Discrimination between Lumbar Intraspinal Stenosis and Foraminal Stenosis using Diffusion Tensor Imaging Parameters: Preliminary Results.
METHODS
Retrospective observational study.


OBJECTIVE
To examine fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values of damaged nerves to discriminate between lumbar intraspinal stenosis (IS) and foraminal stenosis (FS) using diffusion tensor imaging (DTI).


BACKGROUND
It is important in the selection of surgical procedure to discriminate between lumbar IS and FS, but such discrimination is difficult.


METHODS
There were 9 cases of IS, 7 cases of FS, and 5 healthy controls. The regions of interest were established in the lumbar intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez). The FA and ADC values were measured on the affected and unaffected sides of the nerves. The FA ratio and the ADC ratio were calculated as the affected side/unaffected side ×100 (%).


RESULTS
In the Ez, the FA value was significantly lower in FS than in IS (p<0.01). FA ratio was significantly lower in FS than in IS for the Ez (p<0.01). In the Iz, the ADC value was significantly higher in IS than FS (p<0.01). ADC ratio was significantly higher in FS than in IS for the N and Ez (p<0.05). For the Ez, receiver operating characteristic analysis of parameters revealed that the FA values showed a higher accuracy for the diagnosis of FS than the ADC values, and the FA value cut-off value was 0.42 (sensitivity: 85.7%, false positive: 11.1%) and the FA ratio cut-off value was 83.9% (sensitivity: 85.7%, false positive: 22.2%).


CONCLUSIONS
The low FA value in the extraforaminal zone suggests the presence of foraminal stenosis. When the FA value and FA ratio cut-off value were established as 0.42 and 83.9%, respectively, the accuracy was high for the diagnosis of foraminal stenosis. It may be possible to use DTI parameters to help in the discrimination between IS and FS.
Department of Orthopaedic Surgery, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Japan.
Yawara
Y
Eguchi
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Seiji
S
Ohtori
Department of Orthopaedic Surgery, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Japan.
Munetaka
M
Suzuki
Division of Orthopaedic Surgery, Chiba Children's Hospital, Chiba, Japan.
Yasuhiro
Y
Oikawa
Department of Orthopaedic Surgery, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Japan.
Hajime
H
Yamanaka
Department of Orthopaedic Surgery, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Japan.
Hiroshi
H
Tamai
Department of Orthopaedic Surgery, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Japan.
Tatsuya
T
Kobayashi
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Sumihisa
S
Orita
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Kazuyo
K
Yamauchi
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Miyako
M
Suzuki
Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Chiba, Japan.
Yasuchika
Y
Aoki
Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Chiba, Japan.
Atsuya
A
Watanabe
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Hirohito
H
Kanamoto
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Kazuhisa
K
Takahashi
Apparent diffusion coefficient; Diffusion tensor imaging; Fractional anisotropy; Lumbar foraminal stenosis