Impact of Hybrid Iterative Reconstruction on Agatston Coronary Artery Calcium Scores in Comparison to Filtered Back Projection in Native Cardiac CT

PURPOSE To investigate whether the effects of hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) measurements using the Agatston score lead to changes in assignment of patients to cardiovascular risk groups compared to filtered back projection (FBP). MATERIALS AND METHODS 68 patients (mean age 61.5 years; 48 male; 20 female) underwent prospectively ECG-gated, non-enhanced, cardiac 256-MSCT for coronary calcium scoring. Scanning parameters were as follows: Tube voltage, 120 kV; Mean tube current time-product 63.67 mAs (50 - 150 mAs); collimation, 2 × 128 × 0.625 mm. Images were reconstructed with FBP and with HIR at all levels (L1 to L7). Two independent readers measured Agatston scores of all reconstructions and assigned patients to cardiovascular risk groups. Scores of HIR and FBP reconstructions were correlated (Spearman). Interobserver agreement and variability was assessed with ĸ-statistics and Bland-Altmann-Plots. RESULTS Agatston scores of HIR reconstructions were closely correlated with FBP reconstructions (L1, R = 0.9996; L2, R = 0.9995; L3, R = 0.9991; L4, R = 0.986; L5, R = 0.9986; L6, R = 0.9987; and L7, R = 0.9986). In comparison to FBP, HIR led to reduced Agatston scores between 97 % (L1) and 87.4 % (L7) of the FBP values. Using HIR iterations L1 - L3, all patients were assigned to identical risk groups as after FPB reconstruction. In 5.4 % of patients the risk group after HIR with the maximum iteration level was different from the group after FBP reconstruction. CONCLUSION There was an excellent correlation of Agatston scores after HIR and FBP with identical risk group assignment at levels 1 - 3 for all patients. Hence it appears that the application of HIR in routine calcium scoring does not entail any disadvantages. Thus, future studies are needed to demonstrate whether HIR is a reliable method for reducing radiation dose in coronary calcium scoring

Einfluss der iterativen Rekonstruktionstechnik der vierten Generation auf die Bildqualität in der Niedrigdosis-Computertomographie des Thorax immunkomprimierter Patienten

PURPOSE To determine the image quality of an iterative reconstruction (IR) technique in low-dose MDCT (LDCT) of the chest of immunocompromised patients in an intraindividual comparison to filtered back projection (FBP) and to evaluate the dose reduction capability. MATERIALS AND METHODS 30 chest LDCT scans were performed in immunocompromised patients (Brilliance iCT; 20-40 mAs; mean CTDIvol: 1.7 mGy). The raw data were reconstructed using FBP and the IR technique (iDose4™, Philips, Best, The Netherlands) set to seven iteration levels. 30 routine-dose MDCT (RDCT) reconstructed with FBP served as controls (mean exposure: 116 mAs; mean CDTIvol: 7.6 mGy). Three blinded radiologists scored subjective image quality and lesion conspicuity. Quantitative parameters including CT attenuation and objective image noise (OIN) were determined. RESULTS In LDCT high iDose4™ levels lead to a significant decrease in OIN (FBP vs. iDose7: subscapular muscle 139.4 vs. 40.6 HU). The high iDose4™ levels provided significant improvements in image quality and artifact and noise reduction compared to LDCT FBP images. The conspicuity of subtle lesions was limited in LDCT FBP images. It significantly improved with high iDose4™ levels (> iDose4). LDCT with iDose4™ level 6 was determined to be of equivalent image quality as RDCT with FBP. CONCLUSION iDose4™ substantially improves image quality and lesion conspicuity and reduces noise in low-dose chest CT. Compared to RDCT, high iDose4™ levels provide equivalent image quality in LDCT, hence suggesting a potential dose reduction of almost 80%.Ziel: Beurteilung des Einflusses der iterativen Rekonstruktion (IR) auf die Bildqualität in der Niedrigdosis-Computertomographie (LDCT) des Thorax immunkomprimierter Patienten anhand eines intraindividuellen Vergleichs zur gefilterten Rückprojektion (FBP) sowie Begutachtung des Dosisreduktionsvermögens. Material und Methoden: 30 LDCTs wurden bei immunkomprimierten Patienten durchgeführt (Brilliance iCT: 20 – 40 mAs; mittlere CTDIvol: 1,7 mGy). Die Rohdaten wurden mittels FBP und IR (iDose4™, Philips, Best, Niederlande) mit 7 Iterationsstufen rekonstruiert. 30 mit FBP rekonstruierte Standarddosis-Computertomographien (RDCT) dienten als Kontrollgruppe (mittlere mAs:116; mittlere CDTIvol: 7,6 mGy). Drei verblindete Radiologen führten eine Begutachtung der subjektiven Bildqualität und Abgrenzbarkeit pathologischer Befunde durch. Als quantitative Parameter wurden die mittlere Dichte und das Bildrauschen (OIN) ermittelt. Ergebnisse: In der LDCT führten hohe iDose4™-Stufen zu einer signifikanten Reduktion des OIN (FBP vs. iDose7: M. subscapularis 139.4 vs. 40.6 HE). Trotz niedriger Strahlendosis ermöglichten hohe iDose4™-Stufen signifikante Verbesserungen der Bildqualität und der Artefakt- und Rauschreduktion. Die Abgrenzbarkeit von subtilen Läsionen wurde in LDCT FBP Bildern als eingeschränkt bewertet. Dies verbesserte sich signifikant mit Einsatz höherer iDose4™-Stufen (> iDose4). Der LDCT mit iDose6 wurde eine der RDCT mit FBP gleichwertige Bildqualität zugesprochen. Schlussfolgerungen: iDose4™ verbessert die Bildqualität und Abgrenzbarkeit pathologischer Befunde erheblich und führt gleichzeitig zur Rauschreduktion in der LDCT des Thorax. Verglichen mit der RDCT kann durch hohe iDose4™-Stufen trotz niedriger Strahlendosis in der LDCT eine gleichwertige Bildqualität erreicht werden, dies verspricht im Umkehrschluss eine potentielle Dosisreduktion von bis zu 80 %

Chest X-ray in right heart disease

© Springer International Publishing AG, part of Springer Nature 2018. Right heart pathology receives less attention from clinicians than left-sided heart disease, and knowledge of the importance of right heart, in particular right ventricle in disease development lags behind that of the left ventricle. In recent years, increasing evidence shows that right heart disease has significant impact on morbidity and mortality, thus highlighting the importance of recognizing right heart disease in clinical practice. Although ultrasound and computed tomography are the most commonly used diagnostic image techniques in the diagnosis of right heart disease, chest radiography still remains the first line technique in many applications. Despite non-specific findings in most of the situations, chest X-ray provides useful information for further diagnostic imaging tests of assessing right heart disease. This chapter provides an overview of applications of chest X-ray in the diagnosis of various right heart diseases