This study aimed to demonstrate feasibility of statistical shape analysis techniques to identify distinguishing features of right ventricle (RV) shape as related to hemodynamic variables and outcome data in pulmonary hypertension (PH).Cardiovascular magnetic resonance images were acquired from 50 patients (33 PH, 17 Non-PH). Contemporaneous right heart catheterization data was collected for all individuals. Outcome was defined by all-cause mortality and hospitalization for heart failure. RV endocardial borders were manually segmented, and 3D surfaces reconstructed at end-diastole and end-systole. Registration and harmonic mapping were then used to create a quantitative correspondence between all RV surfaces. Proper orthogonal decomposition was performed to generate modes describing RV shape features. The first 15 modes captured over 98 % of the total modal energy. Two shape modes, 8 (free wall expansion) and 13 (septal flattening), stood out as relating to PH state (Mode 13: r=0.424, p=0.002. Mode 8: r=0.429, p=0.002). Mode 13 was significantly correlated with outcome (r = 0.438, p = 0.001), more so than any hemodynamic variable. Shape analysis techniques can derive unique RV shape descriptors corresponding to specific, anatomically meaningful features. The modes quantify shape features that had been previously only qualitatively related to PH progression. Modes describing relevant RV features are shown to correlate with clinical measures of RV status, as well as outcomes. These new shape descriptors lay the groundwork for a non-invasive strategy for identification of failing RVs, beyond what is currently available to clinicians.
Premise of the Research: Distyly is a floral polymorphism involving reciprocal herkogamy shaped by selection for pollen transfer efficiency. The variation of the floral organs involved in pollen transfer can be individually affected by environmental and genetic sources of variance, but the organ development will be canalised to minimize reciprocal inaccuracy between anthers and stigmas as this is the focus of selection.Methodology: We measured floral organ and cell length of both morphs of distylous Linum tenue (Linaceae) at different developmental stages of field-and glasshouse-grown plants. We analysed the results to measure reciprocal inaccuracy and identify sources of variance.Pivotal results: Flowers from the field were larger than those from the glasshouse due to both environmental and genetic (population) factors. Pistil and stamen length in adult flowers correlated with flower size, but reciprocal herkogamy was mostly invariant to the size individual floral organs. The length of short floral organs showed greater maladaptive bias, while the length of tall organs showed greater imprecision. During development, the pistils of pin flowers grew at a faster rate than in thrum flowers mostly due to cell elongation, while cell division was more important for male organ height.Conclusions: Distyly in L. tenue involves the interaction of multiple coordinated developmental and environmental mechanisms leading to limited but predictable patterns of variance in the expression of reciprocal herkogamy.
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