Dynamic CT Perfusion Research Articles

Beneficial effects of exercise training on physical performance in patients with vasospastic angina

AimsIn vasospastic angina (VSA), coronary vasomotion abnormalities could develop not only in epicardial coronary arteries but also in coronary microvessels, where calcium channel blockers (CCBs) have limited efficacy. However, efficacy of exercise training for VSA remains to be elucidated. We thus aimed to examine whether vasodilator capacity of coronary microvessels is impaired in VSA patients, and if so, whether exercise exerts beneficial effects on the top of CCBs. MethodsWe performed 2 clinical protocols. In the protocol 1, we measured myocardial blood flow (MBF) using adenosine-stress dynamic computed tomography perfusion (CTP) in 38 consecutive VSA patients and 17 non-VSA controls. In the protocol 2, we conducted randomized controlled trial, where 20 VSA patients were randomly assigned to either 3-month exercise training group (Exercise group) or Non-Exercise group (n= 10 each). ResultsIn the protocol 1, MBF on CTP was significantly decreased in the VSA group compared with the Non-VSA group (138 ± 6 vs 166 ± 10 ml/100 g/min, P = 0.02). In the protocol 2, exercise capacity was significantly increased in the Exercise group than in the Non-Exercise group (11.5 ± 0.5 to 15.4 ± 1.8 vs 12.6 ± 0.7 to 14.0 ± 0.8 ml/min/kg, P < 0.01). MBF was also significantly improved after 3 months only in the Exercise group (Exercise group, 145 ± 12 to 172 ± 8 ml/100 g/min, P < 0.04; Non-Exercise group, 143 ± 14 to 167 ± 8 ml/100 g/min, P = 0.11), although there were no significant between-group differences. ConclusionsThese results provide the first evidence that, in VSA patients, exercise training on the top of CCBs treatment may be useful to improve physical performance, although its effect on MBF may be minimal.

Abstract 12914: Multicenter Study of Diagnostic Performance of Noninvasive Coronary Angiography and Dynamic Myocardial Perfusion Imaging Using Dual Source Computed Tomography: The AMPLIFiED Study

Introduction: Single-center studies indicated a high diagnostic accuracy of dynamic computed tomography perfusion (CTP) imaging in the diagnosis of hemodynamically significant coronary artery disease (CAD). However, no prospective multicenter study has assessed the performance of combined coronary computed tomography angiography (CTA) and dynamic CTP. Hypothesis: In this prospective multicenter study, we assessed the hypothesis that dynamic CTP can provide an incremental diagnostic value over CTA detecting hemodynamically significant CAD defined by invasive coronary angiography (ICA) with fractional flow reserve (FFR). Methods: Seven centers enrolled 165 patients with suspected or known CAD, who were clinically referred for ICA. CTA and dynamic CTP were performed using dual-source CT prior to ICA. FFR was done as part of ICA in case of 26-90% coronary diameter stenosis. Hemodynamically significant stenosis was defined as of FFR&lt;0.8 or ≥90% stenosis on ICA. Three blinded independent core laboratories analyzed CTA, CTP and ICA. Results: The study protocol was completed in 157 participants and hemodynamically significant stenosis was detected in 112 of 442 vessels (25%) and 123 of 157 patients (78%). According to receiver operating characteristic curve analysis, CTA showed an area under the curve (AUC) of 0.81 (95% confidence interval [CI], 0.73-0.86) on the patient level and 0.80 (95% CI, 0.76-0.84) on the vessel level. Adding dynamic CTP to CTA significantly increased the AUC to 0.85 (95% CI, 0.78-0.90; p=0.027) on the patient level and to 0.84 (95% CI, 0.80-0.87; p=0.002) on the vessel level. In the subgroups of patients with 1-, 2- and 3-vessel disease by CTA, the addition of dynamic CTP to CTA significantly increased AUC from 0.80 to 0.84 (p=0.041) in 2-vessel disease and from 0.65 to 0.73 (p=0.022) in 3-vessel disease, but not in 1-vessel disease (from 0.84 to 0.87, p=0.265). Conclusion: In this first prospective multicenter study on dynamic CTP, the combination of anatomical assessment with coronary CTA and functional evaluation with dynamic CTP allowed more accurate detection of hemodynamically significant coronary artery stenosis. Improved diagnostic performance with dynamic CTP was mainly obtained when multivessel disease was suspected by CTA.

