Feasibility of four-dimensional similarity filter for radiation dose reduction in dynamic myocardial computed tomography perfusion imaging.

Rationale and objectives: We aimed to evaluate the impact of four-dimensional noise reduction filtering using a four-dimensional similarity filter (4D-SF) on radiation dose reduction in dynamic myocardial computed tomography perfusion (CTP). Materials and methods: Forty-three patients who underwent dynamic myocardial CTP using 320-row computed tomography (CT) were included in the study. The original images were reconstructed using iterative reconstruction (IR). Three different CTP datasets with simulated noise, corresponding to 25%, 50%, and 75% reduction of the original dose (300 mA), were reconstructed using a combination of IR and 4D-SF. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed, and CT-derived myocardial blood flow (CT-MBF) was quantified. The results were compared between the original and simulated images with radiation dose reduction. Results: The median SNR (first quartile-third quartile) at the original, 25%-, 50%-, and 75%-dose reduced-simulated images with 4D-SF was 8.3 (6.5-10.2), 16.5 (11.9-21.7), 15.6 (11.0-20.1), and 12.8 (8.8-18.1) and that of CNR was 4.4 (3.2-5.8), 6.7 (4.6-10.3), 6.6 (4.3-10.1), and 5.5 (3.5-9.1), respectively. All the dose-reduced-simulated CTPs with 4D-SF had significantly higher image quality scores in SNR and CNR than the original ones (25%-, 50%-, and 75%-dose reduced vs. original images, p < 0.05, in each). The CT-MBF in 75%-dose reduced-simulated CTP was significantly lower than 25%-, 50%- dose-reduced-simulated, and original CTPs (vs. 75%-dose reduced-simulated images, p < 0.05, in each). Conclusion: 4D-SF has the potential to reduce the radiation dose associated with dynamic myocardial CTP imaging by half, without impairing the robustness of MBF quantification.

[A Simulation Surgery of Valve-sparing Aortic Root Replacement Using a Three-dimensional Printed Model].

Aortic valve-sparing surgery is a delicate procedure that requires specialized skills to control aortic valve regurgitation. Therefore, simulating the surgery before performing it on a patient is good practice for inexperienced surgeons. Herein, we present our experience of a simulation surgery using a three-dimensionally printed aortic root model of a 60-year-old man with severe aortic regurgitation and aortic root enlargement. We fabricated the model using multi-slice computed tomography data. The model revealed the two pitfalls:unbalanced commissure position and lower coaptation height of the right coronary cusp. We completed the simulation surgery from the proximal suture and valve reimplantation to coronary ostial reconstructions during approximately three hours with medical staffs. In the actual operation, the aortic valve regurgitation completely disappeared by accurately reconstructing the commissure in the Valsalva graft and adjusting the height of the right coronary cusp using central plication procedure. We believe that carrying out simulations before the actual surgery improves the surgeon's confidence and the patient's outcomes.

Diagnostic accuracy of stress myocardial computed tomography perfusion imaging to detect myocardial ischemia: a comparison with coronary flow velocity reserve derived from transthoracic Doppler echocardiography.

BACKGROUND: Our aim was to evaluate the ability of adenosine triphosphate (ATP)-stress myocardial computed tomography perfusion (CTP) imaging to detect myocardial ischemia in the left anterior descending artery (LAD) territory, and to compare this method with coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography (TTDE). METHODS: ATP-stress CTP and CFVR were performed in 50 patients with stable angina pectoris. Myocardial ischemia assessed from CTP imaging was defined as qualitative visual perfusion defects and reduced myocardial blood flow (MBF) based on quantitative assessment. A cut-off value of CFVR of 2.0 was used. RESULTS: The mean CFVR was 1.9 ± 0.6 in ischemic regions by CTP, whereas it was 2.9 ± 0.8 in non-ischemic regions (p < 0.001). CTP imaging could accurately predict CFVR <2.0 with 84.0% diagnostic accuracy (94.7% sensitivity, 77.4% specificity, 72.0% positive predictive value, and 96.0% negative predictive value). When receiver operating characteristic curve analysis of the MBF data was performed to detect CFVR <2.0, the area under the curve was 0.89, and the optimal MBF cut-off value was 1.43 mL/g/min. CONCLUSIONS: This study suggests that qualitative and quantitative assessment of ATP-stress CTP exhibits a good correlation with CFVR for evaluation of myocardial ischemia.

