Fig. 3 –

Initial computed tomography (CT) obtained 11 mo prior to SAbR, magnetic resonance imaging (MRI) obtained 3 wk prior to SAbR, and surveillance MRI at 6 mo and 5 yr after SAbR of a patient with a single functional kidney (ie, congenital atrophic right kidney; open arrow on baseline CT) and a left renal mass (solid arrow). Percutaneous biopsy confirmed grade 3 clear cell renal cell carcinoma. The renal mass exhibited growth from 2.5 cm (11 mo prior to SAbR) to 2.7 cm (baseline, 3 wk prior to SAbR). The patient was treated with 36 Gy in five fractions. Follow-up MRI showed a decrease in size on initial follow-up to 2.3 cm (6 mo after SAbR) and subsequently to 1.9 cm (5 yr after SAbR). T1-weighted fat-saturated gradient-echo contrast-enhanced images obtained during the delayed nephrographic phase (top row) show progressively increased enhancement after SAbR, while T2-weighted images (bottom row) show increased signal intensity after treatment suggestive of treatment-induced fibrosis in the renal mass. SAbR = stereotactic ablative radiotherapy.