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Computerized Tomographic Angiography Scan following Carotid Endarterectomy
Computerized Tomographic Angiography Scan following Carotid Endarterectomy Be´atrice Marro, MD, Abderrezak Zouaoui, MD, Fabien Koskas, MD, Mokrane Sahel, MD, Samia Belkacem, MD, Isabelle Bonan, MD, Claude Marsault, MD, and Edouard Kieffer, MD, Paris, France
The purpose of this study was to evaluate the role of computed tomographic angiography (CTA) for postoperative assessment of carotid endarterectomy (CE). Twenty carotid endarterectomies were performed and controlled by using (1) intraoperative angiography, (2) postoperative duplex scanning and CTA with multiprojection volume reconstruction (MPVR). Intraoperative angiographic controls were deemed satisfactory for all patients. In 12 patients, the postoperative morphological aspect was satisfactory with CTA and duplex scanning. In the eight remaining patients, CTA and/or duplex scanning revealed 12 abnormalities: 3 were equally visualized on CTA and duplex scanning, 6 only on CTA and 3 only on duplex scanning. CTA is a rapid and noninvasive technique allowing the surgeon to get informative and comparative data. It might be an interesting alternative to postoperative angiography. (Ann Vasc Surg 1998;12:451-456.)
INTRODUCTION With the emergence and development of volume acquisition by spiral scanning, progress in scan imagery technique has made it possible to perform genuine computerized tomographic angiography (CTA), thus enhancing the exploration of blood vessels. That method has found wide applications in the exploration of cerebral vessels (Willis circle, neck vessels) on account of its innocuousness and sensitivity.1-8 In carotid surgery, the possibility of angiographic or ultrasonographic intraoperative anatomical control ensures the immediate correction of technical mishaps and thus helps reduce the rate of immediate reinterventions warranted by neurological accidents due to local thrombosis or an embolus from the operative seat. During the immediate postoperative period, the From the Service de Neuroradiologie et Service de Chirurgie Vasculaire, CHU Pitie´-Salpeˆtrie`re, Paris, France. Correspondence to: B. Marro, Service de Neuroradiologie du Professeur Marsault, CHU Pitie´-Salpeˆtrie`re, 47-83 Boulevard de l’Hoˆpital, 75651 Paris Cedex 13, France.
efficacy of the surgical procedure is also appraised through venous angiography, ultrasonography, and eminently arteriography. The latter yields the least disputable results, but is not a risk-free method of investigation, particularly in frail patients. That is why many teams prefer using ultrasonography or venous angiography for their postoperative controls, which lead to few reinterventions but are used instead as a database for further surveillance. In this study, we tested the hypothesis that angioscanning could become the method of reference, as being less invasive than arteriography, and at least as reliable as ultrasonography while providing valuable objective documents.
MATERIALS AND METHODS Twenty patients, eleven men and nine women, with ages ranging from 46 to 88 years old, underwent carotid endarterectomy (CE) for atheromatous stenosis. In all cases but one, these were eversion endarterectomies. All the CE were controlled through digital subtraction angiography, which allowed extemporaneous correction of the abnormalities that the surgeon deemed important. Prior 451
452
Marro et al.
Annals of Vascular Surgery
Fig. 1. Result without anomaly of a carotid endarterectomy: A MPVR reconstruction displayed in MIP mode, B surface reconstruction. Fig. 2. MPVR reconstruction: trouser-like customary aspect of the endarterectomized area.