Myocardial perfusion assessment in the infarct core and penumbra zones in an in-vivo porcine model of the acute, sub-acute, and chronic infarction.

To assess the longitudinal changes of microvascular function in different myocardial regions after myocardial infarction (MI) using myocardial blood flow derived by dynamic CT perfusion (CTP-MBF), and compare CTP-MBF with the results of cardiac magnetic resonance (CMR) and histopathology. The CTP scanning was performed in a MI porcine model 1 day (n = 15), 7 days (n = 10), and 3 months (n = 5) following induction surgery. CTP-MBF was measured in the infarcted myocardium, penumbra, and remote myocardium, respectively. CMR perfusion and histopathology were performed for validation. From baseline to follow-up scans, CTP-MBF presented a stepwise increase in the infarcted myocardium (68.51 ± 11.04 vs. 86.73 ± 13.32 vs. 109.53 ± 26.64 ml/100 ml/min, p = 0.001) and the penumbra (104.92 ± 29.29 vs. 120.32 ± 24.74 vs. 183.01 ± 57.98 ml/100 ml/min, p = 0.008), but not in the remote myocardium (150.05 ± 35.70 vs. 166.66 ± 38.17 vs. 195.36 ± 49.64 ml/100 ml/min, p = 0.120). The CTP-MBF correlated with max slope (r = 0.584, p < 0.001), max signal intensity (r = 0.357, p < 0.001), and time to max (r = - 0.378, p < 0.001) by CMR perfusion. Moreover, CTP-MBF defined the infarcted myocardium on triphenyl tetrazolium chloride staining (AUC: 0.810, p < 0.001) and correlated with microvascular density on CD31 staining (r = 0.561, p = 0.002). CTP-MBF could quantify the longitudinal changes of microvascular function in different regions of the post-MI myocardium, which demonstrates good agreement with contemporary CMR and histopathological findings. • The CT perfusion-based myocardial blood flow (CTP-MBF) could quantify the microvascular impairment in different myocardial regions after myocardial infarction (MI) and track its recovery over time. • The assessment of CTP-MBF is in good agreement with contemporary cardiac MRI and histopathological findings, which potentially facilitates a rapid approach for pathophysiological insights following MI.

Reduced Left Ventricular Myocardial Blood Flow After Radiation Therapy For Thoracic Esophagus Cancer: A Study Using Stress Dynamic Perfusion CT

Radiation therapy (RT) has greatly contributed to improving the prognosis of cancer in the thoracic region. As treatment outcomes improve, myocardial disorders induced by RT have become a serious problem. To investigate myocardial disorder after RT for esophageal cancer using myocardial stress dynamic computed tomography perfusion (CTP) before and after RT. Fifteen patients with esophageal cancer scheduled for RT were prospectively enrolled between January 2017 and January 2019. CTP was performed before and 3 months after RT to investigate the relationship between changes in hyperemic myocardial blood flow (hMBF) and the radiation dose for the left ventricle (LV). Fifteen segments of LV myocardium were classified into 3 groups according to radiation dose: <20 Gy (Group A), 20–40 Gy (Group B) and >40 Gy (Group C), by fusing CT angiography (CTA) onto radiation planning CT images. Twelve of 15 patients completed CTP before and at a median of 2.8±1.34 months after RT. A total of 180 LV segments (Group A, n = 122; B, n = 39; and C, n = 19) was analyzed. Groups B (pre-RT 147.5 ± 27.7 mL/min/100g vs post-RT 135.5 ± 25.4 mL/min/100g, p = 0.035) and C(pre-RT 146.3 ± 27.0 mL/min/100g vs post-RT 126.0 ± 16.0 mL/min/100g, p = 0.022) showed significant reduction in hMBF, while there was no significant difference in hMBF for Group A between pre- and post-RT (145.3 ± 26.3 mL/min/100g vs 146.4 ± 19.3 mL/min/100g, p = 0.729). There was a significant difference in ΔhMBF between Groups A and B (1 ± 27.5 mL/min/100g vs -12 ± 33.9 mL/min/100g, p = 0.014). Significant negative correlation was found between the LV radiation dose and change in hMBF (r = -0.263, p = 0.004). Significant reduction in hMBF was observed with CTP taken approximately 3 months after RT in the LV segments for which radiation dose ≥20 Gy was administered. The alteration in hMBF was related to LV radiation dose. These findings should increase our knowledge of ionizing radiation injury to the heart, and provide important insights for RT planning optimization to prevent or mitigate the adverse effects.

