Original article
Detection and characterization of unruptured intracranial aneurysms: Comparison of 3 T MRA and DSA

https://doi.org/10.1016/j.neurad.2014.08.002Get rights and content

Summary

Purpose

To compare magnetic resonance angiography (MRA) at 3 Tesla (3 T) and digital subtraction angiography (DSA) for the detection and characterization of unruptured intracranial aneurysms (UIA).

Materials and methods

This study has been approved by our local ethical committee. From February to August 2010, 40 consecutive patients with UIA contemporarily underwent MRA at 3 T including time-of-flight (TOF-MRA) and contrast enhanced (CE-MRA) techniques and DSA. MR images were independently reviewed by 3 radiologists and DSA images were reviewed by 2 radiologists together. Interobserver and intertechnique agreements were assessed for aneurysm detection and characterization including maximal diameter, neck width and the presence of a bleb or a branch arising from the sac.

Results

DS angiography revealed 56 aneurysms. Mean sensitivity and positive predictive value of MRA were 91.4% and 93.4% respectively. For UIA < 3 mm and those  3 mm, MRA had a mean sensitivity of 74.1% and 100% respectively. Intertechnique and interobserver agreements were substantial for the measurement of UIA maximal diameter (mean κ, 0.607 and 0.601 respectively) and were moderate and fair for neck width measurement respectively (mean κ, 0.456 and 0.285 respectively). For bleb detection, intertechnique and interobserver agreements were fair and slight respectively (mean κ, 0.312 and 0.116 respectively) whereas both were slight for detection of branches arising from the sac (mean κ, 0.151 and 0.070 respectively).

Conclusion

MR angiography at 3 T has a high sensitivity for the detection of UIA. However, it remains significantly inferior to DSA for morphological characterization of UIA.

Introduction

The management of patients with unruptured intracranial aneurysms (UIA) requires evaluating the balance between the risk of aneurysm rupture and treatment related morbidity and mortality [1], [2], [3]. Rupture risk is influenced by intrinsic aneurysm characteristics (e.g. location or morphology) [4], [5] and other factors such as gender, autosomal dominant polycystic kidney disease, personal or familial history of aneurysmal subarachnoid haemorrhage [6].

Digital subtraction angiography (DSA) remains the gold standard imaging method for the detection and morphological evaluation of IA [7]. However, DSA is an invasive, time consuming and expensive procedure associated with a low but significant risk of neurological deficit [8]. Magnetic resonance angiography (MRA) is a non-invasive alternative method for UIA evaluation and is now considered the first line method for the follow-up of endovascular treatment of IA with coils and/or stents [9]. At 1.5 Tesla (T), MRA has a high sensitivity for the detection of aneurysms ≥ 3 mm [10], [11], [12], [13]. However, all but one study at 1.5T [10] have compared MRA to conventional DSA without 3D rotational angiography (3DRA) that detects more very small IA [14], [15]. On the other hand, MRA presents a major limitation because it remains inferior to DSA for aneurysm morphological characterization [16]. Indeed, precise information on IA morphology is mandatory for patient triage between endovascular coil embolization and surgical clipping. Thanks to the development of MR imaging at 3 T, the diagnostic performance of MRA has been improved by optimizing the signal-to-noise ratio as well as spatial and contrast resolutions [17], [18], [19], [20], [21]. The aim of this study was to compare MRA at 3 T – including time-of-flight (TOF) and contrast enhanced (CE) techniques – and DSA including 3DRA for the detection and characterization of UIA.

Section snippets

Population

This study has been approved by our local ethical committee and written informed consent has been obtained from all patients. Between February and August 2010, we prospectively included all patients referred for one or multiple saccular UIA at our interventional neuroradiology consultation. Forty-one patients were identified of whom one patient was excluded because she refused to undergo DSA. There were 31 women and 9 men with a mean age of 52 years (range, 21 to 73 years old).

Imaging

MR angiography

Results

Mean delay between DSA and MRA was 21.5 days whereas the median delay was one day.

Discussion

This study shows that MRA at 3 T has a high sensitivity for the detection of UIA. Moreover, its sensitivity is equal to that of DSA for aneurysms ≥ 3 mm. However, MRA remains inferior to DSA for the characterization of UIA.

Conclusion

MR angiography at 3 T has a high sensitivity – equal to that of DSA for IA  3 mm – for the detection of UIA. However, it remains significantly inferior to DSA for morphological characterization of UIA.

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.

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