Yoshiko Sagara

Abdominal CT: Comparison of Low-Dose CT With Adaptive Statistical Iterative Reconstruction and Routine-Dose CT With Filtered Back Projection in 53 Patients

OBJECTIVE The purpose of this article is to retrospectively compare radiation dose, noise, and image quality of abdominal low-dose CT reconstructed with adaptive statistical iterative reconstruction (ASIR) and routine-dose CT reconstructed with filtered back projection (FBP). MATERIALS AND METHODS Fifty-three patients (37 men and 16 women; mean age, 60.8 years) underwent contrast-enhanced abdominal low-dose CT with 40% ASIR. All 53 patients had previously undergone contrast-enhanced routine-dose CT with FBP. With the scanning techniques masked, two radiologists independently graded images for sharpness, image noise, diagnostic acceptability, and artifacts. Quantitative measures of radiation dose and image noise were also obtained. All results were compared on the basis of body mass index (BMI). RESULTS The volume CT dose index (CTDI(vol)), dose-length product, and radiation dose for low-dose CT with ASIR were 17 mGy, 860 mGy, and 13 mSv, respectively, compared with 25 mGy, 1,193 mGy, and 18 mSv for routine-dose CT with FBP, representing an approximate overall dose reduction of 33%. Low-dose CT with ASIR had significantly reduced (p < 0.001) quantitative and qualitative assessment of image noise. Image sharpness, however, was significantly reduced for low-dose CT with ASIR (p < 0.001), although diagnostic acceptability and artifact scores were nearly identical to those for routine-dose CT with FBP. The average CTDI(vol) dose reduction was 66% for patients with a BMI of less than 20 and 23% for patients with a BMI of 25 or greater. CONCLUSION Compared with routine-dose CT with FBP, abdominal low-dose CT with ASIR significantly reduces noise, thereby permitting diagnostic abdominal examinations with lower (by 23-66%) radiation doses. Despite reduced image sharpness in average and small patients, low-dose CT with ASIR had diagnostic acceptability comparable to that of routine-dose CT with FBP.

Diagnostic accuracy of magnetic resonance angiography for cerebral aneurysms in correlation with 3D-digital subtraction angiographic images: a study of 133 aneurysms.

Background and Purpose— We investigated the sensitivity of 3D–time-of flight (3D-TOF) magnetic resonance angiography (MRA) in the detection of cerebral aneurysms with the use of 3D digital subtraction angiography as the gold standard. We also evaluated the effects of location and number of aneurysms (and experience of the reader) on the sensitivity. Methods— 3D-TOF MRA was performed in 82 patients with 133 cerebral aneurysms. Each patient underwent rotational angiography. Three-dimensional reconstructed images were obtained from data of the rotational angiography (as the gold standard). A blind study with 4 readers of different experiences was performed to evaluate the diagnostic accuracy of 3D-TOF MRA for cerebral aneurysms. Results— One hundred five (79%) of all 133 aneurysms were detected with MRA by a neuroradiologist, 100 (75%) were detected by an experienced neurosurgeon, 84 (63%) were detected by a general radiologist, and 80 (60%) were detected by a resident neuroradiologist. For each reader, the detectability was lower for small aneurysms (<3 mm in maximum diameter) and/or for those located at the internal carotid artery and anterior cerebral artery. False-positive aneurysms were 29 for the neuroradiologist, 19 for the neurosurgeon, 31 for the general radiologist, and 30 for the resident neuroradiologist; most of the aneurysms were at the internal carotid artery. Causes of the false-positive and false-negative results included complex flow in a tortuous artery and susceptibility artifacts. Conclusions— Although MRA is useful in the diagnosis of cerebral aneurysms, sufficient experience and careful attention are necessary for accurate diagnosis of aneurysms located at the internal carotid and anterior cerebral arteries.

