Approach to the diagnosis of skeletal dysplasias: Experience at a center with limited resources

PURPOSE

A fetus with skeletal disorder poses diagnostic challenges in a resource-poor setting with limited management options. The objective of the study was to develop a step-by-step approach for the diagnosis of skeletal dysplasia in light of the limited resources available.

METHODS

An algorithmic approach was used. The assessment for lethality was the first step, followed by the evaluation for fractures. In cases without evidence of fracture, severe constriction of thorax or associated polydactyly were searched for. In cases without severe thoracic constriction, the severity of micromelia was evaluated. After delivery, fetal examination was done to ascertain the etiology.

RESULTS

During the 6-year period, 41 cases with shortened long bones were fully evaluated. Lethality was suspected in 30 cases. Fracture and beading were present in eight cases, and severe thoracic constriction with polydactyly was observed in seven cases. Mild micromelia was seen in 19 cases and severe micromelia in 7 cases. Among lethal skeletal dysplasias, thanatophoric dysplasia was most common (six cases). Among nonlethal skeletal dysplasias, achondroplasia was seen in eight cases.

CONCLUSIONS

Lethality of skeletal dysplasia could be predicted on prenatal ultrasound with 100% accuracy. The step-by-step approach was helpful to characterize skeletal dysplasias. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:529-539, 2016.

Reducing radiation exposure in early-onset scoliosis surgery patients: novel use of ultrasonography to measure lengthening in magnetically-controlled growing rods

BACKGROUND CONTEXT

Magnetically-controlled growing rod (MCGR) technology has been reported for the treatment of early-onset scoliosis (EOS). Such technology allows for regular and frequent outpatient rod distractions without the need for additional surgery. However, pre- and postdistraction spine radiographs are required to verify the amount of lengthening. This increased exposure to ionizing radiation in developing children significantly increases their risk profile for radiation-induced cancer and noncancerous morbidity.

PURPOSE

This study addressed the first and novel application and reliability of the use of ultrasonography, that has no ionizing radiation exposure, as an alternative to plain radiographs in the visualizing and confirming of rod distractions.

STUDY DESIGN

A prospective study.

PATIENT SAMPLE

Six EOS patients who underwent surgical treatment with MCGRs were prospectively recruited.

OUTCOME MEASURES

Imaging measurements based on ultrasound and plain radiographs.

METHODS

All patients were imaged via ultrasound, ease of rod identification was established, and the reliability and reproducibility of optimal reference point selection assessed blindly by three individuals. The clinical algorithm, using ultrasound, was subsequently implemented. Plain radiographs served as controls.

RESULTS

Assessment of the rod's neck distance on ultrasound demonstrated a high degree of interrater reliability (a=0.99; p<.001). Intrarater reliability remained high on repeat measurements at different time intervals (a=1.00; p<.001). Satisfactory interrater reliability was noted when measuring the rod's neck (a=0.73; p=.010) and high reliability was noted in assessing the housing of the rod (a=0.85; p=.01) on plain radiographs. Under blinded conditions, 2 mm rod distraction measured on radiographs corresponded to 1.7 mm distraction on the ultrasound (standard deviation: 0.24 mm; p<.001). Subsequently, the clinical algorithm using ultrasound, instead of radiographs, has been successfully implemented.

CONCLUSIONS

This is the first study to report the use of a novel technique using noninvasive, nonionizing ultrasound to reliably document rod distractions in EOS patients. A high level of inter- and intrarater reliabilities were noted. More importantly, the use of ultrasonography may result in fewer whole spine radiographs from being taken in patients who have had MCGRs implanted for EOS; thereby decreasing their exposure to ionizing radiation and the potential risk of future radiation-induced diseases.

