Masashi Shimohira

Evaluation of luminal and vessel wall abnormalities in subacute and other stages of intracranial vertebrobasilar artery dissections using the volume isotropic turbo-spin-echo acquisition (VISTA) sequence: a preliminary study.

OBJECTIVE To evaluate the utility of 3D variable refocusing flip-angle volume isotropic turbo-spin-echo acquisition (VISTA) imaging, using a 1.5-T MRI unit, which can minimize flow artifacts, due to its sequence-endogenous flow-void capability, in the diagnosis of intracranial vertebrobasilar artery dissection (VAD). MATERIAL AND METHODS The presence of intimal flaps, intramural hematomas, vessel dilatations and abnormal vessel enhancements were evaluated on T1-weighted VISTA images from 18 VAD patients with 20 dissected arteries (15 subacute and five at other stages). Additional gadolinium-enhanced T1VISTA images were available for 13 patients. The frequency of flow artifacts on T1VISTA imaging in 70 non-dissected arteries in VAD patients and 12 control subjects was also evaluated. Furthermore, in 13 and eight patients, contrast-enhanced three-dimensional (CE3D) imaging with spoiled gradient-recalled (SPGR) acquisition in steady state and electrocardiographically gated black-blood (BB) T1-weighted imaging (T1WI) were evaluated to compare visualization of false lumens. RESULTS Intimal flaps, intramural hematomas and dilatations were identified on T1VISTA images in 65% (13/20), 55% (11/20) and 90% (18/20) of VADs, respectively. Abnormal vessel enhancement was recognized in 100% (15/15) of VADs on contrast-enhanced T1VISTA images. Only four normal arteries showed small, thin, linear artifacts. Compared with CE3D-SPGR imaging, T1VISTA imaging depicted false lumens more conspicuously in seven VADs (P=0.02). T1VISTA also revealed intimal flaps and hematomas as did BB T1WI. CONCLUSION T1VISTA imaging may be useful for diagnosing VAD at subacute stages, as it can reveal vessel wall and lumen abnormalities with a minimum of flow artifacts.

Transcatheter Arterial Embolization for Segmental Arterial Mediolysis

Purpose: To report outcomes of transcatheter arterial embolization for segmental arterial mediolysis (SAM), a vascular disorder characterized by angiographically documented fusiform aneurysms separated by areas of normal appearing vessel in the celiac or mesenteric arteries. Case Reports: Four patients (3 men; median age 70 years, range 57–77) had a presumptive diagnosis of SAM; the possibility of vasculitis was ruled out based on clinical and laboratory findings. Three patients were symptomatic, with aneurysm rupture; the fourth patient was diagnosed incidentally. Coil embolization was used in 3 cases and N-butyl cyanoacrylate in the other. There was no re-rupture. One patient developed a focal dissection of the superior mesenteric artery 9 months after middle colic artery embolization. Another patient died of perforation of the lower gastrointestinal tract 3 months after treatment, but the cause was unknown; mesenteric ischemia from embolization and arteriopathy could not be ruled out. Conclusion: Transcatheter embolization is useful for SAM. However, it is likely that the morphology associated with SAM transforms rapidly, so patients undergoing mesenteric artery embolization should be monitored at short intervals.

Use of the triaxial microcatheter method in super-selective transcatheter arterial chemoembolisation for hepatocellular carcinoma.

OBJECTIVES Transcatheter arterial chemoembolisation (TACE) has been widely used for inoperable hepatocellular carcinoma (HCC). Super-selective TACE is preferable to non-selective therapy, because it maximises the impact of treatment on the tumour while minimising damage to tumour-free liver parenchyma. It is therefore important to advance the catheter tip as close as possible in the feeding artery. There is now a new microcatheter with a 1.9-Fr tip with no taper, which can be inserted into a 2.7-Fr microcatheter. In this study we describe the new technique of using the two microcatheters called the triaxial microcatheter method. METHODS We evaluated 30 TACE procedures to investigate whether or not the catheter tip could be advanced closer to HCC with the triaxial microcatheter method than with previous TACE using a conventional microcatheter. RESULTS With conventional microcatheters, the level of embolisation was a lobar artery in 4 cases, segmental in 8 cases, subsegmental in 15 cases and sub-subsegmental in only 1 case. TACE could not be performed in two cases. When using the triaxial microcatheter method the level of embolisation was subsegmental in 8 cases, including 2 in which the level was the same as that with a conventional microcatheter, sub-subsegmental in 13 cases and more distal in 7 cases. In the two cases in which TACE could not be performed with the conventional microcatheter, it could be performed sufficiently using the new method. As a whole, in 28 of the 30 procedures (93%) we could successfully advance a catheter tip closer than with the previous TACE. CONCLUSION The triaxial microcatheter method appears to be useful.

