evidence-based medicine fellow 趙顗絢
TRANSCRIPT
Evidence-Based Medicine
Fellow 趙顗絢
Introduction
• OKU
– Ch8 musculoskeletal imaging
T1-weighted
T2-weighted
proton density-weighted (intermediate)
short-tau inversion recovery (STIR)
gradient-echo
– Ch42 spinal tumors
– Ch49 thoracolumbar trauma
Benign or Malignant
• Rothman
– Malignant: ill-defined, marked heterogenous
enhancement, pedicle, paravertebral mass
– Benign: fat present , focal edema, not pedicle,
not mass
Benign or Malignant
• MRI— the modality of choice
– Bone marrow edema (BME)
– Diffusion-weighted imaging (DWI)
– Opposed-phase (chemical shift) imaging
– A single or subset of potential discrimination
Materials & Methods
• Guidelines for conducting diagnostic
research synthesis, systematic reviews,
and meta-analyses
• MOOSE
– Meta-analyses of observational studies
• QUOROM
– Quality of reporting of meta-analyses
Search Strategy
– Through February 2011
– No limits or language restrictions
• MEDLINE
• EMBASE
• SCOPUS
• Cochrane
– Primary and review articles
Study Selection
• Two independent reviewers
• Title and abstracts
• Could not be excluded full text
• No disagreement between the reviewers
Study Inclusion & Exclusion Criteria
• Inclusion criteria
– Original reports: diagnostic performance
– A reference standard for etiology
– Raw data
• Exclusion criteria
– Duplicate articles
– Heterogeneous study population
– Multiple diagnostic modalities
– Technical notes, cases reports
Data Extraction
• Which features were reported
• The frequency
• To group similar features together
• Exclusion: not find enough information
• Exclusion: not emphasize the DDx
MRI features
Quality Assessment
• QUADAS tool
– Quality assessment of diagnostic accuracy
studies
Data Synthesis & Statistical Analyses
• Sensitivity and specificity
• Diagnostic odds ratio
– Pooled with a random-effects model
• if 95% confidence interval did not cross 1
• If the P value was less than 0.05
– Significantly different
Results
Results
• Malignant VCF
– primarily represent: Mets
– <4%: Myeloma
• 9 studies: vertebral level of involvement
• 4 studies: benign & malignant
– 95% thoracolumbar; 5% cervical (malignant)
Quality assessment
• QUADUS
MRI features
• Signal Intensity Characteristics
– Bone Marrow edema
– Complete replacement
– Band-like pattern
– Fluid sign
– DWI
– Contrast
MRI features
• Signal Intensity Characteristics
MRI features
• Morphological Characteristics
– A paraspinal mass
– Epidural mass
– Pedicle vs. Posterior
– Convexity (anterior)
– Convexity (posterior): diffuse vs. focal
– Disc
– Endplate
– All columns
MRI features
• Morphological Characteristics
MRI features
• Quantitative Characteristics
– Conventional pulse sequences (T1, T2, STIR)
contrast-to-noise ratio
signal intensity ratio (SIR)
– Opposed-phase (chemical shift) imaging
– Diffusion-weighted imaging (DWI)
MRI features
• Quantitative Characteristics
– Opposed-phase (chemical shift) imaging: SIR
<0.8: sensitivity 95% specificity 89%<0.65: sensitivity 95% specificity 100%
positive predictive value 100%negative predictive value 95.2%
1.0- and 1.5-T magnets
MRI features
• Quantitative Characteristics
– DWI: apparent diffusion coefficient (ADC)
Fat-suppressed echo planar imaging (EPI)
& higher b values (≧500): ADC<1.5×10-3
MRI features
• Quantitative Characteristics
MRI features
• Other Lesions (Outside of Index VCF)
– Multiple levels of VCF with BME: benign
– A coexisting healed benign VCF: benign
– Other non-characteristic lesions: malignant
MRI features
• Other Lesions (Outside of Index VCF)
Discussion
• Qualitative MRI vs. Quantitative MRI
• Opposed-phase (chemical shift)
– High discrimination capability
• Diffusion: ACS
– Biophysical & technical factors
– Water-specific models
– Absolute diffusion imaging, with EPI
– ADC: 1~1.5mm2/S
• Magnetic resonance spectroscopy
Research synthesis
• Individual studies
• Observer performance assessment
• A combination of various features
• Applying a constellation of criteria
the nature of a compression fracture
– a higher degree of certainty
– reduce interobserver variability
Limitations
• Convenience samples
– Spectrum bias (selection bias)
– Equivocal cases
– More common
• The unit of analysis was per VCF
• Features
• Myeloma and compression fracture
Future studies
• A robust VCF cohort
• Feature refinement
• Standardized MRI techniques
• Multiple readers
• Prediction model development
Thank You