Estimation of renal function using kidney dynamic contrast material-enhanced CT perfusion: accuracy and feasibility.

To measure glomerular filtration rates (GFRs) using kidney dynamic contrast material-enhanced (DCE)-CT perfusion scans and correlate them with estimated GFRs (eGFRs). Split-bolus CT urography, including pre-contrast and nephrographic-excretory phase imaging, was performed with a kidney DCE-CT perfusion scan protocol. We analysed 55 patients with suspected renal disease. All CT acquisitions were obtained on a 256-slice CT scanner for 3.5 min continuously with shallow breathing. Renal volume, perfusion and permeability values were calculated using a dedicated prototype software. Based on Patlak plots, split and total renal GFR values were determined. Paired t-tests, Pearson's correlation analysis and Bland-Altman plots were used for comparisons between kidney DCE-CT perfusion scan-derived GFR (CT-GFR) and the corresponding eGFR value. The p values < 0.05 were considered statistically significant. The mean CT-GFR was 91.19 ± 20.71 mL/min/1.73 m2. The eGFR values based on the CKD-EPI and MDRD equations were 89.64 ± 19.74 mL/min/1.73 m2 and 89.50 ± 24.89 mL/min/1.73 m2, respectively. No statistically significant differences were found between CT-GFR and eGFRs (p > 0.05). Excellent correlation and agreement between CT-GFR and eGFRs (correlation coefficient r = 0.91 for CKD-EPI and 0.84 for MDRD equations, respectively) were confirmed. Kidney DCE-CT perfusion is an accurate and feasible technique to assess renal function.

Virtual monoenergetic reconstructions of dynamic DECT acquisitions for calculation of perfusion maps of blood flow: Quantitative comparison to conventional, dynamic 80 kVp CT perfusion

PurposeInvestigation of potential improvements in dynamic CT perfusion measurements by exploitation of improved visualization of contrast agent in virtual monoenergetic reconstructions of images acquired with dual-energy computed tomography (DECT). MethodFor 17 patients with pancreatic carcinoma, dynamic dual-source DECT acquisitions were performed at 80kVp/Sn140kVp every 1.5 s over 51 s. Virtual monoenergetic images (VMI) were reconstructed for photon energies between 40 keV and 150 keV (5 keV steps). Using the maximum-slope model, perfusion maps of blood flow were calculated from VMIs and 80kVp images and compared quantitatively with regard to blood flow measured in regions of interest in healthy tissue and carcinoma, standard deviation (SD), and absolute-difference-to-standard-deviation ratio (ADSDR) of measurements. ResultsOn average, blood flow calculated from VMIs increased with increasing energy levels from 114.3 ± 37.2 mL/100 mL/min (healthy tissue) and 45.6 ± 25.3 mL/100 mL/min (carcinoma) for 40 keV to 128.6 ± 58.9 mL/100 mL/min (healthy tissue) and 75.5 ± 49.8 mL/100 mL/min (carcinoma) for 150 keV, compared to 114.2 ± 37.4 mL/100 mL/min (healthy tissue) and 46.5 ± 26.6 mL/100 mL/min (carcinoma) for polyenergetic 80kVp. Differences in blood flow between tissue types were significant for all energies. Differences between perfusion maps calculated from VMIs and 80kVp images were not significant below 110 keV. SD and ADSDR were significantly better for perfusion maps calculated from VMIs at energies between 40 keV and 55 keV than for those calculated from 80kVp images. Compared to effective dose of dynamic 80kVp acquisitions (4.6 ± 2.2 mSv), dose of dynamic DECT/VMI acquisitions (8.0 ± 3.7 mSv) was higher. ConclusionsPerfusion maps of blood flow based on low-energy VMIs between 40 keV and 55 keV offer improved robustness and quality of quantitative measurements over those calculated from 80kVp image data (reference standard), albeit at increased patient radiation exposure.

Low-dose CT perfusion with combined use of CTP and CTP-derived coronary CT angiography at 70kVp: validation with invasive fractional flow reserve.