Endovascular recanalization of acute intracranial vertebrobasilar artery occlusion using local fibrinolysis and additional balloon angioplasty

IntroductionVertebrobasilar artery occlusion (VBO) produces high mortality and morbidity due to low recanalization rate utilization in endovascular therapy. The use of percutaneous transluminal angioplasty (PTA) to improve recanalization rate additional to local intra-arterial fibrinolysis (LIF) was investigated in this study. Results obtained following recanalization therapy in acute intracranial VBO are reported.MethodsEighteen consecutive patients with acute VBO underwent LIF with or without PTA, from August 2000 to May 2006. Eight patients were treated using LIF alone, and ten required additional PTA. Rate of recanalization, neurological status before treatment, and clinical outcomes were evaluated.ResultsOf 18 patients, 17 achieved recanalization. One procedure-related complication of subarachnoid hemorrhage occurred. Overall survival rate was 94.4% at discharge. Seven patients achieved good outcomes [modified Rankin scale (mRS) 0–2], and the other 11 had poor outcomes (mRS 3–6). Five of six patients who scored 9–14 on the Glasgow Coma Scale (GCS) before treatment displayed good outcomes, whereas ten of 12 patients who scored 3–8 on the GCS showed poor outcomes. GCS prior to treatment showed a statistically significant correlation to outcomes (p < 0.05). Moreover, the National Institutes of Health Stroke Scale (NIHSS) before treatment correlated well with mRS (correlation coefficient 0.487). No statistical difference between the good and poor outcome groups was observed for the duration of symptoms, age, etiology, and occlusion site.ConclusionsEndovascular recanalization can reduce mortality and morbidity of acute VBO. Good GCS and NIHSS scores prior to treatment can predict the efficacy of endovascular recanalization.

The anterior medullary-anterior pontomesencephalic venous system and its bridging veins communicating to the dural sinuses: normal anatomy and drainage routes from dural arteriovenous fistulas

IntroductionWe evaluated the normal venous anatomy of the anterior medullary/anterior pontomesencephalic venous (AMV/APMV) system and bridging veins connected to the dural sinuses using magnetic resonance (MR) imaging and demonstrated cases of dural arteriovenous fistulas (DAVFs) with bridging venous drainage.Materials and methodsMR images obtained using a 3D gradient echo sequence in 70 patients without lesions affecting the deep or posterior venous channels were reviewed to evaluate the normal anatomy of the AMV/APMV system and bridging veins. MR images and digital subtraction angiography in 80 cases with intracranial or craniocervical junction DAVFs were reviewed to evaluate the bridging venous drainage from DAVFs.ResultsMR images clearly revealed AMV/APMV in 35 cases. Fifteen cases showed a direct connection between AMV and APMV, while 15 cases showed an indirect communication via the transverse pontine vein or the bridging vein. In the five remaining cases, the AMV and APMV end separately to the bridging vein or the transverse pontine vein. Bridging veins were identified in 34 cases, connecting to the cavernous sinus in 33, to the suboccipital cavernous sinus in 11, and the inferior petrosal sinus in five cases. In 80 DAVF cases, seven of 40 cavernous sinus DAVFs, two craniocervical junction DAVFs, and one inferior petrosal sinus DAVF drained via bridging veins to the brain stem.ConclusionThe AMV/APMV and bridging veins showed various anatomies and frequently showed a connection to the cavernous sinus. Knowledge of the venous anatomy is helpful for the diagnosis and intravascular treatment of DAVFs.

Dural Arteriovenous Fistula Involving the Posterior Condylar Canal

SUMMARY: Although dural arteriovenous fistulas (DAVFs) occur in any structure that is covered by the dura mater, DAVFs at the posterior condylar canal have not been reported. We present a DAVF that involves the posterior condylar canal and drains into the posterior condylar vein and the occipital sinus, which was treated by selective transvenous embolization. Knowledge of venous anatomy of the craniocervical junction and careful assessment of the location of the arteriovenous fistula can contribute to successful treatment.

Selective Transvenous Embolization of Dural Arteriovenous Fistulas Involving the Hypoglossal Canal

The hypoglossal canal contains a venous plexus that connects the inferior petrous sinus, condylar vein, jugular vein and paravertebral plexus. The venous plexus is one of the venous drainage routes of the posterior skull base. Only a few cases of dural arteriovenous fistulas (AVFs) involving the hypoglossal canal have been reported. We describe three cases (a 62-year-old female, a 52-year-old male, and an 83-year-old male) of dural AVFs involving the hypoglossal canal. Symptoms were pulse-synchronous bruit in two cases and proptosis/chemosis in one. All dural AVFs were mainly fed by the ipsilateral ascending pharyngeal artery. Two of three dural AVFs involving the hypoglossal canal mainly drained through the anterior condylar confluence into the inferior petrosal sinus retrogradely with antegrade drainage through the lateral condylar vein. The other one drained through the lateral and posterior condylar veins into the suboccipital cavernous sinus. All dural AVFs were completely occluded by selective transvenous embolization without any complications, and the symptoms disappeared within one week in all cases. Dural AVFs involving the hypoglossal canal can be successfully treated by selective transvenous embolization with critical evaluation of venous anatomy in each case.

