Applicative value of T2 mapping in evaluating lumbosacral nerve root injury induced by lumbosacral disc herniation.

BACKGROUND: To alleviate the damage caused by nerve root entrapment mediated by lumbosacral disc herniation (LDH), an imaging method that allows quantitative evaluation of the lumbosacral nerve injury is necessary. PURPOSE: To investigate the diagnostic value of magnetic resonance (MR) T2 mapping in nerve root injury caused by LDH. MATERIAL AND METHODS: A total of 70 patients with unilateral sciatic nerve pain and 35 healthy volunteers were divided into three groups: LDH with nerve root entrapment; LDH without nerve root entrapment; and 35 healthy volunteers. All participants underwent 3.0-T MR with T1-weighted (T1W) imaging, T2-weighted (T2W) imaging, and T2-mapping images. T2 was measured and observed with the left and right nerve roots of the L4-S1 segments in healthy volunteers; the differences between the three groups were compared. T2 and the relaxation rate of nerve root injury were analyzed. RESULTS: T2 showed significant differences among the three groups (F = 89.494; P = 0.000), receiver operating characteristic curve revealed that the T2 relaxation threshold was 79 ms, the area under curve (AUC) area was 0.86, sensitivity was 0.77, and specificity was 0.74; the T2 relaxation rate was 1.06, the AUC area was 0.88, sensitivity was 0.74, and specificity was 0.85. CONCLUSION: T2 mapping could quantitatively evaluate the nerve root injury with lumbar disc degeneration. Hence, it can be used for the clinical evaluation of nerve root entrapment caused by LDH.

Diagnostic test of dynamic computed tomography in early gastrointestinal lymphoma and precancerous lesions.

Background: In recent years, with the development of imaging technology, the accurate diagnosis of precancerous lesions of digestive system and early lymphoma has attracted wide attention in the medical field. Methods: In this study, 82 patients with gastrointestinal diseases, including 32 patients with early gastrointestinal lymphoma and 50 patients with gastrointestinal precancerous lesions, underwent dynamic contrast-enhanced computed tomography (CT) scanning. The difference (δ1, δ2) and ratio (Q1, Q2) of density between arterial phase, portal phase and plain scan were measured and compared, and the receiver operating characteristic (ROC) curve of the subjects was drawn. Results: The results showed no statistically significant differences in the general condition of patients or a difference for the results of the arterial phase δ1 and Q1 between the two groups (P>0.05). However, the portal venous phase δ2 and Q2 in the early lymphoma group and in precancerous lesion group were 29.50±6.05, 41.55±10.10 Hounsfield units (HU), and 1.70±0.05, 2.06±0.31, respectively. The area under the ROC curve (AUC) values for δ2 and Q2 to identify the two diseases were 0.755 and 0.878, respectively. When δ2 and Q2 were 35.63 and 1.86 HU, the specificity was 89.60% and 67.50%, and sensitivity was 89.60% and 64.90%, respectively. When the two indexes, δ2 and Q2, were combined, the specificity and sensitivity of diagnosis were 98.99% and 56.80%, respectively. Conclusions: Dynamic contrast-enhanced CT can effectively distinguish early gastrointestinal lymphoma from precancerous lesions and improve the diagnostic accuracy.

In vivo DTI longitudinal measurements of acute sciatic nerve traction injury and the association with pathological and functional changes.

OBJECTIVE: To explore the feasibility of longitudinally measuring acute traction injury to the sciatic nerve using 1.5 T clinical MRI scanner of diffusion tensor imaging (DTI) and to analyze the associations of the measurements [regarding fractional anisotropy (FA), apparent diffusion coefficient (ADC), eigenvalue (λ|| and λ⊥)] with limb function and pathology. MATERIALS AND METHODS: Acute traction injuries to the sciatic nerve were created in the right hind limbs of 32 New Zealand white rabbits, the left hind limbs were chosen as sham operation nerves. MRI scans were performed at intervals from pre-operation through 8 weeks post-operation follow up. Scanning sequences included T2WI, STIR, and single shot spin echo DTI with single shot EPI acquisition (SE-DTI-SSEPI). Parameters of FA, ADC, axial diffusivity (λ||) and radial diffusivity (λ⊥) were then calculated from the DTI. The limb functions and pathologic changes were evaluated and compared. RESULTS: Diffusion Tensor Tractography (DTT) only revealed the proximal portion of the injured nerves 1-3 days after traction injury but did not reveal the nerve of the distal and traction portions at all. Nerve fibers of the distal and traction portions were not revealed by DTT until after the 1st week. They were elongated gradually and recovered almost to the normal at 8th week. The value of FA and λ⊥of the injured nerves, which varied in different portions, were significantly different between the traction injury nerves and the sham operation nerves, whereas the value of ADC and λ|| were not significantly different. The curve lines of FA value-time for the proximal, traction and distal portions of the injured nerve correlated well to the functional and pathological changes of the limb affected, while the DTI parameters did not change that much in the sham-operated nerves. CONCLUSIONS: DTI obtained on a 1.5 T clinical MRI scanner can demonstrate early abnormal changes following traction injury to the sciatic nerve in rabbits. The curve lines of FA-time and λ⊥-time for nerve traction injury are consistent with the pathological and functional changes of the limb affected. DTI may thus be a sensitive and reliable method to evaluate degeneration and regeneration of the nerve after traction injury.