To investigate the diagnostic performance of 70-kVp stress dynamic myocardial CT perfusion (CTP) as a low-dose, one-stop cardiac CT examination in clinical application. Consecutive symptomatic patients were prospectively recruited and scanned with stress dynamic myocardial CTP. The CTP phase with the best enhancement of the coronary arteries was selected and extracted as the CTP-derived single-phase coronary CT angiography (SP-CTA). The diagnostic performance of CTP and CTP+SP-CTA for functionally significant CAD was assessed. Invasive coronary angiography and fractional flow reserve were used as the reference standard for the myocardial ischemia evaluation. In total, 71 patients (43 men and 28 women; 63.6 ± 8.8years old) underwent the stress dynamic myocardial CTP; 63 vessels (36.2%) from 42 of the patients (59.2%) were identified as causing ischemia. On a per-vessel basis, the sensitivity, specificity, PPV, NPV, and diagnostic accuracy for CTP and CTP+SP-CTA were 77.8%, 93.7%, 87.5%, 88.1%, and 87.9% and 84.1%, 93.7%, 88.3%, 91.2%, and 90.2%, respectively. The area under the curve (AUC) of CTP+SP-CTA (AUC = 0.963; 95%CI, 0.938-0.989) was significantly superior to that of CTP (AUC = 0.922; 95%CI, 0.880-0.964) and that of SP-CTA (AUC = 0.833; 95%CI, 0.765-0.900) alone (all p < 0.01). The mean radiation dose of the CTP examination was 3.8 ± 1.4mSv. CTP-derived SP-CTA improved the diagnostic value of CTP. With a promising performance of myocardial ischemia detection and low radiation dose, the innovative low-dose, one-stop CTP examination is clinically feasible for patients who need to receive a myocardial perfusion assessment. • Myocardial CTP performed well in the evaluation of hemodynamically significant CAD. • CTP-derived single-phase CCTA improved the diagnostic value of CTP. • The combined use of low-dose CTP and CTP-derived CCTA at 70kVp is clinically feasible for CAD patients who need to receive a myocardial perfusion assessment.

The Impact Of Iterative Reconstrustion Algorhitms On Dynamic Computed Tomography Myocardial Perfusion Parameters

Introduction: Coronary computed tomography angiography (CTA) due to its high sensitivity and negative predictive value has emerged as a reliable diagnostic tool for the evaluation of coronary artery disease (CAD) in clinical practice. Recent developments made it possible to perform myocardial perfusion imaging for functional assessment of CAD using CT. We aimed to assess the impact of iterative reconstruction using hybrid- (HIR) and model based iterative reconstruction (IMR) - as compared to filtered back projection reconstruction (FBP) on dynamic perfusion CT (DPCT) derived parameters. Furthermore, we aimed to evaluate the interobserver variability of qualitative and quantitative assessment of ischemia.

Improvement of image quality on low-dose dynamic myocardial perfusion computed tomography with a novel 4-dimensional similarity filter.

The aim of this study was to evaluate the effect of a novel 4-dimensional similarity filter (4DSF) on quantitative and qualitative parameters of low-dose dynamic myocardial computed tomography perfusion (CTP) images.In this retrospective study, medical records of 32 patients with suspected or known coronary artery disease who underwent dynamic myocardial CTP at 80 kV were included. The 4DSF reduces noise by averaging voxels that have similar dynamic behavior after adaptive iterative dose reduction 3D (AIDR3D) and deformable image registration were applied. Qualitative (artefact, contour sharpness, and myocardial homogeneity [1 = poor; 2 = intermediate; 3 = good]) and quantitative measurement (standard deviation [SD] and signal-to-noise ratio [SNR]) were compared between the 4DSF and AIDR3D. Contrast-to-noise ratio (CNR) between ischemic and normal remote myocardium was also assessed using myocardial perfusion magnetic resonance imaging as the reference standard in seven patients.The 4DSF was successfully applied to all the images. Improvement in subjective image quality yielded by 4DSF was higher than that yielded by AIDR3D (homogeneity, 1.0 [3 vs 2]; artefact, 1.5 [3 vs 1.5]; P < .001) in all patients. The 4DSF significantly decreased the SD by 59% (AIDR3D vs 4DSF: 33.5 ± 0.4 vs 13.8 ± 0.4, P < .001), increased the SNR by 134% (AIDR3D vs 4DSF: 4.4 ± 0.2 vs 10.3 ± 0.2, P < .001), and increased the CNR by 131% (AIDR3D vs 4DSF: 1.6 ± 0.2 vs 3.7 ± 0.2, P < .001).The 4DSF improved the qualitative and quantitative parameters of low-dose dynamic myocardial CTP images.

