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Determination of the AVM Nidus for Radiosurgery Using Color Intensity Projection of Cerebral Digital Subtraction Angiography
Proceedings of the 47th Annual ASTRO Meeting
and MRI resulted in alterations in target volume definition in 19 patients (73%). A differentiation between tumor and pituitary gland in lesions next to the cavernous sinus is not possible.
179
Determination of the AVM Nidus for Radiosurgery Using Color Intensity Projection of Cerebral Digital Subtraction Angiography
F. Lagerwaard,1 K.S. Cover,1 R. van den Berg,2 B.J. Slotman1 Radiation Oncology, VU University Medical Center, Amsterdam, Netherlands, 2Radiology, VU University Medical Center, Amsterdam, Netherlands
1
Purpose/Objective: Radiosurgery is an established treatment modality for cerebral arteriovenous malformations (AVM). Digital subtraction angiography (DSA), which involves the rapid generation of orthogonal X-ray images, is the standard for target definition in radiosurgery. As the AVM is filled in the arterial phase, a single anterior-posterior (AP) and lateral orthogonal image of the early DSA-phases is selected for contouring of the AVM nidus. The advantage of the temporal information stored within DSA studies over imaging techniques such as CT-angiography or MR-angiography is diminished by the lack of 3-dimensional information and overprojection of arterial or venous structures. These limitations lead to substantial inter-clinician variations in contouring AVMs. In order to better visualize AVMs on DSA, we developed and investigated the use of composite color intensity projection (CIP) images of DSA studies for target definition in radiosurgery. Materials/Methods: We developed the CIP technique, which summarizes the changes over a stack of grayscale images in a single composite color image. All areas of the images that are unchanged over the stack are presented in their original grayscale in the CIP image. Areas that have any change in pixel-intensity over the stack are indicated by color. The larger the change in intensity, the greater the saturation of the color. The time-information is added in CIPs by generating a series of minimumintensity projection images of the consecutive DSA images. The hue of the color corresponds to the time in which the intra-arterial introduced contrast arrives at a location. Early contrast-enhancement is indicated with a red hue, intermediate arrivals in green and late contrast-enhancement in blue (Figure). The color bar gives the order of all hues used. Composite CIP images were generated for both the AP and lateral series of the DSA series in 20 patients who had been treated with radiosurgery for their AVMs. In case of AVM-feeding from both the carotic and the vertebral arterial system, both series were used to derive separate CIPs. Results: The use of CIP images improved the visualization of the AVM nidus substantially, and the color stamping allows for better discrimination of the feeding arteries and draining veins. Compared to the single DSA image used to delineate the nidus in a phase when the first filling of the draining vein is visible, the composite image allows more prolonged visualization of the whole nidus in the arterial phase, in which both high flow direct AV shunts and slower flow regions within the AVM can be delineated. A comparison of target contouring on CIP images with that on routine DSA images will be presented during of the meeting. Conclusions: The generation of composite CIPs containing color-coded time-information from the entire DSA series aids in the visualization of the AVM nidus for radiosurgery.
Routine early phase image of DSA of the carotid artery in a patient with an AVM (left panel), a minimum-intensity projection of all phases of the DSA (middle panel), and the CIP image (right panel), which clearly discriminates between the arterial system and the AVM nidus (red), early draining veins (yellow and green), and the late venous draining (blue).
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Repeated Stereotactic Radiosurgery Can Result in Complete Obliteration for Large Intracranial Arteriovenous Malformations
S.K. Jabbour,1 S.M. Raza,2 Q. Thai,2 G. Pradilla,2 L.R. Kleinberg,1 M.D. Wharam,1 D. Rigamonti2 Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Hospital, Baltimore, MD, 2 Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD 1
Purpose/Objective: The treatment of large and high- grade (Spetzler-Martin III-V) arteriovenous malformations (AVMs) is a challenge, since microneurosurgery is often too risky, standard radiosurgery is often not feasible, and embolization is non-curative. Customary practice supports the use of radiosurgery as the primary modality in the treatment of AVMs of an average diameter of 3 cm or less, but there are a paucity of data to support the application of radiosurgery in larger AVMs. Here we report our institution’s experience in the treatment of large intracranial AVMs using a repeated radiosurgery technique in which low dose treatments were given at 2–3 year intervals until resolution or until the volume was small enough for safe application of standard high dose treatment. Materials/Methods: Between 1994 and 2004, 12 patients with large AVMs (median initial volume: 28.72 mL, range: 13.16 – 80.04 mL) deemed to be non-operative candidates were treated with repeated radiosurgery. Mean follow-up after the last fraction delivered was 18 months. The median age of the cohort at the time of treatment was 28 yr (mean 30.5 yr; range: 12–53 yr). Two patients had initially each received one fraction of GammaKnife stereotactic radiosurgery (GKSRS) at other
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and MRI resulted in alterations in target volume definition in 19 patients (73%). A differentiation between tumor and pituitary gland in lesions next to the cavernous sinus is not possible.
