Radiation dose of cardiac CT—what is the evidence?

Current evidence and most pertinent literature on the radiation dose of cardiac computed tomography (CT) for the noninvasive assessment of coronary artery disease are reviewed. The various means for adjusting CT protocols to lower the radiation to a level that is as low as reasonably achievable are discussed. It is shown that for the target population of cardiac CT, the direct visualization of the heart and coronary arteries outweighs the hypothetical risk of the investigation, provided that indications are prudent and the protocols appropriat

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 reconstructio

The impact of cardiac CT on the appropriate utilization of catheter coronary angiography

The purpose of this study was to evaluate the impact of computed tomography coronary angiography (CTCA) on the appropriate utilization of catheter angiography (CA). This observational trial analyzed all patients undergoing CA in 2006 and 2007 in one hospital. In 2007, patients having a low to intermediate cardiovascular risk and suspicion of coronary artery disease (CAD) and those with suspicion of progression of known organic heart disease (OHD) underwent CTCA either prior to CA or as the sole imaging modality. Appropriate utilization of CA was defined as: (1) percentage of patients showing normal or non-significant findings at CA, (2) percentage of self-referred patients to CA, and (3) percentage of patients with known OHD undergoing CA without immediate operative or interventional consequences. Use of CTCA resulted in a significant drop in the percentage of CA examinations in patients with suspected CAD showing normal or non-significant findings (19% in 2006, 10% in 2007, P<0.001). The percentage of self-referred CA significantly dropped (29% in 2006, 10% in 2007, P<0.001). CT ruled-out CAD in 74/151 (49%) patients, obviating subsequent CA. During a follow-up of 15±4months, CA and percutaneous interventions was considered necessary in 2/74 patients. CT ruled-out progression of known OHD in 53/60 (90%) patients, while one patient underwent CA and percutaneous intervention during a follow-up period of 16±4months. No reduction of CA examinations without immediate consequences was found in patients with known OHD (13% in 2006, 27% in 2007). In patients with suspicion of CAD, CTCA improved the appropriate utilization of CA without jeopardizing patient safety, along with a decrease of self-referred patients for CA. CTCA did not influence the appropriate utilization of CA in patients with known OH

Multislice CT in the pre- and postinterventional evaluation of mesenteric perfusion

Multislice computed tomography angiography (CTA) has been found feasible for the evaluation of visceral vasculature. The development of multislice technology has overcome past limitations. First, the faster scanning speed increases volume coverage during a single breath-hold and improves the exploitation of contrast medium. Second, the better spatial resolution results in nearly isotropic voxels allowing reconstruction of high-resolution three-dimensional images with different algorithms. Volume rendering is capable of displaying the visceral vasculature from any external vantage point. Compared to conventional angiography, CTA not only delineates vessels but also depicts the anatomical relationship to adjacent structures and allows the evaluation of perfused organs. CTA also has become an emerging tool for the pre- and postinterventional assessment of vascular anatomy. The purpose of this pictorial essay is to present a spectrum of visceral vascular diseases and interventional and surgical therapies, and to highlight the role of postprocessing for their evaluatio

Multi-detector computed tomography of acute abdomen

Acute abdominal pain is one of the most common causes for referrals to the emergency department. The sudden onset of severe abdominal pain characterising the "acute abdomen” requires rapid and accurate identification of a potentially life-threatening abdominal pathology to provide a timely referral to the appropriate physician. While the physical examination and laboratory investigations are often non-specific, computed tomography (CT) has evolved as the first-line imaging modality in patients with an acute abdomen. Because the new multi-detector CT (MDCT) scanner generations provide increased speed, greater volume coverage and thinner slices, the acceptance of CT for abdominal imaging has increased rapidly. The goal of this article is to discuss the role of MDCT in the diagnostic work-up of acute abdominal pai

Spontaneous Dissection of a Septal Coronary Artery Mimicking Myocarditis

Acute chest pain and dyspnea often raise coronary disease suspicion. When echocardiography and cardiac computed tomography findings appear normal, alternative diagnoses should be explored. We present a case initially suggestive of myocarditis but later revealed as coronary dissection by cardiac magnetic resonance. This case emphasizes the role of advanced imaging in atypical cardiac presentations

Diagnostic Performance of the Darth Vader Sign for the Diagnosis of Lumbar Spondylolysis in Routinely Acquired Abdominal CT

Spondylolysis is underdiagnosed and often missed in non-musculoskeletal abdominal CT imaging. Our aim was to assess the inter-reader agreement and diagnostic performance of a novel "Darth Vader sign" for the detection of spondylolysis in routine axial images. We performed a retrospective search in the institutional report archives through keyword strings for lumbar spondylolysis and spondylolisthesis. Abdominal CTs from 53 spondylolysis cases (41% female) and from controls (n = 6) without spine abnormalities were identified. A total of 139 single axial slices covering the lumbar spine (86 normal images, 40 with spondylolysis, 13 with degenerative spondylolisthesis without spondylolysis) were exported. Two radiology residents rated all images for the presence or absence of the "Darth Vader sign". The diagnostic accuracy for both readers, as well as the inter-reader agreement, was calculated. The "Darth Vader sign" showed an inter-reader agreement of 0.77. Using the "Darth Vader sign", spondylolysis was detected with a sensitivity and specificity of 65.0-88.2% and 96.2-99.0%, respectively. The "Darth Vader sign" shows excellent diagnostic performance at a substantial inter-reader agreement for the detection of spondylolysis. Using the "Darth Vader sign" in the CT reading routine may be an easy yet effective tool to improve the detection rate of spondylolysis in non-musculoskeletal cases and hence improve patient care

Stabilized reduced-order models for unsteady incompressible flows in three-dimensional parametrized domains

In this work we derive a parametric reduced-order model (ROM) for the unsteady three-dimensional incompressible Navier–Stokes equations without additional pre-processing on the reduced-order subspaces. Concerning the high-fidelity, full-order model, we start from a streamline-upwind Petrov–Galerkin stabilized finite element discretization of the equations using elements for velocity and pressure, respectively. We rely on Galerkin projection of the discretized equations onto reduced basis subspaces for the velocity and the pressure, respectively, obtained through Proper Orthogonal Decomposition on a dataset of snapshots of the full-order model. Both nonlinear and nonaffinely parametrized algebraic operators of the reduced-order system of nonlinear equations, including the projection of the stabilization terms, are efficiently assembled exploiting the Discrete Empirical Interpolation Method (DEIM), and its matrix version (MDEIM), thus obtaining an efficient offline–online computational splitting. We apply the proposed method to (i) a two-dimensional lid-driven cavity flow problem, considering the Reynolds number as parameter, and (ii) a three-dimensional pulsatile flow in stenotic vessels characterized by geometric and physiological parameter variations. We numerically show that the projection of the stabilization terms on the reduced basis subspace and their reconstruction using (M)DEIM allows to obtain a stable ROM with coupled velocity and pressure solutions, without any need for enriching the reduced velocity space, or further stabilizing the ROM. Additionally, we demonstrate that our implementation allows to compute the ROM solution about 20 times faster than the full order model