Gorka Bastarrika

CT Signs of Right Ventricular Dysfunction: Prognostic Role in Acute Pulmonary Embolism

OBJECTIVES The purpose of this study was to compare the prognostic role of various computed tomography (CT) signs of right ventricular (RV) dysfunction, including 3-dimensional ventricular volume measurements, to predict adverse outcomes in patients with acute pulmonary embolism (PE). BACKGROUND Three-dimensional ventricular volume measurements based on chest CT have become feasible for routine clinical application; however, their prognostic role in patients with acute PE has not been assessed. METHODS We evaluated 260 patients with acute PE for the following CT signs of RV dysfunction obtained on routine chest CT: abnormal position of the interventricular septum, inferior vena cava contrast reflux, right ventricle diameter (RVD) to left ventricle diameter (LVD) ratio on axial sections and 4-chamber (4-CH) views, and 3-dimensional right ventricle volume (RVV) to left ventricle volume (LVV) ratio. Comorbidities and fatal and nonfatal adverse outcomes according to the MAPPET-3 (Management Strategies and Prognosis in Pulmonary Embolism Trial-3) criteria within 30 days were recorded. RESULTS Fifty-seven patients (21.9%) had adverse outcomes, including 20 patients (7.7%) who died within 30 days. An RVD(axial)/LVD(axial) ratio >1.0 was not predictive for adverse outcomes. On multivariate analysis (adjusting for comorbidities), abnormal position of the interventricular septum (hazard ratio [HR]: 2.07; p = 0.007), inferior vena cava contrast reflux (HR: 2.57; p = 0.001), RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 2.51; p = 0.009), and RVV/LVV ratio >1.2 (HR: 4.04; p < 0.001) were predictive of adverse outcomes, whereas RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 3.68; p = 0.039) and RVV/LVV ratio >1.2 (HR: 6.49; p = 0.005) were predictive of 30-day death. CONCLUSIONS Three-dimensional ventricular volume measurement on chest CT is a predictor of early death in patients with acute PE, independent of clinical risk factors and comorbidities. Abnormal position of the interventricular septum, inferior vena cava contrast reflux, and RVD(4-CH)/LVD(4-CH) ratio are predictive of adverse outcomes, whereas RVD(axial)/LVD(axial) ratio >1.0 is not.

Comparison of Dual-Energy Computed Tomography of the Heart With Single Photon Emission Computed Tomography for Assessment of Coronary Artery Stenosis and of the Myocardial Blood Supply

To evaluate the performance of dual-energy computed tomography (CT) for integrative imaging of the coronary artery morphology and the myocardial blood supply, 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by a single-contrast medium-enhanced, retrospectively electrocardiographic-gated dual-energy CT (DECT) scan with simultaneous acquisition of high and low x-ray spectra. Thirteen patients subsequently underwent invasive coronary angiography (ICA). The DECT data were used to reconstruct anatomic coronary CT angiographic images and to map the myocardial iodine distribution within the left ventricular myocardium. Two independent observers analyzed all DECT studies for stenosis and myocardial iodine defects. A segmental comparison was performed between the stress/rest SPECT perfusion defects and DECT iodine defects and between the ICA and coronary CT angiographic findings for stenosis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were estimated, along with the kappa statistics. Overall, DECT had 92% sensitivity and 93% specificity, with 93% accuracy for detecting any type of myocardial perfusion defect seen on SPECT. Contrast defects at DECT correctly identified 85 (96%) of 89 fixed and 60 (88%) of 68 reversible myocardial perfusion defects. The interobserver agreement was very good (weighted kappa = 0.87). Compared with ICA, coronary CT angiography had 90% sensitivity, 94% specificity, and 93% accuracy for the detection of >50% stenosis. In conclusion, our initial experience suggests that DECT, as a single examination, might be promising for the integrative analysis of the coronary artery morphology and the myocardial blood supply and is in good agreement with ICA and SPECT.

Adenosine-stress dynamic myocardial CT perfusion imaging: initial clinical experience.

