Background:Low back pain (LBP) is a prevalent condition, with most individuals experiencing it at some point. Magnetic resonance imaging (MRI) is the primary imaging modality for LBP diagnostics, enab...

BACKGROUND AND PURPOSE: 18F-FDG PET/CT and conventional MRI are common first-line imaging modalities for assessment of osseous spinal lesions. Dynamic contrast-enhanced MR imaging (DCE-MRI) is an advanced technique that quantifies vascular perfusion parameters like vessel permeability ( Ktrans ) and plasma volume ( Vp ), which are markers of viable tumor. Although DCE-MRI and 18F-FDG PET/CT are individually recognized for tumor detection, comparisons between Vp and PET-obtained maximum standardized uptake value (SUVmax) have not been performed. This study evaluates the concordance between Vp and SUVmax in detecting pathologically confirmed, nontreated osseous spinal metastases. MATERIALS AND METHODS: Nontreated osseous spinal metastases biopsy-confirmed between February 2015 and January 2022 with available DCE-MRI and 18F-FDG PET/CT scans were retrospectively analyzed. Exclusion criteria included radiation therapy near lesions and therapy between scans. Mean Ktrans and Vp were obtained from DCE-MRI via the extended Tofts model and compared with PET SUVmax values. A Vp threshold of 2.10 and PET SUVmax thresholds of 2.00, 2.50, and 4.00 were used to detect metastases. Agreement was assessed via McNemar tests (α = .05). RESULTS: Eighty-five metastases across 69 patients (mean age: 64.15 [SD, 12.13] years; 35 men) were evaluated. At an SUVmax threshold of 2.00, Vp demonstrated a high agreement of 81.18% (69/85) with SUVmax in detecting biopsy-confirmed tumors. Agreement with other SUVmax thresholds was lower: 67.06% (57/85) for an SUVmax of 2.50 and 48.24% (41/85) for an SUVmax of 4.00, as expected. Vp identified the most metastases at 84, compared with 68, 56, and 40 for SUVmax thresholds of 2.00, 2.50, and 4.00, respectively ( P < .001). CONCLUSIONS: Vp and SUVmax showed agreement in detecting osseous spinal metastases. However, when common thresholds for these metrics are applied, Vp exceeds SUVmax in identifying viable tumor. DCE-MRI plays a crucial role in detecting spinal metastases and, in some instances, more accurately detects biopsy-positive lesions compared with 18F-FDG PET/CT. DCE-MRI : dynamic contrast-enhanced MR imaging FA : flip angle IQR : interquartile range Ktrans : vessel permeability RT : radiation therapy SUV : standardized uptake value Vp : plasma volume