title: Diffusion-weighted MR imaging (DWI) in the evaluation of epidural spinal lesions.
abstract: BACKGROUND
  Epidural spinal cord compression is one of the most critical emergency conditions requiring medical attention and requires prompt and adequate treatment. The aim of our study was to assess the role of diffusion-weighted magnetic resonance (MR) imaging (DWI) in the diagnosis and differentiation of epidural spinal lesions.
  
  
  METHODS
  Three patients with epidural lymphoma, two with sarcoma and three with epidural metastatic disease were imaged on a 1.5T MRI unit. DWI was performed using navigated, interleaved, multi-shot echo planar imaging (IEPI). Three region of interest (ROI)-measurements were obtained on corresponding apparent diffusion coefficient (ADC) maps, and the mean ADC value was used for further analysis. The cellularity of tumors was determined as the N/C ratio (nucleus/cytoplasma ratio) from histological samples. The ADC values and N/C ratios of lesions were compared using a Kruskal-Wallis test.
  
  
  RESULTS
  The mean ADC of the lymphomas was 0.66 x 10(-3) mm2/s, that of the sarcomas was 0.85 x 10(-3) mm2/s and the ADC of the metastatic lesions was 1.05 x 10(-3) mm2/s; however, the differences were not statistically significant. Mean N/C ratios in the lymphoma, sarcomas and metastases were 4:1, 2:1, and 2.6:1, respectively, with a statistically significant difference between the groups (p < 0.025).
  
  
  CONCLUSIONS
  Although not statistically significant due to the small patient sample, our results clearly show a tendency toward decreased diffusivity in neoplastic lesions with higher cellularity. The data from our study suggest that DWI is a feasible and potentially useful technique for the evaluation of epidural lesions that cause spinal cord compression on a per-patient basis.
authors.affiliation: Department of Radiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Christina
authors.initials: C
authors.lastname: Plank
authors.forename: Anke
authors.initials: A
authors.lastname: Koller
authors.forename: Christina
authors.initials: C
authors.lastname: Mueller-Mang
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Majda M
authors.initials: MM
authors.lastname: Thurnher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013117:Spinal Cord Compression / Q000175:diagnosis* / Q000209:etiology; D013125:Spinal Neoplasms / Q000150:complications / Q000175:diagnosis*; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media