to discharge, all patients underwent a morphological control by angioscanning and duplex scanning, respectively and independently carried out by a neuroradiologist and an angiologist. Angioscanning was performed in the spiral mode, on a square matrix of 512 × 512, with a collimation of 3 mm, a field of view of 15 cm, following the intravenous injection of 140 ml of contrast in a forearm vein, at a flow rate of 2,5 ml per sec. The time lag between the beginning of injection and acquisition was approximately 20 sec. The images acquired were reconstructed in 1 mm. The field of exploration, of less than 18 cm, extended from the C7-T1 vertebrae to the bottom of the sphenoid’s body (an indicator of the penetration of the internal carotid into the carotid canal). The time necessary for spiral acquisition did not exceed 60 sec. The reconstructed sections were then transferred onto an image-processing station (Advantage Windows, Spark 20, General Electric, Milwaukee, WI). Thanks to the Voxtool威 program, volume reconstruction was performed in multiprojection volume reconstruction (MPVR) mode, displayed in maximum intensity pixel (MIP) and in surface mode. Reconstruction time, per carotid, was approximately 10 min in MPVR mode, and 20 min in surface reconstruction mode.
RESULTS The last intraoperative angiographic controls have been deemed satisfactory by the surgeon in all
cases. In 12 patients the postoperative morphological aspect was satisfactory, with a regular expansion without either stenosis or detachment of the intima at the proximal and distal boundaries of the endarterectomized zone (Figs. 1 and 2). In the eight remaining patients, the angioscan or the postoperative ultrasonogram revealed 12 abnormalities (Table 1). None of these anomalies presented a degree of stenosis superior or equal to 50%. They included two nonstenosing intimal steps of the proximal and distal portions of the CE (Fig. 3); two intimal flaps of the common carotid; one distal intimal step on the internal carotid, which reduced the lumen by 30% (Fig. 4); one intimal flap at the origin of the external carotid; one irregular aspect of the external carotid; one occlusion of the external carotid 1 cm from its origin; one irregularity at the lower third of the endarterectomized surface (Fig. 5); two excentered intraluminal accretions of hypodense material stretching over the whole height of the endarterectomized area without any significant stenosis (Fig. 6) and an inconspicuous extrinsic narrowing of the circumference of the internal carotid by an inflammatory process associated with the resorption of a hematoma. Three abnormalities were visible both on angioscans and on ultrasonograms. The other modifications were displayed only by angioscans (six times) or by ultrasonograms (three times). It must be noted that a small intimal step of the common carotid, which was found through ul-
Vol. 12, No. 5, 1998
CTA scan following CE 453
Table I. Duplex scanning and CTA results Patient
Duplex scanning
1 2 3
WA WA WA
4
WA
5
WA
6 7 8
WA WA WA
9 10 11
12 13 14 15 16 17 18
WA WA Proximal intimal flap on the CC WA WA WA WA Irregularities of the EC WA WA
19
Intimal step on the CC
20
Intimal step at the tip of the bulb; intimal flap at the origin of the EC
Angioscanning
WA WA Inflammatory readjustments due to contact with a hematoma with intrinsic circumference narrowing of the IC Distal internal step of the IC with a 30% stenosis Thrombus accretion on the endarterectomized area; occlusion of the EC 1 cm from its origin WA 8 mm aneurysmal dilatation of the distal IC WA WA Proximal intimal flap on the CC WA WA WA WA WA WA Irregularity of the endarterectomized area Deglutition artifact on the image of the intimal step on the CC Intimal step on the CC, thrombus accretion on the endarterectomized surface, intimal step at the hip of the bulb with kinking
CC, common carotid; IC, internal carotid; TE, thromboendarterectomy; WA, without anomaly.
trasonography but not visualized in angioscanning, tallied with a zone in the angioscan that had been made uninterpretable, owing to a deglutition artifact.
