Maximizing dose reductions with cardiac CT

Feasibility of the Big 5-Jena eCS Protocol : First Experience Implementing a New Extended CT Protocol in the Initial Diagnostics of Ischemic Stroke

PURPOSE

The most common protocols in the initial diagnostic of acute ischemic stroke do not assess cardiogenic or aortic causes of embolism. These are usually evaluated later by transthoracic (TTE) or transesophageal (TEE) echocardiography. This study aimed to evaluate the feasibility of a diagnostic tool for thoracic cardiovascular thrombi according to the first experience with a new extended cardio-stroke protocol (Big 5-Jena eCS protocol) in acute stroke patients.

METHODS

Retrospective analyses of the tomography scans database of the Jena University Hospital were performed. We included a total of 67 patients in the feasibility analyses, based on the evaluation of three outcomes.

RESULTS

Primary outcome: the Big 5-Jena eCS protocol was able to detect thoracic cardiovascular thrombi in a total of 20 patients in different locations including the arch of the aorta, the aortic valve, the left atrium, the left atrial appendage, the left ventricle, and the pulmonary arteries. Secondary outcome: implementating the protocol did not result in a significant elevation of the radiation exposure compared to traditional protocols. Tertiary outcome: the new protocol identified seven cases that were considered negative by echocardiography.

CONCLUSION

The implementation of an extended cardio-stroke protocol is feasible, no significantly time-consuming, acquiring assessable imaging, and maintaining radiation exposure acceptable. The Big 5-Jena eCS protocol was also able to detect some thrombi not reported by TTE or TEE; however, due to our data's explorative character, a conclusive comparison with cardiac ultrasound is not possible. A prospective pilot study and clinical trials should be conducted to assess the diagnostic accuracy of this protocol compared to echocardiography and determine the potential impact on diagnostic and treatment decisions.

Protocol Optimization and Implementation of Dual-Energy and Dual-Source Computed Tomography in Clinical Practice: Field of View, Speed, or Material Separation?

Clinical use of dual-energy computed tomography (DECT) and dual-source computed tomography (DSCT) has been well established for more than a decade. Improved software and decreased postprocessing time have increased the advantages and availability of DECT and DSCT imaging. In this article, we will provide a practical guide for implementation of DECT and DSCT in clinical practice and discuss automated processing and selection of CT protocols in neurologic, cardiothoracic, vascular, body, and musculoskeletal imaging.

Preoperative Physiology, Imaging, and Management of Coarctation of Aorta in Children

Coarctation of the aorta (CoA) is a narrowing of the proximal thoracic aorta typically located at the junction of the aorta with the ductus arteriosus. While it is a simple lesion to understand, considerable variation exists in the anatomy and pathophysiology, leading to varied clinical presentation, management options, and prognosis. On the one hand critical CoA manifests in the neonatal period as a duct-dependent lesion, while less severe forms of obstruction present later in childhood or adulthood as hypertension or incidentally noted precordial murmurs. While transthoracic echocardiography is usually adequate, older children and adults may need more advanced imaging modalities like computed tomography and magnetic resonance imaging prior to intervention. Depending on the type of lesion, management options currently available include surgery and percutaneous balloon angioplasty and stenting. Even after successful interventions, these patients need life-long surveillance for residual aortic obstruction and systemic hypertension with variable long-term clinical outcomes.

Optimizing Cardiac CT Protocols for Comprehensive Acquisition Prior to Percutaneous MV and TV Repair/Replacement