Objective:To evaluate the feasibility of adenosine-stress dynamic myocardial volume perfusion imaging with second generation dual source computed tomography (CT) for the qualitative and quantitative assessment of myocardial blood flow (MBF) compared with stress perfusion and viability magnetic resonance imaging (MRI). Material and Methods:Ten patients (8 male, 2 female, mean age 62.7 ± 7.1 years) underwent stress/rest perfusion and delayed-enhancement MRI, and a cardiac CT protocol comprising prospectively electrocardiogram -triggered coronary CT angiography, dynamic adenosine-stress myocardial perfusion imaging using a “shuttle” mode, and delayed enhancement acquisitions. Two independent observers visually assessed myocardial perfusion defects. For semi-quantitative evaluation, CT- and MRI-derived myocardial-to-left ventricular upslope indices were compared. Additionally, absolute MBF was quantified based on dynamic perfusion CT and correlated with semi quantitative CT measurements. Myocardial perfusion analysis was performed on a segmental basis. Analysis used paired t tests, Wilcoxon signed-rank test, linear correlation, and Bland-Altman statistics. Results:A total of 149 segments (93.1%) were suitable for analysis. Sensitivity, specificity, positive and negative predictive values for detection of myocardial perfusion defects at CT compared with MRI were 86.1%, 98.2%, 93.9%, and 95.7%, respectively. Semiquantitative analysis of CT data showed significant differences between ischemic and nonischemic myocardium with a signal intensity upslope that was comparable with MRI-derived values (CT: 5.2 ± 2 SI/s, MRI: 4.8 ± 2.3 SI/s, P > 0.05). Moderate correlation was observed between absolute CT quantification of MBF and semi-quantitative CT measurements. Mean total dose length product for the entire cardiac CT protocol was 1290.4 ± 233.3 mGy cm. Conclusion:Adenosine-stress volumetric first pass CT perfusion imaging is feasible and may enable the evaluation of qualitative and semi quantitative parameters of myocardial perfusion in a comparable fashion as MRI.

State of the Art: Iterative CT Reconstruction Techniques

Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limitations in CT imaging.

Diagnostic Yield of Electromagnetic Navigation Bronchoscopy Is Highly Dependent on the Presence of a Bronchus Sign on CT Imaging: Results From a Prospective Study

BACKGROUND Electromagnetic navigation bronchoscopy (ENB) has been developed as a novel ancillary tool for the bronchoscopic diagnosis of pulmonary nodules. Despite successful navigation in 90% of patients, ENB diagnostic yield does not generally exceed 70%. We sought to determine whether the presence of a bronchus sign on CT imaging conditions diagnostic yield of ENB and might account for the discrepancy between successful navigation and diagnostic yield. METHODS We conducted a prospective, single-center study of ENB in 51 consecutive patients with pulmonary nodules. ENB was chosen as the least invasive diagnostic technique in patients with a high surgical risk, suspected metastatic disease, or advanced-stage disease, or in those who demanded a preoperative diagnosis prior to undergoing curative resection. We studied patient and technical variables that might condition diagnostic yield, including size, cause, location, distance to the pleural surface, and fluorodeoxyglucose uptake of a given nodule; the presence of a bronchus sign on CT imaging; registration point divergence; and the minimum distance from the tip of the locatable guide to the nodule measured during the procedure. RESULTS The diagnostic yield of ENB was 67% (34/51). The sensitivity and specificity of ENB for malignancy in this study were 71% and 100%, respectively. ENB was diagnostic in 79% (30/38) patients with a bronchus sign on CT imaging but only in 4/13 (31%) with no discernible bronchus sign. Univariate analysis identified the bronchus sign (P = .005) and nodule size (P = .04) as statistically significant variables conditioning yield, but on multivariate analysis, only the bronchus sign remained significant (OR, 7.6; 95% CI, 1.8-31.7). No procedure-related complications were observed. CONCLUSIONS ENB diagnostic yield is highly dependent on the presence of a bronchus sign on CT imaging.

