Time to Exhale: Additional Value of Expiratory Chest CT in Chronic Obstructive Pulmonary Disease.

Objectives: Diagnostic guidelines for chronic obstructive pulmonary disease (COPD) are based on spirometry and clinical criteria. However, this does not address the pathophysiological complexity of the disease sufficiently. Until now, inspiratory chest computed tomography (CT) has been considered as the preferred imaging method in these patients. We hypothesized that expiratory CT may be superior to demonstrate pathophysiological changes. The aim of this prospective study was to systematically compare lung function tests with quantified CT parameters in inspiration and expiration. Materials and Methods: Forty-six patients with diagnosed COPD underwent spirometry, body plethysmography, and dose-optimized CT in maximal inspiration and expiration. Four quantified CT parameters were acquired in inspiration, expiration, and their calculated delta values. These parameters were correlated with seven established lung function parameters. Results: For inspiratory scans, a weak-to-moderate correlation with the lung function parameters was found. These correlations significantly improved when adding the expiratory scan (p < 0.05). Moreover, some parameters showed a significant correlation only in expiratory datasets. Calculated delta values showed even stronger correlation with lung function testing. Conclusions: Expiratory quantified CT and calculated delta values significantly improve the correlation with lung function parameters. Thus, an additional expiratory CT may improve image-based phenotyping of patients with COPD.

Lower extremity vasculitis in giant cell arteritis: important differential diagnosis in patients with lower limb claudication.

Most patients with peripheral arterial disease suffer from arteriosclerosis, the prevalence of which increases with age. In some of these patients, however, the ischemic symptoms are not caused by stenotic arteriosclerosis, but by large vessel giant cell arteritis (LV-GCA), a disease also predominantly affecting patients of the older generation. Identifying large vessel vasculitis is a challenge for all physicians caring for patients with peripheral artery disease. The results of invasive treatment such as bypass surgery and angioplasty of inflammatory vascular lesions differ fundamentally from those of patients with atherosclerosis. Duplex ultrasound is a widely available diagnostic method for examining patients with lower limb claudication and pathological ankle-/toe- brachial index or pulse volume recording with or without exercise. Knowledge of characteristic sonographic findings suspicious about large vessel vasculitis is essential for a differential diagnosis of vasculitis versus atherosclerosis. In addition to clinical and laboratory findings, further imaging techniques, e.g. contrast-enhanced computed tomography, magnetic resonance imaging or a combination of positron emission tomography and computed tomography (PET-CT) can provide information on further vessel involvement and inflammatory activity. The present study focuses on diagnostic imaging of LV-GCA in patients presenting with claudication, illustrated by a series of cases.

Brainstem abnormalities and vestibular nerve enhancement in acute neuroborreliosis.

BACKGROUND: Borreliosis is a widely distributed disease. Neuroborreliosis may present with unspecific symptoms and signs and often remains difficult to diagnose in patients with central nervous system symptoms, particularly if the pathognomonic erythema chronica migrans does not develop or is missed. Thus, vigilance is mandatory in cases with atypical presentation of the disease and with potentially severe consequences if not recognized early. We present a patient with neuroborreliosis demonstrating brain stem and vestibular nerve abnormalities on magnetic resonance imaging. CASE PRESENTATION: A 28-year-old Caucasian female presented with headaches, neck stiffness, weight loss, nausea, tremor, and gait disturbance. Magnetic resonance imaging showed T2-weighted hyperintense signal alterations in the pons and in the vestibular nerves as well as bilateral post-contrast enhancement of the vestibular nerves. Serologic testing of the cerebrospinal fluid revealed the diagnosis of neuroborreliosis. CONCLUSION: Patients infected with neuroborreliosis may present with unspecific neurologic symptoms and magnetic resonance imaging as a noninvasive imaging tool showing signal abnormalities in the brain stem and nerve root enhancement may help in establishing the diagnosis.

How to assess non-calcified plaque in CT angiography: delineation methods affect diagnostic accuracy of low-attenuation plaque by CT for lipid-core plaque in histology.

