Michel Montaudon

Non-invasive assessment of liver fibrosis with impulse elastography: Comparison of Supersonic Shear Imaging with ARFI and FibroScan®

BACKGROUND & AIMS Non-invasive assessment of liver fibrosis by elastography is a rapidly developing field with frequent technological innovations. The aim of this study was to assess the diagnostic performances of Supersonic Shear Imaging (SSI) for the diagnosis of liver fibrosis in chronic liver disease. METHODS A total of 349 consecutive patients with chronic liver diseases who underwent liver biopsy from November 2011 to October 2013 were prospectively enrolled. For each patient, liver stiffness was assessed by SSI, ARFI, FibroScan® (M probe for patients with BMI <30 kg/m(2), and XL probe for patients with BMI ⩾30 kg/m(2)), performed within two weeks of liver biopsy. Areas under the receiver operating curves (AUROCs) were performed and compared for each degree of liver fibrosis. RESULTS SSI, FibroScan®, and ARFI correlated significantly with histological fibrosis score (r=0.79, p<0.00001; r=0.70, p<0.00001; r=0.64, p<0.00001, respectively). AUROCs of SSI, FibroScan®, and ARFI were 0.89, 0.86, and 0.84 for the diagnosis of mild fibrosis; 0.88, 0.84, and 0.81 for the diagnosis of significant fibrosis; 0.93, 0.87, and 0.89, for the diagnosis of severe fibrosis; 0.93, 0.90, and 0.90 for the diagnosis of cirrhosis, respectively. SSI had a higher accuracy than FibroScan® for the diagnosis of severe fibrosis (⩾F3) (p=0.0016), and a higher accuracy than ARFI for the diagnosis of significant fibrosis (⩾F2) (p=0.0003). No significant difference was observed for the diagnosis of mild fibrosis and cirrhosis. CONCLUSIONS SSI is an efficient method for the assessment of liver fibrosis in chronic liver diseases, comparing favourably to FibroScan® and ARFI.

Inverse Relationship Between Fractionated Electrograms and Atrial Fibrosis in Persistent Atrial Fibrillation: Combined Magnetic Resonance Imaging and High-Density Mapping

OBJECTIVES This study sought to evaluate the relationship between fibrosis imaged by delayed-enhancement (DE) magnetic resonance imaging (MRI) and atrial electrograms (Egms) in persistent atrial fibrillation (AF). BACKGROUND Atrial fractionated Egms are strongly related to slow anisotropic conduction. Their relationship to atrial fibrosis has not yet been investigated. METHODS Atrial high-resolution MRI of 18 patients with persistent AF (11 long-lasting persistent AF) was registered with mapping geometry (NavX electro-anatomical system (version 8.0, St. Jude Medical, St. Paul, Minnesota)). DE areas were categorized as dense or patchy, depending on their DE content. Left atrial Egms during AF were acquired using a high-density, 20-pole catheter (514 ± 77 sites/map). Fractionation, organization/regularity, local mean cycle length (CL), and voltage were analyzed with regard to DE. RESULTS Patients with long-lasting persistent versus persistent AF had larger left atrial (LA) surface area (134 ± 38 cm(2) vs. 98 ± 9 cm(2), p = 0.02), a higher amount of atrial DE (70 ± 16 cm(2) vs. 49 ± 10 cm(2), p = 0.01), more complex fractionated atrial Egm (CFAE) extent (54 ± 16 cm(2) vs. 28 ± 15 cm(2), p = 0.02), and a shorter baseline AF CL (147 ± 10 ms vs. 182 ± 14 ms, p = 0.01). Continuous CFAE (CFEmean [NavX algorithm that quantifies Egm fractionation] <80 ms) occupied 38 ± 19% of total LA surface area. Dense DE was detected at the left posterior left atrium. In contrast, the right posterior left atrium contained predominantly patchy DE. Most CFAE (48 ± 14%) occurred at non-DE LA sites, followed by 41 ± 12% CFAE at patchy DE and 11 ± 6% at dense DE regions (p = 0.005 and p = 0.008, respectively); 19 ± 6% CFAE sites occurred at border zones of dense DE. Egms were less fractionated, with longer CL and lower voltage at dense DE versus non-DE regions: CFEmean: 97 ms versus 76 ms, p < 0.0001; local CL: 153 ms versus 143 ms, p < 0.0001; mean voltage: 0.63 mV versus 0.86 mV, p < 0.0001. CONCLUSIONS Atrial fibrosis as defined by DE MRI is associated with slower and more organized electrical activity but with lower voltage than healthy atrial areas. Ninety percent of continuous CFAE sites occur at non-DE and patchy DE LA sites. These findings are important when choosing the ablation strategy in persistent AF.

