TABLE 3.
Study Population Characteristics Stratified by Presence of Measured Pseudoenhancement
| Characteristic | Patients | Cysts Without Pseudoenhancement |
Cysts With Pseudoenhancement |
pa |
|---|---|---|---|---|
| Patient sex | 0.2 | |||
| Male | 42 (14/33) | 51 (35/68) | 36 (15/42) | |
| Female | 58 (19/33) | 49 (33/68) | 64 (27/42) | |
| Cyst location | 0.2 | |||
| Right kidney | NA | 47 (32/68) | 33 (14/42) | |
| Left kidney | NA | 53 (36/68) | 67 (28/42) | |
| Growth patternb | 0.02c | |||
| Exophytic | NA | 32 (22/68) | 7 (3/42) | |
| Mesophytic | NA | 31 (21/68) | 29 (12/42) | |
| Endophytic | NA | 37 (25/68) | 64 (27/42) | |
| Position | 0.2 | |||
| Upper pole | NA | 28 (19/68) | 45 (19/42) | |
| Interpolar | NA | 41 (28/68) | 36 (15/42) | |
| Lower pole | NA | 31 (21/68) | 19 (8/42) | |
| Tube current (mA), mean (SD)d | NA | 345 (88) | 320 (121) | 0.5 |
| CT detectors | 0.3 | |||
| 16-MDCT scannerd | 15 (5/33) | 15 (10/68) | 7 (3/42) | |
| 64-MDCT scannerd | 85 (28/33) | 85 (58/68) | 93 (39/42) | |
| Abdominal cross-sectional area (cm2), mean (SD) | NA | 734 (165) | 711 (175) | 0.5 |
| Cyst diameter (mm), mean (SD) | NA | 25 (16) | 14 (6) | 0.0004c |
| Parenchymal attenuation (HU), mean (SD)e | NA | 140 (20) | 152 (28) | 0.02c |
| Measured enhancement (HU) | —f | |||
| Mean (SD) | NA | 4 (4) | 15 (4) | |
| ≤ 10 | NA | 100 (68/68) | 0 (0/42) | |
| 11–19 | NA | 0 (0/68) | 93 (39/42) | |
| ≥ 20 | NA | 0 (0/68) | 7 (3/42) | |
Note—Except where noted otherwise, data are percentage of patients or cysts (no./total). Pseudoenhancement is defined as nephrographic phase CT attenuation minus unenhanced CT attenuation >10 HU.
NA = not applicable (i.e., the characteristic is a cyst-level characteristic and varied within patients).
p values refer to univariate comparisons between characteristics of cysts with vs without pseudoenhancement while controlling for repeated measures within patients.
Endophytic cysts had a significantly higher pseudoenhancement rate than did exophytic cysts in univariate analysis (p = 0.02; odds ratio, 7.90; 95% CI, 1.35–46.32). This finding lost significance in the multivariate model.
Statistically significant (p < 0.05).
All CT studies used 120 kVp, variable tube current, 2.5 mm collimation, and standard kernel.
Parenchymal attenuation in the nephrographic phase.
Not assessed, definitional.