Evaluation of Schmorl's nodes using F-18 FDG PET/CT

Author's personal copy

Evaluation of Schmorl's nodes using F-18 FDG PET/CT

C-Y. Li

n

，

H.-Y.

Chen

，

H.

寸

.

Oing

，

Y.-I<.

Chen

，

C-H. I<

ao

*

a Department of Nuclear Medicin巴• Show Chwan Memoriα1 Hospital Changhuα• Taiwan

b Graduate School of Biotechnology. Hungkuang Universi紗TaichunJ己，α1ìlwan c Department of Radiology Chinα Medical University Hospitα1. Taichung. Taiwαn

dDepa前ment of Medical Imaging and Radiological Sciences I-Shou Universi旬 Kaohsiung，Taiwan

e Department of Nuclear Medicine and PEr Center Shin Kong Wu Ho-Su Memorial Hospital and School of Medicine，Fu Jen Catholic University Taipei Taiwan

f Department of Nuclear Medicine and PET Center China Medical University Hospital Taichung，Taiwan

g Graduate Insti組te of Clinical Medicine Science College of Medici ，China Medical Univers 旬i

Taichung，Taiwan

ARTICLE INFOR 恥iATION AIM: To evaluate the image findings of Schmorl's nodes on combined 2-[18F ]-fluoro-2-deoxY-D-glucose positron-emission tomography/computed tomography (即G PET/CT)

MATERIALS AND METHODS: Twelve patients who were diagnosed with Schmorl's nodes and had undergone magnetic resonance imaging (MRI) and FDG PET/CT were retrospectively recruited for this study. The period between the MRI and the FDG PET/CT examinations was within 1 week. The demographic data and c1inical history were reviewed. The relationship between MRI findings and the values of maximum standardized uptake value (SLNmax) on FDG PET/CT was analysed.

RESULTS: The mean values of early and delayed SLNmax of Schmorl's nodes without MRI enhancement were 1.14 土 0.28 and 1.09 土 0.32. The m凹 n values of early and delayed SLNmax of SchmorI's nodes with MRI enhancement were 1.73 士 0.49 and 1.75 士 0.54. There were significant differences in the early and delayed SUVmax between SchmorI's nodes with and

without perifocal enhancement on MRI with Wilcoxon's rank-sum test (p = 0.012; P = 0.006). There was a trend of positive correlation although not statisticaIly signifi日吭， between delayed SLNmax on FDG PET/CT and age in SchmorI's nodes with Sp臼 rman's rank correlation

(B = 0.86，P = 0.056).

CONCLUSIONS: Schmorl's nodes demonstrated low to moderate uptake on FDG PET/CT images. Schmorl's nodes with perifocaI enhancement on MRI result in higher FDG uptake. The possibility of false positives caused by Schmorl's nodes should be considered when interpreting FDG P盯/CT images of bone metastases，自peciaIly in the aging population

2012 The Royal CoIIege of Radiologists. PubIished by Elsevier Ltd. AIl rights reserved.

Introduction

* Guarantor and correspondent: C.-H. K泊， Department of

Nuclear

Schmorl first described cartilaginous nodal hemiation of the disc into the adjacent vertebral body in 1927.12 The

reported incidence of Schmorl's nodes ranges from 2-76%.

Medicine and PET Center China Medical University Hospital No.

，2 Yuh-Der The pathogenesis ofthis node is uncertain. Schmorl's nodes

Road ，Taichung 404，Taiwan. Tel.: +886 4 22052121x7412; fax:

+886 4 22336174.

E-mail address: d1004 0 @ ma i l . cmuh . o rg.tw (C.-H. Kao). h Both authors contributed equally to this work

are thought to be traumatic lesions caused by compressive vertebral loads and development defects in the vertebral endplates. Most underlying conditions are non-neoplastic，

凹的 92601$ see front matter @ 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved doi:10.1016Ij .crad.2012.04.006

，

士。

but occasionally they occur in metastatic carcinoma

patients.1.3-7 intravenously via hand injected. The mean time interval _{between injection and scan acquisition was approximately} 2-[18F]-f1uoro-2-deoxY-D-glucose (FDG) is the most 3 min. All 12 patients were subsequently imaged using commonly used radiopharmaceutical for positron-emission

tomography (PET) studies in oncology. The tracer is a substrate of energy metabolism; therefore an increased FDG uptake is not limited to malignant tissues.8一₁₀

One article reported that Schmorl's nodes may cause increased FDG activity.11 The aim of the present study was to evaluate the image findings of Schmorl's nodes on magnetic resonance imaging (MRI) and the value of SUV max on combined FDG PET/computed tomography (G).