Computed tomography-fluoroscopy overlay evaluation during catheter ablation of left atrial arrhythmia

AIMS Proper visualization of left atrial (LA) and pulmonary vein (PV) anatomy is of crucial importance during atrial fibrillation (AF) ablation. This two-centre study evaluated a new automatic computed tomography (CT)-fluoroscopy overlay system (EP navigator, Philips Medical Systems, Best, The Netherlands) and the accuracy of different registration methods. METHODS AND RESULTS Fifty-six consecutive patients (age: 56 +/- 14) with symptomatic AF underwent contrast CT of the LA/PV prior to ablation. Three registration methods were evaluated and validated by comparison with LA angiography: (i) catheter registration: the placement of catheters in identifiable anatomical structures; (ii) heart contour: based on aligning the fluoroscopy heart contours and the 3D-rendered CT volume; and (iii) spine registration: based on automatically aligning the segmented CT spine on fluoroscopy. Computed tomography segmentation was achieved in all but one patient due to motion artefacts. The mean duration of segmentation was 10 min and average registration lasted 7 min. Catheter and heart contour registration were highly accurate (discrepancy of 1.3 +/- 0.6 and 0.3 +/- 0.5 mm, respectively) when compared with spine registration (17 +/- 9 mm, P < 0.05). The EP navigator was helpful during trans-septal puncture, gave an internal view of the atria and allowed tracking of ablation lesions. CONCLUSION The EP navigator enabled accurate live integration of CT images and real-time fluoroscopy. Registration utilizing catheter placement or heart contours was stable and reliable.

Bronchial measurements in patients with asthma: comparison of quantitative thin-section CT findings with those in healthy subjects and correlation with pathologic findings.

PURPOSE To analyze and compare computed tomographic (CT) bronchial measurements in patients with asthma and healthy subjects and to correlate bronchial morphometric parameters with functional data and immunohistologic markers of airway remodeling and inflammation. MATERIALS AND METHODS This retrospective study was approved by the institutional review board; patient informed consent was not required. CT and pulmonary function tests were performed in 27 patients separated into two groups: 15 patients with asthma (three men; mean age, 43.1 years +/- 5.3 [standard error of mean]) and 12 healthy subjects (10 men; mean age, 45.0 years +/- 5.4). Endobronchial biopsies were performed in 11 subjects. Bronchial cross-sectional wall area (WA) and lumen area (LA) were measured by using validated software, and wall thickness (WT), total area (TA), WA/LA ratio, and WA/TA ratio were computed. Slope and maximal local slope of each parameter along bronchial generations were calculated. RESULTS Patients with asthma demonstrated significantly lower LA, TA, and WA and higher WA/LA and WA/TA ratios than healthy subjects downward from the fourth bronchial generation. Correlations existed between slope and maximal local slope of WA/LA and/or WA/TA ratios and functional data reflecting bronchial obstruction (r = 0.46-0.58, P = .001-.025), subepithelial membrane thickness (r = 0.67-0.69, P = .019-.023), smooth muscle layer area (r = 0.75, P = .007), subepithelial layer area (r = 0.81, P = .002), and infiltration of the bronchial wall by inflammatory cells (r = 0.67-0.86, P = .049-.003). CONCLUSION Axial reconstructions with orthogonal measurements along the airways enabled by three-dimensional segmentation methods are able to demonstrate significant changes in bronchial morphometry, predicting airflow limitation in asthma, and may have a role in the noninvasive measurement of airway remodeling.

Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event.

