Kengo Ohta

Oral administration of metal chelator ameliorates motor dysfunction after a small hemorrhage near the internal capsule in rat

Cerebral hemorrhage leads to local production of free iron, radicals, cytokines, etc. To investigate whether a decrease of iron‐mediated radical production influences functional recovery after intracerebral hemorrhage (ICH), a modified ICH rat model with a small hemorrhage near the internal capsule (IC) accompanied with relatively severe motor dysfunction was first developed. Then clioquinol (CQ), an iron chelator that reduces hydroxyl radical production, was orally administrated. Injection of different doses of Type IV collagenase (1.4 μl 1–200 U/ml) into the left striatum near the IC in Wistar rats showed that injection of 7.5 U/ml collagenase resulted in a small hemorrhoidal lesion near the IC with relatively severe motor dysfunction (IC model). Retrograde labeling of neurons in the sensory‐motor cortex and axons in the corticospinal tract using Fluoro‐gold (FG) injection into the spinal cord (C3–C4) showed that few labeled neurons in the sensory‐motor cortex were detected in the IC model, FG‐labeled axons disappeared, and FG‐including ED‐1‐positive cells appeared within 24 hr in the IC. Assessments of behavior and histologic analysis after oral administration of CQ in the IC model indicated that oral administration of CQ prevented a decrease of FG‐labeled neurons, and resulted in better motor‐function recovery. CQ inhibited hydrogen peroxide‐induced cell toxicity in oligodendrocytes in vitro, but not in neurons. Our data suggests that CQ ameliorated motor dysfunction after a small hemorrhage near the IC by a mechanism that is related to reduction of chain‐reactive hydroxyl radical production in oligodendrocytes.

Percutaneous fiducial marker placement under CT fluoroscopic guidance for stereotactic body radiotherapy of the lung: an initial experience

The aim of this study is to describe our initial experience with the VISICOIL, which is the first percutaneous fiducial marker approved for stereotactic body radiotherapy in Japan, and to evaluate its technical and clinical efficacy, and safety. Eight patients underwent this procedure under CT fluoroscopic guidance. One patient had two tumors, so the total number of procedures was nine. We evaluated the technical and clinical success rates of the procedure and the frequencies of complications. Technical success was defined as when the fiducial marker could be placed at the target site, and clinical success was defined as when stereotactic body radiotherapy could be performed without the marker dropping out of position. The technical success rate was 78% (7/9). In one of the two failed cases, we aimed to place the marker inside the tumor, but misplaced it beside the tumor. In the other failed case, we successfully placed the marker beside the tumor as planned; however, the marker migrated to near the pleura after the patient stopped holding their breath. None of the markers dropped out of place, so the clinical success rate was 100% (9/9). The complication rates were as follows: pneumothorax: 56% (5/9), pneumothorax necessitating chest tube placement: 44% (4/9), focal intrapulmonary hemorrhaging: 67% (6/9), hemoptysis: 11% (1/9), mild hemothorax 11% (1/9), air embolism 0% (0/9), and death 0% (0/9). In conclusion, this new percutaneous fiducial marker appears to be useful for stereotactic body radiotherapy due to its good stability.

Reperfusion Rates of Pulmonary Arteriovenous Malformations after Coil Embolization: Evaluation with Time-Resolved MR Angiography or Pulmonary Angiography

PURPOSE To assess reperfusion rates after coil embolization for pulmonary arteriovenous malformations (PAVMs) using time-resolved magnetic resonance (MR) angiography or pulmonary angiography. MATERIALS AND METHODS Patients with PAVMs who underwent embolization and met the following inclusion criteria were included: (a) embolization was performed using bare or fibered platinum microcoils or both, (b) the complete cessation of flow was confirmed by digital subtraction angiography, and (c) follow-up examinations were conducted with time-resolved MR angiography or pulmonary angiography. Coil embolization was performed in 16 patients with 24 untreated or reperfused PAVMs. Sac embolization was performed for 12 untreated PAVMs. Feeding artery embolization was performed as primary embolization in each of the 12 reperfused PAVMs. Five PAVMs were treated 2 to 4 times because of reperfusion. The study included 32 coil embolizations. Follow-up images were reviewed, and reperfusion rates were assessed. The relationships between reperfusion and the location of PAVM, size of PAVM (feeding artery and venous sac), coils (number and total length), timing of embolization (primary or repeat embolization), and types of coils used (with or without fibered coils) were examined. RESULTS Reperfusion rates at 3, 6, 12, and 24 months were 8%, 27%, 36%, and 49%, respectively, for the 12 untreated PAVMs (primary embolization) and 50%, 50%, 92%, and 100%, respectively, for the 12 reperfused PAVMs (repeat embolization) (P = .0062). No significant differences were observed in the other parameters measured. CONCLUSIONS When evaluated with time-resolved MR angiography or pulmonary angiography, reperfusion rates after coil embolization for PAVM were considerably high, particularly with repeat embolization.

Feasibility of time-resolved MR angiography for detecting recanalization of pulmonary arteriovenous malformations treated with embolization with platinum coils.