AIMS: To compare the accuracy of two plaque delineation methods for coronary computed tomographic angiography (CTA) to identify lipid-core plaque (LCP) using histology as the reference standard. METHODS AND RESULTS: Five ex vivo hearts were analysed by CTA and histology. LCP was defined by histology as fibroatheroma with core diameter/circumference >200 µm/>60° and cap thickness <450 µm. In CTA, plaque was manually delineated either as the difference between the inner and outer vessel walls (Method A) or as a direct tracing of plaque (Method B). Low-attenuation plaque was defined as an area with <90 Hounsfield units. Of 446 co-registered cross-sections, 55 (12%) contained LCP. In CTA, low-attenuation plaque area was larger as assessed with Method A compared with Method B (difference: 120 ± 60%). Although low-attenuation plaque was associated with the presence of LCP, the delineation Method B yielded higher diagnostic accuracy than Method A [area under the curve (AUC): 0.831 vs. 0.780, respectively, P = 0.005]. After excluding 'normal' cross-sections by CTA (n = 117), AUC for detecting LCP became similar between both methods (0.767 vs. 0.729, P = 0.07, respectively). CONCLUSION: Low-attenuation plaque in CTA is a diagnostic tool for LCP but prone to error if plaque is defined as the area between the inner and outer vessel walls and normal cross-sections are included in the assessment.

Histogram analysis of lipid-core plaques in coronary computed tomographic angiography: ex vivo validation against histology.

PURPOSE: In coronary computed tomographic angiography (CTA), low attenuation of coronary atherosclerotic plaque is associated with lipid-rich plaques. However, an overlap in Hounsfield units (HU) between fibrous and lipid-rich plaque as well as an influence of luminal enhancement on plaque attenuation was observed and may limit accurate detection of lipid-rich plaques by CTA. We sought to determine whether the quantitative histogram analysis improves accuracy of the detection of lipid-core plaque (LCP) in ex vivo hearts by validation against histological analysis. MATERIALS AND METHODS: Human donor hearts were imaged with a 64-slice computed tomographic scanner using a standard coronary CTA protocol, optical coherence tomography (OCT), a histological analysis. Lipid-core plaque was defined in the histological analysis as any fibroatheroma with a lipid/necrotic core diameter of greater than 200 µm and a circumference greater than 60 degrees as well as a cap thickness of less than 450 µm. In OCT, lipid-rich plaque was determined as a signal-poor region with diffuse borders in 2 quadrants or more. In CTA, the boundaries of the noncalcified plaque were manually traced. The absolute and relative areas of low attenuation plaque based on pixels with less than 30, less than 60, and less than 90 HU were calculated using quantitative histogram analysis. RESULTS: From 5 hearts, a total of 446 cross sections were coregistered between CTA and the histological analysis. Overall, 55 LCPs (12%) were identified by the histological analysis. In CTA, the absolute and relative areas of low attenuation plaque less than 30, less than 60, and less than 90 HU were 0.14 (0.31) mm2 (4.22% [9.02%]), 0.69 (0.95) mm2 (18.28% [21.22%]), and 1.35 (1.54) mm2 (35.65% [32.07%]), respectively. The low attenuation plaque area correlated significantly with histological lipid content (lipid/necrotic core size [in square millimeter] and a portion of lipid/necrotic core on the entire plaque) at all thresholds but was the strongest at less than 60 HU (r = 0.53 and r = 0.48 for the absolute and relative areas, respectively). Using a threshold of 1.0 mm2 or greater, the absolute plaque area of less than 60 HU in CTA yielded 69% sensitivity and 80% specificity to detect LCP, whereas sensitivity and specificity were 73% and 71% for using 25.0% or higher relative area less than 60 HU. The discriminatory ability of CTA for LCP was similar between the absolute and relative areas (the area under the curve, 0.744 versus 0.722; P = 0.37). Notably, the association of the low attenuation plaque area in CTA with LCP was not altered by the luminal enhancement for the relative (P = 0.48) but for the absolute measurement (P = 0.03). Similar results were achieved when validated against lipid-rich plaque by OCT in a subset of 285 cross sections. CONCLUSIONS: In ex vivo conditions, the relative area of coronary atherosclerotic plaque less than 60 HU in CTA as derived from quantitative histogram analysis has good accuracy to detect LCP as compared with a histological analysis independent of differences in luminal contrast enhancement.

The napkin-ring sign indicates advanced atherosclerotic lesions in coronary CT angiography.

