Policeni, Bruno

Objective: Aneurysm growth is considered predictive of future rupture of intracranial aneurysms. However, it is still unknown how accurately neuroradiologists can reliably detect incremental aneurysm growth using clinical magnetic resonance imaging (MRI) imaging. The purpose of this study is to assess the agreement rate of detecting aneurysm enlargement using generally used MRI imaging modalities. Methods: Three silicone flow phantom models each with eight aneurysms of various sizes in different sites were used in this study. The aneurysm models were identical except for an incremental increase in size of the 8 aneurysms ranging from 0.4mm to 2mm. The phantoms were imaged on 1.5 tesla (T) and 3T MRI units with both time-of-flight (TOF) and contrast enhanced magnetic resonance angiography (MRA). Three independent expert neuroradiologists measured the aneurysms in a blinded fashion utilizing different measurement approaches. The individual and agreement rate among the three experts in detecting aneurysm enlargement were calculated. Results: The average detection rate of any increase in any aneurysmal dimensions was 95.7%. The detection rate for the three readers (A, B and C) was 98.0%, 96.6% and 92.7%, respectively ( P =0.22). The detection rate in each MRI modality was 91.3% using 1.5 T TOF, 97.2% using 1.5T gadolinium (Gad), 95.8% using 3.0T TOF and 97.2% using 3.0T Gad ( P =0.31). As the incremental enlargement value increased, the detection rate for aneurysm enlargement increased. Use of Gad in 1.5T improved the detection rate in small incremental enlargement (e.g. 0.4 - 1mm) of the aneurysm ( P =0.04). The locations of the aneurysms also affected detection rate for aneurysm enlargement ( P <0.0001). Conclusions: The detection rate and interobserver agreement was very high for aneurysm enlargement of 0.4mm to 2 mm. Detection rate of any increase in any aneurysmal dimensions did not depend on the choice of MRI imaging modalities and measurement protocols.

OBJECTIVEAneurysm growth is considered predictive of future rupture of intracranial aneurysms. However, how accurately neuroradiologists can reliably detect incremental aneurysm growth using clinical MRI is still unknown. The purpose of this study was to assess the agreement rate of detecting aneurysm enlargement employing generally used MRI modalities.METHODSThree silicone flow phantom models, each with 8 aneurysms of various sizes at different sites, were used in this study. The aneurysm models were identical except for an incremental increase in the sizes of the 8 aneurysms, which ranged from 0.4 mm to 2 mm. The phantoms were imaged on 1.5-T and 3-T MRI units with both time-of-flight (TOF) and contrast-enhanced MR angiography. Three independent expert neuroradiologists measured the aneurysms in a blinded manner using different measurement approaches. The individual and agreement detection rates of aneurysm enlargement among the 3 experts were calculated.RESULTSThe mean detection rate of any increase in any aneurysmal dimension was 95.7%. The detection rates of the 3 observers (observers A, B, and C) were 98.0%, 96.6%, and 92.7%, respectively (p = 0.22). The detection rates of each MRI modality were 91.3% using 1.5-T TOF, 97.2% using 1.5-T with Gd, 95.8% using 3.0-T TOF, and 97.2% using 3.0-T with Gd (p = 0.31). On the other hand, the mean detection rate for aneurysm enlargement was 54.8%. Specifically, the detection rates of observers A, B, and C were 49.0%, 46.1%, and 66.7%, respectively (p = 0.009). As the incremental enlargement value increased, the detection rate for aneurysm enlargement increased. The use of 1.5-T Gd improved the detection rate for small incremental enlargement (e.g., 0.4–1 mm) of the aneurysm (p = 0.04). The location of the aneurysm also affected the detection rate for aneurysm enlargement (p < 0.0001).CONCLUSIONSThe detection rate and interobserver agreement were very high for aneurysm enlargement of 0.4–2 mm. The detection rate for at least 1 increase in any aneurysm dimension did not depend on the choice of MRI modality or measurement protocol. Use of Gd improved the accuracy of measurement. Aneurysm location may influence the accuracy of detecting enlargement.