Courtesy Dr. Aditya Daftary, Dr Ashok Shyam, Ortho TV
Imaging Approach to Multidrug-Resistant Tuberculosis (MDR-TB)
Overview
- Multidrug-Resistant Tuberculosis (MDR-TB) is a major clinical challenge, especially in high TB-burden regions
- Imaging plays a key role in:
- Detection
- Extent assessment
- Follow-up
Key Limitation
- Imaging cannot differentiate:
- Drug-resistant TB vs drug-sensitive TB
Role of Imaging in Tuberculosis
Common Imaging Modalities
- X-ray
- Computed tomography (CT)
- Magnetic resonance imaging (MRI)
- Positron emission tomography–CT (PET-CT)
What Imaging Helps Assess
- Bone involvement
- Soft tissue extension
- Disease activity
Key Limitation of Imaging
- No imaging modality can confirm drug resistance:
- MRI signal patterns — not specific
- CT enhancement — not specific
- PET-CT findings — not specific
Conclusion
- Imaging is supportive, not definitive for MDR-TB diagnosis
Typical Imaging Features of Spinal Tuberculosis
X-ray / CT Findings
- Vertebral body destruction
- Endplate erosion
- Paraspinal soft tissue swelling
- Multilevel involvement
MRI Findings
- Vertebral collapse
- Bone marrow edema
- Epidural or paraspinal collections
- Soft tissue involvement
PET-CT Findings
- Increased metabolic activity
- Helps assess:
- Disease extent
- Activity
Importance of Biopsy
Definitive Diagnosis Requires
- Tissue sampling
- Microbiological testing
- Drug sensitivity testing
Key Principle
- Target metabolically active tissue
Avoid
- Necrotic or inactive areas — poor yield
Best Technique
- CT-guided biopsy — higher accuracy
Role of Imaging in Biopsy Planning
Imaging Helps
- Identify optimal biopsy site
- Avoid non-representative tissue
PET-CT Advantage
- Differentiates:
- Active vs inactive regions
- Improves diagnostic yield
Assessment During Follow-Up
Indicators of Improvement
X-ray / CT
- Increased bone sclerosis
- Reduced soft tissue swelling
MRI
- Reduced abscess size
- Decreased soft tissue involvement
- Development of sclerosis
PET-CT
- Reduced metabolic activity
- Decreased disease extent
Challenges in Interpretation
- Imaging findings may be misleading:
- Vertebral collapse may progress despite healing
- Bone marrow edema may persist
- Residual collections may remain
Indicators of Disease Progression
- Increased metabolic activity (PET-CT)
- Enlargement of soft tissue components
- Lack of expected healing
Clinical Considerations
- Imaging must always be correlated with:
- Clinical findings
- Laboratory results
Important Rule
- No single imaging feature confirms:
- Disease activity
- Drug resistance
Key Messages
- Imaging is essential for:
- Evaluation
- Monitoring
- Imaging cannot diagnose MDR-TB
- Early, targeted biopsy is critical
- Follow-up imaging requires careful interpretation
- PET-CT provides functional assessment in complex cases
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