OBJECTIVES: This study sought to determine the accuracy of plaque pattern assessment by coronary computed tomography angiography (CCTA) to differentiate between early and advanced atherosclerotic lesions as defined by histology. BACKGROUND: A ringlike attenuation pattern of coronary atherosclerotic plaques termed as napkin-ring sign (NRS) was described in CCTA of patients who had acute coronary syndrome. METHODS: All procedures were performed in accordance with local and federal regulations and the Declaration of Helsinki. Approval of the local ethics committees was obtained. We investigated 21 coronary arteries of 7 donor hearts. Overall, 611 histological sections were obtained and coregistered with CCTA images. The CCTA cross sections were read in random order for conventional plaque categories (noncalcified [NCP], mixed [MP], calcified [CP]) and plaque patterns (homogenous, heterogeneous with no napkin-ring sign [non-NRS], and heterogeneous with NRS). RESULTS: No plaque was detected in 134 (21.9%), NCP in 254 (41.6%), MP in 191 (31.3%), and CP in 32 (5.2%) CCTA cross sections. The NCP and MP were further classified into homogenous plaques (n = 207, 46.5%), non-NRS plaques (n = 200, 44.9%), and NRS plaques (n = 38, 8.6%). The specificities of NCP and MP to identify advanced lesions were moderate (57.9%, 95% confidence interval [CI]: 50.1% to 65.6%, and 72.1%, 95% CI: 64.7% to 79.4%, respectively), which were similar to the homogenous and heterogeneous plaques (62.6%, 95% CI: 54.8% to 70.3%, and 67.3%, 95% CI: 58.6% to 76.1%, respectively). In contrast, the specificity of the NRS to identify advanced lesions was excellent (98.9%, 95% CI: 97.6% to 100%). The diagnostic performance of the pattern-based scheme to identify advanced lesions was significantly better than that of the conventional plaque scheme (area under the curve: 0.761 vs. 0.678, respectively; p = 0.001). CONCLUSIONS: The assessment of the plaque pattern improves diagnostic accuracy of CCTA to identify advanced atherosclerotic lesions. The CCTA finding of NRS has a high specificity and high positive predictive value for the presence of advanced lesions.

Differentiation of early from advanced coronary atherosclerotic lesions: systematic comparison of CT, intravascular US, and optical frequency domain imaging with histopathologic examination in ex vivo human hearts.

PURPOSE: To establish an ex vivo experimental setup for imaging coronary atherosclerosis with coronary computed tomographic (CT) angiography, intravascular ultrasonography (US), and optical frequency domain imaging (OFDI) and to investigate their ability to help differentiate early from advanced coronary plaques. MATERIALS AND METHODS: All procedures were performed in accordance with local and federal regulations and the Declaration of Helsinki. Approval of the local Ethics Committee was obtained. Overall, 379 histologic cuts from nine coronary arteries from three donor hearts were acquired, coregistered among modalities, and assessed for the presence and composition of atherosclerotic plaque. To assess the discriminatory capacity of the different modalities in the detection of advanced lesions, c statistic analysis was used. Interobserver agreement was assessed with the Cohen κ statistic. RESULTS: Cross sections without plaque at coronary CT angiography and with fibrous plaque at OFDI almost never showed advanced lesions at histopathologic examination (odds ratio [OR]: 0.02 and 0.06, respectively; both P<.0001), while mixed plaque at coronary CT angiography, calcified plaque at intravascular US, and lipid-rich plaque at OFDI were associated with advanced lesions (OR: 2.49, P=.0003; OR: 2.60, P=.002; and OR: 31.2, P<.0001, respectively). OFDI had higher accuracy for discriminating early from advanced lesions than intravascular US and coronary CT angiography (area under the receiver operating characteristic curve: 0.858 [95% confidence interval {CI}: 0.802, 0.913], 0.631 [95% CI: 0.554, 0.709], and 0.679 [95% CI: 0.618, 0.740]; respectively, P<.0001). Interobserver agreement was excellent for OFDI and coronary CT angiography (κ=0.87 and 0.85, respectively) and was good for intravascular US (κ=0.66). CONCLUSION: Systematic and standardized comparison between invasive and noninvasive modalities for coronary plaque characterization in ex vivo specimens demonstrated that coronary CT angiography and intravascular US are reasonably associated with plaque composition and lesion grading according to histopathologic findings, while OFDI was strongly associated. These data may help to develop initial concepts of sequential imaging strategies to identify patients with advanced coronary plaques.

Liver fat quantification by dual-echo MR imaging outperforms traditional histopathological analysis.

