Delayed Rupture of an Anterior Communicating Artery Pseudoaneurysm Caused by Distal Occlusion Thrombectomy Using a Stent Retriever: A Case Report and Mechanism of Injury / 신경중재치료의학

We report a case of delayed rupture of an anterior communicating artery (Acom) pseudoaneurysm following mechanical thrombectomy (MT) of a distal artery occlusion using a stent retriever. An elderly patient with right hemiparesis showed left proximal internal cerebral artery and middle cerebral artery occlusions. During MT, a fragmented thrombus moved to the anterior cerebral artery (ACA). A stent retriever was deployed to the occluded ACA, and the Acom and proximal ACA segment were significantly straightened. Additionally, we attempted a blind exchange mini-pinning (BEMP) technique, but a subarachnoid hemorrhage (SAH) occurred. Bleeding was almost entirely absorbed 9 days after the procedure, but the SAH recurred at 20 days, and computed tomography angiography revealed a new pseudoaneurysm formation in the Acom. We suggest that the proposed mechanism of pseudoaneurysm formation was likely due to the dislocation and avulsion of the Acom perforators when the ipsilateral ACA was pushed and pulled during MT.

Myelin Content in Mild Traumatic Brain Injury Patients with Post-Concussion Syndrome: Quantitative Assessment with a Multidynamic Multiecho Sequence

Objective@#This study aimed to explore the myelin volume change in patients with mild traumatic brain injury (mTBI) with post-concussion syndrome (PCS) using a multidynamic multiecho (MDME) sequence and automatic whole-brain segmentation. @*Materials and Methods@#Forty-one consecutive mTBI patients with PCS and 29 controls, who had undergone MRI including the MDME sequence between October 2016 and April 2018, were included. Myelin volume fraction (MVF) maps were derived from the MDME sequence. After three dimensional T1-based brain segmentation, the average MVF was analyzed at the bilateral cerebral white matter (WM), bilateral cerebral gray matter (GM), corpus callosum, and brainstem. The Mann–Whitney U-test was performed to compare MVF and myelin volume between patients with mTBI and controls. Myelin volume was correlated with neuropsychological test scores using the Spearman rank correlation test. @*Results@#The average MVF at the bilateral cerebral WM was lower in mTBI patients with PCS (median [interquartile range], 25.2% [22.6%–26.4%]) than that in controls (26.8% [25.6%–27.8%]) (p = 0.004). The region-of-interest myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (1.87 cm3 [1.70–2.05 cm3 ] vs. 2.21 cm3 [1.86– 3.46 cm3 ]; p = 0.003) and brainstem (9.98 cm3 [9.45–11.00 cm3 ] vs. 11.05 cm3 [10.10–11.53 cm3 ]; p = 0.015). The total myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (0.45 cm3 [0.39–0.48 cm3 ] vs. 0.48 cm3 [0.45–0.54 cm3 ]; p = 0.004) and brainstem (1.45 cm3 [1.28–1.59 cm3 ] vs. 1.54 cm3 [1.42–1.67 cm3 ]; p = 0.042). No significant correlation was observed between myelin volume parameters and neuropsychological test scores, except for the total myelin volume at the bilateral cerebral WM and verbal learning test (delayed recall) (r = 0.425; p = 0.048). @*Conclusion@#MVF quantified from the MDME sequence was decreased at the bilateral cerebral WM in mTBI patients with PCS. The total myelin volumes at the corpus callosum and brainstem were decreased in mTBI patients with PCS due to atrophic changes.

Multi-Parametric Quantitative MRI for Measuring Myelin Loss in Hyperglycemia-Induced Hemichorea

Hyperglycemia-induced hemichorea (HGHC) is a rare but characteristic hyperkinetic movement disorder involving limbs on one side of the body. In a 75-year-old woman with a left-sided HGHC, conventional brain MR imaging showed very subtle T1-hyperintensity and unique gadolinium enhancement in the basal ganglia contralateral to movements. Multi-parametric MRI was acquired using pulse sequence with quantification of relaxation times and proton density by multi-echo acquisition. Myelin map was reconstructed based on new tissue classification modeling. In this case report of multi-parametric MRI, quantitative measurement of myelin change related to HGHC in brain structures and its possible explanations are presented. This is the first study to demonstrate myelin loss related to hyperglycemic insult in multi-parametric quantitative MR imaging.