Clinical trials of transcatheter mitral valve and tricuspid valve repair and replacement devices have begun in earnest, with the ultimate goal of providing definitive, nonsurgical treatment for the millions of patients with severe, symptomatic regurgitation, many of whom are too high risk or inoperable for a surgical approach. Computed tomography (CT) angiography offers the potential for detailed anatomic assessment in this patient population, but its optimal implementation for patients with mitral and tricuspid disease requires patient-centered protocol specification reflecting the goal of the scan, an understanding of complex anatomy and pathophysiology, and particulars of CT scanner capabilities. In this paper, the need for new interventional approaches to mitral and tricuspid valve disease is discussed, followed by a detailed review of how to perform a high-quality CT angiography examination, taking into consideration scanner- and patient-specific variables when preparing a pre-mitral or tricuspid protocol. The many possible clinical challenges affecting the performance of cardiac and vascular CT angiography for pre-procedure mitral and tricuspid repair/replacement are reviewed and specific tips, trouble-shooting approaches, and recommendations are provided for how to conduct the best-quality study, be it at an experienced imaging center with the most advanced scanner or at a novice center using an earlier generation CT platform.

[Influence of Bowtie Filter and Patient Positioning on In-plane Dose Distribution and Image Quality in ECG-gated CT]

In electrocardiographic (ECG)-gated computed tomography (CT) for diagnosis of cardiac diseases, radiation dose and image quality are optimized by limiting field of view (FOV) and centering on the heart. However, it is necessary to set wide FOV with large bowtie filter depending on patient positioning or various diagnoses such as aortic diseases. The purpose of this study is to clarify influence of bowtie filter and patient positioning on in-plane dose distribution, organ-absorbed dose, image quality in ECG-gated CT. In-plane dose distribution and organ-absorbed dose were evaluated with radio photoluminescence glass dosimeters, and signal-to-noise ratio (SNR) were measured for evaluation of image quality. The bowtie filter was used small (S) and large (L). With automatic exposure control, volume computed tomography dose index was 55.3 mGy at S and 71.8 mGy at L. The phantom was positioned on the heart of phantom (Heart) and the center of phantom (Body). In Heart-L compared with Heart-S, organ-absorbed dose was 1.29 times at breasts. In Heart-S compared with Body-S, in-plane dose distribution was increased 25% at left anterior and decreased 20% at right posterior. In SNR, S and L were decreased from 50 mm off-center. To set appropriate bowtie filter and positioning was reduced radiation dose and improved image quality in ECG-gated CT.

Radiation exposure and coronary artery calcium scans in the society for heart attack prevention and eradication cohort

Coronary artery calcium (CAC) scoring is used in asymptomatic patients to improve their clinically predicted risk for future cardiovascular events. Current CT protocols seek to reduce radiation exposure without diminishing image quality. Reported radiation exposure remains widely variable (0.8-5 mSv) depending on the type of protocol. In this study, we report the radiation exposure of CAC scoring from the Society for Heart Attack Prevention and Eradication (SHAPE) early detection program cohort sites, which spanned multiple centers using 64-MDCT (multi-detector computed tomography) scanners. We reviewed radiation exposure in milliSieverts (mSv) for 82,214 participants from the SHAPE early detection program cohort who underwent CAC scoring. This occurred over a 2.5-year period (2012-2014) divided among 33 sites in 7 countries with four different types 64-MDCT scanners. The effective radiation dose was reported as mSv. Mean radiation dosing amongst all 82,214 participants was 1.03 mSv, a median dose of 0.94 mSv. The mean radiation dose ranged from 0.76 to 1.31 mSv across the 33 sites involved with the SHAPE program cohort. Subgroup analysis by age, gender or body mass index (BMI) less than 30 kg/m² showed no variability. Radiation dose in patients with BMI > 30 kg/m² were significantly greater than other subgroups (µ = 1.96 mSv, p < 0.001). The use of 64-MDCT scanners and protocols provide the effective radiation dose for CAC scoring, which is approximately 1 mSv. This is consistently lower than previously reported for CAC scanning, regardless of scanner type, age or gender. In contrast, a greater BMI influenced mean radiation doses.

Ultra-low-dose CT coronary angiography using 128-slice dual source CT with low concentration contrast agent: initial experience

PURPOSE

To optimize and evaluate an ultra-low-dose (ULD) technique for CT coronary angiography (CTCA).

MATERIALS AND METHODS

Eighty-two patients were randomly divided into two groups. ULD and routine CTCA were performed in groups A and B. Image quality, radiation dose and contrast agent were evaluated.

RESULTS

The effective dose (ED) was 0.20 ± 0.01 mSv for the ULD technique, a decrease of 87% (t = - 21.182, P < 0.001) compared with the control group. The total iodine content was 8.10 ± 0 g, a decrease of 62% (t = - 73.458, P < 0.001) compared with 21.10 ± 1.15 g for the control group. The assessment rates for both groups were the same (99.26 vs 99.64%, χ ²  = 0.727, P = 0.394). The contrast-to-noise ratio was 19.31 ± 7.95 for group A and 20.73 ± 5.07 for group B: the difference was not statistically significant (t = - 1.678, P = 0.095).

CONCLUSION

Using an ultra-low radiation dose and contrast agent technique, while maintaining an assessable image and improving the safety of the medical examination, was a feasible and reliable method for CTCA.

Coronary calcium scans and radiation exposure in the multi-ethnic study of atherosclerosis

With the increasing use of coronary artery calcium (CAC) scoring to risk stratify asymptomatic patients for future cardiovascular events, there have been concerns raised regarding the theoretical risk of radiation exposure to this potentially large patient population. Newer CT protocols have sought to reduce radiation exposure without compromising image quality, but the reported radiation exposures in the literature remains widely variable (0.7-10.5 mSv). In this study, we report the radiation exposure of calcium scoring from our MESA cohort across several modern CT scanners with the aim of clarifying the radiation exposure of this imaging modality. To evaluate the mean effective doses of radiation, using dose length product, utilized for coronary artery calcium scoring in the MESA cohort, in an effort to understand estimated population quantity effective dose using individual measurements of scanner radiation output using current CT scanners. We reviewed effective dose in milliSieverts (mSv) for 3442 participants from the MESA cohort undergoing coronary artery calcium scoring, divided over six sites with four different modern CT scanners (Siemens64, Siemens Somatom Definition, GE64, and Toshiba 320). For effective dose calculation (milliSieverts, mSv), we multiplied the dose length product by conversion factor k (0.014). The mean effective dose amongst all participants was 1.05 mSv, a median dose of 0.95 mSV. The mean effective dose ranged from 0.74 to 1.26 across the six centers involved with the MESA cohort. The Siemens Somatom Definition scanner had effective dose of 0.53 (n = 123), Siemens 64 with 0.97 (n = 1684), GE 64 with 1.16 (n = 1219), and Toshiba 320 with 1.26 mSv (n = 416). Subgroup analysis by BMI, age, and gender showed no variability between scanners, gender, ages 45-74 years old, or BMI less than 30 kg/m(2). Subjects over age 75 yo had a mean effective dose of 1.29 ± 0.31 mSv, while the <75 yo subgroup was 0.78 ± 0.09 mSv (p < 0.05). Effective doses in subjects with BMI > 40 kg/m(2) was significantly greater than other subgroups, with mean dose of 1.47 ± 0.51 mSv (p < 0.01). Using contemporary CT scanners and protocols, the effective dose for coronary artery calcium is approximately 1 mSv, an estimate which is consistently lower than previously reported for CAC scanning, regardless of age, gender, and body mass index.

CT and MRI of aortic coarctation: pre- and postsurgical findings

OBJECTIVE. The purpose of this article is to summarize the roles of CT and MRI in the diagnosis and follow-up of patients with aortic coarctation. CONCLUSION. Aortic coarctation is a common congenital heart disease accounting for approximately 6-8% of congenital heart defects. Despite its deceptively simple anatomic presentation, it is a complex medical problem with several associated anatomic and physiologic abnormalities. CT and MRI may provide very accurate information of the coarctation anatomy and other associated cardiac abnormalities.