Impact of Abnormal Remote Stress Myocardial Blood Flow by Dynamic CT Perfusion on Clinical Outcomes

The objective of this study was to investigate the incremental prognostic value for adverse events of myocardial blood flow (MBF) derived from stress computed tomography perfusion (CTP) at remote myocardium over cardiac risk factors and ischemia. We prospectively analyzed 242 patients who underwent dynamic CTP and CT angiography. Adverse events were defined as a composite of all-cause mortality, non-fatal myocardial infarction, unstable angina, heart failure requiring hospitalization, peripheral artery disease, and stroke. MBF value was calculated in each myocardial segment and ischemia was defined as mild decrease in MBF in two consecutive segments or moderate decrease in a single segment accompanied with a coronary stenosis ≥50%. The mean MBF of the non-ischemic segments was defined as remote MBF. We divided the patients into two groups by median MBF value of 1.15 ml/min/g. During a median follow-up of 18 months, 18 patients had adverse events. Annual event rate showed a significant difference between patients with low (≤1.15 ml/min/g) and high (>1.15 ml/min/g) MBF (6.1% vs 1.8%, p = 0.02). Univariate analysis showed that low MBF was a significant predictor of events (hazard ratio (HR): 3.4; 95% confidence interval (CI): 1.2 to 12.0; p = 0.02). This relationship maintained significant after adjusted for the presence of ischemia and cardiac risk factors (HR: 3.0; 95%CI: 1.1 to 11.1; p = 0.04). In conclusion, MBF value ≤1.15 ml/min/g derived from dynamic CTP in remote myocardium is significantly related with poor outcome and this relationship was independent of myocardial ischemia and cardiac risk factors.

Self-Supervised Dynamic CT Perfusion Image Denoising With Deep Neural Networks

Dynamic computed tomography perfusion (CTP) imaging is a promising approach for acute ischemic stroke diagnosis and evaluation. Hemodynamic parametric maps of cerebral parenchyma are calculated from repeated CT scans of the first pass of iodinated contrast through the brain. It is necessary to reduce the dose of CTP for routine applications due to the high radiation exposure from the repeated scans, where image denoising is necessary to achieve a reliable diagnosis. In this article, we proposed a self-supervised deep learning method for CTP denoising, which did not require any high-dose reference images for training. The network was trained by mapping each frame of CTP to an estimation from its adjacent frames. Because the noise in the source and target was independent, this approach could effectively remove the noise. Being free from high-dose training images granted the proposed method easier adaptation to different scanning protocols. The method was validated on both simulation and a public real dataset. The proposed method achieved improved image quality compared to conventional denoising methods. On the real data, the proposed method also had improved spatial resolution and contrast-to-noise ratio compared to supervised learning which was trained on the simulation data.

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 (80kVp). 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. 3.03mL/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.

Safety of regadenoson with theophylline reversal during dynamic computed tomography perfusion and magnetic resonance imaging in patients with coronary artery disease.

The use of regadenoson in dynamic computed tomography perfusion (CTP) and magnetic resonance myocardial perfusion imaging (MR MPI) is off‑label. The study aimed to assess the safety of regadenoson with theophylline reversal during CTP and MR MPI in patients with coronary artery disease (CAD). In this prospective study, patients with 1 or more intermediate coronary artery stenoses on computed tomography angiography underwent CTP and MR MPI with 0.4 mg of regadenoson. After examinations, 200 mg of theophylline was given intravenously in 100 ml of saline. Changes in blood pressure (BP) and heart rate (HR) were repeatedly assessed. All side effects and adverse events were recorded. Out of 106 examinations in 53 patients (25 females, 63.5 [8.5] years), all were diagnostic. There were no deaths, myocardial infarctions, severe arrhythmias, high‑grade atrioventricular blocks, or bronchospasms. The most common symptoms were palpitations (17%), hot flushing (8%), chest discomfort (4%), and mild dyspnea (3%). There were no differences between baseline and peak BP. There was an increase in median (interquartile range) peak HR after regadenoson as compared with baseline (MR MPI, 63 [59-75] bpm vs 93 [86-102] bpm; P <0.001; and CTP, 65 [60-70] bpm vs 95 [86-107] bpm; P <0.001). The hemodynamic response to regadenoson and its side effects were completely reversible by theophylline. Regadenoson may be a safe vasodilator for CTP and MR MPI in patients with CAD. The administration of theophylline after perfusion is safe and reverses side effects of regadenoson.