Effect of Manganese Content on the Magnetic Susceptibility of Ferrous-Manganese Alloys: Correlation between Microstructure on X-Ray Diffraction and Size of the Low-Intensity Area on MRI

PURPOSE: There is an ongoing search for a stent material that produces a reduced susceptibility artifact. This study evaluated the effect of manganese (Mn) content on the MRI susceptibility artifact of ferrous-manganese (Fe-Mn) alloys, and investigated the correlation between MRI findings and measurements of Fe-Mn microstructure on X-ray diffraction (XRD). MATERIALS AND METHODS: Fe-Mn binary alloys were prepared with Mn contents varying from 10% to 35% by weight (i.e., 10%, 15%, 20%, 25%, 30%, and 35%; designated as Fe-10Mn, Fe-15Mn, Fe-20Mn, Fe-25Mn, Fe-30Mn, and Fe-35Mn, respectively), and their microstructure was evaluated using XRD. Three-dimensional spoiled gradient echo sequences of cylindrical specimens were obtained in parallel and perpendicular to the static magnetic field (B0). In addition, T1-weighted spin echo, T2-weighted fast spin echo, and T2*-weighted gradient echo images were obtained. The size of the low-intensity area on MRI was measured for each of the Fe-Mn binary alloys prepared. RESULTS: Three phases of alpha'-martensite, gamma-austenite, and epsilon-martensite were seen on XRD, and their composition changed from alpha'-martensite to gamma-austenite and/or epsilon-martensite, with increasing Mn content. The Fe-10Mn and Fe-15Mn specimens comprised alpha'-martensite, the Fe-20Mn and Fe-25Mn specimens comprised gamma+epsilon phases, and the Fe-30Mn and Fe-35Mn specimens exhibited a single gamma phase. The size of the low-intensity areas of Fe-Mn on MRI decreased relative to its microstructure on XRD with increasing Mn content. CONCLUSION: Based on these findings, proper conditioning of the Mn content in Fe-Mn alloys will improve its visibility on MR angiography, and a Mn content of more than 25% is recommended to reduce the magnetic susceptibility artifacts on MRI. A reduced artifact of Fe-Mn alloys on MRI is closely related to the paramagnetic constitution of gamma-austenite and/or epsilon-martensite.

A Case of Anterograde Amnesia with Bilateral Hippocampus Involvement After Acute Glufosinate Ammonium Intoxication

A 51-year-old man developed anterograde amnesia following the ingestion of glufosinate ammonium. Brain MRI revealed hyperintense lesions involving the bilateral hippocampus and parahippocampal gyrus, and the right occipital lobe. The mechanism underlying acute glufosinate ammonium intoxication and the differential diagnosis of hippocampal lesions are discussed.

The Effect of Left Subclavian Artery Coverage During Endovascular Repair of the Thoracic Aortic Aneurysm on Cerebral Hemodynamics: Two Cases of Flow Measurement by using 2D Phase Contrast Magnetic Resonance Imaging

The proximity of thoracic aortic aneurysm to the left subclavian artery (LSA) has made the coverage of LSA during thoracic endovascular aortic repair (TEVAR) be essential. Despite controversy concerning the safety of LSA coverage and the indications for LSA revascularizations, the cerebral hemodynamic change after LSA coverage has not been demonstrated. We prospectively examined two patients who would undergo TEVAR with LSA coverage by using 2D cine phase contrast MR imaging. After LSA coverage, the left subclavian steal was properly compensated by the increased flow volumes of both carotid arteries and right vertebral artery, which is the major collateral supply. The total brain supply after TEVAR did not lessen, which showed good correlation with uneventful clinical outcome. Therefore, 2D phase contrast MR imaging can be recommended as a useful technique to evaluate the hemodynamic change of the LSA coverage during TEVAR and to triage the candidate for LSA revascularization.

A newly Developed Hyperintensity Within a Posterior Cerebral Artery Susceptibility Vessel Sign in T2*-Weighted Gradient-Echo Imaging: a Case Report and Correlation with Magnetic Resonance Angiography and Black-Blood Imaging

The susceptibility vessel sign (SVS) on T2*-weighted gradient-echo imaging (T2*-GRE) is useful for detecting intra-arterial clots and monitoring the response to thrombolysis. SVS-GRE was observed in a 52-year-old man with acute occlusion of the posterior cerebral artery (PCA) before and after failed intra-arterial thrombolysis. One-week follow-up T2*-GRE revealed a hyperintensity within the SVS-GRE in the affected PCA. The right PCA remained occluded on time-of-flight (TOF) magnetic resonance angiography (MRA), but its P2 segment exhibited luminal patency on contrast-enhanced (CE) MRA. Black-blood MR imaging using a T1-weighted turbo-spin echo sequence revealed narrowing of the arterial lumen and thickening of the wall due to an atherosclerotic plaque. The observations from TOF-MRA, CE-MRA, and black-blood MR imaging suggest that a newly developed hyperintensity within the SVS-GRE seems to be associated with slow flow through a severe atherosclerotic stenosis or near-occlusion.

Delayed Subarachnoid Hemorrhage from an Embolized Unruptured Intracranial Aneurysm with Minor Recanalization: A Case Report / 신경중재치료의학

Endovascular treatment of cerebral aneurysm is known to be safe and effective in terms of periprocedural complication and rebleeding rates. However, the risk of recanalization in embolized aneurysms necessitates regular follow-ups. We present here a case of subarachnoid hemorrhage from an embolized unruptured aneurysm with stable minor recanalization shown on follow-up images.

