Diagnostic value of spinal ultrasound in infants - adapted from Radiology 1996;200:383-8 - Tips from

Author: Barbara Apgar
Date: Nov 15, 1996

Diagnostic imaging of the spinal canal in the pediatric population is primarily performed to evaluate the presence of congenital malformations, trauma, neoplasms and inflammation. Although magnetic resonance imaging (MRI) is considered the diagnostic modality of choice, availability is limited, cost is high and sedation is often required. An advantage of MRI is its excellent tissue differentiation. Rohrschneider and associates compared the diagnostic value of spinal ultrasonography with MRI in pediatric patients suspected of having a spinal disorder. An indispensable condition for spinal ultrasound is the presence of an acoustic window, which in infants is provided by the incomplete ossification of the dorsal spinal elements.

The study included a series of 30 children (mean age: 5.5 months) who underwent a total of 38 spinal ultrasound scans. Findings on ultrasound were compared with results of MRI.

MRI revealed a normal spinal canal in 14 patients and congenital spinal anomalies in 22 patients, including some with multiple concurrent anomalies. When MRI was compared with ultrasound, consensus was achieved in 32 of 38 examinations. Partial consensus was achieved in five additional scans. In the two patients with intraspinal neoplasms, MRI depicted the total extent of the process much better than did ultrasound, although the diagnosis of an intraspinal neoplasm was made correctly with ultrasound imaging. No consensus was reached in one examination.

In all 24 examinations with abnormal MRI findings, ultrasound was also able to depict the abnormality. Thirteen of 14 examinations with normal MRI findings were also found to be normal on ultrasound. Whenever spinal ultrasound was classified as normal, the corresponding MRI finding confirmed the normal anatomy.

Ultrasound exhibits several advantages over MRI. Section planes can be varied to demonstrate longitudinal structures. Motion artifacts, which can considerably reduce the quality of MRI, are not as much of a consideration. When compared with MRI, spinal ultrasound in infants seemed to exhibit good sensitivity for identification of disorders situated below the midthoracic level.

The authors stress that in cases of any pathology, especially if surgical intervention is considered, MRI should be performed to demonstrate a more detailed view of a particular abnormality. The information from the ultrasound scan can be used to focus the MRI study to the expected site of abnormality to obtain high-quality scans with minimum effort.

The authors conclude that spinal ultrasound is a valuable tool for the diagnosis of congenital malformation. It can be used at the bedside of critically ill infants, requires a minimum of patient preparation and can quickly provide a reliable diagnosis. Spinal ultrasound represents an ideal screening test for congenital anomalies of the lower spine in infants. Although spinal neoplasms can be adequately demonstrated with ultrasound, MRI is the imaging method of choice for this indication.

Rohrschneider WK, et al. Diagnostic value of spinal US: comparative study with MR imaging in pediatric patients. Radiology 1996;200:383-8.

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