Diffusion tensor imaging with fiber tracking provides a valuable quantitative and clinical evaluation for compressed lumbosacral nerve roots: a systematic review and meta-analysis

Longitudinal DTI analysis of microstructural changes in lumbar nerve roots following Interspinous process device placement

Diffusion tensor imaging (DTI) and its parameters such as fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD) are increasingly being used to assess peripheral nerve integrity alongside nerve conduction studies. This pilot study aims to compare DTI values of lumbar spinal nerve roots before (T0) and after (T1) treatment with an interspinous process device (IPD). Seven patients (5 females, 2 males; mean age: 68) suffering from neurogenic claudication and lumbar spinal canal and foraminal stenosis were evaluated. Visual Analog Scale (VAS) for perceived pain, Oswestry Disability Index (ODI), and DTI parameters were assessed between T0 and T1. No significant difference in FA was found in treated roots, while MD (p = 0.0015), RD (p = 0.0032), and AD (p = 0.0221) were significantly altered. At untreated levels, all DTI parameters showed highly significant differences (p < 0.0001) between T0 and T1. In treated roots, FA values significantly increased in the intraforaminal segment(p = 0.0229), while MD(p = 0.0124), AD(p = 0.0128), and RD (p = 0.0143) values decreased in the pre-foraminal segment. In untreated roots, FA significantly increased in pre(p = 0.0039)and intraforaminal(p = 0.0003) segments, and MD, AD, and RD decreased in all segments (p < 0.0001). VAS (p < 0.0001) also decreased between T0 and T1. This pilot study aims to clarify the biomechanical impact of interspinous spacers through microstructural analysis of both treated and adjacent untreated nerve roots. To our knowledge, no studies have examined the short- to medium-term changes in DTI values of lumbar nerve roots before and after IPD placement, or compared changes between treated and untreated roots.

Clinical Value and Reliability of Quantitative Assessments of Lumbosacral Nerve Root Using Diffusion Tensor and Diffusion Weighted MR Imaging: A Systematic Review

BACKGROUND

Lumbosacral radicular pain diagnosis remains challenging. Diffusion tensor imaging (DTI) and diffusion weighted imaging (DWI) have potential to quantitatively evaluate symptomatic nerve root, which may facilitate diagnosis.

PURPOSE

To determine the ability of DTI and DWI metrics, namely fractional anisotropy (FA) and apparent diffusion coefficient (ADC), to discriminate between healthy and symptomatic lumbosacral nerve roots, to evaluate the association between FA and ADC values and patient symptoms, and to determine FA and ADC reliability.

STUDY TYPE

Systematic review.

SUBJECTS

Eight hundred twelve patients with radicular pain with or without radiculopathy caused by musculoskeletal-related compression or inflammation of a single, unilateral lumbosacral nerve root and 244 healthy controls from 29 studies.

FIELD STRENGTH/SEQUENCE

Diffusion weighted echo planar imaging sequence at 1.5 T or 3 T.

ASSESSMENT

An extensive systematic review of the literature was conducted in Embase, Scopus, and Medline databases. FA and ADC values in symptomatic and contralateral lumbosacral nerve roots were extracted and summarized, together with intra- and inter-rater agreements. Where available, associations between DWI or DTI parameters and patient symptoms or symptom duration were extracted.

STATISTICAL TESTS

The main results of the included studies are summarized. No additional statistical analyses were performed.

RESULTS

The DTI studies systematically found significant differences in FA values between the symptomatic and contralateral lumbosacral nerve root of patients suffering from radicular pain with or without radiculopathy. In contrast, identification of the symptomatic nerve root with ADC values was inconsistent for both DTI and DWI studies. FA values were moderately to strongly correlated with several symptoms (eg, disability, nerve dysfunction, and symptom duration). The inter- and intra-rater reliability of DTI parameters were moderate to excellent. The methodological quality of included studies was very heterogeneous.

DATA CONCLUSION

This systematic review showed that DTI was a reliable and discriminative imaging technique for the assessment of symptomatic lumbosacral nerve root, which more consistently identified the symptomatic nerve root than DWI. Further studies of high quality are needed to confirm these results.

EVIDENCE LEVEL

N/A TECHNICAL EFFICACY: Stage 2.

Nerve abnormalities in lumbar disc herniation: A systematic review and meta-analysis of diffusion tensor imaging

PURPOSE

The purpose of this study was to examine the values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in diffusion tensor imaging (DTI) for diagnosing patients with nerve impairment due to lumbar disc herniation (LDH).

METHODS

A literature search of databases (PubMed, Web of Science, Cochrane Library and Embase) was systematically performed to identify articles published before September 2021 that were relevant to this study. FA and ADC estimates of compressed nerve roots due to LDH and healthy controls in the same segment were compared, with either fixed or random effects models selected according to I2 heterogeneity. Additionally, subgroup analysis, sensitivity analysis, potential publication bias analysis and meta-regression analysis were also performed.

