Clinical StudyInterreader and intermodality reliability of standard anteroposterior radiograph and magnetic resonance imaging in detection and classification of lumbosacral transitional vertebra
Introduction
A lumbosacral transitional vertebra (LSTV) was initially defined as the last lumbar vertebra with an additional connection between the transverse process to the sacrum [1]. Castellvi et al. [2] suggested a classification of LSTV in 1984. The classification, widely used today, is based on the assessment of a unilateral or bilateral hypertrophied transverse process of the last lumbar vertebra and its relationship to the sacrum (no connection, articulation, or osseous bridging) (Fig. 1). This classification was introduced using conventional radiographs—not with standard anteroposterior (AP) lumbar spine radiographs, but a 30° angled AP view of the lumbosacral joint (Ferguson view) with the aim to decrease the radiographic overlap effect of the transverse process of the last lumbar vertebra on the sacrum [2]. A high interreader reliability in LSTV classification has been reported (kappa=0.77–1) [3], [4] with the Ferguson view. However, Ferguson view radiographs are not routinely performed as part of the standard radiographic assessment of the lumbar spine, which typically includes standing AP and lateral radiographs. The interreader reliability and accuracy for the standard AP radiograph for detection and classification of different LSTV types is not known. Coronal magnetic resonance imaging (MRI) scans are anecdotally accepted as highly reliable in detection and classification of LSTV, but to the best knowledge of the authors, there are no reports on interreader reliability of coronal MRI to classify LSTV.
The first hypothesis of this study was that standard AP radiograph of the lumbar spine was unable to provide a sufficient interreader reliability and accuracy in detection and classification of LSTV. The second hypothesis was that coronal MRI was highly reliable in classification of LSTV.
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Subjects
After institutional review board approval, 93 subjects with LSTV (type 2 or higher) (mean age±standard deviation: 56.7±16.4 years) from a database of 770 patients diagnosed with LSTV, retrieved from a picture archiving and communication system search, were randomly added and defined as the case group. Sixty-two subjects (58.2±16.4 years of age) without a connection between their transverse process of the last lumbar vertebra and the sacrum were added as the control group (imaged between
Detection
The interreader reliability for the detection of a connection between the transverse process of the last lumbar vertebral body to the sacrum was moderate (k=0.53) in standard AP radiograph, but almost perfect (k=0.93) with coronal MRI.
Classification
The interreader reliability for classification of LSTV was at best fair (wk=0.39) in standard AP radiograph, but very good (k=0.83) with coronal MRI (Fig. 4).
One hundred and twenty-nine of 155 subjects were classified correctly by both readers using MRI. However,
Discussion
The purpose of this investigation was to determine the reliability and accuracy of standard AP radiographs of the lumbar spine to detect and classify LSTV. In addition, the reliability of coronal MRI was assessed. Our data suggest that standard AP radiographs are insufficient to detect or classify LSTV because the interreader reliability was at best moderate (k=0.53) to detect and only fair (wk=0.39) to classify an LSTV. Second, the accuracy for standard AP radiographs, using MRI as the gold
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2017, World NeurosurgeryCitation Excerpt :LSTV with articulation of some degree is defined as either sacralization of the fifth lumbar segment or lumbarization of S1.9,13 Previous studies have found that the presence of LSTV leads to earlier occurrence and more severe disc degeneration; this is especially true in younger individuals.11,13-15 An increased prevalence of disc protrusion or extrusion in the disc above the transitional L5 vertebra has been found in patients with LBP.16-19
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2015, European Journal of RadiologyCitation Excerpt :The facet joints are best assessed on axial images for the presence of arthrosis, synovitis and indirectly for segmental instability. The coronal images, if performed, are particularly helpful for identification and classification of lumbosacral transitional vertebra [16]. Coronal images also help to get an overview of the extent of scoliosis, if present and in detection of extraforaminal herniations.
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2015, Spine JournalCitation Excerpt :This group was divided into three subgroups base on the Castellvi classification [6]—type 2, articulated connection (N=46); type 3, osseous connection (N=32); and type 4, both osseous and articulated connection (N=14)—by one radiologist using MRI images. A previously published study demonstrated a very good interreader agreement in classification of LSTV using MRI [12]. Ninety-four subjects without a lumbosacral transitional vertebra, in whom a lumbar spine magnetic resonance imaging (MRI) had been performed between June 2012 and November 2012 (41 men, 53 women; mean age, 51±16 years) were added randomly and are referred to as the control group.
FDA device/drug status: Not applicable.
Author disclosures: NAF-A: Grants: Individual funding of Swiss National Foundation (PBYHP3_143674) (D). BL: Nothing to disclose. RJH: Nothing to disclose. MF: Nothing to disclose.
The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.
Supported by the departmental fund of the MRI Department, Hospital for Special Surgery, New York, NY, USA and individual funding of Swiss National Foundation (NAF-A PBZHP3_143674).