Magnetic resonance diffusion tensor imaging of cervical microstructure in normal early and late pregnancy in vivo.

BACKGROUND: Cervical remodeling is an important aspect of birth timing. Before cervical ripening, the collagen fibers are arranged in a closely interweaved network, but during ripening, the fibers become disorganized and the cervix becomes more hydrated. To quantitatively measure cervical remodeling, we need a noninvasive method to monitor changes in cervical collagen fiber organization and hydration in vivo. OBJECTIVE: To use diffusion tensor imaging to image and quantify the spatial and temporal differences in cervical microstructure between normal early and late pregnancies. STUDY DESIGN: After institutional review board approval and consent, a group of healthy women in early pregnancy (22 patients at 12-14 weeks' gestation) and a group in late pregnancy (27 patients at 36-38 weeks' gestation) underwent magnetic resonance imaging on a Siemens MAGNETOM Vida 3 Tesla unit. Diffusion tensor imaging of the cervix in the axial plane was performed with a two-dimensional single-shot echo planar imaging diffusion-weighted sequence. In early and late pregnancy groups, the differences of the diffusion tensor imaging measures were compared between the subglandular zone and the outer stroma regions of the cervix. In addition, the diffusion tensor imaging measures were compared between the early and late pregnancy groups. Finally, for the late pregnancy group, the diffusion tensor imaging measures were compared between the primipara and multipara groups. RESULTS: Diffusion tensor imaging measures of microstructure significantly differed between the subglandular zone and outer stroma regions of the cervix in both early and late pregnancies. In the subglandular zone, fractional anisotropy was lower in the late pregnancy group than in the early pregnancy group (0.37 [0.34-0.42] vs 0.50 [0.43-0.58]; P<.0005), suggesting increased collagen fiber disorganization in this zone. In addition, mean diffusivity was higher in the late pregnancy group than in the early pregnancy group (1.84 [1.73-2.02] mm2/sec×10-3 vs 1.56 [1.42-1.69] mm2/sec×10-3; P=.001), suggesting increased hydration in the subglandular zone. In the outer stroma, neither fractional anisotropy (0.44 [0.40-0.50] vs 0.41 [0.37-0.43]; P=.095) nor mean diffusivity (2.09 [1.92-2.25] mm2/sec×10-3 vs 2.12 [2.04-2.24] mm2/sec×10-3; P=.269) significantly differed between early pregnancy and late pregnancy, suggesting insignificant temporal microstructural changes in this cervical zone. Diffusion tensor imaging measures did not significantly differ between cervixes from primiparous and multiparous women in late pregnancy. CONCLUSION: This in vivo study demonstrates that diffusion tensor imaging can noninvasively quantify the microstructural differences in collagen fiber organization and hydration in cervical subregions between early pregnancy and late pregnancy.

Prediction of Double-Lumen Tube Size By Ultrasonography for Asian Women: A Prospective Observational Study.

OBJECTIVE: To assess the agreement of the diameter of the cricoid cartilage by computed tomography and ultrasonography and to compare the accuracy of the left double-lumen tubes (DLTs) and right DLTs predicted by ultrasonography for Asian women. DESIGN: Prospective observational study. SETTING: Academic, tertiary care hospital. PARTICIPANTS: Fifty female patients intubated with a left DLT and 50 female patients intubated with a right DLT. INTERVENTIONS: No intervention. MEASUREMENTS AND MAIN RESULTS: A radiologist measured the transverse cricoid diameter by computed tomography (CT), and an independent echographer measured the transverse cricoid diameter using ultrasonography. The size of the DLT was selected based on the cricoid diameter by ultrasonography. The agreement of the transverse cricoid diameter was assessed by computed tomography and ultrasonography. The accuracy of the DLT, the tracheal segment, and the bronchial segment were compared between the left intubation group and right intubation group. There was a good agreement between the transverse cricoid diameter measured by ultrasonography and CT (r = 0.946, p < 0.001). The overall accuracy of the DLTs was similar between the groups (86.0% v 92.0%, p = 0.318). There were no significant differences in the accuracy of the tracheal segment (96.0% v 94.0%; p = 1.000) and the bronchial segment (90.0% v 98.0%, p = 0.056). CONCLUSIONS: The transverse diameter of the cricoid cartilage in most Asian women can be accurately measured by ultrasonography. The size of the DLT for Asian women can be predicted by ultrasonography measurement of the cricoid diameter.

The Incidence of Tracheal Bronchus in Thoracic Surgery Patients and Its Implication for Lung Isolation: A Retrospective Cohort Study.