Comparison of transesophageal echocardiography versus computed tomography for detection of left atrial appendage filling defect (thrombus)

Patients with atrial fibrillation, who are referred for radiofrequency pulmonary vein antral isolation, frequently undergo transesophageal echocardiography (TEE) to detect and/or exclude left atrial or left atrial appendage (LAA) thrombus and cardiac computed tomographic angiography (CCTA) to define and/or evaluate left atrial and pulmonary venous anatomy. Previous studies have reported CCTA to have high sensitivity and negative predictive value (NPV) for detecting thrombus in the LAA. Previous studies determining an optimal LAA/ascending aorta (AA) Hounsfield unit (HU) density ratio for detection of LAA thrombus have been small, with limited numbers of thrombi. We thus sought to determine both the optimal cutoff for LAA HU density and LAA/AA HU density ratio in detecting LAA thrombus compared with TEE in a multicenter population. We included 84 patients who had undergone CCTA and TEE. LAA was evaluated by 64-row CCTA qualitatively (visual filling defect) and quantitatively (measurement of LAA HU density and LAA/AA HU density ratio), using a 1-cm area of interest in the same axial plane. Results were compared with TEE visualization of thrombus or spontaneous echo contrast. Qualitative identification of thrombus in LAA by CCTA compared with TEE detection of thrombus had a sensitivity of 100%, a specificity of 77.9%, a positive predictive value (PPV) of 51.6%, an NPV of 100%, and a total accuracy of 82.1%. The optimal LAA HU density cutoff for thrombus detection was 119 with a sensitivity of 88%, a specificity of 86%, PPV 56%, and an area under the curve of 0.923 (p = 0.0004). The optimal LAA/aorta HU ratio was 0.242 with a sensitivity of 87%, a specificity of 88%, a PPV of 64%, and an area under the curve of 0.921 (p = 0.0011). There is no significant difference (p = 0.72) between both areas under the curve, and both measurements improved the specificity and PPV compared with qualitative measures. Multidetector computed tomography is an imaging technique that can exclude LAA thrombus with very high NPV. Quantitative measurement of LAA HU density (cutoff 119) or LAA/aorta HU density ratio (cutoff 0.242) improves accuracy of positively detecting LAA thrombus. This technique is especially useful when delayed scanning is not performed and LAA is found incidentally after the patient scanning is complete.

Low-dose CT in clinical diagnostics

INTRODUCTION

Computed tomography (CT) has become key for patient management due to its outstanding capabilities for detecting disease processes and assessing treatment response, which has led to expansion in CT imaging for diagnostic and image-guided therapeutic interventions. Despite these benefits, the growing use of CT has raised concerns as radiation risks associated with radiation exposure.

AREAS COVERED

The purpose of this article is to familiarize the reader with fundamental concepts of dose metrics for assessing radiation exposure and weighting radiation-associated risks. The article also discusses general approaches for reducing radiation dose while preserving diagnostic quality. The authors provide additional insight for undertaking protocol optimization, customizing scanning techniques based on the patients' clinical scenario and demographics. Supplemental strategies are postulated using more advanced post-processing techniques for achieving further dose improvements.

EXPERT OPINION

The technologic offerings of CT are integral to modern medicine and its role will continue to evolve. Although, the estimated risks from low levels of radiation of a single CT exam are uncertain, it is prudent to minimize the dose from CT by applying common sense solutions and using other simple strategies as well as exploiting technologic innovations. These efforts will enable us to take advantage of all the clinical benefits of CT while minimizing the likelihood of harm to patients.

Economic analysis of the use of coronary calcium scoring as an alternative to stress ECG in the non-invasive diagnosis of coronary artery disease

OBJECTIVE

To conduct an economic analysis (EA) of coronary calcium scoring (CCS) using a 0 score, as alternative to stress electrocardiography (sECG) in diagnosing coronary artery disease (CAD).

METHOD

A decision tree was constructed to compare four strategies for investigation of suspected CAD previously assessed in the formulation of clinical guidelines for the United Kingdom (UK) to two new strategies incorporating CCS. Sensitivity (96%; 95% CI 95.4-96.4%) and specificity (40%; 95% CI 38.7-41.4%) values for CCS were derived from a meta-analysis of 10,760 patients. Other input variables were obtained from a previous EA and average prices for hospital procedures in the UK. A threshold of £30,000/Quality-adjusted Life Year (QALY) was considered cost-effective.

