Araki T

Two-dimensional thick-slice MR digital subtraction angiography for assessment of cerebrovascular occlusive diseases.

Abstract. Although spatial resolution of current MR angiography is excellent, temporal resolution has remained unsatisfactory. We evaluated clinical applicability of 2D thick-slice, contrast-enhanced subtraction MR angiography (2D-MR digital subtraction angiography) with sub-second temporal resolution in cerebrovascular occlusive diseases. Twenty-five patients with cerebrovascular occlusive diseases (8 moyamoya diseases, 10 proximal internal carotid occlusions, and 2 sinus thromboses ) were studied with a 1.5-T MR unit. The MR digital subtraction angiography (MRDSA) was performed per 0.97 s continuously just after a bolus injection of 15 ml of gadolinium chelates up to 40 s in sagittal (covering hemisphere) or coronal planes. Subtraction images were generated at a workstation. We evaluated imaging quality and hemodynamic information of MRDSA in comparison with those of routine MR imaging, non-contrast MR angiography, and X-ray intra-arterial DSA. Major cerebral arteries, all of the venous sinuses, and most tributaries were clearly visualized with 2D MRDSA. Also, pure arterial phases were obtained in all cases. The MRDSA technique demonstrated prolonged circulation in sinus thromboses, distal patent lumen of proximal occlusion, and some collateral circulation. Such hemodynamic information was comparable to that of intra-arterial DSA. Two-dimensional thick-slice MRDSA with high temporal resolution has a unique ability to demonstrate cerebral hemodynamics equivalent to that of intra-arterial DSA and may play an important role for evaluation of cerebrovascular occlusive diseases.

Effect of duration of contrast material injection on peak enhancement times and values of the aorta, main portal vein, and liver at dynamic MDCT with the dose of contrast medium tailored to patient weight

AIM To investigate the effects of contrast material injection duration on peak enhancement times and attenuation values of the aorta, main portal vein, and liver at MDCT when the dose of contrast material is adjusted to patient weight. MATERIAL AND METHODS Seventy-five patients were randomly assigned to one of five groups, with durations of injection of 25, 30, 35, 40, or 45 s. All patients were injected with 2 ml/kg iodine (300 mg/ml). Attenuation values and peak enhancement times for the aorta, main portal vein, and liver were determined. The relationship between patient weight and enhancement times and values, the differences regarding peak enhancement times, and the relationship between injection duration and enhancement values were investigated using Pearson correlation, analysis of variance (ANOVA), and Spearman rank correlation, respectively. RESULTS No significant correlations were seen between patient weight and peak enhancement times or values. Mean peak enhancement times for the aorta, main portal vein, and liver were 9-11 s, 18-22 s, and 30-34 s, respectively (p>0.05). The correlations between injection duration and peak enhancement values were significant and negative. CONCLUSIONS Regardless of patient weight and injection duration, peak enhancement times of aorta, main portal vein and liver were approximately 10, 20, and 30 s, respectively. The enhancement values tended to be higher for shorter injection durations.

Time-resolved two-dimensional thick-slice magnetic resonance digital subtraction angiography in assessing brain tumors

Abstract. The aim of this study was to evaluate clinical applicability of two-dimensional (2D) thick-slice, contrast-enhanced magnetic resonance digital subtraction angiography (MRDSA) with high temporal resolution in diagnosis of brain tumors. Forty-four patients with brain tumors including, 15 meningiomas, 8 gliomas, 6 metastatic tumors, 4 neuromas, and 2 hemangioblastomas, were studied with 2D MRDSA with frame rate approximately 1 s. Images were continuously obtained following the initiation of bolus injection of gadolinium chelates for 40 s and subtraction images were generated in a workstation. We evaluated visualization of normal cranial vessels on MRDSA and compared MRDSA and intra-arterial digital subtraction angiography (IADSA) with regard to hemodynamic information. Large cerebral arteries, all venous sinuses, and most tributaries were clearly visualized. A stain was present in hypervascular tumors including all 15 meningiomas and 2 hemangioblastomas on MRDSA. Presence of a stain demonstrated on MRDSA and that on IADSA coincided in 16 of 20 cases (Spearman rank correlation value was 0.85). The location, shape, and phase of the stain on MRDSA were similar to those on IADSA. Two-dimensional MRDSA with high temporal resolution has a unique ability to demonstrate cerebral hemodynamics, such as IADSA, and can play an important role in assessing brain tumors.

