Koichiro Takemoto

Characterization of carotid atherosclerosis with black-blood carotid plaque imaging using variable flip-angle 3D turbo spin-echo: Comparison with 2D turbo spin-echo sequences

PURPOSE To compare the diagnostic performance of three-dimensional variable-flip-angle turbo spin-echo and two-dimensional turbo spin-echo sequences in carotid plaque imaging, with histological analysis as the standard of reference. MATERIALS AND METHODS Twenty-two patients scheduled for carotid endarterectomy underwent carotid plaque imaging including axial T1-weighted and T2-weighted two-dimensional turbo spin-echo, and coronal T1-weighted and T2-weighted three-dimensional variable-flip-angle turbo spin-echo sequences. The quality of images was visually graded using a three-point scale. The signal ratio of the arterial lumen to the plaque component, and that of the carotid plaque to the ipsilateral submandibular gland was calculated in each sequence. These ratios between two-dimensional and three-dimensional sequences were compared for each plaque component according to the histological category of the plaque. RESULTS No significant difference was observed among the overall imaging quality scores of the two-dimensional and three-dimensional sequences, although three-dimensional sequences allowed visualization in arbitrary orientations, as well as depiction of small plaque components such as ulcerations and calcifications. The signal ratio of the plaque to the submandibular gland on T1-weighted three-dimensional sequence was significantly higher than that on two-dimensional sequence (p<0.01), whereas no significant difference was found between two T2-weighted sequences. The signal ratios of the plaque to the submandibular gland of histology-defined soft plaque components were significantly higher on T1-weighted three-dimensional sequence than on two-dimensional sequence (p<0.01), whereas no significant differences were observed between two T1-weighted sequences for hard components. CONCLUSIONS Three-dimensional variable-flip-angle turbo spin-echo is a promising tool for the diagnosis of carotid plaques.

Quantitative evaluation using the plaque/muscle ratio index panels predicts plaque type and risk of embolism in patients undergoing carotid artery stenting

OBJECTIVE We sought to use a magnetic resonance (MR) plaque imaging technique to establish the plaque/muscle ratio (PMR) index panel to identify vulnerable plaques in subjects undergoing carotid artery stenting (CAS). METHODS Between 2008 and 2010 we treated 69 patients (71 lesions) by elective carotid endarterectomy (CEA) and 35 patients (36 lesions) by CAS. All patients underwent preoperative MR plaque imaging and the ratio of plaque signal intensity to the sternocleidomastoid muscle was calculated. In the CEA group, we categorized the histopathological findings made on the surgical specimens. In the CAS group, we assessed the post-procedure diffusion-weighted images. RESULTS PMR index panels for each plaque type were created using the cut-off value obtained from the receiver operating characteristic (ROC) curves of each plaque type. The probability of each of the four plaque types on each panel was assessed by Fishers exact test. Multinomial logistic regression analysis of the DWI-positive findings determined significant probability (p=0.042). CONCLUSION The results of this study suggest quantitative evaluation using the PMR index panel has a probability to predict both the plaque type and risk of embolism in patients being considered for treatment with CAS.

Surgical Treatment for Aneurysms in the Cavernous - Petrous Portion of the Internal Carotid Artery

BACKGROUND As direct surgery to treat aneurysms in the cavernous-petrous portion of the ICA is difficult, proximal ligation of the ICA with or without bypass surgery is still the conventional treatment. Some patients have an ECA-ICA collateral pathway distal to the ligation site. This is related to the recanalization of the aneurysm. We describe the treatment strategy of these aneurysms and the surgical pitfalls of the treatment. METHODS We analyzed 30 cases of symptomatic aneurysms in the cavernous-petrous portion of the ICA. In all cases, proximal ligation of the ICA was performed with bypass surgery followed by BTO. RESULTS In 21 patients who could tolerate BTO, we performed a low-flow bypass. In nine patients who could not tolerate BTO, we performed a high-flow bypass. In four patients with ECA-ICA collateral pathways distal to the ligation site, we performed endovascular parent artery occlusion using detachable coils. In four patients without endovascular parent artery occlusion, we experienced recanalization of the aneurysm. CONCLUSION Based on our experience and in view of the late recanalization of aneurysms that have an ECA-ICA collateral pathway, we recommend that intraoperative angiography should be performed to detect the ECA-ICA collateral pathway in proximal ligation of the ICA.

