Imaging Can Distinguish Complex Renal Lesions From Simple Cysts

Leesburg, VA, January 10, 2019—Follow-up imaging may not be required in all cases of incidentally discovered renal lesions on lumbar spine MRI, according to an article in the January 2019 issue of the American Journal of Roentgenology (AJR).

Incidentally discovered renal lesions on lumbar spine MRI are a common occurrence. Many follow-up recommendations are generated by radiologists encountering renal lesions to help characterize the finding as a benign cyst or a more complex, potentially malignant lesion. The study examined whether analysis of T2-weighted imaging features of incidentally discovered renal lesions could reliably distinguish complex renal lesions from simple cysts.

Two independent readers retrospectively evaluated 149 renal lesions identified on lumbar spine MRI examinations. Presence or absence of a complex renal lesion was determined using T2-weighted imaging only. Using dedicated renal cross-sectional imaging examinations as the reference standard, statistical analysis was performed to determine the accuracy of lumbar spine MRI in predicting a complex and potentially neoplastic renal lesion.

Of 149 renal lesions, 115 were simple cysts, and 34 were complex renal lesions. Lumbar spine MRI readers identified 72 lesions as simple cysts and 77 lesions as complex renal lesions. Reader sensitivity for detection of a complex renal lesion on lumbar spine MRI was 94%, specificity was 63%, positive predictive value was 43%, and negative predictive value (NPV) was 97%. Readers correctly identified all neoplastic and potentially neoplastic lesions.

The results showed that axial T2-weighted imaging on lumbar spine MRI has high sensitivity and high NPV in the detection of a complex renal lesion and appears to reliably allow neoplastic and potentially neoplastic causes to be ruled out. If an incidental renal lesion has homogeneous internal T2 signal intensity similar to CSF without associated internal septations or nodularity, follow-up imaging may not be required. In addition, more judicious patient selection for follow-up renal imaging recommendations on lumbar spine MRI may decrease the number of low-diagnostic-yielding follow-up examinations and lower associated healthcare costs.

Founded in 1900, ARRS is the first and oldest radiology society in the United States, and is an international forum for progress in radiology. The Society's mission is to improve health through a community committed to advancing knowledge and skills in radiology. ARRS achieves its mission through an annual scientific and educational meeting, publication of the American Journal of Roentgenology (AJR) and InPractice magazine, topical symposia and webinars, and print and online educational materials. ARRS is located in Leesburg, VA.