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Comprehensive Imaging of Ischemic Stroke with Multisection CT¹

¹ From the Division of Neuroradiology, Department of Neurosurgery (B.F.T., W.J.H., K.E.E.) and the Departments of Neurology (R.H., B.S., F.R.) and Internal Medicine II (S.F.M.), University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; and Siemens Medical Solutions, Forchheim, Germany (E.K.). Recipient of a Magna Cum Laude award for an education exhibit at the 2001 RSNA scientific assembly. Received February 26, 2002; revision requested April 24; final revision received November 14; accepted November 15. Address correspondence to B.F.T. (e-mail: tomandl@neuroradiologie-erlangen.de).

View larger version (45K): [in a new window]   Figure 1.  Chart illustrates a protocol for evaluating stroke patients with multisection CT and the average time needed to complete each step. Note that perfusion CT data are being evaluated while CT angiograms are being acquired and reformatted. CBF = cerebral blood flow, CBV = cerebral blood volume, MIP = maximum intensity projection, MPR = multiplanar reformatting, TTP = time to peak.

View larger version (31K): [in a new window]   Figure 2.  Graph illustrates a TAC plotted from perfusion CT data obtained in normal brain tissue. From this curve, per-voxel hemodynamic variables are calculated for TTP, CBF, and CBV. TTP is the time from the start of injection until maximum contrast enhancement is reached. However, some authors prefer to measure TTP from the beginning of enhancement by subtracting "time to start" (ie, the time between the start of injection and the start of enhancement). CBF can be estimated from the "maximum slope" of the curve. CBV is calculated from the area under the normalized curve and can also be estimated from the maximum enhancement compared with that of a reference vessel (eg, intracranial artery, superior sagittal sinus).

View larger version (96K): [in a new window]   Figure 3a.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (107K): [in a new window]   Figure 3b.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (114K): [in a new window]   Figure 3c.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (116K): [in a new window]   Figure 3d.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (121K): [in a new window]   Figure 3e.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (24K): [in a new window]   Figure 3f.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (93K): [in a new window]   Figure 3g.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (137K): [in a new window]   Figure 3h.  Evaluation of perfusion CT data. (a) Nonenhanced CT scan obtained 5 hours after the onset of stroke in a 65-year-old woman with MCA occlusion demonstrates obscuration of the lentiform nucleus (long white arrow) and of the head of the caudate nucleus (arrowhead) as well as hypoattenuation of the insular ribbon (short white arrow) and effacement of the sulci of the temporoparietal MCA territory (black arrows). (b-d) Color maps of TTP (b), CBF (c), and CBV (d) demonstrate a ribbon-shaped area of nonperfusion (small white arrows) and markedly reduced perfusion in the residual MCA territory. The reduction of CBF and CBV appears to be more severe in the temporoparietal MCA territory (arrowhead) than in the frontal territory (large arrow). (e, f) Image and graphs illustrate TACs obtained within the superior sagittal sinus (1), normal brain parenchyma (2), the anterior part of the MCA territory (3), the temporoparietal MCA territory (4), and a nonperfused area (5) and compared with a TAC obtained within a branch of the MCA. Enhancement starts approximately 5 seconds later in the superior sagittal sinus than in the MCA. Although the maximum slopes of the TACs are nearly identical, maximum enhancement is much higher within the large superior sagittal sinus due to less partial volume effects. The reduction of the maximum slope in the anterior part of the MCA territory compared with the superior sagittal sinus and the normal brain parenchyma is compatible with moderately reduced blood flow. There is further reduction of the maximum slope and decreased maximum enhancement in the temporoparietal MCA territory compared with the normal brain parenchyma. At follow-up, this area was infarcted. The TAC for the nonperfused area shows no enhancement, a finding that indicates irreversible infarction. (g) Image shows two ROIs, one within the frontal (1a) and the other within the temporoparietal (2a) portion of the MCA territory, defined for comparison with the corresponding areas on the opposite side (1b, 2b). The automatically calculated relative values for CBF and CBV within the ROIs are shown in the table beneath the image. A = area of the ROI (in square centimeters), R = relative value compared with the corresponding area on the opposite side. Comparison of ROI 1a with the opposite side shows relative values of 61% and 77% for CBF and CBV, respectively. These values indicate oligemic tissue that is near the threshold for tissue at risk. The CBF and CBV values in area 2a are markedly to severely reduced, indicating brain tissue that will probably not survive. (h) Nonenhanced CT scan obtained 3 months after the onset of stroke demonstrates infarction of the left basal ganglia and temporoparietal MCA territory (arrows).