Usefulness of CT-guided hookwire marking before video-assisted thoracoscopic surgery for small pulmonary lesions.

The aim of this study was to evaluate the technical and clinical efficacy and safety of CT‐guided hookwire marking before video‐assisted thoracoscopic surgery (VATS) for small pulmonary lesions.

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.

Clinical usefulness of the triaxial system in super-selective transcatheter arterial chemoembolization for hepatocellular carcinoma

Background Transcatheter arterial chemoembolization (TACE) has been widely performed for inoperable hepatocellular carcinoma (HCC). Super-selective TACE is preferable to non-selective therapy and it is important to advance the catheter tip as close to the tumor as possible in the feeding artery. A new microcatheter with a 1.9-Fr non-tapered tip has recently become available and this new microcatheter can be inserted into a 2.7-Fr. microcatheter. It is called the triple co-axial (triaxial) system. Purpose To evaluate the clinical usefulness of super-selective TACE for HCC using the triaxial system. Material and Methods We evaluated 63 HCCs that underwent super-selective TACE. Requirements for inclusion in this study were: (a) HCCs 3 cm or less in diameter; (b) TACE performed by a single operator; and (c) no additional treatment in the absence of local progression. All patients were followed for more than 1 year after TACE. The median follow-up period for surviving patients was 20 months (range, 17–31 months). The conventional system was used in 35 HCCs (control group), and the triaxial system was used in 28 (triaxial group). We reviewed angiographies at TACE and follow-up CT, and then evaluated local tumor status in the two groups. Results Local tumor control rates at 3, 6, and 18 months were 64%, 36%, and 29%, respectively, in the triaxial group, and 40%, 14%, and 8.6%, respectively, in the control group (P = 0.0086). There were no major complications in either group. Conclusion The triaxial system appears to be useful for super-selective TACE and may contribute to achieving higher local control rates for HCC.

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.

Hemosuccus Pancreaticus Associated with Segmental Arterial Mediolysis Successfully Treated by Transarterial Embolization

CONTEXT Hemosuccus pancreaticus, a rare cause of intermittent upper gastrointestinal bleeding, is usually caused by the rupture of an aneurysm associated with chronic pancreatitis. Segmental arterial mediolysis is a rare non-arteriosclerotic, non-inflammatory vascular disease characterized by vacuolization and lysis of the arterial smooth muscle cells. Segmental arterial mediolysis often causes intra-abdominal hemorrhage through aneurysm rupture. To our knowledge, hemosuccus pancreaticus associated with segmental arterial mediolysis has not previously been reported. CASE REPORT A 59-year-old man had suffered from recurrent episodes of epigastric pain and melena. Laboratory data showed mild anemia and an elevated serum amylase level. Upper gastrointestinal endoscopy revealed bloody pancreatic juice exuding from the papilla of Vater. There were no findings suggestive of chronic pancreatitis, such as pancreatic calcification, irregularity of the pancreatic duct and atrophy of the pancreas. Contrast-enhanced computed tomography revealed a large fusiform aneurysm of the middle-distal splenic artery, and dissection of the proximal splenic artery and celiac artery. Leakage of contrast medium from the aneurysm into the main pancreatic duct was also evident. Angiography clearly revealed a fusiform aneurysm of the splenic artery. This was managed successfully by transarterial coil embolization and the patient has subsequently shown no recurrence of epigastric pain or melena. CONCLUSION Segmental arterial mediolysis is a very rare cause of hemosuccus pancreaticus not associated with chronic pancreatitis. Transcatheter arterial embolization is useful for treatment of ruptured aneurysm associated with segmental arterial mediolysis.

Triaxial System for Embolization of Type II Endoleak After Endovascular Aneurysm Repair

Purpose To demonstrate the utility of a triaxial catheter system for embolization of type II endoleak after endovascular aneurysm repair. Technique The technique is illustrated in 2 patients with sac enlargement owing to persistent type II endoleak of lumbar artery origin. In both cases, the access to the iliolumbar and lumbar arteries was very long and tortuous. For selective catheterization in this situation, a 4-F catheter is advanced through the access site, and 2.7-F microcatheter is inserted into the iliolumbar artery, followed by a 1.9-F untapered microcatheter. The latter is advanced along with a 0.014-inch microguidewire into the feeding artery. Supported by the 2.7-F microcatheter, the no-taper microcatheter is then navigated through the endoleak to the draining vessel for embolization. Conclusion This simple-to-use triaxial catheter system seems well suited for superselective embolization of type II endoleaks with very long and tortuous access routes. If glue is used and multiple doses are required, access to the feeding artery is not lost if the smaller microcatheter has to be replaced.