MR angiography fusion technique for treatment planning of intracranial arteriovenous malformations
ABSTRACT To develop an image fusion technique using elliptical centric contrast-enhanced (CE) MR angiography (MRA) and three-dimensional (3D) time-of-flight (TOF) acquisitions for radiosurgery treatment planning of arteriovenous malformations (AVMs).
CE and 3D-TOF MR angiograms with disparate in-plane fields of view (FOVs) were acquired, followed by k-space reformatting to provide equal voxel dimensions. Spatial domain addition was performed to provide a third, fused data volume. Spatial distortion was evaluated on an MRA phantom and provided slice-dependent and global distortion along the three physical dimensions of the MR scanner. In vivo validation was performed on 10 patients with intracranial AVMs prior to their conventional angiogram on the day of gamma knife radiosurgery.
Spatial distortion in the phantom within a volume of 14 x 14 x 3.2 cm(3) was less than +/-1 mm (+/-1 standard deviation (SD)) for CE and 3D-TOF data sets. Fused data volumes were successfully generated for all 10 patients.
Image fusion can be used to obtain high-resolution CE-MRA images of intracranial AVMs while keeping the fiducial markers needed for gamma knife radiosurgery planning. The spatial fidelity of these data is within the tolerance acceptable for daily quality control (QC) purposes and gamma knife treatment planning.
SourceAvailable from: Hiroshi K Inoue[Show abstract] [Hide abstract]
ABSTRACT: Precise target detection is essential for radiosurgery, neurosurgery and hypofractionated radiotherapy because treatment results and complication rates are related to accuracy of the target definition.03/2015; 7(3):e252. DOI:10.7759/cureus.252
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ABSTRACT: Neuroimaging is the gold standard for diagnosis and follow-up of brain arteriovenous malformations (bAVMs), but no objective parameter has been validated for the assessment of the nidus angioarchitecture and for prognostication following treatment. The fractal dimension (FD), which is a mathematical parameter able to quantify the space-filling properties and roughness of natural objects, may be useful in quantifying the geometrical complexity of bAVMs nidus. To propose FD as a neuroimaging biomarker of the nidus angioarchitecture, which might be related to radiosurgical outcome. We retrospectively analyzed 54 patients who had undergone stereotactic radiosurgery for the treatment of bAVMs. The quantification of the geometric complexity of the vessels forming the nidus, imaged in MRI, was assessed by means of the box-counting method to obtain the fractal dimension. FD was found to be significantly associated with the size (p=0.026) and volume (p<0.001) of the nidus, in addition to several angioarchitectural parameters. A non-significant association between clinical outcome and FD was observed [AUC 0.637 [95% confidence interval, 0.49, 0.79], indicative of a potential inverse relationship between FD and bAVM obliteration. In our exploratory methodological research, we showed that the FD is an objective computer-aided parameter for quantifying the geometrical complexity and roughness of the bAVM nidus. The results suggest that more complex bAVM angioarchitecture, having higher FD values, might be related to decreased response to radiosurgery and that the FD of the bAVM nidus could be used as a morphometric neuroimaging biomarker.Neurosurgery 03/2014; 75(1). DOI:10.1227/NEU.0000000000000353 · 3.03 Impact Factor
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ABSTRACT: The preoperative evaluation of patients with intracranial aneurysms typically includes a contrast-enhanced vascular study, such as computed tomography angiography (CTA), magnetic resonance angiography (MRA), or digital subtraction angiography. However, there are numerous absolute and relative contraindications to the administration of imaging contrast agents, including pregnancy, severe contrast allergy, and renal insufficiency. Evaluation of patients with contrast contraindications thus presents a unique challenge. We identified three patients with absolute contrast contraindications who presented with intracranial aneurysms. One patient was pregnant, while the other two had previous severe anaphylactic reactions to iodinated contrast. Because of these contraindications to intravenous contrast, we performed non-contrast time-of-flight MRA with 3D reconstruction (TOF MRA with 3DR) with maximum intensity projections and volume renderings as part of the preoperative evaluation prior to successful open surgical clipping of the aneurysms. In the case of one paraclinoid aneurysm, a high-resolution non-contrast CT scan was also performed to assess the relationship of the aneurysm to the anterior clinoid process. TOF MRA with 3DR successfully identified the intracranial aneurysms and adequately depicted the surrounding microanatomy. Intraoperative findings were as predicted by the preoperative imaging studies. The aneurysms were successfully clip-obliterated, and the patients had uneventful post-operative courses. These cases demonstrate that non-contrast imaging is a viable modality to assess intracranial aneurysms as part of the surgical planning process in patients with contrast contraindications. TOF MRA with 3DR, in conjunction with high-resolution non-contrast CT when indicated, provides adequate visualization of the microanatomy of the aneurysm and surrounding structures.Journal of Clinical Neuroscience 05/2013; 20(8). DOI:10.1016/j.jocn.2012.12.005 · 1.32 Impact Factor