Clinical application of four-dimensional noise reduction filtering with a similarity algorithm in dynamic myocardial computed tomography perfusion imaging.

We aimed to evaluate the effects of four-dimensional noise reduction filtering using a similarity algorithm (4D-SF) on the image quality and hemodynamic parameter of dynamic myocardial computed tomography perfusion (CTP). Sixty-eight patients who underwent dynamic myocardial CTP for the assessment of coronary artery disease were enrolled. Dynamic CTP was performed using a 320-row CT with low tube voltage scan (80 kVp). Two different datasets of dynamic CTP were reconstructed using iterative reconstruction (IR) alone and a combination of IR and 4D-SF. Qualitative (5-grade scale) and quantitative image quality scores were assessed, and the CT-derived myocardial blood flow (CT-MBF) was quantified. These results were compared between the two different CTP images. The qualitative image quality in CTP images reconstructed with IR and 4D-SF was significantly higher than that with IR alone (noise score: 4.7 vs. 3.4, p < 0.05). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in CTP images reconstructed with IR and 4D-SF were significantly higher than those with IR alone (SNR: 20.6 vs. 9.7; CNR: 7.9 vs. 3.9, respectively; p < 0.05). There was no significant difference in mean CT-MBF between the two sets of CTP images (3.01 vs. 3.03 mL/g/min, p = 0.1081). 4D-SF showed incremental value in improving image quality in combination with IR without altering CT-MBF quantification in dynamic myocardial CTP imaging with a low tube potential.

Continuous thermodilution to assess absolute flow and microvascular resistance: validation in humans using [15O]H2O positron emission tomography.

AIMS: Continuous thermodilution is a novel technique to quantify absolute coronary flow and microvascular resistance (MVR). Notably, intracoronary infusion of saline elicits maximal hyperaemia, obviating the need for adenosine. The primary aim of this study was to validate continuous thermodilution in humans by comparing invasive measurements to [15O]H2O positron emission tomography (PET). As a secondary goal, absolute flow and MVR were compared between invasive measurements obtained with and without adenosine. METHODS AND RESULTS: Twenty-five patients underwent coronary computed tomography angiography (CCTA), [15O]H2O PET, and invasive assessment. Absolute coronary flow and MVR were measured in the left anterior descending and left circumflex artery using a dedicated infusion catheter and a temperature/pressure sensor-tipped guidewire. Invasive measurements were performed with and without adenosine. In order to compare invasive flow measurements with PET perfusion, subtending myocardial mass of the investigated vessels was derived from CCTA using the Voronoi algorithm. Invasive and non-invasive measurements of adenosine-induced hyperaemic flow and MVR showed strong correlation (r = 0.91; P < 0.001 for flow and r = 0.85; P < 0.001 for MVR) and good agreement [intraclass correlation coefficient (ICC) = 0.90; P < 0.001 for flow and ICC = 0.79; P < 0.001 for MVR]. Absolute flow and MVR also correlated well between measurements with and without adenosine (r = 0.97; P < 0.001 for flow and r = 0.98; P < 0.001 for MVR) and showed good agreement (ICC = 0.96; P < 0.001 for flow and ICC = 0.98; P < 0.001 for MVR). CONCLUSIONS: Continuous thermodilution is an accurate method to measure absolute coronary flow and MVR, which is evidenced by strong agreement with [15O]H2O PET derived flow and resistance. Absolute flow and MVR correlate highly between invasive measurements obtained with and without adenosine, which confirms that intracoronary infusion of room temperature saline elicits steady-state maximal hyperaemia.