RATIONALE AND OBJECTIVES: The aim of this study was to evaluate the accuracy of dual-echo (DE) magnetic resonance imaging (MRI) with and without fat and water separation for the quantification of liver fat content (LFC) in vitro and in patients undergoing liver surgery, with comparison to histopathologic analysis. MATERIALS AND METHODS: MRI was performed on a 1.5-T scanner using a three-dimensional DE MRI sequence with automated reconstruction of in-phase (IP) and out-of-phase (OP) and fat-signal-only and water-signal-only images. LFC was estimated by fat fractions from IP and OP images (MRI(IP/OP)) and from Dixon-based fat-only and water-only images (MRI(DIxON)). Seven phantoms containing a titrated mixture of liver and fat from 0% to 50% were examined. Forty-three biopsies in 22 patients undergoing liver surgery were prospectively evaluated by a pathologist by traditional determination of the cell-count fraction and by a computer-based algorithm, the latter serving as the reference standard. RESULTS: In vitro, both MRI(IP/OP) and MRI(DIxON) were significantly correlated with titrated LFC (r = 0.993, P < .001), with a smaller measurement bias for MRI(IP/OP) (+2.6%) than for MRI(DIxON) (+4.5%). In vivo, both MRI(IP/OP) and MRI(DIxON) from DE MRI were correlated significantly better with computer-based histologic results (P < .001) and showed significantly smaller measurement bias (4.8% vs 21.1%) compared to histologic cell-count fraction (P < .001). Measurement bias was significantly smaller for MRI(IP/OP) than for MRI(DIxON) (P < .001). CONCLUSIONS: DE MRI allows the accurate quantification of LFC in a surgical population, outperforming traditional histopathologic analysis. DE MRI without fat and water separation shows the highest accuracy and smallest measurement bias for the quantification of LFC.

Variability and accuracy of coronary CT angiography including use of iterative reconstruction algorithms for plaque burden assessment as compared with intravascular ultrasound-an ex vivo study.

OBJECTIVES: To systematically assess inter-technique and inter-/intra-reader variability of coronary CT angiography (CTA) to measure plaque burden compared with intravascular ultrasound (IVUS) and to determine whether iterative reconstruction algorithms affect variability. METHODS: IVUS and CTA data were acquired from nine human coronary arteries ex vivo. CT images were reconstructed using filtered back projection (FBPR) and iterative reconstruction algorithms: adaptive-statistical (ASIR) and model-based (MBIR). After co-registration of 284 cross-sections between IVUS and CTA, two readers manually delineated the cross-sectional plaque area in all images presented in random order. RESULTS: Average plaque burden by IVUS was 63.7 ± 10.7% and correlated significantly with all CTA measurements (r = 0.45-0.52; P < 0.001), while CTA overestimated the burden by 10 ± 10%. There were no significant differences among FBPR, ASIR and MBIR (P > 0.05). Increased overestimation was associated with smaller plaques, eccentricity and calcification (P < 0.001). Reproducibility of plaque burden by CTA and IVUS datasets was excellent with a low mean intra-/inter-reader variability of <1/<4% for CTA and <0.5/<1% for IVUS respectively (P < 0.05) with no significant difference between CT reconstruction algorithms (P > 0.05). CONCLUSION: In ex vivo coronary arteries, plaque burden by coronary CTA had extremely low inter-/intra-reader variability and correlated significantly with IVUS measurements. Accuracy as well as reader reliability were independent of CT image reconstruction algorithm. KEY POINTS: • IVUS is deemed the gold standard in-vivo coronary plaque assessment • But coronary CT angiography findings correlate strongly with IVUS results • Coronary CT angiography now allows plaque quantification close to IVUS • Iterative image reconstruction algorithms do not alter accuracy or reproducibility • Plaque quantification is more challenging in smaller eccentric calcified lesions.

Ventricular short-axis measurements in patients with pulmonary embolism: effect of ECG-gating on variability, accuracy, and risk prediction.

