Correction to: Applicability and accuracy of pretest probability calculations implemented in the NICE clinical guideline for decision making about imaging in patients with chest pain of recent onset.

The original version of this article, published on 19 March 2018, unfortunately contained a mistake. The following correction has therefore been made in the original: The names of the authors Philipp A. Kaufmann, Ronny Ralf Buechel and Bernhard A. Herzog were presented incorrectly.

Applicability and accuracy of pretest probability calculations implemented in the NICE clinical guideline for decision making about imaging in patients with chest pain of recent onset.

OBJECTIVES: To analyse the implementation, applicability and accuracy of the pretest probability calculation provided by NICE clinical guideline 95 for decision making about imaging in patients with chest pain of recent onset. METHODS: The definitions for pretest probability calculation in the original Duke clinical score and the NICE guideline were compared. We also calculated the agreement and disagreement in pretest probability and the resulting imaging and management groups based on individual patient data from the Collaborative Meta-Analysis of Cardiac CT (CoMe-CCT). RESULTS: 4,673 individual patient data from the CoMe-CCT Consortium were analysed. Major differences in definitions in the Duke clinical score and NICE guideline were found for the predictors age and number of risk factors. Pretest probability calculation using guideline criteria was only possible for 30.8 % (1,439/4,673) of patients despite availability of all required data due to ambiguity in guideline definitions for risk factors and age groups. Agreement regarding patient management groups was found in only 70 % (366/523) of patients in whom pretest probability calculation was possible according to both models. CONCLUSIONS: Our results suggest that pretest probability calculation for clinical decision making about cardiac imaging as implemented in the NICE clinical guideline for patients has relevant limitations. KEY POINTS: • Duke clinical score is not implemented correctly in NICE guideline 95. • Pretest probability assessment in NICE guideline 95 is impossible for most patients. • Improved clinical decision making requires accurate pretest probability calculation. • These refinements are essential for appropriate use of cardiac CT.

Fat suppression in magnetic resonance imaging of the head and neck region: is the two-point DIXON technique superior to spectral fat suppression?

OBJECTIVE: The aim of our study was to systematically compare two-point Dixon fat suppression (FS) and spectral FS techniques in contrast enhanced imaging of the head and neck region. METHODS: Three independent readers analysed coronal T1 weighted images recorded after contrast medium injection with Dixon and spectral FS techniques with regard to FS homogeneity, motion artefacts, lesion contrast, image sharpness and overall image quality. RESULTS: 85 patients were prospectively enrolled in the study. Images generated with Dixon-FS technique were of higher overall image quality and had a more homogenous FS over the whole field of view compared with the standard spectral fat-suppressed images (p < 0.001). Concerning motion artefacts, flow artefacts, lesion contrast and image sharpness no statistically significant difference was observed. CONCLUSION: The Dixon-FS technique is superior to the spectral technique due to improved homogeneity of FS and overall image quality while maintaining lesion contrast. Advances in knowledge: T1 with Dixon FS technique offers, compared to spectral FS, significantly improved FS homogeneity and over all image quality in imaging of the head and neck region.

Long-Range Real Migration of Implantable Cardioverter Defibrillator Lead.

The need for pacemaker and implantable cardioverter defibrillator (ICD) lead revisions and extractions is steadily increasing. Despite the lack of representative studies, the risk of lead extraction is frequently considered to be lower than leaving nonfunctional leads in situ. We report the case of a patient who was referred to our institution for exchange of a malfunctioning ICD lead. The diagnostic work-up revealed a long-segment transmural migration of the ICD lead at the site of the subclavian and innominate vein. Due to the unpredictable risk of vein perforation, we abandoned the extraction procedure.

In vivo analysis of the vascular pattern of the superficial temporal artery based on digital subtraction angiography.

