Standing MRI exaggerates lumbar stenosis but does not improve patient symptom correlation

Transcription

1 Standing MRI exaggerates lumbar stenosis but does not improve patient symptom correlation SP15 Ryan K.L.Lee, James F Griffith, Yvonne Lau, Defeng Wang, Shi Lin, Alex W.H. Ng, Esther H.Y. Hung leekalok2909@yahoo.com.hk Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, The Chinese University Department of Diagnostic Radiology and Organ Imaging,of TheHong ChineseKong University of Hong Kong

2 Introduction Lumbar spinal stenosis often leads to neurogenic claudication lower back and sciatica-type pain aggravated by standing, walking or spinal extension in upright position Conventional MRI in supine (recumbent) position widely used Nearly all studies have shown only modest correlation between supine MR finding and patient symptoms

3 Introduction Standing MRI increases lumbar lordosis Due to a gravity effect on upper body and alteration in core (paraspinal and abdominopelvic) muscle action Standing MRI can accentuate dynamic component of spinal morphology Such as intervertebral disc bulging, ligamentum flavum infolding and decrease in dural sac crosssectional area

4 Aim To investigate whether morphological changes with standing MRI improves correlation with patient symptomatology

5 Methods : patients Prospective study From January 2010 to June 2013 Inclusion : Patients with symptoms of lumbar spinal stenosis (neurogenic claudication comprising leg pain and/or numbness) Diagnosis established by an experienced spine surgeon, based on symptoms, neurological examination, radiographs and MRI Exclusion : previous lumbar spine surgery, spinal anomaly, scoliosis, spinal trauma, tumor, infection, polyneuropathy Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong and arterial insufficiency

6 Clinical Assessment Clinical parameters: Age Sex Walking time (minutes) Walking distance (meters) Duration of symptoms (years) Visual Analogue Score (VAS) of lumbar and leg pain (0-10) Oswestry Disability Index (ODI) Short Form (SF)-12

7 MRI assessment All MRIs performed on a 0.25-Tesla system (G-scan, Esaote, Genoa, Italy) Imaging in both supine and standing positions Sequences: - axial T2-weighted GE 3D (TE: 10ms, TR: 5ms, flap angle: 70, field of view: 210x210mm, matrix 512x512, reconstructed slice thickness 4.0mm) - sagittal T2-weighted TSE (TE: 100ms, TR: 3980ms, 4-mm thickness, field of view: 320x320mm, matrix 512x512)

8 MRI assessment MRI parameters Dural sac cross sectional area (DSCA) on axial images parallel to the intervertebral discs at L3/4, L4/5 and L5/S1 In both supine and standing positions 1.DSCA at individual levels L3/4, L4/5 and L5/S1 2.Total DSCA : summing individual DSCAs at L3/4, L4/5 and L5/S1 3.Narrowest DSCA : choosing smallest DSCA from these three levels 4.Absolute and percentage changes of DSCA, total DSCA and narrowest DSCA from supine and standing positions

9 MRI assessment Other MRI parameters: Exit foraminal stenosis using 4-point grading scales (Wildermuth) Lateral recess stenosis using 4-point grading scales (Weishaupt) In both supine and standing MRIs 1.Grading at individual level at L3/4, L4/5 and L5/S1 2.Total grading by summating grading of stenosis of corresponding sides at L3/4, L4/5 and L5/S1 3.Narrowest level by choosing highest grading of stenosis of corresponding sides from these three levels 4.Absolute changes of grading at individual level and total grading from supine and standing positions

10 Inter and intra- observer reliability Measurements performed independently by 2 independent authors (Radiologists: R.K.L.L, Spine surgeon: Y.L.) blinded to clinical data Data measured twice at an interval of 2 weeks by same observers

11 Statistics SPSS software (version 14.0, SPSS) for Windows Presented as mean ± standard deviation (sd) Intra-observer and inter-observer agreement (r) : - Kappa scores for non-parametric data - Interclass correlation for parametric data Correlation between MRI measurements and clinical data - Pearson (rp) : parametric data - Spearman correlation (rs) : non-parametric data Criteria of agreement (r) and correlation (rs and rp) : >0.8 excellent, good, moderate, fair, <0.2 poor Paired t-test : compare mean DSCA in supine and standing positions Wilcoxon Signed-Rank Test : compare lateral recess and exit foraminal stenosis grading in supine and standing MRIs Department of p Diagnostic Radiology Organ Imaging, Chinese University of Hong Kong Probability level of <0.05andregarded as The statistically significant.