OBJECTIVE: To assess prospectively the intra- and interobserver variability, accuracy, and prognostic value of right and left ventricular short-axis diameter (RVd and LVd) measurements for risk stratification in patients with pulmonary embolism (PE) using ECG-gated compared to non-gated CT. MATERIALS AND METHODS: Sixty consecutive patients (33 women; mean age 58.7±10.3 years) with suspicion of PE underwent both non-gated and ECG-gated chest CT. RVd and LVd on four-chamber views and intra- and interobserver agreements were calculated for both protocols. RVd/LVd ratios were calculated and were related to 30-days adverse clinical events using receiver operating characteristics with area-under-the-curve (AUC) analyses. RESULTS: Both inter- and intraobserver variability showed narrower limits of agreement for all measurements with ECG-gated as compared to non-gated CT. Diameter measurements were significantly lower using non-ECG-gated CT as compared to ECG-gated CT for RVd and LVd (both p<.05). The AUC for the RVd/LVd ratio from ECG-gated CT was significantly larger than that from non-gated CT (0.956, 95% CI: 0.768-0.999 versus 0.675, 95% CI: 0.439-0.860; p=.048). CONCLUSION: RVd and LVd measurements from ECG-gated chest CT show less intra- and interobserver variability and more accurately reflect ventricular function. In our patient cohort ECG-gated chest CT allows better prediction of short-term outcome of patients with acute PE that needs to be validated in a larger outcome study.

Coronary artery plaques: cardiac CT with model-based and adaptive-statistical iterative reconstruction technique.

OBJECTIVES: To compare image quality of coronary artery plaque visualization at CT angiography with images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model based iterative reconstruction (MBIR) techniques. METHODS: The coronary arteries of three ex vivo human hearts were imaged by CT and reconstructed with FBP, ASIR and MBIR. Coronary cross-sectional images were co-registered between the different reconstruction techniques and assessed for qualitative and quantitative image quality parameters. Readers were blinded to the reconstruction algorithm. RESULTS: A total of 375 triplets of coronary cross-sectional images were co-registered. Using MBIR, 26% of the images were rated as having excellent overall image quality, which was significantly better as compared to ASIR and FBP (4% and 13%, respectively, all p<0.001). Qualitative assessment of image noise demonstrated a noise reduction by using ASIR as compared to FBP (p<0.01) and further noise reduction by using MBIR (p<0.001). The contrast-to-noise-ratio (CNR) using MBIR was better as compared to ASIR and FBP (44±19, 29±15, 26±9, respectively; all p<0.001). CONCLUSIONS: Using MBIR improved image quality, reduced image noise and increased CNR as compared to the other available reconstruction techniques. This may further improve the visualization of coronary artery plaque and allow radiation reduction.

Complementary value of cardiac FDG PET and CT for the characterization of atherosclerotic disease.

For decades, the identification of significant luminal narrowing has been the hallmark to characterize the presence and extent of coronary artery disease. However, it is now known that characterizations of systemic atherosclerosis burden and inflammation, as well as the local quality of plaque composition and morphology, allow better characterization of coronary artery disease and thus may allow improved prediction of adverse cardiovascular events. Plaque characterized histologically as a thin-cap fibroatheroma (ie, an atheroma with a thin fibrous cap, an underlying lipid-rich necrotic core, and inflammatory activity) has been recognized as representing vulnerable or high-risk plaque. Positron emission tomography (PET) and cardiac computed tomography (CT) are noninvasive modalities that provide metabolic (PET) and morphologic (CT) information about atherosclerotic plaque. PET allows the quantification of the uptake of fluorine 18 fluorodeoxyglucose (FDG) within the arterial wall, which provides a measure of macrophage activity within atheromatous plaque. Coronary CT allows the depiction of plaque morphology and composition. Thus, integrated imaging with PET and CT (PET/CT) permits coregistration of FDG activity with the presence and morphology of plaque and may lead to improved characterization of vulnerable plaque or vulnerable patients, or both. This review details the methods and principles of cardiac FDG PET and coronary CT and provides an overview of the research, with an emphasis on the identification and characterization of vulnerable plaque.

Adenosine stress high-pitch 128-slice dual-source myocardial computed tomography perfusion for imaging of reversible myocardial ischemia: comparison with magnetic resonance imaging.