Spinal Epidural Arteriovenous Fistula Presented with Subdural Hematoma: a Case of Transarterial Embolization Using NBCA / 신경중재치료의학

We present a patient with spinal epidural arteriovenous fistula presented with subdural hematoma and progressive myelopathy. Transarterial embolization using NBCA results in complete obliteration of fistula without complication. The pathophysiology, angioarchitexture of the lesion and strategy for its cure would be discussed.

Hybrid Two-Dimensional Proton Spectroscopic Imaging of Pediatric Brain: Clinical Application

PURPOSE: To introduce and demonstrate the advantages of the new hybrid two-dimensional (2D) proton spectroscopic imaging (Sl) over the single voxel spectroscopy (SVS) and conventional 2D Sl in the clinical application of spectroscopy for pediatric cerebral disease. MATERIALS AND METHODS: Eighty-one hybrid 2D proton spectroscopic imaging was performed in 79 children (36 normal infants and children, 10 with hypoxic-ischemic injury, 20 with toxic metabolic encephalopathy, seven with brain tumor, three with meningoencephalitis, one with neurofibromatosis, one with Sturge-Weber syndrome and one with lissencephaly) ranging in age from the third day of life to 15 years. In adult volunteers (n = 5), all three techniques including hybrid 2D proton Sl, SVS using PRESS sequence, and conventional 2D proton Sl were performed. Both hybrid 2D proton Sl and SVS using PRESS sequence were performed in clinical cases(n= 12). All measurements were peformed with a 1.5-T scanner using standard head quadrature coil. The 16 x 16 phase encoding steps were set on variable field of view (FOV) depending on the size of the brain. The hybrid volume of interest inside FOV was set as 75 x 75 x 15 mm3 or smaller to get rid of unwanted fat signal. Point-resolved spectroscopy (TR/TE = 1,500 msec/135 or 270 msec) was employed with standard chemical shift selective saturation (CHESS) pulses for water suppression. The acquisition time and spectral quality of hybrid 2D proton Sl were compared with those of SVS and conventional 2D proton Sl. RESULTS: The hybrid 2D proton Sl was successfully conducted upon all patients. The 2D spectral data acquisition time was less than 6 minutes, while the data acquisition time of SVS was 4.3 minutes. This was short enough for pediatric application. The spectra acquired with hybrid 2D proton Sl showed nearly the same sensitivity and spectral resolution with SVS. The spectral quality of hybrid 2D proton Sl was, on the other hand, far better than that of conventional 2D proton Sl. The other advantage of hybrid 2D proton Sl was that the extent of metabolic abnormalities could be evaluated through the characteristics of the relative levels of the three metabolites, i.e., N-acetylaspartate, choline, and creatine. CONCLUSION: The hybrid 2D proton Sl can be successfully employed for the evaluation of the metabolic abnormalities in the various pathologic conditions of pediatric brain without penalty in acquisition time and spectral quality when compared to SVS. The extent of metabolic abnormalities, which cannot be obtained with SVS technique, also can be evaluated with hybrid 2D proton Sl.

(31)P MR Spectroscopic Measurement of Intracellular pH in Normal Human Hearts

PURPOSE: To assess the usefulness of intracellular pH (pHi), calculated by determining the shift of a high-energy metabolite such as inorganic phosphate (Pi) or gamma-ATP after performing MRS with ECG-gated two-dimensional 31P CSI (chemical shift imaging), as a parameter for the overall state of the intracellular milieu. MATERIALS AND METHODS: Proton decoupled 31P CSI was performed on a 1.5-T scanner using a (1)H-(31)P dual-tuned surface coil. Cardiac MRS data were obtained from eight normal volunteers aged 24-32 years with no history of heart disease. From the spectra obtained from several regions of the heart, peak position and peak area were estimated. The metabolic ratios of alpha-, beta-, gamma-ATP, PCr, Pi, phosphodiester and diphosphoglycerate were calculated, and pHi was estimated from the chemical shift of Pi and gamma-ATP resonance. We then compared the data for the anterior myocardium with those previously published. RESULTS: The major phosphorous metabolites identified in these human hearts were as follows: PCr, at -0.1 to +0.1 ppm; three phosphate peaks from ATP, with a chemical shift centered at about -2.7 ppm (gamma-ATP), -7.8 ppm (alpha-ATP), and -16.3 ppm (beta-ATP); and phosphodiester (PDE) at 2-3 ppm, inorganic phosphate (Pi) at 4.5-5.4 ppm, and diphosphoglycerate (DPG) at 5.4-6.3 ppm. The PCr/beta-ATP ratio was 2.20+/-0.17 and the PDE/beta-ATP ratio, 1.04+/-0.09. pHi readings were 7.31+/-0.23 (calculated by the shift of Pi) and 6.81+/-0.20 (calculated by the shift of gamma-ATP). Pi/PCR was 0.539, a ratio higher than that mentioned in previously published reports. CONCLUSION: The measurement of intracelluar metabolism was affected by various kinds of factors. We believe, however, that pHi readings indicate the overall state of the cardiac intracelluar milieu. An unexpected pHi readings, seen at MRS, may reflect errors in the MR procedure itself and, or in the alanytical method.