Dual-energy CT of the heart—Principles and protocols

The introduction of coronary CT angiography (cCTA) has reinvigorated the debate whether management of patients with suspected coronary artery disease (CAD) should be primarily based on physiological versus anatomical testing. Anatomical testing (i.e., cCTA or invasive catheterization) enables direct visualization and grading of coronary artery stenoses but has shortcomings for gauging the hemodynamic significance of lesions for myocardial perfusion. Conversely, rest/stress myocardial perfusion imaging (MPI) has been extensively validated for assessing the clinical significance of CAD by demonstrating fixed or reversible perfusion defects but has only limited anatomical information. There is early evidence that contrast medium enhanced dual-energy cCTA (DECT) has potential for the comprehensive analysis of coronary artery morphology as well as changes in myocardial perfusion. DECT exploits the fact that tissues in the human body and iodine-based contrast media have unique absorption characteristics when penetrated with different X-ray energy levels, which enables mapping the iodine (and thus blood) distribution within the myocardium. The purpose of this communication is to describe the practical application of this emerging technology for the comprehensive diagnosis of coronary artery disease in the context of the currently used tomographic imaging modalities (cCTA, nuclear MPI, MR MPI).

Original ResearchInterventional PulmonologyDiagnostic Yield of Electromagnetic Navigation Bronchoscopy Is Highly Dependent on the Presence of a Bronchus Sign on CT Imaging: Results From a Prospective Study

BACKGROUND Electromagnetic navigation bronchoscopy (ENB) has been developed as a novel ancillary tool for the bronchoscopic diagnosis of pulmonary nodules. Despite successful navigation in 90% of patients, ENB diagnostic yield does not generally exceed 70%. We sought to determine whether the presence of a bronchus sign on CT imaging conditions diagnostic yield of ENB and might account for the discrepancy between successful navigation and diagnostic yield. METHODS We conducted a prospective, single-center study of ENB in 51 consecutive patients with pulmonary nodules. ENB was chosen as the least invasive diagnostic technique in patients with a high surgical risk, suspected metastatic disease, or advanced-stage disease, or in those who demanded a preoperative diagnosis prior to undergoing curative resection. We studied patient and technical variables that might condition diagnostic yield, including size, cause, location, distance to the pleural surface, and fluorodeoxyglucose uptake of a given nodule; the presence of a bronchus sign on CT imaging; registration point divergence; and the minimum distance from the tip of the locatable guide to the nodule measured during the procedure. RESULTS The diagnostic yield of ENB was 67% (34/51). The sensitivity and specificity of ENB for malignancy in this study were 71% and 100%, respectively. ENB was diagnostic in 79% (30/38) patients with a bronchus sign on CT imaging but only in 4/13 (31%) with no discernible bronchus sign. Univariate analysis identified the bronchus sign (P = .005) and nodule size (P = .04) as statistically significant variables conditioning yield, but on multivariate analysis, only the bronchus sign remained significant (OR, 7.6; 95% CI, 1.8-31.7). No procedure-related complications were observed. CONCLUSIONS ENB diagnostic yield is highly dependent on the presence of a bronchus sign on CT imaging.

Transjugular Intrahepatic Portosystemic Shunt (TIPS) in the Treatment of Venous Symptomatic Chronic Portal Thrombosis in Non-cirrhotic Patients

AbstractPurpose: To present a series of cases of non-cirrhotic patients with symptomatic massive portal thrombosis treated by percutaneous techniques. All patients underwent a TIPS procedure in order to maintain the patency of the portal vein by facilitating the outflow. Methods: A total of six patients were treated for thrombosis of the main portal vein (6/6); the main right and left branches (3/6) and the splenic vein (5/6) and superior mesenteric vein (6/6). Two patients had a pancreatic malignancy; one patient with an orthotopic liver transplant had been surgically treated for a pancreatic carcinoma. Two patients had idiopathic thrombocytosis, and in the remaining patient no cause for the portal thrombosis was identified. During the initial procedure in each patient one or more approaches were tried: transhepatic (5/6), transileocolic (1/6), trans-splenic (1/6) or transjugular (1/6). In all cases the procedure was completed with a TIPS with either ultrasound guidance (3/6), “gun-shot” technique (2/6) or fluoroscopic guidance (1/6). Results: No complications were observed during the procedures. One patient had a repeat episode of variceal bleeding at 30 months, one patient remained asymptomatic and was lost to follow-up at 24 months, two patients were successfully treated surgically (cephalic duodenopancreatectomy) and are alive at 4 and 36 months. One patient remains asymptomatic (without new episodes of abdominal pain) at 16 months of follow-up. One patient died because of tumor progession at 10 months. Conclusion: Percutaneous techniques for portal recanalization are an interesting alternative even in non-acute thrombosis. Once flow has been restored in the portal vein TIPS may be necessary to obtain an adequate outflow, hence facilitating and maintaining the portal flow.

