Findings on intraprocedural non-contrast computed tomographic imaging following hepatic artery embolization are associated with development of contrast-induced nephropathy

Abstract

Background: Contrast-induced nephropathy (CIN) is a reversible form of acute kidney injury that occurs within 48-72 h of exposure to intravascular contrast material. CIN is the third leading cause of hospital-acquired acute kidney injury and accounts for 12% of such cases. Risk factors for CIN development can be divided into patient- and procedure-related. The former includes pre-existing chronic renal insufficiency and diabetes mellitus. The latter includes high contrast volume and repeated exposure over 72 h. The incidence of CIN is relatively low (up to 5%) in patients with intact renal function. However, in patients with known chronic renal insufficiency, the incidence can reach up to 27%.

Aim: To examine the association between renal enhancement pattern on non-contrast enhanced computed tomographic (CT) images obtained immediately following hepatic artery embolization with development of CIN.

Methods: Retrospective review of all patients who underwent hepatic artery embolization between 01/2010 and 01/2011 (n = 162) was performed. Patients without intraprocedural CT imaging (n = 51), combined embolization/ablation (n = 6) and those with chronic kidney disease (n = 21) were excluded. The study group comprised of 84 patients with 106 procedures. CIN was defined as 25% increase above baseline serum creatinine or absolute increase ≥ 0.5 mg/dL within 72 h post-embolization. Post-embolization CT was reviewed for renal enhancement patterns and presence of renal artery calcifications. The association between non-contrast CT findings and CIN development was examined by Fisher's Exact Test.

Results: CIN occurred in 11/106 (10.3%) procedures (Group A, n = 10). The renal enhancement pattern in patients who did not experience CIN (Group B, n = 74 with 95/106 procedures) was late excretory in 93/95 (98%) and early excretory (EE) in 2/95 (2%). However, in Group A, there was a significantly higher rate of EE pattern (6/11, 55%) compared to late excretory pattern (5/11) (P < 0.001). A significantly higher percentage of patients that developed CIN had renal artery calcifications (6/11 vs 20/95, 55% vs 21%, P = 0.02).

Conclusion: A hyperdense renal parenchyma relative to surrounding skeletal muscle (EE pattern) and presence of renal artery calcifications on immediate post-HAE non-contrast CT images in patients with low risk for CIN are independently associated with CIN development.

Keywords: Contrast-induced nephropathy; Hepatic artery embolization; Intra-arterial; Non-contrast computed tomographic; Renal artery calcification; Renal enhancement pattern.

Figure 1

Flow chart of study. CT: Computed tomography.

Figure 2

Example of Regions-of-interest drawn on the post-embolization non-contrast enhanced computed tomographic to determine the phase of renal enhancement. ROI 1 measures the Hounsfield units (HU) of the renal cortex. ROI 2 measures the HU of the renal medulla. ROI 3 measures the HU of the renal pelvis. ROI 4 measures the HU of surrounding skeletal muscle. In this example, the renal enhancement phase is late excretory.

Figure 3

Computed tomographic. A: Immediate post-embolization non-contrast computed tomographic demonstrating homogenous renal parenchymal enhancement (renal cortex and medulla) with Hounsfield units of 172 and incomplete opacification of renal collecting system, consistent with Early Excretory renal enhancement phase. Hyper enhancement of renal parenchyma compared to adjacent paraspinal skeletal muscle is evident; B: Immediate post-embolization non-contrast computed tomographic demonstrating complete opacification of the renal collecting system with renal parenchyma iso-dense to surrounding skeletal muscle, consistent with late excretory renal enhancement phase.

Figure 4

Any discernible plaque along the renal arteries with more than 130 Hounsfield units were considered calcifications. Immediate post-embolization non-contrast computed tomographic demonstrating renal artery calcifications in the right (arrow) (A) and left (arrow) (B) renal arteries.