TABLE 4.
Analysis of Effects on Measured Enhancement Detected by Contrast-Enhanced CT Within Nonenhancing Renal Cysts, Controlling for Repeated Measures Within Patients
| Covariate | Measured Enhancement (Continuous) | Measured Enhancement (Categoric, > or ≤ 10 HU) | ||||
|---|---|---|---|---|---|---|
| Univariate p | Multivariate p | OR (95% CI) | Univariate p | Multivariate p | OR (95% CI) | |
| Patient sex | 0.5 | — | — | 0.2 | — | — |
| Abdomen cross-sectional area (cm2) | 0.9 | — | — | 0.5 | — | — |
| Kidney (left or right) | 0.3 | — | — | 0.2 | — | — |
| Growth (exophytic, endophytic, or mesophytic)a | 0.03b | NS | — | 0.02b | NS | — |
| Position (upper, mid, or lower pole)c | 0.2 | — | — | 0.2 | — | — |
| CT detectors (16 or 64) | 0.4 | — | — | 0.3 | — | — |
| Tube current (mA) | 0.5 | — | — | 0.2 | — | — |
| Cyst diameter (mm) | < 0.0001b | < 0.0001d | −0.20 (−0.30 to −0.12) | 0.0004b | < 0.0004d | 0.86 (0.79–0.93) |
| Cyst area (mm2) | 0.0004b | NS | — | 0.009b | NS | — |
| Cyst attenuation unenhanced (HU) | 0.2 | — | — | 0.9 | — | — |
| Parenchymal attenuation (HU)e | 0.03b | 0.003d | 0.07 (0.03–0.12) | 0.02b | 0.002d | 1.04 (1.01–1.06) |
Note—Measured enhancement equals cyst nephrographic phase attenuation minus cyst unenhanced attenuation. Measured enhancement was treated as either a continuous or a categoric dichotomous variable. Dashes indicate that the covariate was not assessed.
OR = odds ratio, NS = not significant in the multivariate model.
Cyst growth pattern is a three-level categoric variable.
Included in multivariate analysis (p < 0.15).
Cyst position in the kidney is a three-level categoric variable.
Significant (p < 0.05) in multivariate analysis.
Parenchymal attenuation refers to nephrographic phase CT number of the closest normal renal parenchyma adjacent to the reference cyst.