View larger version (59K): [in a new window]   Figure 4a.  MIP imaging of the circle of Willis. A ROI is defined with use of a bounding box (arrows in a). Because the MIP algorithm demonstrates only the brightest voxels in a given volume, the skull base has been excluded. The resulting MIP image (superior view) is shown in b.

View larger version (138K): [in a new window]   Figure 4b.  MIP imaging of the circle of Willis. A ROI is defined with use of a bounding box (arrows in a). Because the MIP algorithm demonstrates only the brightest voxels in a given volume, the skull base has been excluded. The resulting MIP image (superior view) is shown in b.

View larger version (125K): [in a new window]   Figure 5a.  Three-dimensional imaging of the vertebral and basilar arteries from CT angiographic data. (a) On a sagittal multiplanar reformatted image obtained in the midline, a coronal plane is defined parallel to the clivus (diagonal yellow line). Horizontal yellow line indicates axial plane. (b) Anterior thin-section (10-mm) MIP image obtained in the coronal plane defined in a demonstrates the course of the distal vertebral arteries and the basilar artery. Note that in the area of calcification (arrows) it is impossible to see the lumen of the vessel. The right vertebral artery is hypoplastic (arrowhead). (c) Three-dimensional shaded surface display (SSD) image (upper posterior view) is not helpful in this case because it integrates the calcifications and the vessel wall, thereby giving the erroneous impression of enlarged rather than calcified arteries (arrows). (d) Three-dimensional volume-rendered (VR) image depicts the intracranial arteries and the calcifications within the vertebral and basilar arteries (arrows).

View larger version (84K): [in a new window]   Figure 5b.  Three-dimensional imaging of the vertebral and basilar arteries from CT angiographic data. (a) On a sagittal multiplanar reformatted image obtained in the midline, a coronal plane is defined parallel to the clivus (diagonal yellow line). Horizontal yellow line indicates axial plane. (b) Anterior thin-section (10-mm) MIP image obtained in the coronal plane defined in a demonstrates the course of the distal vertebral arteries and the basilar artery. Note that in the area of calcification (arrows) it is impossible to see the lumen of the vessel. The right vertebral artery is hypoplastic (arrowhead). (c) Three-dimensional shaded surface display (SSD) image (upper posterior view) is not helpful in this case because it integrates the calcifications and the vessel wall, thereby giving the erroneous impression of enlarged rather than calcified arteries (arrows). (d) Three-dimensional volume-rendered (VR) image depicts the intracranial arteries and the calcifications within the vertebral and basilar arteries (arrows).

View larger version (172K): [in a new window]   Figure 5c.  Three-dimensional imaging of the vertebral and basilar arteries from CT angiographic data. (a) On a sagittal multiplanar reformatted image obtained in the midline, a coronal plane is defined parallel to the clivus (diagonal yellow line). Horizontal yellow line indicates axial plane. (b) Anterior thin-section (10-mm) MIP image obtained in the coronal plane defined in a demonstrates the course of the distal vertebral arteries and the basilar artery. Note that in the area of calcification (arrows) it is impossible to see the lumen of the vessel. The right vertebral artery is hypoplastic (arrowhead). (c) Three-dimensional shaded surface display (SSD) image (upper posterior view) is not helpful in this case because it integrates the calcifications and the vessel wall, thereby giving the erroneous impression of enlarged rather than calcified arteries (arrows). (d) Three-dimensional volume-rendered (VR) image depicts the intracranial arteries and the calcifications within the vertebral and basilar arteries (arrows).

View larger version (139K): [in a new window]   Figure 5d.  Three-dimensional imaging of the vertebral and basilar arteries from CT angiographic data. (a) On a sagittal multiplanar reformatted image obtained in the midline, a coronal plane is defined parallel to the clivus (diagonal yellow line). Horizontal yellow line indicates axial plane. (b) Anterior thin-section (10-mm) MIP image obtained in the coronal plane defined in a demonstrates the course of the distal vertebral arteries and the basilar artery. Note that in the area of calcification (arrows) it is impossible to see the lumen of the vessel. The right vertebral artery is hypoplastic (arrowhead). (c) Three-dimensional shaded surface display (SSD) image (upper posterior view) is not helpful in this case because it integrates the calcifications and the vessel wall, thereby giving the erroneous impression of enlarged rather than calcified arteries (arrows). (d) Three-dimensional volume-rendered (VR) image depicts the intracranial arteries and the calcifications within the vertebral and basilar arteries (arrows).

