Calcified plaque may be missed on coronary CT angiography (cCTA) with highly concentrated iodinated contrast material (CM) at low kV settings. We analyzed the impact of different iodine density CM at varying tube potential for the assessment of calcified plaques on cCTA images.
METHOD AND MATERIALS164 consecutive patients with suspected coronary artery disease underwent non-enhanced calcium scoring (CaSc) at 120 kV followed by cCTA with topogram-based automated kV selection on third- or second-generation dual-source CT. Based on prior observations 37 patients were injected diluted CM with a resulting iodine concentration of 280 mg/ml (group1) between September 2015 and March 2016 whereas 127 patients were injected undiluted CM with an concentration of 400 mgI/ml (group2). Amount (50 ml) and flow rate (5 ml/s) were kept constant. The sensitivity of cCTA for detecting calcified plaques was evaluated with CaSc at 120 kV serving as the reference.
RESULTS97 patients (59%) had calcified plaques on CaSc, 78 patients of group 2 and 19 patients of group 1. The overall sensitivity of cCTA for detection of calcified plaques was 79% in group 1 and 73% in group 2. Sensitivity for patients examined at 70 kV was significantly higher with diluted CM (70% vs. 57%). There was no significant difference in sensitivity at 100 and 120 kV in both groups (100% and 82% in group 1 and 2, respectively). The overall median luminal contrast density was 389 HU with diluted CM and 503 HU with undiluted CM. At 70 kV, values were at 463 HU and 655 HU, at 100 kV they were at 197 HU and 365 HU with diluted vs. undiluted CM.
CONCLUSIONThe combination of highly concentrated CM and 70 kV tube potential reduces the detectability of calcified plaques. In order to preserve reliable information on relevant calcifications, cCTA at 70 kV should be performed with CM with lower iodine concentration. If undiluted CM is used, 100 kV tube potential should preferably be chosen.
CLINICAL RELEVANCE/APPLICATIONPatients may benefit from both low radiation and contrast exposure when examined at 70 kV cCTA. However, 100 kV protocols yield higher sensitivity or reliable calcified plaque visualization.
The aim of this study was to compare transcatheter coronary artery fistula (CAF) closure (TC) with surgery closure (SC).
METHOD AND MATERIALSFrom 2011 to 2015, 21 patients (age range from 18 to 76 years, 11 males) were diagnosed CAF in our center. Twelve of them were underwent transcatheter closure, 9 patients were attempted to closure in surgery. Hemodynamic evaluation and coronary artery angiography had been carried out before procedures.
RESULTSNine procedures in TC group were successful, 3 failures due to inabilities to cannulate the distal of lesion. There was no death in TC group. One patient in SC group had procedure related death. Procedure room time ( 103 ± 89 min vs. 305 ± 118 min, p < 0.001 ), intensive care unit time ( 0 hour vs. 24 hours, p < 0.001 ), length of stay ( 5 days ± 15 days, p < 0.001 ) were significantly less in TC group. Two cases of residual shunts were detected in immediate angiography of TC group. One of them turned to a significant recanalization, and a second intervention was performed. No recanalization was found in SC during follow-ups. Follow-up was obtained in all the patients. At a median time of 17.5 months, there was no significant difference in survival ( TC, 100% vs. SC, 94.4%, p = 0.471 ).
CONCLUSIONBoth transcatheter and surgery closure can achieve satisfactory results of CAF. However, the procedure time, length of stay and resource use was significant lower in TC group.
CLINICAL RELEVANCE/APPLICATIONCoronary artery fistula intervention is a safe and feasible method, and should be considered firstly if the anatomic condition was appropriate.
To achieve a consistent enhancement in coronary CT angiography (CCTA) by implementing a contrast injection protocol with adjusted iodine concentration based on patient habitus and kVp.
