Angiographic observations in idiopathic trigeminal neuralgia

Twenty-four patients with idiopathic trigeminal neuralgia were treated by neurovascular decompression surgery. All patients underwent preoperative vertebral angiography. After surgery, the vertebral angiograms of these patients were retrospectively reviewed. In 23 of the 24 patients, the superior cerebellar artery (SCA) and/or the anterior inferior cerebellar artery (AICA) compressed the trigeminal nerve. In the remaining case, no such compression by vessels was observed. On review of the angiograms, most of the compressing arteries, and the sites and numbers of compression points could be identified. Most of the caudal points of the SCAs which did not compress the trigeminal nerve were located higher than the compression points of the SCAs. It was therefore concluded that vertebral angiography is useful in the preoperative evaluation of compressing arteries. Since superimposition of arteries could be avoided, the straight AP projection was the most valuable of the three projections employed.     

Persistent trigeminal artery variants detected by MR angiography

Persistent trigeminal artery (PTA) variants are cerebellar arteries that originate directly from the precavernous portion of the internal carotid artery (ICA). The goal of our study was to determine the incidence and MR angiographic features of PTA variants. Between April 1996 and September 1999, 523 cranial MR angiographies were performed at our institution. Most of the patients examined had or were suspected of having cerebrovascular disease. We retrospectively reviewed these 523 MR angiograms. A 1.5-T scanner was used in all studies, and maximum intensity projection (MIP) images obtained using the three-dimensional time-of-flight (3D TOF) technique were displayed stereoscopically. Four PTA variants were detected on MR angiograms, at a rate of 0.76 %. At least three of the four PTA variants were anterior inferior cerebellar arteries (AICAs), small tortuous arteries arising from the precavernous portions of the ICAs and taking a posterior course. Although the clinical significance is not great, we found a relatively high incidence of PTA variants on MR angiograms. We stress that knowledge and recognition of these anomalous cerebellar arteries are useful and important in the interpretation of cranial MR angiograms. Received: 4 November 1999; Revised: 16 February 2000; Accepted: 16 March 2000     

Combined first-pass perfusion and viability study at MR imaging in patients with non-ST segment-elevation acute coronary syndromes: feasibility study

PURPOSE: To assess the feasibility of combined perfusion and viability testing by using magnetic resonance (MR) imaging in one setting in patients with non-ST segment-elevation acute coronary syndromes. MATERIALS AND METHODS: The data of 13 patients (mean age, 68 years; range, 40-85 years) at high risk for myocardial infarction who underwent MR imaging at 1.5 T were reviewed. Risk factors were increased troponin T levels in seven, reversible ST depression on an electrocardiogram in four, history of myocardial infarction in two, and presence of heart failure in four. Cine imaging of the left ventricle was performed with a true-fast imaging with steady-state precession (FISP) sequence to assess the regional myocardial contraction and ejection fraction. After injection of 0.1 mmol per kilogram of body weight of gadopentetate dimeglumine, first-pass MR images were obtained by using an inversion-recovery true-FISP sequence at rest and during infusion of adenosine (140 microg/kg/min). Resting and stress images were assessed qualitatively for abnormal regional perfusion (hypoenhancement). The myocardium was divided into three radial segments corresponding to the three coronary artery territories. Delayed (after 15 minutes) contrast material-enhanced images were acquired with use of a segmented inversion-recovery fast low-angle shot sequence. Conventional coronary angiograms were compared with the first-pass images. A more than 50% stenosis in diameter in any coronary artery was considered substantial. Mann-Whitney test was used to assess any significant difference between the left ventricular ejection fraction (LVEF) in patients with and those without myocardial infarct. RESULTS: Mean LVEF was 51.5% (range, 30%-77%). First-pass stress perfusion studies depicted 25 segments of hypoenhancement in 11 patients. Comparison of first-pass perfusion defects with findings on coronary angiograms indicated an overall sensitivity of 92% (24 of 26) and specificity of 92% (12 of 13) in detection of substantial coronary artery disease. Infarcts detected from hyperenhancement on delayed contrast-enhanced images were present in eight segments (four were transmural) in five patients. No significant difference was noted in the LVEF between patients with and those without infarct (P =.724). CONCLUSION: Combined stress perfusion and viability MR imaging was feasible in patients with acute coronary syndromes. First-pass MR perfusion defects compare well with the presence of substantial coronary artery stenosis on conventional angiograms.     

