Showing papers by "Zhong Chen published in 2012"

Infarct segmentation challenge on delayed enhancement MRI of the left ventricle

Abstract: This paper presents collated results from the Delayed Enhancement MRI (DE-MRI) segmentation challenge at MICCAI 2012. DE-MRI Images from fifteen patients and fifteen pigs were randomly selected from two different imaging centres. Three independent sets of manual segmentations were obtained for each image and included in this study. A ground truth consensus segmentation based on all human rater segmentations was obtained using an Expectation-Maximization (EM) method (the STAPLE method). Automated segmentations from five groups contributed to this challenge.

Infarct myocardium tissue heterogeneity assessment using pre-contrast and post-contrast T1 maps acquired with Modified Look-Locker Inversion Recovery (MOLLI) imaging

Abstract: We aim to explore tissue heterogeneity assessment using T1 maps generated with the modified Look Locker (MOLLI) sequence in patients with previous myocardial infarct. Conclusion: Differences between healthy myocardium and scarred tissues can be reliably distinguished from the R1 values derived from pre-contrast T1 maps.Potentially, patients without scarred myocardium do not need post-contrast imaging. Inpatients with scarred tissues, ΔR1 value derived from both thepre- and the post-contrast T1 maps provides better distinction between grey zone and scar core than either pre-contrast or post-contrast R1 value alone.

Infarct segmentation of the left ventricle using graph-cuts

Abstract: Delayed-enhancement magnetic resonance imaging (DE-MRI) is an effective technique for imaging left ventricular (LV) infarct. Existing techniques for LV infarct segmentation are primarily threshold-based making them prone to high user variability. In this work, we propose a segmentation algorithm that can learn from training images and segment based on this training model. This is implemented as a Markov random field (MRF) based energy formulation solved using graph-cuts. A good agreement was found with the Full-Width-at-Half-Maximum (FWHM) technique.

001 Unbiased assessment of symptomatic “response rate” to cardiac resynchronisation therapy by systematic review of randomised controlled trials (REVERSE, MIRACLE, MIRACLE ICD, MIRACLE ICD II, CARE-HF, COMPANION, CONTAK-CD, and MUSTIC)

Abstract: Background Varied rates of individual symptomatic response are cited for cardiac resynchronisation therapy (CRT) but have never been systematically evaluated together. Nor has spontaneous recovery rate been routinely subtracted, to clearly identify rate of symptomatic response genuinely attributable to CRT. Method and Results First, we systematically reviewed the last 92 papers on PubMed about CRT. 74% referred to responder rates but only 18% recognised the existence of “response to doing nothing”. Second, we examined symptomatic response rates in the randomised CRT trials CARE-HF, COMPANION, CONTAK-CD, MIRACLE, MIRACLE-ICD, MIRACLE-ICD II, MUSTIC, and REVERSE, totalling 3904 patients. The weighted average symptomatic response rate, assessed using the clinical composite score was 54% for those randomised to CRT vs 40% for those randomised to no CRT. Using NYHA score, these values were 51% and 35% respectively. When symptomatic response rate was measured using 6-min walk distance and Minnesota Living with Heart Failure Quality of Life Score, a much larger spontaneous improvement was seen in the control arm of the blinded studies (device implanted but turned off in the control arm) compared to the open studies (no device implanted in the control arm). Spontaneous improvement was almost twice as high in the control arms of the blinded studies vs the open studies. With 6-min walk distances, 55% of the improvement in distance walked in the CRT arm was seen in the control arm for the blinded studies, vs 25% in the open. These values were 56% and 23% respectively with the Minnesota Living with Heart Failure Quality of Life Score. Conclusions Quoting CRT responder rates in isolation, without recognising spontaneous responders, is common but invalid. Response rate with CRT, at 54%, is not the response rate attributable to CRT, which is only 14% of implanted patients. Three-quarters of those who “responded” with CRT would have done so even without CRT. Subjective quantitative markers seem to show an additional placebo effect and the placebo effect is more pronounced in the blinded studies than open studies. CRT definitely prevents death and reduces symptoms, but commonly-quoted “responder rates” are exaggerated, and are dependent on the measure used, and the blinding methodology used in the trial referenced.

060 The practice and perception of transvenous lead extraction in the UK: lessons from a nationwide survey

Abstract: Introduction The rate of cardiac implantable electronic device (CIED) implantation in the UK has been rising consistently and this trend is likely to continue. We sought to establish the nature of lead extraction practice in the UK. Methods The Heart Rhythm UK (HRUK) directory of members was used to compile a list of potential respondents for the survey. A link to the Survey Monkey online tool was sent with HRUK administrative support and responses were collated prior to analysis. The survey consisted of 21 questions and all results were anonymous. Results In total, 29 responses were received and of these 24 (82.8%) regularly performed trasnvenous lead extractions. The vast majority (82.8%) were electrophysiologists. Most operators performed up to 25 procedures per year (Abstract 060 figure 1A). Most procedures were performed in the EP lab with on-site surgical cover present at all but one site. The nature of surgical cover was generally informal (Abstract 060 figure 1B). The perceived commonest reason for extraction was a combination of infection/erosion and sepsis (93.1%). After a failed attempt at manual traction the most widely used method of extraction was to use a mechanical dissection sheath (65.5%) followed by the use of a laser sheath (21.1%). Peri- and post-procedure temporary pacing mostly utilised either a standard temporary pacing wire or an externalised permanent pacemaker device. Active fixation endocardial pace/sense leads were generally perceived the easiest and safest leads to extract while dual coil defibrillator leads and active fixation coronary sinus leads were perceived the most difficult and associated with the greatest risk (Abstract 060 figure 2A,B). The perception of minor and major complication rates and the risk of death increased with device complexity. The risk of minor complications was perceived to be 4% or less by the majority of respondents across the device range. The same measure for major complications and death was 2% and 1% respectively. Conclusions and Implications Transvenous lead extraction is becoming increasingly common and most UK operators who responded to our survey perform 25 cases or fewer per annum. Surgical stand-by support was mostly informal but a significant minority of cases were performed in an operating theatre with a surgeon present. The perceived risk of the procedure was broadly in line with widely published figures internationally. The 2009 Heart Rhythm Society consensus document made a series of recommendations with regards to training, case volume and stand-by surgical support. It is suggested that a minimum of 20 cases per year be performed by each operator and that a cardiothoracic surgeon be physically on site and capable of performing an emergent procedure promptly. Accordingly, increased operator caseload and closer links between EP extractors and surgeons should be seen as achievable goals.