Reliability and accuracy of time-resolved contrast-enhanced magnetic resonance angiography in hypervascular spinal
Kévin Premat1, Eimad Shotar2, Robert Burns2
1Sorbonne University, AP-HP, Pitié Salpêtrière - Charles Foix Hospital, Department of Neuroradiology, F75013, Paris, France. kevin.premat@aphp.fr.
Objectives:
Preoperative embolization of hypervascular spinal metastases (HSM) is efficient to reduce perioperative bleeding. However, intra-arterial digital subtraction angiography (IA-DSA) must confirm the hypervascular nature and rule out spinal cord arterial feeders. This study aimed to evaluate the reliability and accuracy of time-resolved contrast-enhanced magnetic resonance angiography (TR-CE-MRA) in assessing HSM prior to embolization.
Methods:
All consecutive patients referred for preoperative embolization of an HSM were prospectively included. TR-CE-MRA sequences and selective IA-DSA were performed prior to embolization. Two readers independently reviewed imaging data to grade tumor vascularity (using a 3-grade and a dichotomized "yes vs no" scale) and identify the arterial supply of the spinal cord. Interobserver and intermodality agreements were estimated using kappa statistics.
Results:
Thirty patients included between 2016 and 2019 were assessed for 55 levels. Interobserver agreement was moderate (κ = 0.52; 95% CI [0.09-0.81]) for TR-CE-MRA. Intermodality agreement between TR-CE-MRA and IA-DSA was good (κ = 0.74; 95% CI [0.37-1.00]). TR-CE-MRA had a sensitivity of 97.9%, a specificity of 71.4%, a positive predictive value of 95.9%, a negative predictive value of 83.3%, and an overall accuracy of 94.6%, for differentiating hypervascular from non-hypervascular SM. The arterial supply of the spine was assessable in 2/30 (6.7%) cases with no interobserver agreement (κ < 0).
Conclusions:
TR-CE-MRA can reliably differentiate hypervascular from non-hypervascular SM and thereby avoid futile IA-DSAs. However, TR-CE-MRA was not able to evaluate the vascular supply of the spinal cord at the target levels, thus limiting its scope as a pretherapeutic assessment tool.
Key Points:
• TR-CE-MRA aids in distinguishing hypervascular from non-hypervascular spinal metastases. • TR-CE-MRA could avoid one-quarter of patients referred for HSM embolization to undergo futile conventional angiography. • TR-CE-MRA's spatial resolution is insufficient to replace IA-DSA in the pretherapeutic assessment of the spinal cord vascular anatomy.