BACKGROUND: Existing anatomic descriptions of the superficial temporal artery (STA) are mainly based on cadaver studies and do not accurately reflect the in vivo situation. In this study, the anatomical course and branching pattern of the STA were analyzed with digital subtraction angiographies (DSAs). METHODS: DSAs of 93 Caucasian individuals between 16- and 79-years old were retrospectively analyzed regarding the course and branching pattern of the STA as well as surgically relevant inner diameters and lengths of its main branches. RESULTS: In total, 11 variations in the branching pattern of the terminal STA were found. About 89% of the examined individuals demonstrated the classic variation in which the main trunk of the STA bifurcates into a single frontal and parietal branch. In 60% of cases with an existing bifurcation, the division of the main trunk of the STA was located above the zygoma. The mean inner diameters of the STA main trunk, the frontal branch and the parietal branch were 2.4 ± 0.6 mm, 1.3 ± 0.6 mm and 1.2 ± 0.4 mm, respectively. The surgically relevant "working lengths" of the frontal and parietal branches above the upper margin of the zygoma up to an inner diameter of 1 mm were 106.4 ± 62.1mm and 99.7 ± 40.9 mm, respectively. CONCLUSIONS: The common variations of the branching pattern of the STA are described in this study. Furthermore, surgically relevant inner diameters and lengths of the main branches of the STA are determined. These findings should improve our understanding of the suitability and usefulness of the STA for various surgical procedures.

Added value of integrated circuit detector in head CT: objective and subjective image quality in comparison to conventional detector design.

RATIONALE AND OBJECTIVES: A new computed tomography (CT) detector with integrated electric components and shorter conducting pathways has recently been introduced to decrease system inherent electronic noise. The purpose of this study was to assess the potential benefit of such integrated circuit detector (ICD) in head CT by comparing objective and subjective image quality in low-dose examinations with a conventional detector design. MATERIALS AND METHODS: Using a conventional detector, reduced-dose noncontrast head CT (255 mAs; effective dose, 1.7 mSv) was performed in 25 consecutive patients. Following transition to ICD, 25 consecutive patients were scanned using identical imaging parameters. Images in both groups were reconstructed with iterative reconstruction (IR) and filtered back projection (FBP) and assessed in terms of quantitative and qualitative image quality. RESULTS: Acquisition of head CT using ICD increased signal-to-noise ratio of gray and white matter by 14% (10.0 ± 1.6 vs. 11.4 ± 2.5; P = .02) and 17% (8.2 ± 0.8 vs. 9.6 ± 1.5; P = .000). The associated improvement in contrast-to-noise ratio was 12% (2.0 ± 0.5 vs. 2.2 ± 0.6; P = .121). In addition, there was a 51% increase in objective image sharpness (582 ± 85 vs. 884.5 ± 191; change in HU/Pixel; P < .000). Compared to standard acquisitions, subjective grading of noise and overall image quality scores were significantly improved with ICD (2.1 ± 0.3 vs. 1.6 ± 0.3; P < .000; 2.0 ± 0.5 vs. 1.6 ± 0.3; P = .001). Moreover, streak artifacts in the posterior fossa were substantially reduced (2.3 ± 0.7 vs. 1.7 ± 0.5; P = .004). CONCLUSIONS: At the same radiation level, acquisition of head CT with ICD achieves superior objective and subjective image quality and provides potential for significant dose reduction.

Radiation dose reduction in soft tissue neck CT using adaptive statistical iterative reconstruction (ASIR).

