[Brain Arteriovenous Malformations:Indications and Treatment Results of Endovascular Embolization].

Brain arteriovenous malformations(BAVMs)are rare, but have a risk of serious intracranial hemorrhage in young adults. Endovascular treatment(EVT)has an important role in BAVM management with various purposes, including preoperative devascularization, volume reduction before stereotactic radiotherapy, curative embolization, and palliative embolization. In this article, the author reviews recent studies on EVT and relevant studies on BAVM management. Although no definitive evidences of utilizing EVT have been provided because of the various EVT outcomes depending upon various angioarchitectures, treatment goals, strategies, and physician's skills, EVT is certainly useful in selected cases. The role of EVT in BAVM management should be tailored to each patient while weighing the relative risks and benefits.

[Dural Arteriovenous Fistula].

Dural arteriovenous fistulas(dAVFs), which are arteriovenous shunts between the dural/epidural artery and dural vein and/or dural venous sinus, can cause various symptoms, and the risk of aggressive symptoms such as cerebral hemorrhage and venous infarction mainly depends on venous drainage patterns in patients. Patients with dAVFs with cortical venous reflux have a high risk of aggressive symptoms due to cerebral venous congestion or varix rupture, and they often develop brain edema and/or hemorrhage. In some cases, patients with dAVFs may have CT and MRI findings similar to those of patients with brain tumors. Key MRI findings suggesting dAVFs include multiple small flow voids representing cortical venous reflux adjacent to the hemorrhage or edematous lesion on T2WI and dot-like high-signal-intensity patterns of the feeding arteries and draining veins on time-of-flight MR angiography source images. Cerebral angiography should be performed quickly when dAVFs are suspected with careful assessment using CT/MRI to prevent further worsening of symptoms, particularly for lesions involving the brain stem and cerebellum.

Transarterial Embolization of a Parasellar Hypervascular Tumor.

Embolization of hypervascular tumors has been widely performed for over four decades, particularly for preoperative meningioma. Several benefits of preoperative embolization have been reported, including reduced blood loss, surgical time and surgical complications, and improved outcomes. However, the technical details of both embolization and surgical procedures, and lesions widely vary. Thus, the actual benefits of preoperative embolization have not been clarified by prospective randomized studies. Procedure-related complications due to embolization developed in 3%-12% in previous studies. For parasellar lesions, both surgical resection and embolization have a higher risk of complication than for lesions at other locations because of the complicated neurovascular anatomy in the parasellar area. Therefore, close attention should be paid to the detailed vascular anatomy, embolic material, and related information for embolization and resection in individual cases to improve patient outcomes.

Angiographic and Clinical Characteristics of Thoracolumbar Spinal Epidural and Dural Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: The purpose of this study is to compare the angiographic and clinical characteristics of spinal epidural arteriovenous fistulas (SEAVFs) and spinal dural arteriovenous fistulas (SDAVFs) of the thoracolumbar spine. METHODS: A total of 168 cases diagnosed as spinal dural or extradural arteriovenous fistulas of the thoracolumbar spine were collected from 31 centers. Angiography and clinical findings, including symptoms, sex, and history of spinal surgery/trauma, were retrospectively reviewed. Angiographic images were evaluated, with a special interest in spinal levels, feeders, shunt points, a shunted epidural pouch and its location, and drainage pattern, by 6 readers to reach a consensus. RESULTS: The consensus diagnoses by the 6 readers were SDAVFs in 108 cases, SEAVFs in 59 cases, and paravertebral arteriovenous fistulas in 1 case. Twenty-nine of 59 cases (49%) of SEAVFs were incorrectly diagnosed as SDAVFs at the individual centers. The thoracic spine was involved in SDAVFs (87%) more often than SEAVFs (17%). Both types of arteriovenous fistulas were predominant in men (82% and 73%) and frequently showed progressive myelopathy (97% and 92%). A history of spinal injury/surgery was more frequently found in SEAVFs (36%) than in SDAVFs (12%; P=0.001). The shunt points of SDAVFs were medial to the medial interpedicle line in 77%, suggesting that SDAVFs commonly shunt to the bridging vein. All SEAVFs formed an epidural shunted pouch, which was frequently located in the ventral epidural space (88%) and drained into the perimedullary vein (75%), the paravertebral veins (10%), or both (15%). CONCLUSIONS: SDAVFs and SEAVFs showed similar symptoms and male predominance. SDAVFs frequently involve the thoracic spine and shunt into the bridging vein. SEAVFs frequently involve the lumbar spine and form a shunted pouch in the ventral epidural space draining into the perimedullary vein.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture.

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

Balloon-Occluded Retrograde Transvenous Obliteration for Isolated Gastric Varices Draining through Pericardiophrenic Vein without Gastrorenal or Gastrocaval Shunts.