RESULTS

Using net monetary benefit calculations, CCS-based strategies were found to be cost-effective compared to sECG equivalents at all assessed prevalence of CAD. Using CCS prior to myocardial perfusion scintigraphy (MPS) and catheter angiography (CA) was found to be cost-effective at pre-test probabilities (PTP) below 30%.

CONCLUSIONS

Adoption of CCS as an alternative to sECG in investigating suspected stable angina in low PTP population (<30%) would be cost-effective. In patients with PTP of CAD >30%, proceeding to MPS or CA would be more cost-effective than performing either CCS or sECG.

KEY POINTS

Coronary calcium scoring (CCS) is useful for assessing coronary artery atherosclerosis It can be performed with multi-detector CT, which is now widely available It plays a role in excluding disease in suspected stable angina Our study assesses its role in this setting as alternative to stress-ECG Adoption of CCS as an alternative to sECG could prove cost-effective.

A review of patient dose and optimisation methods in adult and paediatric CT scanning

An increasing number of publications and international reports on computed tomography (CT) have addressed important issues on optimised imaging practice and patient dose. This is partially due to recent technological developments as well as to the striking rise in the number of CT scans being requested. CT imaging has extended its role to newer applications, such as cardiac CT, CT colonography, angiography and urology. The proportion of paediatric patients undergoing CT scans has also increased. The published scientific literature was reviewed to collect information regarding effective dose levels during the most common CT examinations in adults and paediatrics. Large dose variations were observed (up to 32-fold) with some individual sites exceeding the recommended dose reference levels, indicating a large potential to reduce dose. Current estimates on radiation-related cancer risks are alarming. CT doses account for about 70% of collective dose in the UK and are amongst the highest in diagnostic radiology, however the majority of physicians underestimate the risk, demonstrating a decreased level of awareness. Exposure parameters are not always adjusted appropriately to the clinical question or to patient size, especially for children. Dose reduction techniques, such as tube-current modulation, low-tube voltage protocols, prospective echocardiography-triggered coronary angiography and iterative reconstruction algorithms can substantially decrease doses. An overview of optimisation studies is provided. The justification principle is discussed along with tools that assist clinicians in the decision-making process. There is the potential to eliminate clinically non-indicated CT scans by replacing them with alternative examinations especially for children or patients receiving multiple CT scans.

Radiation dose reduction with increasing utilization of prospective gating in 64-multidetector cardiac computed tomography angiography

BACKGROUND

Medical radiation exposure is a major concern, and several methods have been proposed to reduce radiation doses in multidetector cardiac computed tomography (CT).

OBJECTIVE

The purpose of this study was to review radiation doses of clinical cardiac CT performed at our center and to evaluate the effect of radiation dose reduction strategies on the median dose delivered to patients over time.

METHODS

This study included 623 consecutive clinical patients (male, 58%) who were referred for imaging. The effective dose (mSv) was derived from the product of the dose-length-product (DLP) and a conversion coefficient for the chest (0.014).

RESULTS

The median radiation dose of all patients was 3.0 mSv (interquartile range [IQR], 1.9-8.1 mSv). A significant difference was observed in radiation dose between the prospective (n = 384) and retrospective (n = 239) gating groups (2.0 vs 9.6 mSv; P < 0.0001). Compared with patients with coronary artery bypass grafting (CABG; n = 52), patients without CABG had significantly lower median radiation dose (prospective gating: 2.0 vs 3.4 mSv, P < 0.0001; retrospective gating: 9.3 vs 10.3 mSv, P < 0.0001). In patients with CABG, a significant difference was observed in radiation dose between prospective and retrospective gating (3.4 vs 10.3; P < 0.0001). The median radiation doses per month at our center decreased from 6.2 to 2.1 mSv over time with increasing use of prospective gating (≤91%).

