Three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) and contrast-enhanced MRA of intracranial aneurysms treated with platinum coils

Knowledge framework and emerging trends in intracranial aneurysm magnetic resonance angiography: a scientometric analysis from 2004 to 2020

Background

As magnetic resonance angiography (MRA) has been increasingly used in the follow-up of intracranial aneurysms (IAs) as a non-invasive technique, the knowledge framework and areas of research interest in intracranial aneurysms magnetic resonance angiography (IAMRA) change approximately every 10 years. However, few studies have quantitatively analyzed the published literature in this field. In the present study, we used scientometrics to survey the knowledge field, development trends, and research focus of IAMRA with the aim of providing a reference for further study.

Methods

We collected articles on IAMRA published from 2004 (Jan 1, 2004) to 2020 (May 24, 2020). Web of Science Core Collection databases (WoSCCd) including the Science Citation Index Expanded were searched. An experienced staff member from the Department of Radiology at Southern Medical University, assisted in screening articles for relevant articles. We used ArcGIS (a mapping and location analytics platform) to perform geographic visualization. Excel 2016 was used to analyze the literature data, including number of publications, impact factor (IF), and publication year. CiteSpace V was used to conduct a series of literature feature clustering, including author co-citation analysis, reference co-citation analysis (RCA), and burst keywords analysis.

Results

A total of 1,272 articles on IAMRA published between 2004 and 2020 were included. Of 257 journals, American Journal of Neuroradiology (IF 2018: 3.256) published the most IAMRA articles (109 publications, 8.57%), followed by Journal of Neurosurgery (IF 2018: 4.131, 51 publications, 4.16%), and Neuroradiology (IF 2018: 2.504, 51 publications, 4.01%). Of 56 countries, the USA published the most, with 347 articles [27.28%, IF: 3.14 (average IF of all journals in the country)], followed by Japan (242 articles, 19.03%, IF: 2.38), Germany (135 articles, 10.61%, IF: 3.21), and China (101 articles, 7.94%, IF: 2.86). A total of 1387 institutions published articles, with the Mayo Clinic publishing the most (33 articles, 2.59%), followed by Shanghai Jiao Tong University (25 article, 1.97%), Seoul National University (23 articles, 1.81%), and University Medical Center Utrecht (19 articles, 1.49%). Of 399 authors, Rinkel ranked first with 19 articles, followed by Li MH (18 articles), Uchino A (15 articles), and Saito N (13 articles). Cluster RCA showed that the first cluster was "#0 growth", followed by "#1 Guglielmi detachable coils". Timeline views showed that the time span of "#0 growth" was the closest to today. The modularity value was 0.6971, and the mean silhouette value was 0.5477. According to the burst keyword analysis, "risk factors associated to rupture" was the topic with the strongest burst since 2017. Studies conducted in several countries suggested that age is inversely related to the risk of rupture, which implies the importance of MRA follow-up for patients of different age.

Conclusions

From 2004 to 2020, the number of published IAMRA-related articles gradually increased. The USA and Western Europe lead in the field, with a concentration of cutting-edge talents and high-level scientific research institutions. A synthesis of the clustering results of RCA and burst keyword analysis indicated that unruptured IA growth, stent-assisted coil embolization, and risk factors associated to rupture were the current hotspots in IAMRA research.

MRA versus DSA for the follow-up imaging of intracranial aneurysms treated using endovascular techniques: a meta-analysis

BACKGROUND

Treated aneurysms must be followed over time to ensure durable occlusion, as more than 20% of endovascularly treated aneurysms recur. While digital subtraction angiography (DSA) remains the gold standard, magnetic resonance angiography (MRA) is attractive as a non-invasive follow-up technique. Two different MRA techniques have traditionally been used: time-of-flight (TOF) and contrast-enhanced (CE) MRA. We analysed data from studies comparing MRA techniques with DSA for the follow-up of aneurysms undergoing endovascular treatment. Subgroup analysis of stent-assisted coiling (SAC) and flow diversion (FD) techniques was completed.

