Roh-Eul Yoo, Tae Jin Yun, Young Dae Cho, Jung Hyo Rhim, Koung Mi Kang, Seung Hong Choi, Ji-hoon Kim, Jeong Eun Kim, Hyun-Seung Kang, Chul-Ho Sohn, Sun-Won Park and Moon Hee Han
Arterial spin labeling perfusion-weighted imaging (ASL-PWI) enables quantification of tissue perfusion without contrast media administration. The aim of this study was to explore whether cerebral blood flow (CBF) from ASL-PWI can reliably predict angiographic vascularity of meningiomas.
Twenty-seven patients with intracranial meningiomas, who had undergone preoperative ASL-PWI and digital subtraction angiography prior to resection, were included. Angiographic vascularity was assessed using a 4-point grading scale and meningiomas were classified into 2 groups: low vascularity (Grades 0 and 1; n = 11) and high vascularity (Grades 2 and 3; n = 16). Absolute CBF, measured at the largest section of the tumor, was normalized to the contralateral gray matter. Correlation between the mean normalized CBF (nCBF) and angiographic vascularity was determined and the mean nCBF values of the 2 groups were compared. Diagnostic performance of the nCBF for differentiating between the 2 groups was assessed.
The nCBF had a significant positive correlation with angiographic vascularity (ρ = 0.718; p < 0.001). The high-vascularity group had a significantly higher nCBF than the low-vascularity group (3.334 ± 2.768 and 0.909 ± 0.468, respectively; p = 0.003). At the optimal nCBF cutoff value of 1.733, sensitivity and specificity for the differential diagnosis of the 2 groups were 69% (95% CI 41%–89%) and 100% (95% CI 72%–100%), respectively. The area under the receiver operating characteristic curve was 0.875 (p < 0.001).
ASL-PWI may provide a reliable and noninvasive means of predicting angiographic vascularity of meningiomas. It may thus assist in selecting potential candidates for preoperative digital subtraction angiography and embolization in clinical practice.
Yun-Sik Dho, Young Jae Kim, Kwang Gi Kim, Sung Hwan Hwang, Kyung Hyun Kim, Jin Wook Kim, Yong Hwy Kim, Seung Hong Choi and Chul-Kee Park
The aim of this study was to analyze the positional effect of MRI on the accuracy of neuronavigational localization for posterior fossa (PF) lesions when the operation is performed with the patient in the prone position.
Ten patients with PF tumors requiring surgery in the prone position were prospectively enrolled in the study. All patients underwent preoperative navigational MRI in both the supine and prone positions in a single session. Using simultaneous intraoperative registration of the supine and prone navigational MR images, the authors investigated the images’ accuracy, spatial deformity, and source of errors for PF lesions. Accuracy was determined in terms of differences in the ability of the supine and prone MR images to localize 64 test points in the PF by using a neuronavigation system. Spatial deformities were analyzed and visualized by in-house–developed software with a 3D reconstruction function and spatial calculation of the MRI data. To identify the source of differences, the authors investigated the accuracy of fiducial point localization in the supine and prone MR images after taking the surface anatomy and age factors into consideration.
Neuronavigational localization performed using prone MRI was more accurate for PF lesions than routine supine MRI prior to prone position surgery. Prone MRI more accurately localized 93.8% of the tested PF areas than supine MRI. The spatial deformities in the neuronavigation system calculated using the supine MRI tended to move in the posterior-superior direction from the actual anatomical landmarks. The average distance of the spatial differences between the prone and supine MR images was 6.3 mm. The spatial difference had a tendency to increase close to the midline. An older age (> 60 years) and fiducial markers adjacent to the cervical muscles were considered to contribute significantly to the source of differences in the positional effect of neuronavigation (p < 0.001 and p = 0.01, respectively).
This study demonstrated the superior accuracy of neuronavigational localization with prone-position MRI during prone-position surgery for PF lesions. The authors recommend that the scan position of the neuronavigational MRI be matched with the surgical position for more precise localization.