Table 1.
Radiographic Characteristics of Thymic Hyperplasia Versus Type B1 Thymoma
| Radiographic Features | Normal | Thymic Hyperplasia | Type B1 Thymoma | Case Patient |
|---|---|---|---|---|
| General findings | ||||
| Pattern of enlargement | N/A | Normal (45%) Symmetric/diffuse (35%) Asymmetric/focal mass (20%) |
Asymmetric/focal mass: Round/oval (48%) Lobulated (45%) Amorphous (2%) |
Diffuse |
| Location | N/A | Midline (if focal mass) | Eccentric | N/A |
| Calcification | − | − | ± | − |
| Lymphadenopathy | − | − | − | + |
| Changes in size over time | Decreases | Can increase or decrease | Increases | Decreases |
| CT | ||||
| Density | <20 y: soft tissue density 20–50 y: heterogeneous (from progressive fatty infiltration) >50 y: fat density |
Homogeneous vs. heterogeneous (if macroscopic fat is present) | Homogeneous vs. heterogeneous (if necrosis, hemorrhage, cystic change, calcification is present) | Homogeneous |
| Enhancement | Homogeneous | Homogeneous | Heterogeneous | Homogeneous |
| MRI | ||||
| CSR | 0.5–0.6 | 0.5–0.6 | 0.8–1.0 | 0.97 |
| SII, % | >8.92 | >8.92 | <8.92 | 10.8 |
| Diffusion-weighted imaging (ADC values) | >2.01 × 10-3 | >1.625 × 10-3 | <1.625 × 10-3 | 8.9 × 10-3 |
| Nuclear medicine | ||||
| FDG uptake (SUV) | 1.0–1.8 | 2.0–2.8 | >4.0 | 5.3 |
| Indium-111-DTPA-octreotide uptake | − | − | + | Not performed |
ADC, apparent diffusion coefficient; CSR, chemical shift ratio; CT, computed tomography; FDG, fluorodeoxyglucose; MRI, magnetic resonance imaging; N/A, not applicable; SII, signal intensity index; SUV, standardized uptake value.