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Inter- and intraexaminer reliability in identifying and classifying degenerative marrow (Modic) changes on lumbar
Cynthia K Peterson1, Brian Gatterman, J C Carter
1Department of Radiology, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. cpeterson@cmcc.ca
Objective:
Signal intensity changes noted on magnetic resonance imaging scans in degenerated disks and adjacent bone marrow have been described and labeled "Modic" changes. Three types are identified, with type 1 being linked to low back pain. This study reports on the reliability of identifying and categorizing Modic marrow changes as would be done in the normal course of clinical practice.
Methods:
Fifty-one lumbar spine sagittal magnetic resonance imaging scans of adult male patients older than 40 years were used. Two radiologists independently read each case at 2 different periods; scans were reordered for the second reading. The radiologists recorded the presence or absence of Modic changes anywhere in the lumbar spine for each case and classified each one as type 1, type 2, or type 3, and the level or levels where they were noted. The kappa statistic was used to evaluate inter- and intraexaminer agreement overall and by disk level. Percent agreement was also calculated.
Results:
The overall kappa value for the interexaminer agreement of diagnosing the presence/absence of Modic changes for the entire lumbar spine as well as classifying them when present was kappa = 0.52 (moderate) with 71% agreement. At the L4 through 5 level, the kappa value was 0.81 (substantial) with 92% agreement, and at the L5 through S1 level, the kappa value was 0.58 (upper moderate) with 76% agreement. The L3 through L4 level had a kappa value of 0.66 (strong) but was considered "unstable" because of the lack of variability within the cells of the contingency table. The intraexaminer reliability gave a kappa value of 0.71 (strong) (82% agreement) for examiner 1 and a kappa value of 0.87 (almost perfect) (92%) for examiner 2.
Conclusions:
The Modic classification system shows moderate to almost perfect inter- and intraexaminer reliability in this study, simulating the methods of diagnosis used in clinical/radiological practice. The results of studies using the Modic system before investigations of its reliability can be viewed with more confidence, and future studies can continue to evaluate the link with patient symptoms and treatment outcomes.
Insights
Modic changes on MRI scans show moderate to almost perfect reliability for identification and classification by radiologists. This supports confidence in previous research and future studies on low back pain.
Area of Science:
- Radiology
- Orthopedics
- Spine Imaging
Background:
- Modic changes are signal intensity variations in degenerated intervertebral discs and adjacent bone marrow on MRI.
- Three types of Modic changes exist, with Type 1 associated with low back pain.
Purpose of the Study:
- To assess the reliability of identifying and categorizing Modic marrow changes in clinical practice.
- To evaluate inter- and intra-examiner agreement for Modic change classification.
Main Methods:
- Analysis of 51 lumbar spine MRI scans from male patients over 40.
- Two radiologists independently assessed scans twice, recording presence, absence, type, and location of Modic changes.
- Kappa statistic and percent agreement were used to measure inter- and intra-examiner reliability.
Main Results:
- Overall inter-examiner agreement for Modic changes was moderate (kappa = 0.52, 71% agreement).
- Substantial agreement was found at L4-L5 (kappa = 0.81) and upper moderate at L5-S1 (kappa = 0.58).
- Intra-examiner reliability was strong (kappa = 0.71) to almost perfect (kappa = 0.87).
Conclusions:
- The Modic classification system demonstrates moderate to almost perfect inter- and intra-examiner reliability in a clinical setting.
- This reliability supports confidence in prior studies and future research on Modic changes and patient outcomes.