RESULTS

A total of 369 patients with LDH from 11 publications were included in this meta-analysis. The results showed significantly lower FA values (Weighted Mean Difference (WMD): -0.08, 95% confidence interval (CI): -0.09 to -0.07, P ≤ 0.001, I2 = 87.6%) and significantly higher ADC values (WMD: 0.25, 95% CI: 0.20 to 0.30, P ≤ 0.001, I2 = 71.4%) of the nerve on the compressed side due to LDH compared to the healthy side. Subgroup analysis indicated that different countries and magnetic field strengths may be associated with higher heterogeneity. Furthermore, meta-regression analysis further revealed that segment and field strength did not have a significant effect on the results, regardless of the FA or ADC values. Contrastingly, in FA, the year of publication, country, b value and directions showed an effect on the results.

CONCLUSIONS

This meta-analysis showed a significant decrease in FA and a significant increase in ADC in patients with nerve damage due to LDH. The results favourably support the presence of nerve impairment in patients with LDH.

Role of MR Neurography for Evaluation of the Lumbosacral Plexus: A Scoping Review

Purpose

MR neurography (MRN) is an imaging technique optimized to visualize the peripheral nerves. This review aimed to discover an optimized protocol for MRN of the lumbosacral plexus (LSP) and identify evidence for the clinical benefit of lumbosacral plexopathies.

Materials and Methods

We performed a systematic search of the two medical databases until September 2021. 'Magnetic resonance imaging', 'lumbosacral plexus', 'neurologic disease', or equivalent terms were used to search the literature. We extracted information on indications, MRN protocols for LSP, and clinical efficacy from 55 studies among those searched.

Results

MRN of the LSP is useful for displaying the distribution of peripheral nerve disease, guiding perineural injections, and assessing extraspinal causes of sciatica. Three-dimensional short-tau inversion recovery turbo spin-echo combined with vascular suppression is the mainstay of MRN.

Conclusion

Future work on the MRN of LSP should be directed to technical maturation and clinical validation of efficacy.

Comparative radiological outcomes and complications of sacral-2-alar iliac screw versus iliac screw for sacropelvic fixation

PURPOSE

To compare the outcomes of sacropelvic fixation (SPF) using sacral-2-alar iliac (S2AI) screw with SPF using iliac screw (IS).

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane Central Register of Controlled Trials and Scopus was performed for comparative studies between S2AI and IS for SPF. Two independent investigators selected qualified studies and extracted data indispensably. With 95% confidence intervals (CI), the odds ratio (OR) was applied to dichotomous outcomes and standardized mean difference (SMD) was applied to continuous outcomes for each item.

RESULTS

We included data from thirteen studies involving 722 patients (S2AI, 357 patients; IS, 365 patients). In the pediatric population, the S2AI group had a smaller pelvic obliquity (PO) than the IS group at final follow-up (SMD, - 0.38; 95% CI, - 0.72 to - 0.04). Patients who underwent S2AI screws showed reduced rates of re-operation (S2AI, 13%; IS, 28%), implant failure (S2AI, 12%; IS, 26%) [screw loosening (S2AI, 8%; IS, 20%); screw breakage (S2AI, 2%; IS, 12%)], implant prominence (S2AI, 2%; IS, 14%), pseudarthrosis (S2AI, 3%; IS, 15%), wound infection (S2AI, 8%; IS, 22%) and less blood loss (S2AI, 2035.4 ml; IS, 2708.4 ml).

CONCLUSION

Radiological outcomes indicate an effective maintenance of the correction and arrest of progression of deformity by S2AI, which is equal or better than IS. SPF with S2AI screw has obviously lower incidence of postoperative complications and less blood loss. Given these advantages, the S2AI screw seems to be a beneficial alternative to IS.

3D-printed drill guide template, a promising tool to improve pedicle screw placement accuracy in spinal deformity surgery: A systematic review and meta-analysis

PURPOSE

This study aimed to compare the pedicle screw placement accuracy and surgical outcomes between 3D-printed (3DP) drill guide template technique and freehand technique in spinal deformity surgery.

METHODS

A comprehensive systematic literature search of databases (PubMed, Embase, Cochrane Library, and Web of Science) was conducted. The meta-analysis compared the pedicle screw placement accuracy and other important surgical outcomes between the two techniques.

RESULTS

A total of seven studies were included in the meta-analysis, comprising 87 patients with 1384 pedicle screws placed by 3DP drill guide templates and 88 patients with 1392 pedicle screws placed by freehand technique. The meta-analysis results revealed that the 3DP template technique was significantly more accurate than the freehand technique to place pedicle screws and had a higher rate of excellently placed screws (OR 2.22, P < 0.001) and qualifiedly placed screws (OR 3.66, P < 0.001), and a lower rate of poorly placed screws (OR 0.23, P < 0.001). The mean placement time per screw (WMD-1.99, P < 0.05), total screw placement time (WMD-27.86, P < 0.001), and blood loss (WMD-104.58, P < 0.05) were significantly reduced in the 3DP template group compared with the freehand group. Moreover, there was no significant statistical difference between the two techniques in terms of the operation time and correction rate of main bend curve.

CONCLUSIONS

This study demonstrated that the 3DP drill guide template was a promising tool for assisting the pedicle screw placement in spinal deformity surgery and deserved further promotion.