METHODS

Comprehensive searches using the Embase, PubMed, and Cochrane databases were performed and updated to November 2018. Pooled sensitivity and specificity were calculated using aneurysm occlusion status as defined by the Raymond-Roy occlusion grading scale.

RESULTS

The literature search yielded 1579 unique titles. Forty-three studies were included. For TOF-MRA, sensitivity and specificity of all aneurysms undergoing endovascular therapy were 88% and 94%, respectively. For CE-MRA, the sensitivity and specificity were 88% and 96%, respectively. For SAC and FD techniques, sensitivity and specificity of TOF-MRA were 86% and 95%, respectively. CE-MRA had sensitivity and specificity of 90% and 92%.

CONCLUSION

MRA is a reliable modality for the follow-up of aneurysms treated using endovascular techniques. While the data are limited, MRA techniques can also be used to reliably follow patients undergoing FD and SAC. However, clinical factors must be used to optimize follow-up regimens for individual patients.

Overview of neuroradiology

Neuroradiology with computed tomography (CT) and magnetic resonance imaging (MRI) is essential for the initial evaluation of patients with a clinical suspicion of brain and spine disorders. Morphologic imaging is required to obtain a probable diagnosis to support the treatment decisions in pre- and perinatal disorders, vascular diseases, traumatic injuries, metabolic disorders, epilepsy, infection/inflammation, neurodegenerative disorders, degenerative spinal disease, and tumors of the central nervous system. Different postprocessing tools are increasingly used for three-dimensional visualization and quantification of lesions. Additional information is provided by angiographic methods and physiologic CT and MRI techniques, such as diffusion MRI, perfusion CT/MRI, MR spectroscopy, functional MRI, tractography, and nuclear medicine imaging methods. Positron emission tomography (PET) is now integrated with CT (PET/CT), and PET/MR scanners have recently also been introduced. These hybrid techniques facilitate the co-registration of lesions with different modalities, and give new possibilites for functional imaging. Repeated imaging is increasingly performed for treatment monitoring. The improved imaging techniques together with the neuropathologic diagnosis after biopsy or surgery allow more personalized treatment of the patient. Neuroradiology also includes endovascular treatment of aneurysms and arteriovenous malformations as well as thrombectomy in acute stroke. This catheter-based treatment has replaced invasive neurosurgery in many cases.

Comparison of 3D TOF MR angiographic accuracy in predicting Raymond grade of flow-diverted versus coiled intracranial aneurysms

The accuracy of 3D time of Flight Magnetic Resonance Angiography (TOF MRA) has been studied extensively for following coiled intracranial aneurysms. It is used by many clinicians for non-invasive follow-up because of its adequate sensitivity in predicting aneurysmal recanalization compared to diagnostic cerebral angiography. The data on the accuracy of 3D TOF MRA for the Pipeline™ Embolization Device (PED) are sparse. In a retrospective chart review, we compared the accuracy of 3D TOF MRA of PED to coil embolization at our institution. 3D TOF MRA had a lower sensitivity and positive predictive value in detecting aneurysmal filling in PED-treated versus coiled aneurysms (57% versus 87% and 80% versus 100%, respectively). Analysis of discrepancies between conventional diagnostic angiography and 3D TOF MRA revealed that 3D TOF MRA was inaccurate in the setting of small residual necks and slow residual filling of the dome with fluid-fluid layers. Therefore, contrasted studies such as contrast-enhanced MRA may be preferred for non-invasively following PED-treated aneurysms to increase accuracy.

A Comparison of Magnetic Resonance Angiography Techniques for the Evaluation of Intracranial Aneurysms Treated With Stent-assisted Coil Embolization

AIM

To identify the effective magnetic resonance angiography (MRA) technique to monitor intracranial aneurysms treated with stent-assisted coiling.

MATERIALS AND METHODS

Retrospective analysis of various MRA techniques was performed in 42 patients. Three neuroradiologists independently compared non-contrast time of flight (ncTOF) MRA of the head, contrast-enhanced time of flight (cTOF) MRA of the head and dynamic contrast-enhanced MRA (CEMRA) of the head and neck or of the head. Digital subtraction angiography (DSA) was available for comparison in 32 cases. Inter-rater agreement (kappa statistic) was assessed.

