Constrained 2-D/3-D Registration for Motion Compensation in AFib Ablation Procedures

Abstract. Fluoroscopic overlay images rendered from pre-operative vol-umetric data can provide additional guidance for physicians during catheter ablation procedures for treatment of atrial fibrillation (AFib). As these overlay images are compromised by cardiac and respiratory motion, mo-tion compensation methods have been proposed. The approaches so far either require simultaneous biplane imaging for 3-D motion compensa-tion or, in case of mono-plane X-ray imaging, provide only a limited 2-D functionality. To overcome the downsides of the previously suggested methods, we propose a new approach that facilitates full 3-D motion compensation even if only mono-plane X-ray views are available. To this end, we use constrained model-based 2-D/3-D registration to track a circumferential mapping catheter which is commonly used during AFib catheter ablation procedures. Our approach yields an average 2-D track-ing error of 0.6 mm and an average 3-D tracking error of 2.1 mm.

Rapid automatic segmentation of abnormal tissue in late gadolinium enhancement cardiovascular magnetic resonance images for improved management of long-standing persistent atrial fibrillation

Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In order for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to ameliorate the AF management, the ready availability of the accurate enhancement segmentation is required. However, the computer-aided segmentation of enhancement in LGE CMR of AF is still an open question. Additionally, the number of centres that have reported successful application of LGE CMR to guide clinical AF strategies remains low, while the debate on LGE CMR’s diagnostic ability for AF still holds. The aim of this study is to propose a method that reliably distinguishes enhanced (abnormal) from non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and 3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients studied at our centre. Methods: Enhancement segmentation was achieved by employing thresholds benchmarked against the statistics of the whole left atrial blood-pool (LABP). The test-set cross-validation mechanism was applied to determine the input feature representation and algorithm that best predict enhancement threshold levels. Results: Global normalized intensity threshold levels T PRE = 1 1/4 and T POST = 1 5/8 were found to segment enhancement in data-sets acquired pre-ablation and at 3 months post-ablation, respectively. The segmentation results were corroborated by using visual inspection of LGE CMR brightness levels and one endocardial bipolar voltage map. The measured extent of pre-ablation fibrosis fell within the normal range for the specific arrhythmia phenotype. 3D volume renderings of segmented post-ablation enhancement emulated the expected ablation lesion patterns. By comparing our technique with other related approaches that proposed different threshold levels (although they also relied on reference regions from within the LABP) for segmenting enhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels employed by other centres may not be usable for clinical studies performed in our centre. Conclusions: The proposed technique has great potential for successful employment in the AF management within our centre. It provides a highly desirable validation of the LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition protocol and image analysis strategy inevitably impede the selection of a universally optimal algorithm for segmentation of enhancement in AF studies

Novel Echocardiographic Biomarkers in the Management of Atrial Fibrillation

Purpose of Review: Atrial fibrillation (AF) is the most common arrhythmia in adults. The number of patients with AF is anticipated to increase annually, mainly due to the aging population alongside improved arrhythmia detection. AF is associated with a significantly elevated risk of hospitalization, stroke, thromboembolism, heart failure, and all-cause mortality. Echocardiography is one of the key components of routine assessment and management of AF. Therefore, the aim of this review is to briefly summarize current knowledge on “novel” echocardiographic parameters that may be of value in the management of AF patients. Recent Findings: Novel echocardiographic biomarkers and their clinical application related to the management of AF have been taken into consideration. Both standard parameters such as atrial size and volume but also novels like atrial strain and tissue Doppler techniques have been analyzed. Summary: A number of novel echocardiographic parameters have been proven to enable early detection of left atrial dysfunction along with increased diagnosis accuracy. This concerns particularly experienced echocardiographers. Hence, these techniques might improve the prediction of stroke and thromboembolic events among AF patients and need to be further developed and disseminated. Nonetheless, even the standard imaging parameters could be of significant value and should not be discontinued in everyday clinical practice. © 2019, The Author(s)

La influencia de ?rboles leguminosos y no leguminosos, sobre el forraje que crece bajo ellos

