Fully automatic model-based calcium segmentation and scoring in coronary CT angiography

Purpose

The paper presents new methods for automatic coronary calcium detection, segmentation and scoring in coronary CT angiography (cCTA) studies.

Methods

Calcium detection and segmentation are performed by modeling image intensity profiles of coronary arteries. The scoring algorithm is based on a simulated unenhanced calcium score (CS) CT image, constructed by virtually removing the contrast media from cCTA. The methods are implemented as part of a fully automatic system for CS assessment from cCTA.

Results

The system was tested in two independent clinical trials on 263 studies and demonstrated 0.95/0.91 correlation between the CS computed from cCTA and the standard Agatston score derived from unenhanced CS CT. The mean absolute percent difference (MAPD) of 36/39 % between the two scores lies within the error range of the standard CS CT (15–65 %).

Conclusions

High diagnostic performance, combined with the benefits of the fully automatic solution, suggests that the proposed technique can be used to eliminate the need in a separate CS CT scan as part of the cCTA examination, thus reducing the radiation exposure and simplifying the procedure.     

Radiation Dose in Coronary CT Angiography: How High is it and What Can be Done to Keep it Low?

Radiation dose reduction strategies in coronary CT angiography are paramount to ensure the lowest radiation exposure. This review provides basic knowledge of radiation physics. The technical background and the clinical implementations of various radiation dose-saving strategies for coronary CT angiography are discussed.     

Coronary CT angiography with low radiation dose

With the introduction of 64-slice CT and dual-source CT technology, coronary CT angiography (CCTA) has emerged as a useful diagnostic imaging modality for the noninvasive assessment of coronary heart disease. Recently, the risks associated with ionizing radiation on CT have raised serious concerns. The main concern of exposure to ionizing radiation is the potential risk of cancer. CCTA involves much higher radiation dose with the advances in the spatial and temporal resolution of cardiac CT. Currently, various dose-saving algorithms, such as ECG (electrocardiography)-based dose modulation, reduced tube voltage, and prospective ECG gating, high-pitch helical scanning are available to lower radiation exposure during cardiac CT. Therefore, careful selection of CT scanning protocols is needed to keep the radiation exposure ‘as low as reasonably achievable (ALARA)’. In this review we will discuss the radiation dose safety issues, the measurement of radiation dose and current use of dose-saving techniques in CCTA.     

Impact of a vendor-specific motion-correction algorithm on image quality,interpretability, and diagnostic performance of daily routine coronary CT angiography: influence of heart rate on the effect of motion-correction

To investigate the impact of a vendor-specific motion-correction algorithm on morphological assessment of coronary arteries using coronary CT angiography (cCTA) and to evaluate the influence of heart rate (HR) on the motion-correction effect of this algorithm. Eighty-four patients (mean age 56.3 ± 11.4 years; 53 males) were divided into two groups with a HR of ≥65 and <65 bpm during cCTA, respectively. Images were assigned quality scores (graded 1–4) on coronary segments. Interpretability was defined as a grade >1. Catheter angiography was used to determine the diagnostic accuracy of cCTA for detecting significant stenosis (≥50 %). We compared the image quality, interpretability and diagnostic accuracy between the standard and motion-correction reconstructions in both groups. The motion-correction reconstructions showed significantly (p < 0.05) higher image quality in the proximal and middle right coronary artery (RCA) in the low HR group (57.2 ± 5.0 bpm; n = 51) and proximal-to-distal RCA, posterior descending artery, and proximal and distal left circumflex artery in the high HR group (71.1 ± 4.6 bpm; n = 33). The per-segment interpretability was significantly higher using motion-correction algorithm in the middle RCA in the low HR group and in the proximal and middle RCA in high HR group. Overall, the image quality and interpretability were improved using motion-correction reconstructions in both groups (p < 0.05). Motion-correction reconstruction demonstrated higher (p < 0.05) diagnostic accuracy in 25 patients from both groups. Use of the motion-correction algorithm improves the overall image quality and interpretability of cCTA in both groups. However, it may be more beneficial to the patients with a higher HR.     

