Surg Radiol Anat DOI 10.1007/s00276-013-1246-6
Original Article
Prevalence of arterial branches arising from the extracranial internal carotid artery on CT angiography Juan E. Small · Justin Harrington · Evan Watkins
Received: 30 August 2013 / Accepted: 10 December 2013 © Springer-Verlag France 2013
Abstract Although it is well known that arterial branches may rarely arise from the cervical internal carotid artery (ICA), their incidence has not been adequately evaluated on computed tomography angiography (CTA). We investigate the prevalence of congenital and non-congenital anomalous branches arising from the cervical ICA by a 5 year retrospective review of neck CTAs performed on 2,602 patients. We found a higher frequency of arteries arising from the ICA than suggested by the existing literature, including a 0.49 % prevalence of the occipital artery origin and a 6.25 % prevalence of the superior pharyngeal branch of (the pharyngeal trunk of) the ascending pharyngeal artery. In addition, six cases of recanalized intersegmental arteries providing collateral flow to the cervical ICA from the cervical vertebral artery were identified. This is the first large, retrospective CTA study evaluating the incidence of these anomalous vessel origins. Keywords Internal carotid artery · Anatomic variants · CT angiography
J. E. Small (*) Tufts University School of Medicine, Lahey Clinic, 41 Mall Road, Burlington, MA 01805, USA e-mail: [email protected]
Introduction Although various case reports and pictorial essays of arterial branches arising from the extracranial internal carotid artery (ICA) exist, little precise information as to the frequency of such variations is present in the literature. Attention has been placed on persistent fetal carotidvertebrobasilar anastomoses such as otic, hypoglossal and proatlantal arteries. However, careful CTA analysis of other congenital and non-congenital branches is conspicuously absent. In the very recent literature, the first three-dimensional CTA study of the incidence of the occipital arteries arising from the ICA was performed, although only a small sample of 265 patients was examined, and no other branches were evaluated [7]. A recent, large-scale study of the incidence of the occipital artery arising from the ICA was performed on MRA without attention to other smaller branches [8]. The scant and small sample literature relating to the prevalence of branches arising from the extracranial ICA has led to a notion that these branches are exceedingly rare. However, a large-scale study on an imaging modality such as CTA that would detect small branches has not been performed to date. As ICA variants may alter surgical or embolization procedures, a study of this type is necessary [2–4]. The purpose of this study was to determine the prevalence of congenital and non-congenital arterial branches arising from the extracranial ICA as evaluated by CT angiography.
J. Harrington Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
Materials and methods
E. Watkins Lahey Clinic, 41 Mall Road, Burlington, MA 01805, USA
We retrospectively reviewed 3,079 computed tomography angiograms performed on 2,677 patients at our
13
Surg Radiol Anat
institution between January 2nd 2007 and May 31st 2012. The study was performed in accordance with institutional review board approval. A total of 75 records was excluded due to poor quality of images or failure to fully obtain the imaging record. We ultimately reviewed and analyzed the CTA images of 2,602 patients (1,444 males and 1,158 females; age range 14–101 years with a mean age of 64.47, median of 66 and SD of 19.36). Due to the retrospective nature of this experiment, informed consent was not obtained. All patients were examined on a GE LightSpeed 64-slice scanner or a Philips iCT 256-slice scanner. The standard protocol was intravenous injection of 80 cc non-ionic contrast with imaging from the aortic arch to the level of the apex of the calvarium with CTA source image width of 0.63 mm. The extracranial bilateral internal carotid arteries were closely inspected on CTA source images for the presence of any clearly identified, unequivocal arterial branch origin measuring 0.63 mm or greater arising from the cervical internal carotid arteries. Any arterial vessel origins emanating from the carotid bifurcation or within 3 mm from the origin were excluded as the aim of this study was to focus on branches arising from the cervical ICA proper and not from the bifurcation. Any candidate vessels without a clearly identified origin unquestionably arising from the ICA as assessed by the first author, an experienced neuroradiologist, were excluded from the analysis. This was done in an effort to exclude any confounding vessels coursing adjacent to the ICA as well as any vasa vasorum vessels. Any scans limiting evaluation due to poor contrast opacification, motion artifact, or metallic artifact obscuring areas of interest were excluded from analysis. If an ICA was either occluded without reconstitution or carotid body tumors were present, these cases were excluded from the study. In addition to evaluation of arterial origins, any ICA stenosis measured as mild (
