A Novel Approach for Semiautomated Three-Dimensional Quantification of Mitral Regurgitant Volume Reflects a More Physiologic Approach to Mitral Regurgitation.

BACKGROUND: Quantification of mitral regurgitation (MR) by echocardiography is integral to assessing lesion severity and entails the integration of multiple Doppler-based parameters. These methods are founded primarily upon the principle of proximal isovelocity surface area (PISA), a two-dimensional (2D) method known to involve several assumptions regarding MR jet characteristics. The authors analyzed the results of a semiautomated method of three-dimensional (3D)-based regurgitant volume (RVol) estimation that accounts for jet behavior throughout the cardiac cycle and compared it with conventional 2D PISA methods for MR quantification. METHODS: A total of 50 patients referred for transesophageal echocardiography for evaluation of primary (n = 25) and secondary (n = 25) MR were included for analysis. Three-dimensional full-volume color data sets were acquired, along with standard 2D methods for PISA calculation. A 3D semiautomated MR flow quantification algorithm was applied offline to calculate 3D RVol, with simultaneous temporal curves generated from the 3D data set. Three-dimensional RVol was compared with 2D RVol. Three-dimensional vena contracta area was also performed in all cases. RESULTS: There was a modest correlation between 2D RVol and 3D RVol (r = 0.60). The semiautomated 3D approach resulted in significantly lower values of RVol compared with 2D PISA. Real-time and dynamic flow curve patterns were used for integral estimates of 3D RVol over the cardiac cycle, with a distinct bimodal pattern in functional MR and a brief and solitary peak in primary MR. CONCLUSIONS: Using a semiautomated 3D software for the quantification of MR allows the simultaneous calculation of 3D RVol with an automated generation of dynamic flow curves characteristic of the underlying MR mechanism. The present flow curve pattern results highlight well-known differences between MR flow dynamics in degenerative MR compared with functional MR.

Validation of Semiautomated Quantification of Mitral Valve Regurgitation by Three-Dimensional Color Doppler Transesophageal Echocardiography.

BACKGROUND: The aim of this study was to evaluate the accuracy of mitral regurgitation (MR) volume quantified on three-dimensional (3D) color Doppler transesophageal echocardiography (TEE) using new semiautomated software compared with conventional two-dimensional (2D) proximal isovelocity surface area (PISA) transthoracic echocardiography (TTE) and TEE and cardiac magnetic resonance imaging (CMR). METHODS: Fifty-one patients (mean age, 63 ± 16 years; 35 men) prospectively underwent TTE, TEE, and CMR for MR evaluation. Regurgitant volume (RVol) by 3D MR flow quantification was compared with 2D TTE, TEE, and CMR, and the accuracy of evaluation of severe MR by 3D MR flow quantification was compared against guideline criteria by TEE. RESULTS: Twenty-nine patients had severe MR, 16 had moderate MR, and six had mild MR. Three-dimensional MR flow quantification was feasible in all patients, including prolapse (n = 37), restriction (n = 9), functional MR (n = 5), and eccentric or multiple jects (n = 41). RVol on 3D MR flow quantification correlated well with RVol on 2D PISA TTE (interclass correlation coefficient [ICC] = 0.75, P < .001), quantitatively estimated RVol (ICC = 0.74, P < .001), and 2D PISA TEE (ICC = 0.79, P < .001). Three-dimensional MR flow quantification agreed better with CMR (ICC = 0.86, P < .001) than did RVol on 2D PISA TTE (ICC = 0.66, P < .001) and 2D PISA TEE (ICC = 0.69, P < .001), with narrower limits of agreement on Bland-Altman analysis. Three-dimensional MR flow quantification had high accuracy for diagnosing severe MR using TEE (area under the curve = 0.85, 95% CI 0.74-0.96, P < .001) or CMR (area under the curve = 0.95; 95% CI, 0.89-1.00; P < .001) as the criterion. CONCLUSIONS: The new software enabled semiautomated 3D MR flow quantification in complex MR with multiple and eccentric jets and showed better agreement with CMR than 2D PISA TTE or TEE, suggesting that this method is more accurate than conventional 2D PISA TTE and TEE.

A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy.

BACKGROUND: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. METHODS: Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. RESULTS: Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. CONCLUSION: DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician.