SPINE Volume 41, Number 16, pp E987–E994 ß 2016 Wolters Kluwer Health, Inc. All rights reserved DIAGNOSTICS Type II Modic Changes May not Always Represent Fat Degeneration A Study Using MR Fat Suppression Sequence Zhiyun Feng, MD,Ã Yuanhao Liu, MD,Ã Wei Wei,y Shengping Hu, MD,y and Yue Wang, PhDÃ (24.7%) type II MCs was suppressed on FS images, that of 113 Study Design. A radiological study of type II Modic changes (75.3%) was not suppressed. The discs adjacent to type II MCs (MCs). had lower signal intensity (0.13 Æ 0.003 vs.0.14Æ 0.004, Objectives. The aim of this study was to determine the P < 0.001), lesser disc height (9.73 Æ 1.97 vs.11.07Æ 1.99, characteristics of type II MCs on fat suppression (FS) magnetic P < 0.001) and greater bulging area (80.0 Æ 31.4 vs. 61.3 Æ 27.5 resonance (MR) images and its association with radiological disc for anterior bulging, 33.72 Æ 21.24 vs. 27.93 Æ 12.79 for degeneration. Summary of Background Data. Type II MCs are common posterior bulging, and 113.7 Æ 39.9 vs. 89.2 Æ 35.2 for total < endplate signal changes on MR images. On the basis of limited bulging, P 0.05) than normal controls. Type II MCs that were histological samples, type II MCs are thought to be stable fat not suppressed on FS image were associated with greater age < degeneration. FS technique on MR, which can quantify fat [odds ratio (OR) ¼ 1.11, P 0.001], lower height (OR ¼ 0.94, < < content, may be an alternative to explore the pathology of MCs. P 0.05), and greater posterior bulging (OR ¼ 1.05, P 0.001) at To date, however, the characteristics of type II MCs on FS the adjacent disc. Conclusion. Signal of most type II MCs was not suppressed on sequence have not been studied. Methods. Lumbar MR images conducted in a single hospital FS MR images, suggesting that there are ongoing complicated during a defined period were reviewed to include those with pathologies. Type II MCs may not merely represent fat replace- type II MCs and FS images. On FS images, signal status of type ment. Key words: disc degeneration, fat suppression, lumbar spine, II MCs was visually classified as suppressed or not-suppressed. magnetic resonance imaging, Modic changes, quantitative image Signal intensity of vertebral regions with and without MCs was analysis. measured quantitatively on T2-weighted (T2W) and FS images to Level of Evidence: 3 calculate fat content index and validate the visual classification. Spine 2016;41:E987–E994 Using image analysis program Osirix, MCs size and adjacent disc degeneration were measured quantitatively. Paired t-tests and logistic regressions were used to determine the associations studied. odic changes (MCs), or endplate signal changes, Results. Sixty-four lumbar MRIs were included and 150 end- are common findings on lumbar spine magnetic plates with type II MCs were studied. Although signal of 37 M resonance (MR) images. The prevalence rates of MCs reportedly vary from 19% to 59%, depending on study samples.1 Traditionally, MCs are classified into three types. From the ÃSpine Lab, Department of Orthopedic Surgery, The First Affiliated Type I MCs present decreased signal intensity on T1- Hospital, College of Medicine, Zhejiang University, Hangzhou, China; and yDepartment of Orthopedic Surgery, Integrated Chinese and Western Medi- weighted (T1W) images and increased signal intensity on cine Hospital of Zhejiang Province, Hangzhou, China. T2-weighted (T2W) images. Type II MCs reflect increased Acknowledgment date: September 14, 2015. First revision date: December signal intensity on both T1W and T2W images and type III 12, 2015. Acceptance date: January 22, 2016. MCs display decreased signal intensity on both T1W and The manuscript submitted does not contain information about medical T2W images.2 While type II MCs are the most common device(s)/drug(s). endplate signal changes, type III MCs are rare. National Natural Science Foundation of China (NSFC, No. 81371995) and AO Spine 2015 China Research Grant [AOSCN (R) 2015-03] funds were Although MCs were intensively studied for decades, received in support of this work. much remained unclear. The association between MCs No relevant financial activities outside the submitted work. and back pain, for example, remains controversial. Address correspondence and reprint requests to Dr. Yue Wang, PhD, Although many researchers reported that both type I and Building 3-2, 79#, Qingchun Road, Hangzhou 310003, China. II MCs were associated with back pain,3,4 some specified E-mail: [email protected] that it was type I MCs, but not type II MCs, that was 5 DOI: 10.1097/BRS.0000000000001526 associated with back pain. The association between MCs Spine www.spinejournal.com E987 Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. DIAGNOSTICS Type II Modic Changes Feng et al and back pain, however, was not observed in some clinical MATERIALS AND METHODS studies.6–8 On the contrary, although it is generally accepted that MCs are associated with disc degeneration, quantitative Samples data supporting this relationship are insufficient. Image samples of this study were collected at the Integrated A limited understanding of clinical relevance of MCs is Chinese and Western Medicine Hospital of Zhejiang Prov- due, at least in part, to the poor knowledge of MCs path- ince, China. Lumbar spine imaging conducted here routinely ology. According to an early report, type I MCs were includes T1W, T2W, and FS sequence. All lumbar spine MR characterized by inflammatory reactions and vascular gran- imaging performed from April 1 to September 31 of 2014 ulation formation, and fatty degeneration was a prominent were reviewed by an orthopedic surgeon (ZYF) for the pathological finding for type II MCs.9 Surprisingly, how- presence of any type of MCs. MRIs were excluded if there ever, this widely spread concept was based on merely six were suspected metastatic lesions, ankylosing spondylitis, histological samples.9 The pathological entities of MCs, lumbar spine infections, scoliosis, fresh vertebral fractures, therefore, deserve further investigation. or lumbar instrumentations. If MCs are present, MRIs were Given the scarcity of histological samples nowadays, a downloaded in DICOM format for further evaluation. Two radiological study may be a reasonable alternative to authors (SPH and YHL) further reviewed all selected lumbar further understand the pathology for MCs. Fat suppression spine MRIs together to evaluate specific type of MCs. MCs (FS) techniques are commonly used in the differential were classified as type I (hypo-intensity on T1W images and diagnosis for spine disorders. On FS sequence, signal hyper-intensity on T2W images), type II (hyper-intensity on contribution from fat or fat-related components is sup- both T1W and T2W images), type III (hypo-intensity on pressed and thus displays decreased signal on MR images. both T1W and T2W images), and mixed type of MCs Recently, FS techniques were used to quantify fat content (mixed I/II and mixed II/III).2,13 in liver,10 subcutaneous tissue,11 and bones.12 Although fat As the focus of the current study was type II MCs, only may be an important component of type II MCs, the lumbar MRIs with type II MCs were included for further characteristics of type II MCs on FS sequence have not assessment and type I, type III, and mixed MCs were all been studied yet. excluded. In MCs evaluation, we excluded small signal In clinical practice, we have noticed an interesting changes on vertebral body corners and those endplate signal phenomenon that type II MCs had different presentations changes that presented on less than three sagittal slices to on FS images. Although signal of some type II MCs was minimize measurement errors.14 As only patients’ images suppressed on FS images, as compared with that of adjacent were reviewed in the present study, ethic permission was vertebral marrow without MCs (Figure 1 A-C), in many waived by the authors’ institutional review boards. cases, signal on FS images was not suppressed (Figure 1 D-F). We postulated that the divergent presentations of type II MR Imaging Technique MCs on FS images may be due to varied pathologies under- MR imaging was performed using a 3.0 Tesla scanner lying, which may have different pathological effects on the (Philips Medical Systems; Best, The Netherlands). Sagittal adjacent intervertebral disc. The purposes of the current T2W images were acquired using a fast spin-echo sequence study, therefore, are to characterize type II MCs on FS with a repetition time (TR) of 4000 ms, echo time (TE) of sequence and further to determine the association between 118 ms, echo train length of 27, and the number of acqui- FS status of type II MCs and adjacent disc degeneration. sitions of 4. The matrix size was 448 Â 224, field of view Figure 1. Different presentations of type II MCs on fat suppression (FS) sequence. Type II MCs in a 33-year-old woman (A,B). Signal of the type II MCs region was suppressed on FS image, as compared with adjacent normal vertebral region without MCs (C). Type II MCs in a 54-year-old woman (D,E). On FS image, signal of region with type II MCs was not suppressed, as refer to the adjacent vertebral region without MCs (F). FS indicates fat suppression; T1W, T1-weighted; T2W, T2-weighted. E988 www.spinejournal.com August 2016 Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. DIAGNOSTICS Type II Modic Changes Feng et al 28 Â 28 cm, slice thickness 4 mm, and intersection gap Due to the heterogeneity of signal on MR imaging, it may 1 mm.