OBJECTIVE: To investigate the incidence of tracheal bronchus (TB) and explore its implication for lung isolation. DESIGN: Retrospective cohort study. SETTING: Academic, tertiary care hospital. PARTICIPANTS: The study comprised 7,102 thoracic patients with- one lung ventilation. INTERVENTIONS: No intervention. MEASUREMENTS AND MAIN RESULTS: Two independent anesthesiologists reviewed the computed tomography images to identify the presence of a TB, and their results were confirmed by a radiologist. The clinical data of patients with a TB were obtained from the electronic medical record. Data regarding the device used to provide lung isolation, preoperative oxygen saturation (SpO2), and intraoperative SpO2 during one- lung ventilation were obtained from the electronic anesthesia record. The incidence of TB was 1.08% (77 of 7,102). The TB arose from the right side of the trachea in all 77 patients, including 70 type Ⅲ TBs and 7 type Ⅱ TBs. Left- and right-sided double-lumen tubes (DLTs) were used in 54 and 23 patients, respectively. For patients with a left-sided DLT, the median SpO2 and incidence of hypoxemia (SpO2 <90%) were 97% and 6 of 54 (11.1%), respectively. For patients with a right DLT, the median SpO2 and incidence of hypoxemia were 95% and 7 of 20 (35.0%), respectively. There were significant differences in the mean SpO2 and the incidence of hypoxemia between patients intubated with left- and right-sided DLTs (p = 0.014 and p = 0.016, respectively). CONCLUSIONS: Preoperative diagnosis of TB is important when lung isolation is needed. The left-sided DLT can be used for most patients with a TB.

The development of the cricoid cartilage and its implications for the use of endotracheal tubes in the pediatric population.

BACKGROUND: The rigid cricoid cartilage is functionally the narrowest portion of the larynx. There is some controversy over the shape of the pediatric cricoid cartilage in the transverse plane. It is important to understand the development of the cricoid cartilage so that endo-traceheal tubes can be used more safely. AIM: To determine changes in the internal diameter and shape of the cricoid cartilage during development and explore the implications of those changes for the selection of ETT type and size for children. METHODS: The cervical computed tomography scans were reviewed in patients aged 1-20 years. After performing the multiplanar reconstruction and correcting the slant, the transverse and anteroposterior internal diameters of the inlet and outlet of the cricoid cartilage were measured, respectively. The angle between the arch and the lamina of the cricoid cartilage in the middle sagittal plane was measured. The ratios of transverse to anteroposterior diameter for the inlet and outlet of the cricoid cartilage were calculated, respectively. RESULTS: In females, the internal diameters of the cricoid cartilage increased linearly with age. In males, the internal diameters of the cricoid cartilage exhibited a growth spurt during adolescence. The transverse diameter of the inlet was the smallest diameter of the cricoid cartilage, and the predicting formula of the transverse diameter of the inlet for children aged 1-12 was 0.4 × age (year) + 5.1, R2  = .758. The angle between the arch and lamina of the cricoid cartilage and the ratios of transverse to anteroposterior diameter correlated weakly with age. CONCLUSION: The transverse inner diameter of the inlet is the smallest diameter of the cricoid cartilage. The "funnel shape" of the cricoid cartilage remains unchanged during development. The outer diameter should be considered when selecting an endotracheal tube.

Diffusion tensor MR imaging characteristics of cerebral white matter development in fetal pigs.

BACKGROUND: The purpose of this study was to investigate the anisotropic features of fetal pig cerebral white matter (WM) development by magnetic resonance diffusion tensor imaging, and to evaluate the developmental status of cerebral WM in different anatomical sites at different times. METHODS: Fetal pigs were divided into three groups according to gestational age: E69 (n = 8), E85 (n = 11), and E114 (n = 6). All pigs were subjected to conventional magnetic resonance imaging (MRI) and diffusion tensor imaging using a GE Signa 3.0 T MRI system (GE Healthcare, Sunnyvale, CA, USA). Fractional anisotropy (FA) was measured in deep WM structures and peripheral WM regions. After the MRI scans,the animals were sacrificed and pathology sections were prepared for hematoxylin & eosin (HE) staining and luxol fast blue (LFB) staining. Data were statistically analyzed with SPSS version 16.0 (SPSS, Chicago, IL, USA). A P-value < 0.05 was considered statistically significant. Mean FA values for each subject region of interest (ROI), and deep and peripheral WM at different gestational ages were calculated, respectively, and were plotted against gestational age with linear correlation statistical analyses. The differences of data were analyzed with univariate ANOVA analyses. RESULTS: There were no significant differences in FAs between the right and left hemispheres. Differences were observed between peripheral WM and deep WM in fetal brains. A significant FA growth with increased gestational age was found when comparing E85 group and E114 group. There was no difference in the FA value of deep WM between the E69 group and E85 group. The HE staining and LFB staining of fetal cerebral WM showed that the development from the E69 group to the E85 group, and the E85 group to the E114 group corresponded with myelin gliosis and myelination, respectively. CONCLUSIONS: FA values can be used to quantify anisotropy of the different cerebral WM areas. FA values did not change significantly between 1/2 way and 3/4 of the way through gestation but was then increased dramatically at term, which could be explained by myelin gliosis and myelination ,respectively.

Magnetic resonance imaging of the supra-cervical fetal membrane detects an increased risk of prelabor rupture of membranes.

