Early experience with spiral CT in the diagnosis of intracranial aneurysms.

We report experience with 16 patients undergoing spiral CT Scans for the evaluation of cerebral aneurysms. There were 10 females and six males, aged between 36 and 73 years. The three-dimensional scanning was useful in five situations: (i) Suspicion of aneurysm on conventional scan. An aneurysm was found in one of four patients and later confirmed by angiography, and two showed arterial ectasia with no saccular aneurysm; the fourth again appeared to have an aneurysm, but this was not shown on angiography. (ii) Follow-up of previously detected aneurysms not planned for surgery. This has been done in three patients, the spiral CT findings correlating well with previous angiography. (iii) Follow-up of aneurysm remnants after surgery (three cases); findings correlate well with previous angiography, and clips cause no artefact problems. (iv) Detection of ruptured aneurysms. In two cases, small aneurysms were found that had been missed on angiography, and in a third, with doubtful angiographic findings, spiral CT was useful. (v) Investigation of patients with past treated aneurysms, or of relatives. Three subjects have been screened so far for that purpose; in one a small aneurysm has been found, and confirmed angiographically.

Spiral CT scanning in the detection and evaluation of aneurysms of the Circle of Willis.

PURPOSE: To assess the utility of spiral computed tomography (CT) with three-dimensional reconstruction in defining aneurysms of the Circle of Willis. METHODS: Eighty-one patients with angiographic or surgical correlation were studied between 1993 and 1995, with surface rendered reconstructions of the arteries of the Circle of Willis. RESULTS: Spiral CT was useful in six clinical situations: further assessment in cases with CT suspicion of an aneurysm, follow-up of known untreated aneurysms or aneurysm remnants, subarachnoid hemorrhage (SAH) with negative angiography, a past or family history of aneurysms, and improved definition of aneurysm anatomy. Ten of fifteen patients with previous surgery had no significant artifacts on the spiral study. In 66 other patients studied in search of aneurysms, the sensitivity of detection was 95% and specificity 74%. Seventeen of nineteen aneurysms 3 mm or less in size and 38 of 39 larger were detected by spiral CT. Four of thirteen patients with SAH and previous negative angiography had aneurysms identified, which were confirmed at surgery. CONCLUSIONS: There is great promise in the use of spiral CT in demonstrating aneurysms of the Circle of Willis, including very small ones. Careful detailing of scan protocols and meticulous examination of multiplanar images are needed for maximum accuracy.

Pitfalls in the use of spiral CT for identification of intracranial aneurysms.

We describe problems encountered in our first 136 patients, with 95 aneurysms, who underwent spiral CT for investigation of possible aneurysms involving the circle of Willis and adjacent major vessels, and who had surgical and/or angiographic confirmation. There were seven false-positive cases, of which the first three could be explained by operator inexperience. There were four false negatives, all small aneurysms; two were not seen because of operator error and two were hidden by an adjacent larger aneurysm. Clip artefacts prevented diagnostic studies in six of 21 postoperative studies. One aneurysm was outside the CT field of view, being on a pericallosal artery. One basilar artery tip aneurysm was excluded from the field of the CT study because of a planning error. Inspection of the axial source images is critical if the diagnosis of small or thrombosed aneurysms is to be made. Close attention to image acquisition and computer modelling is required to reduce errors in spiral CT angiography of intracranial aneurysms.

Intracranial aneurysms: evaluation in 200 patients with spiral CT angiography.

The goal of this study was to assess the usefulness of spiral CT angiography (CTA) with three- dimensional reconstructions in defining intracranial aneurysms, particularly around the Circle of Willis. Two hundred consecutive patients with angiographic and/or surgical correlation were studied between 1993 and 1998, with CTA performed on a GE HiSpeed unit and Windows workstation. The following clinical situations were evaluated: conventional CT suspicion of an aneurysm; follow-up of treated aneurysm remnants or of untreated aneurysms; subarachnoid haemorrhage (SAH) and negative angiography; family or past aneurysm history; and for improved definition of aneurysm anatomy. Spiral CTA detected 140 of 144 aneurysms, and an overall sensitivity of 97%, including 30 of 32 aneurysms 3 mm or less in size. In 38 patients with SAH and negative angiography, CTA found six of the seven aneurysms finally diagnosed. There was no significant artefact in 17 of 23 patients (74%) with clips. The specificity of CTA was 86% with 8 false-positive cases. Spiral CTA is very useful in demonstrating intracranial aneurysms.