A sonographic approach to prenatal classification of congenital spine anomalies

Objective: To develop a classification system for congenital spine anomalies detected by prenatal ultrasound. Methods: Data were collected from fetuses with spine abnormalities diagnosed in our institution over a five-year period between June 2005 and June 2010. The ultrasound images were analysed to determine which features were associated with different congenital spine anomalies. Findings of the prenatal ultrasound images were correlated with other prenatal imaging, post mortem findings, post mortem imaging, neonatal imaging, karyotype, and other genetic workup. Data from published case reports of prenatal diagnosis of rare congenital spine anomalies were analysed to provide a comprehensive work. Results: During the study period, eighteen cases of spine abnormalities were diagnosed in 7819 women. The mean gestational age at diagnosis was 18.8w ± 2.2 SD. While most cases represented open NTD, a spectrum of vertebral abnormalities were diagnosed prenatally. These included hemivertebrae, block vertebrae, cleft or butterfly vertebrae, sacral agenesis, and a lipomeningocele. The most sensitive features for diagnosis of a spine abnormality included flaring of the vertebral arch ossification centres, abnormal spine curvature, and short spine length. While reported findings at the time of diagnosis were often conservative, retrospective analysis revealed good correlation with radiographic imaging. 3D imaging was found to be a valuable tool in many settings. Conclusions: Analysis of the study findings showed prenatal ultrasound allowed detection of disruption to the normal appearances of the fetal spine. Using the three features of flaring of the vertebral arch ossification centres, abnormal spine curvature, and short spine length, an algorithm was devised to aid with the diagnosis of spine anomalies for those who perform and report prenatal ultrasound.

Normal ascent of the conus medullaris: a post-mortem foetal MRI study

OBJECTIVES

The position of the conus medullaris is considered abnormal if it ends below lumbar vertebrae three (L3) at birth. We used magnetic resonance imaging (MRI) to measure the position of the conus in post-mortem foetuses, to investigate the timing of normal ascent.

METHODS

The position of the conus in 84 post-mortem foetuses (mean gestation 26.3 weeks; range 14-41 weeks) was identified using 3D MRI datasets. A numerical scale was used for vertebral levels, from 1 (S2) to 15 (T12).

RESULTS

There was significant ascent of the conus medullaris with increasing gestation. At 20 weeks gestation, an estimated 84.2% (95% confidence interval (CI): 72.9, 93.2%) of foetuses have a conus position of L4/5 or higher, but only 22.8% (95% CI 11.7, 34.9%) at L3 or higher. By 26 weeks, an estimated 50.7% (95% CI 34.1, 67.5) will have reached L3, and 94.8% (95% CI 87.0, 98.5%) reach L3 by 40 weeks.

CONCLUSION

There is regular ascent of the conus throughout foetal life. Although growth for each individual foetus may be non-linear, most foetuses have a conus level within the normal adult range by 33 weeks gestation.

Detailed ultrasound screening in the second trimester: pictorial essay of normal fetal anatomy

Today, ultrasound is the main diagnostic tool in the prenatal detection of congenital abnormalities. Therefore, ultrasound examination should be offered to all pregnant women. A detailed sonographic examination of the fetus is usually performed between 18 and 22 weeks of pregnancy. The accurate recognition of normal fetal anatomy is very important for the detection of both minor and major defects. The purpose of this pictorial essay is to show fetal anatomic structures, which have to be examined between the 18(th) and 22(nd) weeks of pregnancy, and present their standard measurements systematically and thoroughly in accordance with sonographically obtained ideal sections.

Evaluation of fetal spine biometry between 11 and 14 weeks of gestation

This study was designed to establish a fetal spine nomogram for age 11 through 14 weeks of gestation and to document relations among fetal spine length, distance and angle. These parameters were prospectively measured during the first trimester of singleton pregnancies, along with nuchal translucency, over a 3-year period. A total of 430 fetuses were included in the study. The regression equations among fetal spine parameters and gestational age were as follows: Spine length (mm) = 1.116 x gestational age (days) - 59.169; spine distance (mm) = 1.079 x gestational age (days) - 59.038; head-spine angle = 0.740 x gestational age (days) + 4.735; spine length:spine distance ratio = -0.002 x gestational age (days) + 1.234. Prenatal age-specific reference intervals for fetal spine biometry between 11 and 14 weeks of gestation may assist in evaluation of fetuses investigated for genetic abnormalities that can be expressed by deviation in spine length, distance, or angle.