Original Article
Prevalence of arterial branches arising from the extracranial internal carotid artery on CT angiography Juan E. Small · Justin Harrington · Evan Watkins
Received: 30 August 2013 / Accepted: 10 December 2013 © Springer-Verlag France 2013
Abstract Although it is well known that arterial branches may rarely arise from the cervical internal carotid artery (ICA), their incidence has not been adequately evaluated on computed tomography angiography (CTA). We investigate the prevalence of congenital and non-congenital anomalous branches arising from the cervical ICA by a 5 year retrospective review of neck CTAs performed on 2,602 patients. We found a higher frequency of arteries arising from the ICA than suggested by the existing literature, including a 0.49 % prevalence of the occipital artery origin and a 6.25 % prevalence of the superior pharyngeal branch of (the pharyngeal trunk of) the ascending pharyngeal artery. In addition, six cases of recanalized intersegmental arteries providing collateral flow to the cervical ICA from the cervical vertebral artery were identified. This is the first large, retrospective CTA study evaluating the incidence of these anomalous vessel origins. Keywords Internal carotid artery · Anatomic variants · CT angiography
J. E. Small (*) Tufts University School of Medicine, Lahey Clinic, 41 Mall Road, Burlington, MA 01805, USA e-mail: [email protected]
Introduction Although various case reports and pictorial essays of arterial branches arising from the extracranial internal carotid artery (ICA) exist, little precise information as to the frequency of such variations is present in the literature. Attention has been placed on persistent fetal carotidvertebrobasilar anastomoses such as otic, hypoglossal and proatlantal arteries. However, careful CTA analysis of other congenital and non-congenital branches is conspicuously absent. In the very recent literature, the first three-dimensional CTA study of the incidence of the occipital arteries arising from the ICA was performed, although only a small sample of 265 patients was examined, and no other branches were evaluated [7]. A recent, large-scale study of the incidence of the occipital artery arising from the ICA was performed on MRA without attention to other smaller branches [8]. The scant and small sample literature relating to the prevalence of branches arising from the extracranial ICA has led to a notion that these branches are exceedingly rare. However, a large-scale study on an imaging modality such as CTA that would detect small branches has not been performed to date. As ICA variants may alter surgical or embolization procedures, a study of this type is necessary [2–4]. The purpose of this study was to determine the prevalence of congenital and non-congenital arterial branches arising from the extracranial ICA as evaluated by CT angiography.
J. Harrington Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
Materials and methods
E. Watkins Lahey Clinic, 41 Mall Road, Burlington, MA 01805, USA
We retrospectively reviewed 3,079 computed tomography angiograms performed on 2,677 patients at our
13
Surg Radiol Anat
institution between January 2nd 2007 and May 31st 2012. The study was performed in accordance with institutional review board approval. A total of 75 records was excluded due to poor quality of images or failure to fully obtain the imaging record. We ultimately reviewed and analyzed the CTA images of 2,602 patients (1,444 males and 1,158 females; age range 14–101 years with a mean age of 64.47, median of 66 and SD of 19.36). Due to the retrospective nature of this experiment, informed consent was not obtained. All patients were examined on a GE LightSpeed 64-slice scanner or a Philips iCT 256-slice scanner. The standard protocol was intravenous injection of 80 cc non-ionic contrast with imaging from the aortic arch to the level of the apex of the calvarium with CTA source image width of 0.63 mm. The extracranial bilateral internal carotid arteries were closely inspected on CTA source images for the presence of any clearly identified, unequivocal arterial branch origin measuring 0.63 mm or greater arising from the cervical internal carotid arteries. Any arterial vessel origins emanating from the carotid bifurcation or within 3 mm from the origin were excluded as the aim of this study was to focus on branches arising from the cervical ICA proper and not from the bifurcation. Any candidate vessels without a clearly identified origin unquestionably arising from the ICA as assessed by the first author, an experienced neuroradiologist, were excluded from the analysis. This was done in an effort to exclude any confounding vessels coursing adjacent to the ICA as well as any vasa vasorum vessels. Any scans limiting evaluation due to poor contrast opacification, motion artifact, or metallic artifact obscuring areas of interest were excluded from analysis. If an ICA was either occluded without reconstitution or carotid body tumors were present, these cases were excluded from the study. In addition to evaluation of arterial origins, any ICA stenosis measured as mild (
