Background: The definition of normal values is a prerequisite for the reliable evaluation of abnormality in the lumbar spine, such as spinal canal stenosis or dural ectasia in patients with Marfan syndrome. Values for vertebral body diameter (VBD) and dural sac diameter (DSD) for the lumbar spine have been published in adults. In children, normal values have been established using conventional radiography or myelography, but not by MRI. Objective: To define normal values for the sagittal diameter of the vertebral body and dural sac, and to calculate a dural sac ratio (DSR) in the lumbosacral spine (L1-S1) in healthy children using MRI. Materials and methods: A total of 75 healthy children between 6years and 17years of age were examined using a sagittal T2-weighted sequence. Sagittal VBD and DSD were measured and a DSR was calculated. This was a retrospective and cross-sectional study. Results: With increasing age there is a significant increase of VBD, a slight increase of DSD, and a slight decrease of DSR. There is no significant sex difference. DSR in healthy children is higher than in healthy adults. Conclusions: MRI is a reliable method demonstrating the natural shape of the lumbosacral spine and its absolute values. These normal values compare well with those established by conventional radiological techniques. Our data may serve as a reference for defining dural ectasia in children with Marfan syndrom

Häffner, Nicole

Kececioglu, Deniz

Knirsch, Walter

Kurtz, Claudia

Langer, Mathias

RERO DOC Digital Library

IntroductionEvaluation of lumbar spine abnormality is nowadaysroutinely established by using MRI or CT. Historically,normal dimensions of the paediatric lumbar spine wereestablished by conventional radiography [1, 2], or mye-lography for the cervical and thoracic spine [3]. Con-ﬂicting data exist for the age-dependant increase of thesagittal diameter of the lumbar spine [1, 2]. Some studiesstate an age-dependant increase for the dimensions ofthe lumbar spine [1], while other studies deny this agedependency, discussing diﬀerent methodological factors,such as magniﬁcation [2]. Normal values for thedimensions of the paediatric lumbar spine as demon-strated by MRI or CT are lacking. Therefore, the aim ofthis study was to establish reliable values by a digitaltechnique that circumvents the methodological problemsof magniﬁcation.Some pathological entities of the lumbar spine, suchas spinal canal stenosis or lumbar dural ectasia in pa-tients with Marfan syndrome or neuroﬁbromatosismanifest even in early childhood [4–7]. In order to im-prove our understanding of these diseases, the aim ofthis study was to deﬁne normal values of the lumbarWalter KnirschClaudia KurtzNicole Ha¨ﬀnerMathias LangerDeniz KececiogluNormal values of the sagittal diameterof the lumbar spine (vertebral bodyand dural sac) in children measuredby MRIReceived: 15 September 2004Revised: 22 October 2004Accepted: 24 October 2004Published online: 6 January 2005 Springer-Verlag 2005Abstract Background: The deﬁnitionof normal values is a prerequisite forthe reliable evaluation of abnormal-ity in the lumbar spine, such asspinal canal stenosis or dural ectasiain patients with Marfan syndrome.Values for vertebral body diameter(VBD) and dural sac diameter(DSD) for the lumbar spine havebeen published in adults. In children,normal values have been establishedusing conventional radiography ormyelography, but not by MRI.Objective: To deﬁne normal valuesfor the sagittal diameter of the ver-tebral body and dural sac, and tocalculate a dural sac ratio (DSR) inthe lumbosacral spine (L1–S1) inhealthy children using MRI.Materials and methods: A total of 75healthy children between 6 yearsand 17 years of age were examinedusing a sagittal T2-weightedsequence. Sagittal VBD and DSDwere measured and a DSR was cal-culated. This was a retrospective andcross-sectional study. Results: Withincreasing age there is a signiﬁcantincrease of VBD, a slight increase ofDSD, and a slight decrease of DSR.There is no signiﬁcant sex diﬀerence.DSR in healthy children is higherthan in healthy adults. Conclusions:MRI