12 Results Total 68 patients recruited Men : women = 28:40 Mean age : 58.2 ± 11.0 years (range years) Exclusion : 12 patients - intolerable back or leg pain during standing MRI (n=6) - severe motion artifact (n=6)

13 Results : DSCA Mean DSCA in standing and supine MRIs : L3/4: ± 33.1 mm2 and ± 50.0 mm2 L4/5: 61.9 ± 41.5 mm2 and 80.5 ± 41.5 mm2 L5/S1: 103.9± 48.5 mm2 and 115.7±45.36 mm2 Mean percentage change of DSCA from supine to standing : L3/4: -4.4% L4/5: -23.1%

14 DSCA Supine MRI

15 DSCA Standing MRI

16 DSCA : Standing vs supine MRI

17 Results DSCA summary DSCA at L4/5 significantly lower than at L3/4 or L5/S1 in both standing and supine positions (p : 0.01 to < ) Significant decrease in DSCA at L4/5 (p< ), at L5/S1 (p = ) and at narrowest level between supine and standing positions (p < )

18 Exit foramina and lateral recess : Supine

19 Exit foramina and lateral recess : Standing

20 Exit foramina and lateral recess : Standing Vs supine

21 Results : exit foraminal and lateral recess stenosis Grading of exit foraminal and lateral recess stenosis significantly higher at L4/5 than L3/4 and L5/S1 in both standing and supine positions (all p < 0.002) Significant increase in grading of exit foraminal and lateral recess stenosis from supine to standing position at all three levels (all p < 0.002) Similarly significant increase in total grading and highest grading of lateral recess stenosis and exit foraminal from supine to standing positions

22 Correlation of DSCA with clinical parameters

23 Correlation of DSCA with clinical parameters Fair correlation between DSCA at L4/5 in standing position to walking distance only (rp = 0.4, p = 0.002) Fair to moderate correlation between narrowest DSCA in both standing and supine positions to walking time and distance (rp = 0.3 to 0.5, all p<0.002) With slightly better correlation in the standing (rp = 0.4 to 0.5) than the supine position (rp = 0.3 to 0.4)

24 Correlation of exit foraminal stenosis and clinical parameters

25 Correlation of lateral recess stenosis and clinical parameters

26 Correlation of exit foraminal/lateral recess stenosis and clinical parameters Fair to moderate negative correlation between grading of lateral recess and exit foraminal stenosis in both standing and supine positions at L4/5 to walking time and distance (rs= to - 0.6, all p <0.01) With a slightly better correlation in the standing (rs= to - 0.6) than the supine (rs= to - 0.5) position Total grading and highest of lateral recess stenosis also showed fair to moderate negative correlation (rs= to 0.6, all p<0.05) to walking time and distance with slightly better correlation in the standing (rs= to - 0.6) than the supine (rs= to - 0.5) position

27 Inter- and Intra-observer reliabilities Inter- and Intra-observer reliabilities of DSCA : good [inter-observer: r = 0.61 p<0.05; intra-observer: r= 0.71, p<0.05 (observer 1) and r=0.70, p<0.05 (observer 2)] Inter- and intra-observer reliabilities of lateral recess and exit foraminal stenosis : good to excellent [inter-observer: r = , p<0.05; intra-observer: r = , p<0.05 (observer 1)/ r = , p<0.05 (observer 2)]

28 DSCA Supine MRI DSCA : 100mm2 Standing MRI DSCA: 85mm2

29 Exit foraminal stenosis Supine MRI L4/5: Grade 1 L5/S1: Grade 1 Standing MRI L4/5: Grade 2 L5/S1: Grade 2

30 Lateral recess stenosis Supine MRI Bilateral lateral recess stenosis : grade 1 Standing MRI Bilateral lateral recess stenosis : grade 2

31 Conclusion First standing MRI study analyzing clinical significance of dynamic changes in dural sac size, exit foraminal and lateral recess stenosis Standing MRI significantly increases central canal, lateral recess and foraminal stenosis but does not improve correlation with clinical symptoms which remains fair to modest

32 Thank You END