Endovascular treatment of ureteroarterial fistulas with stent-grafts

Ureteroarterial fistula is a rare condition with life-threatening hematuria that should be diagnosed and treated immediately. We reported two patients of ureteroarterial fistula who underwent successful endovascular treatment by stent-grafts. They had undergone pelvic surgery followed by placement of an indwelling ureteral stent for stricture of the ureter before sudden hematuria occurred. Routine contrast-enhanced computed tomography did not reveal extravasation or a pseudo-aneurysm. Angiograms with multiple oblique views demonstrated small pseudoaneurysms of the iliac artery overriding the ipsilateral ureter. The endovascular treatment of ureteroarterial fistula using stent-grafts was successful, and the hematuria disappeared immediately after stent-graft deployment. The hematuria did not recur up to the last follow-up visits of 3 and 19 months, respectively.

Can Balloon-occluded Retrograde Transvenous Obliteration Be Performed for Gastric Varices without Gastrorenal Shunts?

PURPOSE To evaluate the feasibility for balloon-occluded retrograde transvenous obliteration (BRTO) for gastric varices without gastrorenal shunts. MATERIALS AND METHODS Of 76 patients with gastric varices who were referred for treatment by BRTO, 11 did not have gastrorenal shunts. Contrast medium-enhanced computed tomography (CT) was performed in all patients; seven patients also underwent CT during splenic arteriography. BRTO was performed to insert a balloon catheter into the main draining vein and inject 5% ethanolamine oleate into gastric varices under the temporary balloon occlusion. RESULTS The main draining veins were the subphrenic transverse part of the inferior phrenic vein to the inferior vena cava in five patients, the pericardial vein to the left brachiocephalic vein in two, and the paraesophageal vein to the azygos vein in two. In two patients, the main draining vein was unknown. The overall success rate of BRTO in the nine cases with main draining veins was 67%; BRTO was successful in four of the patients in whom the inferior phrenic vein was the main draining vein, one of the patients in whom the pericardial vein was the main draining vein, and one of the patients in whom the paraesophageal vein was the main draining vein. In the other cases in which the inferior phrenic vein or pericardial vein was the main draining vein, BRTO could not be performed because of extravasation. In another patient in whom the paraesophageal vein was the main draining vein, the main draining pathway could not be identified at angiography because of a complicated azygos venous network. CONCLUSIONS It is feasible to use BRTO to treat cases of gastric varices in which the inferior phrenic vein is the main draining vein. Cases in which the main draining pathway is the pericardial vein are less feasibile for BRTO. The use of BRTO in cases in which the paraesophageal vein is the main draining vein is possible but may be difficult because of a complicated venous network.

Balloon-occluded retrograde transvenous obliteration of gastric varices from unconventional systemic veins in the absence of gastrorenal shunts.

Balloon-occluded retrograde transvenous obliteration of gastric varices in the absence of a gastrorenal shunts can still be performed through unconventional venous routes, such as the left inferior phrenic (ascending portion or transverse portion), pericardial, and azygous-hemiazygous veins. This requires detailed knowledge of venous anatomy, impeccable preprocedural imaging for planning, and high-skill set techniques with smaller balloon-occlusion catheters. The technical results appear to be high (67%-83% depending on the access venous system available), but are lower than conventional balloon-occluded retrograde transvenous obliteration via the gastrorenal shunt.

Dyke-Davidoff-Masson Syndrome Demonstrated by Current MR images A Case Report

Current magnetic resonance imaging techniques demonstrated MR findings of Dyke-Davidoff-Masson syndrome in a 44-year-old man. Statistical parametric mapping analysis of the T1-weighted images showed focal atrophy in the basal ganglia. Three-dimensional white matter fibers of corticospinal tracts, corpus callosum and cingulate bundle were demonstrated using diffusion tensor data correlated to the patients clinical conditions.