is a reliable method demon-strating the natural shape of thelumbosacral spine and its absolutevalues. These normal values com-pare well with those established byconventional radiological tech-niques. Our data may serve as areference for deﬁning dural ectasia inchildren with Marfan syndrome.Keywords Spine Æ Normal ÆMRI Æ Dural ectasia Æ Marfan’ssyndrome Æ ChildrenPediatr Radiol (2005) 35: 419–424DOI 10.1007/s00247-004-1382-6 ORIGINAL ARTICLEW. Knirsch Æ N. Ha¨ﬀnerD. KececiogluDepartment of Pediatric Cardiology,University Children’s Hospital Freiburg,Freiburg, GermanyW. Knirsch (&)Division of Paediatric Cardiology,University Children’s Hospital Zurich,Steinwiesstrasse 75, 8032, ZurichSwitzerlandE-mail: walter.knirsch@kispi.unizh.chTel.: +41-1-2667617Fax: +41-1-2667981C. Kurtz Æ M. LangerDepartment of Radiology,University Hospital Freiburg,Freiburg, Germanyspine in healthy children between 6 years and 17 yearsof age.Materials and methodsStudy populationSagittal diameters of the lumbar spine (vertebral bodyand dural sac) were measured in 75 healthy children (32boys, 43 girls) between 6 years and 17 years of age. Thechildren were referred for MRI of the lumbosacral spinefor routine clinical indications (e.g. back pain, rheumaticdisorders, traumatic or other orthopaedic reasons). Anexclusion criterion was a pathologic process of thelumbosacral spine, particularly scoliosis. Data sets werealso excluded when the patient was not exactly posi-tioned along the sagittal axis. The study group wasdivided into four groups according to age: 6–8, 9–11, 12–14 and 15–17 years. The study was cross-sectional andretrospective.MRIAll examinations were obtained using a 1.5-T MRI(Siemens Symphony, Erlangen, Germany). Since theevaluation was performed retrospectively, we selectedT2-weighted sagittal images to measure the vertebralbody diameter (VBD) and dural sac diameter (DSD).Slice thickness was 4 mm in all examinations.MeasurementsAll measurements were performed by one radiologist(C.K.) at a workstation (J-Vision, Tiani Co., Vienna,Austria). The diameters were obtained at each level ofthe lumbar vertebral column (L1–L5) and at the level ofthe ﬁrst sacral vertebral body (S1). Measurements weremade perpendicular to the long axis of the vertebralbody and the dural sac (Fig. 1). The landmarks for themeasurement of VBD were the anterior and posteriorborder at the middle of each vertebral body (at the levelof vessel entry). The DSD was measured as the longestdistance between the posterior border of the vertebralbody and the anterior border of the spinous process. Wecalculated the dural sac ratio (DSR) as the quotient ofDSD to VBD in the diﬀerent age groups. For all datathe mean (±SD) were calculated. A P-value of less than0.05 was considered to indicate a signiﬁcant diﬀerence.ResultsThe mean and standard deviation of the sagittal VBDand DSD of the lumbar spine and the ﬁrst sacral ver-tebral body in children between 6 and 17 years of ageare presented in Tables 1 and 2. There was no signiﬁcantdiﬀerence between the sexes (P>0.05) (Fig. 2). Forfurther analysis, we divided our patients into four ageFig. 1 Example of measurement VBD and DSD in a healthy childTable 1 Sagittal DSD of thelumbar spine in mm from L1 toS1 in children between 6 yearsand 17 years (mean andstandard deviation are given)D diﬀerence between the agegroups*P<0.05Level Age6–8 years D 9–11 years D 12–14 years D 15–17 yearsL1 16.1±1.8 +1.0 17.1±1.3 +0.6 17.7±1.9 )0.1 17.6±1.8L2 15.6±1.5 +0.5 16.1±1.1 +0.6 16.7±1.8 )0.3 16.4±1.8L3 14.5±1.4 +1.1 15.6±1.5 +0.6 16.2±1.7 )0.7 15.5±1.5L4 14.1±1.3 +1.6* 15.7±1.9 +1.0 16.7±1.9 )0.3 16.4±1.6L5 15.1±2.1 +0.8 15.9±1.2 +1.0 16.9±2.4 +0.5 17.4±2.3S1 13.7±1.7 +0.9 14.6±2.0 +0.1 14.7±2.9 +0.3 15.0±2.5420groups 6–8, 9–11, 12–14 and 15–17 years. In all agegroups there is a decrease of DSD from L1 to L3, fol-lowed by a slight increase at the level of L4 to L5, and alarge decrease at the level S1, resulting in the lowestdiameter of the dural sac at S1 (Fig. 3). We observed aslow increase of the DSD (Fig. 3) during growth with adiﬀerence D=+0.8 mm every 3 years up to