Objective To test the equivalence for clinical effectiveness between microdecompression and laminectomy in patients with central lumbar spinal stenosis. Design Multicentre observational study. Setting Prospective data from the Norwegian Registry for Spine Surgery. Participants 885 patients with central stenosis of the lumbar spine who underwent surgery at 34 Norwegian orthopaedic or neurosurgical departments. Patients were treated from October 2006 to December 2011. Interventions Laminectomy and microdecompression. Main outcome measures The primary outcome was change in Oswestry disability index score one year after surgery. Secondary endpoints were quality of life (EuroQol EQ-5D), perioperative complications, and duration of surgical procedures and hospital stays. A blinded biostatistician performed predefined statistical analyses in unmatched and propensity matched cohorts. Results The study was powered to detect a difference between the groups of eight points on the Oswestry disability index at one year. 721 patients (81%) completed the one year follow-up. Equivalence between microdecompression and laminectomy was shown for the Oswestry disability index (difference 1.3 points, 95% confidence interval −1.36 to 3.92, P<0.001 for equivalence). Equivalence was confirmed in the propensity matched cohort and full information regression analyses. No difference was found between groups in quality of life (EQ-5D) one year after surgery. The number of patients with complications was higher in the laminectomy group (15.0% v 9.8%, P=0.018), but after propensity matching for complications the groups did not differ (P=0.23). The duration of surgery for single level decompression was shorter in the microdecompression group (difference 11.2 minutes, 95% confidence interval 4.9 to 17.5, P<0.001), but after propensity matching the groups did not differ (P=0.15). Patients in the microdecompression group had shorter hospital stays, both for single level decompression (difference 1.5 days, 95% confidence interval 1.7 to 2.6, P<0.001) and two level decompression (0.8 days, 1.0 to 2.2, P=0.003). Conclusion At one year the effectiveness of microdecompression is equivalent to laminectomy in the surgical treatment of central stenosis of the lumbar spine. Favourable outcomes were observed at one year in both treatment groups. Trial registration ClinicalTrials.gov NCT02006901.

Background: Most of the existing hyperpolarized (HP) ¹³C MRI analyses use univariate rate maps of pyruvate-to-lactate conversion (k_PL), and radiomic-style multiparametric models extracting complex, higher-order features remain unexplored. Purpose: To establish a multivariate framework based on whole abdomen/pelvis HP ¹³C-pyruvate MRI and evaluate the association between multiparametric features of metabolism (MFM) and clinical outcome measures in advanced and metastatic prostate cancer. Methods: Retrospective statistical analysis was performed on 16 participants with metastatic or local-regionally advanced prostate cancer prospectively enrolled in a tertiary center who underwent HP-pyruvate MRI of abdomen or pelvis between November 2020 and May 2023. Five patients were hormone-sensitive and eleven were castration-resistant. GMP-grade [1-¹³C]pyruvate was polarized using a 5T clinical-research DNP polarizer, and HP MRI used a set of flexible vest-transmit, array-receive coils, and echo-planar imaging sequences. Three basic metabolic maps (k_PL, pyruvate summed-over-time, and mean pyruvate time) were created by semi-automatic segmentation, from which 316 MFMs were extracted using an open-source, radiomic-compliant software package. Univariate risk classifier was constructed using a biologically meaningful feature (k_PL,median), and the multivariate classifier used a two-step feature selection process (ranking and clustering). Both were correlated with progression-free survival (PFS) and overall survival (OS) (median follow-up = 22.0 months) using Cox proportional hazards model. Results: In the univariate analysis, patients harboring tumors with lower-k_PL,median had longer PFS (11.2 vs. 0.5 months, p < 0.01) and OS (NR vs. 18.4 months, p < 0.05) than their higher-k_PL,median counterparts. Using a hypothesis-generating, age-adjusted multivariate risk classifier, the lower-risk subgroup also had longer PFS (NR vs. 2.4 months, p < 0.002) and OS (NR vs. 18.4 months, p < 0.05). By contrast, established laboratory markers, including PSA, lactate dehydrogenase, and alkaline phosphatase, were not significantly associated with PFS or OS (p > 0.05). Key limitations of this study include small sample size, retrospective study design, and referral bias. Conclusions: Risk classifiers derived from select multiparametric HP features were significantly associated with clinically meaningful outcome measures in this small, heterogeneous patient cohort, strongly supporting further investigation into their prognostic values.

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