Detection of lymph nodes in pelvic malignancies with computed tomography and magnetic resonance imaging

Thirty patients with prostate or bladder cancer underwent CT and MRI for nodal staging. CT detected 189 nodes, and MRI detected 271 nodes. This difference was statistically significant in the external iliac (CT/MRI=73/87 nodes), obturator (CT/MRI=48/75 nodes), and internal iliac (CT/MRI=24/46 nodes) nodal chains. Based on size, the number of nodes detected by CT and MRI were as follows: 1–5 mm, CT/MRI=91/166; 6–10 mm, CT/MRI=91/98; >10 mm, CT/MRI=7/7 nodes. MRI detected significantly more lymph nodes in the size range of 1–5 mm.