Elsevier

Clinical Radiology

Volume 60, Issue 5, May 2005, Pages 565-572
Clinical Radiology

Detection and evaluation of intracranial aneurysms with 16-row multislice CT angiography

https://doi.org/10.1016/j.crad.2004.09.012Get rights and content

AIM

The aim of this study was to assess the usefulness of 16-row multislice CT angiography (CTA) in evaluating intracranial aneurysms, by comparison with conventional digital subtraction angiography (DSA) and intraoperative findings.

METHODS

A consecutive series of 57 patients, scheduled for DSA for suspected intracranial aneurysm, was prospectively recruited to have CTA. This was performed with a 16-detector row machine, detector interval 0.75 mm, 0.5 rotation/s, table speed 10 mm/rotation and reconstruction interval 0.40 mm. CTA studies were independently and randomly assessed by two neuroradiologists and a vascular neurosurgeon blinded to the DSA and surgical findings. Review of CTA was performed on workstations with an interactive 3D volume-rendered algorithm.

RESULTS

DSA or intraoperative findings or both confirmed 53 aneurysms in 44 patients. For both independent readers, sensitivity and specificity per aneurysm of DSA were 96.2% and 100%, respectively. Sensitivity and specificity of CTA were also 96.2% and 100%, respectively. Mean diameter of aneurysms was 6.3 mm (range 1.9 to 28.1 mm, SD 5.2 mm). For aneurysms of less than 3 mm, CTA had a sensitivity of 91.7% for each reader. Although the neurosurgeon would have been happy to proceed to surgery on the basis of CTA alone in all cases, he judged that DSA might have provided helpful additional anatomical information in 5 patients.

CONCLUSION

The diagnostic accuracy of 16-slice CTA is promising and appears equivalent to that of DSA for detection and evaluation of intracranial aneurysms. A strategy of using CTA as the primary imaging method, with DSA reserved for cases of uncertainty, appears to be practical and safe.

Introduction

Intra-arterial digital subtraction angiography (DSA) remains the accepted gold standard for the diagnostic work-up of suspected intracranial aneurysms. Concerns over the small but potentially significant risk of permanent neurological complications associated with DSA has generated growing interest in the use of alternative non-invasive techniques, among which CT angiography (CTA) has emerged as the method of choice.1, 2 The advantages of CTA have been well described previously.2 CTA is safe, relatively inexpensive and can be performed immediately after routine un-enhanced CT of the brain with a single bolus of intravenous contrast medium, thereby allowing rapid diagnosis and treatment decisions. Moreover, images of diagnostic quality can be acquired swiftly in confused or uncooperative patients, obviating the need for intravenous sedation or general anaesthesia for the lengthier DSA. Early studies of CTA using single-slice technology have, however, shown limited diagnostic accuracy in the detection of small aneurysms less than 3 mm in diameter.3, 4, 5, 6, 7 Over the last few years, implementation of multidetector row spiral CT technology has led to considerable improvement in the quality and spatial resolution of 2D and 3D reconstructions, which can now easily be viewed in any direction with commercially available workstations and software. Recent studies reporting on the use of four-detector row multislice CTA have generally shown promisingly high accuracy for the detection of small aneurysms as well as excellent depiction of morphological characteristics and related surgical anatomy.8, 9, 10 The main objective of this study is to report our early experience with 16-detector row multislice spiral CTA in the detection and pretreatment evaluation of intracranial aneurysms compared with DSA or findings at surgery or both, and coiling.

Section snippets

Subjects

Between March and October 2003, consecutive adults who were scheduled for conventional DSA for suspected intracranial aneurysm were prospectively recruited in the study to have a CTA examination. The study was approved by the local ethics committee. Written informed participant consent or relative's assent was obtained in all cases.

Imaging protocols

Conventional four-vessel DSA was performed by one of three attending neuroradiologists, on a digital angiographic unit (Angioskop, Siemens, Erlangen, Germany) via

Population

A total of 57 subjects (26 women, 31 men, mean age 53 years, range 22 to 81 years) was prospectively recruited and completed both examinations. One man was excluded because he refused consent. In another case, the CTA examination was abandoned because extravasation of contrast material caused local pain at the injection site after an intravenous cannula malfunctioned. Clinical indications for DSA were as follows: SAH on CT (n=45), xanthochromia on lumbar puncture (n=7), strong clinical

Discussion

There have been previous concerns regarding the ability of single-slice spiral CTA to detect small aneurysms of less than 3 mm in diameter.3, 4, 5, 6 A systematic review published in 1998, focusing mainly on single-slice spiral CTA, found an alarmingly low sensitivity of 61% for such aneurysms.3 Recent initial reports of first-generation four-detector row multislice CTA have been generally encouraging, although a cut-off of 2 mm has emerged as the size below which aneurysm detection may be

Acknowledgements

We are grateful to H. Szutowicz, M. Varley, T. Lewis, G. Wright, R. Holloway, K. Austen and C. Streater of Addenbrooke's Hospital for their general support and expertise.

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G. Tipper and J.M. U-King-Im are equal first co-authors of this manuscript.

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