DISCUSSION Postoperative complications following CE are well known, and more often than not are dependent on
a thromboembolic mechanism, against which the best safeguard is technical perfection of the surgical act. It is also generally admitted that minor morphological abnormalities after CE may constitute the starting point of a restenosis. Different anomalies may be encountered. These lesions can be located at the level of the three elements of the carotid bifurcation; they may be residual stenoses, extended irregularities of the endarterectomized area, steps and intimal flaps at the boundaries of the endarterectomy, and local accretions of thrombi.9-11 Currently, many surgeons control their operative results during the intervention proper by means of arteriography, angioscopy, or ultrasonography.10,12-14 The most important abnormalities are more and more often readily corrected immediately.10 In addition, the correction of minor residual anomalies is more controversial.9 These residual anomalies must be documented and monitored, because they may become the starting point of a restenosis. Even though arteriography is the instrument of reference of this early control,11 most surgeons prefer ultrasonography, on account of its simplicity and innocuousness.15,16 The most accurate morphological study is achieved by arteriography, but this method of investigation is costly, since it requires hospitalization, and is invasive, with a rate of neurological complications that could reach 12% in certain highrisk groups.2,17,18 For all these reasons, postoperative arteriography has been gradually abandoned in favor of duplex scanning. Duplex scanning is a noninvasive, reliable examination that allows a morphological and hemodynamic evaluation of the lesion in the carotid bifurcation. However, it is a dynamic examination, whose character as a ‘‘dependent operator’’ is widely acknowledged. Its results allow neither immediate analysis by an unexperienced physician, nor a retrospective study. In our study, angioscanning led to the discovery of twice as many abnormalities as duplex scanning. These anomalies, including mainly wall hematomata and perivascular inflammatory tissue adjustments, are easily investigated through angioscanning, thanks to visualization of vascular walls and of the structures contiguous to the vessel. Whereas local pain related to the scar may impede ultrasonography, and cutaneous suture staples or surgical clips contraindicate magnetic resonance imaging, immediate postoperative control through angioscanning is feasible under all circumstances. Millimetric axial sections are indispensable for a diagnostic analysis of details, and are the most informative for volume reconstruction. The MPVR mode allows the selection of a given volume of interest
454
Marro et al.
Annals of Vascular Surgery
Fig. 3. Case report no. 20: reconstruction in MPVR mode showing a kinking at the tip of the carotid bulb; A comprehensive view of the carotid bifurcation, B axial reconstruction of the internal carotid with a reduced volume of interest allowing a better visualization of anomalies. Fig. 4. Case report no. 4: A reconstructed axial image, B display in MPVR mode showing the distal intimal step of the internal carotid with a 30% stenosis.
and the display of high-intensity objects such as the contrast medium present in the vessel’s lumen. The finer the structure investigated, the smaller the volume used, and the more instructive the volume reconstruction displayed in MIP. Thus, the angioscanner detected the presence of an intimal flap at the level of the distal part of the endarterectomy, which neither the intraoperative angiography nor the postoperative duplex scanning had helped visualize. The intimal flap is clearly outlined, owing to the difference in density between the contrast medium opacified vascular lumen, and the hypodense intima. The contrast medium infiltrating every gap in the vessel’s wall also helps visualize clearly the irregularities of the arterial wall. The surface mode provides a relief image of the contrast medium present in the vessels. In our experience, this type of reconstruction, though more ‘‘eloquent’’ than the
MPVR, is much less useful because it demands image processing and thus alters information. In the literature, the rate of restenoses of over 50% is about 10% over 3 years, with peak occurrence during the first year.15,19,20 With angioscanning, the possibility to visualize the vascular wall and obtain reformated axial sections orthogonal to the axis of the vessel ensures the precise measurement of the degree of postoperative residual stenosis. Furthermore, the possibility to secure the same acquisition parameters and similar reconstruction parameters for a single patient allows one to carry out a comparative evolutive follow-up and therefore to appraise the evolution of minor residual anomalies. The main limitations to the use of angioscanning after a carotid endarterectomy are movement and deglutition artifacts that may prevent satisfactory
Vol. 12, No. 5, 1998
CTA scan following CE 455
Fig. 5. Case report no. 18: irregularity of the proximal portion of the endarterectomized area; A axial image, B reconstruction in reduced volume in MPVR mode. Fig. 6. Case report no. 5: accretion of hypodense material (thrombus), excentered on the endarterectomized area; A axial section, B MPVR reconstruction.