179
Determination of the AVM Nidus for Radiosurgery Using Color Intensity Projection of Cerebral Digital Subtraction Angiography
F. Lagerwaard,1 K.S. Cover,1 R. van den Berg,2 B.J. Slotman1 Radiation Oncology, VU University Medical Center, Amsterdam, Netherlands, 2Radiology, VU University Medical Center, Amsterdam, Netherlands
1
Purpose/Objective: Radiosurgery is an established treatment modality for cerebral arteriovenous malformations (AVM). Digital subtraction angiography (DSA), which involves the rapid generation of orthogonal X-ray images, is the standard for target definition in radiosurgery. As the AVM is filled in the arterial phase, a single anterior-posterior (AP) and lateral orthogonal image of the early DSA-phases is selected for contouring of the AVM nidus. The advantage of the temporal information stored within DSA studies over imaging techniques such as CT-angiography or MR-angiography is diminished by the lack of 3-dimensional information and overprojection of arterial or venous structures. These limitations lead to substantial inter-clinician variations in contouring AVMs. In order to better visualize AVMs on DSA, we developed and investigated the use of composite color intensity projection (CIP) images of DSA studies for target definition in radiosurgery. Materials/Methods: We developed the CIP technique, which summarizes the changes over a stack of grayscale images in a single composite color image. All areas of the images that are unchanged over the stack are presented in their original grayscale in the CIP image. Areas that have any change in pixel-intensity over the stack are indicated by color. The larger the change in intensity, the greater the saturation of the color. The time-information is added in CIPs by generating a series of minimumintensity projection images of the consecutive DSA images. The hue of the color corresponds to the time in which the intra-arterial introduced contrast arrives at a location. Early contrast-enhancement is indicated with a red hue, intermediate arrivals in green and late contrast-enhancement in blue (Figure). The color bar gives the order of all hues used. Composite CIP images were generated for both the AP and lateral series of the DSA series in 20 patients who had been treated with radiosurgery for their AVMs. In case of AVM-feeding from both the carotic and the vertebral arterial system, both series were used to derive separate CIPs. Results: The use of CIP images improved the visualization of the AVM nidus substantially, and the color stamping allows for better discrimination of the feeding arteries and draining veins. Compared to the single DSA image used to delineate the nidus in a phase when the first filling of the draining vein is visible, the composite image allows more prolonged visualization of the whole nidus in the arterial phase, in which both high flow direct AV shunts and slower flow regions within the AVM can be delineated. A comparison of target contouring on CIP images with that on routine DSA images will be presented during of the meeting. Conclusions: The generation of composite CIPs containing color-coded time-information from the entire DSA series aids in the visualization of the AVM nidus for radiosurgery.
Routine early phase image of DSA of the carotid artery in a patient with an AVM (left panel), a minimum-intensity projection of all phases of the DSA (middle panel), and the CIP image (right panel), which clearly discriminates between the arterial system and the AVM nidus (red), early draining veins (yellow and green), and the late venous draining (blue).
180
Repeated Stereotactic Radiosurgery Can Result in Complete Obliteration for Large Intracranial Arteriovenous Malformations
S.K. Jabbour,1 S.M. Raza,2 Q. Thai,2 G. Pradilla,2 L.R. Kleinberg,1 M.D. Wharam,1 D. Rigamonti2 Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Hospital, Baltimore, MD, 2 Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD 1
Purpose/Objective: The treatment of large and high- grade (Spetzler-Martin III-V) arteriovenous malformations (AVMs) is a challenge, since microneurosurgery is often too risky, standard radiosurgery is often not feasible, and embolization is non-curative. Customary practice supports the use of radiosurgery as the primary modality in the treatment of AVMs of an average diameter of 3 cm or less, but there are a paucity of data to support the application of radiosurgery in larger AVMs. Here we report our institution’s experience in the treatment of large intracranial AVMs using a repeated radiosurgery technique in which low dose treatments were given at 2–3 year intervals until resolution or until the volume was small enough for safe application of standard high dose treatment. Materials/Methods: Between 1994 and 2004, 12 patients with large AVMs (median initial volume: 28.72 mL, range: 13.16 – 80.04 mL) deemed to be non-operative candidates were treated with repeated radiosurgery. Mean follow-up after the last fraction delivered was 18 months. The median age of the cohort at the time of treatment was 28 yr (mean 30.5 yr; range: 12–53 yr). Two patients had initially each received one fraction of GammaKnife stereotactic radiosurgery (GKSRS) at other
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