the age of14 years, which afterwards is reduced to a diﬀerence ofD=+0.03 mm in children older than 14 years (Table 1).Regarding the VBD (Table 2), there is an increasefrom L1 to L3 in all age groups with a peak at L3 or L4.Beyond L5 there is a slight decrease of VBD, followedby a signiﬁcant decrease at S1 (Fig. 3). The growth ofthe vertebral bodies from L1 to S1 is D=+2.4 to+2.7 mm (mean) every 3 years between 6 years and14 years of age (P<0.05 at all levels). In children olderthan 14 years the growth is reduced to a D=+0.75 mmover 3 years (P<0.05 at L1) (Table 2).For this reason the DSR is comparable to the abso-lute values of the diameters of the lumbar spine from L1to S1. The DSR decreases from L1 to L3 (Fig. 4) due tothe increase of VBD and decrease of DSD (Fig. 3). TheDSR at L3 and L4 are at their minimum, while there isan increase at L5 and S1 (Fig. 4). During growth, DSRdecreases by approximately 10% every 3 years (Ta-ble 3).DiscussionThe aim of this study was to establish normal values forthe sagittal diameter of the vertebral body and dural sacof the lumbar spine in children using MRI. In adults,there have been some historical anatomical investiga-tions concerning the normal anatomy of the lumbarvertebral column by Huizinga et al. [8] and Eisenstein[9]. For the paediatric age group, conventional radio-graphic evaluation of the lumbar spinal canal wasundertaken by Hinck et al. [1] and Larsen and Smith [2],while anatomical studies of the lumbar spinal canal wereperformed by Papp et al. [10]. Brandner [11] deﬁnednormal values of the vertebral body during growth usingconventional radiographic techniques. To our knowl-edge our study is the ﬁrst presenting normal values ofthe lumbar vertebral column in the paediatric age groupperformed by MRI.As mentioned before, for adult and paediatric pa-tients [1, 2, 8, 9, 10], our data reﬂect the natural shape ofthe lumbar spine. There is an increase of the VBD fromL1 to L3, with maximum VBD at L3 or L4, a slightdecrease of VBD at L5 and a big decrease of VBD at S1(Fig. 3). In contrast, the DSD reﬂects a mirror-likeimage of VBD with a decrease from L1 to L3 or L4,Table 2 Sagittal VBD of thelumbar spine in mm from L1 toS1 in children between 6 yearsand 18 years (mean andstandard deviation are given)D diﬀerence between the agegroups*P<0.05Level Age6–8 years D 9–11 years D 12–14 years D 15–17 yearsL1 21.6±2.2 +2.3* 23.9±2.9 +2.3* 26.2±2.5 +1.7* 27.9±2.8L2 22.6±2.2 +3.0* 25.6±3.1 +2.2* 27.8±3.0 +1.1 28.9±3.1L3 23.4±2.1 +2.7* 26.1±2.9 +2.8* 28.9±2.9 +0.8 29.7±3.0L4 23.8±1.9 +2.5* 26.3±2.5 +2.5* 28.8±3.2 +0.9 29.7±3.1L5 22.4±2.2 +3.4* 25.8± 2.0 +2.4* 28.2±3.2 +0.3 28.5±3.0S1 17.4±1.4 +2.5* 19.9±2.5 +2.1* 22.0±3.0 )0.3 21.7±2.5Fig. 2 Sagittal DSD and VBDof the lumbar spine from L1 toS1 in children between 6 yearsand 17 years, mean and stan-dard deviation are given. Nosigniﬁcant diﬀerence betweenthe sexes could be detected421followed by a slight increase at L5, that does not reachthe highest values of L1 (Fig. 3). At S1 there is a paralleldecrease of VBD and DSD to the lowest absolute values(Fig. 3).Our data for DSD are comparable to those of Larsenand Smith [2] and Papp et al. [10] with a diﬀerence ofapproximately 1 mm between L1 and L5 (Fig. 5).Compared to the spinal canal sagittal diameters pub-lished by Larsen and Smith, the DSD in our series werelower in the 6–8-year age group, increasing in the agegroups 9–11 years and 12–14 years (Fig. 3). Therefore,we conclude that with increasing age there is a slightincrease in DSD. In contrast, Papp et al. [10] concludedthat mid-sagittal growth of the lumbar spinal canal iscomplete at L1–L5 by 4 years of age. The values for thelumbar spinal canal found by Hinck et al. [1] were higherin all age groups and at all levels (Fig. 5). The reason forthe diﬀerences between the data of Hinck et al. [1] andour data for the DSD may be attributed to errors causedby magniﬁcation, as discussed by Larsen et al. [2]. MRIis not aﬀected by the problem of magniﬁcation.VBD increases signiﬁcantly with increasing age(P<0.05). Brandner [11] also described this age-relatedgrowth of VBD [11], although the absolute values for L1were higher than ours. Therefore, DSR decreases withincreasing age, because VBD increases more rapidlythan DSD (Fig. 4).The upper limit of DSR may serve to deﬁne patho-logical entities such as dural ectasia in patients withMarfan syndrome (Fig. 1). Compared to the cut oﬀvalues for normal DSRs published by Oosterhof et al.