Consideration of Normal Variation of Perfusion Measurements in the Quantitative Analysis of Myocardial Perfusion SPECT: Usefulness in Assessment of Viable Myocardium / 핵의학분자영상

PURPOSE: Although automatic quantification software of myocardial perfusion SPECT provides highly objective and reproducible quantitative measurements, there is still some limitation in the direct use of quantitative measurements. In this study we derived parameters using normal variation of perfusion measurements, and tried to test the usefulness of these parameters. Materials and METHODS: In order to calculate normal variation of perfusion measurements on myocardial perfusion SPECT, 55 patients (M:F=28:27) of low-likelihood for coronary artery disease were enrolled and (201)Tl rest / (99m)Tc-MIBI stress SPECT studies were performed. Using 20-segment model, mean (m) and standard deviation (SD) of perfusion were calculated in each segment. As a myocardial viability assessment group, another 48 patients with known coronary artery disease, who underwent coronary artery bypass graft surgery (CABG) were enrolled. (201)Tl rest / (99m)Tc-MIBI stress / (201)Tl 24-hr delayed SPECT was performed before CABG and SPECT was followed up 3 months after CABG. From the preoperative 24-hr delayed SPECT, Q(delay) (perfusion measurement), delta(delay) (Q(delay)-m) and Z(delay) ((Q(delay)-m)/SD) were defined and diagnostic performances of them for myocardial viability were evaluated using area under curve (AUC) on receiver operating characteristic (ROC) curve analysis. RESULTS: Segmental perfusion measurements showed considerable normal variations among segments. In men, the lowest segmental perfusion measurement was 51.8+/-6.5 and the highest segmental perfusion was 87.0+/-5.9, and they are 58.7+/-8.1 and 87.3+/-6.0, respectively in women. In the viability assessment, Q(delay) showed AUC of 0.633, while those for delta(delay) and Z(delay) were 0.735 and 0.716, respectively. The AUCs of delta(delay) and Z(delay) were significantly higher than that of Q(delay) (p=0.001 and 0.018, respectively). The diagnostic performance of delta(delay), which showed highest AUC, was 85% of sensitivity and 53% of specificity at the optimal cutoff of -24.7. CONCLUSION: On automatic quantification of myocardial perfusion SPECT, the normal variation of perfusion measurements were considerable among segments. In the viability assessment, the parameters considering normal variation showed better diagnostic performance than the direct perfusion measurement. This study suggests that consideration of normal variation is important in the analysis of measurements on quantitative myocardial perfusion SPECT.

Clinical crown angulation and inclination of normal occlusion in a large Korean sample / 대한치과교정학회지

Angulation and inclination of clinical crown is important for diagnosing, treatment planning and developing convenient orthodontic attachments. The aim of the study was to establish normative data with higher reliability on the angulation and inclination of clinical crown of Koreans with normal occlusion. This study employed the dental casts of 307 (male, 187; female, 120) adult normal occlusion samples. The angulation and inclination of clinical crown were measured by set-up model checker. In order to ensure reliability, intra- and inter-rater error were evaluated 3 times. The resultant data obtained had excellent reliability, however, when compared with the previous data as well as with gender difference, clinically significant interpretation was impossible because the whithin-dataset normal variation was high, which was common pattern of angulation and inclination measuring data of previous research. The result of this biometric study seemed to suggest more substantive design of the multivariate, high-dimensional interpretation methodology of these normal variation is required if more compatible orthodontic appliance could be developed.