The usefulness of 3D-CT angiography for the diagnosis of spontaneous vertebral artery dissection-report of two cases

CT versus MR Techniques in the Detection of Cervical Artery Dissection

BACKGROUND

Spontaneous cervical artery dissection (sCAD) is an important etiology of juvenile stroke. The gold standard for the diagnosis of sCAD is convential angiography. However, magnetic resonance imaging (MRI)/MR angiography (MRA) and computed tomography (CT)/CT angiography (CTA) are frequently used alternatives. New developments such as multislice CT/CTA have enabled routine acquisition of thinner sections with rapid imaging times. The goal of this study was to compare the capability of recent developed 128-slice CT/CTA to MRI/MRA to detect radiologic features of sCAD.

METHODS

Retrospective review of patients with suspected sCAD (n = 188) in a database of our Stroke center (2008-2014), who underwent CT/CTA and MRI/MRA on initial clinical work-up. A control group of 26 patients was added. All Images were evaluated concerning specific and sensitive radiological features for dissection by two experienced neuroradiologists. Imaging features were compared between the two modalities.

RESULTS

Forty patients with 43 dissected arteries received both modalities (29 internal carotid arteries [ICAs] and 14 vertebral arteries [VAs]). All CADs were identified in CT/CTA and MRI/MRA. The features intimal flap, stenosis, and lumen irregularity appeared in both modalities. One high-grade stenosis was identified by CT/CTA that was expected occluded on MRI/MRA. Two MRI/MRA-confirmed pseudoaneurysms were missed by CT/CTA. None of the controls evidenced specific imaging signs for dissection.

CONCLUSIONS

CT/CTA is a reliable and better available alternative to MRI/MRA for diagnosis of sCAD. CT/CTA should be used to complement MRI/MRA in cases where MRI/MRA suggests occlusion.

Improved delineation of arteries in the posterior fossa of the brain by model-based iterative reconstruction in volume-rendered 3D CT angiography

BACKGROUND AND PURPOSE

Improved CTA delineation of arteries and unruptured aneurysms is clinically desired in the posterior fossa. We present a novel model-based iterative reconstruction that models system statistics and optics to improve CT image quality. We investigated the utility of MBIR for improving delineation of arteries in the posterior fossa on 3D brain CTA.

MATERIALS AND METHODS

Using filtered back-projection with a standard kernel and MBIR, we reconstructed axial images of 0.625-mm thickness of 28 consecutive patients (14 men; mean age, 58.6 ± 14.6 years) who underwent 64-detector brain CTA. We placed regions of interest on the axial images, measured the mean CT value in the basilar artery and the value and SD in the pons and bilateral cerebellar hemispheres, and calculated the contrast-to-noise ratio of the brain arteries in the posterior fossa. Using volume-rendered CTA and a 4-point scale, 2 radiologists independently graded delineation of the BA, bilateral vertebral artery, superior cerebellar artery, and anterior and posterior inferior cerebellar arteries. We compared the results between FBP and MBIR by using paired t and Wilcoxon signed-rank tests.

RESULTS

Compared with FBP, MBIR significantly improved the contrast-to-noise ratio (P < .0001) and subjective delineation of all arteries in the posterior fossa except the BA (VA, SCA, AICA, and PICA; P < .05 for all). The mean visual score by MBIR was 3.0 or higher for all those arteries except the AICA assessed by reader 1 (2.6 ± 0.7).

CONCLUSIONS

With 3D brain CTA, contrast-to-noise ratio and arterial delineation of the VA, SCA, AICA, and PICA in the posterior fossa are better with MBIR than FBP.

Multidetector computed tomography angiography: Application in vertebral artery dissection

BACKGROUND AND PURPOSE

Multidetector computed tomography angiography (MDCTA) is a minimally invasive radiological technique providing high-resolution images of the arterial wall and angiographic images of the lumen. We studied the radiological features of vertebral artery dissection (VAD) in a consecutive series of patients investigated for acute stroke and subarachnoid hemorrhage (SAH) in order to confirm and define the diagnostic features of VAD on MDCTA.