Balloon-occluded retrograde transvenous obliteration (BRTO) is an effective and minimally invasive treatment for isolated gastric varices (GVs) that is usually performed through a gastrorenal shunt (GRS) or gastrocaval shunt (GCS). However, there are some cases in which GVs drain mainly into the left pericardiophrenic vein without an accessible GRS or GCS. This brief report presents four cases of GVs without a GRS/GCS treated by BRTO through the pericardiophrenic vein. BRTO was successfully performed with the use of flexible balloon catheters without any complications in all four patients, and the GVs were completely obliterated.

Estimating the Radiation Dose to the Fetus in Prophylactic Internal Iliac Artery Balloon Occlusion: Three Cases.

Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiation dose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiation dose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiation dose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiation dose as the absorbed dose. We found that the fetal radiation doses ranged from 12.88 to 31.6 mGy. The fetal radiation dose during the prophylactic IIABOs did not exceed 50 mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus.

Unenhanced magnetic resonance angiography with time-spatial labeling inversion pulse for evaluating visceral artery aneurysms after endosaccular packing with detachable coils: preliminary results.

The aim of this brief report is to compare unenhanced magnetic resonance (MR) angiography with time-spatial labeling inversion pulse (Time-SLIP) with conventional digital subtraction angiography (DSA) in assessing degree of saccular visceral artery aneurysm (VAA) occlusion after endosaccular packing with detachable coils. Eight patients with VAAs (five renal and three splenic artery aneurysms) were enrolled in this study. VAA occlusion rates based on Time-SLIP MR angiography were complete occlusion in four patients, neck remnants in three patients, and body filling in one patient. These findings corresponded with the DSA findings.

Anatomic features and retrograde transvenous obliteration of duodenal varices associated with mesocaval collateral pathway.

PURPOSE: To evaluate techniques and efficacy of retrograde transvenous obliteration for the treatment of duodenal varices associated with mesocaval collateral pathway. MATERIALS AND METHODS: Six consecutive cases of large/growing or ruptured duodenal varices treated by retrograde transvenous obliteration were retrospectively reviewed. Selective balloon-occluded retrograde transvenous obliteration (B-RTO) with 5% ethanolamine oleate (EO) was performed in all cases. When EO could not be sufficiently stagnated in the varices, additional/alternative techniques were performed, including coil embolization of afferent vein or intravariceal injection of n-butyl-2-cyanoacrylate (NBCA). Clinical findings, anatomic features of duodenal varices, obliteration techniques, complications, posttherapeutic computed tomography (CT) findings, and follow-up endoscopic findings were investigated. RESULTS: All duodenal varices were located at the second/third junction of the duodenum and were fed by single (n = 1) or multiple (n = 5) pancreaticoduodenal veins. One varix fed by a single afferent vein was successfully treated by simple selective B-RTO technique alone. The other five cases required coil embolization of afferent vein (n = 1) or intravariceal injection of NBCA (n = 4) because sclerosant was not sufficiently stagnated in the varices. CT 1 week after the procedure showed complete occlusion of the varices in all cases. A duodenal ulcer at the variceal site developed in one patient and was successfully treated by medication. Follow-up endoscopy showed disappearance of varices in all cases, and no recurrence was observed during follow-up. CONCLUSIONS: Retrograde transvenous obliteration is an effective technique for the treatment of duodenal varices. However, additional/alternative techniques are required for successful treatment because of the complex anatomic features of duodenal varices.

Endovascular aortic arch reconstruction using in situ stent-graft fenestration in the brachiocephalic artery.

A patient who had previously undergone retrosternal gastric tube reconstruction for esophageal cancer presented with an aortic arch aneurysm. The patient was treated with endovascular stent-graft placement without median sternotomy, followed by revascularization of the brachiocephalic trunk using percutaneous in situ graft fenestration. A 9-month follow-up examination revealed marked regression of the aneurysm with patency of the stent-graft, without any complications. This in situ fenestration technique may extend the limits of thoracic endovascular therapy for patients who are unsuitable for sternotomy or aortic side-clamping.

Partial thrombosis of gastric varices after balloon-occluded retrograde transvenous obliteration: CT findings and endoscopic correlation.

