Purpose: To determine the risk-stratification ability of plaque volume and composition assessment with cardiac computed tomographic (CT) angiography and high-sensitivity troponin T (hsTnT) in patients at intermediate risk for coronary artery disease (CAD).Materials and Methods: The study complied with the Declaration of Helsinki and was approved by the local ethics committee. All patients gave written informed consent. Five hundred twenty-one consecutive patients (mean age 6 standard deviation, 62 years +/- 10; 256 men and 265 women) were included in this prospective, observational, longitudinal, single-center study. Quantitative cardiac CT angiography analysis was performed in all patients (for 7690 coronary segments), whereas biomarkers (hsTnT and high-sensitivity C-reactive protein) were available in 408 patients (78%). To evaluate the incremental value of cardiac CT angiography and hsTnT for the prediction of cardiovascular events, multivariate Cox regression and integrated discrimination improvement analysis were applied.Results: In 521 patients, 13 hard cardiac events occurred during a mean follow-up period of 2.3 years +/- 1.1 (median, 2.4 years; range, 0.5-4.5 years), while 23 patients underwent late coronary revascularization. The Duke clinical score was 51% +/- 30, indicating intermediate risk. The presence of no plaques or purely calcified versus noncalcified plaques, plaque volume according to tertiles, and increased hsTnT (>= 14 pg/mL) was independently associated with hard cardiac events (hazard ratio [HR] = 26.08, 95% confidence interval [CI]: 2.78, 244.99; HR = 12.14, 95% CI: 1.87, 78.74; and HR = 10.31, 95% CI: 2.72, 39.0, respectively; P < .01 for all). Patients with increased hsTnT and plaque burden (n = 53) showed the highest incidence for hard cardiac events (annual rate, 12.7%), followed by those with either increased hsTnT or plaque burden (n = 145; annual rate = 0.44%, P < .03), while those with lower hsTnT and plaque burden exhibited excellent outcomes and no hard event during the follow-up duration (n = 210; annual rate = 0%, P < .001).Conclusion: Use of hsTnT as a marker of myocardial microinjury and cardiac CT angiography as a marker of the total atherosclerotic burden improves the prediction of cardiac outcome in patients with presumably stable CAD and may aid in personalized risk stratification in patients at intermediate risk. (C) RSNA, 2015

PURPOSE:To evaluate dual-energy CT (DECT) imaging of hypodense liver lesions in patients with hepatic steatosis, having a high incidence in the general population and among cancer patients receiving chemotherapy.METHODS:One hundred and five patients with hepatic steatosis (liver parenchyma <40 HU) underwent contrast-enhanced DECT with reconstruction of pure iodine (PI), optimum contrast (OC), 80 kVp, and 120 kVp-equivalent data sets. Image noise (IN), lesion to liver signal to noise (SNR) and contrast to noise (CNR) ratios were quantitatively analysed; image quality was rated on a 5-point scale (1, excellent; 2, good; 3, fair; 4, poor; 5, non-diagnostic) by two independent reviewers.RESULTS:In 21 patients with hypodense liver lesions, IN was lowest in PI followed by 120 kVp-equivalent and OC, and highest in 80 kVp. SNR was highest in PI (1.30), followed by 120 kVp-equivalent (0.72) and 80 kVp (0.63), and lowest in OC (0.55). CNR was highest in 120 kVp-equivalent (4.95), followed by OC (4.55) and 80 kVp (4.14), and lowest in PI (3.63). The 120 kVp-equivalent series exhibited best overall qualitative image score (1.88), followed by OC (1.98), 80 kVp (3.00) and PI (3.67).CONCLUSION:In our study, the 120 kVp-equivalent series was best suited for visualization of hypodense lesions within steatotic liver parenchyma, while using DECT currently seems to offer no additional diagnostic advantage.KEY POINTS:• Hepatic steatosis has high incidence in the general population and following chemotherapy. • Hypodense liver lesions can be obscured by steatotic liver parenchyma in CT. • Low kV p -CT shows no advantage in detecting hypodense lesions in steatotic livers. • Additional DECT image information does not improve visualization of hypodense lesions in steatosis. • 120 kV p -equivalent imaging yields best quantitative and qualitative image analysis results.