负荷动态CT心肌灌注结合冠状动脉CT血管成像对冠心病心肌缺血的诊断价值观察

目的探讨负荷动态CT心肌灌注结合冠状动脉CT血管成像对冠心病心肌缺血的诊断价值。方法选取2017年4月至2019年4月收治的96例冠心病心肌缺血患者为研究对象,随机将其等分为研究组和对照组,对照组采取冠状动脉CT血管成像检查,研究组采取负荷动态CT心肌灌注结合冠状动脉CT血管成像检查,比较两组使用造影剂剂量及放射剂量,斑块导致管腔狭窄比例、斑块长度以及诊断率。结果研究组患者造影剂剂量、放射剂量均明显低于对照组,差异有统计学意义(P<0.05);研究组患者斑块导致管腔狭窄比例、斑块长度、诊断率均明显高于对照组,差异有统计学意义(P<0.05)。结论冠心病心肌缺血患者联合应用冠状动脉CT血管成像与负荷动态CT心肌灌注,可在降低造影剂和放射剂量的情况下,明确冠状动脉狭窄和斑块病变情况,提高对疾病的临床诊断价值。     

Prospectively gated low-dose CCTA: 24 months experience in more than 2,000 clinical cases

Cardiac CT exams have recently come under increased scrutiny because of their relatively high radiation dose. The most effective way to lower the dose of coronary computed tomography angiography (CCTA) exams is with the use of prospective gating. This allows for a significant reduction in effective radiation dose when compared to retrospective ECG gating while image quality is maintained or improved. We reviewed data from 2,124 consecutive cardiac CT exams, including 1,978 CCTA’s and 146 CCTA’s post CABG. With effective heart rate control, prospective gating was used for 92.1% of the CCTAs and 83.2% of CCTAs following CABG. The prospectively gated CCTAs had a mean effective dose of 3.1 ± 1.5 mSv, CCTAs following CABG had a mean dose of 6.4 ± 2.3 mSv. We review our experience using prospective gating in specific areas to include patient selection, patient preparation, use of β- and calcium-channel-blockers for heart rate control, selection of gating technique and scan parameters, radiation dose, and post-processing techniques.     

Submillisievert imaging protocol using full reconstruction and advanced patient motion correction in 320-row area detector coronary CT angiography

Radiation exposure remains a concern in the use of coronary CT angiography (CCTA). Full reconstruction (Full) and reconstruction using advanced patient motion correction (APMC) could obtain a lower radiation dose using low tube current scanning in a 320-row Area Detector CT (320-ADCT). The radiation dose for an imaging protocol using Full and APMC in daily practice was estimated. A total of 209 patients who underwent CCTA in 1 rotation scanning with 100 kv and adaptive iterative dose reduction 3D in 320-ADCT were enrolled. Imaging protocols were classified into 3 groups based on estimated slow filling time: (1) slow filling time?≥?275 msec, Full with 30% of usual tube current (N?=?43)(Full30%mA) (2) 206.3 msec?≤?slow filling time?<?275 msec, APMC with 50% of usual tube current (N?=?48)(APMC50%mA); and (3) 137.5 msec?≤?slow filling time?<?206.3 msec, Half reconstruction with usual tube current (N?=?118)(Half100%mA). Radiation dose was estimated by the effective dose. The diagnostic accuracy of CCTA was compared with that of invasive coronary angiography in 28 patients. The effective doses of Full30%mA, APMC50%mA, and Half100%mA were 0.77?±?0.31, 1.30?±?0.85, and 1.98?±?0.68, respectively. Of 28 patients, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in vessel-based analyses were: Full30%mA, 66.7, 82.4, 80.0, 40.0, and 93.3%; APMC50%mA, 100.0, 80.0, 83.3, 50.05, and 100.0%; and Half100%mA, 90.9, 83.0, 86.3, 78.95, and 92.9%, respectively. An imaging protocol using Full30%mA and APMC50%mA was one of the methods how radiation dose could be reduced radiation dose maintained diagnostic accuracy compared to imaging using conventional Half100%mA.     

