Choong Gon Choi

Safety and efficacy of MRI-based thrombolysis in unclear-onset stroke. A preliminary report

Background: Standard selection criteria for thrombolysis typically exclude patients with acute ischemic stroke with unclear onset. Multimodal MRI screening may be able to identify those with a favorable benefit-risk ratio for thrombolysis. We aimed to evaluate the safety and efficacy of MRI-based thrombolysis in unclear-onset stroke (UnCLOS). Methods: We reviewed the thrombolysis database registries from 3 medical centers in Korea. Subjects received thrombolysis with intravenous tissue plasminogen activator (tPA) or combined intravenous tPA and intra-arterial urokinase within 3 h, or intra-arterial urokinase within 6 h from symptom detection. For patients with UnCLOS, MRI-specific eligibility criteria (i.e. positive perfusion-diffusion mismatch and absence of well-developed fluid-attenuated inversion recovery changes of acute diffusion lesions) were applied. Rates of immediate and 5-day recanalization, early neurological improvement and symptomatic intracranial hemorrhage (ICH) within 48 h after treatment and 3-month modified Rankin Scale (mRS) scores were compared between patients with UnCLOS and those with clear-onset stroke (CLOS). Results: 32 patients with UnCLOS and 223 patients with CLOS were included. Baseline characteristics were comparable between the two groups, except that the proportion of MRI screening was higher, and detection-to-door time and door-to-needle time were longer in the UnCLOS group (p < 0.01). Rates of recanalization (immediate, 81.3 vs. 63.1%; delayed, 80.6 vs. 69.1%), early neurological improvement (on day 1, 46.9 vs. 35.9%; on day 7, 50.0 vs. 49.3%), symptomatic ICH (6.3 vs. 5.8%) and 3-month outcome (mRS 0–1, 37.5 vs. 35.0%; mRS 0–2, 50.0 vs. 49.3%) did not differ between the UnCLOS and CLOS groups. Conclusion: These preliminary results suggest that thrombolysis based on MRI criteria may safely be applied to acute stroke patients with unclear onset.

New Concept in Cavernous Sinus Dural Arteriovenous Fistula Correlation With Presenting Symptom and Venous Drainage Patterns

Background and Purpose— An extradurally located cavernous sinus dural arteriovenous fistula (CSDAVF) exhibits different clinical behavior from other dural arteriovenous fistulas (DAVFs) located between 2 dural leaves. The aim of this study is to define angiographic types of CSDAVF associated with presenting symptom (Sx) and venous drainage patterns. Methods— CSDAVFs during a mean of 23-month follow-up period of 58 patients (17 to 73 years, male:female ratio=8:50) were retrospectively analyzed. The 3 types of CSDAF, ie, proliferative (PT), restrictive (RT), and late restrictive (LRT) types, were categorized by the degrees and patterns of prominent arteriovenous shunt as well as venous flow. The status of the venous connection with CS and the presenting Sx patterns classified as orbital (OrbSxP), ocular (OcuSxP), cavernous (CavSxP), and cerebral (CerSxP) were associated with angiographic types as well as symptom onset, age, and gender. Correlations of discrete and categorical variables were statistically analyzed using the &khgr;2 or Fisher exact test. Results— PT (n=23) and RT (n=23) of CSDAVF were more common than LRT (n=12) (P=0.016) in patients with younger than 65 years and were related to OrbSxP (P=0.015) and CavSxP (P=0.038) in contrast to LRT to OcuSxP (P=0.004). Early onset of Sxs was related to the OrbSxP (P=0.08) and CavSxP (P<0.001). CerSxP (5%) was noted in RT or LRT. OrbSxP was related to the superior ophthalmic venous drainage (P=0.026) and CavSxP to the inferior petrosal sinus (P=0.046) and posterior fossa venous drainages (P=0.014). Seven patients revealed chronological progression of CSDAVF from PT to LRT and even to complete healing. Conclusions— CSDAVF presents as 3 distinctive angiographic types and is associated with presenting Sxs and venous drainage patterns.