BACKGROUND: Coronary computed tomography angiography (CTA) enables accurate anatomic evaluation of coronary artery stenosis but lacks information about hemodynamic significance. The aim of this study was to evaluate 128-slice myocardial CT perfusion (CTP) imaging with adenosine stress using a high-pitch mode, in comparison with cardiac MRI (CMR). METHODS AND RESULTS: Thirty-nine patients with intermediate to high coronary risk profile underwent adenosine stress 128-slice dual source CTP (128×0.6 mm, 0.28 seconds). Among those, 30 patients (64 ± 10 years, 6% women) also underwent adenosine stress CMR (1.5T). The 2-step CTP protocol consisted of (1) adenosine stress-CTP using a high-pitch factor (3.4) ECG-synchronized spiral mode and (2) rest-CTP/coronary-CTA using either high-pitch (heart rate <63 bpm) or prospective ECG-triggering (heart rate >63 bpm). Results were compared with CMR and with invasive angiography in 25 patients. The performance of stress-CTP for detection of myocardial perfusion defects compared with CMR was sensitivity, 96%; specificity, 88%; positive predictive value (PPV), 93%; negative predictive value (NPV), 94% (per vessel); and sensitivity, 78%; specificity, 87%; PPV, 83%; NPV, 84% (per segment). The accuracy of stress-CTP for imaging of reversible ischemia compared with CMR was sensitivity, 95%; specificity, 96%; PPV, 95%; and NPV, 96% (per vessel). In 25 patients who underwent invasive angiography, the accuracy of CTA for detection of stenosis >70% was (per segment): sensitivity, 96%; specificity, 88%; PPV, 67%; and NPV, 98.9%. The accuracy improved from 84% to 95% after adding stress CTP to CTA. Radiation exposure of the entire stress/rest CT protocol was only 2.5 mSv. CONCLUSIONS: Adenosine-induced stress 128-slice dual-source high-pitch myocardial CTP allows for simultaneously assessment of reversible myocardial ischemia and coronary stenosis, with good diagnostic accuracy as compared with CMR and invasive angiography, at a very low radiation exposure.

Molecular imaging of malignant tumor metabolism: whole-body image fusion of DWI/CT vs. PET/CT.

PURPOSE: To prospectively investigate the technical feasibility and performance of image fusion for whole-body diffusion-weighted imaging (wbDWI) and computed tomography (CT) to detect metastases using hybrid positron emission tomography/computed tomography (PET/CT) as reference standard. MATERIAL AND METHODS: Fifty-two patients (60 ± 14 years; 18 women) with different malignant tumor disease examined by PET/CT for clinical reasons consented to undergo additional wbDWI at 1.5 Tesla. WbDWI was performed using a diffusion-weighted single-shot echo-planar imaging during free breathing. Images at b = 0 s/mm(2) and b = 700 s/mm(2) were acquired and apparent diffusion coefficient (ADC) maps were generated. Image fusion of wbDWI and CT (from PET/CT scan) was performed yielding for wbDWI/CT fused image data. One radiologist rated the success of image fusion and diagnostic image quality. The presence or absence of metastases on wbDWI/CT fused images was evaluated together with the separate wbDWI and CT images by two different, independent radiologists blinded to results from PET/CT. Detection rate and positive predictive values for diagnosing metastases was calculated. PET/CT examinations were used as reference standard. RESULTS: PET/CT identified 305 malignant lesions in 39 of 52 (75%) patients. WbDWI/CT image fusion was technically successful and yielded diagnostic image quality in 73% and 92% of patients, respectively. Interobserver agreement for the evaluation of wbDWI/CT images was κ = 0.78. WbDWI/CT identified 270 metastases in 43 of 52 (83%) patients. Overall detection rate and positive predictive value of wbDWI/CT was 89% (95% CI, 0.85-0.92) and 94% (95% CI, 0.92-0.97), respectively. CONCLUSION: WbDWI/CT image fusion is technically feasible in a clinical setting and allows the diagnostic assessment of metastatic tumor disease detecting nine of 10 lesions as compared with PET/CT.

Coronary artery plaques and myocardial ischaemia.