Positron emission tomography/computed tomography detection of increased 18F-fluorodeoxyglucose uptake in the cardiac atria of patients with atrial fibrillation.

BACKGROUND: Direct evidence of inflammatory activity in the atria of patients with atrial fibrillation (AF) is scarce. We assessed the capability of positron-emission tomography/computed tomography (PET/CT) to diagnose AF based on fluorodeoxyglucose (FDG) uptake in the atrial wall. METHODS AND RESULTS: Among 8233 patients who underwent FDG-PET/CT as work-up for malignancies, we identified 180 consecutive patients with AF (2.2%). Of those, we selected 137 patients who had fasted >12 h before FDG injection for inclusion in the experimental group (88 men and 49 women; age: 72.7 ±â€¯8.9 years). Controls were 62 age- and sex-matched patients without AF. For visual analysis, we used a 4-point grading system. For quantitative analysis, we used the maximum standard uptake value (SUVmax) in the left (LA) and right atrial (RA) myocardium and the target-to-background ratio (TBR) of SUVmax to blood pool activity. The sensitivity, specificity, and positive-predictive value for detecting AF visually were 54.0%, 95.2%, and 96.1%, respectively; for quantitative analysis, the respective values were 65.7%, 75.8%, and 85.7%. Multivariable analysis of 11 clinical and imaging variables showed significant associations with RA SUVmax (odds ratio [OR]: 14.353, P = 0.026) and LA volume (OR: 1.371, P = 0.0001). The RA TBR was greater in cases with persistent AF than in those with paroxysmal AF (P < 0.0001). Pathological investigation of 4 autopsy hearts confirmed infiltration of extravascular macrophages and lymphocytes in the regions with FDG uptake. CONCLUSIONS: Higher atrial FDG uptake was associated with AF. PET/CT could be a useful tool for detecting local inflammation in the atria with AF.

To what extent can 3D model replicate dimensions of individual mitral valve prolapse?

Determining the complex geometry of mitral valve prolapse is often difficult. We constructed 3D models of six prolapsed mitral valves for surgical assessment, and evaluated how accurately the models could replicate individual valve dimensions. 3D polygon data were constructed based on an original segmentation method for computed tomography images. The model's replication performance was confirmed via dimensional comparison between the actual hearts during surgery and those models. The results revealed that the prolapsed segments matched in all cases; however, torn chordae were replicated in four cases. The mean height differences were 0.0 mm (SD 1.6, range - 2 to + 2 mm) for the anterolateral side, 0.0 mm (SD 1.7, range - 2 to + 2 mm) for the prolapsed leaflet center, and - 1.5 mm (SD 0.6, range - 1 to - 2 mm) for the posteromedial side. Regression analysis showed a strong and positive correlation, and Bland-Altman plots indicated quantitative similarity of the models to the actual hearts. We concluded that our 3D valve models could replicate the actual mitral valve prolapses within acceptable dimensional differences. Our concepts are useful for better 3D valve creation and better surgical planning with reliable 3D valve models.

Estimation of myocardial flow reserve utilizing an ultrafast cardiac SPECT: Comparison with coronary angiography, fractional flow reserve, and the SYNTAX score.