Responsible Use of Computed Tomography in the Evaluation of Coronary Artery Disease and Chest Pain

Many options are available to clinicians for the noninvasive evaluation of the cardiovascular system and patient concerns about chest discomfort. Cardiac computed tomography (CT) is a rapidly advancing field of noninvasive imaging. Computed tomography incorporates coronary artery calcium scoring, coronary angiography, ventricular functional analysis, and information about noncardiac thoracic anatomy. We searched the PubMed database and Google from inception to September 2009 for resources on the accuracy, risk, and predictive capacity of coronary artery calcium scoring and CT coronary angiography and have reviewed them herein. Cardiac CT provides diagnostic information comparable to echocardiography, nuclear myocardial perfusion imaging, positron emission tomography, and magnetic resonance imaging. A cardiac CT study can be completed in minutes. In patients with a nondiagnostic stress test result, cardiac CT can preclude the need for invasive angiography. Prognostic information portends excellent outcomes in patients with normal study results. Use of cardiac CT can reduce health care costs and length of emergency department stays for patients with chest pain. Cardiac CT examination provides clinically relevant information at a radiation dose similar to well-established technologies, such as nuclear myocardial perfusion imaging. Advances in technique can reduce radiation dose by 90%. With appropriate patient selection, cardiac CT can accurately diagnose heart disease, markedly decrease health care costs, and reliably predict clinical outcomes.CAC = coronary artery calcium; CAD = coronary artery disease; CT = computed tomography; CTA = coronary computed tomographic angiography; EBCT = electron beam CT; ED = emergency department; ICA = invasive coronary angiography; MDCT = multidetector helical CT; MI = myocardial infarction; MPI = myocardial perfusion imaging; NPV = negative predictive value; PPV = positive predictive valueCardiac computed tomography (CT) is a rapidly evolving technology for the noninvasive evaluation of the cardiovascular system. Numerous potential roles for cardiac CT have been developed recently, such as investigating anomalous coronary arteries, evaluating for pulmonary vein stenoses, and preparing for repeated coronary artery bypass grafting. However, the indication of most interest to the public and physicians is evaluating patients for native vessel coronary artery disease (CAD) using coronary artery calcium (CAC) scoring and coronary computed tomographic angiography (CTA).We searched the PubMed database and Google, from inception to September 2009, for keywords coronary artery calcium, coronary CT angiography, and radiation risk to identify information sources of interest. We also searched references in other review articles. From Google, we selected publications from trusted sources, such as the Food and Drug Administration and the National Academy of Sciences. From PubMed, we selected articles about test performance characteristics based on the quality of their methods, preferentially using randomized controlled trial data. We selected articles about clinical outcomes from randomized trials when available and from large cohorts as secondary sources. The purpose of this review is to summarize the recent data regarding accuracy, sensitivity, and specificity of CTA and the responsible use of cardiac CT.     

Low Radiation Dose Calcium Scoring: Evidence and Techniques

Coronary computed tomography (CT) allows for the acquisition of thin slices of the heart and coronary arteries, which can be used to detect and quantify coronary artery calcium (CAC), a marker of atherosclerotic cardiovascular disease. Despite the proven clinical value in cardiac risk prognostication, there remain concerns regarding radiation exposure from CAC CT scans. There have been several recent technical advancements that allow for significant radiation dose reduction in CAC scoring. This paper reviews the clinical utility and recent literature in low radiation dose CAC scoring.     

Prospective ECG-triggered sequential versus retrospective ECG-gated spiral CT: Pros and cons

Advancement of multidetector CT makes it possible to visualize the coronary arteries, as well as ventricular and valvular motion. However, the necessary radiation dose is higher than that associated with x-ray coronary angiography. Recently introduced prospective electrocardiograph (ECG)-triggered CT angiography (CTA), using conventional axial scan, can markedly reduce the radiation dose, while maintaining diagnostic performance, when appropriately applied in selected patients. The prospective ECG-triggered CTA is technically feasible in patients with low and stable heart rate. The indication for the CT examination should be exclusion of obstructive coronary disease, rather than analysis of ventricular and valvular function. The technique is most beneficial for young patients, especially young women, who are at low risk for significant coronary artery disease and for whom radiation dose is of great concern.     