Unusual Anatomical Variants of the Left Adrenal Vein via the Renal Capsular Vein Preventing Successful Adrenal Vein Sampling

To the Editor, Studies on adrenal vein sampling (AVS) have reported that blood sampling from the left adrenal vein (LAV) can be easier than from the right side in successful AVS [1–3]. However, among 287 patients who underwent AVS in our hospital, we encountered two unusual cases, in which the central vein of the LAV drained into an unusual variant vein, which was suspected to be the left renal capsular vein. As the unusual anatomy could lead to unsuccessful AVS, we report these two cases with a review of previous reports. For this type of study, formal consent is not required. Informed consent was obtained from two patients included in the report. In case 1, a 52-year-old woman with hypertension due to primary aldosteronism underwent AVS. An upward-directed branch from the cranial side of the left renal vein observed on venography was the left inferior phrenic vein (LIPV); the left adrenal gland did not show enhancement. Multidetector computed tomography (CT) during left inferior phrenic venography with IVR-CT system [4] showed the central vein of the LAV draining into the left ovarian vein (Fig. 1A). Reconstruction of three-dimensional CT (3D-CT) of the LAV from enhanced imaging performed before AVS confirmed that the central vein of the LAV joined the left gonadal vein via its course in front of the left kidney (Fig. 1B). The vein was suspected to be the left renal capsular vein because of its position and course. Venography of the LAV demonstrated enhancement of the left adrenal gland parenchyma, and the vein joined another small capsular and intercostal vein. The cortisol level and plasma aldosterone concentration (PAC) sampled from the central vein of the LAV and LIPV on AVS after stimulation by synthetic adrenocorticotropic hormone (ACTH) (tetracosactide acetate: Daiichi Sankyo, Tokyo, Japan) injection are shown in Table 1. In case 2, a 38-year-old woman with hypertension due to primary aldosteronism underwent enhanced CT imaging before AVS to verify the route. The vein was found to connect with a small branch directed toward the renal capsule and directly drained into the left renal vein from the left adrenal gland via its course in front of the left kidney (Fig. 2). Venography of the LAV demonstrated the LIPV through an anastomosis between the LAV and LIPV. The cortisol level and PAC sampled from the central vein of the LAV and LIPV on ACTH-stimulated AVS are shown in Table 1.

Diffusion Tensor Imaging and 3D Tractography of the Cervical Spinal Cord Using the ECG-Gated Line-scan Technique. A Feasibility Study.

Diffusion tensor (DT) magnetic resonance (MR) imaging in addition to conventional MR images provide valuable information on the brain. This study compared line scan DT imaging with and without the ECG-gating technique to estimate clinical usefulness of the line scan diffusion tensor image (LSDTI) with ECG-gating in evaluating spinal cord diseases in vivo. First, five healthy volunteers participated in the comparison study. LSDWI was performed in three to five sagittal sections with a pulsed-field-gradient diffusion preparation pulse employing two different b-values (0 and 700 s/mm2) along six directions. Apparent diffusion coefficient (ADC) maps and fractional anisotropy (FA) were calculated and three-dimensional tract reconstruction and color schemes of the spinal cord were obtained. Image quality and the acquisition time of each LSDTI were compared. Second, LSDTI with ECG-gating was performed in eighteen patients with cervical spinal cord disorders and evaluated by two neuroradiologists. Images with the ECG-gated technique were all superior to those without ECG—gating. Mean extended time for LSDTI with ECG-gating was approximately two minutes. In clinical use, the ADC and FA of spinal cord in patients with cervical spondylotic myelopathy statically changed. Moreover, demonstration of fibers was correlated with clinical symptoms. ECG-gating technique is preferable to LSDTI. The ADC and FA measurements and 3D fiber tracking of LSDTI with ECG-gating are promising methods to estimate cervical spinal cord pathology in clinical use.