Table 1. Summary of the Main Characteristics of Functional and Hybrid Imaging of Bone Metastases.
| Modality | Hybrid modality | Ionizing radiation | Subtype | Mechanism | Advantages | Disadvantages |
|---|---|---|---|---|---|---|
| Radiography | Yes | Calcium in mineralized bone causes contrast in image | Inexpensive, widely available, relatively low radiation dose, high spatial resolution | Insensitive for detection and response assessment, morphology only, low contrast resolution | ||
| CT | SPECT/CT, PET/CT | Yes | Calcium in mineralized bone causes contrast in image. | Widely available, high contrast resolution, tomographic images in any plane, also reports on soft tissue disease | Insensitive for detection and response assessment in bone; morphology only | |
| Bone scintigraphy | SPECT/CT | Yes | 99mTc-MDP | Uptake depends on blood flow and mineralization rate. | Widely available, inexpensive, sensitive for detection, high contrast resolution (augmented by SPECT) | Uptake not cancer-specific (improved with SPECT/CT), false-positive flare phenomenon, low spatial resolution |
| MRI | PET/MRI | No | Morphologic | Signal contrast depends on proton density (water content) | Sensitive for tumor within marrow, high spatial and contrast resolution, no radiation | Insensitive for mineralized bone, relatively expensive |
| No | DW-MRI | Signal contrast depends on restriction of water molecule motion. | High sensitivity for tumor, no contrast required, quantitative changes in signal with therapy | May be less sensitive for sclerotic lesions, longer scan acquisition time | ||
| No | DCE-MRI | Signal contrast depends on blood flow and perfusion. | Quantitative changes in signal with therapy | Requires IV contrast, requires modeling for parameter measurement | ||
| PET | PET/CT, PET/MRI | Yes | 18F-fluoride | Uptake depends on blood flow and mineralization rate | Sensitive for detection, high contrast resolution, tomographic images in any plane | Uptake not cancer-specific (improved with PET/CT), false-positive flare phenomenon, relatively expensive |
| Yes | 18F-FDG | Uptake depends on tumor glucose transporters and glycolytic metabolism. | Tomographic images in any plane, sensitive for detection and therapy response assessment | Less sensitive for osteoblastic metastases and prostate cancer, relatively expensive | ||
| Yes | 11C/18F-choline | Uptake depends on choline transporters and choline kinase activity (cell membrane turnover). | Tomographic images in any plane, good sensitivity in prostate cancer | Insensitive at low PSA levels (eg, <1 ng/mL), relatively expensive | ||
| Yes | 68Ga-PSMA | Uptake depends on the level of tumor PSMA expression | Tomographic images in any plane, high sensitivity and specificity for prostate cancer in bone and soft tissues | Not specific to prostate cancer, relatively expensive |
CT = computed tomography; SPECT = single photon emission computed tomography; MDP = methylene diphosphonate; PET = positron emission tomography; FDG = fluorodeoxyglucose; PSMA = prostate-specific membrane antigen; DW-MRI = diffusion-weighted magnetic resonance imaging; DCE-MRI = dynamic contrast-enhanced MRI; IV = intravenous; 11C = carbon-11; 18F = fluorine-18; 68Ga-gallium.