Flash CT低管电压结合迭代重建技术在超重患者冠状动脉成像中的应用

目的探讨Flash CT低管电压结合迭代重建(IRIS)技术对改善超重患者冠状动脉成像图像质量及降低辐射剂量的价值。方法对100例体质量指数(BMI)为25～30kg/m2的患者行Flash CT检查,按扫描管电压随机化分成A(120kV)、B(100kV)两组,对B组图像经IRIS重建获得数据作为C组。测量主动脉根部、左冠状动脉及右冠状动脉起始部血管腔内CT值、噪声(SD),并计算SNR、CNR,记录有效辐射剂量(ED)。结果 3组图像优良率比较差异有统计学意义(χ2=7.604,P<0.05);3组血管腔强化CT值、噪声、SNR、CNR差异均有统计学意义(P均<0.05)。两两比较,血管腔内CT值B、C两组高于A组;B组噪声最大,CNR最低;C组SNR最高。A、C组ED分别为(8.6±1.3)mSv和(3.5±0.7)mSv,差异有统计学意义(t=-16.91,P<0.05)。结论对于超重患者运用低管电压结合IRIS技术进行Flash CT冠状动脉检查能够获得较好的图像质量,显著降低辐射剂量。     

Diagnostic value of coronary CT angiography with prospective ECG-gating in the diagnosis of coronary artery disease: a systematic review and meta-analysis

To perform a systematic review and meta-analysis of the diagnostic value of prospective ECG-gating coronary CT angiography in the diagnosis of coronary artery disease. A search of biomedical databases for English literature was performed to identify studies investigating the diagnostic value of 64- or more slice CT angiography with use of prospective ECG-gating in the diagnosis of coronary artery disease. Sensitivity, specificity, positive and negative predictive value estimates pooled across studies were tested using a fixed effects model. Fourteen studies met selection criteria for inclusion in the analysis. Pooled estimates and 95% confidence interval (CI) of sensitivity, specificity, positive and negative predictive value of prospective ECG-gating coronary CT angiography for diagnosis of significant coronary stenosis were 99% (95% CI: 98, 100%), 91% (95% CI: 88, 94%), 94% (95% CI: 91, 96%) and 99% (95% CI: 97, 100%), according to the patient-based assessment. The mean values of sensitivity, specificity, positive and negative predictive value of prospective ECG-gating coronary CT angiography were 95% (95% CI: 93, 96%), 95% (95% CI: 93, 95%), 88% (95% CI: 86, 90%), and 98% (95% CI: 97, 98%), according to vessel-based assessment; 92% (95% CI: 90, 93%), 97% (95% CI: 97, 98%), 84% (95% CI: 82, 86%), 99% (95% CI: 99, 99%), according to segment-based assessment, respectively. The mean effective dose was 3.3 mSv (95% CI: 2.3, 4.1 mSv) for the prospective ECG-gating coronary CT angiography. This analysis shows that for a predominantly male population with a high disease prevalence the use of coronary CT angiography with prospective ECG gating allows for a reduced radiation exposure without a sacrifice in diagnostic efficacy.     

Low-dose cardiac imaging: reducing exposure but not accuracy

Cardiac imaging techniques that use ionizing radiation have become an integral part of current cardiology practice. However, concern has arisen that ionizing radiation exposure, even at the low levels used for medical imaging, is associated with the risk of cancer. From a single diagnostic cardiac imaging procedure, such risks are low. On a population basis, however, malignancies become more likely on account of stochastic effects being more probable as the number of procedures performed increases. In light of this, and owing to professional and industrial commitment to the as low as reasonably achievable (ALARA) principle, over the last decade major strides have been made to reduce radiation dose in cardiac imaging. Dose-reduction strategies have been most pronounced in cardiac computed tomography. This was important since computed tomography has rapidly become a widely used diagnostic alternative to invasive coronary angiography, and initial protocols were associated with relatively high radiation exposures. Advances have also been made in nuclear cardiology and in invasive coronary angiography, and these reductions in patient exposure have all been achieved with maintenance of image quality and accuracy. Improvements in imaging camera technology, image acquisition protocols and image processing have lead to reductions in patient radiation exposure without compromising imaging diagnostic accuracy.     

The absence of coronary artery calcification does not rule out the presence of significant coronary artery disease in Asian patients with acute chest pain