Materials and methods

Between January 2009 and December 2010，12 patients

a sagittal and 且ial SE T1-weighted sequence (400-650 ms TR/10-14 ms TE) with fat saturation. For all sagittal sequences the section thickness was 4 mm skip 1 mm， 25 cm FOV，number of excitations (NEX) 2 -4 and matrix

512 x 256; for axial scans the slice thickness was 4 mm， skip 1 mm，25 cm FOV NEX 2-4，and matrix 256 x 256.

Presence and enhancement of Schmorl's nodes were analysed independently by two musculoskeletal radiolo gists. Only circumscribed defects 3 mm or larger were considered to be Schmorl's nodes. Cupid bow endplates with regular bowing of the posterior third of the vertebral endplate and small erosive defects of the endplates in degenerated segments were not considered Schmorl's

2 (6 men and 6 women; mean age 60.42 土 12.12

years)

nodes. 15Enhancement of Schmorl's nodes was quantified diagnosed with Schmorl's nodes who had undergone

both

MRI and FDG PET/G at the China Medical University Hospital. were retrospectively recruited for this study. The time interval between the MRI and the FDG PET examinations was within 1 week.This study was approved

by the hospital ethics committee (DMR-99-IRB-010). The demographic data clinical history，image findings on MRI

and values of early and delayed maximal standardized uptake value (SUVmax) on FDG PET/CT were reviewed.The relationship between MRI findings and the values of early and delayed SUVmax on FDG PET/G was analysed.

FDG PETjCT imαging protocol αnd datααnαlysis

All patients were asked to fast for at least 4 h before FDG PETIG imaging. Imaging was performed with a PETICT

by measuring signal intensity in appropriate regions of interest on T1-weighted MRI images before and after administration of contrast medium. Enhancement within the Schmorl's nodes was recorded as well as in the adjacent vertebral body. Enhancement within the vertebral body consisted of a thick rim of enhancement surrounding the invaginated or extruded disc material with homogeneous enhancement in the disc material itself as well as in the parent intervertebral disc. On T2-weighted SE and STIR images high-signal-intensity areas in the adjacent bone marrow (perifocal oedema) were recorded.

St，α tisticα1 anαlysis

The average values of age and earlyand delayed SUVmax on FDG PETκT were expressed as mean 土 standard devia

machine (Discovery STE GE Medical Systems，Milwaukee， tion. The mean values of early and delayed SUVmax of

叭月， USA). Whole-body FDG PET/G images were acquired approximately 45 min after intravenous injection of370 MBq

(10 mCi) FDG. We obtained delayed FDG PET/G images approximately 70 min after FDG i吋ection

戶一

were acquired after CT at 2 min per field ofview (FOV) in the three-dimensional acquisition mode. The G images were reconstructed onto a 512 x 512 matrix with a section thidmess of 3.75 mm，reconstructed onto a 128 x 128 matrix and converted into 511 - keV-equivalent attenuation

factors for attenuation correction of the corresponding PET images. The SUVmax of Schmorl's nodules on early and delayed FDG PET/G images were recorded.

MRI and inte中間的tion

All examinations were performed on a 1.5 T unit (Signa;

General Electric Medical Systems

Milwaukee ， WI ， USA) using a spine coil. Pulse sequences included spin-echo (SE) T1-weighted sequences [400-650 ms repetition time(TR)1

9-13 ms echo time (TE)] on sagittal plane short tau inversion recovery (STIR) sequence on sagittal plane and T2-weighted fast SE sequences (2500-6000 ms TRI 70-100 ms TE ) on sagittal and 且ial planes. All patients

Schmorl's nodes on FDG PET/G with and without back pain were compared using Wilcoxon's rank-sum test.The mean values of early and delayed SUVmax of Schmorl's nodes on FDG PET/G with and without perifocal enhancement on MRI were compared using Wilcoxon's rank-sum test. The relationship between age and SUVmax on FDG PET/CT in Schmorl's nodes was analysed using Spearman's rank correlation. All analyses were conducted by STATA 11.0 using a 0.05 level of significance.