OBJECTIVE: The purpose of our study was to investigate the frequency and outcomes of partial thrombosis of gastric varices after balloon-occluded retrograde transvenous obliteration (BRTO). MATERIALS AND METHODS: We reviewed retrospectively 69 consecutive patients with gastric varices who were followed-up for > 6 months after treatment with BRTO. All patients underwent contrast-enhanced CT and gastroscopy before and after BRTO. Imaging findings of gastric varices with particular attention to afferent veins, degree of thrombosis, and variceal changes were investigated. RESULTS: On the basis of pretherapeutic CT images, gastric varices were classified into two types: simple (< 3 afferent veins) and complex (≥ 3 afferent veins). Initial follow-up CT showed complete thrombosis in 58 patients (84%) and partial thrombosis in 11 (16%). Partial thrombosis was observed more frequently in complex-type varices (25% vs 9%). No regrowth or recurrent varices were observed in completely thrombosed varices. Follow-up endoscopy showed regrowth of gastric varices at 6-24 months after BRTO in five patients; all of these were complex-type and partially thrombosed varices. All five recurrent varices were treated successfully with repeated BRTO. CONCLUSION: Partial thrombosis after BRTO can occur in complex-type gastric varices, which have a higher risk of regrowth. Additional techniques that achieve complete thrombosis are required for long-term efficacy for complex-type gastric varices.

Pancreatic adenocarcinoma versus chronic pancreatitis: differentiation with triple-phase helical CT.

BACKGROUND: Chronic pancreatitis and pancreatic adenocarcinoma often show similar clinical and imaging appearances. This study aims to differentiate chronic pancreatitis from pancreatic adenocarcinoma by defining enhancement patterns in both pathologic conditions during triple-phase helical CT. METHODS: The study included 42 patients with chronic pancreatitis and 85 patients with pancreatic adenocarcinoma. CT images obtained according to protocol A (scan delays, 30, 60, and 150 s; 300 mg I/mL contrast material) or protocol B (scan delays, 40, 70, and 150 s; 370 mg I/mL contrast material) were retrospectively evaluated. RESULTS: Mean contrast enhancement value of normal pancreas peaked in the first phase (early-washout pattern) while that of chronic pancreatitis peaked in the second phase (delayed-washout pattern), and that of pancreatic adenocarcinoma gradually rose (increasing pattern) in both protocols. Diagnostic indices for pancreatic adenocarcinoma were 82.4% and 94.1% for sensitivity, 83% and 83% for specificity, 82.7% and 90.4% for accuracy in protocols A and B, respectively, when differentiation between chronic pancreatitis and pancreatic adenocarcinoma was performed based on time-attenuation curve patterns. CONCLUSION: Our results indicate that time attenuation curves obtained from triple-phase helical CT in protocol B provide useful information in differentiating chronic pancreatitis from pancreatic adenocarcinoma.

Arterial supply to the pancreas; variations and cross-sectional anatomy.

The pancreas has complex arterial supplies. Therefore, special attention should be paid in pancreatic arterial intervention for patients with acute pancreatitis and pancreatic carcinomas. Knowledge of pancreatic arterial anatomy and arterial territory is important not only to perform pancreatic arterial intervention, but to read the pancreatic angiography and cross-sectional image. We reviewed 226 selective abdominal angiography and CT scans during selective arteriography (CTA) of common hepatic artery, superior mesenteric artery, splenic artery, or peripancreatic arteries including posterior superior pancreaticoduodenal artery, anterior superior pancreaticoduodenal artery, inferior pancreaticoduodenal artery, and dorsal pancreatic artery. CTA images were evaluated to clarify the cross-sectional anatomy of the pancreatic arterial territory. Variations of the peripancreatic arteries were also investigated. In this exhibit, schemes and illustrative cases demonstrate pancreatic arterial territory and variations.

Fibrous stroma and vascularity of pancreatic carcinoma: correlation with enhancement patterns on CT.

OBJECTIVE: To demonstrate the contrast-enhancement behavior of pancreatic carcinoma on dynamic contrast-enhanced CT (DCE-CT), and the relationship between the degree of contrast-enhancement and the vascularity (vessel density) and amount of fibrous stroma (fibrosis within the tumor) on pathological specimen. METHODS: The contrast-enhancement values were measured by producing the subtracting images for obtaining largest region of interests to reduce measurement errors and variability. Vascularity was determined by immunostaining of the tissue sections with factor 8 and the fibrous stroma was determined by picrosirius staining. Correlation of the findings of DCE-CT with pathological findings was performed in 21 patients with pancreatic carcinoma. RESULTS: All but one patient exhibited a gradually increasing enhancement, but there was considerably wide range in contrast-enhancement values of tumors. Examination of the overall relationship between vascularity and fibrous stroma with contrast-enhancement behavior showed that tumor with more fibrosis and higher vascularity had a higher contrast effect through all phases of dynamic study. Tumors having liver metastases tended to be less fibrotic than tumors without liver metastases. CONCLUSION: The contrast-enhancement behavior of pancreatic carcinoma may be helpful in estimating vascularity and the extent of tumor fibrosis and possibility of liver metastases.

Double stent technique for the treatment of an internal carotid artery pseudoaneurysm caused by zone III stab injury.