RESULTS

Artifactual in-stent severe stenosis or flow gap was identified by ncTOF MRA in 23 of 42 cases (55%) and by cTOF MRA in 23 of 38 cases (60%). DSA excluded in-stent stenosis or occlusion in all 32 cases. No difference was noted between ncTOF and cTOF in the demonstration of neck remnants or residual aneurysms in three cases each. CEMRA of the head and neck or of the head was rated superior to ncTOF and cTOF MRA by all three investigators in seven out of eight cases. In one case, all three techniques demonstrated signifcant artifacts due to double stent placement during coiling. The kappa statistic revealed 0.8 agreement between investigators.

CONCLUSIONS

In the assessment of stent-assisted coiling of intracranial aneurysm, both ncTOF and cTOF MRA show similar results. CEMRA tends to show better flow signals in stent and residual aneurysm.

Three-Dimensional Time-of-Flight Magnetic Resonance Angiography Detection of Duplication of the Vertebral Artery in a Large Chinese Population

Background

The aim of this study was to investigate duplication of the vertebral artery (VA) using three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) in a large study population to further our understanding of vascular variations.

Material/Methods

A retrospective analysis of 3D TOF-MRA data in 12 826 cases was performed. The occurrence rate of VA duplication was calculated and accompanied vascular anomalies were recoded.

Results

Twenty-one VA duplication patients were found, with an occurrence rate of 0.164%; 12 of them had left VA duplication with 2 branches initially arising from the aortic arch and left subclavian artery; 9 of them were right VA duplication with the branches originating from the right subclavian artery. In the 21 cases, 11 had other vascular abnormalities.

Conclusions

VA duplication is very rare and often associated with other vascular abnormalities. 3D TOF-MRA can accurately display the duplication variation. Better understanding of the variation is instrumental for disease diagnosis, interventional therapy, and surgical operation.

Follow-up of intracranial aneurysms treated by a WEB flow disrupter: a comparative study of DSA and contrast-enhanced MR angiography

Objective

To compare contrast-enhanced MR angiography (CE-MRA) and DSA for the follow-up of intracranial aneurysms (IAs) treated with the Woven EndoBridge embolization system DL (WEB DL; Sequent Medical, Aliso Viejo, California, USA).

Materials and methods

We retrospectively identified all patients treated with a WEB DL between November 2010 and February 2013 in 2 hospitals. The IA occlusion was graded on follow-up CE-MRA and DSA by 4 independent readers and by 2 readers reaching a consensus, respectively. Interobserver agreement for MRA and intertechnique agreement was evaluated by calculating linear weighted κ.

Results

Fifteen patients with 16 IAs were included. Mean delay between MRA and DSA was 2 months (range 0–16 months). Interobserver agreement for MRA was substantial to almost perfect (κ=0.686–0.921; mean κ=0.809). Intertechnique agreement was moderate to substantial (κ=0.579–0.724; mean κ=0.669). Only three out of five inadequately occluded IAs were detected by MRA.

Conclusions

CE-MRA is a useful tool for the follow-up of IAs treated with a WEB DL. However, early follow-up with DSA remains mandatory to detect inadequately occluded IAs.

Utility of 320-detector row CT for diagnosis and therapeutic strategy for paraclinoid and intracavernous aneurysms

BACKGROUND

The aim of this study was (1) to assess the diagnostic accuracy of 320-detector row computed tomography (CT) for paraclinoid and intracavernous aneurysms, and (2) to investigate whether this method provides sufficient information for surgery.

METHODS

A total of 14 patients with 16 unruptured proximal ICA aneurysms underwent three-dimensional CT angiography (3D-CTA) fusion imaging, which was created by superimposing 3D-CT venography data and/or 3D-bone data onto 3D-CTA data using 320-detector row CT, magnetic resonance imaging (MRI), and 3D digital subtraction angiography (DSA). The images of each modality were assessed using intraoperative findings as the reference standard.