View larger version (152K): [in a new window]   Figure 6a.  Fast analysis of the carotid bifurcation from CT angiographic data. (a) On an axial CT scan obtained a short distance above the bifurcation, a plane (arrows) is defined that will allow visualization of the right ICA. (b) Sagittal multiplanar reformatted image (right lateral view) obtained in the plane defined in a shows parts of the ICA from the bifurcation to the skull base (arrows). (c) Thin-section (15-mm) MIP image (right lateral view) obtained in the plane defined in a allows visualization of the entire length of the normal right ICA. Note the moderate artifacts due to dental inlays (arrows).

View larger version (128K): [in a new window]   Figure 6b.  Fast analysis of the carotid bifurcation from CT angiographic data. (a) On an axial CT scan obtained a short distance above the bifurcation, a plane (arrows) is defined that will allow visualization of the right ICA. (b) Sagittal multiplanar reformatted image (right lateral view) obtained in the plane defined in a shows parts of the ICA from the bifurcation to the skull base (arrows). (c) Thin-section (15-mm) MIP image (right lateral view) obtained in the plane defined in a allows visualization of the entire length of the normal right ICA. Note the moderate artifacts due to dental inlays (arrows).

View larger version (121K): [in a new window]   Figure 6c.  Fast analysis of the carotid bifurcation from CT angiographic data. (a) On an axial CT scan obtained a short distance above the bifurcation, a plane (arrows) is defined that will allow visualization of the right ICA. (b) Sagittal multiplanar reformatted image (right lateral view) obtained in the plane defined in a shows parts of the ICA from the bifurcation to the skull base (arrows). (c) Thin-section (15-mm) MIP image (right lateral view) obtained in the plane defined in a allows visualization of the entire length of the normal right ICA. Note the moderate artifacts due to dental inlays (arrows).

View larger version (96K): [in a new window]   Figure 7a.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (113K): [in a new window]   Figure 7b.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (60K): [in a new window]   Figure 7c.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (76K): [in a new window]   Figure 7d.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (98K): [in a new window]   Figure 7e.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (67K): [in a new window]   Figure 7f.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (72K): [in a new window]   Figure 7g.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (80K): [in a new window]   Figure 7h.  Evaluation of the right carotid bifurcation from CT angiographic data with use of right lateral 3D images. (a) Digital subtraction angiogram clearly demonstrates the extent of a primary calcified stenosis (arrow). A second minor calcified stenosis is also seen (arrowhead). (b) Axial CT scan shows severe stenosis of the right ICA. The blood-filled lumen within the stenosis is visible as a small white spot (arrow). A surrounding soft plaque (top arrowhead) and calcifications (bottom arrowhead) are also seen. (c) On an SSD image, the stenosis is not visible because the calcifications cannot be differentiated from the lumen of the artery. (d) MIP image shows the calcified stenosis (arrow), but the degree of stenosis is difficult to determine. In addition, it is hard to say whether the inferior calcification (arrowhead) narrows the lumen of the carotid artery. (e) Curved multiplanar reformatted image obtained in the area of the stenosis allows better estimation of the degree of stenosis than does the MIP image (inset). Double-headed arrow indicates corresponding anatomic structures on the two images. (f) High-opacity VR image shows the carotid bifurcation and allows visualization of both the superior (arrow) and inferior (arrowhead) calcifications. (g, h) Lower-opacity VR images allow estimation of the degree of stenosis (arrow). The inferior calcification (arrowhead) is better visualized with a more superior view (h), which demonstrates that the circumferential plaque (cf b) does not cause significant stenosis.

View larger version (123K): [in a new window]   Figure 8a.  (a-c) Nonenhanced CT scan (a), perfusion CT scan (b), and SSD image from CT angiography (c) obtained 2 hours after the onset of symptoms in a 65-year-old woman with left hemiplegia demonstrate normal findings. (d) Diffusion-weighted MR image (b = 1,000 s/mm2) shows a small ischemic lesion in the right posterior internal capsule (arrow).

View larger version (111K): [in a new window]   Figure 8b.  (a-c) Nonenhanced CT scan (a), perfusion CT scan (b), and SSD image from CT angiography (c) obtained 2 hours after the onset of symptoms in a 65-year-old woman with left hemiplegia demonstrate normal findings. (d) Diffusion-weighted MR image (b = 1,000 s/mm2) shows a small ischemic lesion in the right posterior internal capsule (arrow).