volume reconstruction and lead to an erroneous interpretation (as was the case concerning one of our patients). Angioscanning is a morphological examination that is fast, reliable, free from neurological risk, and that might constitute an alternative to postoperative arteriography because it provides clinicians with informative comparison documents, while being only slightly invasive. REFERENCES 1. Schwartz RB, Jones KM, Chernoff DM, et al. Common carotid artery bifurcation: evaluation with spiral CT. Work in progress. Radiology 1992;185:513-519. 2. Chervu A, Moore WS. Carotid endarterectomy without arteriography. Ann Vasc Surg 1994;8:296-302. 3. Link J, Brossmann J, Grabener M, et al. Spiral CT angiography and selective digital subtraction angiography of internal carotid artery stenosis. AJNR 1996;17:89-94.
4. Dillon EH, Van Leewen MS, Fernandez MA. CT angiography: application to the evaluation of carotid artery stenosis. Radiology 1993;189:211-219. 5. Alberico RA, Patel M, Casey S, et al. Evaluation of the circle of Willis with three-dimensional CT angiography in patients with suspected intracranial aneurysms. AJNR 1995;16: 1571-1578. 6. Dorsch NWC, Young N, Kingston RJ, et al. Early experience with spiral CT in the diagnosis of intracranial aneurysms. Neurosurgery 1995;36:230-236. 7. Tampieri D, Leblanc R, Oleszek, et al. Three-dimensional computed tomographic angiography of cerebral aneurysms. Neurosurgery 1995;36:749-755. 8. Grossi G, Romanzi F, Macchia G, et al. Angio-CT: a proposal for emergency diagnosis in subarachnoid hemorrhage as a preliminary to therapeutic choices. Intervent Neuroradiol 1995;1:43-57. 9. Courbier R. Arte´riographie per-ope´ratoire en chirurg´ie carotidienne. In Kieffer E, Natali J, eds. Aspects Techniques de la Chirurgie Carotidienne. Paris: AERCV, 1987, pp 71-78. 10. Donaldson MC, Ivarsson BL, Mannick JA, Whittemore AD.
456
11.
12.
13.
14. 15.
Marro et al.
Impact of completion angiography on operative conduct and results of carotid endaterectomy. Ann Surg 1993;6:682-687. Koskas F, Kieffer E, Bahnini A, Ruotolo C, Rancurel G. Endarte´riectomie carotidienne par e´version: re´sultats a` court et a` long terme. Ann Chir Vasc 1995;9:9-15. Lingenfelter KA, Fuller BC, Sullivan TM. Controˆle perope´ratoire en chirurgie carotidienne: comparison des techniques. Ann Chir Vasc 1995;9:235-240. Lohr JM, Albers B, Roat TW, et al. Effects of completion angiography on the outcome of carotid endarterectomy. Cardiovasc Surg 1995;3:299-305. Roon AJ, Hoogerwerf D. Intraoperative arteriography and carotid surgery. J Vasc Surg 1992;16:239-243. Ouriel K, Green RM. Appropriate frequency of carotid duplex testing following carotid endarterectomy. Am J Surg 1995;170:144-147.
Annals of Vascular Surgery
16. Maiuri F, Gallicchio B, Iaconetta G, D’Andrea F. The role of real time B-mode ultrasonography in the follow-up of patients submitted to carotid endaterectomy. J Neurosurg Sci 1992;36:73-77. 17. Franco CD, Goldsmith J, Veith FJ, et al. Management of arterial injuries produced by percutaneous femoral procedures. Surgery 1993;113:419-423. 18. Egglin TKP, O’Moore PV, Feinstein AR, Waltmann AC. Complications of peripheral arteriography: a new system to identify patients at increased risk. J Vasc Surg 1995;22:787794. 19. Kieny R, Seiller C, Petit H. Evolution of carotid restenosis after endarterectomy. Cardiovasc Surg 1994;2:555-560. 20. Mattos MA, Van Bemmelen PS, Barkmeier LD, et al. Routine surveillance after carotid endarterectomy: does it affect clinical management? J Vasc Surg 1993;17:819-830.