CONCLUSION

Radiation reduction techniques have led to progressive decreases in radiation exposure over time, primarily because of prospective gating.

Coronary artery calcium and plaque association with left ventricular mass, assessed by multi-row detector computed tomography

INTRODUCTION

Few studies have been published describing the association of coronary plaques and coronary artery calcium (CAC) to left ventricular (LV) mass and LV function using multi-detector computed tomography (MDCT). Coronary plaques can potentially influence the LV function. We sought to evaluate LV mass and function on MDCT and its correlation with CAC and plaque burden in the coronary arteries.

METHODS

We included 197 symptomatic patients from the multicenter ACCURACY Study. The LV mass was measured manually using Advantage 4.4 workstation. Interobserver variability of LV mass was assessed using 34 randomly selected studies. LV mass was indexed to the body surface area. The coronary plaque severity was assessed in each segment using MDCT, following the 15 segment American Heart Association model. Plaque and segment scores were calculated accordingly. Statistical analysis using multiple logistic regression analysis was performed.

RESULTS

We divided the cohort into those with CAC=0 [n=67 (34%)] and those with CAC greater than 0 [n=130 (66%)]. A significant correlation was found between indexed LV mass and CAC, plaque, and segment scores in both adjusted and unadjusted models. A significant association was observed between nonindexed LV mass with CAC, MDCT plaque score and segment score upon adjusting for various cardiovascular risk factors. A significant correlation was found between hyperlipidemia, hypertension, family history of CAD, and greater than 50% and greater than 70% stenosis on invasive cardiac catheterization with LV mass (all P<0.05).

CONCLUSION

To our knowledge, this is the first study evaluating coronary plaque on computed tomographic angiography with LV mass. We were able to show a significant correlation of LV mass with CAC score, and with total plaque and total segment scores. The poor prognosis associated with increased CAC scores may be partially explained by this association with increased LV mass.

[Dose reduction during CT coronary angiography]

Dose delivery during CT coronary angiography with retrospective ECG gating is high especially due to the important slice overlapping. Optimization of the acquisition parameters is necessary to reduce patient exposure. First, the height of the scan field should be limited to the heart. Both kV and mA should be adjusted based on patient morphology. ECG gated exposure modulation with mA reduction during systole, a technique most applicable for patients with slow and regular heart rate, can result in a dose reduction up to 50%. The use of prospective ECG gating can also reduce patient dose. This technique also requires patients with slow and regular heart rate.

Radiation dose of cardiac computed tomography - what has been achieved and what needs to be done

This review highlights the recently introduced techniques by manufacturers and various research workers to reduce radiation dose in coronary CT. It discusses in detail the development of ECG-based tube current modulation, the application of low tube voltage protocols and prospective ECG-gating. It also briefly discusses two further methods of dose reduction, namely minimisation of the x-y anatomical coverage and adaptive statistical iterative reconstruction.

Measurement of thoracic bone mineral density with quantitative CT

PURPOSE

To create standard thoracic bone mineral density (BMD) values for patients undergoing cardiac computed tomography (CT) by using thoracic quantitative CT and to compare these BMDs (in a subpopulation) with those obtained by using lumbar spine quantitative CT.

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant study. A total of 9585 asymptomatic subjects (mean age, 56 years; age range, 30-90 years) who underwent coronary artery calcium scanning, including 4131 women, were examined. Patients with vertebral deformities or fractures were excluded. Six hundred forty-four subjects (322 of whom were female) also underwent lumbar quantitative CT. The mean thoracic vertebral BMDs for both sexes were reported separately in a subgroup of subjects aged 30 years and in 29 age-based subgroups in 2-year intervals from ages 30 to 90 years. The formulas used to calculate the female T score (T(f)) and the male T score (T(m)) on the basis of thoracic quantitative CT measurements were as follows: T(f) = (BMD(im) - 222)/36, and T(m) = (BMD(im) - 215)/33, where BMD(im) is the individual mean BMD. Comparisons between thoracic quantitative CT and lumbar quantitative CT measurements, as well as analyses of intraobserver, interobserver, and interscan variability, were performed.