PURPOSE To assess the feasibility of time-resolved magnetic resonance (MR) angiography as a follow-up method after embolization for pulmonary arteriovenous malformations (PAVMs). MATERIALS AND METHODS Evaluation of 28 PAVMs in 10 patients previously treated with embolization with platinum coils was performed. The mean observation period after embolization was 49 months. All patients underwent unenhanced chest computed tomography (CT) and time-resolved MR angiography followed by transcatheter digital subtraction angiography within 5 weeks for a definite diagnosis. Two radiologists reviewed the CT and time-resolved MR angiography findings using a blinded method. On CT, the draining veins of the PAVMs were measured before and after embolization, and shrinkage rates were calculated. On time-resolved MR angiography, recanalization was diagnosed when the draining vein or aneurysmal sac or both were enhanced in the pulmonary arterial phase. Correlations between recanalization, the shrinkage rate of the draining vein, and the diagnostic accuracies of CT and time-resolved MR angiography were assessed and compared with digital subtraction angiography. RESULTS Five lesions could not be measured on CT because of metallic artifacts. The mean shrinkage rates of the draining vein for recanalized and occluded PAVMs were 23% ± 19 (SD) for recanalized PAVMs and 47% ± 21 for occluded PAVMs (P = .001). The sensitivity and specificity were 93% and 53%, respectively, when the shrinkage rate threshold was set to 50%. On time-resolved MR angiography, the sensitivity and specificity were 93% and 100%, respectively, for Reader 1 and 100% and 93%, respectively, for Reader 2. The κ coefficient was 0.86. CONCLUSIONS Time-resolved MR angiography appears to be a feasible method for PAVM follow-up examinations and to provide a more accurate diagnosis of recanalization compared with unenhanced CT.

Triaxial coil embolization using Guglielmi detachable coils with the voltage-dependent coil-detaching technique

Background A triple co-axial (triaxial) system, consisting of a 1.9-Fr non-tapered microcatheter with one marker, a 2.7-Fr microcatheter, and a 4-Fr catheter, has been recently developed, and can be used in coil embolizations using 0.010-inch Guglielmi detachable coils (GDCs) with a voltage-dependent coil-detaching technique. Purpose To describe this new technique and evaluate its technical feasibility and clinical efficacy. Material and Methods Twenty patients underwent this procedure. Diseases were gastrointestinal bleeding in five patients, traumatic bleeding in three patients, and other diseases in 12 patients. The technical success rate, clinical success rate, and complications of this procedure were evaluated. Technical success was defined as the successful delivery and detachment of a GDC, and clinical success was defined as the immediate postembolic complete cessation of blood flow confirmed by digital subtraction angiography. Results A total of 140 GDCs were used and 20 arteries were embolized. The technical success rate was 94% (131/140) and clinical success rate was 95% (19/20). No major complications were reported. Conclusion The triaxial system in coil embolization using a GDC by monitoring the voltage for coil-detaching appeared to be safe and effective.

Triaxial transarterial embolization for lower gastrointestinal bleeding: A retrospective case series

Abstract Objective: Superselective transcatheter arterial embolization (TAE) is important for lower gastrointestinal (GI) bleeding. A new 1.9-Fr. no-taper microcatheter has recently become available and can be inserted into a 2.7-Fr. microcatheter. We assessed the applicability of this new triple co-axial (triaxial) system to TAE for lower GI bleeding. Material and methods: Five patients with lower GI bleeding underwent TAE with the triaxial system. The approach was via the femoral artery with a 4-Fr. sheath in all cases. The 4-Fr. catheter and triaxial system were inserted into the artery in which extravasation had occurred. Coil embolization was performed with 0.010-inch coils. We evaluated technical success rate, clinical success rate and complications. Results: All five cases of bleeding occurred at the ascending colon, and were caused by diverticulosis in four cases, and an injury to the artery during polypectomy in one case. The 1.9-Fr. no-taper microcatheter could be inserted into the site of extravasation, the vasa recta, in all procedures and TAE was performed successfully. The disappearance of extravasation was confirmed in all cases following TAE. No patients exhibited any signs of recurrent bleeding or complication. Conclusion: The triaxial system appears to be effective and useful in superselective TAE for lower GI bleeding.

Time-resolved Magnetic Resonance Angiography for assessment of recanalization after coil embolization of visceral artery aneurysms.