Assessment of left atrial volumes and function in orthotopic heart transplant recipients by dual-source CT: comparison with MRI.

Introduction:To compare left atrial performance with dual-source CT (DSCT) with respect to magnetic resonance imaging (MRI) in orthotopic heart transplant recipients. Methods:Twenty-nine consecutive heart transplant recipients (27 male; mean age 64.1 ± 13 years; mean time from transplantation 122.8 ± 69.7 months) referred for exclusion of cardiac allograft vasculopathy underwent cardiac DSCT and MRI. Standard biatrial technique was employed in 13 subjects whereas 16 were transplanted after the bicaval technique. Axial 5-mm slice-thickness DSCT datasets reconstructed in 5% steps of the cardiac cycle and axial 5-mm SSFP-MRI images were analyzed. Two blinded readers manually traced left atrial contours in random order to estimate end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). Parameters were compared with a paired sample Student t test. Concordance correlation coefficient (CCC) was calculated to determine measurement agreement between techniques and observers. Results:Left atrial volumes were significantly higher with cardiac DSCT (EDV: 170.9 ± 78.1 mL; ESV: 139.5 ± 76.6 mL) than with MRI (EDV: 158.2 ± 72.5 mL; ESV: 124.2 ± 68.2 mL), whereas left atrial EF was lower with DSCT (EF: 20.8% ± 7.5% vs. 23.6% ± 7.7%) (P < 0.05). Measurement agreement between DSCT and MRI was excellent for all parameters (CCC ≥0.82). Individuals operated with the biatrial anastomosis technique presented significantly higher left atrial volumes and lower EF compared with subjects with bicaval anastomosis. Interobserver agreement was excellent for all parameters (CCC ≥0.80). Conclusion:Even if DSCT slightly overestimates left atrial volumes with respect to MRI, results remain clinically valid. Bicaval surgical technique offers improved left atrial performance compared with standard biatrial anastomosis. DSCT may be used as a reliable tool to estimate left atrial parameters in orthotopic heart transplant recipients.

Quantification of left and right ventricular function and myocardial mass: comparison of low-radiation dose 2nd generation dual-source CT and cardiac MRI.

OBJECTIVE To prospectively evaluate the accuracy of left and right ventricular function and myocardial mass measurements based on a dual-step, low radiation dose protocol with prospectively ECG-triggered 2nd generation dual-source CT (DSCT), using cardiac MRI (cMRI) as the reference standard. MATERIALS AND METHODS Twenty patients underwent 1.5T cMRI and prospectively ECG-triggered dual-step pulsing cardiac DSCT. This image acquisition mode performs low-radiation (20% tube current) imaging over the majority of the cardiac cycle and applies full radiation only during a single adjustable phase. Full-radiation-phase images were used to assess cardiac morphology, while low-radiation-phase images were used to measure left and right ventricular function and mass. Quantitative CT measurements based on contiguous multiphase short-axis reconstructions from the axial CT data were compared with short-axis SSFP cardiac cine MRI. Contours were manually traced around the ventricular borders for calculation of left and right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction and myocardial mass for both modalities. Statistical methods included independent t-tests, the Mann-Whitney U test, Pearson correlation statistics, and Bland-Altman analysis. RESULTS All CT measurements of left and right ventricular function and mass correlated well with those from cMRI: for left/right end-diastolic volume r=0.885/0.801, left/right end-systolic volume r=0.947/0.879, left/right stroke volume r=0.620/0.697, left/right ejection fraction r=0.869/0.751, and left/right myocardial mass r=0.959/0.702. Mean radiation dose was 6.2±1.8mSv. CONCLUSIONS Prospectively ECG-triggered, dual-step pulsing cardiac DSCT accurately quantifies left and right ventricular function and myocardial mass in comparison with cMRI with substantially lower radiation exposure than reported for traditional retrospective ECG-gating.