The purpose of this study was to evaluate the role of computed tomographic angiography (CTA) for postoperative assessment of carotid endarterectomy (CE). Twenty carotid endarterectomies were performed and controlled by using (1) intraoperative angiography, (2) postoperative duplex scanning and CTA with multiprojection volume reconstruction (MPVR). Intraoperative angiographic controls were deemed satisfactory for all patients. In 12 patients, the postoperative morphological aspect was satisfactory with CTA and duplex scanning. In the eight remaining patients, CTA and/or duplex scanning revealed 12 abnormalities: 3 were equally visualized on CTA and duplex scanning, 6 only on CTA and 3 only on duplex scanning. CTA is a rapid and noninvasive technique allowing the surgeon to get informative and comparative data. It might be an interesting alternative to postoperative angiography. (Ann Vasc Surg 1998;12:451-456.)
INTRODUCTION With the emergence and development of volume acquisition by spiral scanning, progress in scan imagery technique has made it possible to perform genuine computerized tomographic angiography (CTA), thus enhancing the exploration of blood vessels. That method has found wide applications in the exploration of cerebral vessels (Willis circle, neck vessels) on account of its innocuousness and sensitivity.1-8 In carotid surgery, the possibility of angiographic or ultrasonographic intraoperative anatomical control ensures the immediate correction of technical mishaps and thus helps reduce the rate of immediate reinterventions warranted by neurological accidents due to local thrombosis or an embolus from the operative seat. During the immediate postoperative period, the From the Service de Neuroradiologie et Service de Chirurgie Vasculaire, CHU Pitie´-Salpeˆtrie`re, Paris, France. Correspondence to: B. Marro, Service de Neuroradiologie du Professeur Marsault, CHU Pitie´-Salpeˆtrie`re, 47-83 Boulevard de l’Hoˆpital, 75651 Paris Cedex 13, France.
efficacy of the surgical procedure is also appraised through venous angiography, ultrasonography, and eminently arteriography. The latter yields the least disputable results, but is not a risk-free method of investigation, particularly in frail patients. That is why many teams prefer using ultrasonography or venous angiography for their postoperative controls, which lead to few reinterventions but are used instead as a database for further surveillance. In this study, we tested the hypothesis that angioscanning could become the method of reference, as being less invasive than arteriography, and at least as reliable as ultrasonography while providing valuable objective documents.
MATERIALS AND METHODS Twenty patients, eleven men and nine women, with ages ranging from 46 to 88 years old, underwent carotid endarterectomy (CE) for atheromatous stenosis. In all cases but one, these were eversion endarterectomies. All the CE were controlled through digital subtraction angiography, which allowed extemporaneous correction of the abnormalities that the surgeon deemed important. Prior 451
452
Marro et al.
Annals of Vascular Surgery
Fig. 1. Result without anomaly of a carotid endarterectomy: A MPVR reconstruction displayed in MIP mode, B surface reconstruction. Fig. 2. MPVR reconstruction: trouser-like customary aspect of the endarterectomized area.
to discharge, all patients underwent a morphological control by angioscanning and duplex scanning, respectively and independently carried out by a neuroradiologist and an angiologist. Angioscanning was performed in the spiral mode, on a square matrix of 512 × 512, with a collimation of 3 mm, a field of view of 15 cm, following the intravenous injection of 140 ml of contrast in a forearm vein, at a flow rate of 2,5 ml per sec. The time lag between the beginning of injection and acquisition was approximately 20 sec. The images acquired were reconstructed in 1 mm. The field of exploration, of less than 18 cm, extended from the C7-T1 vertebrae to the bottom of the sphenoid’s body (an indicator of the penetration of the internal carotid into the carotid canal). The time necessary for spiral acquisition did not exceed 60 sec. The reconstructed sections were then transferred onto an image-processing station (Advantage Windows, Spark 20, General Electric, Milwaukee, WI). Thanks to the Voxtool威 program, volume reconstruction was performed in multiprojection volume reconstruction (MPVR) mode, displayed in maximum intensity pixel (MIP) and in surface mode. Reconstruction time, per carotid, was approximately 10 min in MPVR mode, and 20 min in surface reconstruction mode.