PURPOSE: To compare objective and subjective image quality in neck CT images acquired at different tube current-time products (275 mAs and 340 mAs) and reconstructed with filtered-back-projection (FBP) and adaptive statistical iterative reconstruction (ASIR). MATERIALS AND METHODS: HIPAA-compliant study with IRB approval and waiver of informed consent. 66 consecutive patients were randomly assigned to undergo contrast-enhanced neck CT at a standard tube-current-time-product (340 mAs; n = 33) or reduced tube-current-time-product (275 mAs, n = 33). Data sets were reconstructed with FBP and 2 levels (30%, 40%) of ASIR-FBP blending at 340 mAs and 275 mAs. Two neuroradiologists assessed subjective image quality in a blinded and randomized manner. Volume CT dose index (CTDIvol), dose-length-product (DLP), effective dose, and objective image noise were recorded. Signal-to-noise ratio (SNR) was computed as mean attenuation in a region of interest in the sternocleidomastoid muscle divided by image noise. RESULTS: Compared with FBP, ASIR resulted in a reduction of image noise at both 340 mAs and 275 mAs. Reduction of tube current from 340 mAs to 275 mAs resulted in an increase in mean objective image noise (p=0.02) and a decrease in SNR (p = 0.03) when images were reconstructed with FBP. However, when the 275 mAs images were reconstructed using ASIR, the mean objective image noise and SNR were similar to those of the standard 340 mAs CT images reconstructed with FBP (p>0.05). Subjective image noise was ranked by both raters as either average or less-than-average irrespective of the tube current and iterative reconstruction technique. CONCLUSION: Adapting ASIR into neck CT protocols reduced effective dose by 17% without compromising image quality.

Association between linear measurements of corpus callosum and gait in the elderly.

PURPOSE: Segmentation and diffusion-tensor-imaging of the corpus callosum (CC) have been linked to gait impairment. However, such measurements are impracticable in clinical routine. The purpose of this study was to evaluate the association between simple linear measurements of CC thickness with gait. METHODS: Two hundred and seventy-two community-dwelling subjects underwent neurological assessment and brain MRI. Mid-sagittal reformats of T1-weighted images were used to determine CC thickness. The association of measurements with clinical evaluation of gait was assessed by multivariate regression, controlling for numerous clinical and imaging confounders. Differences in CC thickness were, moreover, compared between subgroups with no, moderate or severe impairment of gait. RESULTS: In univariate analyses, thickness of the genu and body of CC but not the splenium were associated with postural stability (P < 0.01). Multivariate regression revealed thickness of CC genu as the only imaging variable independently associated with gait (P = 0.01). Genu thickness was significantly different between subjects with high and low (P = 0.0003) or high and moderate (P = 0.001) risk of fall. CONCLUSION: Atrophy of the CC genu is an imaging marker of gait impairment in the elderly suggesting higher risk of fall. Simple linear measurements of CC can help in MRI evaluation of patients with gait impairment. KEY POINTS: • Regional atrophy of the corpus callosum reflects disruption of gait regulation • Genu thickness on cranial MRI is an independent marker of gait impairment • Findings help in the MRI evaluation of patients with gait impairment.

Individual patient data meta-analysis for the clinical assessment of coronary computed tomography angiography: protocol of the Collaborative Meta-Analysis of Cardiac CT (CoMe-CCT).

BACKGROUND: Coronary computed tomography angiography has become the foremost noninvasive imaging modality of the coronary arteries and is used as an alternative to the reference standard, conventional coronary angiography, for direct visualization and detection of coronary artery stenoses in patients with suspected coronary artery disease. Nevertheless, there is considerable debate regarding the optimal target population to maximize clinical performance and patient benefit. The most obvious indication for noninvasive coronary computed tomography angiography in patients with suspected coronary artery disease would be to reliably exclude significant stenosis and, thus, avoid unnecessary invasive conventional coronary angiography. To do this, a test should have, at clinically appropriate pretest likelihoods, minimal false-negative outcomes resulting in a high negative predictive value. However, little is known about the influence of patient characteristics on the clinical predictive values of coronary computed tomography angiography. Previous regular systematic reviews and meta-analyses had to rely on limited summary patient cohort data offered by primary studies. Performing an individual patient data meta-analysis will enable a much more detailed and powerful analysis and thus increase representativeness and generalizability of the results. The individual patient data meta-analysis is registered with the PROSPERO database (CoMe-CCT, CRD42012002780). METHODS/DESIGN: The analysis will include individual patient data from published and unpublished prospective diagnostic accuracy studies comparing coronary computed tomography angiography with conventional coronary angiography. These studies will be identified performing a systematic search in several electronic databases. Corresponding authors will be contacted and asked to provide obligatory and additional data. Risk factors, previous test results and symptoms of individual patients will be used to estimate the pretest likelihood of coronary artery disease. A bivariate random-effects model will be used to calculate pooled mean negative and positive predictive values as well as sensitivity and specificity. The primary outcome of interest will be positive and negative predictive values of coronary computed tomography angiography for the presence of coronary artery disease as a function of pretest likelihood of coronary artery disease, analyzed by meta-regression. As a secondary endpoint, factors that may influence the diagnostic performance and clinical value of computed tomography, such as heart rate and body mass index of patients, number of detector rows, and administration of beta blockade and nitroglycerin, will be investigated by integrating them as further covariates into the bivariate random-effects model. DISCUSSION: This collaborative individual patient data meta-analysis should provide answers to the pivotal question of which patients benefit most from noninvasive coronary computed tomography angiography and thus help to adequately select the right patients for this test.

