with ΔFFR(0.8) . RESULTS: ΔFFR(0.8) corresponded inversely and linearly with the average transmural extent of infarction (r(2) = 0.65, P < 0.001). We found that a transmural extent of infarction of 0.50 corresponded to a ΔFFR(0.8) threshold of 0.1, and had high sensitivity and specificity (100% and 94.4%, respectively). CONCLUSIONS: Using only an upstream pressure-sensitive guidewire and a partially obstructing balloon during pharmacologic hyperemia, we were able to predict MRI myocardial viability with high accuracy after relief of epicardial stenosis. With further validation, this may prove a useful clinical prognostic tool after percutaneous intervention.