Endovascular Strategies for Vertebrobasilar Dissecting Aneurysms

BACKGROUND AND PURPOSE: Dissecting vertebrobasilar aneurysms are challenging to treat, and standard treatment modalities remain controversial. We retrospectively evaluated our experience using endovascular techniques to treat these aneurysms. MATERIALS AND METHODS: From February 1997 to December 2007, 42 patients with intradural vertebrobasilar dissecting aneurysms underwent endovascular treatment. Twenty-nine patients had ruptured aneurysms, and 13 patients had unruptured dissecting aneurysms. The endovascular modalities for vertebrobasilar dissecting aneurysms were the following: 1) trapping (n = 30), 2) proximal occlusion (n = 3), 3) stent with coil (n = 6), and 4) stent alone (n = 3). RESULTS: Seventeen of the 29 patients with ruptured vertebrobasilar dissecting aneurysms had successful outcomes without procedural complications following endovascular treatment. Procedure-related complications were the following: 1) rebleeding (n = 3), 2) posterior inferior cerebellar artery (PICA) territory infarction (n = 6), 3) brain stem infarction (n = 2), and 4) thromboembolism-related multiple infarctions (n = 1). Clinical outcomes were favorable in 32 patients (76.1%). There were 3 (7.1%) procedure-related mortalities due to rebleeding, and 1 (2.4%) non-procedure-related mortality due to pneumonia sepsis. All 13 patients with unruptured vertebrobasilar dissecting aneurysms had favorable clinical and radiologic outcomes without procedure-related complications. CONCLUSIONS: Endovascular procedures for treatment of unruptured symptomatic dissecting aneurysms resulted in favorable outcomes. Ruptured vertebrobasilar dissecting aneurysms are associated with a high risk of periprocedural complications. Risks can be managed by using appropriate endovascular techniques according to aneurysm location, configuration, and relationship with the PICA.

Neuroimaging Strategies for Three Types of Horner Syndrome with Emphasis on Anatomic Location

OBJECTIVE The purposes of this study were to review the anatomy of the oculosympathetic pathway, to describe the clinical characteristics of the three types of Horner syndrome, and to illustrate underlying pathologic features with an emphasis on neuroimaging strategies based on three symptom complexes. CONCLUSION Horner syndrome results from interruption of the oculosympathetic pathway and is usually associated with unique clinical features classified into central, preganglionic, and postganglionic types according to the anatomic location of the underlying pathologic process.

CSF flow quantification of the cerebral aqueduct in normal volunteers using phase contrast cine MR imaging.

Objective To evaluate whether the results of cerebrospinal fluid (CSF) flow quantification differ according to the anatomical location of the cerebral aqueduct that is used and the background baseline region that is selected. Materials and Methods The CSF hydrodynamics of eleven healthy volunteers (mean age = 29.6 years) were investigated on a 1.5T MRI system. Velocity maps were acquired perpendicular to the cerebral aqueduct at three different anatomical levels: the inlet, ampulla and pars posterior. The pulse sequence was a prospectively triggered cardiac-gated flow compensated gradient-echo technique. Region-of-interest (ROI) analysis was performed for the CSF hydrodynamics, including the peak systolic velocity and mean flow on the phase images. The selection of the background baseline regions was done based on measurements made in two different areas, namely the anterior midbrain and temporal lobe, for 10 subjects. Results The mean peak systolic velocities showed a tendency to increase from the superior to the inferior aqueduct, irrespective of the background baseline region, with the range being from 3.30 cm/sec to 4.08 cm/sec. However, these differences were not statistically significant. In the case of the mean flow, the highest mean value was observed at the mid-portion of the ampulla (0.03 cm3/sec) in conjunction with the baseline ROI at the anterior midbrain. However, no other differences were observed among the mean flows according to the location of the cerebral aqueduct or the baseline ROI. Conclusion We obtained a set of reference data of the CSF peak velocity and mean flow through the cerebral aqueduct in young healthy volunteers. Although the peak systolic velocity and mean flow of the CSF differed somewhat according to the level of the cerebral aqueduct at which the measurement was made, this difference was not statistically significant.

