Table 2.
New Technologies for Human Cancer Imaging
| Clinical Problem | Cancer/Discipline | New Technology | Advantage | Disadvantage | Reference |
|---|---|---|---|---|---|
| Screening | Breast | Dedicated CT | High resolution and sensitivity | Ionizing radiation (same as 2-view mammogram) | 15,16 |
| PEM | High sensitivity, moderate to high resolution | Requires IV injection of radiotracer | 17 | ||
| DCE-MRI | High resolution and specificity | Requires IV injection of lanthanide chelate | 19 | ||
| Diffuse optical tomography (spectroscopy) | Noncontrast study, safe, 3-D, quantitative, high specificity, can be combined with MRI | Low resolution, low to moderate sensitivity | 27-29 | ||
| Endoscopy/colonoscopy/colposcopy | Optical (diffuse reflectance) | Fast, inexpensive, safe | Surface imaging only, interference from blood | 31 | |
| Optical (photon scattering) | Fast, inexpensive, safe | Surface imaging only, interference from blood | 32-34 | ||
| Optical (multi-wavelength spectroscopy) | Fast, inexpensive, safe | Surface imaging only, interference from blood | 35 | ||
| Optical (autofluorescence spectroscopy) | Fast, inexpensive, safe | Surface imaging only, interference from blood | 36 | ||
| Optical (polarization spectroscopy) | Fast, inexpensive, safe | Surface imaging only, interference from blood | 37 | ||
| Optical coherence tomography | Fast, high resolution, safe | Limited depth to ≈ 2 mm, endogenous contrast only | 38,39 | ||
| Exogenous fluorescence | High sensitivity and specificity | Requires IV injection of contrast agent | 40-42 | ||
| Virtual colonoscopy | CT-based | Noninvasive, relatively fast | Uses ionizing radiation, difficulty with flat lesions and small polyps | 43 | |
| MRI-based | Noninvasive, relatively fast | Difficulty with flat lesions and small polyps | 44 | ||
| Staging | PET | Replacements for SPECT radiotracers | Higher sensitivity and resolution | Desired half-life not always available | 47 |
| Time-of-flight detection | 2-fold higher resolution or sensitivity | Limited availability | 48,49 | ||
| MRI | Hyperpolarization | High sensitivity possible, in vivo tracking of molecule metabolism | Relatively short relaxation times of agents tested to date | 50,51 | |
| PARACEST | Higher sensitivity than traditional lanthanide imaging | Sensitivity not yet adequate for receptor-based imaging | 53 | ||
| All | Low-molecular weight targeting ligands | Rapid biodistribution and clearance | Tumor contact time often inadequate | 54-59 | |
| Signal amplification/background reduction (optical) | Improved SBR | Requires endocytosis and pH-dependent activation | 60 | ||
| Treatment | Chemotherapy | Image-guided treatment (18FDG-PET) | Highly sensitive | Expensive, not all tumors FDG-avid, difficult to quantify log kill | 61-63 |
| Image-guided treatment (99mTc-Annexin V) | Moderately sensitive | Presently unavailable, difficult to quantify log kill | 64-66 | ||
| Image-guided treatment (DCE-MRI) | No ionizing radiation | Requires intravenous injection of lanthanide chelate, difficult to quantify log kill | 67 | ||
| Image-guided treatment (optical spectroscopy) | No ionizing radiation, fast, safe, quantitative, high sensitivity and specificity | Low resolution, moderate sensitivity, difficult to quantify log kill | 68 | ||
| Radiotherapy | Ion beam-induced PET and PET/CT | Near real-time feedback on dose delivery | Requires specialized and expensive infrastructure, difficult mathematical modeling | 69 | |
| Surgery | Optical (reflectance NIR fluorescence) | Fast, real-time, high sensitivity and specificity | Poor depth penetration (≈1-3 mm) | 70-72,79,81,82,84 | |
| Optical (tomographic NIR fluorescence) | Depth penetration up to several cm, quantitative, high specificity | Requires separate acquisition and reconstruction, low to moderate resolution, low to moderate sensitivity | 73 |
Abbreviations: CT, computed tomography; PEM, positron emission mammography; IV, intravenous; DCE, dynamic contrast-enhanced; MRI, magnetic resonance imaging; SPECT, single photon emission computed tomography; PARACEST, paramagnetic chemical exchange saturation transfer; SBR, signal-to-background ratio; 18FDG, 2-deoxy-2-[18F]fluoro-D-glucose; 99mTc, technetium 99m; NIR, near-infrared.