Intratumoral Flow Void Diameter on Standard Magnetic Resonance Imaging: A Practical Marker of Vascularity in Metastatic Spinal Tumors.

Abstract

Massive intraoperative blood loss remains a major complication in metastatic spinal tumor surgery, and accurate assessment of tumor vascularity is essential for predicting bleeding risk. While digital subtraction angiography (DSA) is the gold standard for assessing tumor vascularity, the procedure is invasive and logistically demanding. Primary tumor type vascularity assessment offers a simpler alternative but is often inaccurate due to tumor heterogeneity. A reliable, noninvasive imaging marker could improve preoperative vascularity assessment. This study aimed to evaluate the diagnostic performance of intratumoral flow void (IFV) diameter on standard MRI for predicting tumor vascularity in metastatic spinal tumors, compared with primary tumor type classification, using DSA as the reference standard. Retrospective cohort study PATIENT SAMPLE: Data were collected from 134 patients who underwent total spondylectomy for an isolated spinal metastasis with preoperative MRI and DSA between 2010 and 2023. The primary outcome was hypervascularity, defined as an angiographic grade ≥3 on DSA. Sensitivity and specificity were calculated for both IFV diameter and primary tumor type assessments. The area under the receiver operating characteristic (ROC) curve was used to evaluate diagnostic accuracy for IFV diameter. IFV diameter was measured on standard MRI and correlated with angiographic grade using Spearman's rank correlation. A multivariable binary logistic regression analysis was conducted to identify independent predictors of hypervascular tumors (DSA grade ≥3). ROC curve analysis was performed to identify the optimal IFV diameter cutoff for predicting hypervascular tumors (DSA grade ≥3). Sensitivity and specificity were compared between IFV diameter and primary tumor type vascularity assessment. This study received no external funding. The authors declare no conflicts of interest. IFV diameter showed a strong correlation with angiographic grade (r = 0.73, p < 0.05), whereas primary tumor type vascularity assessment showed a moderate correlation (r = 0.39, p < 0.05). In multivariable binary logistic regression, IFV diameter remained independently associated with angiographic hypervascularity (adjusted OR 33.8, p < 0.001). ROC analysis identified 2.5 mm as the optimal IFV diameter cutoff for predicting hypervascularity, yielding a sensitivity of 78.0%, specificity of 97.6%, and AUC of 0.91. The primary tumor type vascularity assessment showed a sensitivity of 70.0% and specificity of 60.7%, demonstrating comparatively lower diagnostic performance. IFV diameter on standard MRI provides a reliable, noninvasive marker for evaluating tumor vascularity. A 2.5 mm cutoff facilitates preoperative bleeding risk stratification and supports intervention planning, especially in settings where DSA is not routinely available. Clinical study.