A 77-year-old man was transferred to the hospital with swelling of his neck and oropharynx after a stab injury to his oral cavity with pruning shears. Findings at complete neurologic examination were normal. Contrast-enhanced computed tomography (CT) and angiography revealed a pseudoaneurysm at the pharyngeal portion of the right internal carotid artery. Endovascular treatment was undertaken by using the double bare stent technique. The pseudoaneurysm was completely occluded immediately after the procedure. There were no complications. There were no further symptoms or evidence of recurrence of the aneurysm during the 18-month follow-up period. The double bare stent technique is safe and effective for the treatment of zone III carotid artery stab injuries.

Extrapancreatic neural plexus invasion by carcinomas of the pancreatic head region: evaluation using thin-section helical CT.

PURPOSE: The aim of this study was to determine the computed tomographic (CT) criteria for diagnosing the second portion of the extrapancreatic neural plexus (PLX-II) invasion by carcinoma of the pancreatic head region on thin-section helical CT. MATERIALS AND METHODS: A total of 41 patients with carcinoma of the pancreatic head region (17 in the pancreas, 24 in the lower common bile duct) underwent three-phase helical CT (collimation 5 mm; reconstruction 2.5 mm) before surgery. Two criteria were established for the assessment of the PLX-II running between the superior mesenteric artery (SMA) and the medial margin of the uncinate process: criterion A: assessment of the area around the SMA and inferior pancreaticoduodenal artery; criterion B: assessment of the jejunal trunk. RESULTS: PLX-II invasion was pathologically confirmed in 19 patients with pancreatobiliary carcinoma. For criterion A, all 19 patients with positive PLX-II invasion and 20 of the 22 with negative PLX-II invasion were correctly diagnosed (sensitivity 100%; specificity 91%; accuracy 95%). For criterion B, 3 of the 17 patients with positive PLX-II invasion and all 20 with negative PLX-II invasion were correctly diagnosed (sensitivity 18%; specificity 100%; accuracy 62%). The two false-positive cases using criterion A were correctly diagnosed using criterion B. CONCLUSION: Thin-section helical CT provides sufficient diagnostic ability regarding PLX-II invasion by carcinoma of the pancreatic head region.

Radiological features of adenoid cystic carcinoma of the uterine cervix.

Adenoid cystic carcinoma (ACC) of the uterine cervix is a rare primary neoplasm of the uterus that occurs in post-menopausal women; its radiological findings have not been described previously. We present the MR findings of a case of ACC. The mass exhibited homogeneous low-signal intensity on T1-weighted images. On T2-weighted images, the mass showed high-signal intensity with a lobulated contour and multiple septum-like internal architectures. It also contained spots of very high-signal intensity, which would represent the mucin in the glandular lumen. The multiple septum-like internal architectures probably represented interglandular fibrous stroma. These MRI findings may be helpful for future diagnoses of ACC of the uterine cervix.

Treatment of intracranial dural arteriovenous fistulas: current strategies based on location and hemodynamics, and alternative techniques of transcatheter embolization.

Intracranial dural arteriovenous fistulas (AVFs) can occur anywhere within the dura mater. Patients may be clinically asymptomatic or may experience symptoms ranging from mild symptoms to fatal hemorrhage, depending on the location (eg, cavernous sinus, transverse-sigmoid sinus, tentorium, superior sagittal sinus, anterior fossa) and venous drainage pattern of the AVF. In the past, dural AVFs have been treated with a variety of approaches, including surgical resection, venous clipping, transcatheter embolization, radiation therapy, or a combination of these treatments. Recent developments in catheter intervention now allow most patients to be cured with transcatheter embolization, although stereotactic radiation therapy is demonstrating good results in an increasing number of cases and surgery is still the preferred option in some cases. Familiarity with drainage patterns, the risk of aggressive symptoms, recent technical advances, and current treatment strategies is essential for the treatment of intracranial dural AVFs.

Turn-back technique with use of a shaped microcatheter for superselective catheterization of arteries originating at acute angles.

The authors have developed a novel "turn-back" technique with use of a shaped microcatheter for superselective catheterization of arteries originating at acute angles. Herein this technique is described in clinical use for superselective catheterization of several arteries including the middle hepatic artery, right gastric artery, right inferior phrenic artery, and tracheal artery in six patients after failed catheterization by conventional techniques as a result of difficult geometry of the arteries. Superselective catheterization and intervention were successfully performed without complication in all cases. This turn-back technique is useful for superselective catheterization of arteries originating at acute angles.

Dispersion of coils after parent-artery occlusion of radiation-induced internal carotid artery pseudoaneurysm.

We report a rare complication following parent-artery occlusion in a patient with radiation-induced carotid pseudoaneurysms. Both the right internal carotid artery pseudoaneurysm and the recurrent external carotid artery pseudoaneurysm were treated by parent-artery occlusion with coils. Although rebleeding was not observed after the second embolization, angiography and endoscopy at the 12-month follow-up showed dispersion and migration of coils into the pharynx and the external auditory canal due to progressive radiation necrosis.