Toward Normal Perfusion after Radiosurgery: Perfusion MR Imaging with Independent Component Analysis of Brain Arteriovenous Malformations
Wan-Yuo Guoa,e,
Yu-Te Wub,f,
Hsiu-Mei Wua,e,
Wen-Yuh Chungc,e,
Yi-Hsuan Kaof,
Tzu-Chen Yeha,b,e,
Cheng-Ying Shiaud,e,
D. Hung-Chi Panc,e,
Yue-Cune Changh and
Jen-Chuen Hsiehb,e,g
a Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
b Departments of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
c Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
d Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
e Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC
f Institute of Radiological Science, National Yang-Ming University, Taipei, Taiwan, ROC
g Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan, ROC
h Department of Mathematics, Tamkang University, Taipei, Taiwan, ROC
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FIG 1. Schematic shows the ROIs for perfusion measurement on the target section of a DSC-MR image. N indicates AVM nidus; H, the rest of the ipsilateral hemisphere; P, posterior immediate; Pr, posterior remote; A, anterior immediate; Ar, anterior remote. Similar ROIs of the contralateral hemisphere (N1, H1, P1, Pr1, A1, and Ar1) were used as controls.
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FIG 2. Schematic shows three types of perfusion disturbance: type 1, high perfusion in both immediate and remote perinidal areas; type 2, high perfusion in immediate and low perfusion in perinidal remote areas; and type 3, low perfusion in both immediate and remote perinidal areas. N indicates AVM nidus.
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FIG 4. MR images in case 16.
Upper row (before radiosurgery), Lateral right carotid digital subtraction angiogram shows a parietal AVM with arteriovenous shunts and early venous drainage (black arrow); collapsed-view 3D time-of-flight MR angiogram and T1- and T2-wighted transaxial MR images show the AVM (yellow arrows).
Lower row (13 months after radiosurgery), MR images show the partially regressed AVM nidus and mild radiation-induced edema (red arrow).
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FIG 5. Perfusion maps in case 16.
Upper row (before radiosurgery), Perfusion maps show decrease in rCBV and rCBF in the immediate anterior and anterior remote areas and prolonged rMTT (red arrows), indicating type 3 perfusion disturbance.
Lower row (13 months after radiosurgery), Perfusion maps show improvement of perfusion toward normal, particularly in the anterior remote region (yellow arrow).
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FIG 6. Composite images in case 3.
Upper row (before radiosurgery), Collapsed-view 3D time-of-flight MR angiogram shows a left temporal lobe AVM (white arrow). T2-weighted transaxial image shows the AVM. Perfusion maps show increased rCBV and rCBF in the immediate anterior and posterior areas (red arrows), and decreased rCBV and rCBF in the posterior remote area (yellow arrow), indicating type 2 perfusion disturbance.
Lower row (24 months after radiosurgery), Collapsed-view 3D time-of-flight MR angiogram shows a small remnant of the AVM. T2-weighted transaxial image shows a moderate degree of radiation-induced edema. Perfusion maps show decreased rCBV and rCBF in the perinidal regions (arrowheads). They correspond to the regions with radiation-induced edema.
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FIG 7. Plot shows composite AVM nidus volumes in the 19 patients before and every 6 months after radiosurgery. The volumes gradually regress after radiosurgery. Vertical axis indicates volume in mL defined on 3D time-of-flight MR angiograms (data are the mean and 1 SD).
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FIG 8. Plot shows composite N/N1 parameter ratios (data are the mean and 1 SD) in the 19 patients with AVM before and every 6 months after radiosurgery. N/N1 rCBV and rCBF ratios significantly decrease (both P < .001) and N/N1 rMTT ratios significantly increase (P < .015) after radiosurgery (generalized linear models with the generalized estimating equations method).
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FIG 9. Plot shows composite A/A1, P/P1 and H/H1 parameter ratios in the 19 patients with AVM before and every 6 months after radiosugery. Postradiosurgical A/A1, H/H1 and P/P1 rCBV and rCBF ratios are significantly deviated from baseline values (all P < .005, generalized linear models with the generalized estimating equations method).
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FIG 10. Composite images in case 2.
Upper images (before radiosurgery), Collapsed-view 3D time-of-flight MR angiogram shows a left frontoparietal AVM (white arrow). A five-independent-component image shows the arteries component (AVM) and the other components. rCBV and rCBF maps show the abnormal transnidal flow and three steal types (1, 2, 3) in the same patient.
Lower images (24 months after radiosurgery), T2-weighted transaxial image shows no evidence of a remaining nidus; severe radiation-induced edema (yellow arrow) is present. The five-independent-component image shows regression of the arteries component. On rCBV and rCBF maps, no abnormal transnidal flow is seen. The perinidal regions show a decrease in rCBV and rCBF. The perfusion impairments are secondary to radiation-induced edema (red arrows).
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), rCBF (), rMTT (
) ratios between the composite data of five healthy subjects and 19 patients with AVM (data are the mean and 95% confidence interval). The H/H1 rCBV and rCBF ratios of the patients are significantly higher than those of the healthy subjects (P < .001 and P = .001, respectively). This indicates that the hemisphere with the lesion has higher flow and volume. For the H/H1 rMTT ratio, P = .270 (nonparametric Mann-Whitney U tests).