PATIENTS AND METHODS

Review of patients identified prospectively over a 4-year period with VAD assessed by MDCTA was conducted. Radiological features of VAD on MDCTA were reanalyzed utilising previously reported criteria for VAD.

RESULTS

Thirty-five patients (25 males, mean age 49.6 years) with a total of 45 dissected vertebral arteries were reviewed. MDCTA features of VAD included increased wall thickness in 44/45 (97.7%) arteries and increased total vessel diameter in 42/45 arteries (93.3%). All dissected arteries had either lumen stenosis (21/45) or associated segmental occlusion (24/45). An intimal flap was detected in 6/45 (13.3 %) vessels. Twenty-five patients had follow-up imaging, 14/32 vessels returned to normal, 4 showed improvement in stenosis but did not return to normal and 14 demonstrated no change. The majority of non-occluded vessels became normal or displayed improved patency. Only 4/17 occluded arteries demonstrated re-establishment of flow. No adverse effects were recorded.

CONCLUSIONS

MDCTA is a safe and reliable technique for the diagnosis of VAD. Increased wall thickness (97.7%) and increased vessel wall diameter (93.3%) were the most frequently observed features.

Comparison of multidetector CT angiography and MR imaging of cervical artery dissection

BACKGROUND AND PURPOSE

Conventional angiography has been historically considered the gold standard for the diagnosis of cervical artery dissection, but MR imaging/MR angiography (MRA) and CT/CT angiography (CTA) are commonly used noninvasive alternatives. The goal of this study was to compare the ability of multidetector CT/CTA and MR imaging/MRA to detect common imaging findings of dissection.

MATERIALS AND METHODS

Patients in the data base of our Stroke Center between 2003 and 2007 with dissections who had CT/CTA and MR imaging/MRA on initial work-up were reviewed retrospectively. Two neuroradiologists evaluated the images for associated findings of dissection, including acute ischemic stroke, luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap. The readers also subjectively rated each vessel on the basis of whether the imaging findings were more clearly displayed with CT/CTA or MR imaging/MRA or were equally apparent.

RESULTS

Eighteen patients with 25 dissected vessels (15 internal carotid arteries [ICA] and 10 vertebral arteries [VA]) met the inclusion criteria. CT/CTA identified more intimal flaps, pseudoaneurysms, and high-grade stenoses than MR imaging/MRA. CT/CTA was preferred for diagnosis in 13 vessels (5 ICA, 8 VA), whereas MR imaging/MRA was preferred in 1 vessel (ICA). The 2 techniques were deemed equal in the remaining 11 vessels (9 ICA, 2 VA). A significant preference for CT/CTA was noted for VA dissections (P < .05), but not for ICA dissections.

CONCLUSION

Multidetector CT/CTA visualized more features of cervical artery dissection than MR imaging/MRA. CT/CTA was subjectively favored for vertebral dissection, whereas there was no technique preference for ICA dissection. In many cases, MR imaging/MRA provided complementary or confirmatory information, particularly given its better depiction of ischemic complications.

State of the art: noninvasive imaging and management of neurovascular trauma

Neurotrauma represents a significant public health problem, accounting for a significant proportion of the morbidity and mortality associated with all traumatic injuries. Both blunt and penetrating injuries to cervicocerebral vessels are significant and are likely more common than previously recognized. Imaging of such injuries is an important component in the evaluation of individuals presenting with such potential injuries, made all the more important since many of the vascular injuries are clinically silent. Management of injuries, particularly those caused by blunt trauma, is constantly evolving. This article addresses the current state of imaging and treatment of such injuries.

Radiological findings for arterial dissection of the anterior cerebral artery

We treated a patient with anterior cerebral artery (ACA) dissection that caused an ischaemic stroke, and investigated serial changes over time by using three different radiological methods. The conventional angiography findings for ACA dissection corresponded to those of computed tomography (CT) angiography, but not those of magnetic resonance angiography for each phase. We presume that the results were based on the velocity of the blood flow in the pseudolumen of the dissected artery, and we believe that CT angiography is a useful and less invasive diagnostic tool for intracranial arterial dissection.

