Fluoroscopy-guided insertion of nasojejunal tubes in children - setting local diagnostic reference levels.

BACKGROUND: Little is known about the radiation burden from fluoroscopy-guided insertions of nasojejunal tubes (NJTs) in children. There are no recommended or published standards of diagnostic reference levels (DRLs) available. OBJECTIVE: To establish reference dose area product (DAP) levels for the fluoroscopy-guided insertion of nasojejunal tubes as a basis for setting DRLs for children. In addition, we wanted to assess our local practice and determine the success and complication rates associated with this procedure. MATERIALS AND METHODS: Children who had NJT insertion procedures were identified retrospectively from the fluoroscopy database. The age of the child at the time of the procedure, DAP, screening time, outcome of the procedure, and any complications were recorded for each procedure. As the radiation dose depends on the size of the child, the children were assigned to three different age groups. The sample size, mean, median and third-quartile DAPs were calculated for each group. The third-quartile values were used to establish the DRLs. RESULTS: Of 186 procedures performed, 172 were successful on the first attempt. These were performed in a total of 43 children with 60% having multiple insertions over time. The third-quartile DAPs were as follows for each age group: 0-12 months, 2.6 cGy cm(2); 1-7 years, 2.45 cGy cm(2); >8 years, 14.6 cGy cm(2). High DAP readings were obtained in the 0-12 months (n = 4) and >8 years (n = 2) age groups. No immediate complications were recorded. CONCLUSION: Fluoroscopy-guided insertion of NJTs is a highly successful procedure in a selected population of children and is associated with a low complication rate. The radiation dose per procedure is relatively low.

Is there a causal relationship between open spinal dysraphism and Chiari II deformity? A study using in utero magnetic resonance imaging of the fetus.

BACKGROUND: Chiari II deformity is associated with open spinal dysraphism. A causal relationship has been proposed by McLone and Knepper. This article evaluates that hypothesis. OBJECTIVE: To establish the frequency of Chiari II deformity in fetuses with open spinal dysraphism, assess whether meningocele sac neck area and volume influence the severity of posterior fossa changes, and assess whether the severity of associated findings (ventriculomegaly, amount of extracerebral CSF) are associated with Chiari II deformity. METHODS: Sixty-five fetuses with open spinal dysraphism were compared with gestationally aged matched "normal" fetuses on ultrafast MR images. Cerebellar vermis and bony posterior fossa surface area were measured on midline sagittal images. Hindbrain herniation was noted if present. In the open spinal dysraphic group, sac neck area and volume were measured. Ventriculomegaly was assessed by linear measurement of the trigone of the lateral ventricle and extracerebral CSF depth was measured maximally over the lateral surface of the cerebral hemispheres. RESULTS: Fifteen of 65 fetuses with open spinal dysraphism did not have Chiari II deformity. Neck area and volume of the sac did not correlate with the presence of Chiari II deformity or reduction in bony posterior fossa size. CONCLUSION: A relatively high proportion of fetuses with open spinal dysraphism do not have Chiari II deformity in utero. There is a lack of correlation between indicators of spinal dysraphism severity and the extent of the posterior fossa abnormality. This raises some interesting questions about the causality of the Chiari II deformity.