Diffuse alveolar hemorrhage in patients with hematological malignancies: HRCT patterns of pulmonary involvement and disease course.

OBJECTIVE: To analyze high-resolution computed tomography (HRCT) patterns of lung involvement and disease course in patients with hematological malignancies experiencing diffuse alveolar hemorrhage (DAH) after chemotherapy ± allogeneic stem cell transplantation (allo-SCT). MATERIALS AND METHODS: Sixteen patients experiencing DAH after chemotherapy ± allo-SCT were enrolled. A total of 74 computed tomography (CT) scans obtained before, during, and after onset of DAH were evaluated retrospectively. RESULTS: CT features of DAH are each, by oneself, nonspecific. However, conjoint bilateral, diffuse, and dependent ground glass opacity ± crazy paving, accompanied by airspace bronchograms, should suggest this complication. The HRCT course comprises a wide range of trends that are not predictive for patient's outcome, but progression of parenchymal consolidations at follow up was more often detrimental.

Therapy-related noninfectious complications in patients with hematologic malignancies: high-resolution computed tomography findings.

Pulmonary complications are a leading source of mortality in patients treated for hematologic malignancies. After hematopoietic stem cell transplantation, treatment-related noninfectious complications constitute more than half of the pulmonary pathology and represent a particular diagnostic challenge. This review illustrates the high-resolution computed tomography findings of common therapy-related complications and thereby demonstrates a high degree of overlap between the patterns of various toxicities. Clinical background knowledge of the distinct entities is reviewed and highlighted as an indispensable instrument to narrow the differential diagnosis.

Imaging findings in tick-borne encephalitis with differential diagnostic considerations.

OBJECTIVE: The purpose of this article is to provide a practical review of the spectrum of imaging findings in patients with tick-borne encephalitis (TBE) and to address possible differential diagnoses. CONCLUSION: Imaging findings in TBE resemble those of other infections, such as meningoencephalitis. However, a predilection for the thalami, basal ganglia, cerebellum, and anterior horns of the spinal cord suggests the possibility of TBE.

Accuracy of automated attenuation-based 3-dimensional segmentation: in the analysis of left ventricular function compared with magnetic resonance imaging.