Surgical Treatment of Intracranial VA Dissecting Aneurysm

OBJECT Intracranial VA dissections are reported to cause headache, brain stem infarction, and SAH with an associated high morbidity and mortality. We aimed to clarify both the clinical characteristics and effectual treatment of intracranial VA dissections, and to present a retrospective analysis of our experience in the treatment. MATERIAL AND METHOD Between 1995 and 2007 we experienced 62 VA dissections in our institution. Fourteen of 62 (23%) cases of VA dissections were associated with aneurysm, and received surgical treatment. Five of fourteen cases presented with SAH, 8/14 cases with ischemia, 1/14 cases with headache. RESULTS In the hemorrhagic group, internal trapping of aneurysm (ITA) was successfully performed in four cases. In one case, bypass surgery was followed by ITA, while one case with treatment-related complication was observed. But Glasgow Outcome Scale (GOS) of almost all cases was severe; 2/5 cases showed good recovery (GR), and 3/5 cases had severe disability. In the non-hemorrhagic group, proximal clipping or trapping was performed in 4/9 cases. Bypass surgery followed by proximal clipping or trapping was performed in 2/9 cases, and ITA in 1/9 case. One case showed treatment-related complication. GOS was GR in all cases. CONCLUSION Outcome in the hemorrhagic group was more severe as compared to the non-hemorrhagic group. The surgical strategy should be planned according to the location of the aneurysm and the origin of PICA.

Endovascular reconstruction for a kinked internal carotid artery after carotid endarterectomy

Background: Although different surgical techniques have been reported for repairing kinked stenosis of the internal carotid artery (ICA) after carotid endarterectomy (CEA), there are no reports using endovascular reconstruction. We present the details of a case successfully treated by carotid artery stenting (CAS). Case Description: A 73-year-old female was referred to our department with fugacious amaurosis and transient sensory disturbance in the left upper limb due to moderate stenosis of the right ICA that was treated by CEA 28 days after admission. However, postoperative angiography and carotid Doppler revealed a kinked ICA with a high-flow velocity that was not present intraoperatively. After 3 months, she had suffered transient ischemic attacks that were refractory to medical treatment, so we performed CAS to prevent future events. The kinked ICA was immediately resolved by stenting and there was no restenosis at a follow-up angiogram 19 months later. Conclusions: This case shows that CAS could be a potential therapeutic option for the management of symptomatic kinking stenosis of the ICA after CEA.

Successful sinus restoration for transverse-sigmoid sinus dural arteriovenous fistula complicated by multiple venous sinus occlusions: The usefulness of preoperative computed tomography venography.

Background: Although sinus restoration for transverse-sigmoid sinus (TSS) dural arteriovenous fistula (DAVF) has rarely been reported over the past decade, its advantage and indication still remain unclear. Herein, we discuss the indications and technical aspects of this therapy with a review of the literature. Case Description: A 79-year-old female was referred to our department with generalized convulsion. An angiogram revealed a DAVF at the junction of the right TSS. The right sigmoid and left transverse sinuses were occluded, which resulted in remarkable leptomeningeal venous reflux and cerebral venous congestion. A preoperative computed tomography (CT) venogram precisely revealed the occluded segment of the right sigmoid sinus, which facilitated the sinus restoration with balloon percutaneous transluminal angioplasty and stenting. Conclusion: Sinus restoration is preferable in patients with severe cerebral venous congestion due to multiple sinus occlusions and/or a restricted collateral venous outlet. CT venography is useful for precise evaluation of the length and configuration of the occluded segment, which thus make it possible to evaluate the feasibility of stenting.

Clinical and radiological correlation in patients with vertebrobasilar artery occlusion

Although ischemic stroke in posterior stroke induces approximately one‐fifth of all strokes, basilar artery occlusion (BAO) and bilateral intracranial vertebral artery occlusion (BIVAO) are relatively rare. The present study was carried out to clarify the differences in clinical features between patients with ischemic stroke caused by BAO and BIVAO.