BACKGROUND:There is a high probability for presence of irregular heart rates and artifacts in patients with previous coronary artery bypass graft (CABG) surgery. Previously reported diagnostic performance of ECG-gated 64-slice dual-source computer tomography angiography (CTA) in this patient group is based on pre-selection for normal heart rate and routine clinical setting.PURPOSE:To investigate image quality and diagnostic performance of CTA in patients with previous CABG surgery in various clinical settings.MATERIAL AND METHODS:Fifty-six non-selected, consecutive patients (110 grafts, 44 arterial, 66 venous) with previous CABG surgery were prospectively examined using a dual-source 64-slice CT (Siemens Definition, Forchheim, Germany) without utilization of CT-related pharmaceutical heart rate control. Patients were stratified according to the clinical setting: planned redo-cardiac surgery; emergency CTA within 30 days after CABG surgery; routine follow-up after CABG surgery. A reference standard was available for 30 patients (53.6%; 67/110 grafts). Image quality, artifacts, and graft patency were independently assessed by two observers.RESULTS:All CTAs were diagnostic despite the presence of irregular heart rhythm (25% of cases) and artifacts (72.7% of grafts). CTA was accurate in all patient groups in assessing graft patency (97.9% sensitivity; 100% specificity; 98.5% accuracy) but artifacts decreased diagnostic performance for stenosis detection (60% sensitivity; 88.6% specificity; 84.1% accuracy). Arterial grafts exhibited more surgical clip artifacts compared to venous grafts, which predominantly showed motion artifacts. Overall diagnostic quality was rated excellent in 70.9%/56.4%, good in 23.4%/39.1%, and sufficient in 5.5%/4.5% by each observer, respectively. CTA detected acute findings in 10 cases (graft bleeding, graft occlusion, pericardial hematoma, sternal instability with retrosternal abscess formation, pericardial effusion, left ventricle thrombus) in the emergency group; seven cases required surgical revision.CONCLUSION:Dual-source CTA is a robust and accurate method for assessment of graft patency and detection of relevant extra-cardiac pathologies in a non-selected patient population after CABG surgery in routine as well as emergency clinical settings. Artifacts caused by irregular heart rhythm or surgical clips do not impair graft patency evaluation but limit stenosis assessment.

BACKGROUND:The important detection of in-stent restenosis in cardiovascular computed tomography (CT) is still challenging. The first study assessing the in-vitro stent lumen visualization of the state of the art 256-multislice CT (256-MSCT), which was performed by our research group, yielded promising results. As the applied technical approach is not suitable for daily routine, we assessed the capability of the 256-MSCT and its different reconstruction kernels for the coronary stent lumen visualization employing a clinically applicable technique in a phantom study. RESULTS:The XCD kernel showed significantly lower artificial lumen narrowing (ALN) values (overall ALN < 40%) than the other reconstruction kernels (CC, CD, XCB) irrespective of the stent caliber. The ALN of coronary stents with a diameter >3 mm was significantly lower than of stents with a smaller caliber. The ALN difference between stents with a diameter of 3 mm and smaller ones was not statistically significant. Yet, the lumen visualization of the smaller stents was impaired by a halo effect. The XCD kernel showed more constant attenuation values throughout the different stent diameters than the other reconstruction kernels. CONCLUSIONS:The 256-MSCT provides a good lumen visualization of coronary stents with a diameter >3 mm. The assessment of stents with a diameter of 3 mm seems feasible but has to be validated in further studies. The clinical evaluation of smaller stents cannot be recommended so far. The XCD kernel showed the best lumen visualization and should therefore be applied in addition to the standard cardiac reconstruction kernels when assessing coronary artery stents using 256-MSCT.

