Quantitative MRI analysis of the surface area, signal intensity and MRI index of the central bright area for the evaluation of early adjacent disc degeneration after lumbar fusion

Purpose

The aim of this study was to evaluate early ASD at short-term follow-up in fused and unoperated patients with degenerative disc disease, using quantitative magnetic resonance imaging (MRI) analysis of the area, signal intensity and their product, i.e., MRI index of the central bright area of the disc as well as measures of intervertebral disc height and Pfirrmann grading scale. The further purpose was to determine whether fusion accelerates ASD compared with non-surgical treatment in short-term follow-up.

Methods

One hundred and eight chronic low back patients diagnosed as L4/L5 degeneration undertook either one-level instrumented posterior lumbar interbody fusion or conservative treatment. They were followed up for about 1?year. Finally 46 fused and 45 conservatively treated patients with MRI follow-up were included. Pre- and post-treatment MRIs were compared to determine the progression of disc degeneration at the two cranial adjacent segments.

Results

The area, signal intensity and MRI index of the central bright area of the adjacent discs decreased in the operated and unoperated groups from pre-treatment to follow-up, except for an insignificant decrease of signal intensity at the second adjacent segment in the unoperated group. The changes in these parameters were statistically greater at the first than the second adjacent segment in the fused group, but not in the unoperated group. And the changes in the fused group were more pronounced than those at both neighbouring levels in the unoperated group. However, the Pfirrmann grading scale and intervertebral disc height did not detect any changes at adjacent discs in either group.

Conclusions

Decrease in the parameters of quantitative MRI analysis indicated early degeneration at discs adjacent to lumbar spinal fusion. Fusion had an independent effect on the natural history of ASD during short-term follow-up. Continued longitudinal follow-up is required to determine whether these MRI changes lead to pathologic changes.     

Determination of the time for maximal response to neoadjuvant hormone therapy for prostate cancer using magnetic resonance with spectroscopy (MRSI) and dynamic contrast enhancement (DCEMR)

PurposeTo determine the time-dependent metabolic and angiogenic changes that occur in prostate cancer (CaP) during neoadjuvant hormone therapy (HT), using a combination of MRSI and DCEMR analysis.Materials and methodsThis is a prospective study on a population of non-metastatic CaP submitted to neoadjuvant HT prior to radiation therapy. All cases homogeneously received a 6-month period of neoadjuvant HT using leuprorelin acetate 7.5 mg every 28 days. In all cases, a MRSI/DCEMR study was performed at baseline (pretreatment) and at regular intervals (4, 12, 24 weeks) during HT. Serum PSA was measured at baseline and at the same intervals (4, 12, 24 weeks). All MRI examinations were performed on a commercially available 3 T scanner.ResultsThere was a significant ( P < 0.01) time-dependent loss of all prostate metabolites during HT. In regions of CaP no significant variation in the absolute value of metabolites was reported at 1-month interval and a higher variation was observed at 24-week compared with 12-week interval. A complete metabolic atrophy was a common feature (30%) at a 24-week interval of HT, but not at short (4-week 0%), and lower at an intermediate interval (12-week 10%). At DCEMR, onset time and time to peak parameters significantly (P < 0.05) increased at 12- and 24-week intervals.ConclusionsTo individualize neoadjuvant HT courses prior to definitive treatment, the combination of MRSI and DCEMR may represent a valid noninvasive method, and the addition to PSA data could be used to better assess the time-dependent efficacy of HT in our patients.