Reliability and accuracy of time-resolved contrast-enhanced magnetic resonance angiography in hypervascular spinal metastases prior embolization

Diagnostic performance of computed tomography-digital subtraction angiography and conventional magnetic resonance imaging for evaluating the vascularity of osseous spinal tumors

BACKGROUND AND PURPOSE

Patients with hypervascular spinal tumors may have severe blood loss during tumor resection, which increases the risks of perioperative morbidity and mortality. However, the preoperative evaluation of tumor vascularity may be challenging; moreover, the reliability of the data obtained in conventional preoperative noninvasive imaging is debatable. In this study, we compared conventional magnetic resonance imaging (MRI) and subtraction computed tomography angiography (CTA) in terms of their performance in vascularity evaluation. The catheter digital subtraction angiography (DSA) technique was used as a reference standard.

METHODS

This study included 123 consecutive patients with spinal tumor who underwent subtraction CTA, catheter DSA, and subsequent surgery between October 2015 and October 2021. Data regarding qualitative and semiquantitative subtraction CTA parameters and conventional MRI signs were collected for comparison with tumor vascularity graded through catheter DSA. The diagnostic performance of qualitative CTA, quantitative CTA, and conventional MRI in assessing spinal tumor vascularity was analyzed.

RESULTS

Qualitative subtraction CTA was the best noninvasive imaging modality in terms of diagnostic performance (area under the receiver operating characteristic curve [AUROC], 0.95). Quantitative CTA was relatively inferior (AUROC, 0.87). MRI results had low reliability (AUROC, 0.51 to 0.59). Intratumoral hemorrhage and prominent foraminal venous plexus were found to be the specific signs for hypervascularity (specificity 93.2%).

CONCLUSIONS

Qualitative subtraction CTA offers the highest diagnostic value in evaluating spinal tumor vascularity, compared to quantitative CTA and MRI. Although conventional MRI may not be a reliable approach, certain MRI signs may have high specificity, which may be crucial for assessing spinal tumor vascularity.

Efficacy of preoperative embolization for metastatic spinal tumor surgery using angiographic vascularity assessment

OBJECTIVES

Preoperative embolization (PE) for metastatic spinal tumors is a method of minimizing intraoperative blood loss during aggressive surgery. This study specified angiographic standards and investigated the influence of these and other factors on blood loss in patients with spinal metastases and various pathologies.

METHODS

The cohort comprised 126 consecutive patients receiving PE from 2015 to 2021. Their clinical, surgical, and angiographic characteristics were reviewed. Standard angiographic grading was used for vascularity assessment. Degree of embolization was divided into complete (≥ 90%), near complete (67 to < 90%), and partial (< 67%). Logistic regression analysis was used to investigate factors predictive of massive blood loss (> 2500 mL). A proportional odds model was used to assess factors predictive of the degree of embolization.

RESULTS

Mean intraoperative blood loss was 1676 mL. Among the patients, 62 had hypervascular tumors and 64 had nonhypervascular tumors, according to the angiographic classification. Intraoperative blood loss differed significantly with embolization degree, both overall (p < 0.001) and in the hypervascular and nonhypervascular groups (p = 0.01 and 0.03). Angiographic hypervascularity, spinal metastasis invasiveness index, and embolization degree were significant predictors of massive blood loss in univariate analysis, but only embolization degree was significant in multivariate analysis. Only the presence of the radiculomedullary artery at the target level was significant in both the univariate and multivariate analyses for embolization degree.

CONCLUSIONS

In addition to pathological classification, angiographic vascularity assessment is valuable. Although complete embolization is a reasonable goal, it is challenging to achieve in cases of visible radiculomedullary artery.

KEY POINTS

• Angiography has a supplementary role in vascularity assessment for spinal metastatic surgery. • Better embolization degree is associated with less intraoperative blood loss in both angiographic hypervascular and nonhypervascular groups. • Presence of radiculomedullary artery in the target level causes worse embolization outcome.

Peripheral vascular lesions in adults referred to MRI/MRA: Multivariable analysis of imaging features to help differentiate benign vascular anomalies from malignancies

PURPOSE

Symptomatic peripheral vascular lesions in adults are often clinically diagnosed as benign vascular anomalies and may receive MRI/MRA for pre-treatment vascular mapping. Malignant neoplasms are difficult to distinguish from benign vascular anomalies on MRI/MRA. This study was performed to determine if there are imaging signs that can distinguish malignancies from benign vascular anomalies in adults imaged with MRI/MRA.

MATERIALS AND METHODS

A radiology database was retrospectively searched for ISSVA classification terms in MRI/MRA reports from 1/1/2002-1/1/2019. Adult patients (n = 50, 52 corresponding lesions) with contrast-enhanced MRI/MRA, peripheral soft tissue based lesion (s), and available pathology or long-term (>1 year) imaging follow-up were included. MRI/MRA images were reviewed by 3 readers for the following lesional characteristics: morphology (marginal lobulation, internal septations, distinct soft tissue mass), peri-articular location, T2-weighted characteristics (hyperintensity, heterogeneity, perilesional edema, and adjacent triangular T2-peaks), bulk fat, hemorrhage, enhancement pattern (peripheral, diffuse, or absent), neovascularity, low-flow venous malformation type enhancement, arterial enhancement within 6 s, enhancement curve (progressive, plateau, or washout), measured size, and multifocality. The MRI/MRA features' associated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. To identify factors predictive of malignancy, a two-stage multivariable analysis was performed.

RESULTS

23% (12/52) of the lesions, corresponding to 22% (11/50) of the patients, were malignant neoplasms. No single imaging feature reliably predicted malignancy (PPV ≤ 60%). Absence of distinct soft tissue mass excluded malignancy (NPV 100%). Multivariate analysis derived a summary score based on the five strongest predictors of malignancy: adjacent T2 peaks, age ≥ 70 years, distinct soft tissue mass, lesion size ≥ 5 cm, and absence of septations. A score ≥ 3 resulted in sensitivity of 92% and specificity of 85%.

CONCLUSION

Extremity MRI/MRA rarely differentiates malignant from benign soft-tissue vascular tumors in adults. However, MRI/MRA can suggest malignancy when patient age and multiple imaging features are considered. Periodic clinical follow-up after the planned endovascular or operative procedure should be performed to avoid missing a malignancy.

The role of percutaneous transarterial embolization in the management of spinal bone tumors: a literature review

PURPOSE

Spinal bone tumors include a heterogeneous broad of primary or metastatic lesions that may present as incidental findings or manifest with painful symptoms and pathological fractures. Optimal management of spine bone lesions is often difficult and treatment algorithms are usually solidly based on surgery. We aimed to evaluate the contribution of trans-arterial embolization in this field, with particular attention to the procedure efficacy, technical difficulties and complications.

METHODS

We present a literature review on the role of trans-arterial embolization in the management of spinal bone tumors, both primary and metastatic, evaluating its contribution as preoperative treatment, palliative procedure and standalone curative strategy.

RESULTS

Trans-arterial embolization provides an important contribution to reducing surgery hemorrhagic risks, offering a better visualization of the operating field, and possibly increasing tumor susceptibility to chemotherapy or radiation therapy. Nonetheless, it plays an important part in pain palliation, with the unquestionable advantage of being easily repeatable in case of necessity. Its curative role as a standalone therapy is still subject of debate, and at the present time, satisfactory results have been recorded only in the treatment of aneurysmal bone cysts.

CONCLUSION

Percutaneous trans-arterial embolization has established as a highly useful minimally invasive procedure in the management of spinal bone lesions, particularly as adjuvant preoperative therapy and palliative treatment.