Tesis (M. Sc) --IICA, Turrialba (Costa Rica), 1967El presente trabajo se hizo como una parte de un experimento iniciado en 1959 en el Departamento de Zootecnia del Instituto Interamericano de Ciencias Agr?colas, en Turrialba, Costa Rica, con el fin de determinar si los ?rboles de los potreros influyen sobre la cantidad y calidad del forraje que crece bajo ellos. En 1959 se sembraron 180 ?rboles de cuatro especies diferentes: tres leguminosas, Por? Gigante (Erythrina poeppigiana), Sam?n (Pithecolobium saman), y Madera Negra (Gliricidia sepium), y una no leguimosas, Laurel (Cordia alliodora). Se agruparon en 5 parcelas por especie con 9 ?rboles cada una, distanciados a 13 metros unos de otros. Tambi?n se incluyeron cinco parcelas sin ?rboles. Debido a que a la ?poca de este trabajo muchos ?rboles ya no exist?an y otros se encontraban en mal estado se consideraron solamente cinco ?rboles de cada especie, seleccionando uno de cada parcela, adem?s de las cinco parcelas testigos. La selecci?n de cada ?rbol se hizo considerando su desarrollo, su situaci?n con respecto a los otros ?rboles y la presencia de pasto guinea (Panicum maximum). La poblaci?n herb?cea del potrero estaba formada principalmente por los pastos Guinea (P. maximum), Gamalote (Paspalum fasciculatum), Comino (Homolepis aturensis) y Pangola (Digitaria decumbens). Tambi?n exist?an especies de hoja ancha y ciper?ceas, aunque en menor cantidad. Para evaluar la influencia de los ?rboles se tomaron los siguientes datos: 1. Intercepci?n de luz de los ?rboles. 2. Cobertura de la vegetaci?n herb?cea. 3. Producci?n de materia seca de la capa herb?cea y a) su contenido de prote?na b) su contenido de fibra. 4. Nitr?geno total del suelo. 5. Observaci?n y muestreo de ra?ces. 6. Recolecci?n e identificaci?n de las principales especies herb?ceas. De los resultados de este trabajo se concluy?: 1. Los ?rboles leguminosos para proporcionar sombra al ganado en los potreros son beneficiosos porque aumentan el valor forrajero de los pastos que crecen bajo ellos, sin disminuir su cantidad. 2. El Laurel no afect? la calidad y cantidad del forraje, pero tampoco proporcion? suficiente sombra para el ganado. Considerando que el desarrollo de los ?rboles de Sam?n, Madera Negra y Laurel todav?a no hab?a llegado a su m?ximo, las conclusiones a que se llegan deber?n tomarse como parciales y no como definitivas

Comparison of growth of Holstein heifers fed 100% or 115% of NRC requirements

The 1989 Annual KSU Dairy Day is known as Dairy Day, 1989One hundred and one Holstein heifers from the KSU Dairy Unit were used in this experiment. They were assigned to two treatments in which they were fed either 100% or 115% of the 1988 NRC requirements of energy, protein, major minerals, and major vitamins. Body measurements (height, length, heart girth, weight, body condition scores, and backfat thickness) were recorded. Rations for each group were formulated using the average wt of the heifers. Results suggest that feeding 115% of NRC requirements produces larger frame heifers (without excess body condition), with potential for earlier calving, compared to feeding 100% of NRC requirements

Comparison of growth and production of holstein heifers raised on 100% or 115% of the NRC requirements

The 1990 Annual KSU Dairy Day is known as Dairy Day, 1990One hundred and ten Holstein heifers from the KSU Dairy Research Unit were used in this experiment. They were fed either 100% (control) or 115% (enhanced) of NRC requirements for energy, protein, major minerals, and vitamins from 6 mo of age to shortly before calving. Heifers in the enhanced group calved at an earlier age, had larger heart girths, and were heavier than controls. At this time, 46 of the heifers have completed at least 50 days in lactation. Based on their projected 305-2X-ME records, the heifers in the enhanced group have produced slightly, but not significantly, more milk and milk fat

Performance of holstein heifers reared on 100 or 115% of NRC requirements from 3 to 12 months of age and then switched to the opposite treatment

Holstein heifers from the Kansas State University Dairy Teaching and Research Unit were used from 3 mo of age until 21 d before estimated date of calving. They were fed either 100 (control, C) or 115% (enhanced, E) of the 1989 National Research Council (NRC) requirements for major nutrients from 3 to 12 mo of age, then, until 21 d before freshening, the treatments were switched from 100 to 115% NRC (CE) or from 115 to 100% NRC (EC). At puberty, heifers had similar body weights (613, E vs 617, C) but heifers fed E were 1 month younger (11 vs 12 mo). Heifers fed the E diet were heavier and had larger heart girth at 12 mo of age than the group fed C. After switching, the group fed CE increased more in body weight, body length, wither height, and body condition than the group fed EC