RESULTS

The young-subgroup mean BMD was 221.9 mg/mL ± 36.2 (standard deviation) for the female subjects and 215.2 mg/mL ± 33.2 for the male subjects. The mean thoracic BMDs for the female and male subjects were found to be 20.7% higher and 17.0% higher, respectively, than the values measured with lumbar quantitative CT (P < .001 for both comparisons). A significant positive association between the thoracic and lumbar quantitative CT measurements (r > 0.85, P < .001) was found. Intraobserver, interobserver, and interscan variabilities in thoracic quantitative CT measurements were 2.5%, 2.6%, and 2.8%, respectively.

CONCLUSION

There was a significant association between the mean thoracic and lumbar BMDs. Therefore, standard derived measurements (young-subgroup BMD ± standard deviation) based on these data can be used with thoracic CT images to estimate the bone mineral status.

Detection of aortic regurgitation with 64-slice multidetector computed tomography (MDCT)

RATIONALE AND OBJECTIVES

To determine the diagnostic accuracy of 64-row multidetector cardiac computed tomography (MDCT) in detecting aortic regurgitation (AR) on prospectively acquired images with trans-thoracic echocardiography (TTE) as a reference standard.

MATERIALS AND METHODS

Forty-three consecutive patients underwent MDCT and TTE. AR was defined on MDCT images acquired at 75% phase of R-R interval as the lack of aortic cusps coaptation. The maximum regurgitant orifice area (ROA) was planimetered and compared to TTE.

RESULTS

All 29 patients with AR on TTE were correctly identified by MDCT. The sensitivity, specificity, positive predictive value, and negative predictive value of MDCT were 100%, 85.7%, 93.5%, and 100%, respectively. Sixteen, nine, and four patients were found to have mild, moderate, and severe AR on TTE, respectively. The corresponding ROA by MDCT were 3.25 +/- 1.04 mm(2), 4.16 +/- 1.19 mm(2), and 11.30 +/- 6.13 mm(2), respectively.

CONCLUSION

MDCT data acquired for the coronary artery evaluation can be used for the detection of aortic regurgitation with high diagnostic accuracy without additional scanning or radiation and can support appropriate referral for TTE.

Potential clinical and economic consequences of noncardiac incidental findings on cardiac computed tomography

OBJECTIVES

We sought to determine the incidence, clinical significance, and potential financial impact of noncardiac incidental findings (IF) identified with cardiac computed tomography (CT).

BACKGROUND

Cardiac CT is gaining acceptance and may lead to the frequent discovery of extracardiac IF.

METHODS

Consecutive patients undergoing cardiac CT had noncardiac structures evaluated after full field of view (32 to 50 cm) reconstruction. IF were categorized as clinically significant (CS), indeterminate, or clinically insignificant. Patient follow-up was performed by telephone, and verified with hospital records and/or communication with physicians.

RESULTS

Of 966 patients (58 +/- 16 years of age, 55.4% men, >98% outpatients), 401 (41.5%) patients had noncardiac IF. A total of 12 (1.2%) patients had CS findings, and 68 (7.0%) patients had indeterminate findings. At follow-up (18.4 +/- 7.6 months), none of the indeterminate findings became CS. Although 3 patients with indeterminate findings were diagnosed with malignant lesions, they were unrelated to the IF. After adjusting for age, IF were not an independent predictor of noncardiac death. Noncardiac death and cancer death in patients with and without IF were not statistically different. One patient suffered a major complication related to the investigation of an IF. The total direct cost associated with investigating IF was Canadian $57,596 (U.S. $83,035).

CONCLUSIONS

Although noncardiac IF are common, clinically significant or indeterminate IF are less prevalent. Rates of death were similar in patients with and without IF, and IF was not an independent predictor of noncardiac death. The investigation of IF is not without cost or risk. Larger studies are required to assess the potential mortality benefit of identifying IF.