RESULTS

All aneurysms were clearly visualized on 320-detector row CT. Bone subtraction and arterio-venous discrimination were accurate. On 3D-CTA fusion images, 11 aneurysms were diagnosed as "extracavernous" and five as "intracavernous". No discordance in aneurysm location between the 3D-CTA fusion images and the intraoperative findings was found. In contrast, discordance between MRI and intraoperative findings were found in five of the 16 cases (31%), which was significantly more frequent than with 3D-CTA (p = 0.043). The findings DSA, which was performed in nine patients, were also in excellent agreement with the intraoperative findings. However, 3D-CTA fusion imaging provided more comprehensive information, including venous and osseous structures, than 3D-DSA. The 320-detector row CTA after surgery demonstrated a clear relationship between the clip and aneurysmal neck with notably few artifacts, which suggested the utility of this modality for postoperative assessment.

CONCLUSIONS

The 320-detector row CT provided high accuracy for the diagnosis of paraclinoid and intracavernous aneurysms. This technique also provided comprehensive depiction of the aneurysms and surrounding structures. Therefore, this modality might be useful for the diagnosis of the paraclinoid and intracavernous aneurysms and for developing a surgical treatment plan.

MRA versus DSA for follow-up of coiled intracranial aneurysms: a meta-analysis

MR angiography is proposed as a safer and less expensive alternative to the reference standard, DSA, in the follow-up of intracranial aneurysms treated with endovascular coil occlusion. We performed a systematic review and meta-analysis to evaluate the accuracy of TOF-MRA and contrast-enhanced MRA in detecting residual flow in the follow-up of coiled intracranial aneurysms. Literature was reviewed through the PubMed, Cochrane, and EMBASE data bases. In comparison with DSA, the sensitivity of TOF-MRA was 86% (95% CI: 82-89%), with a specificity of 84% (95% CI: 81-88%), for the detection of any recurrent flow. For contrast-enhanced MRA, the sensitivity and specificity were 86% (95% CI: 82-89%) and 89% (95% CI: 85-92%), respectively. Both TOF-MRA and contrast-enhanced MRA are shown to be highly accurate for detection of any recanalization in intracranial aneurysms treated with endovascular coil occlusion.

Time-resolved imaging of contrast kinetics does not improve performance of follow-up MRA of embolized intracranial aneurysms

Background

The use of contrast media and the time-resolved imaging of contrast kinetics (TRICKS) technique have some theoretical advantages over time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment. We prospectively compared the diagnostic performance of TRICKS and TOF-MRA with digital subtracted angiography (DSA) in the assessment of occlusion of embolized aneurysms.

Material/Methods

Seventy-two consecutive patients with 72 aneurysms were examined 3 months after embolization. Test characteristics of TOF-MRA and TRICKS were calculated for the detection of residual flow. The results of quantification of flow were compared with weighted kappa. Intraobserver and interobserver reproducibility was determined.

Results

The sensitivity of TOF-MRA was 85% (95% CI, 65–96%) and of TRICKS, 89% (95% CI, 70–97%). The specificity of both methods was 91% (95% CI, 79–98%). The accuracy of the flow quantification ranged from 0.76 (TOF-MRA) to 0.83 (TRICKS). There was no significant difference between the methods in the area under the ROC curve regarding both the detection and the quantification of flow. Intraobserver reproducibility was very good with both techniques (kappa, 0.86–0.89). The interobserver reproducibility was moderate for TOF-MRA and very good for TRICKS (kappa, 0.74–0.80).

Conclusions

In this study, TOF-MRA and TRICKS presented similar diagnostic performance; therefore, the use of time-resolved contrast-enhanced MRA is not justified in the follow-up of embolized aneurysms.

Follow-up after embolization of ruptured intracranial aneurysms: a prospective comparison of two-dimensional digital subtraction angiography, three-dimensional digital subtraction angiography, and time-of-flight magnetic resonance angiography

INTRODUCTION

To prospectively compare of the diagnostic value of digital subtraction angiography (DSA) and time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment.

METHODS

Seventy-two consecutive patients were examined 3 months after the embolization. The index tests included: two-dimensional DSA (2D-DSA), three-dimensional DSA (3D-DSA), and TOF-MRA. The reference test was a retrospective consensus between 2D-DSA images, 3D-DSA images, and source rotational DSA images. The evaluation included: detection of the residual flow, quantification of the flow, and validity of the decision regarding retreatment. Intraobserver agreement and interobserver agreement were determined.

RESULTS

The sensitivity and specificity of residual flow detection ranged from 84.6 % (2D-DSA and TOF-MRA) to 92.3 % (3D-DSA) and from 91.3 % (TOF-MRA) to 97.8 % (3D-DSA), respectively. The accuracy of occlusion degree evaluation ranged from 0.78 (2D-DSA) to 0.92 (3D-DSA, Cohen's kappa). The 2D-DSA method presented lower performance in the decision on retreatment than 3D-DSA (P < 0.05, ROC analysis). The intraobserver agreement was very good for all techniques (κ = 0.80-0.97). The interobserver agreement was moderate for TOF-MRA and very good for 2D-DSA and 3D-DSA (κ = 0.72-0.94).

CONCLUSION

Considering the invasiveness of DSA and the minor difference in the diagnostic performance between 3D-DSA and TOF-MRA, the latter method should be the first-line modality for follow-up after aneurysm embolization.

Residual Flow After Cerebral Aneurysm Coil Occlusion

Background and Purpose—

The purpose of this study was to estimate the performance measures of MR angiography (MRA) in the diagnosis of aneurysm residual flow after coil occlusion.

Methods—

Patients having at least 1 cerebral aneurysm treated with coil occlusion were prospectively and consecutively enrolled. Time of flight and contrast-enhanced MRA were performed the same day of the DSA follow-up. The degree of aneurysm occlusion and dimensions of the residual flow were evaluated by independent readers at MRA and digital subtraction angiogram. MRA performance measures were estimated in a cross-sectional analysis and repeated in subgroups of aneurysm sizes and locations. MRA predictive values for recurrence were also estimated using a longitudinal design.

Results—

We obtained 167 aneurysm evaluations for each imaging modality. Class 3 residual flow was seen on digital subtraction angiogram follow-up in 27%. The sensitivity and specificity of MRA was 88% (95% CI, 80–94) and 79% (95% CI, 67–88), respectively. The positive predictive value for a Class 3 recurrence was 67% (95% CI, 51–80) and the negative predictive value was 93% (95% CI, 86–97). Time-of-flight MRA underestimated the length of the residual flow ( P =0.039), whereas contrast-enhanced MRA overestimated its width ( P <0.0001). MRA sensitivity for a Class 3 residual flow was lower for aneurysms <6 mm ( P =0.01).

Conclusions—

MRA has sufficient accuracy for screening of aneurysm residual flow after coil occlusion. Due to its lower negative predictive value, recurrent aneurysms should be confirmed with digital subtraction angiogram before planning a retreatment. Routine use of MRA to follow small aneurysms should wait better estimation of its performance in this particular subgroup.

Detailed imaging of the normal anatomy and pathologic conditions of the cavernous region at 3 Tesla using a contrast-enhanced MR angiography

INTRODUCTION

The purpose of this study was to evaluate the potential of a high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 Tesla for the delineation of the cavernous sinus (CS) anatomy both under normal and under pathological conditions.

METHODS

Fifteen patients without pathologies in the CS and ten patients with pituitary adenomas were included. The CE-MRA was performed on a 3-Tesla scanner and analyzed collaboratively by two readers. The cranial nerves (CNs) within the CS, namely CNIII, CNIV, CNV1, CNV2, and CNVI, were identified in both patient groups. In the adenoma patients it was also assessed whether and to which extend the adenoma invaded the CS and the spatial relationship between tumor and CNs was determined.

RESULTS

In the patients with normal CS anatomy, CNIII could be identified in 100%, CNIV in 86.7%, and CNV1, CNV2, as well as CNVI in 100% of analyzed sides. Pituitary adenomas invaded the CS unilaterally (right side) in four patients, and bilaterally in six patients. In patients with adenomas, the CN could be identified and differentiated from the tumor in the following percentages: CNIII in 100%, CNIV in 70%, both CNV1 and CNV2 in 90%, and CNVI in 100%. In all these cases, the tumor-nerve spatial relationship could be visualized.

CONCLUSIONS

3-Tesla CE-MRA allows detailed imaging of the complex anatomy of the CS and its structures. In adenoma patients, it clearly visualizes the spatial relationship between tumor and CNs, and thus might be helpful to optimize presurgical planning.

A prospective trial of 3T and 1.5T time-of-flight and contrast-enhanced MR angiography in the follow-up of coiled intracranial aneurysms

BACKGROUND AND PURPOSE

Endovascularly coiled intracranial aneurysms are increasingly being followed up with noninvasive MRA imaging to evaluate for aneurysm recurrences. It has not been well-established which MRA techniques are best for this application, however. Our aim was to prospectively compare 4 MRA techniques, TOF and CE-MRA at 1.5T and 3T, to a reference standard of DSA in the evaluation of previously endovascularly coiled intracranial aneurysms.

MATERIALS AND METHODS

Fifty-eight subjects with 63 previously coiled intracranial aneurysms underwent all 4 MRA techniques within 8 days of DSA. There were 2 outcome variables: coil occlusion class (class 1, complete; class 2, dog ear; class 3, residual neck; class 4, aneurysm filling) and change in degree of occlusion since the previous comparison. Sensitivity and specificity were computed for each MRA technique relative to the reference standard of DSA. Differences among the MRA techniques were evaluated in pair-wise fashion by using the McNemar test.

RESULTS

For the detection of any aneurysm remnant, the sensitivity was 85%-90% for all MRA techniques. Sensitivity dropped to 50%-67% when calculated for the detection of only the class 3 and 4 aneurysm remnants, because several class 3 and 4 remnants were misclassified as class 2 by MRA. CE-MRA at 1.5T and 3T misclassified fewer of the class 3 and 4 remnants than did TOF-MRA at 1.5T, as reflected by the significantly greater sensitivity for larger aneurysm remnants with CE-MRA relative to TOF-MRA at 1.5T (P = .0455 for both comparisons).

CONCLUSIONS

CE-MRA is more likely than TOF-MRA to classify larger aneurysm remnants appropriately. We recommend performing both CE-MRA and TOF-MRA in the follow-up of coiled intracranial aneurysms and at 3T if available.

MR angiographic follow-up of intracranial aneurysms treated with detachable coils: evaluation of a blood-pool contrast medium

BACKGROUND AND PURPOSE

Blood-pool agents are promising in the imaging of small vessels with slow or complex flow. Our aim was to compare blood-pool contrast-enhanced MR angiography (BPCE-MRA) using gadofosveset trisodium (Vasovist) with 3D time-of-flight MRA (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular therapy.

MATERIALS AND METHODS

We included 32 patients with a total of 37 coiled aneurysms. MRAs in the early steady-state phase were performed on a 1.5T scanner within 8 days of digital subtraction angiography (DSA). Two radiologists independently analyzed TOF-MRA and BPCE-MRA images. Consensus was reached by review involving a third neuroradiologist. DSA images were interpreted separately by an interventional radiologist. Findings were assigned to 1 of 3 categories: 1) complete occlusion, 2) residual neck, and 3) residual aneurysm.

RESULTS

Follow-up DSA demonstrated 13 complete obliterations (class 1), 13 residual necks (class 2), and 11 residual aneurysms (class 3). Weighted kappa statistics showed substantial concordance of TOF-MRA and DSA (0.664) as well as BPCE-MRA and DSA (0.724) ratings. Comparison between TOF-MRA and BPCE-MRA found excellent agreement (0.818) with only 6 (16.2%) discrepancies. For detecting residual flow, the difference in accuracy of both MRA techniques (83.8% versus 91.9%) was not significant (McNemar, P = 1.000). BPCE-MRA showed a tendency towards higher sensitivity and specificity (91.7% and 92.3%, respectively) compared with TOF-MRA (87.5% and 76.9%).

CONCLUSIONS

In classifying the completeness of endovascular cerebral aneurysm therapy, we found that BPCE-MRA and 3D TOF-MRA showed very good agreement. The use of Vasovist did not lead to a significantly increased accuracy of MRA follow-up.

Evaluation of the occlusion status of coiled intracranial aneurysms with MR angiography at 3T: is contrast enhancement necessary?

BACKGROUND AND PURPOSE

MR angiography (MRA) is increasingly used as a noninvasive imaging technique for the follow-up of coiled intracranial aneurysms. However, the need for contrast enhancement has not yet been elucidated. We compared 3D time-of-flight MRA (TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3T with catheter angiography.

MATERIALS AND METHODS

Sixty-seven patients with 72 aneurysms underwent TOF-MRA, CE-MRA, and catheter-angiography 6 months after coiling. Occlusion status on MRA was classified as adequate (complete and neck remnant) or incomplete by 2 independent observers. For TOF-MRA and CE-MRA, interobserver agreement, intermodality agreement, and correlation with angiography were assessed by kappa statistics.

RESULTS

Catheter-angiography revealed incomplete occlusion in 12 (17%) of the 69 aneurysms; 3 aneurysms were excluded due to MR imaging artifacts. Interobserver agreement was good for CE-MRA (kappa = 0.77; 95% confidence interval [CI], 0.55-0.98) and very good for TOF-MRA (kappa = 0.89; 95% CI, 0.75-1.00). Correlation of TOF-MRA and CE-MRA with angiography was good. The sensitivity of TOF-MRA and CE-MRA was 75% (95% CI, 43%-95%); the specificity of TOF-MRA was 98% (95% CI, 91%-100%) and of CE-MRA, 97% (95% CI, 88%-100%). All 5 incompletely occluded aneurysms, which were additionally treated, were correctly identified with both MRA techniques. Areas under the receiver operating characteristic curve for TOF-MRA and CE-MRA were 0.90 (95% CI, 0.79-1.00) and 0.91 (95% CI, 0.79-1.00). Intermodality agreement between TOF-MRA and CE-MRA was very good (kappa = 0.83; 95% CI, 0.65-1.00), with full agreement in 66 (96%) of the 69 aneurysms.

CONCLUSIONS

In this study, TOF-MRA and CE-MRA at 3T were equivalent in evaluating the occlusion status of intracranial aneurysms after coiling. Because TOF-MRA does not involve contrast administration, this method is preferred over CE-MRA.

The jugular foramen: imaging strategy and detailed anatomy at 3T

BACKGROUND AND PURPOSE

The purpose of this study was to assess how well the anatomy of the jugular foramen (JF) could be displayed by 3T MR imaging by using a 3D contrast-enhanced fast imaging employing steady-state acquisition sequence (CE-FIESTA) and a 3D contrast-enhanced MR angiographic sequence (CE-MRA).

MATERIALS AND METHODS

Twenty-five patients free of skull base lesions were imaged on a 3T MR imaging scanner using CE-FIESTA and CE-MRA. Two readers analyzed the images in collaboration, with the following objectives: 1) to score the success with which these sequences depicted the glossopharyngeal (CNIX) and vagus (CNX) nerves, their ganglia, and the spinal root of the accessory nerve (spCNXI) within the JF, and 2) to determine the value of anatomic landmarks for the in vivo identification of these structures.

RESULTS

CE-FIESTA and CE-MRA displayed CNIX in 90% and 100% of cases, respectively, CNX in 94% and 100%, and spCNXI in 51% and 0% of cases. The superior ganglion of CNIX was discernible in 89.8% and 87.8%; the inferior ganglion of CNIX, in 73% and 100%; and the superior ganglion of CNX, in 98% and 100% of cases. Landmarks useful for identifying these structures were the inferior petrosal sinus and the external opening of the cochlear aqueduct.

CONCLUSIONS

This study protocol is excellent for displaying the complex anatomy of the JF and related structures. It is expected to aid in detecting small pathologies affecting the JF and in planning the best surgical approach to lesions affecting the JF.