BACKGROUND: Quantitative assessment of myocardial flow reserve (MFR) by single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is challenging but may facilitate evaluation of multi-vessel coronary artery disease (CAD). METHODS: We enrolled 153 patients with suspected or known CAD, referred for pharmacological stress MPI. They underwent a 99mTc-perfusion stress/rest SPECT with an ultrafast cadmium-zinc-telluride (CZT) camera. Dynamic data were acquired and time-activity curves fitted to a 1-tissue compartment analysis with input function. K1 was assigned for stress and rest data. The MFR index (MFRi) was calculated as K1 stress/K1 at-rest. The findings were validated by invasive coronary angiography in 69 consecutive patients. RESULTS: The global MFRi was 1.46 (1.16-1.76), 1.33 (1.12-1.54), and 1.18 (1.01-1.35), for 1-vessel disease (VD), 2-VD, and 3-VD, respectively. In the 3-VD, global MFRi was lower than that in 0-VD (1.63 [1.22-2.04], P<0.0001) and 1-VD (P=0.003). Multivariate logistic regression analysis for 3-VD showed significant associations with smoking history (odds ratio [OR]: 4.4 [0.4-8.4]), left ventricular ejection fraction (OR: 61.6 [57.5-66.0]), and global MFRi (OR: 119.6 [111.5-127.7], P=0.002). A cut-off value of 1.3 yielded 93.3% sensitivity and 75.9% specificity for diagnosing 3-VD. Fractional flow reserve positively correlated with regional MFRi (r=0.62, P=0.008), and the SYNTAX score correlated negatively with global MFRi (r=0.567, P=0.0003). CONCLUSION: We developed and validated a clinically available method for MFR quantification by dynamic 99mTc-perfusion SPECT utilizing a CZT camera, which improves the detectability of multi-vessel CAD.

Integrating CT Myocardial Perfusion and CT-FFR in the Work-Up of Coronary Artery Disease.

OBJECTIVES: The aim of this study was to investigate the individual and combined accuracy of dynamic computed tomography (CT) myocardial perfusion imaging (MPI) and computed tomography angiography (CTA) fractional flow reserve (FFR) for the identification of functionally relevant coronary artery disease (CAD). BACKGROUND: Coronary CTA has become an established diagnostic test for ruling out CAD, but it does not allow interpretation of the hemodynamic severity of stenotic lesions. Two recently introduced functional CT techniques are dynamic MPI and CTA FFR using computational fluid dynamics. METHODS: From 2 institutions, 74 patients (n = 62 men, mean age 61 years) planned for invasive angiography with invasive FFR measurement in 142 vessels underwent CTA imaging and dynamic CT MPI during adenosine vasodilation. A patient-specific myocardial blood flow index was calculated, normalized to remote myocardial global left ventricular blood flow. CTA FFR was computed using an on-site, clinician-operated application. Using binary regression, a single functional CT variable was created combining both CT MPI and CTA FFR. Finally, stepwise diagnostic work-up of CTA FFR with selective use of CT MPI was simulated. The diagnostic performance of CT MPI, CTA FFR, and CT MPI integrated with CTA FFR was evaluated using C statistics with invasive FFR, with a threshold of 0.80 as a reference. RESULTS: Sensitivity, specificity, and accuracy were 73% (95% confidence interval [CI]: 61% to 86%), 68% (95% CI: 56% to 80%), and 70% (95% CI: 62% to 79%) for CT MPI and 82% (95% CI: 72% to 92%), 60% (95% CI: 48% to 72%), and 70% (63% to 80%) for CTA FFR. For CT MPI integrated with CTA FFR, diagnostic accuracy was 79% (95% CI: 71% to 87%), with improvement of the area under the curve from 0.78 to 0.85 (p < 0.05). Accuracy of the stepwise approach was 77%. CONCLUSIONS: CT MPI and CTA FFR both identify functionally significant CAD, with comparable accuracy. Diagnostic performance can be improved by combining the techniques. A stepwise approach, reserving CT MPI for intermediate CTA FFR results, also improves diagnostic performance while omitting nearly one-half of the population from CT MPI examinations.

Increased Aortic Valve Calcification in Familial Hypercholesterolemia: Prevalence, Extent, and Associated Risk Factors.