Objective: In 10% of term deliveries and 40% of preterm deliveries, the fetal membrane (FM) ruptures before labor. However, the ability to predict these cases of premature rupture of membranes (PROM) and preterm premature rupture of membranes (PPROM) is very limited. In this paper, our objective was to determine whether a prediction method based on T2 weighted magnetic resonance imaging (MRI) of the supra-cervical FM could predict PROM and PPROM. Methods: This prospective cohort study enrolled 77 women between the 28th and 37th weeks of gestation. Two indicators of fetal membrane defects, including prolapsed depth >5 mm and signal abnormalities, are investigated for our prediction. Fisher's exact test was used to determine whether prolapsed depth >5 mm and/or signal abnormalities were associated with PROM and PPROM. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for prolapsed depth >5 mm, signal abnormalities, and the combination of prolapsed depth >5 mm and signal abnormalities. Result: Among 12 women with PROM (5 preterm and 7 term, prior to labor onset), 9 had membrane prolapse >5 mm and 5 had FM signal abnormalities. Among 65 women with rupture of membranes at term, 2 had membrane prolapse >5 mm and 1 had signal abnormalities. By Fisher's exact test both indicators, membrane prolapse >5 mm and signal abnormalities, were associated with PROM (P<0.001, P<0.001) and PPROM (P=0.001, P<0.001). Additionally, membrane prolapse >5 mm, signal abnormalities, and the combination of the two indicators all demonstrated high specificity for predicting PROM (96.9%, 98.5%, and 100%, respectively) and PPROM (90.3%, 97.2%, and 100%, respectively). Conclusion: MRI can distinguish the supra-cervical fetal membrane in vivo and may be able to identify women at high risk of PPROM.

Age-related Change of the Dimensions of the Cricoid Cartilage in Adults.

OBJECTIVES: To measure the dimensions of the cricoid cartilage in adults and to investigate the age-related change of the dimensions of the cricoid cartilage. METHODS: After performing the multiplanar reconstruction and correcting the slant of the cervical computed tomography scans, the transverse and anteroposterior internal diameters of the inlet (TD-in and APD-in) and outlet (TD-out and APD-out) of the cricoid cartilage were measured, respectively. The angle between the arch and lamina of the cricoid cartilage in the middle sagittal plane was measured. The ratios of transverse to anteroposterior diameter for the inlet (Ratio-in) and outlet (Ratio-out) of the cricoid cartilage were calculated, respectively. RESULTS: A total of 1200 adults were included in this study, with 600 males and 600 females. The TD-in is the smallest cricoid diameter and the APD-in is the largest cricoid diameter. The mean cricoid diameters and the cricoid angle in males were larger than those in females. The cricoid inlet is oval shaped and the cricoid cartilage is "funnel-shaped" in the middle sagittal plane. The shape of the outlet of the cricoid cartilage varies greatly among individuals. In males, the APD-in and APD-out were negatively correlated with age while the Ratio-in and Ratio-out was positively correlated with age. In females, the APD-out were negatively correlated with age while the Ratio-out was negatively correlated with age. CONCLUSIONS: The dimensions of the cricoid cartilage change as age advances in adult population and the sexual dimorphism of the cricoid outlet occurs after 50 years old.

In vivo Assessment of Supra-Cervical Fetal Membrane by MRI 3D CISS: A Preliminary Study.

In approximately 8% of term births and 33% of pre-term births, the fetal membrane (FM) ruptures before delivery. In vitro studies of FMs after delivery have suggested the series of events leading to rupture, but no in vivo studies have confirmed this model. In this study, we used a three-dimensional constructive interference in steady state (3D-CISS) sequence to examine the FM at the cervical internal os zone during pregnancy; 18 pregnant women with one to three longitudinal MRI scans were included in this study. In 14 women, the FM appeared normal and completely intact. In four women, we noted several FM abnormalities including cervical funneling, chorioamniotic separation, and chorion rupture. Our data support the in vitro model that the FM ruptures according to a sequence starting with the stretch of chorion and amnion, then the separation of amnion from chorion, next the rupture of chorion, and finally the rupture of amnion ruptures. These findings hold great promise to help to develop an in vivo magnetic resonance imaging marker that improves examination of the FMs.

A small supernumerary marker chromosome resulting in mosaic partial tetrasomy 4q26-q31.21 in a foetus with multiple congenital malformations.

A parental diagnosis was performed for an unborn foetus of a healthy couple, who was due for ultrasound detection of multiple malformations and abnormal amniotic fluid karyotypes. For an accurate diagnosis, routine G-banding analysis and next generation sequencing (NGS) were carried out. Finally, conventional cytogenetic analysis suggested that the foetus had a karyotype of47,XX,+mar[52]/46,XN, meanwhile NGS also revealed a partial tetrasomy of 27.84Mb from 4q26-q31.21 (117,385,735-145,225,759), and G-banding analysis excluded the couple to have carried the 4q26-q31.21 duplication. We have identified a de novo mosaic small supernumerary marker chromosomes (sSMC) derived from 4q26-q31.21 in a foetus with hemivertebra, polydactyly, abnormal ears, and heart and ventricular septal defect.