Visualization of nerve fibers and their relationship to peripheral nerve tumors by diffusion tensor imaging.
OBJECT The majority of growing and/or symptomatic peripheral nerve tumors are schwannomas and neurofibromas. They are almost always benign and can usually be resected while minimizing motor and sensory deficits if approached with the proper expertise and techniques. Intraoperative electrophysiological stimulation and recording techniques allow the surgeon to map the surface of the tumor in an effort to identify and thus avoid damaging functioning nerve fibers. Recently, MR diffusion tensor imaging (DTI) techniques have permitted the visualization of axons, because of their anisotropic properties, in peripheral nerves. The object of this study was to compare the distribution of nerve fibers as revealed by direct electrical stimulation with that seen on preoperative MR DTI. METHODS The authors conducted a retrospective chart review of patients with a peripheral nerve or nerve root tumor between March 2012 and January 2014. Diffusion tensor imaging and intraoperative data had been prospectively collected for patients with peripheral nerve tumors that were resected. Preoperative identification of the nerve fiber location in relation to the nerve tumor surface as seen on DTI studies was compared with the nerve fiber's intraoperative localization using electrophysiological stimulation and recordings. RESULTS In 23 patients eligible for study there was good correlation between nerve fiber location on DTI and its anatomical location seen intraoperatively. Diffusion tensor imaging demonstrated the relationship of nerve fibers relative to the tumor with 95.7% sensitivity, 66.7% specificity, 75% positive predictive value, and 93.8% negative predictive value. CONCLUSIONS Preoperative DTI techniques are useful in helping the peripheral nerve surgeon to both determine the risks involved in resecting a nerve tumor and plan the safest surgical approach.
Departments of 1 Neurological Surgery and.
Tene A
TA
Cage
Radiology.
Esther L
EL
Yuh
Radiology.
Stephanie W
SW
Hou
School of Medicine, University of California, San Francisco, California;
Harjus
H
Birk
Prince of Wales Clinical School, University of New South Wales Australia, Sydney, Australia; and.
Neil G
NG
Simon
Departments of 1 Neurological Surgery and.
Roger
R
Noss
Radiology.
Anuradha
A
Rao
Radiology.
Cynthia T
CT
Chin
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
Michel
M
Kliot
D000293:Adolescent; D000328:Adult; D000368:Aged; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D010524:Peripheral Nervous System Neoplasms / Q000175:diagnosis* / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
DTI = diffusion tensor imaging; FA = fractional anisotropy; GTR = gross-total resection; IDEAL = iterative decomposition of water and fat with echo asymmetry and least-squares estimation; MRI; MRN = MR neurography; NPV = negative predictive value; PPV = positive predictive value; diffusion tensor imaging; nerve tumor; tractography