title: Diffusion Tensor Imaging of Lumbar Nerve Roots: Comparison Between Fast Readout-Segmented and Selective-Excitation Acquisitions.
abstract: The aim of this study was to compare the quality of recently emerged advanced diffusion tensor imaging (DTI) techniques with conventional single-shot echo-planar imaging (EPI) in a functional assessment of lumbar nerve roots.
  
  
  
  The institutional review board approved the study including 12 healthy volunteers. Diffusion tensor imaging was performed at 3 T (MAGNETOM Skyra; Siemens Healthcare) with b-values of 0 and 700 s/mm and an isotropic spatial resolution for subsequent multiplanar reformatting. The nerve roots L2 to S1 were imaged in coronal orientation with readout-segmented EPI (rs-DTI) and selective-excitation EPI (sTX-DTI) with an acquisition time of 5 minutes each, and in axial orientation with single-shot EPI (ss-DTI) with an acquisition time of 12 minutes (scan parameters as in recent literature). Two independent readers qualitatively and quantitatively assessed image quality.
  
  
  
  The interobserver reliability ranged from "substantial" to "almost perfect" for all examined parameter and all 3 sequences (κ = 0.70-0.94). Overall image quality was rated higher, and artifact levels were scored lower for rs-DTI and sTX-DTI than for ss-DTI (P = 0.007-0.027), while fractional anisotropy and signal-to-noise ratio values were similar for all sequences (P ≥ 0.306 and P ≥ 0.100, respectively). Contrast-to-noise ratios were significantly higher for rs-DTI and ss-DTI than for sTX-DTI (P = 0.004-0.013).
  
  
  
  Despite shorter acquisition times, rs-DTI and sTX-DTI produced images of higher quality with smaller geometrical distortions than the current standard of reference, ss-DTI. Thus, DTI acquisitions in the coronal plane, requiring fewer slices for full coverage of exiting nerve roots, may allow for functional neurography in scan times suitable for routine clinical practice.
authors.affiliation: From the *Institute of Diagnostic and Interventional Radiology, and †Department of Neuroradiology, University Hospital Zurich, University of Zurich; ‡Siemens Healthcare AG, Zurich; and §Institute of Diagnostic Radiology, Regional Hospital Lugano, Lugano, Switzerland.
authors.forename: Andrei
authors.initials: A
authors.lastname: Manoliu
authors.forename: Michael
authors.initials: M
authors.lastname: Ho
authors.forename: Daniel
authors.initials: D
authors.lastname: Nanz
authors.forename: Marco
authors.initials: M
authors.lastname: Piccirelli
authors.forename: Evelyn
authors.initials: E
authors.lastname: Dappa
authors.forename: Markus
authors.initials: M
authors.lastname: Klarhöfer
authors.forename: Filippo
authors.initials: F
authors.lastname: Del Grande
authors.forename: Felix Pierre
authors.initials: FP
authors.lastname: Kuhn
mesh_terms: D000328:Adult; D016477:Artifacts; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000294:innervation*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D055815:Young Adult