Results

Twelve Schmorl's nodes were examined in the present study. The Schmorl's nodes on FDG PET/CT showed mild to moderate FDG activity (Figs 1 and 2 ). The mean values of early and delayed SUVmax in all Schmorl's nodes were 1.48 土 0.51 (range 0.70-2.80) and 1.48 .56 (range

0.54-2.77). Seven out of 12 patients complained of bad< pain. Seven out of 12 Schmorl's nodes revealed perifocal enhancement on MRI (Table 1). Five patients with peri-focal enhancement on MRI complained of back pain. No signifi cant difference in early or delayed SUVmax on FDG PET/G was found between Schmorl's nodes with and without bad<

were administered the same contrast medium (Omniscan ， pain. The mean values of early a nd delayed SUVmax of

Figure 1 A 50-year-old man diagnosed with Schmorl's nodes at L4level with low FDG activity on FDG PET PET/cr (arrows) and corresponding MRI (the most right column).

1.14 土 0.28 and 1.09 土 0.32. The mean values of early and delayed SUVmax of Schmorl's nodes with MRI

enhance ment were 1.73 ::l: 0.49 and 1.75 ::l: 0.54. Significant differ

ences were found in the early and delayed SUVmax between Schmorl's nodes with and without perifocal enhancement on MRI using Wilcoxon's rank-sum te鈍， respectively (p

=

=

FDG PETjCT and age of the patient with Schmorl's nodes by Spearman's correlation (B 三 0.86，P

=

this trend was not statistically significant.

Discussion

Schmorl's nodes are vertical disc hemiations through areas of weakness in the endplate， with male

-z3456789111

(+) (-) 1.40 1.49 1.37 1.52 (+)(+) (-) 1.04 1.10 (一) (+) 1.25 1.37 (一) (+) 1.35 1.41 (+) (一) 1.63 1.40 (+) (+) 1.68 1.58 (+) (+) 1.77 2.23 (+) (+) 1.25 1.21 (一)

。

between age and delayed SUVmax on FDG PET/G was also Demographic informa-Anuo。只UQJ寸，結可弓，但QJPb?Jnu tion，mean values of early and delayed

maximum

standardized uptake value (SUVmax) on 2-11_{BF]-fluoro-2-deoxy-o-glucose}

positron-emission tomographyfcomputed tomography (FDG PETfCT)

found which may support the relationship of Schmorl's nodes with degenerative disc disease. However the sample size in this study is relatively small; therefore the inference Patient Gender Age Back

pam Early SUVmaxon Delayed SUVmax on Perifocal

enhancement of this study is limited._{In conclusion，Schmorl's nodes demonstrated low to} FDG PETf 口 FDG P凹

叮

onM則

moderate FDG uptake on FDG PET/G images. Schmorl's (-) (一) (+) 1.44 0.70 2.80 1.24 .54 2.77 (-) (一) (+)

nodes with perifocal enhancement on MRI resulted in higher FDG uptake. The possibility of false positives caused by Schmorl's nodes should be considered when interpreting FDG PET/CT images of bone metastases especially in the aging population.

Acknowledgements

F，female; M，male; (-) ，negative;

(+)，positive.

predominance. Schmorl's nodes are fairly common in the aging spine with minor degeneration but they are also seen in younger spines. Although Schmorl's can be detected by radiography they are more often seen on MRI. Schmorl's nodes on MRI typically demonstrate a focal extension on the nucleus pulposus into the vertebral body. They may or may not be symptomatic. Most chronic lesions are asymp

tomatic. At the acute stage Schmorl's nodes can be painful， probably because of fracture of the endplate戶一18 Research has shown that the incidence of lower bad< pain in high

school rugby players caused by Schmorl's nodes was

14.1 %1.

9

PET using FDG has been well established as a non invasive diagnostic tool for the detection of a variety of malignancies and non-malignancies. However only Chen et al.ll _{reported an increased FDG activity caused} by

Schmorl's nodes.