Multiple Cerebral Microbleeds in Hyperacute Ischemic Stroke: Impact on Prevalence and Severity of Early Hemorrhagic Transformation After Thrombolytic Treatment

OBJECTIVE The purpose of our study was to assess whether cerebral microbleeds are related to early hemorrhagic transformation after thrombolytic therapy for hyperacute ischemic stroke. MATERIALS AND METHODS The cases of 279 patients with suspected ischemic stroke who underwent MRI including T2*-weighted images were retrospectively evaluated. The inclusion criteria were as follows: imaging performed within 6 hr after symptom onset, presence of territorial infarct of anterior circulation, no history of intracerebral hemorrhage, thrombolytic treatment, and available follow-up MR images. Microbleeds were classified according to number as follows: absent (grade 1, 0 bleeds), mild (grade 2, 1-2 bleeds), moderate (grade 3, 3-10 bleeds), and severe (grade 4, > 10 bleeds). The prevalence and severity of early hemorrhagic transformation after thrombolysis were assessed on follow-up images. RESULTS Among 279 patients, 65 patients (37 men, 28 women; mean age, 67 years) met the inclusion criteria. Microbleeds were found in 25 patients. Early hemorrhagic transformation occurred in nine of 40 patients without microbleeds (grade 1) and in eight of 25 patients with microbleeds: two of 12 patients with grade 2, three of eight patients with grade 3, and three of five patients with grade 4 microbleeds. The presence of symptomatic hemorrhage did not correlate with the number of microbleeds. Results of multivariate logistic regression analysis showed that the presence of microbleeds was not associated with hemorrhagic transformation after thrombolytic treatment. CONCLUSION Small and large numbers of microbleeds are not independent risk factors for early hemorrhagic transformation and symptomatic hemorrhage after thrombolytic therapy for hyperacute ischemic stroke. Additional studies with large groups of subjects are needed to confirm our conclusion.

Balo's concentric sclerosis: a clinical case study of brain MRI, biopsy, and proton magnetic resonance spectroscopic findings.

The antemortem diagnosis of Balos concentric sclerosis was made in a 52 year old woman with subacute right hemiparesis on the basis of brain MRI and stereotactic brain biopsy, which showed multiple ring-like lesions of lamellated demyelination alternating with spared white matter. Proton magnetic resonance spectroscopy (1H-MRS) was carried out one and nine months after the onset of illness. The first 1H-MRS showed a decreased N-acetyl aspartate peak, an increased choline peak, presence of large lipid peaks, and high resonance at 1.4 ppm. The second 1H-MRS disclosed changes such as a decrease of lipid signal, a decrease of resonance at 1.4 ppm, and an increase in the myoinositol peak. These findings are similar to those reported for multiple sclerosis. It seems that this is the first report of 1H-MRS findings in Balos concentric sclerosis.

Which Combination of MR Imaging Modalities Is Best for Predicting Recurrent Glioblastoma? Study of Diagnostic Accuracy and Reproducibility

