Real-time CMR-guided LV lead placement is feasible and achievable in a single clinical setting and may prove helpful to preferentially select sites for LV lead placement.

Human parechoviruses (HPeVs) are frequent pathogens with a seroprevalance of over 90 % in adults. Recent studies on these viruses have increased the number of HPeV types to eight. Here we analyse the complete genome of one clinical isolate, PicoBank/HPeV1/a, and VP1 and 3D protein sequences of PicoBank/HPeV6/a, isolated from the same individual 13 months later. PicoBank/HPeV1/a is closely related to other recent HPeV1 isolates but is distinct from the HPeV1 Harris prototype isolated 50 years ago. The availability of an increasing number of HPeV sequences has allowed a detailed analysis of these viruses. The results add weight to the observations that recombination plays a role in the generation of HPeV diversity. An important finding is the presence of unexpected conservation of codons utilized in part of the 3D-encoding region, some of which can be explained by the presence of a phylogenetically conserved predicted secondary structure domain. This suggests that in addition to the cis-acting replication element, RNA secondary structure domains in coding regions play a key role in picornavirus replication. INTRODUCTIONPicornaviruses are non-enveloped, positive-sense RNA viruses with icosahedral capsids, composed of 60 copies of three or four virus-encoded proteins (VP1-4 or VP0, VP1 and VP3) (Stanway et al., 2002(Stanway et al., , 2005. They have a genome of around 7000-8000 nt encoding one polyprotein which is cleaved by virus proteases to give the structural and non-structural (2A-C and 3A-D) proteins. Picornaviruses consist of economically and socially very important human and animal viruses such as polioviruses, other enteroviruses, rhinoviruses, hepatitis A virus, footand-mouth disease virus and parechoviruses. Currently, parechoviruses consist of two species: human parechovirus (HPeV) and Ljungan virus (LV) (Johansson et al., 2002;Joki-Korpela & Hyypiä, 2001;Stanway & Hyypiä, 1999;Stanway et al., 2000). HPeVs are frequent infectious agents and although they usually cause mild gastroenteritis and respiratory disease in young children, more serious cases, such as flaccid paralysis, encephalitis and myocarditis, have also been reported, particularly associated with HPeV3 infection (Baumgarte et al., 2008;Benschop et al., 2006a Benschop et al., , 2008bEhrnst & Eriksson, 1993;Figueroa et al., 1989;Harvala et al., 2008Harvala et al., , 2009Joki-Korpela & Hyypiä, 2001). Recently, HPeV1 has also been linked to otitis media (Tauriainen et al., 2008). With the isolation of several HPeV types in recent studies AlSunaidi et al., 2007;Baumgarte et al., 2008;Benschop et al., 2006b; Drexler et al., 2009;Ito et al., 2004;Li et al., 2009), eight types (1-8) of HPeVs are currently known.HPeVs have several distinctive features compared with other picornaviruses (Ghazi et al., 1998;Hyypiä et al., 1992;Stanway et al., 1994Stanway et al., , 2000. Post-translational cleavage of the polyprotein results in only three structural proteins (VP0, VP3 and VP1), as the cleavage of VP0 to VP4 and VP2 seen in other picornaviruses does n...

Purpose: Image‐guided cardiac interventions involve the use of fluoroscopic images to guide the insertion and movement of interventional devices. Cardiorespiratory gating can be useful for 3D reconstruction from multiple x‐ray views and for reducing misalignments between 3D anatomical models overlaid onto fluoroscopy. Methods: The authors propose a novel and potentially clinically useful retrospective cardiorespiratory gating technique. The principal component analysis (PCA) statistical method is used in combination with other image processing operations to make our proposed masked‐PCA technique suitable for cardiorespiratory gating. Unlike many previously proposed techniques, our technique is robust to varying image‐content, thus it does not require specific catheters or any other optically opaque structures to be visible. Therefore, it works without any knowledge of catheter geometry. The authors demonstrate the application of our technique for the purposes of retrospective cardiorespiratory gating of normal and very low dose x‐ray fluoroscopy images. Results: For normal dose x‐ray images, the algorithm was validated using 28 clinical electrophysiology x‐ray fluoroscopy sequences (2168 frames), from patients who underwent radiofrequency ablation (RFA) procedures for the treatment of atrial fibrillation and cardiac resynchronization therapy procedures for heart failure. The authors established end‐systole, end‐expiration, and end‐inspiration success rates of 97.0%, 97.9%, and 97.0%, respectively. For very low dose applications, the technique was tested on ten x‐ray sequences from the RFA procedures with added noise at signal to noise ratio (SNR) values of50, 10, 8, 6, 5, 2, and 1 to simulate the image quality of increasingly lower dose x‐ray images. Even at the low SNR value of 2, representing a dose reduction of more than 25 times, gating success rates of 89.1%, 88.8%, and 86.8% were established. Conclusions: The proposed technique can therefore extract useful information from interventional x‐ray images while minimizing exposure to ionizing radiation.

The motion and deformation of catheters that lie inside cardiac structures can provide valuable information about the motion of the heart. In this paper we describe the formation of a novel statistical model of the motion of a coronary sinus (CS) catheter based on principal component analysis of tracked electrode locations from standard mono-plane x-ray fluoroscopy images. We demonstrate the application of our model for the purposes of retrospective cardiac and respiratory gating of x-ray fluoroscopy images in normal dose x-ray fluoroscopy images, and demonstrate how a modification of the technique allows application to very low dose scenarios. We validated our method on ten mono-plane imaging sequences comprising a total of 610 frames from ten different patients undergoing radiofrequency ablation for the treatment of atrial fibrillation. For normal dose images we established systole, end-inspiration and end-expiration gating with success rates of 100%, 92.1% and 86.9%, respectively. For very low dose applications, the method was tested on the same ten mono-plane x-ray fluoroscopy sequences without noise and with added noise at signal to noise ratio (SNR) values of √50, √10, √8, √6, √5, √2 and √1 to simulate the image quality of increasingly lower dose x-ray images. The method was able to detect the CS catheter even in the lowest SNR images with median errors not exceeding 2.6 mm per electrode. Furthermore, gating success rates of 100%, 71.4% and 85.7% were achieved at the low SNR value of √2, representing a dose reduction of more than 25 times. Thus, the technique has the potential to extract useful information whilst substantially reducing the radiation exposure.