Value of diffusion-weighted imaging to detect small malignant pelvic lymph nodes at 3 T.
OBJECTIVE
To investigate the usefulness of diffusion-weighted imaging (DWI) to discriminate between metastatic and non-metastatic small lymph nodes in pelvic carcinoma.


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.


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) mm(3)/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.


CONCLUSIONS
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.
Roy
Catherine
C
Department of Radiology B, Universitary Hospital of Strasbourg, Strasbourg, France. catherine.roy@chru-strasbourg.fr
Bierry
Guillaume
G
Matau
Andrea
A
Bazille
Gauthier
G
Pasquali
Rémy
R
D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D010386:Pelvic Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity