Value of diffusion-weighted imaging to detect small malignant pelvic lymph nodes at 3 T
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To investigate the usefulness of diffusion-weighted imaging (DWI) to discriminate between metastatic and non-metastatic small lymph nodes in pelvic carcinoma.
Materials and Methods
A total of 259 patients (180 normal, 79 metastatic) prospectively underwent DWI at 3 T. We measured the short-axis diameter and the mean apparent diffusion coefficient (ADC) value. Lymph nodes with a short-axis diameter larger than 8 mm were recorded as being suspected metastatic lymph nodes. Imaging data were correlated station by station with histopathological results.
A total of 140 metastatic nodes were accurately matched with histology. On T2w, the short-axis diameter for non-metastatic and metastatic lymph nodes was 6.4 mm ± 2.5 mm and 8.3 mm ± 4.5 mm, respectively. Almost all metastatic or non-metastatic nodes had similar high signal intensity on DWI (except in 5 cases) with a homogeneous pattern. The mean ADC values (10−3 mm3/s ± standard deviation) of involved lymph nodes, control iliac nodes and control inguinal nodes were 924 ± 217, 968 ± 182 and 1,036 ± 181, respectively. There were no statistically significant differences in the ADC of metastatic and non-metastatic nodes.
Isolated measurement of mean ADC values in a suspected station does not contribute to the diagnosis of metastatic nodes, in patients with small ambiguous nodes.
KeywordsDiffusion-weighted magnetic resonance imaging Pelvic neoplasms Lymphatic metastasis Lymph nodes
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