OBJECTIVE: To prospectively examine coronary artery plaques as predictors of myocardial ischaemia using cardiac magnetic resonance (CMR). METHODS: Fifty-two patients (46 men; age 64 ± 10) with suspected coronary artery disease (CAD) referred for catheter coronary angiography (CA) underwent CMR and computed tomography coronary angiography (CTCA). All coronary segments were evaluated for morphological stenosis based on CA. Any plaque according to its composition was assessed based on CTCA. RESULTS: Numbers of total and calcified coronary artery plaques represented the best predictors of myocardial ischaemia (AUC = 0.87; [95%CI: 0.77-0.97] and AUC = 0.87; [95%CI: 0.77-0.96], respectively, p = 0.56) with the total plaque number significantly higher in patients with corresponding ischaemia than those without (p < 0.01, p < 0.05 adjusted for pre-test probability and stenosis). Compared with the AUC of coronary stenosis assessment by CA (AUC = 0.90; [95%CI: 0.80-1.00]), AUCs were equivalent using either the total number or the number of calcified plaques alone (p = 0.73 and p = 0.69). Multivariate logistic regression analyses demonstrated the total plaque number as an independent predictor of ischaemia (odds +20%; [95%CI: 1.096-1.368]), improving a model including clinical probability estimates of CAD (c-statistics, 0.66 to 0.89). CONCLUSION: Coronary artery plaque number according to CTCA is a significant, independent predictor of myocardial ischaemia with similar accuracy to stenosis assessment.

Quantification of aortic regurgitant fraction and volume with multi-detector computed tomography comparison with echocardiography.

RATIONALE AND OBJECTIVES: Evaluate quantification of the aortic regurgitant fraction and volume with computed tomography (CT). MATERIALS AND METHODS: Fifty-three patients with aortic regurgitation (AR) and 29 controls were examined with 64-multi-detector CT coronary angiography and transthoracic echocardiography (TTE). A dedicated software algorithm employing three-dimensional segmentation of left ventricle (LV) and right ventricle (RV) volumes and LV mass was applied. AR volume and fraction was calculated based on RV and LV stroke volumes (SV) and compared with echocardiography. The aortic regurgitant orifice area (ROA) was measured by CT. RESULTS: A good correlation of the AR fraction and AR volume determined by CT compared to echocardiography was found for mild, moderate, and severe AR with 14.2% ± 9, 28.8% ± 8, and 57.9% ± 9 (r = 0.95, P < .001) for AR fraction, and 15.7 mL ± 11.33 mL ± 14, and 98.9 mL ± 36 for AR volume (r = 0.92, P < .0001), respectively. CT correctly classified severity of AR in 93% of patients based of AR-fraction, and in 89% based on AR volume. The sensitivity and specificity of CT were 98% and specificity 90.3%. The specificity improved to 97%, if the ROA by CT was added as diagnostic criterion. CONCLUSION: Aortic regurgitation fraction and volume can be accurately quantified from CT coronary angiography datasets. These parameters can assist clinical management, e.g. in case of pending cardiac surgery decision.

3D fusion of functional cardiac magnetic resonance imaging and computed tomography coronary angiography: accuracy and added clinical value.

PURPOSE: To evaluate the accuracy and added diagnostic value of 3-dimensional (3D) image fusion of computed tomography coronary angiography (CTCA) and functional cardiac magnetic resonance (CMR) for assessing hemodynamically relevant coronary artery disease (CAD). METHODS: Twenty-seven patients with significant coronary stenoses on prospectively electrocardiography-gated dual-source CTCA, confirmed by catheter angiography and perfusion defects on CMR at 1.5 T were included. Surface representations and volume-rendered images from 3D-fused CTCA/CMR data were generated using a software prototype. Fusion accuracy was evaluated by calculating surface distances of blood pools and Dice similarity coefficients. Two independent, blinded readers assigned myocardial defects to culprit coronary arteries with side-by side analysis of CTCA and CMR and using fused CTCA/CMR. Added value of fused CTCA/CMR was defined as change in assignment of culprit coronary artery to myocardial defect compared with side-by-side analysis. RESULTS: 3D fusion of CTCA/CMR was feasible and accurate (surface distance of blood pools: 4.1 ± 1.3 mm, range: 2.4-7.1 mm; Dice similarity coefficients: 0.78 ± 0.08, range: 0.51-0.86) in all patients. Side-by-side analysis of CTCA and CMR allowed no assignment of a single culprit artery to a myocardial defect in 6 of 27 (22%) patients. Fused CTCA/CMR allowed further confinement of culprit coronary arteries in 3 of these 6 patients (11%). Myocardial defects were reassigned in 2 of 27 (7%) patients using fused CTCA/CMR, whereas the results remained unchanged in 22 of 27 (81%) patients. Interobserver agreement for assignment of culprit arteries to myocardial defects increased with fused CTCA/CMR (k = 0.66-0.89). CONCLUSION: 3D fusion of low-dose CTCA and functional CMR is feasible and accurate, and adds, at a low radiation dose, diagnostic value for the assessment of hemodynamically relevant CAD as compared with side-by-side analysis alone. This technique can be clinically useful for the following: planning of surgical or interventional procedures in patients having a high prevalence of CAD and for improved topographic assignment of coronary stenoses to corresponding myocardial perfusion defects.