Dual-energy CT perfusion and angiography in chronic thromboembolic pulmonary hypertension: diagnostic accuracy and concordance with radionuclide scintigraphy

ObjectivesTo evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) perfusion and angiography versus ventilation/perfusion (V/Q) scintigraphy in chronic thromboembolic pulmonary hypertension (CTEPH), and to assess the per-segment concordance rate of DECT and scintigraphy.MethodsForty consecutive patients with proven pulmonary hypertension underwent V/Q scintigraphy and DECT perfusion and angiography. Each imaging technique was assessed for the location of segmental defects. Diagnosis of CTEPH was established when at least one segmental perfusion defect was detected by scintigraphy. Diagnostic accuracy of DECT perfusion and angiography was assessed and compared with scintigraphy. In CTEPH patients, the per-segment concordance between scintigraphy and DECT perfusion/angiography was calculated.ResultsFourteen patients were diagnosed with CTEPH and 26 with other aetiologies. DECT perfusion and angiography correctly identified all CTEPH patients with sensitivity/specificity values of 1/0.92 and 1/0.93, respectively. At a segmental level, DECT perfusion showed moderate agreement (κ = 0.44) with scintigraphy. Agreement between CT angiography and scintigraphy ranged from fair (κ = 0.31) to slight (κ = 0.09) depending on whether completely or partially occlusive patterns were considered, respectively.ConclusionsBoth DECT perfusion and angiography show satisfactory performance for the diagnosis of CTEPH. DECT perfusion is more accurate than angiography at identifying the segmental location of abnormalities.Key Points• Chronic thromboembolic pulmonary hypertension (CTEPH) is potentially treatable by surgery.• Dual-energy computed tomography (DECT) allows angiography and perfusion using a single acquisition.• Both DECT perfusion and angiography showed satisfactory diagnostic performance in CTEPH.• DECT perfusion was more accurate than angiography in identifying segmental abnormalities.

Assessment of bronchial wall thickness and lumen diameter in human adults using multi-detector computed tomography: comparison with theoretical models.

A thickened bronchial wall is the morphological substratum of most diseases of the airway. Theoretical and clinical models of bronchial morphometry have so far focused on bronchial lumen diameter, and bronchial length and angles, mainly assessed from bronchial casts. However, these models do not provide information on bronchial wall thickness. This paper reports in vivo values of cross‐sectional wall area, lumen area, wall thickness and lumen diameter in ten healthy subjects as assessed by multi‐detector computed tomography. A validated dedicated software package was used to measure these morphometric parameters up to the 14th bronchial generation, with respect to Weibels model of bronchial morphometry, and up to the 12th according to Boydens classification. Measured lumen diameters and homothety ratios were compared with theoretical values obtained from previously published studies, and no difference was found when considering dichotomic division of the bronchial tree. Mean wall area, lumen area, wall thickness and lumen diameter were then provided according to bronchial generation order, and mean homothety ratios were computed for wall area, lumen area and wall thickness as well as equations giving the mean value of each parameter for a given bronchial generation with respect to its value in generation 0 (trachea). Multi‐detector computed tomography measurements of bronchial morphometric parameters may help to improve our knowledge of bronchial anatomy in vivo, our understanding of the pathophysiology of bronchial diseases and the evaluation of pharmacological effects on the bronchial wall.

Age, atrial fibrillation, and structural heart disease are the main determinants of left atrial fibrosis detected by delayed-enhanced magnetic resonance imaging in a general cardiology population.

We studied the extent and distribution of left atrial (LA) fibrosis on delayed‐enhanced (DE) MRI in a general cardiology population.

Congenital coronary arteries anomalies: review of the literature and multidetector computed tomography (MDCT)-appearance

The prevalence of coronary arteries congenital anomalies is 1 to 2% in the general population. Although the spectrum of their clinical manifestations is very broad from total inocuity to lethal, anomalies of coronary arteries need to be recognized by clinicians in certain circumstances: they are the first cause of death in young adults under physical exercise and an abnormal course of a coronary artery can complicate a cardiac surgery. Therefore, a non-invasive test is highly suitable for detecting anomalies of coronary arteries and multidetector computed tomography (MDCT) is likely to be the best one. To understand how anomalies of coronary arteries may occur, we have reviewed the recent literature about their development. Then, the main types of anomalies are presented with their clinical context, and representative MDCT images from our personal database are used for illustration.

Feasibility of aortic pulse pressure and pressure wave velocity MRI measurement in young adults.

To investigate the feasibility of assessing, noninvasively, aortic pulse pressure (APP) and pulse wave velocity (PWV) in the ascending aorta of young adults by means of velocity‐encoded magnetic resonance (MR) imaging.