Quantitative detection of outlet strut separations in Björk-Shiley convexo-concave mitral valves
K A Powell1, N A Obuchowski, K D Mueller
1Department of Biomedical Engineering, Cleveland Clinic Foundation, OH 44195, USA. powell@bme.ri.ccf.org
Insights
A new objective postprocessing technique evaluates Björk-Shiley convexo-concave heart valve strut integrity. This method aids in identifying valves at risk of fracture, improving patient safety and diagnostic accuracy for outlet strut fractures.
Area of Science:
- Biomedical Engineering
- Cardiovascular Imaging
- Materials Science
Background:
- Björk-Shiley convexo-concave (BSCC) heart valves have a history of catastrophic outlet strut fractures (OSFs).
- Approximately two-thirds of reported OSFs resulted in patient mortality.
- Single-leg separation (SLS) precedes complete OSF, indicating a critical failure point.
Purpose of the Study:
- To develop an objective postprocessing technique for evaluating BSCC heart valve outlet strut integrity.
- To quantitatively assess strut leg integrity using cineradiographic images.
- To identify BSCC heart valves at risk of complete OSF.
Main Methods:
- Acquired cineangiographic images from 22 individuals (12 intact, 10 SLS valves).
- Verified valve status ex vivo.
- Evaluated quantitative measures of SLS, including decrease in pixel intensity (DIPI) ratio and gap half-width.
Main Results:
- Developed an objective postprocessing technique for evaluating outlet strut integrity.
- DIPI ratio and gap half-width were identified as diagnostic metrics for SLS.
- The model based on DIPI ratio achieved an area under the receiver operating characteristic curve of 0.892.
Conclusions:
- An objective postprocessing technique for evaluating BSCC heart valve strut integrity in cineradiographic images has been developed.
- The technique provides objective and quantitative assessment of strut integrity.
- The objective review demonstrated sensitivity comparable to subjective expert review at high specificity.
Background:
As of January 31, 1995, 564 outlet strut fractures (OSFs) of Björk-Shiley convexo-concave (BSCC) heart valves had been reported to the Shiley Heart Valve Research Center, of which approximately two thirds resulted in the death of the patient. Previous studies indicate that one leg of the outlet strut separates (single-leg separation, SLS) from the valve before the second leg breaks, which results in complete OSF. To identify those valves at risk of complete OSF, an in vivo radiographic imaging technique is being developed to evaluate the strut leg integrity. The goal of the present study was to develop an objective postprocessing technique to evaluate outlet strut leg integrity quantitatively in these cineradiographic images.
Methods And Results:
Twenty-two sets (12 intact valves, 10 SLS valves) of cineangiographic images were obtained from individuals whose valve status was subsequently verified ex vivo. Several quantitative measures of SLS were evaluated to identify possible loss of metal or gaps in the SLS legs. Two of these measures, decrease in pixel intensity (DIPI) ratio and gap half-width, are diagnostic metrics of SLS: i.e., the maximum likelihood estimate of the area under the receiver operating characteristic curve was 0.892 (SD, 0.066) for a model based on DIPI ratio and 0.802 (SD, 0.093) for gap half-width.
Conclusions:
We have developed a postprocessing technique that can be used to objectively evaluate outlet strut integrity in cineradiographic images of BSCC heart valves. At an estimated specificity of 1.0, the estimated sensitivity of the objective review was comparable to that of a subjective expert review panel.
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