颅底血管与三叉神经根位置关系的应用解剖

目的　研究颅底血管与三叉神经根背侧或腹侧的位置关系,为临床诊治三叉神经痛提供解剖学依据。方法　在手术显微镜下解剖经甲醛固定的成人头部标本 25例,对颅底血管与三叉神经根背侧或腹侧的位置关系进行观测。结果　 (1 )行经三叉神经根背侧并对其产生压迫的颅底血管主要有小脑上动脉 (SCA)占 4. 0%;小脑前下动脉 (AICA)占 2. 0%;基底动脉脑桥支占 2. 0%;岩静脉占 4. 0%;岩静脉及SCA占 2. 0%;岩静脉及AICA占 2. 0%。 (2 )行经三叉神经根腹侧并对其产生压迫的颅底血管主要有SCA占 4. 0%;AICA占 4. 0%。结论　SCA,AICA可在三叉神经根背侧或腹侧产生压迫;基底动脉脑桥支、岩静脉、岩静脉及SCA、岩静脉及AICA,仅对三叉神经根背侧产生压迫。     

小脑上动脉解剖变异的DSA研究

目的：研究数字减影血管造影（DSA）下小脑上动脉的解剖变异。方法：回顾分析我院从2007年8月~2008年12月的137份,常规脑血管造影的DSA片。结果：本组病例SCA重复变异发生率右侧为4.4%,左侧为5.8%,双侧重复变异为0.7%。小脑上动脉起源于大脑后动脉发生率右侧为2.2%,左侧为1.5%,双侧为0.7%。小脑上动脉提前分岔发生率右侧为1.5%,双侧为0.7%。结论：DSA了解小脑上动脉的解剖变异对指导脑血管疾病的介入治疗以及神经外科临床具有重要的意义。     

Three-dimensional gadolinium-enhanced MR angiography of vascular complications after liver transplantation

OBJECTIVE: The goal of this study was to evaluate three-dimensional gadolinium-enhanced MR angiography as a tool for examination of liver transplant patients with potential vascular complications. MATERIALS AND METHODS: Thirty-eight consecutive three-dimensional gadolinium-enhanced MR angiograms were obtained in 34 patients. Results were retrospectively reviewed and correlated with conventional angiography in 20 of the 38 cases and sonography in 37 of the 38 cases. MR angiograms were evaluated for technical adequacy, vascular patency, and parenchymal abnormalities, and results were compared with angiography and sonography. Conventional angiography and surgery were used as gold standards when available. RESULTS: Thirty-four (90%) of 38 MR angiograms were technically adequate. Vascular abnormalities were identified in 20 patients, and 19 of these patients subsequently underwent angiography, surgery, or both. There were seven cases of hepatic artery thrombosis; all were detected with MR angiography with no false-positive or false-negative interpretations. Seven patients had moderate to severe hepatic artery stenosis (>50% narrowing as determined by conventional angiography). MR angiography revealed this stenosis in six of the seven patients, with one false-negative and three false-positive interpretations. Portal vein thrombosis was detected in three patients, and portal vein stenosis was detected in two patients. CONCLUSION: Three-dimensional gadolinium-enhanced MR angiography is useful in the examination of liver transplant patients and offers a noninvasive adjunct in patients with difficult or indeterminate sonographic examinations.     

Reduced caliber of the internal carotid artery: a normal finding with ipsilateral absence or hypoplasia of the A1 segment.

PURPOSETo determine whether a relationship exists between normal variations in anatomy of the circle of Willis and the size of the internal carotid arteries (ICA).METHODSMR angiograms and axial MR images of the brains of 104 patients were reviewed. Included were 10 patients with unilateral absence of the A1 segment of the anterior cerebral artery, 10 with hypoplasia of one A1 segment, 28 with asymmetric A1 segments, nine with isolated unilateral fetal origin of the posterior cerebral artery, and 47 with balanced circulation.RESULTSThe mean ICA diameter measurement for the total population was 4.62 +/- 0.68 mm. In patients with absent A1, the mean ipsilateral and contralateral ICA diameters were 3.63 +/- 0.41 mm and 5.25 +/- 0.52 mm, respectively. The mean percentages of the difference between the diameters of the right and left ICA (31% in the group with absent A1 and 21% in the group with hypoplastic A1) varied significantly from the differences in the ICA diameters among the rest of the population. The diameter differences produced by other common variations (unilateral small A1 segment or fetal origin of the posterior cerebral artery) did not differ significantly from those of the 47 patients with balanced intracranial circulation.CONCLUSIONSThere is an association of unilaterally absent or hypoplastic A1 segments of the anterior cerebral artery with ipsilateral decrease in ICA caliber, and this can be seen on MR angiograms.     

Sickle cell disease: continuous arterial spin-labeling perfusion MR imaging in children

Cerebral blood flow (CBF) was measured with continuous arterial spin-labeling perfusion magnetic resonance (MR) imaging in 14 children with sickle cell disease and seven control subjects. Mean CBF values were higher in patients (P <.005) than in control subjects in all cerebral artery territories. Three patients had decreased CBF in right anterior and middle cerebral artery territories compared with CBF on the left, and one patient had a profound decrease in CBF in all three territories in the right hemisphere. Baseline CBF was significantly decreased in territories seen as unaffected on conventional MR images and MR angiograms in four children with sickle cell disease.     

永存三叉动脉的磁共振血管成像诊断(附24例分析)

目的:以大宗病例运用磁共振血管成像(MRA)检测颅内动脉,以期评估其对永存三叉动脉(PPTA)的诊断价值,并对Saltzman分型法进行补充.方法:自2007年6月至2008年9月,于我院行头颅MRA检查者4650人(男性1977人,女性2673人).采用3D-TOF成像法,容积显示图像重建法.根据MRA显示PPTA及原始图像上血管走行,按Saltzman标准分型分为Ⅰ、Ⅱ、Ⅲ型,并根据PPTA止于小脑上动脉、小脑前下动脉、小脑后下动脉,吻合于大脑后动脉,分支状无吻合将Ⅲ型分为a、b、c、d、e五个亚型.结果:检出PPTA24例,患病率为0.52%.Saltzman Ⅰ型16.67%,Sahzman Ⅱ型16.67%,Sahzman Ⅲ型66.66%(Ⅲ a 0%,Ⅲ b 18.75%、Ⅲc0%、Ⅲd 6.25%、Ⅲ e 75%).结论:磁共振血管成像可明确诊断PPTA,亦可根据动脉结构与形态间接评估其血流动力学特征.     

Trigeminal neuralgia: evaluation of neuralgic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography

PURPOSE: To evaluate three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging and MR angiography with multiplanar reconstruction (MPR) for detection of neurovascular compression (NVC) in patients with trigeminal neuralgia and to evaluate the relationship between clinical symptoms related to trigeminal branches and those related to the site of trigeminal nerve compression. MATERIALS AND METHODS: Fifty-four consecutive patients with trigeminal neuralgia were examined at 3D CISS imaging and MR angiography with a 1.5-T MR system. Original transverse and four reformatted images were used for image interpretation. Vascular contact with the trigeminal nerve at the root entry zone (REZ) was determined, and the nature of the involved vessels was identified. The position of the blood vessel compressing the nerve was classified into cranial, caudal, medial, or lateral sites. Statistical analysis was performed with the chi2 test or the Fisher exact test between two groups and with the chi2 test among more than two groups. RESULTS: In 12 of 15 patients who underwent surgery, the artery that was considered a responsible vessel at 3D CISS imaging and MR angiography was confirmed as such. In the other three patients, the vein was the responsible vessel, which was detected only at 3D CISS imaging. Sixteen (89%) of 18 patients with symptoms related to the maxillary division had NVC at the medial site of the REZ, while 16 (76%) of 21 patients with symptoms related to the mandibular division had NVC at the lateral site (P <.001, chi2 test). CONCLUSION: 3D CISS MR imaging with MPR is useful in the detection of NVC in patients with trigeminal neuralgia, compared with MR angiography. A close relationship was found between the region of neuralgic manifestation and the site of trigeminal nerve compression.     

Persistent trigeminal artery associated with trigeminal neuralgia: hypothesis of neurovascular compression

Introduction The aim of this study was to determine the prevalence of persistent trigeminal artery (PTA) associated with trigeminal neuralgia (TN). Methods From January 1998 to January 2004, 288 MRI scans of patients examined for trigeminal deficits were retrospectively evaluated. MRI was performed at 1.5 T. Scan protocols included cerebral TSE T2-weighted imaging, contrast enhanced SE T1-weighted imaging and thin-section 3D T2-weighted imaging of the temporal bones, 3D TOF pre- and postcontrast MR angiography. TN was defined as episodes of intense stabbing, electric shock-like pain in areas of the face supplied by the trigeminal branches. Neurovascular compression (NVC) was assumed to be present if the patient showed clinical features of TN, if there was contact between an artery and the trigeminal nerve on the affected side, and if other pathology had been excluded. The prevalence and confidence intervals were calculated (95% CI of the prevalence was based on the exact binomial distribution). Results Of 288 patients, 136 matched the criteria for TN. In this series a PTA was detected in three patients, which in all patients was on the same side as the TN. The prevalence of a PTA in patients presenting with TN was 2.2% (CI 0.005–0.06). Conclusion Previous studies have shown PTA as an incidental finding in 0.1–0.6% of cerebral angiograms. The prevalence of a PTA in patients with TN was 2.2%. With respect to the clinical significance, a PTA has to be considered in TN and the diagnosis of a PTA can easily be made using MR imaging/angiography.     

Anterior cerebral artery variations detected by MR angiography

Introduction From anatomical and angiographic studies, it is well known that there are several variations of the anterior cerebral artery (ACA). However, ACA variations have rarely been studied by magnetic resonance (MR) angiography. The purpose of this study was to investigate not only the type, location, configuration, and incidence of ACA variations, but also coexisting arterial pathology such as aneurysms detected by cranial MR angiography.Methods We retrospectively reviewed cranial MR angiography images of 891 patients at our institution. All images were obtained with one of two 1.5-T scanners using the three-dimensional time-of-flight technique. Maximum intensity projection (MIP) images in the horizontal rotation view were displayed stereoscopically. We reviewed these horizontal MIP images, inferosuperior MIP images, and source images, and identified variations of the ACA.Results We found 50 instances (5.6%) of unilateral A1 segment aplasia, 27 (3.0%) of three A2 segments, 18 (2.0%) of an unpaired A2 segment, and 11 (1.2%) fenestrations of the A1 and/or A2 segment. Seven anterior communicating artery (ACoA) aneurysms and one ACA territory embolic infarction were found among the 50 patients with unilateral A1 segment aplasia. One ACoA aneurysm and one pericallosal infarction were found in the 27 patients with three A2 segments. Two distal ACA aneurysms were detected among the 18 patients with an unpaired A2 segment. No associated aneurysm was seen at the fenestrations.Conclusion Although the clinical significance of ACA variations is usually minor, an associated aneurysm is found relatively frequently. Thus, recognizing ACA variations during the interpretation of cranial MR angiograms is important.     

Lower extremity: low-dose contrast agent intraarterial MR angiography in patients--initial results

Institutional review board approval and patient consent were obtained. A low-dose injection protocol for intraarterial three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography was derived from femoral flow phantom studies and prospectively evaluated in patients with peripheral arterial occlusive disease (PAOD). All MR angiograms were obtained at 1.5 T with a T1-weighted gradient-echo sequence. MR angiograms of a gadolinium dilution series (0.8-200.0 mmol/L) were acquired in a femoral phantom at different flow rates. Signal-to-noise ratios (SNRs) above the 75% threshold of the measured maximum were considered optimal. The lowest optimal concentration was injected intraarterially in nine patients to obtain 3D MR angiograms of the thigh and calf station. Contrast-to-noise ratios (CNRs) were calculated for four arterial segments. The low optimal concentration of 50 mmol/L (20-mL bolus volume), about 5% of the total permissible dose, showed SNRs larger than the 75% threshold in the phantom study. In patients, this concentration led to high-spatial-resolution angiograms with mean CNRs of 70.0 +/- 14.5 (+/- standard deviation) for the superficial femoral artery and 47.5 +/- 13.4 at the infrapopliteal level. Low-dose contrast agent intraarterial 3D MR angiography showed high arterial enhancement, enabling assessment of lower extremity arteries in patients with PAOD and multiple injections--a crucial precondition for MR-guided endovascular interventions.     

MRI and MR angiography of persistent trigeminal artery

We describe the MRA and MR angiography (MRA) features of persistent trigeminal artery (PTA) found incidentally in eight patients, with special attention to its origin, site and course. The different patterns of posterior communicating arteries were also noted. The PTA were shown on sagittal, coronal and axial MRI and on MRA. In four cases, the PTA arose from the lateral aspect of the intracavernous internal carotid artery, ran caudally, passing round the bottom of the dorsum sellae to join the basilar artery. In the other four cases, it arose from the medial aspect, ran caudally through the sella turcica and pierced the dorsum sellae to join the basilar artery. The posterior communicating arteries were present unilaterally in five cases and bilaterally in one, and absent bilaterally in two. Identification of a PTA with a trans-sellar course is crucial if a trans-sphenoidal surgery is planned. Received: 20 September 1995 Accepted: 20 January 1996     

Middle cerebral artery variations: duplicated and accessory arteries.

PURPOSEOur goal was to analyze the anatomic similarity between the duplicated middle cerebral artery (MCA) and the accessory MCA and their relationship to the early branches of the MCA.METHODSWe reviewed stereoscopic angiograms of duplicated MCAs in four patients and accessory MCAs in four patients with reference to the origin, size, and cortical supply of these anomalous vessels, along with the presence of perforating arteries and the recurrent artery of Heubner (RAH).RESULTSThe duplicated MCAs supplied the cortical territory of the temporopolar and the anterior temporal and/or middle temporal arteries. The accessory MCAs supplied the cortical territory of the orbitofrontal and/or prefrontal arteries. The duplicated MCAs had perforating arteries in three of four cases and coexisted with the RAH in three of four cases, whereas the main MCA had perforating arteries in all four cases. The accessory MCA had perforating arteries in all four cases and coexisted with the RAH in three of four cases, whereas the main MCA had perforating arteries in one of four cases.CONCLUSIONA consistent cortical supply by the duplicated MCA and the accessory MCA to the anterior temporal lobe and the anterior frontal lobe, respectively, and its similarity to the cortical supply by the early branches of the MCA suggest that development of duplicated and/or accessory MCAs is an anomalously early ramification of the early branches of the MCA.     

Renal arteries: optimization of three-dimensional gadolinium-enhanced MR angiography with bolus-timing-independent fast multiphase acquisition in a single breath hold.

PURPOSE: To compare two different three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiographic techniques. MATERIALS AND METHODS: In 26 patients suspected of having renal artery stenosis, results with fast multiphase 3D MR angiography were compared to those with standard 3D MR angiography in 37 patients. With both techniques, 31-second breath-hold acquisitions were performed. Multiphase angiography comprised five discrete 6.4-second acquisitions without bolus timing, and standard angiography comprised a single acquisition based on test-bolus timing. Two readers evaluated images obtained with both techniques in terms of image quality, artifacts, and vessel conspicuity. Accuracy of findings on the multiphase 3D MR angiograms for assessment of renal artery stenosis was determined by comparing them to digital subtraction angiograms and surgical findings. RESULTS: In the early arterial phase, multiphase 3D MR angiograms showed no image degradation by venous overlay, whereas standard 3D MR angiograms depicted at least minor overlay in 53 of 83 renal arteries (P < .001). Less parenchymal enhancement in the early arterial phase resulted in a higher vessel conspicuity for the divisions and segmental arteries (P < .001). Both readers detected and correctly graded 18 of 20 stenoses on the multiphase angiograms with almost perfect interobserver agreement (kappa > 0.89). CONCLUSION: Renal multiphase 3D MR angiography is an accurate technique requiring no bolus timing. The performance of early arterial phase imaging leads to improved depiction, particularly of the distal renovascular tree, compared to that with standard single-phase 3D MR angiography.     

Postoperative assessment of extracranial-intracranial bypass by time-resolved 3D contrast-enhanced MR angiography using parallel imaging

PURPOSE: Our goals were to assess image quality of time-resolved contrast-enhanced MR angiography (CE MRA), by using 3D data acquisition along with a parallel imaging technique that can improve temporal resolution and to compare this technique with 3D-time-of-flight (TOF) MRA in the postoperative assessment of extracranial (EC)-intracranial (IC) bypass surgery. METHODS: On a 1.5T imaging system, we performed CE MRA by using a 3D fast field-echo sequence in combination with a parallel imaging technique, to obtain images in the coronal plane centered at the postoperative site. Our patient group comprised 17 patients, including 13 after superficial temporal artery-middle cerebral artery (MCA) anastomosis, 3 after external carotid artery-MCA anastomosis, and one after extracranial vertebral artery-posterior cerebral artery anastomosis. Visualization of the anastomosis and the distal flow on the CE-MRA images was assessed comparatively with that on 3D-TOF MR angiograms obtained at the same time. In 6 patients, we also compared the efficiency of visualization on CE-MRA images with that on conventional angiograms. RESULTS: A temporal resolution of 0.8 s/frame could be achieved with the technique employed. The bypass was better demonstrated postoperatively on CE-MRA images than on 3D-TOF MR angiograms in 13 patients (76%), whereas the 2 methods were equivalent in 4 patients (24%). Good correspondence of results was observed in the 6 patients for whom CE MRA and conventional digital subtraction angiography (DSA) images were compared. CONCLUSION: CE MRA by using the parallel imaging technique can increase image acquisition speed with sufficient image quality. This technique is at least equivalent to 3D-TOF MRA to evaluate the postoperative status of EC-IC bypass.     

Contrast-enhanced 3D MR angiography of the carotid artery: comparison with conventional digital subtraction angiography

BACKGROUND AND PURPOSE: Since 1996, several preliminary studies have shown the usefulness of contrast material-enhanced MR angiography for imaging supraaortic vessels. The aim of this study was to compare the accuracy of contrast-enhanced 3D MR angiography with that of digital subtraction angiography (DSA) in the evaluation of carotid artery stenosis. METHODS: A blinded comparison of first-pass contrast-enhanced MR angiography with conventional DSA was performed in 120 patients (240 arteries). MR angiography was performed with a 1.5-T magnet with gradient overdrive equipment, by using a coronal radiofrequency-spoiled 3D fast low-angle-shot sequence after the intravenous injection of gadodiamide. The guidelines of the North American Symptomatic Carotid Endarterectomy Trial for measuring stenosis of the internal carotid artery were applied on maximum intensity projection (MIP) images and conventional catheter angiograms. RESULTS: Grading of stenoses on MR angiograms agreed with grading of stenoses on DSA images in 89% of arteries. In the severe stenosis group (70-99%), agreement was 93%. All internal carotid occlusions (n = 28) and seven of nine pseudo-occlusions were accurately detected with contrast-enhanced MR angiography. The correlation between MR angiography and DSA for determination of minimal, moderate, and severe stenoses and occlusion was statistically significant (r = 0.91, P<.001). CONCLUSIONS: This investigation with a large number of patients confirms that contrast-enhanced MR angiography could become a diagnostic alternative to DSA in the treatment of patients with carotid artery disease.     