PURPOSE:The aim of this study is twofold: to determine the complication rate in computed tomography (CT)-guided biopsies and drainages, and to evaluate the value of postinterventional CT control scans.METHODS:Retrospective analysis of 1,067 CT-guided diagnostic biopsies (n = 476) and therapeutic drainages (n = 591) in thoracic (n = 37), abdominal (n = 866), and musculoskeletal (ms) (n = 164) locations. Severity of any complication was categorized as minor or major. To assess the need for postinterventional CT control scans, it was determined whether complications were detected clinically, on peri-procedural scans or on postinterventional scans only.RESULTS:The complication rate was 2.5 % in all procedures (n = 27), 4.4 % in diagnostic punctures, and 1.0 % in drainages; 13.5 % in thoracic, 2.0 % in abdominal, and 3.0 % in musculoskeletal procedures. There was only 1 major complication (0.1 %). Pneumothorax (n = 14) was most frequent, followed by bleeding (n = 9), paresthesia (n = 2), material damage (n = 1), and bone fissure (n = 1). Postinterventional control acquisitions were performed in 65.7 % (701 of 1,067). Six complications were solely detectable in postinterventional control acquisitions (3 retroperitoneal bleeds, 3 pneumothoraces); all other complications were clinically detectable (n = 4) and/or visible in peri-interventional controls (n = 21).CONCLUSION:Complications in CT-guided interventions are rare. Of these, thoracic interventions had the highest rate, while pneumothoraces and bleeding were most frequent. Most complications can be detected clinically or peri-interventionally. To reduce the radiation dose, postinterventional CT controls should not be performed routinely and should be restricted to complicated or retroperitoneal interventions only.

Purpose: To investigate the value of 4 different protocols for prospectively triggered 256-slice coronary computed tomography angiography (coronary CTA).Methods: Two hundred and ten patients underwent prospectively triggered coronary CTA for suspected or known coronary artery disease (CAD). Patients with heart rate >75 bps before the scan despite beta-blocker administration and with arrhythmia were excluded. From January to September 2010, 60 patients underwent coronary CTA using a non-tailored protocol (120 kV; 200 mAs) and served as our 'control' group. From September 2010 to April 2012, based on the body mass index (BMI) of the examined patients (BMI subgroups of < 25; 25-28; 28-30, and >= 30 kg/m(2)) current tube voltage and tube current were: (1) slightly, (2) moderately or (3) strongly reduced, resulting into the 3 following BMI-adapted acquisition groups: (1) a 'standard' (100/120 kV; 100-200 mAs; n = 50), 2) a 'low dose' (100/120 kV; 75-150 mAs; n = 50), and 3) an 'ultra-low dose' (100/120 kV; 50-100 mAs; n = 50) protocol.Results: Patients examined using the non-tailored protocol exhibited the highest radiation exposure (3.2 +/- 0.4 mSv), followed by the standard (1.6 +/- 0.7 mSv), low-dose (1.2 +/- 0.6 mSv) and ultra-low dose protocol (0.7 +/- 0.3 mSv) (radiation savings of 50%, 63% and 78% respectively). Overall image quality was similar with standard dose (1.9 +/- 0.6) and low-dose (2.0 +/- 0.5) compared to the non-tailored group (1.9 perpendicular to 0.5) (p = NS for all). In the ultra-low dose group however, image quality was significant reduced (2.7 +/- 0.6), p < 0.05 versus all other groups).Conclusion: Using BMI-adapted low dose acquisitions image quality can be maintained with simultaneous radiation savings of similar to 65% (dose of similar to 1 mSv). This appears to be the lower limit for diagnostic coronary CTA, whereas ultra-low dose acquisitions result in significant image degradation. (c) 2012 Elsevier Ireland Ltd. All rights reserved.

Multidetector computed tomography (MDCT) has become the imaging method of choice in patients suspected of having pulmonary embolism (PE) but has the inherent limitation of radiation dose and the side effects of contrast agents. The purpose of the study was to assess the feasibility of a stepwise MRI protocol in the clinical setting of acute PE. The stepwise approach should make it possible to diagnose acute PE in critically ill patients using fast MR sequences and included the option to add comprehensive sequences when patients were stable. Forty-five patients with acute PE (26 men, 19 women; 41 ± 16 years) were included in this prospective study. The diagnosis was initially confirmed by MDCT as gold standard. MRI at 1.5 T was subsequently performed without any delay in medical treatment. The MRI protocol proceeded stepwise from robust to detailed imaging techniques (i.e., from TrueFISP and single shot HASTE sequence to MR perfusion and 3D-MR angiography) if the patient was able to tolerate additional imaging time. Diagnostic accuracy was evaluated on the central (lobar) and peripheral (segmental) levels. The complete MR protocol was applied in 40 of the 45 patients (88 %). In the remaining five patients with severe dyspnea the diagnosis of acute PE was established by using fast TrueFISP sequences that were insensitive to respiratory movement. All five patients suffered from a major central PE. Highest sensitivity was achieved by MR perfusion (lobar, 98 %; segmental, 95 %). Real-time TrueFISP and MR angiography showed the highest specificity (lobar, 90–100 %; segmental, 95–97 %). The combination of all MR sequences matched closely the results of MDCT (lobar: sensitivity 98 %, specificity 100 %; segmental: sensitivity 95 %, specificity 97 %). MRI using a stepwise protocol is a promising approach for diagnosing acute PE. The protocol can be tailored for dyspneic patients with central PE using real-time MRI sequences. The diagnostic accuracy for peripheral PE can be improved by using combined MR techniques, achieving comparable results to MDCT.