Combined assessment of subtended myocardial volume and myocardial blood flow for diagnosis of obstructive coronary artery disease using cardiac computed tomography: A feasibility study

BackgroundThis study aimed to evaluate the combined diagnostic performance of coronary artery stenosis-subtended myocardial volume (Vsub) and myocardial blood flow (MBFsub) on computed tomography (CT) for detecting obstructive coronary artery disease (CAD) assessed by invasive coronary angiography (ICA) and fractional flow reserve (FFR). MethodsThirty-nine patients who underwent coronary CT angiography (CTA) and stress dynamic myocardial CT perfusion (CTP) prior to ICA were enrolled. Obstructive CAD was defined as severe (≥70%) or moderate (30–69%) stenosis with FFR ≤0.8 on ICA. The Vsub was semi-automatically calculated from coronary CTA data using Voronoi diagram-based myocardial segmentation. The standard CT-MBF based on the 17-segment model was calculated using dynamic stress CTP data and deconvolution analysis. The CT-MBFsub was automatically analyzed by integrating the CT-MBF and Voronoi diagram-based myocardial segmentation analyses. The diagnostic performance of combined CT-MBFsub and Vsub assessment was determined using receiver operating characteristic analysis and compared with standard CT-MBF and CT-MBFsub. ResultsOf 117 vessels in 39 patients, 72 vessels were suspected of significant stenosis on CTA and 33 vessels had obstructive CAD on ICA and FFR. The sensitivity and specificity for identifying obstructive CAD were 67% and 82% for standard CT-MBF, 70% and 77% for CT-MBFsub, and 85% and 82% for combined CT-MBFsub and Vsub assessment. The area under the receiver operating characteristic curve of the combined CT-MBFsub and Vsub assessment was significantly higher than those of standard CT-MBF and CT-MBFsub (0.89 vs. 0.75, 0.77; p<0.05). ConclusionsThe Vsub may aid in increasing the diagnostic performance of CT-MBFsub for detecting obstructive CAD.

Dynamic CT perfusion imaging for type 2 endoleak assessment after endograft placement

Endovascular repair of abdominal aortic aneurysm is a widely performed treatment method due to its minimal invasiveness, reduced need for intensive care unit (ICU), shorter hospitalization and lower 30-day morbidity and mortality compared to open surgery. Endoleak is the drawback of this procedure and is considered the main culprit for re-interventions due to the risk of late aneurysm sac growth and rupture. Type 2 endoleak (T2EL) is the most common type of endoleak which is also the most controversial regarding its management. The aim of this paper is to investigate the potential of dynamic contrast-enhanced CT for the assessment of T2EL after endovascular aneurysm repair using qualitative and quantitative image analysis of the aneurysmal sac.

Dynamic Computed Tomography Perfusion for Diagnosis of Cellular Rejection after Heart Transplantation

Acute cellular rejection (ACR) is one of the most common complications in the first year after heart transplantation (HT). Endomyocardial biopsy (EMB) is the gold standard for ACR diagnosis, although it is neither very accurate nor reproducible, with false negative and false positive results reported. This pilot study aimed to determine the feasibility of the dynamic computed tomography perfusion (CTP) as an additional, non-invasive tool for rejection diagnosis after HT. The study group included 12 HT recipients and 20 controls who underwent CTP. ACR were detected on EMBs (ISHLT 2004). The results of CTP was represented as myocardial blood flow (MBF) and myocardial blood volume (MBV). Of 12 patients, 8 had ACR in EMB. CTP revealed either normal myocardium (Fig 1B) or irregular hypoperfused areas (Fig. 1A), localized mainly in the midwall layer of myocardium, which we called midwall patchy pattern (MPP). Within HT patients the number of segments with MPP correlated with the number of EMBs GRADE ≥1R (p<0.001). The ROC analysis showed that presence of >1 segment with MPP correlated significantly with GRADE ≥1R with 100% sensitivity and 96% specificity (AUC=0.974;p<0.001). In patients after HT, segments with MPP compared to the normal segments, differed significantly for MBF 116.3 [104.0-129.7] vs 179.7 [157.3-209.2] ml/100ml/min (p<0.0001) and MBV 13.2 [11.3-15.4] vs 18.5 [16.2-20.3] ml/100ml (p<0.0001). Dynamic CTP perfusion abnormalities in HT recipients may be correlated with cardiac allograft rejection, comprising potential non-invasive tissue biomarker for rejection. Our pilot study pioneer findings need confirmation in larger patient population. The study is funded by the Institute of Cardiology - grant 2.3/V/18 and by the National Science Centre, Poland - grant 2015/19/B/NZ5/03502.