Computed tomography of the lung in the high-pitch mode: is breath holding still required?

OBJECTIVES: To prospectively investigate whether the high-pitch mode (HPM) for computed tomography (CT) enables the diagnostic visualization of the lung parenchyma without suspended respiration. MATERIALS AND METHODS: A total of 40 consecutive patients (age, 67 ± 11 years) underwent 128-slice dual-source CT of the chest including nonenhanced, arterial, and venous phase of contrast. CT was performed in the HPM with a pitch of 3.2 during continuous breathing (group A) and during breath-hold (group B), and at standard pitch of 1 during deep-inspiratory breath-hold (group C). The 3 protocols were scanned in a random order in each patient. Two blinded readers independently assessed the image quality of 5 regions in both the lungs using a semiquantitative 3-point score. Image noise was measured as the standard deviation of attenuation. Presence and size of pulmonary nodules were noted and measured on each CT dataset. Lung volume was measured using dedicated semi-automated segmentation software. RESULTS: Interobserver agreement for image quality ratings was excellent (κ = 0.91). There were no significant differences in the number of lung regions having an image quality other than excellent between group A (2.5%) and B (1.5%, P = 0.48), whereas significantly less regions had impaired image quality in group B compared with group C (5.5%, P < 0.01). Image quality impairment in group C was because of breathing in 36% and cardiac pulsation in 64%. Image noise in group C (9 ± 2 HU) was significantly lower than that in group B (30 ± 2 HU, P < 0.001) whereas no significant difference was found between group A and B (P = 0.52). There were no significant differences for the depiction (P = 1.0) and size (P = 0.94) of lung nodules among the 3 modes. Average lung volume in group A was 75% ± 15% of that in deep inspiration (group B/C) being significantly smaller (P < 0.05). Estimated effective radiation doses in group C and group B were 5.8 ± 0.5 mSv and 1.6 ± 0.1 mSv, respectively. CONCLUSIONS: CT of the lung can be accomplished using the HPM at a low radiation dose with a diagnostic image quality even without suspended respiration.

Coronary artery disease: which degree of coronary artery stenosis is indicative of ischemia?

PURPOSE: To prospectively determine the best cut-off value of stenosis degree for low-dose computed tomography coronary angiography (CTCA) to predict the hemodynamic significance of coronary artery stenoses compared to catheter angiography (CA) using a cardiac magnetic resonance based approach as standard of reference. MATERIALS AND METHODS: Fifty-two patients (mean age, 64±10 years) scheduled for CA underwent cardiac magnetic resonance (CMR) at 1.5-T and dual-source CTCA using prospective ECG-triggering the same day. Diagnostic performance of CTCA and CA to detect myocardial ischemia was evaluated with CMR as the standard of reference. The diagnostic performance and best cut-off values to predict the hemodynamic significance of coronary were determined from receiver operating characteristics analysis (ROC). RESULTS: CA revealed >50% stenoses in 131/832 segments (15.7%) in 78/156 (50.0%) coronary arteries in 32/52 (62%) patients. CTCA revealed >50% stenoses in 148/807 (18.3%) segments, corresponding to 83/156 (53.2%) coronary arteries in 34/52 (65.4%) patients. CMR revealed ischemia in 118/832 (14.2%) myocardial segments corresponding to the territories of 60/156 (38.5%) coronary arteries in 29/52 (56%) patients. ROC analysis showed equal diagnostic performance for low-dose CTCA and CA with areas under the curve (AUC) of 0.82 and 0.83 (P=0.64). The optimal cut-off value was determined at stenosis of >60% for the prediction of hemodynamically significant coronary stenosis by CTCA. Using this cut-off value, sensitivity, specificity, NPV and PPV to predict hemodynamic significance by CTCA were 100%, 83%, 100%, and 88% on a per-patient basis and 88%, 73%, 83% and 81% on a per-artery analysis, respectively. CONCLUSION: By considering coronary stenosis >60%, diagnostic performance for predicting the hemodynamic significance of coronary stenosis by CTCA is optimal and equals that of CA.