Low Iodine Contrast Injection for CT Acquisition Prior to Transcatheter Aortic Valve Replacement: Aorta Assessment and Screening for Coronary Artery Disease.

RATIONALE AND OBJECTIVES: To assess both the complete aorta and coronary artery disease (CAD) using low iodine contrast computed-tomography angiography before transcatheter aortic valve replacement. MATERIALS AND METHODS: 84 patients underwent computed-tomography angiography before transcatheter aortic valve replacement: 42 with standard iodine injection protocol (P1:120 mL); 42 with a low dose iodine injection protocol (P2:60 mL). Mean attenuation and subjective image quality were rated at different levels of the aorta, iliac and coronary arteries. Sensitivity, specificity, negative and positive predictive values for depiction of CAD were calculated according to the coronary angiography. RESULTS: Mean attenuation was significantly higher in P1 for the ascending aorta (p < 0.001). No significant difference was observed regarding image quality of the aortic valve (p = 0.876), the ascending aorta (p = 0.306), or the abdominal aorta (p = 1.0). Diagnostic image quality of coronary arteries was excellent for P1 and P2 (94.6% vs 96.5%, p = 0.08). Sensitivity, specificity, negative and positive predictive values, and accuracy for depiction of CAD were excellent for P1 and P2 (100% vs 100%; 79% vs 86%, 70% vs 87%, 100% vs 100% and 86% vs 93%) without significant differences (p = 0.93; p = 0.58; p = 0.90; p = 1.0; p = 0.74), respectively. CONCLUSION: Despite a difference in aortic mean attenuation, a reduced iodine injection protocol showed similar image quality and detection of CAD in comparison with a standard injection protocol.

Impact of iterative reconstructions on objective and subjective emphysema assessment with computed tomography: a prospective study.

OBJECTIVES: To prospectively evaluate the impact of iterative reconstruction (IR) algorithms on pulmonary emphysema assessment as compared to filtered back projection (FBP). METHODS: One hundred ten unenhanced chest CT examinations were obtained on two different scanners. Image reconstructions from a single acquisition were done with different levels of IR and compared with FBP on the basis of the emphysema index (EI), lung volume and voxel densities. Objective emphysema assessment was performed with 3D software provided by each manufacturer. Subjective assessment of emphysema was performed as a blinded evaluation. Quantitative and subjective values were compared using repeated ANOVA analysis, Bland-Altman analysis and Kendall's coefficient of concordance (W). RESULTS: Lung volumes are stable on both units, throughout all IR levels (P ≥ 0.057). EI significantly decreases on both units with the use of any level of IR (P < 0.001). The highest levels of IR are responsible for a decrease of 33-36 % of EI. Significant differences in minimal lung density are found between the different algorithms (P < 0.003). Intra- and inter-reader concordance for emphysema characterisation is generally good (W ≥ 0.77 and W ≥ 0.86, respectively). CONCLUSIONS: Both commercially available IR algorithms used in this study significantly changed EI but did not alter visual assessment compared to standard FBP reconstruction at identical radiation exposure. KEY POINTS: • Objective quantification of pulmonary emphysema is sensitive to iterative reconstructions • Subjective evaluation of pulmonary emphysema is not influenced by iterative reconstructions • Consistency in reconstruction algorithms is of paramount importance for pulmonary emphysema monitoring.

ECG-triggered high-pitch CT for simultaneous assessment of the aorta and coronary arteries.

OBJECTIVES: To study the image quality of ECG-gated-computed tomography (CT) acquisition with a high-pitch CT imaging for the exploration of both the aorta and coronary arteries. METHODS: Eighty-four patients underwent high-pitch ECG-gated aortic CT without ß-blockers with iterative reconstruction algorithms. Contrast-to-noise ratio (CNR) between vessels and adjacent perivascular fat tissue were calculated on the aorta and the coronary arteries. Dose-length-products (DLP) were recorded. Two blinded readers graded image quality of the aorta and the coronary arteries on a 3-point scale. Coronary artery stenoses were compared with coronary angiograms in 24 patients. Kappa values were calculated. RESULTS: High-pitch acquisition resulted in a mean DLP of 234 ± 93 mGy cm(4.2 mSv) for an acquisition of the entire aorta, (mean 73 ± 16 bpm). CNR for ascending aorta was 10.6 ± 4 and CNR for coronary arteries was 9.85 ± 4.1. Image quality was excellent in 79/84 patients (94%), and excellent or moderate but diagnostic in 1087/1127 coronary artery segments (96%). 74 significant stenoses were observed, and 38/40 significant stenoses were confirmed by coronary angiography (K = 0.91, Sensitivity = 0.97, Specificity = 0.98). CONCLUSION: High-pitch ECG-gated aortic CT with iterative reconstructions allows an accurate exploration of both aorta and coronary arteries during the same acquisition, with limited dose deposition, despite the lack of ß-blockers and relatively high heart rate. Radiologists need to be aware of the necessity to analyze and report coronary artery disease in aortic examination.

[Electromagnetic navigation bronchoscopy for the assessment of peripheral lung nodules]. / Rencontre du "GPS" et du poumon: navigation electromagnétique pour le diagnostic des lésions pulmonaires.

Among recent technological progress, electromagnetic navigational bronchoscopy (ENB), based on the principle of "GPS", allows the bronchoscopist to reach parenchymal lesions situated beyond the field of regular bronchoscopy. Compared to CT-scan guided transthoracic needle aspiration, the yield is lower (65%). However, the rate of complication (pneumothorax, hemorrhage) is significantly lower and the patient is not irradiated. Moreover, the yield remains stable also for cases associated to a lower yield of the transthoracic approach (small and/or deep and/or benign lesion). Beyond the diagnosis of peripheral lung nodules, ENB (alone or in combination with endobronchial ultrasound) is also an efficient and safe tool for disease staging by simultaneous (during the same procedure) sampling of associated hypermetabolic lymph nodes.

Assessment of intra-articular volume of the wrist: a comparative study between CT-arthrography and dissection.

The aim of this study was to compare the intra-articular volumes of the wrist's joint measured by CT-arthrography and by dissection on ten cadavers. A good correlation was found between CT-arthrography and dissection in the assessment of the intra-articular volume of both wrist joints. A volume of 1.34 (+/-0.46) milliliter and 0.97 (+/-0.32) milliliter were found by Ct-arthrography for the radiocarpal and midcarpal joints, respectively. Dissection of the same wrists gives a volume of 1.24 (+/-0.33) and 0.90 (+/-0.21) for the radiocarpal and midcarpal joints, respectively. The knowledge of normal wrist-joint volume is a major prerequisite to evaluate carpal instability without ligaments' tears. We believe that CT-arthrography could be helpful in evaluating patients with suspected carpal instability.