Fig. B9.1 (A,B) MR diffusion-weighted image, axial plane. Hyperintense signals indicating acute territorial infarctions in the left PCA calcarine artery territory and left MCA prerolandic artery territories. Note the old right-sided ACA infarction (arrow) and the spared occipital pole (arrowhead). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.2 MR FLAIR image, axial plane. (A) Mild parietal atrophy on the right side. Note the dilated leptomeningeal vessels (arrowheads) indicating increased and delayed flow. (B) Besides the post-central MCA infarction, small bilateral internal BZI can be seen (arrows). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.3 Contrast-enhanced MRA showing a steno-occlusive pathology in both distal ICAs. Instead of MCA and ACA main stems, multiple bilateral small vessels can be seen, but the insular branches appear normal. Note the large diameter of the right VA, exceeding that of the right ICA. (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.4 (A) 3D TOF-MRA. Circle of Willis, coronal oblique maximal intensity projection (MIP). Absent flow signal in the M1-MCA (arrows) and A1-ACA on both sides as well as in the left PCA (arrow). Note the fine network-like collateral vessels surrounding the circle of Willis (arrowheads) (B) T2-weighted image, axial plane. In contrast to TOF-MRA, visible MCA signal voids indicate that both vessels remained open, even at its proximal site. Note that the T2-weighted images better delineate the multiple small collateral vessels surrounding the MCA, ACA, and PCA (arrowheads). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.5 DSA, right selective ICA injection, lateral view. The DSA shows a right terminal ICA occlusion (dotted arrow). Collateral flow derives in part from the PCA via the PCoA (arrowhead). Note the typical network-like anastomoses in the area of the proximal MCA, which itself is not visualized (arrows). Small dural anastomoses are also visible (arrowheads). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.6 DSA, right selective ICA injection, posteroanterior view. (A) Early arterial phase: No visible MCA but PCA leptomeningeal filling through the PCoA (arrows). Note a dural anastomosis (arrowheads). (B) Late arterial phase with visible insular and leptomeningeal branches of the right MCA and both ACA. As retrograde filling via the PCoA seemed unlikely, antegrade filling via the proximal MCA and ACA in addition to the collateral network has to be assumed, even if the M1-MCA and A1-ACA are not directly visible. (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.7 DSA, left selective VA injection, posteroanterior view. (A) Early arterial phase: Suspected stenosis of both proximal PCAs (arrowheads). Similar to the anterior circulation, a fine network can be seen surrounding both PCAs. (B) Late arterial phase: The right MCA territory is partially perfused by the PCA (arrow). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Lübeck, Germany.)

Fig. B9.8 DSA, left selective VA injection, lateral view. (A) Early arterial phase: Better delineation of the fine collateral network compared with the posteroanterior view (arrows). (B) The late arterial phase demonstrates the posterior pericallosal artery connecting via the pericallosal artery with the anterior circulation (arrowhead). (Courtesy of Prof. Schramm, Neuroradiological Department, University Hospital Schleswig-Holstein, Lübeck, Germany.)

Fig. B9.9 Extracranial duplex, longitudinal plane. The right ICA appears small showing a decreased blood volume flow (BVF 210 mL/min).

Fig. B9.10 Extracranial duplex, longitudinal plane. The right V2-VA has a large diameter and an unusually high blood volume flow (BVF 310 mL/min).

Fig. B9.11 TCCS (transtemporal approach), right-sided insonation, midbrain plane. Severely poststenotic flow pattern with a marked decreased flow in the right M1-MCA (flow velocity 21/16 cm/s). Note the color signals in the perimesencephalic cistern corresponding to the small collaterals seen in the T2-weighted MR image (arrow).

Fig. B9.12 TCCS (transtemporal approach), left-sided insonation, midbrain plane. Moderate poststenotic flow pattern with a decreased flow in the left M1-MCA (flow velocity 34/20 cm/s).