The deleterious effects of radiation exposure in children

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1 J Neurosurg Pediatrics 13: , 2014 AANS, 2014 Results of a North American survey of rapid-sequence MRI utilization to evaluate cerebral ventricles in children Clinical article Eric M. Thompson, M.D., Lissa C. Baird, M.D., and Nathan R. Selden, M.D., Ph.D. Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon Object. Growing concern about potential adverse effects of ionizing radiation exposure during imaging studies is particularly relevant to the pediatric population. To decrease radiation exposure, many institutions use rapid-sequence (or quick-brain) MRI to evaluate cerebral ventricle size. There are obstacles, however, to widespread implementation of this imaging modality. The purpose of this study was to define and quantify these obstacles to positively affect institutional and governmental policy. Methods. A 9-question survey was ed to pediatric neurosurgeons who were either members or candidate members of the American Society of Pediatric Neurosurgeons at every one of 101 institutions in the US and Canada having such a neurosurgeon on staff. Responses were compiled and descriptive statistics were performed. Results. Fifty-six institutions completed the survey. Forty-four (79%) of the 56 institutions currently have a rapid-sequence MRI protocol to evaluate ventricle size, while 36 (64%) use it routinely. Of the 44 institutions with a rapid-sequence MRI protocol, 29 (66%) have had a rapid-sequence MRI protocol for less than 5 years while 39 (89%) have had a rapid-sequence MRI protocol for more than 10 years. Thirty-six (88%) of 41 rapid-sequence MRI users responding to this question obtain a T2-weighted rapid-sequence MRI while 13 (32%) obtain a T1-weighted rapid-sequence MRI. Twenty-eight (64%) of 44 institutions never use sedation while an additional 12 (27%) rarely use sedation to obtain a rapid-sequence MRI (less than 5% of studies). Of the institutions with an established rapidsequence MRI protocol, obstacles to routine use include lack of emergency access to MRI facilities in 18 (41%), lack of staffing of MRI facilities in 12 (27%), and the inability to reimburse a rapid-sequence MRI protocol in 6 (14%). In the 12 institutions without rapid-sequence MRI, obstacles to implementation include lack of emergency access to MRI facilities in 8 (67%), lack of staffing of MRI facilities in 7 (58%), the inability to reimburse in 3 (25%), and lack of administrative support in 3 (25%). To evaluate pediatric head trauma, 53 (96%) of 55 institutions responding to this question use ncontrast CT, institution uses rapid-sequence MRI, and only 2 (4%) use standard MRI. Conclusions. Many North American institutions have a rapid-sequence MRI protocol to evaluate ventricle size, with most developing this technique within the past 5 years. Most institutions never use sedation, and most obtain T2-weighted sequences. The greatest obstacles to the routine use of rapid-sequence MRI in institutions with and in those without a rapid-sequence MRI protocol are the lack of emergency access and staffing of the MRI facility during nights and weekends. ( Key Words rapid sequence MRI radiation hydrocephalus ventricles technique Abbreviation used in this paper: TBI = traumatic brain injury. The deleterious effects of radiation exposure in children from CT are w well defined. 3,4 The risk of developing a radiation-induced malignancy is relative to a patient s cumulative radiation exposure and increases with exposure at younger ages. 3 Radiation exposure in children with shunted hydrocephalus is particularly concerning given their lifetime exposure to numerous head CT scans for shunt evaluation. Reported high failure rates after primary shunt insertion 5 is one factor contributing to an increased likelihood of CT exposure in younger populations. Gaskill and Marlin found that children with myelomeningocele receive on average 3.6 head CT scans during their lifetime, and an average of 6.38 rad/year (range rad/year) from radiography and CT. 7 An report found that children with complex hydrocephalus received an average of 13.4 head CT scans (range 1 94 scans) during a 5-year period. 13 This exposure to radiation is more than the annual limit of 5 rad for occupational doses 14 and 0.1 rad for the general public as specified by the US Nuclear Regulatory Commission. 15 To reduce the amount of lifetime radiation exposure in children with shunts, some institutions use rapidsequence, fast-brain, or vent-check MRI 1,2,8 12,16 that takes approximately the same amount of imaging time as a head CT scan but eliminates exposure to radiation or sedation risks. This techlogy is relatively new and its use in North America is unkwn. The purpose of this study was to evaluate the use of rapid-sequence MRI in North 636 J Neurosurg: Pediatrics / Volume 13 / June 2014