BACKGROUND: Familial hypercholesterolemia is typically caused by LDL receptor (LDLR) mutations that result in elevated levels of LDL cholesterol (LDL-C). In homozygous FH, the prevalence of aortic valve calcification (AoVC) reaches 100% and is often symptomatic. OBJECTIVES: The objective of this study was to investigate the prevalence, extent, and risk-modifiers of AoVC in heterozygous FH (he-FH) that are presently unknown. METHODS: Asymptomatic patients with he-FH and 131 non-familial hypercholesterolemia controls underwent CT computed tomography calcium scoring. AoVC was defined as the presence of calcium at the aortic valve leaflets. The extent of AoVC was expressed in Agatston units, as the AoVC-score. We compared the prevalence and extent of AoVC between cases and controls. In addition, we investigated risk modifiers of AoVC, including the presence of LDLR mutations without residual function (LDLR-negative mutations), maximum untreated LDL-cholesterol (maxLDL), LDL-C, blood pressure, and coronary artery calcification (CAC). RESULTS: We included 145 asymptomatic patients with he-FH (93 men; mean age 52 ± 8 years) and 131 non-familial hypercholesterolemia controls. The prevalence (%) and AoVC-score (median, IQR) were higher in he-FH patients than in controls: 41%, 51 (9-117); and 21%, 21 (3-49) (p < 0.001 and p = 0.007). Age, untreated maxLDL, CAC, and diastolic blood pressure were independently associated with AoVC. LDLR-negative mutational he-FH was the strongest predictor of the AoVC-score (OR: 4.81; 95% CI: 2.22 to 10.40; p = <0.001). CONCLUSIONS: Compared to controls, he-FH is associated with a high prevalence and a large extent of subclinical AoVC, especially in patients with LDLR-negative mutations, highlighting the critical role of LDL-C metabolism in AoVC etiology.

Relative myocardial blood flow by dynamic computed tomographic perfusion imaging predicts hemodynamic significance of coronary stenosis better than absolute blood flow.

OBJECTIVES: Quantitative myocardial perfusion imaging by computed tomography (CT) was recently introduced to calculate myocardial blood flow (MBF). Because absolute MBF thresholds may be affected by technique, methodology, and the microvasculature, we investigated whether a relative measure of MBF improves accuracy to identify hemodynamically significant coronary stenosis. MATERIALS AND METHODS: In this prospective study, 42 patients (mean [SD] age, 62.3[8.7] years; 8 women) with suspected or known coronary disease underwent dynamic CT myocardial perfusion imaging using adenosine vasodilation, before invasive angiography (coronary angiography) with fractional flow reserve (FFR). Within each myocardial territory MBF, the MBF relative to remote myocardium (MBFratio) was calculated and compared with coronary angiography and FFR. RESULTS: Of the 91 vessels interrogated by FFR (median, 0.81; interquartile range, 0.73-0.94), 45 vessels (49%) had an FFR value lower than 0.8 and were considered hemodynamically significant. Hyperemic MBF was lower in ischemic territories: 75.6 ± 22.5 mL per 100 mL/min versus 98.3 ± 23.1 mL per 100 mL/min (P < 0.0001). The MBFratio correlated better with FFR (P = 0.76) than the absolute MBF did (P = 0.52). Receiver operating curve analysis showed better discrimination by MBFratio: area under the curve of 0.85 versus 0.75 (P = 0.02). The MBF of remote myocardium varied between 60.7 and 167.2 mL per 100 mL/min and was lower in patients without heart rate acceleration (P = 0.0035). CONCLUSIONS: The MBFratio seems to better identify hemodynamically significant coronary artery disease than does the absolute MBF determined by dynamic CT perfusion imaging. This may be caused by microvascular status or related to the methodology.

Adenosine triphosphate stress dual-source computed tomography to identify myocardial ischemia: comparison with invasive coronary angiography.

PURPOSE: The purpose of this study was to investigate the utility incremental diagnostic value of combined assessment with coronary CT angiography (CCTA) and myocardial CT perfusion imaging (CTP) using dual-energy technology with an Adenosine Triphosphate (ATP) load technique. MATERIALS AND METHODS: Twenty-one patients underwent ATP-provocation dual-energy CT and CAG. We compared the diagnostic accuracy with CAG, for ischemic region due coronary stenosis by CCTA alone and CCTA combined with CTP (Combined CCTA/CTP). RESULTS: All of 21 patients CTP images could be evaluated, however 8 CCTA images could not be evaluated by calcification and motion artifact, so assessability was 61.9% (13/21) for CCTA alone, and 100% for Combined CCTA/CTP. With CAG results as a comparison, the sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 83.3% (20/24), 74.4% (29/39), 66.7% (20/30), and 87.8% (29/33) for CCTA alone, and 66.7% (16/24), 92.3% (36/39), 84.2% (16/19), and 81.8% (36/44) for combined CCTA/CTP. The diagnostic accuracy of the two methods were 77.8% (49/63) and 82.5% (52/63). CONCLUSION: Dual-energy CT may be a useful modality for perfusion assessment and correlated well with the severity of stenosis on CAG. This technique may even be of use in cases of severe calcification in the coronary artery wall.