RESULTS The last intraoperative angiographic controls have been deemed satisfactory by the surgeon in all
cases. In 12 patients the postoperative morphological aspect was satisfactory, with a regular expansion without either stenosis or detachment of the intima at the proximal and distal boundaries of the endarterectomized zone (Figs. 1 and 2). In the eight remaining patients, the angioscan or the postoperative ultrasonogram revealed 12 abnormalities (Table 1). None of these anomalies presented a degree of stenosis superior or equal to 50%. They included two nonstenosing intimal steps of the proximal and distal portions of the CE (Fig. 3); two intimal flaps of the common carotid; one distal intimal step on the internal carotid, which reduced the lumen by 30% (Fig. 4); one intimal flap at the origin of the external carotid; one irregular aspect of the external carotid; one occlusion of the external carotid 1 cm from its origin; one irregularity at the lower third of the endarterectomized surface (Fig. 5); two excentered intraluminal accretions of hypodense material stretching over the whole height of the endarterectomized area without any significant stenosis (Fig. 6) and an inconspicuous extrinsic narrowing of the circumference of the internal carotid by an inflammatory process associated with the resorption of a hematoma. Three abnormalities were visible both on angioscans and on ultrasonograms. The other modifications were displayed only by angioscans (six times) or by ultrasonograms (three times). It must be noted that a small intimal step of the common carotid, which was found through ul-
Vol. 12, No. 5, 1998
CTA scan following CE 453
Table I. Duplex scanning and CTA results Patient
Duplex scanning
1 2 3
WA WA WA
4
WA
5
WA
6 7 8
WA WA WA
9 10 11
12 13 14 15 16 17 18
WA WA Proximal intimal flap on the CC WA WA WA WA Irregularities of the EC WA WA
19
Intimal step on the CC
20
Intimal step at the tip of the bulb; intimal flap at the origin of the EC
Angioscanning
WA WA Inflammatory readjustments due to contact with a hematoma with intrinsic circumference narrowing of the IC Distal internal step of the IC with a 30% stenosis Thrombus accretion on the endarterectomized area; occlusion of the EC 1 cm from its origin WA 8 mm aneurysmal dilatation of the distal IC WA WA Proximal intimal flap on the CC WA WA WA WA WA WA Irregularity of the endarterectomized area Deglutition artifact on the image of the intimal step on the CC Intimal step on the CC, thrombus accretion on the endarterectomized surface, intimal step at the hip of the bulb with kinking
CC, common carotid; IC, internal carotid; TE, thromboendarterectomy; WA, without anomaly.
trasonography but not visualized in angioscanning, tallied with a zone in the angioscan that had been made uninterpretable, owing to a deglutition artifact.
