Reply: To PMID 22173854

Evaluation of Cervical Elastography Strain Pattern to Predict Preterm Birth

PURPOSE

 To evaluate cervical elastography strain pattern as a predictive marker for spontaneous preterm delivery (SPTD).

MATERIALS AND METHODS

 In this case-control study cervical length (CL) and elastographic data (strain ratio, elastography index, strain pattern score) were acquired from 335 pregnant women (20th - 34th week of gestation) by transvaginal ultrasound. Data of 50 preterm deliveries were compared with 285 normal controls. Strain ratio and elastography index were calculated by placing two regions of interest (ROIs) in parallel on the anterior cervical lip. The strain ratio was determined by dividing the higher strain value by the lower one. The elastography index was defined as the maximum of the strain ratio curve. Elastographic images were assigned a new established strain pattern (SP) score between 0 and 2 according to the distribution of strain induced by compression.

RESULTS

 Elastography index, SP score and CL differed between preterm and normal pregnancies (1.61 vs. 1.27, p < 0.001; SP score value of "2": n = 31 (62 %) vs. n = 36 (12.6 %), p < 0.001; CL 30.7 vs. 41.0 mm, p < 0.001; respectively). The elastography index and SP score were associated with a higher predictive potential than CL measurement alone (AUC 0.8059 (area under the curve); AUC 0.7716; AUC 0.7631; respectively). A combination of all parameters proved more predictive than any single parameter (AUC 0.8987; respectively).

CONCLUSION

 Higher elastography index and SP scores were correlated with an elevated risk of SPTD and are superior to CL measurement as a predictive marker. A combination of these parameters could be used as a "Cervical Index" for the prediction of SPTD.

Elastography Improves the Diagnostic Accuracy of Sonography in Differentiating Endometrial Polyps and Submucosal Fibroids

OBJECTIVES

To assess whether strain elastography may be used to visualize the different stiffness of endometrial polyps and submucosal fibroids.

METHODS

We conducted a prospective monocentric single-operator study on diagnostic accuracy. Patients who qualified for hysteroscopy because of suspected endometrial polyps and submucosal fibroids were included. Before the procedure, all patients underwent routine sonographic and power Doppler examinations. Additionally, the stiffness of intrauterine lesions was assessed by strain elastography. The enhancement was adjusted to visualize hard myometrium and soft endometrium around the intrauterine lesion. Due to their histologic structure, we assumed that on strain elastography, endometrial polyps should appear as soft lesions, whereas submucosal fibroids should appear as hard lesions. Sonographic, power Doppler, and elastographic findings were verified by pathologic examinations after hysteroscopies. The diagnostic accuracy of sonography, power Doppler imaging, and strain elastography was compared by the McNemar test.

RESULTS

Forty-seven patients were included and underwent hysteroscopy. In 29 cases, endometrial polyps were found, and in 18, submucosal fibroids were found. The diagnostic accuracy rates for B-mode sonography, power Doppler imaging, and strain elastography in distinguishing endometrial polyps and submucosal fibroids were 70.2%, 65.9%, and 89.4%, respectively. The proportion of correct findings was significantly higher for strain elastography than for B-mode sonography (P = .0265) and power Doppler imaging (P = .0153).

CONCLUSIONS

Strain elastography complements sonography in differentiating intrauterine lesions. Strain elastography may be used to visualize the different stiffness of endometrial polyps and submucosal fibroids.

Quantitative elastography of the uterine cervix as a predictor of preterm delivery

OBJECTIVE

To evaluate the correlation between preterm delivery before 37 weeks of gestation and ultrasound elastography strain measurement of cervical stiffness.

STUDY DESIGN

In this prospective study, 182 pregnant women were examined vaginally by ultrasound elastography from a mid-sagittal plane. Cervical length was measured and strain was calculated in four regions of interest on the anterior cervical lip. First, the software was validated by intraobserver variability. Second, strain and strain ratios were calculated with adjusted software presets and correlated to the outcome of spontaneous preterm delivery (sPTD).

RESULT

A total of 8928 regions of interest (ROIs) and 6696 ratios were evaluated. The median gestational age at examination was 26 ± 6.1 weeks. A median maternal age of 33 ± 5.6 and a medial parity of 1 ± 0.9 were observed. Intra-Class-Correlation values in validation phase ranged from 0.893 to 0.967. The prevalence of sPTD was 11.9%. Strain ratio Rselective was identified as the best predictor of preterm delivery. Rselective values >0.89 were associated with preterm delivery with a sensitivity of 0.59 and a specificity of 0.86 (odds ratio=1.474 for an increase of 0.1 in Rselective; P=0.002).

CONCLUSION

Ultrasound elastography strain measurement of cervical stiffness is correlated with the predictability of preterm delivery.

Elastography in predicting preterm delivery in asymptomatic, low-risk women: a prospective observational study

Background

Despite the efforts to decrease the rate of preterm birth, preterm delivery is still the main cause of neonatal morbidity and mortality. Identifying patients threatened with preterm delivery remains one of the main obstetric challenges. The aim of this study was to estimate the potential value of elastographic evaluation of internal cervical os stiffness at 18-22 weeks of pregnancy in low risk, asymptomatic women in the prediction of spontaneous preterm delivery.

Methods

This prospective observational study included 333 low-risk, asymptomatic women presenting for the routine second trimester ultrasound scan according to the Polish Gynecological Society recommendation between 18-22 weeks of pregnancy. Ultrasound examinations of the cervix were performed transvaginally. The following data were recorded: elastographic color assessment of the internal os and ultrasound cervical length at 18-22 and 30 weeks of pregnancy; maternal age; obstetrical history; presence of cervical funneling at 30 weeks of pregnancy; gestational age at birth. Elastographic assessment of the internal os was performed using a color map: red (soft), yellow (medium soft), blue (medium hard) and purple (hard). If two colors were visible in the region of the internal os, the softer option was noted. Statistical analysis was performed using Statistica software (version 10, Statsoft Poland) using the following tests: chi square test to compare frequency of preterm deliveries in various categories of internal os assessment and Spearman correlation test to determine the correlation between elastographic assessment and cervical shortening. To determine the cut off category of internal os elastography assessment in selecting high preterm delivery risk patients we have calculated the sensivity, specifity, negative predictive value and positive predictive value.

Results

The number of preterm deliveries (<37 weeks of pregnancy) was significantly higher in the red and yellow groups, than in the blue and purple groups. The sensivity, specifity, NPV and PPV for both red and yellow internal os assessment in predicting preterm delivery were 85.7%, 97.6%, 98.3% and 81.1% respectively.

Conclusions

Elastographic assessment of the internal cervical os at 18-22 weeks of pregnancy may identify patients with high risk of preterm delivery in low-risk, asymptomatic women.

Quantitative elastography for cervical stiffness assessment during pregnancy

AIM

Feasibility and reliability of tissue Doppler imaging-(TDI-) based elastography for cervical quantitative stiffness assessment during all three trimesters of pregnancy were evaluated.

MATERIALS AND METHODS

Prospective case-control study including seventy-four patients collected between the 12th and 42nd weeks of gestation. The tissue strain (TS) was measured by two independent operators as natural strain. Intra- and interoperator intraclass correlation coefficient (ICC) agreements were evaluated.

RESULTS

TS measurement was always feasible and exhibited a high performance in terms of reliability (intraoperator ICC-agreement=0.93; interoperator ICC agreement=0.89 and 0.93 for a single measurement and for the average of two measurements, resp.). Cervical TS showed also a significant correlation with gestational age, cervical length, and parity.

CONCLUSIONS

TS measurement during pregnancy demonstrated high feasibility and reliability. Furthermore, TS significantly correlated with gestational age, cervical length, and parity.