Significance of Arterial Spin Labeling for Reducing Biopsies in Patients With Kidney Allograft Dysfunction.

Background: Although biopsy is often entailed for managing patients with kidney allograft dysfunction, it is associated with potential complications of severe hemorrhage. Arterial spin labeling (ASL) is a non-invasive technique that assesses tissue perfusion.

Purpose: To assess the utility of ASL for the discrimination of patients with post-transplant allograft dysfunction who do not need biopsy from those who need.

Study Type: Prospective.

Subjects: Forty-six patients (34 males/12 females, aged 38.8 ± 9.5 years) with kidney allograft dysfunction, including 31 in which biopsy directly lead to changes in management (NECESSARY group) and 15 in which clinical management did not alter after biopsy (UNNECESSARY group).

Field Strength/sequence: 3.0 T and 3D fast-spin echo sequence.

Assessment: All patients underwent both ASL scan and biopsies. The serum creatinine, proteinuria, pathologic results, and cortical ASL readings were obtained and compared between the two groups.

Statistical Analyses: Chi-square test, independent student t-test, Mann-Whitney U test, receiver-operating characteristic curve. A two-tailed P < 0.05 denoted statistical significance.

Results: The NECESSARY group presented with significantly elevated serum creatinine as compared with the UNNECESSARY group (1.87 ± 0.56 mg/dL vs. 1.31 ± 0.37 mg/dL). The acute composite score was significantly higher in the NECESSARY group than that in the UNNECESSARY group (7 [4-8] vs. 1 [0-2]). Cortical ASL in the NECESSARY group was significantly decreased as compared with the UNNECESSARY group (108.06 [69.96-134.92] mL/min/100 g vs. 153.48 [113.19-160.37] mL/min/100 g). Serum creatinine differentiated UNNCESSARY group from the NECESSARY group with an area under the curve (AUC) and specificity of 0.79 and 54.84%, respectively. By comparison, the cortical ASL yielded an AUC of 0.75 and a specificity of 70.97%. Notably, the specificity was increased to 90.30% by combined use of serum creatinine and cortical ASL.

Data Conclusion: The combined use of ASL and serum creatinine yielded a high specificity for selecting patients who may not need allograft biopsy.

Level Of Evidence: 2 TECHNICAL EFFICACY: Stage 3.