We evaluated attenuation-based 3-dimensional segmentation for the analysis of left ventricular function, using as our standard of reference magnetic resonance imaging and dual-source computed tomography with traditional short-axis planimetry.Twenty patients with known or suspected coronary artery disease were examined prospectively. In all magnetic resonance and computed tomographic datasets, global functional values were determined by 2-dimensional planimetry. Computed tomographic scans were further evaluated by automated 3-dimensional segmentation, and the results were compared by Pearson correlation and Bland-Altman analysis.Agreement between magnetic resonance imaging and dual-source computed tomographic 2-dimensional planimetry was good for all values (end-diastolic volume, bias= -4.2, r=0.99; end-systolic volume, bias= -1.7, r=0.99, stroke-volume, bias= -2.4, r=0.98; ejection fraction, bias=0.26, r=0.94; and myocardial mass, bias= 2.5, r=0.90). By contrast, dual-source computed tomographic 3-dimensional segmentation overestimated end-diastolic volume (bias= -19.1, P <0.001), stroke-volume (bias= -16.9, P <0.001), and myocardial mass (bias= -34.4, P <0.001). Moreover, correlation with magnetic resonance imaging proved disappointing for ejection fraction (r=0.72). Results were similar in a direct comparison between dual-source computed tomographic 2-dimensional planimetry and 3-dimensional segmentation (end-diastolic volume, bias= -14.9, r=0.94; end-systolic volume, bias= -0.5, r=0.90; stroke volume, bias= -14.5, r=0.83; ejection fraction, bias= -2.8, r=0.74; and myocardial mass, bias= -36.8, r=0.79).Due to significant overestimation of volumes and poor correlation of ejection fraction with cine magnetic resonance imaging results, attenuation-based 3-dimensional segmentation compares unfavorably with traditional planimetry. Hence this method should be used with caution, and its time benefits should be weighed against its imprecision of functional analysis.

Volume perfusion-CT of the liver: insights and applications.

The purpose of this article is to provide an up-to-date view on the spectrum of applications of volume perfusion-CT in the liver. Volume perfusion-CT yields important information on liver architecture and function by enabling quantification of dual liver parenchymal blood supply. Additional characterization of diffuse and focal liver diseases by illustration of distinct flow dynamics and permeability may become an important adjunct in the CT-evaluation of liver pathologies.

Can whole-body low-dose multidetector CT exclude the presence of myeloma bone disease in patients with monoclonal gammopathy of undetermined significance (MGUS)?

RATIONALE AND OBJECTIVES: To determine the benefit of using whole-body low-dose computed tomography (WBLD-CT) in patients with monoclonal gammopathy of undetermined significance (MGUS) for exclusion of multiple myeloma (MM) bone disease. MATERIALS AND METHODS: Seventy-one consecutive patients with confirmed MGUS (as defined by the latest criteria of the International Myeloma Working Group) who underwent WBLD-CT for diagnosis were identified retrospectively by a search of our institution's electronic medical record database (2002-2009). Patients were classified as low-risk or intermediate/high-risk and followed over a ≥2-year period with additional CT imaging and/or laboratory parameters. Presence of osteolysis, medullary, or extramedullary abnormalities compatible with involvement by MM was recorded. A diffuse or focal increase in medullary density to Hounsfield unit (HU) values >20 HU/>0 HU was considered suspicious for bone marrow infiltration if no other causes identifiable. RESULTS: The presence of osteolysis was excluded in all 71 patients with MGUS at initial diagnosis and patients were surveilled for ≥2 years. Lytic changes were observed at follow-up in 1/71 patients that progressed to MM and were detectable via WBLD-CT at an early stage (even before a significant rise in M-protein was recorded). In 3/71 patients with MGUS (4%) suspicious bone marrow attenuation values were measured, disclosing disease progression to smoldering myeloma in another patient and false-positive results in 2/71 patients. Bone marrow attenuation assessment resulted in a specificity and negative predictive value of 97%, respectively. No significant difference with respect to bone marrow attenuation was observed in patients with low-risk MGUS versus intermediate- to high-risk MGUS. One of 71 patients showed serologic disease progression to active MM without bone abnormalities detectable. CONCLUSION: WBLD-CT reliably excludes findings compatible with myeloma in MGUS and thereby complements hematologic laboratory analysis.

Volume and attenuation computed tomography measurements for interim evaluation of Hodgkin and follicular lymphoma as an additional surrogate parameter for more confident response monitoring: a pilot study.

