Low-field MR imaging of meningiomas including dynamic contrast enhancement study: evaluation of surgical and histopathologic characteristics

Abstract

Background and purpose: Risks associated with surgery of meningiomas, especially those located in the skull base, are influenced by tumor consistency and vascularity. The purpose of this study was to find out if vascularity, consistency, and histologic characteristics of meningioma can be predicted preoperatively by using low-field MR imaging, including dynamic imaging of contrast enhancement.

Materials and methods: Twenty-one patients (mean age, 56; range, 34-73 years; 16 women, 5 men) with meningioma requiring first surgery were imaged by a 0.23T scanner. Time to maximum enhancement, maximum enhancement, and maximum intensity increase were noted from the enhancement curve of dynamic imaging. Relative intensity of tumor in fluid-attenuated inversion recovery (FLAIR) and T2-weighted images was calculated. The neurosurgeon evaluated surgical bleeding and hardness of tumor on a visual analog scale. Histopathologic analysis included subtype, World Health Organization grade, mitotic activity, grades of progesterone receptor expression and collagen content, proliferation activity by Ki-67 (MIB-1), and microvessel density by CD34. Correlations were studied with Kendall tau statistics.

Results: The most powerful association was found between time to maximum enhancement and microvessel density (tau = -0.60, P < .001). Surgical bleeding (tau = 0.49, P = .002), blood loss during surgery (tau = 0.49, P = .002), progesterone receptor expression (tau = 0.59, P < .001), and collagen content (tau = -0.54, P < .001) were statistically best correlated with the relative intensity of meningioma on FLAIR images. Tissue hardness correlated best with relative intensity on T2-weighted images (tau = 0.40, P = .012).

Conclusion: Assessment of microvessel density, collagen content, and progesterone receptor expression of meningioma may be clinically feasible by using low-field MR imaging.

Fig 1.

Relative intensity on FLAIR images versus surgical bleeding of tumor tissue evaluated on VAS (τ = 0.49, P = .002).

Fig 2.

Relative intensity of tumor tissue on FLAIR images versus blood loss during surgery (τ = 0.49, P = .002).

Fig 3.

Relative intensity of tumor tissue on FLAIR images versus grade of progesterone receptor expression evaluated on a scale of 0–3 (τ = 0.59, P < .001).

Fig 4.

Relative intensity of tumor tissue on FLAIR images versus grade of collagen content evaluated on a scale of 0–3 (τ = −0.54, P < .001).

Fig 5.

Relative intensity on T2-weighted images versus hardness of tumor tissue evaluated on VAS (τ = −0.40, P = .012).

Fig 6.

Time to maximum intensity on dynamic study versus microvessel density (τ = −0.60, P < .001). m indicates meningothelial; f, fibrous; s, secretory; p, psammomatous; and a, angiomatous meningioma.

Fig 7.

Meningothelial meningioma (A) FLAIR image (relative intensity of tumor, 1.15). B, T2-weighted image (relative intensity, 1.42). Surgical bleeding, grade 4 on VAS and blood loss, 850 mL; hardness 5 on VAS; collagen content, 0; progesterone receptor expression, 1; microvessel density, 560 microvessels/mm². Time to maximum enhancement in dynamic imaging was 10 seconds from the time point when contrast agent arrived in the veins.

Fig 8.

Meningothelial meningioma (A) FLAIR image (relative intensity of tumor, 1.11). B, T2-weighted image (relative intensity, 1.05). Surgical bleeding, grade 8 on VAS and blood loss during surgery, 700 mL; hardness 4 on VAS; collagen content, 1; progesterone receptor expression, 3; microvessel density, 151 microvessels/mm². Time to maximum enhancement in dynamic imaging was 22 seconds from the time point when contrast agent arrived in the veins.

Fig 9.

Fibrous meningioma (A) FLAIR image (relative intensity of tumor, 0.72). B, T2-weighted image (relative intensity, 0.83). Surgical bleeding, grade 1.5 on VAS and blood loss, 250 mL; hardness 7.5 on VAS; collagen content, 3; progesterone receptor expression, 0; microvessel density, 81 microvessels/mm². Time to maximum enhancement in dynamic imaging was 90 seconds from the time point when contrast agent arrived in the veins.