METHOD AND MATERIALSRetrospective data from 80 consecutive patients (group 1) scanned on a Revolution CT (GE Healthcare) with one-heartbeat automated triggering, 100 kVp (N=74) or 120 kVp (N = 6), noise index = 25 and standard iodine dose (70 ml of 370 mg I / ml, 350 mg I / ml or 320 mg I / ml) was collected, using DoseWatch (GE Healthcare). The optimal correlation between arterial enhancement (HU) and body habitus normalized to total iodine dose (TID) was determined by considering following parameters: weight, Body Mass Index (BMI), Body Surface Area (BSA), Lean Body Mass (LBM) and Fat Free Mass (FFM). From the parameter giving the best correlation, a model for optimal contrast concentration to achieve a target enhancement value of 550 HUtarget was determined and prospectively applied to 62 patients (N=1 at 80 kVp, N=55 at 100 kVp and N=6 at 120 kVp) undergoing a CCTA exam (group 2). Personalized iodine concentration was administered by parallel mixing of iodine with saline on a dual-head power injector (Nemoto-Kyorindo, Japan). Enhancement was compared between group 1 and 2 (Mann-Whitney U- test) and homogeneity of variances was tested (Levene’s test).
RESULTSCompared to other body habitus parameters (R² range 0.1 – 0.5), Free Mass (FFM) showed the strongest correlation (R² = 0.5) with enhancement. Following contrast injection model was established for 100 kVp: TID = (HUtarget - 237)*FFM/946; for 120 and 80 kVp TID should be scaled by 1.22 and 0.77 respectively. With the modified protocol, variance (standard deviation) reduced from 102 HU to 67 HU (p < 0.01). The mean enhancement 506 HU was lower than the target 550 HU (p <0.01).
CONCLUSIONAn injection protocol with contrast concentration adapted to body habitus, iodine concentration and kVp improves patient-to-patient CT value uniformity.
CLINICAL RELEVANCE/APPLICATIONPersonalizing the iodine injection protocol for CCTA homogenizes image quality in terms of contrast enhancement for an easier interpretation and correlation of images.
Cardiac CT is an important and indispensable method for the assessment of coronary artery stent patency. However, when the CT images are reconstructed with filtered back projection (FBP) or hybrid iterative reconstruction (IR) the diagnosis of in-stent restenosis is occasionally difficult due to blooming- and streak artifact. A new type of full IR algorithm (forward projected model-based iterative reconstruction solution; FIRST, Toshiba Medical Systems) improves the spatial resolution and decreases the artifacts. We compared the image quality of coronary artery stent between the CT images reconstructed with FIRST and with hybrid IR (AIDR 3D, Toshiba).
METHOD AND MATERIALSWe prospectively enrolled thirty patients (11 women, mean age 71.4 ± 8.6 years) who had 34 coronary stents. They underwent coronary CT angiography (CTA) using a 320-slice CT scanner. Images were reconstructed with AIDR 3D (standard setting) using a medium soft-tissue convolution kernel and with FIRST (cardiac setting). For each of the two reconstruction methods we generated attenuation profiles and measured the width of the 10-90% edge rise distance (ERD) at the boundary and determined a slope of linear function as follow: Slope = (CT90% - CT10%) / ERD. Two radiologists visually evaluated the image quality based on the blooming artifacts from the stent using a 4-point scale ranging from 1 = impaired diagnostic information to 4 = minimal or absent. The ERD and slope between the two reconstruction methods were compared using the paired t-test, image quality scores with the Wilcoxon signed-rank test.
RESULTSThere was no significant difference in the mean ERD between the two reconstruction methods (0.7 ± 0.2 mm vs.0.6 ± 0.2 mm; p = 0.14). The mean slope on FIRST images was higher than AIDR 3D (378.7 ± 149.5 vs.195.2 ± 116.6; p < 0.001). The mean image quality score for AIDR 3D and FIRST images were 2.7 and 3.6, respectively; the difference was also significant (p < 0.05).
CONCLUSIONAs the use of the FIRST improved image quality of the coronary artery stent at coronary CTA, it may improve the detection of in-stent restenosis compared to the conventional method.
CLINICAL RELEVANCE/APPLICATIONThe diagnostic performance could be improved when FIRST is used for the detection of in-stent restenosis compared to the conventional method.
Cardiologists currently catheterize all three major coronary arteries as standard of care in patients with coronary artery disease (CAD), even though previously performed coronary CT angiography (cCTA) showed only one- or two-vessel disease with no or non-relevant atherosclerosis in the other vessels. We investigated the potential reduction of patient exposure during invasive coronary catheterization (ICA) if the procedure had only been directed to the vessel of interest by utilizing information of the CT report.