PURPOSE: To retrospectively determine the potential role of additional computed tomography (CT) attenuation measurements for interim response evaluation in residual masses of patients with Hodgkin disease (HD) and follicular non-Hodgkin lymphoma (NHL). MATERIALS AND METHODS: In this retrospective study, 39 patients with HD and 35 patients with NHL presented with residual masses at mid-treatment CT (after 2-4 cycles of chemotherapy) and were assessed via contrast-enhanced CT at baseline, mid-treatment and post-treatment. Volume was recorded as whole-tumour volume. A tumour attenuation ratio (TAR) was calculated as the quotient of attenuation between tumour and muscle at the respective point in time versus baseline. The standard deviation of attenuation values within the tumour volume was recorded to estimate tumour heterogeneity. Results were correlated with relapse-free survival determined at a minimum of 12 months after end-treatment CT. RESULTS: Tumour volume and TAR at interim versus baseline control were significantly reduced in responders compared with non-responders, even after controlling for age, stage, treatment regimen, and baseline tumour volume. No significant differences with respect to the standard deviation of attenuation values within the tumour volumes (tumour heterogeneity) were observed. The volume and attenuation CT (VACT) criteria yielded the highest sensitivities and specificities for the identification of non-response at a threshold of a >20% increase in volume and an increase in TAR at interim control, i.e. 88% (NHL 80%, HD 100%) and 98% (NHL 97%, HD 100%), respectively. The negative predictive values reached by VACT analysis were >=97%, according to both parameters. CONCLUSION: Mid-treatment response assessment of residual masses in patients with HD and NHL using VACT may aid in the risk stratification as an additional surrogate parameter.

Plaque distribution in clopidogrel responders and low responders as determined by multislice computed tomography.

Via multidetector computed tomography (MDCT) with retrospective electrographic gating, we sought to evaluate whether plaque distribution differs between responders and low responders to clopidogrel treatment. Low response was defined as a post-treatment aggregation of 35% to 70%. In this observational study, we enrolled 62 patients (mean age, 64.8 ± 8.9 yr; 51 men). In addition to determining coronary calcium scores, we performed noninvasive coronary angiography with MDCT before stent implantation. Plaques were visually classified as calcified, mixed, or completely noncalcified. Mean density was measured. Residual platelet aggregation (RPA) was evaluated by aggregometry 6 hr after administration of a 600-mg loading dose of clopidogrel. Patients with an RPA of less than 35% were defined as responders.The median calcium score was 736 Agatston score equivalent (ASE) (range, 0-5,772) and mean platelet inhibition was 35% ± 19% (range, 0-70%). A total of 494 coronary plaques were detected (responders: calcified, 197; mixed, 47, noncalcified, 5; and low responders: calcified, 177; mixed, 65; noncalcified, 3). Responders (n = 35) had significantly lower ASEs and fewer mixed but more calcified plaques than did low responders. In mean plaque density (measured within the noncalcified part of the plaques), no statistically significant difference existed between the 2 patient groups. By use of MDCT, we showed that ASE and plaque distribution were associated with RPA after clopidogrel treatment. Patients with a low coronary plaque burden and a small proportion of mixed plaques were more likely to have low RPA after administration of clopidogrel.

Early response assessment in patients with multiple myeloma during anti-angiogenic therapy using arterial spin labelling: first clinical results.