Two cases of spontaneous middle cerebral arterial dissection causing ischemic stroke

Spontaneous middle cerebral arterial dissection (MCAD) is a rare cause of ischemic stroke. We report two cases of isolated spontaneous MCAD causing ischemic stroke. MCAD should be considered when a young patient has a middle cerebral artery territory infarct with stenosis at the origin of the middle cerebral artery. We discuss noninvasive radiological techniques for the diagnosis of MCAD.

Anomalous vertebral artery at the extraosseous and intraosseous regions of the craniovertebral junction: analysis by three-dimensional computed tomography angiography

STUDY DESIGN

This study examined the extraosseous and intraosseous anomalies of vertebral arteries in patients who underwent surgery of the craniovertebral junction.

OBJECTIVES

To describe the usefulness of three-dimensional computed tomography angiography for evaluating vertebral artery anomalies before surgery.

SUMMARY OF BACKGROUND DATA

Previous studies using catheter angiograms have identified anomalous courses of the vertebral artery at the craniovertebral junction. Studies using computed tomography reconstruction also showed deviation of the vertebral artery groove at the C2 isthmus, demonstrating a risk of vertebral artery injury for C1-C2 transarticular screw placement. These analyses provided us with useful information for identifying anomalies of the vertebral artery, but they could not visualize the artery and its circumferential osseous tissue simultaneously, nor could they analyze the reciprocal anatomy of both tissues.

METHODS

Thirty-one consecutive patients who submitted to surgery at the craniovertebral junction were evaluated before surgery by three-dimensional computed tomography angiography. Eleven of the patients had congenital osseous anomalies at the craniovertebral junction including os odontoideum and ossiculum terminale. Anomalous vertebral arteries at the extraosseous region were visualized by three-dimensional reconstruction images, and the intraosseous deviation of the vertebral artery at the C2 isthmus was evaluated by multiplanar reconstruction images.

RESULTS

Extraosseous and/or intraosseous vertebral artery anomalies were detected in 9 cases. Eight of the 9 cases had osseous anomalies at the craniovertebral junction. Abnormal courses of the vertebral artery at the extraosseous region were detected in 4 cases: 2 had fenestration and 2 had persistent first intersegmental artery. Asymmetry of bilateral vertebral arteries was found in 5 cases: the right was dominant in 3 cases and the left in 2 cases. A high-riding vertebral artery at the C2 isthmus was detected in 5 cases. Based on these findings, we modified our surgical approach and the screw placement; consequently, no vertebral artery injury occurred.

CONCLUSIONS

In patients having osseous anomalies at the craniovertebral junction, the frequency of vertebral artery anomalies at the extraosseous and intraosseous regions is increased. With preoperative three-dimensional computed tomography angiography, we can precisely identify the anomalous vertebral artery and reduce the risk of intraoperative injury to the vertebral artery, in advance.

Visualizing the Dynamics of Cerebral Aneurysms with Four-dimensional Computed Tomographic Angiography

OBJECTIVE

This study was designed to assess cerebral aneurysm hemodynamics with four-dimensional (4-D) computed tomographic (CT) angiography.

METHODS

Multislice computed tomography with a retrospective electrocardiography-gated reconstruction algorithm was used. The motions of the aneurysmal wall, bleb, and dissecting cavity were rendered observable in a 4-D CT movie.

RESULTS

The findings for 30 patients with 34 aneurysms who underwent 4-D CT angiography were analyzed. Twenty-three aneurysms were documented in the anterior circulation region, and the remaining 11 aneurysms were in the posterior circulation. The average aneurysm size was 6.4 mm, and there were five large aneurysms. There were 28 saccular, 4 dissecting, and 2 fusiform aneurysms. 4-D CT movies were obtained successfully in all aneurysms. The aneurysm wall motion of two growing aneurysms exhibited a highly irregular pulsation in the 4-D CT movie. Pulsating blebs were detected in nine (32.1%) of the saccular aneurysms. In two patients with subarachnoid hemorrhage, preoperative 4-D CT angiography revealed dangerous pulsating blebs that were confirmed as the ruptured points during the surgical procedure. Specifically, in the dissecting aneurysms, the 4-D CT movie revealed a pulsating line, which provided accurate and detailed information regarding the dissecting cavity and intimal flap. The dissecting cavity revealed by the 4-D CT movie could not be detected with conventional or three-dimensional digital subtraction angiography. The 4-D CT movie images were highly useful in making anatomic judgments for the endovascular surgery procedure.