View larger version (184K): [in a new window]   Figure 8c.  (a-c) Nonenhanced CT scan (a), perfusion CT scan (b), and SSD image from CT angiography (c) obtained 2 hours after the onset of symptoms in a 65-year-old woman with left hemiplegia demonstrate normal findings. (d) Diffusion-weighted MR image (b = 1,000 s/mm2) shows a small ischemic lesion in the right posterior internal capsule (arrow).

View larger version (133K): [in a new window]   Figure 8d.  (a-c) Nonenhanced CT scan (a), perfusion CT scan (b), and SSD image from CT angiography (c) obtained 2 hours after the onset of symptoms in a 65-year-old woman with left hemiplegia demonstrate normal findings. (d) Diffusion-weighted MR image (b = 1,000 s/mm2) shows a small ischemic lesion in the right posterior internal capsule (arrow).

View larger version (46K): [in a new window]   Figure 9a.  (a) Nonenhanced CT scans obtained 5 hours after the onset of symptoms in a 60-year-old man with motoric aphasia and slight right hemiparesis demonstrate normal findings. (b) Perfusion CT study shows a small, wedge-shaped area of nonperfused brain in the left frontal lobe that is best seen on the lower images (arrow). In addition, there is a 3-second prolongation of TTP (measurement not shown) within the entire left hemisphere (green area on TTP maps). (c) MIP images from CT angiography show a high-grade stenosis of the left ICA (straight arrow) that results in narrowing of the distal lumen of the ICA (arrowheads) and of the MCA (curved arrow). The right carotid artery and the basilar artery are normal. (d) Nonenhanced CT scans obtained 3 weeks after the onset of stroke demonstrate infarction of the frontal portion of the lentiform nucleus (arrow) and a small infarction in the left frontal lobe (arrowhead).

View larger version (93K): [in a new window]   Figure 9b.  (a) Nonenhanced CT scans obtained 5 hours after the onset of symptoms in a 60-year-old man with motoric aphasia and slight right hemiparesis demonstrate normal findings. (b) Perfusion CT study shows a small, wedge-shaped area of nonperfused brain in the left frontal lobe that is best seen on the lower images (arrow). In addition, there is a 3-second prolongation of TTP (measurement not shown) within the entire left hemisphere (green area on TTP maps). (c) MIP images from CT angiography show a high-grade stenosis of the left ICA (straight arrow) that results in narrowing of the distal lumen of the ICA (arrowheads) and of the MCA (curved arrow). The right carotid artery and the basilar artery are normal. (d) Nonenhanced CT scans obtained 3 weeks after the onset of stroke demonstrate infarction of the frontal portion of the lentiform nucleus (arrow) and a small infarction in the left frontal lobe (arrowhead).

View larger version (64K): [in a new window]   Figure 9c.  (a) Nonenhanced CT scans obtained 5 hours after the onset of symptoms in a 60-year-old man with motoric aphasia and slight right hemiparesis demonstrate normal findings. (b) Perfusion CT study shows a small, wedge-shaped area of nonperfused brain in the left frontal lobe that is best seen on the lower images (arrow). In addition, there is a 3-second prolongation of TTP (measurement not shown) within the entire left hemisphere (green area on TTP maps). (c) MIP images from CT angiography show a high-grade stenosis of the left ICA (straight arrow) that results in narrowing of the distal lumen of the ICA (arrowheads) and of the MCA (curved arrow). The right carotid artery and the basilar artery are normal. (d) Nonenhanced CT scans obtained 3 weeks after the onset of stroke demonstrate infarction of the frontal portion of the lentiform nucleus (arrow) and a small infarction in the left frontal lobe (arrowhead).

View larger version (53K): [in a new window]   Figure 9d.  (a) Nonenhanced CT scans obtained 5 hours after the onset of symptoms in a 60-year-old man with motoric aphasia and slight right hemiparesis demonstrate normal findings. (b) Perfusion CT study shows a small, wedge-shaped area of nonperfused brain in the left frontal lobe that is best seen on the lower images (arrow). In addition, there is a 3-second prolongation of TTP (measurement not shown) within the entire left hemisphere (green area on TTP maps). (c) MIP images from CT angiography show a high-grade stenosis of the left ICA (straight arrow) that results in narrowing of the distal lumen of the ICA (arrowheads) and of the MCA (curved arrow). The right carotid artery and the basilar artery are normal. (d) Nonenhanced CT scans obtained 3 weeks after the onset of stroke demonstrate infarction of the frontal portion of the lentiform nucleus (arrow) and a small infarction in the left frontal lobe (arrowhead).