DISCUSSION Postoperative complications following CE are well known, and more often than not are dependent on
a thromboembolic mechanism, against which the best safeguard is technical perfection of the surgical act. It is also generally admitted that minor morphological abnormalities after CE may constitute the starting point of a restenosis. Different anomalies may be encountered. These lesions can be located at the level of the three elements of the carotid bifurcation; they may be residual stenoses, extended irregularities of the endarterectomized area, steps and intimal flaps at the boundaries of the endarterectomy, and local accretions of thrombi.9-11 Currently, many surgeons control their operative results during the intervention proper by means of arteriography, angioscopy, or ultrasonography.10,12-14 The most important abnormalities are more and more often readily corrected immediately.10 In addition, the correction of minor residual anomalies is more controversial.9 These residual anomalies must be documented and monitored, because they may become the starting point of a restenosis. Even though arteriography is the instrument of reference of this early control,11 most surgeons prefer ultrasonography, on account of its simplicity and innocuousness.15,16 The most accurate morphological study is achieved by arteriography, but this method of investigation is costly, since it requires hospitalization, and is invasive, with a rate of neurological complications that could reach 12% in certain highrisk groups.2,17,18 For all these reasons, postoperative arteriography has been gradually abandoned in favor of duplex scanning. Duplex scanning is a noninvasive, reliable examination that allows a morphological and hemodynamic evaluation of the lesion in the carotid bifurcation. However, it is a dynamic examination, whose character as a ‘‘dependent operator’’ is widely acknowledged. Its results allow neither immediate analysis by an unexperienced physician, nor a retrospective study. In our study, angioscanning led to the discovery of twice as many abnormalities as duplex scanning. These anomalies, including mainly wall hematomata and perivascular inflammatory tissue adjustments, are easily investigated through angioscanning, thanks to visualization of vascular walls and of the structures contiguous to the vessel. Whereas local pain related to the scar may impede ultrasonography, and cutaneous suture staples or surgical clips contraindicate magnetic resonance imaging, immediate postoperative control through angioscanning is feasible under all circumstances. Millimetric axial sections are indispensable for a diagnostic analysis of details, and are the most informative for volume reconstruction. The MPVR mode allows the selection of a given volume of interest
454
Marro et al.
Annals of Vascular Surgery
Fig. 3. Case report no. 20: reconstruction in MPVR mode showing a kinking at the tip of the carotid bulb; A comprehensive view of the carotid bifurcation, B axial reconstruction of the internal carotid with a reduced volume of interest allowing a better visualization of anomalies. Fig. 4. Case report no. 4: A reconstructed axial image, B display in MPVR mode showing the distal intimal step of the internal carotid with a 30% stenosis.
and the display of high-intensity objects such as the contrast medium present in the vessel’s lumen. The finer the structure investigated, the smaller the volume used, and the more instructive the volume reconstruction displayed in MIP. Thus, the angioscanner detected the presence of an intimal flap at the level of the distal part of the endarterectomy, which neither the intraoperative angiography nor the postoperative duplex scanning had helped visualize. The intimal flap is clearly outlined, owing to the difference in density between the contrast medium opacified vascular lumen, and the hypodense intima. The contrast medium infiltrating every gap in the vessel’s wall also helps visualize clearly the irregularities of the arterial wall. The surface mode provides a relief image of the contrast medium present in the vessels. In our experience, this type of reconstruction, though more ‘‘eloquent’’ than the
MPVR, is much less useful because it demands image processing and thus alters information. In the literature, the rate of restenoses of over 50% is about 10% over 3 years, with peak occurrence during the first year.15,19,20 With angioscanning, the possibility to visualize the vascular wall and obtain reformated axial sections orthogonal to the axis of the vessel ensures the precise measurement of the degree of postoperative residual stenosis. Furthermore, the possibility to secure the same acquisition parameters and similar reconstruction parameters for a single patient allows one to carry out a comparative evolutive follow-up and therefore to appraise the evolution of minor residual anomalies. The main limitations to the use of angioscanning after a carotid endarterectomy are movement and deglutition artifacts that may prevent satisfactory
Vol. 12, No. 5, 1998
CTA scan following CE 455
Fig. 5. Case report no. 18: irregularity of the proximal portion of the endarterectomized area; A axial image, B reconstruction in reduced volume in MPVR mode. Fig. 6. Case report no. 5: accretion of hypodense material (thrombus), excentered on the endarterectomized area; A axial section, B MPVR reconstruction.