Dynamic Volume Perfusion CT of the Foot in Critical Limb Ischemia: Response to Percutaneous Revascularization.

OBJECTIVE. The purpose of this study was to assess the reproducibility and validity of quantitative perfusion parameters derived from dynamic volume perfusion CT in patients with critical limb ischemia (CLI) and to evaluate perfusion parameter changes before and after endovascular revascularization. SUBJECTS AND METHODS. Patients with CLI referred for unilateral extremity endovascular arterial recanalization were enrolled in this study. CT examinations obtained 1-3 days before the procedure and then within 1 week after the treatment were evaluated at two reading sessions. Blood flow (BF), blood volume (BV), and time to peak (TTP) were measured on color-coded maps and compared statistically. Intraobserver agreement was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS. Endovascular treatment was technically successful for all 16 patients. The posttreatment BF and BV showed a statistically significant increase in both dermal and muscle areas (p < 0.05). The posttreatment TTP shortened at a statistically significant level (p < 0.05). In the 3-month clinical follow-up period, the limb salvage rate was 81% and the percentage change in BF and BV of patients with poor response to treatment had no statistically significant increase after treatment, consistent with the clinical assessment. The percentage change in BF and BV correlated well with the improvement of the clinical condition (r = 0.673-0.901). ICC values showed excellent agreement in the range of 0.95-0.98. CONCLUSION. As a reproducible method, dynamic volume perfusion CT of the foot may enable quantitative evaluation of the perfusion of soft tissues and also provide a novel approach to assessing response to endovascular recanalization in CLI.

Prognostic Value of Stress Dynamic Computed Tomography Perfusion With Computed Tomography Delayed Enhancement

ObjectivesThis study sought to evaluate the prognostic value of stress dynamic computed tomography (CT) perfusion (CTP) with CT delayed enhancement (CTDE) in patients with suspected or known coronary artery disease (CAD) and in subgroups of patients with stent, heavy calcification, or stenosis. BackgroundThe prognostic value of stress dynamic CTP with CTDE is unknown. MethodsParticipants were 540 patients with suspected or known CAD. Major adverse cardiac event(s) (MACE) consisted of cardiac death, nonfatal myocardial infarction, unstable angina, or hospitalization for congestive heart failure. Ischemic score was calculated by scoring the reduction of normalized myocardial blood flow in 16 segments excluding areas of myocardial scarring. Ischemic perfusion defect (IPD) was defined as Ischemic score ≥4. Scar score was also calculated by scoring the transmural extent of scarring in each segment on CTDE. ResultsDuring a median follow-up of 2.9 years, 43 MACEs occurred. By adding IPD to obstructive CAD (≥50% stenosis) on coronary CT angiography, the concordance index for predicting MACEs increased from 0.73 to 0.82 in patients with suspected CAD (p = 0.028) and from 0.61 to 0.73 in patients with known CAD (p = 0.004). IPD and scar score of ≥4 were independent predictors when adjusted for each other in patients with suspected (adjusted hazard ratios: 7.5 [p < 0.001] and 3.0 [p = 0.034], respectively) or known CAD (adjusted hazard ratios: 4.4 [p = 0.001] and 3.2 [p = 0.024], respectively). Patients with IPD had a higher annualized event rate than those without IPD in subgroups of those with stent (11.5% vs. 2.6%; p < 0.001), heavy calcification (13.3% vs. 3.1%; p < 0.001), 50% to 69% stenosis (8.8% vs. 1.0%; p < 0.001), or ≥70% stenosis (12.4% vs. 3.6%; p < 0.001). ConclusionsStress dynamic CTP with CTDE had incremental prognostic value over CT angiography in each group with suspected or known CAD and was prognostically useful in subgroups of patients with stent, heavy calcification, or obstructive CAD. IPD and myocardial scarring may play complementary roles in prognostic stratification.