PURPOSE To compare the added value of dynamic contrast material-enhanced ( CE contrast enhanced ) ( DCE dynamic CE ) magnetic resonance (MR) imaging with that of dynamic susceptibility CE contrast enhanced ( DSC dynamic susceptibility CE ) MR imaging with the combination of CE contrast enhanced T1-weighted imaging and diffusion-weighted ( DW diffusion weighted ) imaging for predicting recurrent glioblastoma. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, with the requirement for informed patient consent waived. CE contrast enhanced T1-weighted images, DW diffusion weighted images, DSC dynamic susceptibility CE MR images, and DCE dynamic CE MR images in 169 patients with pathologically or clinicoradiologically diagnosed recurrent glioblastoma (n = 87) or radiation necrosis (n = 82) were retrospectively reviewed. Histogram cutoffs of quantitative parametric values were calculated from DW diffusion weighted images, DSC dynamic susceptibility CE MR images, and DCE dynamic CE MR images. Area under the receiver operating characteristic curve ( Az area under the ROC curve ) and interreader agreement were assessed. RESULTS For predicting recurrent glioblastoma, adding DCE dynamic CE MR imaging to the combination of CE contrast enhanced T1-weighted imaging and DW diffusion weighted imaging significantly improved Az area under the ROC curve from 0.84 to 0.96 for reader 1 and from 0.81 to 0.97 for reader 2, respectively. Adding DSC dynamic susceptibility CE MR imaging also significantly improved Az area under the ROC curve (0.95 for reader 1 and 0.93 for reader 2). However, there was no significant difference in Az between the combination of CE contrast enhanced T1-weighted imaging, DW diffusion weighted imaging, and DSC dynamic susceptibility CE MR imaging and the combination of CE contrast enhanced T1-weighted imaging, DW diffusion weighted imaging, and DCE dynamic CE MR imaging for both readers. The interreader agreement was highest for the combination of CE contrast enhanced T1-weighted imaging, DW diffusion weighted imaging, and DCE dynamic CE MR imaging (κ = 0.78) and lowest for CE contrast enhanced T1-weighted imaging and DW diffusion weighted imaging (κ = 0.65). CONCLUSION Adding perfusion MR imaging to the combination of CE contrast enhanced T1-weighted imaging and DW diffusion weighted imaging significantly improves the prediction of recurrent glioblastoma; however, selection of perfusion MR method does not affect the diagnostic performance.

Acute necrotizing encephalopathy in Korean infants and children: imaging findings and diverse clinical outcome.

Objective The purpose of our study was to describe acute necrotizing encephalopathy in Korean infants and children, and we sought to evaluate the prognostic factors. Materials and Methods Acute necrotizing encephalopathy was diagnosed in 14 Korean infants and children. We retrospectively analyzed the neuroimaging findings including the follow-up changes. The clinical course of the disease was graded, and we evaluated prognostic factors including age, serum level of the aminotransferase, hemorrhage, and localized atrophy of the brain. Results This encephalopathy predominantly affected the bilateral thalami (n=14), pons (n=12), and midbrain (n=10) in a symmetrical pattern. Hemorrhage was observed in eight patients (57%). On the follow-up images (n=12), the brain lesions were reduced in extent for all patients, and generalized atrophy was seen in six patients. Localized tissue loss was observed in five patients and a complete resolution occurred for one patient. All the patients survived and two recovered completely; mild (n=6) to severe (n=6) neurological deficits persisted in the remaining 12 patients. The significant prognostic factors identified in this study were the presence of hemorrhage (p = 0.009) and localized atrophy (p = 0.015). Conclusion Acute necrotizing encephalopathy in Korean patients showed the characteristic patterns of the post-infectious encephalopathy as described in the literature. The high survival rate and the relatively favorable clinical course observed for the present study suggest a more diverse spectrum of disease severity than was previously described. The presence of hemorrhage and localized tissue loss on MR images may suggest a poor prognosis.

Spinal epidural cavernous hemangioma: MR findings.

Purpose Cavernous hemangiomas with a spinal epidural location are very uncommon vascular tumors in contrast to those in the vertebral body. The purpose of this study was to describe the radiologic findings, focusing on the MR studies, of spinal epidural cavernous hemangiomas. Method Five pathologically proven cases of spinal epidural cavernous hemangioma were retrospectively reviewed. MR (n = 5) and CT (n = 1) were evaluated. Results The level was thoracic (n = 4) or lumbosacral (n = 1). The mass was located in the epidural space and showed paravertebral extension in all cases. It showed a lobulated contour in all cases and encircled the spinal cord partially with a larger posterior (n = 3) or anterior (n = 1) component in four cases. In all cases, the mass showed high signal intensity on T2-weighted images and homogeneous, strong enhancement. Adjacent bony erosion (n = 5) and intervertebral neural foraminal widening (n = 4) were common. Conclusion Spinal epidural cavernous hemangioma shows characteristic MR findings of a lobulated contoured epidural mass partially encircling the spinal cord with a larger posterior component in the spinal canal, high signal intensity on T2-wieghted images, and homogeneous, strong enhancement.