volume reconstruction and lead to an erroneous interpretation (as was the case concerning one of our patients). Angioscanning is a morphological examination that is fast, reliable, free from neurological risk, and that might constitute an alternative to postoperative arteriography because it provides clinicians with informative comparison documents, while being only slightly invasive. REFERENCES 1. Schwartz RB, Jones KM, Chernoff DM, et al. Common carotid artery bifurcation: evaluation with spiral CT. Work in progress. Radiology 1992;185:513-519. 2. Chervu A, Moore WS. Carotid endarterectomy without arteriography. Ann Vasc Surg 1994;8:296-302. 3. Link J, Brossmann J, Grabener M, et al. Spiral CT angiography and selective digital subtraction angiography of internal carotid artery stenosis. AJNR 1996;17:89-94.
4. Dillon EH, Van Leewen MS, Fernandez MA. CT angiography: application to the evaluation of carotid artery stenosis. Radiology 1993;189:211-219. 5. Alberico RA, Patel M, Casey S, et al. Evaluation of the circle of Willis with three-dimensional CT angiography in patients with suspected intracranial aneurysms. AJNR 1995;16: 1571-1578. 6. Dorsch NWC, Young N, Kingston RJ, et al. Early experience with spiral CT in the diagnosis of intracranial aneurysms. Neurosurgery 1995;36:230-236. 7. Tampieri D, Leblanc R, Oleszek, et al. Three-dimensional computed tomographic angiography of cerebral aneurysms. Neurosurgery 1995;36:749-755. 8. Grossi G, Romanzi F, Macchia G, et al. Angio-CT: a proposal for emergency diagnosis in subarachnoid hemorrhage as a preliminary to therapeutic choices. Intervent Neuroradiol 1995;1:43-57. 9. Courbier R. Arte´riographie per-ope´ratoire en chirurg´ie carotidienne. In Kieffer E, Natali J, eds. Aspects Techniques de la Chirurgie Carotidienne. Paris: AERCV, 1987, pp 71-78. 10. Donaldson MC, Ivarsson BL, Mannick JA, Whittemore AD.
456
11.
12.
13.
14. 15.
Marro et al.
Impact of completion angiography on operative conduct and results of carotid endaterectomy. Ann Surg 1993;6:682-687. Koskas F, Kieffer E, Bahnini A, Ruotolo C, Rancurel G. Endarte´riectomie carotidienne par e´version: re´sultats a` court et a` long terme. Ann Chir Vasc 1995;9:9-15. Lingenfelter KA, Fuller BC, Sullivan TM. Controˆle perope´ratoire en chirurgie carotidienne: comparison des techniques. Ann Chir Vasc 1995;9:235-240. Lohr JM, Albers B, Roat TW, et al. Effects of completion angiography on the outcome of carotid endarterectomy. Cardiovasc Surg 1995;3:299-305. Roon AJ, Hoogerwerf D. Intraoperative arteriography and carotid surgery. J Vasc Surg 1992;16:239-243. Ouriel K, Green RM. Appropriate frequency of carotid duplex testing following carotid endarterectomy. Am J Surg 1995;170:144-147.
Annals of Vascular Surgery
16. Maiuri F, Gallicchio B, Iaconetta G, D’Andrea F. The role of real time B-mode ultrasonography in the follow-up of patients submitted to carotid endaterectomy. J Neurosurg Sci 1992;36:73-77. 17. Franco CD, Goldsmith J, Veith FJ, et al. Management of arterial injuries produced by percutaneous femoral procedures. Surgery 1993;113:419-423. 18. Egglin TKP, O’Moore PV, Feinstein AR, Waltmann AC. Complications of peripheral arteriography: a new system to identify patients at increased risk. J Vasc Surg 1995;22:787794. 19. Kieny R, Seiller C, Petit H. Evolution of carotid restenosis after endarterectomy. Cardiovasc Surg 1994;2:555-560. 20. Mattos MA, Van Bemmelen PS, Barkmeier LD, et al. Routine surveillance after carotid endarterectomy: does it affect clinical management? J Vasc Surg 1993;17:819-830.