Combined supine and prone myocardial perfusion single-photon emission computed tomography with a cadmium zinc telluride camera for detection of coronary artery disease.

BACKGROUND: Myocardial perfusion SPECT (MPS) traditionally requires the patient to be in the supine position, but diaphragmatic attenuation of the inferior wall reduces test specificity. The aim of this study was to assess the feasibility of combined MPS in the supine and prone positions using a novel cadmium zinc telluride (CZT) camera. METHODS AND RESULTS: A total of 276 consecutive patients with suspected/known coronary artery disease (CAD) who underwent single-day (99m)Tc-tetrofosmin or (99m)Tc-sestamibi stress/rest CZT SPECT, were enrolled in the study. Seventy-six underwent coronary angiography. Five-minute scan in the supine (S) position and thereafter in the prone (P) position produced images that were visually interpreted to obtain summed stress (SSS) and rest (SRS) scores. A combined stress score (C-SSS) was calculated by grouping anterior perfusion defects observed during supine imaging with inferior half segments observed during prone imaging. The SSS for the supine, prone, and combined protocols were 9±8, 7±8, and 7±8, respectively (P<0.0001). The SRS were 5±8, 4±7, and 6±7, respectively (P=0.005). The area under the ROC curve for the S-SSS, P-SSS, and C-SSS scores was 0.815 (95% CI: 0.713-0.917), 0.813 (0.711-0.914), and 0.872 (0.783-0.961), respectively. Corresponding sensitivities and specificities for detecting CAD were 87% and 50%, 80% and 77%, and 85% and 82%, respectively. C-SSS had significantly better specificity and accuracy than S-SSS (P<0.05). CONCLUSIONS: Combined imaging with a CZT camera is suitable for routine clinical MPS and provides greater diagnostic accuracy than supine imaging alone.

Qualitative and quantitative assessment of adenosine triphosphate stress whole-heart dynamic myocardial perfusion imaging using 256-slice computed tomography.

BACKGROUND: The aim of this study was to investigate the correlation of the qualitative transmural extent of hypoperfusion areas (HPA) using stress dynamic whole-heart computed tomography perfusion (CTP) imaging by 256-slice CT with CTP-derived myocardial blood flow (MBF) for the estimation of the severity of coronary artery stenosis. METHODS AND RESULTS: Eleven patients underwent adenosine triphosphate (0.16 mg/kg/min, 5 min) stress dynamic CTP by 256-slice CT (coverage: 8 cm, 0.27 s/rotation), and 9 of the 11 patients underwent coronary angiography (CAG). Stress dynamic CTP (whole-heart datasets over 30 consecutive heart beats in systole without spatial and temporal gaps) was acquired with prospective ECG gating (effective radiation dose: 10.4 mSv). The extent of HPAs was visually graded using a 3-point score (normal, subendocardial, transmural). MBF (ml/100g/min) was measured by deconvolution. Differences in MBF (mean ± standard error) according to HPA and CAG results were evaluated. In 27 regions (3 major coronary territories in 9 patients), 11 coronary stenoses (> 50% reduction in diameter) were observed. In 353 myocardial segments, HPA was significantly related to MBF (P < 0.05; normal 295 ± 94; subendocardial 186 ± 67; and transmural 80 ± 53). Coronary territory analysis revealed a significant relationship between coronary stenosis severity and MBF (P < 0.05; non-significant stenosis [< 50%], 284 ± 97; moderate stenosis [50-70%], 184 ± 74; and severe stenosis [> 70%], 119 ± 69). CONCLUSION: The qualitative transmural extent of HPA using stress whole-heart dynamic CTP imaging by 256-slice CT exhibits a good correlation with quantitative CTP-derived MBF and may aid in assessing the hemodynamic significance of coronary artery disease.

