In Vivo Predictors of Renal Cyst Pseudoenhancement at 120 kVp

Abstract

OBJECTIVE The purpose of this article is to assess the effects of various CT, patient, and renal cyst characteristics on the occurrence of pseudoenhancement in in vivo renal mass CT examinations using subtraction MRI as the reference standard. MATERIALS AND METHODS Adult patients imaged with 120-kVp standard kernel biphasic renal mass protocol CT and dynamic contrast-enhanced MRI of the abdomen from January 1, 2005, through May 4, 2012, were identified. Those with nonenhancing Bosniak categories I and II cysts on MRI were selected (n = 33 patients; 110 cysts). By treating measured cyst enhancement (nephrographic CT attenuation minus unenhanced CT attenuation) as either a continuous or categoric outcome variable, a variety of CT, patient-level, and renal cyst characteristics were assessed using mixed effect multivariate models. RESULTS On univariate assessment, cysts that exhibited pseudoenhancement (> 10 HU) were significantly more endophytic (p = 0.02), significantly smaller (p = 0.0004), and adjacent to significantly higher attenuation renal parenchyma in the nephrographic phase (p = 0.02). On multivariate assessment, cyst diameter (p < 0.0001) and background nephrographic phase parenchymal attenuation (p = 0.003) were the strongest in vivo predictors of pseudoenhancement. The odds of pseudoenhancement occurring increased by 2.14 (95% CI, 1.41–3.23) for every 5-mm decrease in renal cyst diameter and increased by 2.45 (95% CI, 1.41–4.26) for every 25-HU increase in enhanced renal parenchymal attenuation. Endophytic growth was not significant in the multivariate analyses (p = 0.07). CONCLUSION Renal cyst size and enhanced renal parenchymal attenuation are better in vivo predictors of pseudoenhancement than is endophytic growth pattern.

Effect of Model-Based Iterative Reconstruction on CT Number Measurements Within Small (10–29 mm) Low-Attenuation Renal Masses

“…Veo MBIR has no significant or consistent effect on attenuation measurements within small (10-29 mm) low-attenuation renal masses and is therefore unlikely to change clinically accepted attenuation thresholds for renal mass characterization. [11][12][13][14][15][16][17]. Pseudoenhancement is most common within small (< 20 mm) endophytic lesions surrounded by avidly enhancing renal parenchyma [12,[15][16][17].…”

The role of imaging in the management of renal masses

“…In a retrospective study of small (≤ 4 cm) indeterminate renal masses, CECT accuracy in predicting RCC diagnosis was 79.4 % [74]. Moreover, CT evaluation of small (≤ 1.5 cm) renal masses may be problematic, due to lesion pseudoenhancement and partial volume-averaging artifacts, which limit the assessment of contrast enhancement [76][77][78].…”

ACR Appropriateness Criteria® Indeterminate Renal Mass

“…In another retrospective study of 120 patients, the sensitivity and specificity of diagnosing RCC using CT was 94.5% and 27.7%, respectively [25]. Small ( 1.5 cm) renal masses are challenging to evaluate using CT because of the phenomenon of pseudoenhancement [26] and because the partial volume-averaging limits the assessment of the presence of enhancement in a renal mass [27].…”