CONCLUSION

4-D CT images are valuable in determining aneurysmal wall dynamics. Highly useful information was obtained regarding intracranial aneurysms with 4-D CT angiography compared with other modalities. Further studies will be necessary to elucidate the optimal application of this new technology to both the pathological characteristics and therapeutic amelioration of aneurysmal features such as dome pulsation, blebs, and growing aneurysms.

Imaging the vertebral artery

Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based perspective. Normal anatomy, normal variants and a number of pathological entities such as vertebral atherosclerosis, arterial dissection, arteriovenous fistula, subclavian steal syndrome and vertebrobasilar dolichoectasia are discussed.

Complementary use of computed tomographic angiography in treatment planning for posterior fossa subarachnoid hemorrhage

OBJECTIVE

The goal of this study was to determine whether the complementary use of computed tomographic angiographic (CTA) assessments would provide additional benefits in the evaluation and treatment of ruptured vertebrobasilar artery aneurysms.

METHODS

In the past 4.5 years, 35 patients with an infratentorial dominant pattern of subarachnoid hemorrhage were complementarily examined with CTA scanning, after undergoing one or more three-dimensional rotational projection digital subtraction angiographic (DSA) studies. The results of these studies were interpreted by the treating neurosurgeon and an interventional radiologist, to examine the usefulness of the findings for the detection of aneurysms and to determine the grade of parent artery vascular filling and the optical definition of the aneurysm. This information provided additional benefits for case management.

RESULTS

Thirty-three aneurysms were detected. For 10 patients, no aneurysm was identified in repeated examinations with the two methods. We detected only 16 of the 25 ruptured aneurysms (64%) on the first DSA scans and, even with repeated examinations, 6 aneurysms were not clearly identified with this technique. CTA scanning revealed the ruptured aneurysms in 25 cases and demonstrated increased vascular filling and improved optical definition of the aneurysms, compared with DSA scanning, in 12 cases (48%). The information obtained from the CTA scans allowed the selection of five patients for endovascular treatment and facilitated the surgical procedures in five cases.

CONCLUSION

Complementary CTA examination of the vertebrobasilar complex provides a higher rate of aneurysm detection and improves the optical definition and anatomic projection of these aneurysms, compared with DSA scanning alone. This facilitates therapeutic decision-making (surgical versus endovascular procedures) and allows neurosurgeons to use more restricted surgical exposures.

Normal variation of vertebral artery on CT angiography and its implications for diagnosis of acquired pathology

PURPOSE

CT angiography (CTA) is rapidly becoming a popular tool for the evaluation of cerebrovascular diseases. Noninvasive diagnosis of vertebral artery pathology using CTA relies in part on diminished vertebral artery size or eccentric position relative to the transverse foramen. However, normal variation of the vertebral artery on CT has not been systematically described.

METHOD

Patients younger than 40 years who underwent CTA for reasons other than evaluation of vertebral artery disease were studied. Area measurements of the vertebral artery and the transverse foramen were performed by three radiologists. Variance component analysis was performed.

RESULTS

There is marked variation in the size of the vertebral artery relative to the transverse foramen, with the vertebral artery occupying 8-85% of the foramen. In many patients, marked asymmetry in relative vertebral artery size and position was observed. This asymmetry would often vary markedly from level to level within the same patient.

CONCLUSION

Vertebral artery size and position in the transverse foramina vary markedly in normal young subjects. These normal variations must be considered when evaluating vertebral artery pathology on CT angiograms.