title: Fusion of high b-value diffusion-weighted and T2-weighted MR images improves identification of lymph nodes in the pelvis.
abstract: Accurate identification of lymph nodes facilitates nodal assessment by size, morphological or MR lymphographic criteria. We compared the MR detection of lymph nodes in patients with pelvic cancers using T2-weighted imaging, and fusion of diffusion-weighted imaging (DWI) and T2-weighted imaging. Twenty patients with pelvic tumours underwent 5-mm axial T2-weighted and DWI (b-values 0-750 s/mm(2)) on a 1.5T system. Fusion images of b = 750 s/mm(2) diffusion-weighted MR and T2-weighted images were created. Two radiologists evaluated in consensus the T2-weighted images and fusion images independently. For each image set, the location and diameter of pelvic nodes were recorded, and nodal visibility was scored using a 4-point scale (0-3). Nodal visualisation was compared using Relative to an Identified Distribution (RIDIT) analysis. The mean RIDIT score describes the probability that a randomly selected node will be better visualised relative to the other image set. One hundred fourteen pelvic nodes (mean 5.9 mm; 2-10 mm) were identified on T2-weighted images and 161 nodes (mean 4.3 mm; 2-10 mm) on fusion images. Using fusion images, 47 additional nodes were detected compared with T2-weighted images alone (eight external iliac, 24 inguinal, 12 obturator, two peri-rectal, one presacral). Nodes detected only on fusion images were 2-9 mm (mean 3.7 mm). Nodal visualisation was better using fusion images compared with T2-weighted images (mean RIDIT score 0.689 vs 0.302). Fusion of diffusion-weighted MR with T2-weighted images improves identification of pelvic lymph nodes compared with T2-weighted images alone. The improved nodal identification may aid treatment planning and further nodal characterisation.
authors: Department of Radiology, Royal Marsden NHS Foundation Trust, Surrey, UK.
authors: N
authors: N
authors: Mir
authors: S A
authors: SA
authors: Sohaib
authors: D
authors: D
authors: Collins
authors: D M
authors: DM
authors: Koh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008198:Lymph Nodes / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010386:Pelvic Neoplasms / Q000473:pathology*; D010388:Pelvis / Q000473:pathology; D012189:Retrospective Studies