METHOD AND MATERIALSDose reports of 52 patients who were referred to ICA because of at least one moderate or severe stenosis on cCTA were retrospectively included. There was no selection of patients based on CT image quality. The dose-area product (DAP) was documented separately for the left (LAD, CX) and the right coronary artery (RCA) by summing up the single DAPs for each projection. The study population was further subdivided according to the procedure performed: coronary angioplasty/stent insertion of LCA (group 1) or RCA (group 2) only, or of both vessels (group 3), or no intervention (group 4). Furthermore, patients with no intervention but subsequent coronary artery bypass grafting were included (group 5).
RESULTSAll 36 arteries (LCA or RCA) classified as non-significantly diseased on cCTA out of 104 coronary arteries (35%) were confirmed by ICA with no further intervention. Half of the study population could have benefit from reduced exposure if catheterization had been directly guided to the vessel of interest as described on cCTA. Potential mean relative DAP reduction were as follows: group 1 (n = 14) 10.5%; group 2 (n = 1) 43.4%; group 3 (n = 10) 0%; group 4 (n = 24) 25.7%; group 5 (n = 3) 0%. However, calcium blooming artifacts caused overestimation of stenosis severity in 16/104 (15%) vessels on cCTA with subsequent need for diagnostic ICA.
CONCLUSIONDirecting ICA to the vessel of disease as described on cCTA would be safe and reduce patient exposure in the cath lab substantially, especially for patients with one-vessel disease. Calcified plaques remain a limitation on cCTA leading to unnecessary ICA referrals.
CLINICAL RELEVANCE/APPLICATIONcCTA can guide cardiologists directly to the vessel of interest for coronary intervention with substantial dose reduction for the invasive procedure, making coronary catheterization safer and faster for patients.
To investigate the image quality (IQ) and diagnostic value of single-phase coronary artery CT angiography (CCTA) image from stress dynamic myocardial CT perfusion (CTP) scan on the third-generation dual-source CT (DSCT).
METHOD AND MATERIALSNineteen consecutive symptomatic patients (13men and 6women; 58.5±10.3years) who underwent CCTA and diagnosed with at least one moderate stenosis (degree≧50%) lesion of the three main coronary arteries were recruited. The patients were scanned with prospective automatic CARE-kV selection ATP-stress dynamic myocardial CTP examination (44ml contrast media＆60ml saline at 5.5ml/s) on a third-generation DSCT with data acquisition window at the end systole. The single-phase CCTA image with the best enhancement of coronary arteries in the process of CTP was selected for reconstruction and measurement. The quantitative (CT value, background noise, signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) and qualitative (Likert four-point grading scale) IQ results as well as the diagnostic value (detection of coronary artery stenosis lesion) were compared with that of the former CCTA examination images.
RESULTSThere were no significant difference in quantitative (CT values, noise, SNR and CNR) IQ between the CTP-CCTA and former CCTA (p>0.05), except for the SNR of aorta root (14.70±2.10 and 18.67±4.85, p<0.05). No significant difference in qualitative IQ has been found between CTP-CCTAand former CTA (score: 1.38±0.60 and 1.47±0.61, p>0.05). CTP-CCTA detect stenosis in good correlation with former CCTA (97%, 99 of 102), especially for moderate-severe stenosis (100%, 53 of 53). The patients’mean heart rate (HR) during stress CTP (83.92±11.03bpm) was much higher than that of the former CCTA (68.91±12.81bpm) scan (p=0.005). The mean effective radiation dose (ED) of CTP is 4.48±1.87mSv.
CONCLUSIONThe IQ and diagnostic value of single-phase CCTA image from stress dynamic myocardial CTP on the third-generation dual-source CT system was great and one myocardial CTP scan is potentially feasible to replace the CTP＆CTA examination.
CLINICAL RELEVANCE/APPLICATIONThe single-phase CCTA image derived from CTP at the third-generation DSCT system is able to replace the CCTA scan for symptomatic patients with suspected or known CAD, which enable the greatly reduction of ED for patients and create highest possibilities for one-stop cardiac CT examination within one myocardial CTP scan.