OBJECTIVE: To determine if arterial-spin-labelling (ASL) MRI can reliably detect early response to anti-angiogenic therapy in patients with multiple myeloma by comparison with clinical/haematological response. METHODS: Nineteen consecutive patients (10 men; mean age 63.5 ± 9.1 years) were included in the present study. Inclusion criteria were diagnosis of stage III multiple myeloma and clinical indication for therapeutical administration of bortezomib or lenalidomide. We performed MRI on 3.0T MR in the baseline setting, 3 weeks after onset of therapy and after 8 weeks. Clinical responses were determined on the basis of international uniform response criteria in correlation with haematological parameters and medium-term patient outcome. MRI studies were performed after approval by the local institutional review board. RESULTS: Fifteen patients responded to anti-myeloma therapy; 4/19 patients were non-responders to therapy. Mean tumour perfusion assessed by ASL-MRI in a reference lesion was 220.7 ± 132.5 ml min(-1) 100 g(-1) at baseline, and decreased to 125.7 ± 86.3 (134.5 ± 150.9) ml min(-1) 100 g(-1) 3 (8) weeks after onset of therapy (P < 0.02). The mean decrease in paraproteinaemia at week 3 (8) was 52.3 ± 47.7% (58.2 ± 58.7%), whereas ß2-microglobulinaemia decreased by 20.3 ± 53.1% (23.3 ± 57.0%). Correlation of ASL perfusion with outcome was significant (P = 0.0037). CONCLUSION: ASL tumour perfusion measurements are a valuable surrogate parameter for early assessment of response to novel anti-angiogenic therapy.

Prevalence and clinical characteristics of symptomatic patients with obstructive coronary artery disease in the absence of coronary calcifications.

RATIONALE AND OBJECTIVES: The quantification of coronary calcification has established itself as a valid risk marker to predict cardiovascular events. However, data derived from cardiac multi-detector row computed tomography could demonstrate that the exclusion of coronary calcification is not synonymous with the exclusion of coronary artery disease (CAD). The aims of this retrospective analysis were to determine the prevalence of significant CAD in a symptomatic cohort with indications for invasive angiography but without coronary calcification (Agatston score 0) as assessed by multislice computed tomography and to investigate whether there were any differences in terms of risk factors between patients with and without significant CAD. MATERIALS AND METHODS: Five hundred multislice computed tomographic scans (in 371 men and 129 women) were included in the analysis. Agatston scores were determined on native scans. All patients underwent coronary angiography to detect or rule out obstructive CAD. Patients with negative calcium scoring were selected and divided into two subgroups: those without obstructive CAD and those with obstructive CAD (luminal stenoses > 50%). These subgroups were characterized in terms of clinical characteristics (age and sex) and cardiovascular risk factors (diabetes mellitus, hypertension, hyperlipoproteinemia, familial predisposition, smoking, and overweight). RESULTS: Sixty-one of 500 patients (12.2%) had negative calcium scores (Agatston score 0). Sixteen of these patients (26.3%, or 3.2% of the total population) had obstructive CAD according to invasive angiography. Patients with obstructive CAD were significantly older (mean age, 64 ± 9 vs 55 ± 10 years; P = .003) and were more frequently diabetic (25% vs 4%, P = .0389) than patients without obstructive CAD. There were no significant differences with regard to the other risk factors. CONCLUSIONS: In this high-risk population, the absence of coronary calcification was not sufficient to rule out CAD. Among patients without coronary calcification, the presence of significant CAD was associated with increased age and the presence of diabetes mellitus.

Dual-energy computed tomography: is there a penalty in image quality and radiation dose compared with single-energy computed tomography?

OBJECTIVE: To assess dose and image quality of dual-energy (DE) mixed images in comparison to single-energy (SE) images. METHODS: A phantom containing iodine contrast inserts was scanned using SE and DE protocols. Dual-energy mixed images were reconstructed with varying composition ratios (ratio describing the contribution of 80 and 140 data in the mixed images). Image noise, iodine contrast, and contrast-to-noise ratios (CNRs) were assessed inside and outside the central field of view (FoV). RESULTS: With the default composition ratio (0.3), noise and contrast were comparable between both protocols in the central FoV. Peripherally, DE image noise exceeded noise in SE images; CNR in the periphery was lower in the DE images. The highest CNR was found for a composition ratio of 0.5 to 0.9, exceeding the CNR of SE images. CONCLUSIONS: Dual-energy mixed images offer an image quality comparable to SE images within the central FoV at comparable dose levels. In the peripheral FoV, image quality is decreased. By optimizing the composition ratio in the DE mixed images, higher CNRs than in the SE images can be achieved, leading to a dose reduction potential.