Keywords:
Education and training, Equipment, Diagnostic procedure, MR, Neuroradiology spine
Authors:
H. Sasani1, M. Vural2, M. SASANI2; 1TEKİRDAG/TR, 2Istanbul/TR
DOI:
10.26044/ecr2019/C-0019
Methods and materials
This study was planned retrospectively between years 2008-2017.
The study included 103 consecutive patients,
presented with only neurogenic claudication and/or without low back pain.
Patients who presented with radiating leg pain and/or only low back pain without neurogenic claudication were excluded from the study groups.
There were 43 males and 60 females,
ranging in age from 21 to 75 years (mean age= 44 years).
Patients were examined in four subgroups according to their age (Table 1).
A control group for all of the age groups was not formed.
However,
we examined three asymptomatic patients (with no neurogenic claudication) without and with axial loading (Table 2).
MRI was performed on a 1.5 Tesla system (Gyroscan Intera,
Philips Medical Systems,
Best,
and Holland) using a spine array coil.
All cases were first examined using routine lumbar MR imaging in the supine position with slight flexion in the hips and knees.
In this position,
T1 and T2 weighted axial and sagittal plans of the same sequences were performed during axial loading applied to the spine.
All cases were examined without and with axial loading MRI at L4-5,
and L5-S1 levels (Figure 1).
The axial load was applied for 5 minutes,
which was easily tolerated by the patients and no need of using additional analgesics.
The axial loading procedure was performed using a non-magnetic compression device (DynaWell L-spine; DynaWell Int.
AB,
Billdal,
Sweden) inclucing a specific patient vest,
straps,
cords,
a footplate and a compression mechanism (Figure 2).
The feet were placed against the footplate of the compression device.
The straps on the vest were tightened.
Two adjustable cords on the opposite side of the vest were attached to the compression device.
Axial compression was applied to the spine by tightening the cords.
The force of compression can be adjusted by the compression device and can be measured by the sensors in the foot plate.
The chosen load was 50% of the subject's body weight,
which was distributed equally to both legs.
Slices at the same level were used to measure the axial T2-weighted images of the routine supine and axial loaded MRI.
The selected image was the image in which the dural sac cross sectional area (DSCA) appeared to be the smallest at each disc level of L4-5 to L5-S1.
All measurements of the DSCA were performed using T2-weighted axial imaging in routine supine and axial loaded MRI.
The OsiriX imaging software (version 6.0.2; Bernex,
Switzerland) was used to measure the DSCA without and with the axial load MRI images.
Relative stenosis was accepted as a DSCA of less than 100 mm2 and absolute stenosis less than 75 mm2 (Figure 3,4).
The DSCA was assumed to be significantly reduced,
if it decreased by more than 15mm SQ during axial loading.