Assessing bone density on MRI: comparison between routine MRI sequences and DEXA scans

PURPOSE

Magnetic Resonance Imaging (MRI) is frequently utilised to aid in the comprehensive assessment of back pain, while dual-energy x-ray absorptiometry (DEXA) is the gold standard test for the assessment of bone density. Assessing bone density on MRI could reduce costs and avoid exposing patients to ionising radiation. The aim of this paper is to investigate whether the relative signal intensity of vertebral bodies compared to other structures can detect osteoporosis on MRI.

METHODS

100 patients that had undergone both a lumbar spine MRI and a DEXA scan were identified. The T1 and T2 signal intensity of L1-L4 vertebral bodies (VB), cerebro-spinal fluid (CSF), and psoas muscle were measured within a 1-cm2 region of interest (ROI), and the signal intensity ratios were calculated. The ratios were stratified as normal, osteopenic, or osteoporotic based on DEXA T-scores.

RESULTS

The T1 VB /T1 CSF ratio was significantly higher in the osteoporotic group than the normal and osteopenic groups (p < 0.001). The T1 VB /T1 CSF ratio had excellent discrimination (AUC = 0.841) for the presence of osteoporosis. The Pearson correlation coefficient between the DEXA T-score and the T1 VB/T1 CSF ratio was -0.474 (p < 0.001). The intra-observer (ICC = 0.910, 95% CI = 0.757-0.966) and inter-observer reliability (ICC = 0.927, 95% CI = 0.824-0.970) were excellent. In our cohort, a T1 VB / T1 CSF ratio of greater than 4 is 66.7% sensitive but 90.0% specific for the presence of osteoporosis.

CONCLUSION

A high T1 VB/T1 CSF ratio suggests osteoporosis on MRI. Prospective validation is needed to confirm these findings.

BioGlue® induced granuloma causing symptomatic spinal cord compression: a late complication

BioGlue® is an inert, bioadhesive surgical substance commonly used in spinal surgery to aid dural closure. The authors describe two cases in which the use of BioGlue® caused a local reaction culminating in the formation of a granuloma that caused cord compression several years after surgery in one case in which a second operation was required to relieve cord compression and remove the foreign material. In the other case spontaneous resolution occurred. To our knowledge these are the first reports of delayed spinal cord compression secondary to BioGlue®-induced granuloma. We recommend judicious use of this substance.

Is endoscopic third ventriculostomy superior to shunts in patients with non-communicating hydrocephalus? A systematic review and meta-analysis of the evidence

BACKGROUND

Endoscopic third ventriculostomy (ETV) and shunts are both utilized in the treatment of non-communicating hydrocephalus. The objective of this study was to review the evidence comparing the effectiveness of these two techniques.

METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL) and Medline databases were searched between 1990 and August 2012. We included all studies comparing the failure rate of patients with non-communicating hydrocephalus treated with ETV and shunts. Two authors (HJM and FTR) appraised quality and extracted data independently.

RESULTS

Of 313 articles identified, 12 were selected for further review. Of these, 6 were included for qualitative analysis, and 5 for quantitative analysis (n = 504). ETV was associated with a non-statistically significant reduction in failure using the random-effects model (OR 0.58, 95 % CI 0.29-1.13).

CONCLUSIONS

Both ETV and shunts are associated with a relatively high failure rate. At present there is insufficient proof to unequivocally recommend one mode of treatment above the other. However, there is some evidence that ETV may confer long-term survival advantage over shunts in the treatment of non-communicating hydrocephalus, particularly in patients with certain aetiologies such as aqueductal stenosis. Prospective randomized controlled trials are currently underway and may provide more robust evidence to answer this important question and better guide future management.