Figure 1.
Schematic diagram illustrating the segments of the vertebral artery (VA) and subclavian artery (SA).
V1 begins from the origin of VA to where it enters the transverse foramina at the fifth or sixth cervical vertebra. V2 begins from the level of the fifth or sixth cervical to the second cervical vertebra travelling through the transverse foramina at each vertebral level. V3 extends between the C2 transverse process and ends at the base of the skull where it enters the foramen magnum. V4 extends from the point at which the arteries enter the dura to the termination of both VAs at the vertebrobasilar junction. S1 begins the origin of SA and ends just proximal to the origin of SA. S2 begins just proximal to the origin of SA and ends the medial border of the scalenus anterior. S3 extends from the medial border of scalenus anterior to the outer border of the first rib.
Figure 2.
Schematic diagram illustrating the segments of the internal carotid artery (ICA).
C1 (cervical segment) begins at the level of the common carotid artery bifurcation to the entrance level of the carotid canal. C2 (petrous segment) extends within the carotid canal. C3 (lacerum segment) begins where the carotid canal ends and ends at the superior margin of the petrolingual ligament. C4 (cavernous segment) is surrounded by the cavernous sinus. C5 (clinoid segment) begins at the proximal dural ring and ends at the distal dural ring where the ICA extends through the medial side of anterior clinoid process. C6 (ophthalmic segment) begins at the distal dural ring and ends just proximal to the origin of the posterior communicating artery (PComA). C7 (communicating segment) begins just proximal to the origin of the PComA and ends at the ICA bifurcation.
Figure 3.
Mean arterial attenuation values and standard deviations (error bars) were measured at different locations in the two groups.
The numbers under the bars represent the numbers of arterial segments of each location. Mean attenuation values of SA, CB and CS of Group II were significantly higher than those of Group I (P=0.009, 0.025, 0.039 respectively). AA=aortic arch, SA=subclavian artery, CB=bifurcation of common carotid artery, CS= carotid siphon, M=M1 segment of middle cerebral artery, BA=basilar artery.
Figure 4.
Mean venous attenuation values and standard deviations (error bars) were measured at different locations in the two groups.
The numbers under the bars represent the numbers of venous segments of each location. Mean attenuations of SVC, IJVcontra and SS of Group II were significantly higher than those of Group I (P=0.034, 0.009, 0.001 respectively). SVC= superior vena cava, IJVcontra=internal jugular vein on the contralateral side of contrast medium injection, SS=straight sinus.
Figure 5.
Examples of intracranial arterial and venous enhancement patterns in the two groups.
Sagittal 25mm MIP (A) and transverse 1 mm MPR (B) of a patient from Group I show mild enhancement in intracranial veins. ROI-based measurement (B) reveals a vessel density of 104.7±4.3 HU in the SS (thick arrow) at the level of the BA (thin arrow) which had a vessel density of 308.1±18.6. Sagittal 25 mm MIP (C) and transverse 1 mm MPR (D) of a patient from Group II show marked venous enhancement of intracranial veins. The Vessel density of SS (D, thich arrow) is 266.2±19.6 HU at the level of the BA (thin arrow) which had a vessel density of 290.4±29.6. MIP= maximum intensity projection, MPR= multiplanar reformation, SS=straight sinus, BA=basilar artery.
Figure 6.
Examples of image quality of the Circle of Willis.
(A) The 30 mm MIP image of a 66-year-old man weight 66 kg in Group II. The distal branches of the middle cerebral arteries are demonstrated clearly and it is considered as score 4. (B) The 30 mm MIP image of a 55-year-old man weight 85.5 kg in Group I. The branches of middle cerebral arteries are not clearly demonstrated and it is considered as score 3. MIP= maximum intensity projection.
Figure 7.
Qualitative evaluations of streak artifacts of residual CM on the ipsilateral side of injection in the two groups.
(A) In Group I, the relative frequencies of score 1, 2 and 3 for the subclavian veins (SVipsi) are 3% (1/31), 29% (9/31) and 68% (21/31), respectively. In Group II, the relative frequencies of score 1, 2 and 3 for the SVipsi are 22% (5/23), 30% (7/23) and 48% (11/23), respectively. (B) In Group I, the relative frequencies of score 1, 2 and 3 for the internal jugular veins (IJVipsi) are 32% (10/31), 49% (15/31) and 19% (6/31), respectively. In Group II, the relative frequencies of score 1, 2 and 3 for the IJVipsi are 48% (11/23), 48% (11/23) and 4% (1/23), respectively. CM= contrast medium.
Figure 8.
Examples of streak artifacts caused by residual CM in the veins on the ipsilateral side of injection.
Coronal 25 mm MIP (A) of a patient from Group I shows a little residual CM in the left SV (arrow). His transversal 1 mm MPR (B) shows no residual CM in the left IJV (arrow). Coronal 25 mm MIP (C) and transversal 1 mm MPR (D) of a patient from Group II show large amount of CM in the left SV (thin arrow) and IJV (thick arrow) impairing evaluation of adjacent vessels. CM=contrast medium, MIP=maximum intensity projection, MPR=multiplanar reformation, SV= subclavian vein, IJV= internal jugular vein.
Figure 9.
Mean scores and standard deviations (error bars) on evaluation of bone remnants (A) and vessel integrity (B) after dual-energy bone removal in the two groups.
The numbers under the bars represent the numbers of arterial segments of each location. Group I has significantly higher mean scores of S2 segments for vessel integrity compared with that of Group II (P=0.019). AA=aortic arch, BCT=branchiocephalic trunk, S1-3=different segments of subclavian artery, ECA=external carotid artery and branches, CCA= common carotid artery, CB=bifurcation of CCA, C1-7=different segments of the internal carotid artery, ACA=anterior cerebral artery, MCA=middle cerebral artery, PCA=posterior cerebral artery, V1-4=different segments of the vertebral artery, BA=basilar artery.
Figure 10.
Examples of vessel integrity after dual-energy bone-removal postprocessing in the shoulder regions.
The coronal 25 mm MIP before BR (A) of a 42-year-old man weight 85 kg in Group II shows significant streak artifacts in shoulders (arrow), and little residual CM in bilateral SV. His thick MIP image after BR (B) shows most of the bilateral S3 segments and left S2 segment (arrow) were deleted by mistake. The Coronal 25 mm MIP before BR (C) of a 48-year-old man weight 60 kg in Group II shows significant residual CM in the left SV (arrow), but the streak artifacts in shoulders were not obviously. His thick MIP image after BR (D) shows that the left S3 segment was deleted (arrow) by mistake. The coronal 25 mm MIP before BR (E) of a 53-year-old man weight 65 kg in Group I shows a little streak artifacts in shoulders and residual CM in the right SV (arrow). Arterial vessels in shoulders were complete in his thick MIP after BR (F). MIP= maximum intensity projection, BR=bone removal, CM= contrast medium, SV= subclavian vein, IJV= internal jugular vein. S1, S2 and S3=different segments of subclavian artery.