Impact of iterative reconstruction on CT coronary calcium quantification.

OBJECTIVES: We evaluated the influence of sinogram-affirmed iterative reconstruction (SAFIRE) on the coronary artery calcium (CAC) score by computed tomography (CT). MATERIALS AND METHODS: Seventy patients underwent CAC imaging by 128-slice dual-source CT. CAC volume, mass and Agatston score were calculated from images reconstructed by filtered back projection (FBP) without and with incremental degrees of the SAFIRE algorithm (10-50 %). We used the repeated measuring test and the Steel-Dwass test for multiple comparisons of values and the difference ratio among different SAFIRE groups using the FBP as reference. RESULTS: The median Agatston score (range) decreased with incremental SAFIRE degrees: 163 (0.1 - 3,393.3), 158.4 (0.3 - 3,079.3), 137.7 (0.1 - 2,978.0), 120.6 (0 - 2,783.6), 102.6 (0 - 2,468.4) and 84.1 (0 - 2,186.9) for 0 % (FBP), 10 %, 20 %, 30 %, 40 % and 50 % SAFIRE, respectively (P < 0.05). In comparison with FBP, CAC volume (from 8.1 % to 47.7 %), CAC mass (from 5.3 % to 44.7 %) and CAC Agatston score (from 7.3 % to 48.4 %) all decreased with increasing SAFIRE from 10 % to 50 %, respectively (P < 0.05). High-grade SAFIRE resulted in the disappearance of detectable calcium in three cases with low calcium burden. CONCLUSION: SAFIRE noise reduction techniques significantly affected the CAC, which potentially alters perceived cardiovascular risk.

Stress/rest circumferential strain in non-ischemia, ischemia, and infarction--quantification by 3 Tesla tagged magnetic resonance imaging.

BACKGROUND: Adenosine triphosphate (ATP) induces relative hypoperfusion in significantly stenotic coronary arteries, but its effect on myocardial strain has not been used clinically for the detection of ischemia. The purpose of this study was to quantify ATP-stress-induced contractile impairment as altered myocardial strain in coronary artery disease (CAD) using tagged magnetic resonance (MR) and to evaluate its diagnostic capability in comparison with ATP-stress myocardial perfusion-MR. METHODS AND RESULTS: Tagged MR and perfusion-MR under ATP-stress and rest conditions and late gadolinium enhancement (LGE) MR imaging were performed in 22 patients with suspected CAD. The peak absolute value of the circumferential strain (C-strain) was measured in 12 segments. Myocardial segments were categorized as non-ischemic (n=201), ischemic (n=42), or infarcted (n=21) according to the perfusion-MR and LGE MR imaging results. The absolute C-strain was significantly greater under ATP-stress (19±13%) (mean±SD) than under at-rest (15±11%, P<0.001) conditions in non-ischemic segments. Conversely, the absolute C-strain was significantly lower under ATP-stress (10±13%) than under at-rest (16±6%, P<0.01) conditions in ischemic segments. Optimal cutoff values for stress C-strain (-17.5%) could successfully differentiate segments with ischemia or infarction from non-ischemic ones with a sensitivity of 86%, a specificity of 65%, and an area under the curve of 0.79. CONCLUSIONS: C-strain analysis using tagged MR could detect ATP-stress-induced contractile impairment in ischemic myocardium.

Tailored flow alteration treatment for intracranial internal carotid artery aneurysms: strategy beyond parent artery occlusion with bypass. Case report.

