Table 2.
Comparison of clinical characteristics and CT findings between the groups with different absolute difference between the mean contrast-enhanced and nonenhanced attenuation values of thymic cysts.
| Parameter | Group of Artifactual Hyper-density | Group of Unchanged density | Group of Artifactual Hypo-density | P Value |
|---|---|---|---|---|
| Total No. of patients (n) | 27 | 38 | 19 | |
| Age (years) | 55.9 ± 9.1 | 51.0 ± 10.6 | 59.0 ± 12.5 | 0.023 |
| Sex | 0.025 | |||
| Men | 5 | 18 | 10 | |
| Women | 22 | 20 | 9 | |
| Diagnosis-treatment interval time | 5.2 ± 2.5 | 5.3 ± 3.7 | 4.9 ± 3.0 | 0.833 |
| Cyst Size | ||||
| Total No. of cysts (n) | 27 | 38 | 19 | |
| Long diameter (mm) | 23.7 ± 12.6 | 36.4 ± 24.7 | 34.3 ± 29.7 | 0.086 |
| Short diameter (mm) | 15.5 ± 8.2 | 24.3 ± 15.4 | 19.2 ± 11.9 | 0.025 |
| Nonenhanced CT attenuation | ||||
| Total No. of plain scans (n) | 27 | 38 | 19 | |
| CT attenuation of cysts (HU) | 30.7 ± 16.9 | 32.1 ± 17.6 | 38.2 ± 17.9 | 0.322 |
| CT attenuation of adjacent large vessel (HU) | 42.8 ± 7.0 | 48.7 ± 5.1 | 48.5 ± 3.9 | <0.001 |
| Contrast-enhanced CT attenuation of both arterial and venous phase | ||||
| Total No. of arterial and venous phase scans (n) | 47 | 68 | 25 | |
| CT attenuation of cysts (HU) | 46.2 ± 21.7 | 30.9 ± 18.0 | 26.6 ± 20.4 | <0.001 |
| CT attenuation of adjacent large vessel (HU) | 280.3 ± 68.8 | 222.5 ± 78.88 | 249.6 ± 74.2 | <0.001 |
According to the absolute difference in attenuation of the cysts between contrast-enhanced and nonenhanced CT, the patients were classified into the three groups of artifactual hyper-density (> 5 HU), unchanged density (-5~5 HU), and artifactual hypo-density (<-5 HU).