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.

Maxillary Artery: Functional and Imaging Anatomy for Safe and Effective Transcatheter Treatment

The maxillary artery is a terminal branch of the external carotid artery. Although the main maxillary artery trunk and most of its branches course within the extracranial space and supply the organs and muscles of the head and neck, other surrounding soft tissues, and the oral and rhinosinusal cavities, other branches supply the dura mater and cranial nerve and can anastomose to the internal carotid artery (ICA). Various pathologic conditions of the intracranial, head, and neck regions can involve the branches of the maxillary artery. Many of these diseases can be treated with endovascular approaches; however, there is a potential risk of complications in the brain parenchyma and cranial nerves related to the meningoneuronal arterial supply and anastomoses to the ICA. Therefore, familiarity with the functional and imaging anatomy of the maxillary artery is essential. In the past, conventional angiography has been the standard imaging technique for depicting the maxillary artery anatomy and related pathologic findings. However, recent advances in computed tomographic, magnetic resonance, and rotational angiography have further elucidated the maxillary artery anatomy by means of three-dimensional representations. Understanding the functional and imaging anatomy of the maxillary artery allows safe and successful transcatheter treatment of pathologic conditions in the maxillary artery territories.

Non-bifurcating carotid artery coexisting with transverse sinus dural arteriovenous fistula.

Dear Sir, Non-bifurcating carotid artery is a very rare anatomical variation of the cervical carotid artery, in which the branches of the external carotid artery (ECA) directly arise from the common carotid artery without forming a bifurcation [1, 2]. Here, we describe a case of isolated transverse sinus dural arteriovenous fistula (AVF) associated with non-bifurcating carotid artery. A 71-year-old man presented with chronic aortic dissection at the thoracic aorta enlarging for the previous 6 months. Brain magnetic resonance angiography was performed for preoperative screening for incidental cerebrovascular diseases and revealed a dural AVF with cortical venous drainage at the right transverse sinus. Although he had no symptoms related to the AVF, endovascular treatment was carried out before the aortic surgery owing to the high risk of aggressive symptoms associated with dural AVFs with cortical venous reflux. Common carotid angiography showed the dural AVF fed by branches of the ECA and non-bifurcating carotid artery, in which the branches of the ECA, including the lingular artery, facial artery, internal maxillary artery, occipital artery (OA), and ascending pharyngeal artery (APA) originated separately from the carotid artery (Fig. 1). Selective angiography of the OA clearly showed the AVF drained via cortical veins with the isolated sinus. The branches of the internal maxillary artery, such as the superficial temporal artery and middle meningeal artery, showed their usual configurations and branching patterns. Transvenous embolization was performed through the occluded sinus with both femoral venous approaches. The sinus was packed with coils, and the AVF disappeared. Non-bifurcating carotid artery, which ascends without forming a bifurcation of the internal carotid artery (ICA) and ECA, is a very rare anatomical variation of the cervical carotid artery [1, 2]. Two hypotheses have been proposed for the development of non-bifurcating carotid artery [3-5]. The first is agenesis of the common stem of the ECA with regression failure of the hyoid artery, and the second is segmental agenesis of the ICA. In the human embryo, the cervical carotid arteries develop by complicated processes of regression, and the communication within the vascular network consists of the ventral aorta, dorsal aorta, aortic arches, and intersegmental arteries. The ventral aorta and dorsal aorta communicate via aortic arches. Among them, the first aortic arch (mandibular artery) further regresses, while the second aortic arch (hyoid artery) continues to the stapedial artery, which produces two branches of the middle meningeal artery and internal maxillary artery. The ICA Neuroradiology (2009) 51:697–698 DOI 10.1007/s00234-009-0542-7

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.