A 58-year-old woman with multiple right internal carotid artery (ICA) aneurysms detected incidentally was referred to us. Three-dimensional computed tomography (CT) angiography revealed a broad-necked paraclinoid aneurysm and an aneurysm on the C(1) segment. Aneurysm clipping with preservation of the anterior choroidal artery and posterior communicating artery was not possible because these vessels could not be adequately identified. Intraoperative digital subtraction angiography during obliteration of the cervical portion of the ICA confirmed retrograde flow from the extracranial-intracranial (EC-IC) bypass to the right ophthalmic artery and stagnation of flow in the aneurysms. The cervical portion of the ICA was ligated. Postoperative three-dimensional CT angiography confirmed complete occlusion of both aneurysms and absence of ischemic lesions involving branches of the ICA. Reversal of the blood flow in the ICA via the EC-IC bypass primarily into the ophthalmic artery as the flow outlet by obliterating the cervical portion of the ICA was successful. To prevent ischemia in the territory fed by the perforating arteries of the ICA, tailored flow alteration treatment may be superior to simple parent artery occlusion of the ICA with/without bypass. The pattern of flow alteration should be deliberately based on individual anatomic variations, especially the preservation of flow outlets.

Endosaccular embolization for a ruptured distal anterior inferior cerebellar artery aneurysm.

We report a rare case of a ruptured distal anterior inferior cerebellar artery aneurysm that was successfully treated by endosaccular embolization, and review the literature on the results of endovascular surgery for this condition.

Efficacy of endovascular surgery for ruptured aneurysms with vasospasm of the parent artery.

INTRODUCTION: In the presence of vasospasm it is recommended that surgical clipping for a ruptured aneurysm should be delayed until it disappears, but this may be associated with re-rupture of the aneurysm resulting in a poor outcome. The indications for endovascular coil embolization in such cases are discussed. METHODS: Since November 2002, endovascular coil embolization has been used in 18 consecutive patients with ruptured aneurysm with vasospasm of the parent artery ranging from 2 to 28 days (mean 9 days) after the initial subarachnoid hemorrhage. After successful obliteration of the aneurysm, a microcatheter preceded by a guidewire was introduced into the peripheral vessels with vasospasm of the A2 or M2 portions in order to release the vasospasm mechanically. RESULTS: Endovascular procedures were performed successfully in all but one of the cases (94%), resulting in complete occlusion in 14 of 17 patients and mild dilation of the vasospasm in all 17 patients without technical complications or re-rupture of the aneurysm. In the one case of failure because of a tortuous artery, surgical clipping was performed after disappearance of the vasospasm. Cerebral infarction occurred in four patients, but only one correlated with the distribution of catheterization and the neurological deficits had completely disappeared 3 months after the onset. CONCLUSION: Catheterization of parent vessels in cases of vasospasm is safe for coiling and also mechanically releases vasospasm. Vasospasm of M2 and A2 segments can be treated with microcatheterization only.

Contrast stasis in large and giant internal carotid artery aneurysms as a good prognostic factor for endovascular coil embolization: retrospective study.

OBJECTIVE: Before treatment for large and giant aneurysms, we need some of the predictors to prognose a good result. In this retrospective study, we attempted to determine criteria such as angiographic signs to identify good candidates for effective endovascular surgery. METHODS: This study involved 45 patients with large or giant aneurysms treated by endovascular embolization. For angiographic study, we delivered a bolus injection of contrast medium. All aneurysms were confirmed angiographically and the morphology was defined in detail before endovascular embolization. We divided the patients into two groups based on angiographic findings. Group A (n=16) manifested stasis of the contrast medium in the aneurysm on venous phase. Group B (n=29) exhibited other findings. We retrospectively evaluated the relationship between stasis of the contrast medium in the aneurysm and results of endovascular embolization. RESULTS AND DISCUSSION: There was no significant difference between the two groups with respect to the size of the aneurysm. However, the neck/dome ratio (P=0·04) and size of the neck (P=0·003) were significantly different between groups A and B. The morphological outcome was better in group A than group B (P=0·03). We demonstrate that contrast stasis is a good predictor of outcome in patients with large or giant aneurysms to consider the endovascular embolization. Hemodynamic studies on large patient populations may reveal other factors predictive of a good treatment outcome.