Summary Background: Follow-up imaging after coil embolization of visceral artery aneurysms is important for detecting recanalization. However, CT examination is susceptible to coil artifacts, which sometimes makes it difficult to assess recanalization. We report 2 cases where recanalization was successfully visualized using time-resolved magnetic resonance angiography after coil embolization of visceral artery aneurysms (one case of right internal iliac artery aneurysm and one case of splenic artery aneurysm). Repeat coil embolization was successfully performed. Case Report: Case 1. An 80-year-old male patient with right internal iliac artery (IIA) aneurysm underwent coil embolization. Aneurysm was located at the bifurcation of the right IIA and therefore, after making a femorofemoral bypass, the distal part of the right IIA, aneurysm and the common iliac artery were embolized with a coil. One year later, the size of the aneurysm seemed to have increased on CT. However, the details were not determined because of metal artifacts. Thus, time-resolved MRA was performed and showed minute vascular flow inside the aneurysm. Angiography was subsequently performed and blood flow inside the aneurysm was visualized similar to the findings in time-resolved MRA. Coil embolization was performed once more and vascular flow inside the aneurysm disappeared. Case 2. A 36-year-old male patient with a splenic artery aneurysm underwent coil packing with preservation of splenic artery patency. Four years later, coil compaction was suspected in a CT scan, but CT could not evaluate recanalization because of severe metal artifacts. Angiography was subsequently performed, showing recanalization of the aneurysm as did the time-resolved MRA. Therefore, coil embolization of the aneurysm and splenic artery was performed again. Conclusions: Follow-up imaging after coil embolization of visceral artery aneurysms is important for detecting recanalization. However, it is sometimes difficult to assess recanalization with CT because of artifacts caused by metal. In our cases, recanalization of aneurysms was clearly shown by time-resolved MRA and re-embolization was successfully performed. In conclusion, time-resolved MRA appears to be useful in assessment of recanalization of visceral artery aneurysms after coil embolization.

Triaxial system in re-embolization for recanalization of pulmonary arteriovenous malformations.

Summary Background Recanalization occurs occasionally, following coil embolization of pulmonary arteriovenous malformations (PAVM), and can lead to ischemic stroke; therefore re-embolization is important. A 1.9-Fr. no-taper microcatheter that can be inserted into a 2.7-Fr. microcatheter (named the triaxial system) has recently become available, and contributes to super-selective catheterization for small or tortuous vessels. The aim of this study was to evaluate the usefulness of re-embolization for recanalization of PAVM using the triaxial system. Material/Methods Recanalization was diagnosed in 8 patients with 13 PAVMs between June 2011 and November 2012, and re-embolization was attempted with a conventional microcatheter at first in all 13 PAVMs. However, in three of them it failed with the conventional microcatheter, and then the system was exchanged to the triaxial system. Thus, re-embolization using the triaxial system was performed in 3 PAVMs of 3 female patients, with a median age of 63 years (range, 46–73 years). We assessed technical success, complications, and outcome. Results The disappearance of recanalization was confirmed by angiography in all re-embolization procedures (technical success rate was 100%). Re-embolization was then successfully achieved inside the original coils, and no branch artery of normal lung tissue was embolized. There were no complications related with this procedure. The blood flow of recanalization was decreased in all cases in a follow-up of 27–33 months (median, 31). Conclusions Triaxial system appears to be useful for recanalization of PAVM, especially in difficult cases with a conventional system.

Percutaneous fiducial marker placement prior to stereotactic body radiotherapy for malignant liver tumors: an initial experience

The aim of this study was to describe our initial experience with a gold flexible linear fiducial marker and to evaluate the safety and technical and clinical efficacy of stereotactic body radiotherapy using this marker for malignant liver tumors. Between July 2012 and February 2015, 18 patients underwent percutaneous fiducial marker placement before stereotactic body radiotherapy for malignant liver tumors. We evaluated the technical and clinical success rates of the procedure and the associated complications. Technical success was defined as successful placement of the fiducial marker at the target site, and clinical success was defined as the completion of stereotactic body radiotherapy without the marker dropping out of position. All 18 fiducial markers were placed successfully, so the technical success rate was 100% (18/18). All 18 patients were able to undergo stereotactic body radiotherapy without marker migration. Thus, the clinical success rate was 100% (18/18). Slight pneumothorax occurred as a minor complication in one case. No major complications such as coil migration or bleeding were observed. The examined percutaneous fiducial marker was safely placed in the liver and appeared to be useful for stereotactic body radiotherapy for malignant liver tumors.

The Role of Time-Resolved MRA for Post-treatment Assessment of Pulmonary Arteriovenous Malformations: A Pictorial Essay.

Pulmonary arteriovenous malformation (PAVM) is defined as a direct connection between the branches of a pulmonary artery and a pulmonary vein that do not pass through the alveolar capillaries. The major treatment strategy for PAVM is coil embolotherapy [1, 2]. Because the rates of recanalization of treated PAVMs are relatively high, periodic assessment of the patency of PAVMs is needed [3]. However, standard follow-up methods have not been established. Time-resolved MRA (TR-MRA) is the latest MR technology, and it provides the ability to acquire a consecutive dynamic angiography [4]. It provides highquality dynamic contrast-enhanced images based on a 3-dimensional gradient-recalled echo (3D-GRE) T1weighted sequence while maintaining adequate spatial and temporal resolution by a ‘keyhole method.’ Recently, the usefulness of TR-MRA for follow-up of treated PAVMs has been reported with a high diagnostic ability (sensitivity and specificity[90 %) [5]. This essay describes the principles of the TR-MRA imaging technique and the practical steps in obtaining high-quality angiography of the pulmonary artery that is adequate for the detection of recanalization of PAVM. Case examples are provided that demonstrate the utility of this technique in evaluating the patency of PAVMs treated with embolotherapy with platinum coils in comparison with transcatheter digital subtraction pulmonary angiography.