MR imaging in the characterization of small renal masses

Jonathon M. Willatt*, Hero K. Hussain, Suzanne Chong, Mariam Kappil, Shadi F. Azar, Peter S. Liu, Julie A. Ruma, Khaled M. Elsayes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Objective: The aim of our study was to evaluate the effectiveness of MR imaging for the characterization of small (<2 cm) renal lesions described as indeterminate on prior US or CT Materials and methods: Sixty-three small renal masses in 51 patients considered indeterminate on prior ultrasound or CT scans were included in the study. A retrospective evaluation of the examinations was performed independently by two body magnetic resonance imaging (MRI) radiologists who were unaware of the final diagnosis. A 3-point confidence scale (1: benign, 2: indeterminate, and 3: malignant) was established to determine the level of suspicion for malignancy. Interobserver agreement was determined with a weighted kappa statistic. The diagnosis was verified by imaging follow-up of at least 24 months (mean 60 months) in 53 lesions and by pathology in 10 lesions. Results: MRI detected all eight malignancies in the series. There were eight malignant lesions and two benign lesions among those with pathologic follow-up. No interval growth or evidence of malignancy in the remaining 53 lesions was found for a minimum of 24 months by repeat imaging. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI for differentiating benign from malignant small renal lesions were 100% (62.9-100%, 95% CI), 94.5% (84.9-98.8%, 95% CI), 72.7% (39.1-93.6%, 95% CI), and 100% (93.1-100%, 95% CI), respectively. The kappa value for interobserver agreement was 0.77 (95% CI 0.59-0.96, p-value <0.001). Conclusion: MR imaging is an effective method for characterizing small (<2 cm) renal masses found to be indeterminate by US or CT.

Original languageEnglish (US)
Pages (from-to)761-769
Number of pages9
JournalAbdominal Imaging
Issue number4
StatePublished - Aug 2014


  • CT
  • MRI
  • Mass
  • Renal
  • Ultrasound

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Gastroenterology
  • Urology


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