View larger version (49K): [in a new window]   Figure 10a.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (95K): [in a new window]   Figure 10b.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (74K): [in a new window]   Figure 10c.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (88K): [in a new window]   Figure 10d.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (127K): [in a new window]   Figure 10e.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (181K): [in a new window]   Figure 10f.  (a) Nonenhanced CT scans obtained 35 minutes after the onset of symptoms in a 76-year-old woman with complete aphasia and right hemiplegia demonstrate an old ischemic lesion in the left frontal lobe (arrow) but no early signs of infarction. (b) Perfusion CT study demonstrates a large region of markedly reduced perfusion (red area on the TTP maps, blue area on the CBF and CBV maps). Comparison with the opposite hemisphere yielded relative values of 43% and 63% for CBF and CBV, respectively, findings that indicate tissue at risk. The patient’s symptoms resolved spontaneously 30 minutes after the CT examination. (c) MIP images (superior view) from CT angiography show occlusion of the left MCA (arrow). The carotid arteries and the basilar artery are normal. (d) Nonenhanced CT scans obtained 24 hours after the onset of stroke do not show any changes from the initial examination (cf a). (e) Follow-up perfusion CT scan shows a normal color map of TTP with symmetric perfusion. (f) CT angiogram demonstrates spontaneous recanalization of the MCA.

View larger version (52K): [in a new window]   Figure 11a.  (a) Nonenhanced CT scans obtained 2 hours after the onset of symptoms in a 73-year-old man with right hemiplegia and complete aphasia demonstrate partial obscuration of the lentiform nucleus and subtle swelling and hypoattenuation of the left temporal lobe (arrows), findings that indicate infarction. (b) Perfusion CT study demonstrates relative values of 60% and 72% for CBF and CBV, respectively within the MCA territory, findings that indicate tissue at risk. In addition, a small area of nonperfusion is seen within the lentiform nucleus (arrow). (c) MIP images (superior view) from CT angiography show distal occlusion of the left MCA (arrow). The carotid arteries and basilar artery are normal except for calcification of the left carotid bifurcation (far left). (d) Nonenhanced CT scans obtained 2 hours after the onset of systemic intravenous thrombolysis show the beginning of hemorrhagic transformation of the lentiform nucleus (arrow) and increasing hypoattenuation within the temporal lobe. Follow-up CT angiography demonstrated patency of the MCA, a finding that indicated successful thrombolysis. (e) CT scans obtained 2 days later show that the hemorrhage has increased in size (arrow). There is no infarction in the cortex of the MCA territory except in the temporal lobe.

View larger version (121K): [in a new window]   Figure 11b.  (a) Nonenhanced CT scans obtained 2 hours after the onset of symptoms in a 73-year-old man with right hemiplegia and complete aphasia demonstrate partial obscuration of the lentiform nucleus and subtle swelling and hypoattenuation of the left temporal lobe (arrows), findings that indicate infarction. (b) Perfusion CT study demonstrates relative values of 60% and 72% for CBF and CBV, respectively within the MCA territory, findings that indicate tissue at risk. In addition, a small area of nonperfusion is seen within the lentiform nucleus (arrow). (c) MIP images (superior view) from CT angiography show distal occlusion of the left MCA (arrow). The carotid arteries and basilar artery are normal except for calcification of the left carotid bifurcation (far left). (d) Nonenhanced CT scans obtained 2 hours after the onset of systemic intravenous thrombolysis show the beginning of hemorrhagic transformation of the lentiform nucleus (arrow) and increasing hypoattenuation within the temporal lobe. Follow-up CT angiography demonstrated patency of the MCA, a finding that indicated successful thrombolysis. (e) CT scans obtained 2 days later show that the hemorrhage has increased in size (arrow). There is no infarction in the cortex of the MCA territory except in the temporal lobe.