In the present study low to moderate FDG activity was

demonstrated in the 12 Schmorl's nodes. Schmorl's nodes

with perifocal enhancement on MRI had significantly

higher values of early and delayed SUVmax on FDG PET/CT.

Schmorl's nodes are protrusions of disc materials into the

surface of the vertebral body which may contact the ma汀ow of the vertebra and lead to inflammation resulting in increased FDG activity. A trend of positive correlation

This study was supported by grants (DMR-101-061 and DMR-101-080) from our hospital，the Taiwan Department of Health Clinical Trial and Research Center of Excellence (DOH101-TD-B-111-004)，and the Taiwan Department of Health Cancer Research Center for Excellence (DOH101-TD

C-111-005).

References

1. Wu HT，Morrison WB，Schweitzer ME. Edematous Schmorl's nodes on thoracolumbar MR imaging: characteristic patterns and changes over time.Skelet ，口1 Radiol 2006;35:212-9.

2. Dietz GW Christensen EE. Normal“Cupid's bow" contour of the lower lumbar vertebrae.Radiology 1976;121:577-9.

3. Stäbler A，Bellan M，Weiss M，et aL MR imaging of enhancing intra

osseous disk herniation (Schmorl's nodes). AJR AmJ Roentgenol 1997;

168:933-8.

4. Lipson 勻，Fox DA，SosmanJL Symptomatic intravertebral disc herniation

(Schmorl's node) in the cervical spine. Ann Rheum Dis 1985;44:857-9

5. Tsuji H，Yoshioka T，Sainoh H. Developmental balloon disc of the lumbar spine in healthy subjects. Spine (Phila Pa 1976) 1985;10:907 -11.

6. Pfìrrmann CW，Resnick D. Schmorl nodes of the thoracic and lumbar spine: radiographic-pathologic study of

prevalence，characterization，

and correlation with degenerative changes of 1650 spinal levels in 100

cadavers. Radiology 2001;219:368-74.

7. Resnick D ， Niwayama G. lntravertebral disk herniations: cartilaginous

(Schmorl'的 nodes. Radiology 1978;126:57 -65.

8. Cook GJ Wegner EA，Fogelman L PitfaIls and artifacts in 1日FDG PET

and

PETJCT oncologic imaging. Semin Nucl Med 2004;34:122-33

9. Cook GJ Maisey MN，Fogelman L Normal variants，artefacts and inter

pretative pitfalls in PET imaging with 18-fluoro-2-deoxyglucose and

carbon-11 methionine. EurJ Nucl Med 1999;26:1363-78

10. Shreve PD Anzai Y， 叭rahl RL Pitfalls in oncologic diagnosis with

FDG

PET imaging: physiologic and benign variants. RadioGmphics 1999;

19:61-77.

11. Chen YK Chen HY ， Kao CH.Schmorl's node may cause an increased FDG

activity. Clin Nucl Med 2011;36:494-5

12. Conrad GR，Sinha P. Narrow time-window dual-point 18F-FDG PET for the diagnosis of thoracic malignancy. Nud Med Commun 2003; 且:1129-37.

13. SchiIIaci 0，Travascio L ， Bolacchi F et aL Accuracy of early and delayed

FDG PET-CT and of contrast-enhanced CT in the evaluation of lung nodules: a preliminary study on 30 patients. Radiol Med 2009;

2008;29:425-30.

15. Ramirez H，Navarro JE，Bennet WF. Cupid's bow

conto ur of

the lumbar

16. park P，Tran NK，Gala VC et al. The radiographic evolution of a Schmorl's

node. Br] Neurosurg 2007;21:224-7

17. Peng B Wu W，Hou S，et al. The pathogenesis ofSchmorl's nodes.]Bone

]oint Surg Br 2003;85:879-82.

magnetic resonance imaging with histologicaI fìndings. Spine (Phila Pa 1976) 2003;28:E503-5.

的 Iwamoto J Abe H，Tsukimura Y et al. Relationship between

radiographic

abnormalities of lumbar spine and incidence of low back pain in high 18.

Yamaguchi， T

Suzuki S，Ishiiwa H et al. Schmorl's node developing in the

schooI rugby players: a prospective study. Scand] Med Sci Spo 月s 2005;