The absence of coronary artery calcification (CAC) has been used to as an indication to rule out significant coronary artery disease (CAD). However, diagnostic usefulness of ‘zero calcium score criteria’ as a decision-making strategy to rule out significant CAD as the etiology of acute chest pain has not been studied in depth, especially in Asian ethnicity. We prospectively enrolled 136 Korean patients (58% men, 56 ± 13 years) who presented to the emergency department (ED) with acute chest pain and non-diagnostic ECG. All patients underwent 64-slice CT for calcium scoring and coronary CT angiography (cCTA). We investigated the association of CAC with the presence of ≥50% CAD on cCTA and with a final diagnosis of an acute coronary syndrome (ACS). Ninety-two patients out of 136 (68%) did not show detectable CAC, and 14 out of these 92 without CAC (15%) had ≥50% CAD on cCTA. Sensitivity, specificity, positive predictive value and negative predictive value of zero calcium score criteria for the detection of ≥50% CAD were 0.66 (95% confidence interval, 0.50–0.80), 0.83 (0.74–0.90), 0.64 (0.48–0.77), 0.85 (0.75–0.91), respectively. Patients who had ≥50% CAD without detectable CAC were younger (P = 0.001), and had a higher prevalence of smoking (P = 0.048) as compared to patients with a degree of CAC. Most of the patients with ≥50% CAD of non-calcified plaque were younger than 60 years of age (79%, 11/14), however, 3 of them were older than 60 years of age. Forty-five patients (33%) were subsequently diagnosed as having ACS, and 38% (17/45) of them had no CAC. Zero calcium score did not necessarily guarantee the absence of significant CAD, even in patients older than 60 years, in Asian ethnicity presenting to the ED with chest pain.     

320排CT前瞻性和回顾性心电门控冠状动脉成像:放射剂量、图像质量及诊断结果的对照观察

目的 比较前瞻性心电门控及回顾性心电门控320排CT冠状动脉成像的放射剂量、图像质量及诊断结果.方法 对临床拟诊冠心病、心率<65次/分的500例患者依次分别采用前瞻性及回顾性心电门控冠状动脉成像扫描方案,分为P组(前瞻组)和R组(回顾组),评价两组的辐射剂量、图像质量及诊断结果.结果 P组和R组各有3750(15×250)个冠状动脉节段,P组和R组冠状动脉节段管径太小(<1.5 mm)难于评估分别占3.49%(131/3750)、3.78%(142/3750),可评估节段占96.51%(3619/3750)、96.12%(3608/3750),差异无统计学意义(P>0.05);P组和R组的图像评分差异无统计学意义(P>0.05).P组和R组平均辐射剂量为(3.36±1.00)mSv、(13.46±2.30)mSv,P组平均射线剂量较R组降低75.04%,差异有统计学意义(P<0.01).P组的敏感度、特异度、阳性预测值及阴性预测值为93.22%、99.21%、91.64%、99.05%,R组的敏感性、特异性、阳性预测值及阴性预测值为94.55%、98.80%、95.86%、98.54%,差异无统计学意义(P>0.05).结论 320排CT前瞻性心电门控扫描方案较回顾性辐射剂量明显降低,但冠状动脉图像质量及诊断结果与回顾性心电门控扫描无明显差异.     

64层CT检测婴幼儿左侧冠状动脉起源于肺动脉

目的 探讨64层CT冠状动脉成像对婴幼儿左冠状动脉起源于肺动脉的诊断价值.方法 回顾性分析10例经手术证实左冠状动脉起源于肺动脉的婴幼儿,年龄5个月～2岁,体重5.5～10.0 kg.CT检查采用回顾性心电门控增强扫描,管电压80 kV,管电流150 mA,球管旋转速度0.35 s/转,层厚0.625 mm,螺距0.2.结果 CT扫描时患儿心率110～150次/分.图像质量均能满足诊断要求,辐射剂量1.11～1.62 mSv.所有患儿均为左侧冠状动脉起源于肺动脉,其中左冠状动脉开口于肺动脉右后窦及左后窦各4例,开口于肺动脉窦远侧右后壁及下壁各1例.结论 64层CT冠状动脉成像可在低辐射剂量条件下准确显示婴幼儿左侧冠状动脉起源于肺动脉的开口及走行.     