[12] our DSR values in the diﬀerent age groups werehigher (Table 3). Therefore, the incidence of duralectasia in children with Marfan syndrome may beoverestimated using the cut-oﬀ values deﬁned for adultpatients [12]. Further studies are needed to compareDSD and DSR values of patients with Marfan’s syn-drome with normal subjects.Fig. 3 Sagittal DSD and sagit-tal VBD of the lumbar spinefrom L1 to S1 calculated fordiﬀerent age groups, mean andstandard deviation are givenFig. 4 Ratio of dural sacdiameter to vertebral bodydiameter (DSR) of the lumbarspine from L1 to S1 calculatedfor diﬀerent age groups, meanand standard deviation aregiven422ConclusionsNormal values for the sagittal diameter of the verte-bral body and dural sac in the lumbosacral spine, andthe DSR from L1 to S1, as measured by MRI, havebeen deﬁned in healthy children between 6 years and17 years of age. The data reﬂect the natural shape ofthe vertebral column with an increase of the vertebralbody dimensions from L1 to L3 with a maximum atL3 or L4, and a decrease at L5 and S1. Dural sacdimensions mirror the vertebral body dimensions.Table 3 DSR of the lumbarspine in mm from L1 to S1 inchildren between 6 years and17 years (mean and standarddeviation are given)Level Age6–8 years 9–11 years 12–14 years 15–17 years Adults (publishedby Oosterhof et al. [12])L1 0.75±0.10 0.72±0.10 0.68±0.09 0.64±0.09 0.48±0.08L2 0.69±0.08 0.64±0.08 0.61±0.11 0.58±0.10 0.40±0.08L3 0.62±0.08 0.61±0.11 0.57±0.10 0.53±0.08 0.35±0.06L4 0.62±0.07 0.61±0.12 0.57±0.11 0.53±0.08 0.34±0.08L5 0.68±0.13 0.62±0.06 0.61±0.11 0.62±0.10 0.32±0.08S1 0.79±0.11 0.75±0.14 0.68±0.15 0.72±0.14 0.35±0.11Fig. 5 Comparison of normalvalues for lumbar spinal canaldiameter respectively. DSDpublished by diﬀerent authorsReferences1. Hinck VC, Hopkins CE, Clark WM(1965) Sagittal diameter of the lumbarspinal canal in children and adults. AJR96:929–9372. Larsen JK, Smith D (1981) The lumbarspinal canal in children. Part 1: thesagittal diameter. Eur J Radiol 1:163–1703. Boltshauser E, Hoare RD (1976)Radiographic measurements of thenormal spinal cord in childhood. Neu-roradiology 10:235–2374. Fattori R, Nienaber CA, Descovich Bet al (1999) Importance of dural ectasiain phenotypic assessment of Marfan’ssyndrome. Lancet 354:910–9135. Jamjoom ZA, Malabarey T, KolawoleTM et al (1990) Lumbosacral duralanomalies in von Recklinghausen neu-roﬁbromatosis. Acta Neurochir105:140–1466. Schonauer C, Tessitore E, Frascadore Let al (2000) Lumbosacral dural ectasiain type 1 neuroﬁbromatosis. Report oftwo cases. J Neurosurg Sci 44:165–1687. Katz SG, Grunebaum M, Strand RD(1978) Thoracic and lumbar dural ec-tasia in a two-year-old boy. PediatrRadiol 6:238–2404238. Huizinga J, Heiden JA, Vinken PJ(1951) The human lumbar vertebralcanal. A biometric study. P K NedAkad Wetensc 55:22–339. Eisenstein S (1977) The morphometryof pathological anatomy of the lumbarspine in South African negroes andcaucasoids with speciﬁc reference tospinal stenosis. J Bone Joint Surg Br59:173–18010. Papp T, Porter RW, Aspden RM (1994)The growth of the lumbar vertebral ca-nal. Spine 19:2770–277311. Brandner ME (1970) Normal values ofthe vertebral body and intervertebraldisk index during growth. Am JRoentgenol Radium Ther Nucl Med110:618–62712. Oosterhof T, Groenink M, HulsmansFJ et al (2001) Quantitative assessmentof dural ectasia as a marker for Marfansyndrome. Radiology 220:514–518424

Normal values of the sagittal diameter of the lumbar spine (vertebral body and dural sac) in children measured by MRI

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Normal values of the sagittal diameter of the lumbar spine (vertebral body and dural sac) in children measured by MRI

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