Three- and 4-dimensional ultrasound in obstetric practice: does it help?

OBJECTIVE

The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas.

METHODS

A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed.

RESULTS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures.

CONCLUSIONS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.

Fetal spine ossification: the gender and individual differences illustrated by ultrasonography

The spatial and temporal pattern of manifestation of ossification nuclei of the spinal column in fetal life have been well established by histologic and radiologic studies. Sonographic evaluation of the fetal spine depends on visualization of the ossification centers, but the sequence of development of ossification centers in the vertebral column obtained by embryologists and sonographers and radiology are conflicting. We carried out a longitudinal study to establish the ultrasonographic appearance and timing of development of primary ossification centers of the fetal spine in the first and second trimesters of pregnancy. A total of 80 mothers were evaluated during their pregnancy with two echographic controls; in the first trimester, the spine length was measured and, in the second trimester of pregnancy, the timing of ossification of the bodies and neural arches of sacral vertebrae and the difference in appearance between the female and male genders were evaluated. Spinal length measurements obtained in the first trimester and percentage of detection of sacral vertebral structures increased progressively with a regular pattern in relation to gestational age. Spinal length at first ultrasound examination was slightly correlated with time of appearance of sacral bodies and arches. Ossification timing was significantly earlier in females than in males. The study has attempted to improve our understanding of the sonographic detection of the spinal ossification. Data presented give some further information on the stages of appearance of sacral vertebrae body centers during intrauterine development. Differences between genders and interindividual variations in ossification timing were observed at a very early stage of development. This could be of value when fetal growth is evaluated. Moreover, further knowledge of spinal development may be useful for early diagnosis of spinal abnormalities and for fetal biometrics.

Spine length measurement in the first trimester of pregnancy

OBJECTIVES

The aim of the study was to evaluate spine length as an indicator of skeletal growth in the first trimester of pregnancy and to provide a nomogram of spine length at the end of the first trimester of pregnancy.

METHODS

The study was carried out on 420 single pregnancies, at gestational ages ranging from 11 to 14 weeks, using high-resolution transabdominal echography. Biparietal diameter and crown-rump length (CRL) were measured to date the pregnancy. Using the same scanning plane used to measure CRL, the whole spine length in antero-dorsal position can be visualized as a double hyperechoic line from 10 weeks of gestation onwards. Spine length was measured three times by one observer and the mean of the three measurements was considered as definitive. Forty fetuses had multiple measurements for interobserver and intraobserver error analysis.

RESULTS

Linear relationship between spine length, and gestational age, biparietal diameter and CRL were demonstrated. Spine length (millimetres) as a function of gestational age (days) was expressed by the regression equation: spine length = 1.09 x (gestational age in days) -60.56, with a determination coefficient of R(2) = 0.744. Spine length ranged from 21.5 mm at 11 weeks to 41.9 mm at 14 weeks.

CONCLUSION

The data obtained showed that spine length increased progressively from the end of the first trimester to the beginning of the second. A high correlation between spine length, gestational age, biparietal diameter, and CRL was observed. Spine length measurement could therefore be considered a good indicator of fetal growth.

The role of three-dimensional ultrasound in obstetrics

Three-dimensional ultrasound is a relatively new imaging modality with several potential advantages over conventional two-dimensional sonography. There is now increasing evidence that three-dimensional ultrasound can in many ways assist in the examination of the fetus. The enthusiasm generated by some groups, however, is not universally shared. It is the aim of this review to summarize the contemporary role of three-dimensional ultrasound in obstetric sonography by giving a critical appraisal of the relevant literature published recently, with emphasis on first and second trimester anatomy and fetal organ and placenta volumetry.