Introduction: Invasive coronary angiography is the reference method for identification of in-stent restenosis (ISR) bearing the disadvantages of high costs and invasiveness. New approaches like dual-source CT (DSCT) and 256-multi-slice CT (256-MSCT) may potentially be the future methods of choice to reliably exclude ISR in patients with low or intermediate risk of restenosis.We sought to compare the performance of DSCT and 256-MSCT for the in vitro assessment of stent lumen diameter and basic scan parameters in stents of various diameters and designs.Materials and Methods: In 16 coronary artery stents we evaluated relative in-stent lumen diameter, attenuation, noise, attenuation-/signal-to-noise ratio (ANR/SNR) and radiation dose (CTDIvol) in an acknowledged coronary vessel in vitro phantom (iodine-filled plastic tubes) with DSCT (Siemens, SOMATOM Definition, collimation = 2 x 64 x 0.6 mm, pitch = 0.26, current = 400 mAs/rot, voltage = 120 kV, tube-rotation-time = 330 ms) and 256-MSCT (Philips Brilliance, iCT, tube collimation = 2 x 128 x 0.625 mm, pitch = 0.18, current = 800 mAs(eff), voltage = 120 kV, tube-rotation-time = 270 ms). Diameter analysis was conducted with the observer-independent full-width-at-half-maximum (FWHM) technique.Results: DSCT and 256-MSCT revealed similar stent lumen diameters (50.7 +/- 7.2% vs. 50.8 +/- 7.4%, p = 0.98). Attenuation (-19 +/- 25 HU vs. 54 +/- 29 HU), ANR (-0.9 +/- 1.2 vs. 2.9 +/- 1.8) and SNR (12.1 +/- 2.4 vs. 17.4 +/- 1.9) were better in the DSCT (all p < 0.001) at the expense of significantly higher radiation doses (CTDIvol = 87 vs. 51 mGy, p < 0.01). Noise was comparable (21 +/- 2 HU vs. 20 +/- 2 HU, p = n.s.). Only stents with a diameter >3 mm allowed sufficient stent lumen assessment in both scanners and showed a relative lumen diameter of 60-66%.Conclusions: The measured stent lumen diameter and image noise were similar in both scanners. Yet the DSCT offered a more truthful stent lumen visualization at the cost of higher radiation dose.Applying the FWHM approach only stents with a diameter >3 mm offered sufficient stent lumen assessment. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

Purpose To investigate various anatomical locations of portomesenteric venous gas detected by computed tomography (CT) and their relationship with the underlying etiology and the outcome. Methods The study group consisted of 47 cases with evidence of portomesenteric venous gas detected on abdominal CT examinations, 12 cases were identified through a retrospective PACS search, 35 were prospectively included. The presence of gas at specific anatomical locations in the portomesenteric venous vasculature was assessed according to a pre-defined classification: the arcade vessels close to the bowel segments followed by segmental vessels, the superior mesenteric vein, the extra- and intrahepatic portal vein. The etiology of portomesenteric venous gas and its prognosis were assessed by review of surgical reports, histopathology and medical records. Surgery was performed on 30 patients. Results Overall 68.1% of cases were of ischemic etiology. Gas present in the arcade vessels was the best indicator for ischemia (sensitivity 93.8%; specificity 70.0%, positive predictive value 90.9%, negative predictive value 77.8%) compared to other locations and the mere presence of portomesenteric gas independent from the location. The overall mortality rate was 53.2%. Only gas in the arcade and segmental vessels were associated with considerably higher mortality rates (65.8% and 75.0%, respectively) and acceptable frequency (occurrence in 80.9% and 59.6%, respectively). Conclusions The study results indicate that the presence of gas at specific anatomical locations in the portomesenteric venous system, namely the arcade and segmental vessels, may serve as strong indicator for ischemic etiology and poor prognosis in the assessment of individual cases.