Comparative Study On Diagnosis Of Fetal Dysplasia Of Spine And Spinal Cord Between Ultrasonography And MRI

ObjectiveThe objective of this study was to explore the value of US and MRI in detecting fetal spine and spinal cord anomalies; to estimate the accuracy and reliability of US in detecting fetal spine and spinal cord anomalies; to comprehend the advantages and disadvantages of MRI in displaying the anatomy of fetal spine and spinal cord anomalies, which can provide the foundation of imaging diagnosis for aristogenesis and termination of pregnancy reasonably.Materials and MethodsThirty-three women with complicated pregnancies, age from 22 to 41 years (average 28.4years), gestation from 23～38 weeks (average 30.1 weeks),were studied with MR within 72h after ultrasound (US) studies and revealed fetal spine with irregular, vertebral canal widened partily and anomalies of spinal curvature. T2-weighted MR imaging was performed using HASTE and T1-weighted MR imaging was using FLASH. Comparison of the diagnosis of US and MRI were done with postnatal follow-up findings.Results Of the 33 cases,33 fetus were found, lost 1 cases, follow-up in 2 case, the three cases are not included in this study, a total of 30 cases of follow-up.1, The diagnose accordance rate of US and MRI:antenatal sonographic diagnose correctly 8 cases in 19 cases of fetal spine with irregular,3 cases of sacral meningocele,1 case of invisible spina bifida, 1 case of meningomyelocele,3 cases of hemivertebrae, the diagnose accordance rate of US is 42%(8/19), but 1 case of hemivertebrae and 1 case of butterfly vertebra were missed diagnosis by MRI, the diagnose accordance rate of MRI is 90%(17/19). Antenatal sonographic diagnose correctly 0 in 7 cases vertebral canal widened partily, while the diagnose accordance rate of MRI is 100%(7/7); Antenatal sonographic diagnose correctly 2 in 4 cases of anomalies of spinal curvature,1 case of caudal regression syndrome and 1 case of cervical vertebrae retroflection excessus, the diagnose accordance rate of US is 50%(2/4), but 1 case of dorsal dermal sinus was missed diagnosis by MRI, the diagnose accordance rate of MRI is 75%(3/4).2, The advantage of MRI:By MRI study, one cases were conformed their ultrasound diagnosis, eleven cases were completed their ultrasound diagnosis, nine cases were made the same diagnosis as ultrasound and six cases were corrected diagnosis. By MRI and ultrasound study one case of hemivertebra, one case of butterfly vertebra and one case of dorsal dermal sinus were missed diagnosis. US had limits and low specificity especially in fetal spinal cord.In patients with abnormal vertebrae and/or spinal cord, ultrasound could clearly detect lesions only in meningomyelocele, meningocele, big invisible spina bifida, cervical vertebrae retroflection excessus and made a definite diagnosis. While in fetus with hemivertebrae, arachnoid cystis in vertebral canal, tight filum terminale, syringomyelia, diastematomyelia, ultrasound can only shows the irregular arrangements of the vertebrae and the local enlargement of vertebrae canal, without detecting the spinal conditions. Ultrasound can also not detecting the spinal conditions in meningomyelocele, meningocele, hemivertebrae and scoliolosis. MRI can show meningomyelocele, meningocele, but also show the lesion position accurately as its widely visual fields; Ultrasound can only shows one sacral canal cystic in 3 cases of arachnoid cystis in vertebral canal, but this case MRI show 2 cysts situated in sacral canal and lumbar spinal canal, and combined with tight filum terminale. While in fetus with arachnoid cystis in vertebral canal, tight filum terminale, syringomyelia, diastematomyelia, MRI specificity could clearly detect lesions and made a definite diagnosis. MRI could clearly show foramen magnum stenosis and spinal cord was extruded; Ultrasound can only shows lateral ventricle expand and the local enlargement of vertebrae canal in Chiari I malformation, but MRI T2WI sagittal image show sharpening tonsil of cerebellum ingress into spinal canal of the upper cervical vertebrae through the foramen magnum; In the case with over-retroflection of cervical vertebrae, ultrasound showed unnatural curvature of cerebral vertebrae, not so obviously as in MRI.But MRI had more disadvantages in detecting fetal vertebrae and its abnormalities, it also only shows the irregular arrangements of the vertebrae and scoliosis. Besides, both MRI and ultrasound had low detection to the local skin defects and hypotrichosis in fetal back.Conclusion1, Being capable of directly displaying the spinal cord, the lesions intuitively and its relationship, MRI had more advantages than ultrasound in displaying fetal anomaly of spinal cord, MR imaging is a valuable complement to sonography in difficult cases and diagnostic accuracy can be significantly improved.2, MRI had more disadvantages in detecting fetal vertebrae and its abnormalities.3, Although it has certain limitations in displaying fetal anomaly of spine and spinal cord, the transabdominal US is still a significant method. Using MRI on the base of Ultrasonography can improve the detection rate of fetal anomaly of spine and spinal cord, and can be applied to guide the clinical treatment timely, avoid the occurrence of birth defect and alleviate the burden of society and family.