Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms

Abdom Radiol (NY). 2017 Jun;42(6):1734-1743. doi: 10.1007/s00261-017-1061-3.

Abstract

Objective: To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms.

Materials and methods: Two independent cohorts-an initial (biopsy) dataset and a validation (surgical) dataset-with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion-Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated.

Results: Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephrographic phase (p < 0.001), early excretory phase (p < 0.001), and excretory phase (p = 0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00-1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%-100%) and specificity was 81.5 (61.9%-93.7%). When tested on the validation dataset on measurements made by an independent reader, the AUROC was 0.93 (95% CI: 0.84-1.00) with a sensitivity of 100 (80.0%-100%) and a specificity of 87.5 (60.4%-97.8%).

Conclusions: Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate.

Keywords: Biomarker; Chromophobe; Computed tomography (CT); Oncocytic neoplasm; Oncocytoma; Renal cell Caecinoma.

MeSH terms

  • Adenoma, Oxyphilic / diagnostic imaging*
  • Adenoma, Oxyphilic / pathology*
  • Adult
  • Aged
  • Aged, 80 and over
  • Aorta / diagnostic imaging
  • Biopsy
  • Carcinoma, Renal Cell / diagnostic imaging*
  • Carcinoma, Renal Cell / pathology*
  • Contrast Media
  • Diagnosis, Differential
  • Female
  • Humans
  • Kidney Neoplasms / diagnostic imaging*
  • Kidney Neoplasms / pathology*
  • Male
  • Middle Aged
  • Retrospective Studies
  • Sensitivity and Specificity
  • Tomography, X-Ray Computed / methods*

Substances

  • Contrast Media

Supplementary concepts

  • Oncocytoma, renal