Reliability and validity of two methods of three-dimensional cervical volume measurement

Systematic analysis of measurement variability in lung cancer with multidetector computed tomography

OBJECTIVE:

To systematically analyze the nature of measurement variability in lung cancer with multidetector computed tomography (CT) scans.

METHODS:

Multidetector CT scans of 67 lung cancer patients were analyzed. Unidimensional (Response Evaluation Criteria in Solid Tumor criteria), bidimensional (World Health Organization criteria), and volumetric measurements were performed independently by ten radiologists and were repeated after at least 5 months. Repeatability and reproducibility measurement variations were estimated by analyzing reliability, agreement, variation coefficient, and misclassification statistically. The relationship of measurement variability with various sources was also analyzed.

RESULTS:

Analyses of 69 lung tumors with an average size of 1.1–12.1 cm (mean 4.3 cm) indicated that volumetric technique had the minimum measurement variability compared to the unidimensional or bidimensional technique. Tumor characteristics (object effect) could be the primary factor to influence measurement variability while the effect of raters (subjective effect) was faint. Segmentation and size in tumor characteristics were associated with measurement variability, and some mathematical function was established between the volumetric variability and tumor size.

CONCLUSION:

Volumetric technique has the minimum variability in measuring lung cancer, and measurement variability is associated with tumor size by nonlinear mathematical function.

Cervical length vs VOCAL cervical volume for predicting pre-term delivery in asymptomatic women at 20-22 weeks' pregnancy

We conducted a prospective observational study of 306 asymptomatic women at 20-22 weeks of pregnancy to compare 3-dimensional ultrasound measurements of cervical volume with 2-dimensional ultrasound measurements of cervical length to evaluate the performance of cervical volume as a predictor of pre-term delivery, compared with the current standard, cervical length. Participants underwent transvaginal ultrasound measurements of cervical length (mm) and cervical volume (cm(3)). Cervical volume as measured by 3-dimensional ultrasound was found to be a useful tool for predicting pre-term delivery; however, due to the high correlation between cervical length and cervical volume and the lack of differences in the sensitivity, specificity, positive predictive value, negative predictive value and relative risk between the two methods, replacing cervical length measurements with cervical volume calculations does not seem to be justified for this purpose, because of increased difficulty in volume acquisition.

Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix

OBJECTIVE

To assess the diagnostic performance of transabdominal sonographic measurement of cervical length in identifying patients with a short cervix.

METHODS

Cervical length was measured in 220 pregnant women using transabdominal and transvaginal ultrasound (US). Reproducibility and agreement between and within both methods were assessed. The diagnostic accuracy of transabdominal US for identifying cases with a cervical length <25 mm was evaluated.

RESULTS

Twenty-one out of 220 cases (9.5%) had a cervical length <25 mm by transvaginal US. Only 43% (n = 9) of patients with a short cervix were correctly identified by transabdominal US. In patients with a cervical length of <25 mm by transvaginal US, transabdominal measurement of the cervix overestimated this parameter by an average of 8 mm (95% LOAs, -26.4 to 10.5 mm). Among women without a short cervix, transabdominal US underestimated cervical length on average (LOA) by 1.1 mm (95% LOAs, -11.0 to 13.2 mm). Transvaginal US was also more reproducible (intraclass correlation coefficient: (ICC) (0.96; 95% CI, 0.94 to 0.97) based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal US (ICC: 0.71; 95% CI, 0.57 to 0.84). Transvaginal US detected 13 cases with funneling and six cases with sludge whereas only three cases of funneling and one of sludge were detected by transabdominal US.

CONCLUSION

Transabdominal measurement overestimated cervical LOA by 8 mm among women with a short cervix and resulted in the underdiagnosis of 57% of cases.