2 Rapid-sequence MRI use in North America America, to determine the primary obstacles for expanding use of this safer imaging technique, and to provide data for institutions without this resource to subsequently positively affect institutional and governmental policy. Methods A 9-question survey (Table 1) was ed to pediatric neurosurgeons who were either members or candidate members of the American Society of Pediatric Neurosurgeons at every one of 101 institutions in the US and Canada having such a neurosurgeon on staff. Only 1 individual per institution was surveyed to eliminate duplicate institutional responses. Response data were collected using Survey Monkey ( Stata (version 10.1, StataCorp LP) and Microsoft Excel were used to tabulate the results. Results Fifty-six of 101 institutions completed the survey (55% response rate). Forty-four (79%) of 56 institutions have a rapid-sequence MRI protocol to evaluate ventricle size, and 36 (82%) of those 44 institutions use it routinely. The majority of institutions have used rapid-sequence MRI for less than 5 years (29/44, 66%), obtain at least T2-weighted sequences (36/41, 88%), and never use sedation (28/44, 64%; Fig. 1). Of the 44 institutions with a rapid-sequence MRI protocol, obstacles to routine use include lack of emergency access to MRI facilities in 18 (41%), lack of staffing for MRI facilities in 12 (27%), and inability to reimburse a rapid-sequence MRI protocol from third-party payers in 6 (14%). Of those who ted the inability to reimburse a rapid-sequence MRI protocol, 3 (50%) indicated that they had made an effort to appropriately reimburse rapid-sequence MRI, while 3 (50%) were if an effort had been made. In the 12 institutions without rapid-sequence MRI, obstacles to implementation included lack of emergency access to MRI facilities in 8 (67%), lack of staffing for MRI facilities in 7 (58%), inability to reimburse a rapid-sequence MRI protocol from third-party payers in 3 (25%), and lack of administrative support in 3 (25%). Of those with reimbursement difficulties, 1 had t made an effort to reimburse rapid-sequence MRI, 1 had made an effort, and 1 was if any effort had been made. To evaluate npenetrating traumatic brain injury (TBI), 53 (96%) of 55 institutions responding to this question use ncontrast head CT while 2 (4%) use standard MRI. Forty-nine (89%) of the 55 institutions have a radiation reduction protocol for CT head imaging in children while 3 (5%) do t and 3 (5%) were. Discussion Based on the results of this survey, a large number of institutions in the US and Canada have a rapid-sequence MRI protocol to evaluate ventricle size in pediatric patients. Only 81% of these institutions, however, routinely use this techlogy. The most commonly cited obstacles for the routine use of rapid-sequence MRI were similar among J Neurosurg: Pediatrics / Volume 13 / June 2014 those institutions with a rapid-sequence MRI protocol and those without a protocol: lack of emergency access to MRI facilities, lack of staffing for MRI facilities during nights and weekends, and inability to obtain reimbursement from third-party payers for rapid-sequence MRI. Based on survey responses, the availability of rapidsequence MRI protocols is relatively new in many institutions and rapid-sequence MRI use is rapidly increasing. Sixty-six percent of institutions have used a rapid-sequence MRI protocol for less than 5 years and 89% have had a rapid-sequence MRI protocol for less than 10 years. Ideally, within an 5 years, all institutions caring for pediatric neurosurgical patients will use rapid-sequence MRI in lieu of CT for cerebral ventricle evaluation. Study Limitations The present study is limited by a 55% survey response rate, and further does t reflect the practices at pediatric neurosurgical services and hospitals t staffed by members or candidate members of the American Society of Pediatric Neurosurgeons. Conceivably, the nreturned surveys (45%) could be from sites that do t use rapid-sequence MRI, and thus the reported results could be skewed. Responses received were t validated directly with the respondents institutions to assure accuracy. Questions regarding barriers to rapid-sequence MRI were subjective in nature, and the survey instrument has t been previously validated. Clinical Rapid-Sequence MRI Most reports of clinical rapid-sequence MRI use have focused on the evaluation of hydrocephalus. 