Effect of dose reduction on image quality and diagnostic performance in coronary computed tomography angiography

To evaluate the effect of radiation dose reduction on image quality and diagnostic accuracy of coronary computed tomography (CT) angiography. Coronary CT angiography studies of 40 patients with (n = 20) and without (n = 20) significant (≥50 %) stenosis were included (26 male, 14 female, 57 ± 11 years). In addition to the original clinical reconstruction (100 % dose), simulated images were created that correspond to 50, 25 and 12.5 % of the original dose. Image quality and diagnostic performance in identifying significant stenosis were determined. Receiver–operator-characteristics analysis was used to assess diagnostic accuracy at different dose levels. The identification of patients with significant stenosis decreased consistently at doses of 50, 25 and 12.5 of the regular clinical acquisition (100 %). The effect was relatively weak at 50 % dose, and was strong at dose levels of 25 and 12.5 %. At lower doses a steady increase was observed for false negative findings. The number of coronary artery segments that were rated as diagnostic decreased gradually with dose, this was most prominent for smaller segments. The area-under-the-curve (AUC) was 0.90 (p = 0.4) at 50 % dose; accuracy decreased significantly with 25 % (AUC 0.70) and 12.5 % dose (AUC 0.60) (p < 0.0001), with underestimation of patients having significant stenosis. The clinical acquisition protocol for evaluation of coronary artery stenosis with CT angiography represents a good balance between image quality and patient dose. A potential for a modest (<50 %) reduction of tube current might exist. However, more substantial reduction of tube current will reduce diagnostic performance of coronary CT angiography substantially.     

Coronary CT Angiography in Acute Chest Pain Syndromes

In the United States alone, nearly 6 million patients present annually to emergency departments with complaints of chest pain suspicious for acute coronary ischemia. Acute chest pain represents a clinical as well as economic challenge, often resulting in elaborate, time-consuming, and expensive evaluation to avoid litigation related to missed diagnosis of acute coronary syndromes (ACS). Coronary CT angiography (CCTA) is a rapid, widely available technique with promising initial results for use in the emergency department in patients with acute chest pain. Due to its high accuracy and sensitivity, CCTA can aid in safe, rapid, and cost-efficient triage of these patients. Latest-generation scanners and novel acquisition strategies demonstrate significant radiation dose reduction. Additional applications of plaque characterization and perfusion imaging hold promise in providing incremental data in patients with suspected ACS.     

Is Dual-Axis Rotational Coronary Angiography Radiation Dose Reduction Achievable in a Population with 100% Suspected Coronary Artery Disease? A Randomized Trial

BackgroundPrevious studies have shown a reduction in radiation dose and contrast volume using dual-axis rotational coronary angiography (DARCA), but this has not been replicated in a population with 100% coronary artery disease (CAD).ObjectiveTo find if DARCA dose reduction is achievable in this population, we sought to compare the radiation dose, contrast volume, and procedure time between DARCA and conventional coronary angiography (CCA) techniques in a setting characterized by a prevalence of 100% suspected coronary artery disease.MethodsAn all-comer, prospective, randomized, open-label trial was conducted. Cine acquisition dose–area product (DAP), cumulative air kerma (AK), effective dose (E), fluoroscopic time, contrast volume, AK, cine acquisition DAP (CADAP), fluoroscopic DAP (F-DAP), and total DAP were compared between DARCA and CCA groups.ResultsWe included 503 consecutive patients with suspected CAD. 252 were assigned to DARCA and 251 to CCA. Stable coronary artery disease was reported in 465 cases and non-ST elevation acute coronary syndrome in 38. Mean age: 61.88 ± 11.2 years, male gender 70.2%. DARCA arm patients showed lower total E dose (6.85 [4.55–10.83] vs. 7.91 [5.58–11.94] Sv; P = .0023), and cine E (3.00 [2.00–4.00] vs. 4.00 [3.00–5.00] Sv; P < .0001). Total DAP was also lower (40.3 [26.8–63.7] vs. 46.5 [32.8–70.2] Gycm²; P = .0023), as a consequence of a lower CADAP (16.3 [10.5–22.9] vs. 23.4 [17.4–32.0] Gycm²; P < .0001), with lower AK (367 [248–1497] vs. 497 [381–1827] mGy; P < .0001), with less contrast medium used (90 [60.0–106.0] vs. 100 [75.0–120.0] mL; P = .014).ConclusionIn a population with 100% suspected coronary artery disease, DARCA provides accurate information required in CAD, is safe, and results in a significant decrease in contrast material volume and radiation dose compared with CCA. The required extra projections did not neutralize the DARCA radiation dose and contrast volume reduction achievements.     

冠状动脉CT低剂量血管成像的研究进展

冠状动脉CT低剂量血管成像在不同研究间相差很大,以患者为中心的剂量优化成为一个重要领域。本文对近年有关冠状动脉CT血管成像低剂量扫描的进展进行综述。