Article Figures & Data
Figures
- Fig 1.
Image evaluation and shunt approximation for a right hemisphere AVM. A, CASL perfusion ΔM maps show bright signal intensity in the sagittal sinus and right transverse sinus (arrowheads) and in draining veins (arrows) adjacent to the nidus (open arrows). B, A small region of interest (red circle) placed in the left basal ganglia is used for each patient to measure mean ΔM (BGmean) and SD (BGSD). A threshold is generated (empirically chosen as threshold = BGmean + 8 *BGSD) above which voxels are labeled as shunt voxels to create a mask (blue voxels) for the AVM and draining vessels. The AV shunt fraction is estimated by multiplying the mean ΔM in the mask by the number of voxels in the mask, then dividing by the mean ΔM in the entire brain multiplied by all labeled voxels. C, Registered 2D TOF MRA source images (no superior saturation band) are reviewed to verify reasonable selection of AVM and draining vessels (open and closed arrows).
- Fig 2.
AVM before (top) and 2 days after (bottom) partial embolization (patient 1). CASL ΔM images (A, D) show decrease in AV shunt (arrows, D), estimated decrease from 23% to 20%. Superficial venous drainage is identified, including the superior sagittal sinus and sphenobasal sinus on both studies (open arrowheads, A). Of interest, despite intense signal intensity in the sphenobasal sinus, this corresponds to a relatively small venous structure on DSA (black arrowhead, C). DSA lateral projections (C, F) and 3D TOF MRA collapsed maximum intensity projection images (B, E) confirm decreased flow in a portion of AVM, especially the posterior-superior portion (white arrowhead, E).
- Fig 3.
Susceptibility artifact resulting from the presence of embolic material, thrombus, and/or hemorrhage (patient 1). CASL source images from 4 imaging locations are shown.
- Fig 4.
Multiple postlabeling delay times (200–1500 ms): effect on ASL signal intensity in the AVM (patient 1). ΔM (T1-corrected) measured in regions of interest for the AVM (diamond), sagittal sinus (triangle), right MCA territory (box), and entire brain (circle) at each delay is plotted (above), with ΔM maps from 1 imaging location at multiple delays for comparison (below). ASL signal intensity is relatively stable in global measures over the entire brain and in the MCA at longer delays as expected. Signal intensity decreases in AVM and increases in sagittal sinus as delay increases.
- Fig 5.
Regional changes in CBF compared with extent of AV shunt. Δ = contralateral − ipsilateral CBF in measured regions of interest in white matter near the AVM, the cortex near the AVM, the thalamus, and the basal ganglia. A, Cortical gray matter CBF Δ values are negatively but weakly correlated with percent AV shunt and are not significant. (B) Δ values in white matter (R2 = 0.70, F = 11.58, P = .02) are negatively correlated (blood flow in adjacent ipsilateral white matter increases as percent shunt increased). Basal ganglia Δ values (C) show little change in CBF with the size of the AV shunt, but thalamic CBF (D) appears to decrease ipsilaterally as percent AV shunt increases (R2 = 0.74, F = 14.19, P = .01).
Tables
Patient Age (yr) Presentation Location Eloquent Tissue at Risk Grade (size/eloquent/drainage)* Arterial Supply VAT AVM/normal (s) 1 65 Headache Left frontal Broca area 2/1/0 L M2–3, L ACA 0.67/3.87 2 44 Bleed + seizures Right frontal-parietal Primary sensorimotor cortex 2/1/0 R M3–4 0.54/3.74 3 23 Hand/Face numbness Left frontal-parietal Primary sensorimotor cortex 1/1/0 L M4 0.27/3.87 4 33 Bleed + headache, expressive dysphasia Left frontal Broca area 1/1/0 L M4 NA 5 49 Headache Left occipital-temporal Visual cortex, optic radiations 1/1/0 L M4 NA 6 23 Left face/tongue spasms Right frontal-parietal Primary sensorimotor cortex 2/1/0 R M3–4 0.4/3.2 7 47 Headache, blurry vision Left frontal Broca area 2/1/1 L M1–4, L ACA 0.53/6.13 Note:—VAT indicates venous appearance time with contrast appearance in supraclinoid artery as reference point (t = 0 seconds) for both AVM and normal venous structures; NA, not available (DSA performed elsewhere); R, right; L, left; M1–4, middle cerebral artery branches; ACA, anterior cerebral artery.
* Spetzler-Martin grade by category (size, involvement of eloquent brain, and drainage pattern) with eloquent regions defined as primary sensorimotor cortex, language and visual cortex, hypothalamus and thalamus, internal capsule, brain stem, and deep cerebellar nuclei.1
Patient Grade* Shunt (%) CBF (mL/100 g/min) CBFmean BGips BGcont Thalips Thalcont GMips GMcont WMips WMcont 1 3 23.42 50.7 49.6 37.8 51.2 53.9 61.7 58.9 29.8 23.8 2 3 19.80 54.7 44.3 47 66.8 76.6 85.9 53.3 25.4 15.5 3 2 4.90 52.3 39.0 49.0 45.8 42.9 67.3 78.6 13.6 16.1 4 2 0.64 61.3 67.8 63.6 66.6 48.5 84.5 88.2 23.8 34.4 5 2 3.13 39.0 35.0 36.7 48.4 45.1 49.7 37.1 17.4 22.2 6 3 10.72 39.7 39.3 41.4 36.0 40.1 48.0 62.8 21.6 25.0 7 4 29.74 48.2 34.6 44.7 42.6 58.6 62.3 51.2 39.7 35.8 Mean 49.4 44.3 45.7 51.1 52.2 65.6 61.5 24.5 24.7 Note:—CBFmean indicates mean brain cerebral blood flow excluding AVM and associated structures; GM (WM), gray matter (white matter) blood flow averaged from regions of interest anterior and posterior to the AVM; Thal, thalamus; ips, ipsilateral; cont, contralateral.
* Grade indicates total Spetzler-Martin grade (sum of scores for size, involvement of eloquent brain, and drainage pattern as listed in Table 1).
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