Dynamic pulmonary CT perfusion using first-pass analysis technique with only two volume scans: Validation in a swine model.

PurposeTo evaluate the accuracy of a low-dose first-pass analysis (FPA) CT pulmonary perfusion technique in comparison to fluorescent microsphere measurement as the reference standard.MethodThe first-pass analysis CT perfusion technique was validated in six swine (41.7 ± 10.2 kg) for a total of 39 successful perfusion measurements. Different perfusion conditions were generated in each animal using serial balloon occlusions in the pulmonary artery. For each occlusion, over 20 contrast-enhanced CT images were acquired within one breath (320 x 0.5mm collimation, 100kVp, 200mA or 400mA, 350ms gantry rotation time). All volume scans were used for maximum slope model (MSM) perfusion measurement, but only two volume scans were used for the FPA measurement. Both MSM and FPA perfusion measurements were then compared to the reference fluorescent microsphere measurements.ResultsThe mean lung perfusion of MSM, FPA, and microsphere measurements were 6.21 ± 3.08 (p = 0.008), 6.59 ± 3.41 (p = 0.44) and 6.68 ± 3.89 ml/min/g, respectively. The MSM (PMSM) and FPA (PFPA) perfusion measurements were related to the corresponding reference microsphere measurement (PMIC) by PMSM = 0.51PMIC + 2.78 (r = 0.64) and PFPA = 0.79PMIC + 1.32 (r = 0.90). The root-mean-square-error for the MSM and FPA techniques were 3.09 and 1.72 ml/min/g, respectively. The root-mean-square-deviation for the MSM and FPA techniques were 2.38 and 1.50 ml/min/g, respectively. The CT dose index for MSM and FPA techniques were 138.7 and 8.4mGy, respectively.ConclusionsThe first-pass analysis technique can accurately measure regional pulmonary perfusion and has the potential to reduce the radiation dose associated with dynamic CT perfusion for assessment of pulmonary disease.

Abstract TP89: Absolute Cerebral Blood Flow Assessment With Novel Low-Dose Whole Brain Dynamic CT Perfusion Technique

Purpose: Existing CT perfusion (CTP) techniques are limited in accurate assessment of stroke. The purpose of this study is to validate a novel low-dose whole-brain first-pass analysis (FPA) technique as compared with gold standard microsphere measurement in a swine model. Materials and Methods: Contrast-enhanced CTP of 5 Yorkshire swine (55 ± 24 kg) was performed over 30 seconds at baseline and following incremental brain embolization. For each acquisition, gold standard fluorescent microspheres, IV contrast, and saline were injected (5 ml/s), followed by dynamic CTP imaging in a 320-slice CT scanner. Scan parameters were 320 x 0.5 mm collimation, 100 kVp, 200 mA, and 350 ms gantry rotation time. On average, 47 contrast-enhanced volume scans were acquired per acquisition to capture the entire time attenuation curve (TAC) of the carotid artery. For each acquisition, only two retrospectively selected volume scans were used to quantify brain perfusion with the low-dose FPA technique. Specifically, the first volume scan was selected at the base, while the second volume scan was selected at the peak of the TAC. Regional low-dose FPA CTP measurements from different lobes were then quantitatively compared to gold standard microsphere perfusion of corresponding tissue samples by using linear regression and Bland-Altman analysis. The CT dose index (CTDI) and dose-length product (DLP) of two-volume FPA technique were also determined. Results: Low-dose FPA perfusion measurements (P FPA ) were related to gold standard microsphere perfusion measurements (P MICRO ) by P FPA = 1.14 P MICRO - 0.01 (r = 0.93, p &lt; 0.01). The CTDI and DLP per two-volume FPA CTP were estimated to be 25.6 mGy and 409.6 mGy, respectively. Conclusion: Low dose FPA CTP technique was retrospectively validated in a swine model and has the potential to be used for accurate diagnostic assessment and follow up of patients with stroke and vasospasm.