Introduction
Basic issues of MR bone imaging
Current imaging techniques in MR bone imaging (Table 1)
Black bone imaging | Ultrashort/zero echo time sequences | 3D gradient-echo sequences |
---|---|---|
Product names (if any) | UTE, ZTE, PETRA, FFE3D with UTE Single-Echo and Multi-Echo | FRACTURE, 3D FLASH, VIBE, 3D SPGR, LAVA, 3D T1-FFE, THRIVE, FFE 3D Single-Echo and Multi-Echo, FE 3D Single-Echo and Multi-Echo |
Technique | ||
Indirect imaging of cortical bone Short TR/TE makes bone cortex hypointensity | Direct imaging of cortical bone High-speed switching between RF transmission and signal reception | Indirect imaging of cortical bone Short TR/TE with optimized flip angle |
Pros | ||
More CT-like images compared with 3D gradient-echo sequences Commonly available Low hardware/software requirements | Most CT-like images compared with other techniques | Commonly available Low hardware/software requirements Good depiction of soft tissues (ligaments, muscles, tendons, etc.) |
Cons | ||
Severe susceptibility artifacts | Not generally available High hardware/software requirements Moderate susceptibility artifacts Prone to motion artifacts | Severe susceptibility artifacts Prone to motion artifacts |
Available manufacture | ||
Any vendor | GE Siemens Canon | Philips Siemens GE Canon |
Black bone imaging
Ultrashort/zero echo time sequences
3D gradient-echo sequences
Other techniques
Imaging method used in this presentation
Scanner | Field strength | Sequence | |
---|---|---|---|
Avanto Fit (Siemens Healthineers) | 1.5 T | 3D-GRE sequence (VIBE) | |
TR | TE | NEX | Flip angle |
22 ms | 4.76, 9.53, 14.29, 19. 06 ms | 1 | 15 |
Field of view | In-plane spatial resolution | Slice thickness | Slab |
300 mm | 0.78 × 0.78 mm | 0.7 mm | 1 |
Imaging direction | PAT mode | Fat suppression | Scanning time |
sagittal | GRAPPA | none | 5 min 7 s |
Clinical applications
Modic type 2 change | Modic type 3 change | Disc herniation | Ossification of the posterior longitudinal ligament | Spondylolysis | Vertebral metastasis | Compression fracture | Spondylodiscitis | Hemangiomas | |
---|---|---|---|---|---|---|---|---|---|
Conventional MR findings | Hyperintensity on both T1/T2-weighted images | Hypointensity on both T1/T2-weighted images | Hypointensity on T2-weighted images Protusion/extrusion of the disc | Plate-like hypointensity on both T1/T2-weighted images | Often difficult to identify | Focal or diffuse signal changes May show pathological compression fracture | Changes in both signal and contour New lesions show cortical destruction and hyperintensity on fat-suppressed T2-weighted images | Disc space narrowing and endplate obscuration Bone marrow: hypointensity on T1-weighted images and hyperintensity on T2-weighted images Abnormal contrast enhancement | Hyperintensity on T2-weighted images Lipid-like hyperintensity on on T1-weighted images |
MR bone imaging findings | Decrease in trabeculae | Sclerotic change | Visualization of the OPLL (disrupted or spared) | Plate-like bony structure | Defect in the pars interarticularis like CT | Even small destructive or sclerotic lesion visualized | Impaction of trabeculae in new lesions Osteosclerotic changes in old lesions | Early depiction of endplate changes Demonstration of abnormalities of all compartments on a single image | Thickened trabeculae (like “polka-dot” sign on CT) with a clear margin |