View larger version (58K): [in a new window]   Figure 11c.  (a) Nonenhanced CT scans obtained 2 hours after the onset of symptoms in a 73-year-old man with right hemiplegia and complete aphasia demonstrate partial obscuration of the lentiform nucleus and subtle swelling and hypoattenuation of the left temporal lobe (arrows), findings that indicate infarction. (b) Perfusion CT study demonstrates relative values of 60% and 72% for CBF and CBV, respectively within the MCA territory, findings that indicate tissue at risk. In addition, a small area of nonperfusion is seen within the lentiform nucleus (arrow). (c) MIP images (superior view) from CT angiography show distal occlusion of the left MCA (arrow). The carotid arteries and basilar artery are normal except for calcification of the left carotid bifurcation (far left). (d) Nonenhanced CT scans obtained 2 hours after the onset of systemic intravenous thrombolysis show the beginning of hemorrhagic transformation of the lentiform nucleus (arrow) and increasing hypoattenuation within the temporal lobe. Follow-up CT angiography demonstrated patency of the MCA, a finding that indicated successful thrombolysis. (e) CT scans obtained 2 days later show that the hemorrhage has increased in size (arrow). There is no infarction in the cortex of the MCA territory except in the temporal lobe.

View larger version (52K): [in a new window]   Figure 11d.  (a) Nonenhanced CT scans obtained 2 hours after the onset of symptoms in a 73-year-old man with right hemiplegia and complete aphasia demonstrate partial obscuration of the lentiform nucleus and subtle swelling and hypoattenuation of the left temporal lobe (arrows), findings that indicate infarction. (b) Perfusion CT study demonstrates relative values of 60% and 72% for CBF and CBV, respectively within the MCA territory, findings that indicate tissue at risk. In addition, a small area of nonperfusion is seen within the lentiform nucleus (arrow). (c) MIP images (superior view) from CT angiography show distal occlusion of the left MCA (arrow). The carotid arteries and basilar artery are normal except for calcification of the left carotid bifurcation (far left). (d) Nonenhanced CT scans obtained 2 hours after the onset of systemic intravenous thrombolysis show the beginning of hemorrhagic transformation of the lentiform nucleus (arrow) and increasing hypoattenuation within the temporal lobe. Follow-up CT angiography demonstrated patency of the MCA, a finding that indicated successful thrombolysis. (e) CT scans obtained 2 days later show that the hemorrhage has increased in size (arrow). There is no infarction in the cortex of the MCA territory except in the temporal lobe.

View larger version (52K): [in a new window]   Figure 11e.  (a) Nonenhanced CT scans obtained 2 hours after the onset of symptoms in a 73-year-old man with right hemiplegia and complete aphasia demonstrate partial obscuration of the lentiform nucleus and subtle swelling and hypoattenuation of the left temporal lobe (arrows), findings that indicate infarction. (b) Perfusion CT study demonstrates relative values of 60% and 72% for CBF and CBV, respectively within the MCA territory, findings that indicate tissue at risk. In addition, a small area of nonperfusion is seen within the lentiform nucleus (arrow). (c) MIP images (superior view) from CT angiography show distal occlusion of the left MCA (arrow). The carotid arteries and basilar artery are normal except for calcification of the left carotid bifurcation (far left). (d) Nonenhanced CT scans obtained 2 hours after the onset of systemic intravenous thrombolysis show the beginning of hemorrhagic transformation of the lentiform nucleus (arrow) and increasing hypoattenuation within the temporal lobe. Follow-up CT angiography demonstrated patency of the MCA, a finding that indicated successful thrombolysis. (e) CT scans obtained 2 days later show that the hemorrhage has increased in size (arrow). There is no infarction in the cortex of the MCA territory except in the temporal lobe.

View larger version (49K): [in a new window]   Figure 12a.  (a) Initial nonenhanced CT scans obtained 3 hours after the onset of stroke in a 77-year-old woman show effacement of the sulci in the area of the left MCA territory (black arrows) as well as "loss" of the insular ribbon (white arrow) and a hyperattenuating proximal MCA (arrowhead). (b) Perfusion CT study shows nonperfusion of the left MCA territory. On the TTP maps, the residual parts of the left hemisphere have a different color than the right hemisphere, a finding that indicates slight prolongation of TTP, which was calculated at about 1 second. (c) MIP images (left frontolateral view) and an SSD image (superior view) (far right) from CT angiography show proximal occlusion of the left MCA (white arrow) as well as occlusion of the left ICA (arrowhead). Note that the posterior cerebral arteries are predominantly supplied by the posterior communicating arteries (black arrows). This is a common anatomic variant and explains why the subtle TTP prolongation includes the territory of the posterior cerebral artery. (d) Nonenhanced CT scans obtained 1 day later show hypoattenuating swelling in the left MCA territory.