Assessment of aortoiliac and renal arteries: MR angiography with parallel acquisition versus conventional MR angiography and digital subtraction angiography

PURPOSE: To prospectively compare the image quality, sensitivity, and specificity of three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography accelerated by parallel acquisition (ie, fast MR angiography) with MR angiography not accelerated by parallel acquisition (ie, conventional MR angiography) for assessment of aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: The study was approved by the institutional review board; informed consent was obtained from all patients. Forty consecutive patients (33 men, seven women; mean age, 63 years) suspected of having aortoiliac and renal arterial stenoses and thus examined with DSA underwent both fast (mean imaging time, 17 seconds) and conventional (mean imaging time, 29 seconds) MR angiography. The arterial tree was divided into segments for image analysis. Two readers independently evaluated all MR angiograms for image quality, presence of arterial stenosis, and renal arterial variants. Image quality, sensitivity, and specificity were analyzed on per-patient and per-segment bases for multiple comparisons (with Bonferroni correction) and for dependencies between segments (with patient as the primary sample unit). Interobserver agreement was evaluated by using kappa statistics. RESULTS: Overall, the image quality with fast MR angiography was significantly better (P=.001) than that with conventional MR angiography. At per-segment analysis, the image quality of fast MR angiograms of the distal renal artery tended to be better than that of conventional MR angiograms of these vessels. Differences in sensitivity for the detection of arterial stenosis between the two MR angiography techniques were not significant for either reader. Interobserver agreement in the detection of variant renal artery anatomy was excellent with both conventional and fast MR angiography (kappa=1.00). CONCLUSION: Fast MR angiography and conventional MR angiography do not differ significantly in terms of arterial stenosis grading or renal arterial variant detection.     

Anatomy and frequency of large pontomesencephalic veins on 3D CT angiograms of the circle of Willis

BACKGROUND AND PURPOSE: The pontomesencephalic veins (PMVs), especially the anterior PMV, are sometimes large enough that they could potentially affect the interpretation of CT angiograms of the circle of Willis. We investigated the frequency and anatomy of visible PMVs on 3D CT angiograms. METHODS: CT angiograms of 211 consecutive patients who underwent CT angiography for a variety of clinical indications were evaluated retrospectively. Images evaluated by consensus between two neuroradiologists were maximum intensity projection and volume-rendered 3D CT angaiograms. RESULTS: Visible PMVs were present on 3D CT angiograms in 11 (5.2%) of 211 patients. Eight of 11 patients had a visible anterior PMV behind the basilar artery. In four patients, the venous caliber of the anterior PMV was sufficiently large enough to be potentially confused with arterial structures. In one patient, 3D CT angiography revealed a large anterior PMV (approximately 2.6 mm in diameter) in the interpeduncular cistern, which had been mistaken for subarachnoid hemorrhage on a nonenhanced CT scan. Two patients had interpeduncular veins of the anterior PMV draping over the dome of a basilar tip aneurysm. In only one patient was the anterior PMV visible possibly owing to arteriovenous malformation. One patient had visible lateral mesencephalic veins, and four patients had visible transverse pontine veins. In one case, on certain views, the transverse pontine veins appeared to arise from the basilar artery. CONCLUSION: Because of their small size, PMVs were seen only infrequently on 3D CT angiograms, but neuroradiologists should be familiar with the normal variants of large PMVs to avoid diagnostic and anatomic confusion.