Ha. Vrooman et al., QUANTITATIVE ASSESSMENT OF THE PRESENCE OF A SINGLE LEG SEPARATION INBJORK-SHILEY CONVEXOCONCAVE PROSTHETIC HEART-VALVES, Investigative radiology, 32(9), 1997, pp. 540-549
RATIONALE AND OBJECTIVES. The authors developed an analytic software p
ackage for the objective and reproducible assessment of a single leg s
eparation (SLS) in the outlet strut of Bjork-Shiley convexoconcave (BS
CC) prosthetic heart valves. METHODS. The radiographic cinefilm record
ings of 18 phantom valves (12 intact and 6 SLS) and of 43 patient valv
es were acquired. After digitization of regions of interest in a cinef
rame, several processing steps were carried out to obtain a one-dimens
ional corrected and averaged density profile along the central axis of
each strut leg, To characterize the degree of possible separation, tw
o quantitative measures were introduced: the normalized pit depth (NPD
) and the depth-sigma ratio (DSR), The group of 43 patient studies was
divided into a learning set (25 patients) and a test set (18 patients
). RESULTS. All phantom valves with an SLS were detected (sensitivity,
100%) at a specificity of 100%, The threshold values for the NPD and
the DSR to decide whether a fracture was present or not were 3.6 and 2
.5, respectively, On the basis of the visual interpretations of the 25
patient studies (learning set) by an expert panel, it was concluded t
hat none of the patients had an SLS, To achieve a 100% specificity by
quantitative analysis, the threshold values for the NPD and the DSR we
re set at 5.8 and 2.5, respectively, for the patient data. Based on th
ese threshold values, the analysis of patient data from the test set r
esulted in one false-negative detection and three false-positive detec
tions. CONCLUSIONS. An analytic software package for the detection of
an SLS was developed, Phantom data showed excellent sensitivity (100%)
and specificity (100%), Further research and software development is
needed to increase the sensitivity and specificity for patient data.