1,8 10,12,16 However, pathologies may be successfully screened, evaluated, and/or followed using rapid-sequence MRI, including tumors, inflammatory/demyelinating lesions, hemorrhage in children and adults, macrocephaly, intracranial cysts, Chiari malformations, congenital abrmalities, and traumas. 2,11 For trauma patients, rapid-sequence MRI has been used primarily for follow-up imaging. 11 Additionally, in 1 study 13 of 64 patients with mir TBI underwent initial evaluation with rapid-sequence MRI and ne were subsequently ted to have a missed lesion. 11 Traumatic brain injury is a potential area for expanded rapid-sequence MRI use. The present survey demonstrated that more than 96% of institutions continue to rely on ncontrast head CT scanning in the evaluation of npenetrating TBI in children. The sensitivity and specificity of rapid-sequence MRI for various findings that influence the medical and surgical management of cranial trauma have yet to be firmly established. One clearly established disadvantage of MRI in comparison with CT for the evaluation of cranial trauma, however, is insensitivity to ndisplaced skull fractures, which do t typically alter clinical management. Conversely, rapid-sequence MRI is effective in demonstrating many clinically relevant findings, such as parenchymal or extraaxial hemorrhage and mass effect, 11 and in our experience, sinus opacification sometimes associated with skull base fractures. Other potential drawbacks of using rapid-sequence MRI include the need for a parent or health care profes- 637

3 E. M. Thompson, L. C. Baird, and N. R. Selden TABLE 1: Survey questions Does your institution have a quick brain/vent check MR imaging protocol to evaluate the ventricle size in pediatric patients? How long has your institution utilized quick brain/vent check MR imaging? < 5 years 5 10 years > 10 years At your institution, what are the primary sequence(s) obtained for the quick brain/vent check MR imaging protocol? (e.g., T2 axial, T1, DWI) Is sedation used to obtain quick brain/vent check protocol MR imaging? never rarely (< 5% of studies) occasionally (5 49% of studies) frequently (50 99% of studies) always (100% of studies) If you have encountered obstacles to implementation of quick brain/vent check MR imaging what are/were they (check all that apply)? unable to reimburse quick brain/vent check study lack of emergency access to MR imaging facilities lack of staffing for MR imaging facilities lack of administrative support have t attempted to implement If quick brain/vent check is t reimbursed, has an effort been made by your institution to change reimbursement policy? t applicable if (please specify) At your institution, what is the preferred method of evaluating ventricle size in patients with an existing ventriculoperitoneal shunt? CT quick brain/vent check MRI standard MRI At your institution, what is the preferred method of evaluating the brain in patients with a GCS of 14 or 15 with n-penetrating traumatic brain injury? CT quick brain/vent check MRI standard MRI At your institution, does a CT brain imaging protocol exist to reduce radiation exposure in pediatric patients? 638 J Neurosurg: Pediatrics / Volume 13 / June 2014

4 Rapid-sequence MRI use in North America suspected cervical trauma. 6 In the future, it is possible that MRI-based urgent evaluation of npenetrating craniocervical trauma in children could substantially reduce radiation exposure in this patient population. Conclusions Adoption and utilization of rapid-sequence MRI protocols in the US and Canada are increasing. Key obstacles to widespread utilization of rapid-sequence MRI are lack of emergency or off-hour MRI availability, lack of available MRI technicians to perform these studies, and barriers to study reimbursement. Quantification of rapidsequence MRI use in the US and Canada and objective identification of barriers to adoption and routine use are important to influence institutional and governmental policies regarding this important imaging technique. Expanded use of MRI offers the potential of minimizing the adverse effects of radiation exposure in children. Ackwledgments We wish to thank all of our colleagues who generously took the time to complete the survey. We also wish to thank Andy Rekito, M.S., for figure preparation and Shirley McCartney, Ph.D., for editorial assistance. Disclosure The authors report conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Author contributions to the study and manuscript preparation include the following. Conception and design: all authors. Acquisition of data: Thompson. Analysis and interpretation of data: Thompson. Drafting the article: all authors. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Selden. Study supervision: Selden. Fig. 1. Graphs of rapid-sequence MRI use characteristics of institutions with a quick-brain MRI protocol. The graphs show responses to the following survey questions: How long has your institution utilized quick brain/vent check MR imaging? (A); At your institution, what are the primary sequence(s) obtained for the quick brain/vent check MR imaging protocol? (e.g. T2 axial, T1, DWI) (B); and Is sedation used to obtain quick brain/vent check protocol MR imaging? (C). Note that institution reported the use of diffusion weighted imaging as part of their rapid-sequence MRI protocol. sional to accompany the patient into the MRI machine to aid with quality image acquisition, concerns with medical device and implant incompatibility, and inadvertent reprogramming of some programmable shunts. Notably, the Medtronic SynchroMed II intrathecal infusion pump is reported to be safe at field strengths 3T, and the Cyberonics Vagus Nerve Stimulator Therapy System is reported to be safe at field strengths 3T as long as a head or local transmit/receive coil is used. Recently, a quick-spine MRI nsedation imaging protocol has been investigated for its potential to replace cervical CT or sedated diagstic MRI in patients with J Neurosurg: Pediatrics / Volume 13 / June 2014 References 1. Ashley WW Jr, McKinstry RC, Leonard JR, Smyth MD, Lee BC, Park TS: Use of rapid-sequence magnetic resonance imaging for evaluation of hydrocephalus in children. J Neurosurg 103 (2 Suppl): , Ba-Ssalamaha A, Schick S, Heimberger K, Linnau KF, Schibany N, Prokesch R, et al: Ultrafast magnetic resonance imaging of the brain. Magn Reson Imaging 18: , Berrington de González A, Mahesh M, Kim KP, Bhargavan M, Lewis R, Mettler F, et al: Projected cancer risks from computed tomographic scans performed in the United States in Arch Intern Med 169: , Brenner DJ, Hall EJ: Computed tomography an increasing source of radiation exposure. N Engl J Med 357: , Drake JM, Kestle JR, Milner R, Cinalli G, Boop F, Piatt J Jr, et al: Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus. Neurosurgery 43: , Farrell BT, Pollock J, Riccelli L, Anderson J, Bardo D, Guillaume D: Preliminary experience with quick-spine magnetic resonance imaging for evaluation of cervical spine trauma in children. J Neurosurg 119:A547, 2013 (Abstract) 7. Gaskill SJ, Marlin AE: Radiation exposure in the myelomeningocele population. Pediatr Neurosurg 28:63 66,

5 E. M. Thompson, L. C. Baird, and N. R. Selden 8. Iskandar BJ, Sansone JM, Medow J, Rowley HA: The use of quick-brain magnetic resonance imaging in the evaluation of shunt-treated hydrocephalus. J Neurosurg 101 (2 Suppl): , Koral K, Blackburn T, Bailey AA, Koral KM, Anderson J: Strengthening the argument for rapid brain MR imaging: estimation of reduction in lifetime attributable risk of developing fatal cancer in children with shunted hydrocephalus by instituting a rapid brain MR imaging protocol in lieu of head CT. AJNR Am J Neuroradiol 33: , Miller JH, Walkiewicz T, Towbin RB, Curran JG: Improved delineation of ventricular shunt catheters using fast steadystate gradient recalled-echo sequences in a rapid brain MR imaging protocol in nsedated pediatric patients. AJNR Am J Neuroradiol 31: , Missios S, Quebada PB, Forero JA, Durham SR, Pekala JS, Eskey CJ, et al: Quick-brain magnetic resonance imaging for nhydrocephalus indications. Clinical article. J Neurosurg Pediatr 2: , O Neill BR, Pruthi S, Bains H, Robison R, Weir K, Ojemann J, et al: Rapid sequence magnetic resonance imaging in the assessment of children with hydrocephalus. World Neurosurg 80:e307 e312, Pindrik J, Huisman TA, Mahesh M, Tekes A, Ahn ES: Analysis of limited-sequence head computed tomography for children with shunted hydrocephalus: potential to reduce diagstic radiation exposure. Laboratory investigation. J Neurosurg Pediatr 12: , United States Nuclear Regulatory Commission: Subpart C occupational dose limits. 10 C.F.R ( nrc.gov/reading-rm/doc-collections/cfr/part020/part html) [Accessed March 2, 2014] 15. United States Nuclear Regulatory Commission: Subpart D radiation dose limits for individual members of the public. 10 C.F.R ( [Accessed March 2, 2014] 16. Wait SD, Lingo R, Boop FA, Einhaus SL: Eight-second MRI scan for evaluation of shunted hydrocephalus. Childs Nerv Syst 28: , 2012 Manuscript submitted October 29, Accepted February 27, Please include this information when citing this paper: published online April 11, 2014; DOI: / PEDS Address correspondence to: Nathan R. Selden, M.D., Ph.D., Neurological Surgery, Oregon Health & Science University, Mail code CH8N, 3303 S.W. Bond Ave., Portland, OR seldenn@ohsu.edu. 640 J Neurosurg: Pediatrics / Volume 13 / June 2014