Department of Radio-diagnosis. Trichy SRM Medical College Hospital and Research Centre. Irungalur, Trichy, Tamil Nadu, India

*Corresponding author:Krishna Kumar M, Department of Radio-diagnosis. Trichy SRM Medical College Hospital and Research Centre. Irungalur, Trichy, Tamil Nadu, India. E-mail Id: drmkrishnakumar@gmail.com

Copyright: © 2026 Kumar K, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article Information:Submission: 07/01/2026; Accepted: 15/04/2026; Published: 18/04/2026

Objective: Saccular (berry-shaped) aneurysms that develop at arterial bifurcations—branch points where an artery splits into two branches—are the most common type of intracranial aneurysms, which are aberrant focal dilatations (localized bulges) of cerebral arteries. When they burst, cerebral artery aneurysms (CAA) pose a serious risk of morbidity and death. This case series aims to analyze computed tomography cerebral angiography (CTCA), a medical imaging method for the screening, diagnosis, and follow-up of patients with cerebral artery aneurysms that uses CT scans to show cerebral arteries.
Conclusion: Recent years have seen a significant change in the diagnosis and treatment of cerebral aneurysms. With CTCA, radiologists can accurately describe pertinent results, such as the risk of aneurysm rupture, and reliably and noninvasively identify the majority of intracranial aneurysms. Additionally, it helps identify high-risk groups and recommend screening. Treatment is becoming safer and more efficient thanks to nonoperative endovascular treatments, which are minimally invasive operations carried out inside blood vessels.

Keywords:Subarachnoid Hemorrhage; Fusiform Aneurysm; Dolichoectasia; Bilobed Aneurysm; Mycotic Aneurysm; Giant Aneurysm; Computed Tomography Cerebral Angiography

Although the majority of cerebral artery aneurysms [CAA] may not cause any symptoms over a patient’s lifetime, ruptures can have disastrous consequences. About 80–90% of nontraumatic subarachnoid hemorrhages (SAH) are caused by them (Figures 1A, 2A, 2B, 3A, 4A, 4B, 5A, 5B, 6A, 6B, and 7A). Position, size, high-danger characteristics (irregular protrusions and/or daughter sacs), patient characteristics (age, gender, race), and extra risk factors (hypertension, prior SAH, smoking) all influence the rupture hazard of CAA [1]. Saccular (berry) aneurysms are the most common type of intracranial aneurysms, and they are found in predictable locations around the circle of Willis. However, uncommon aneurysm types can occasionally be found, such as dissecting, fusiform, serpentine, blood blister type, traumatic, mycotic (or infectious), atheromatous, and enormous aneurysms, all of which can cause focal bleeding (Figure. 1A, Figure 8A, 9A), thromboembolic episodes, or bulk effect [2] (Figure. 10A). Conventional neurovascular imaging techniques such as CTCA, magnetic resonance angiography (MRA), and digital subtraction angiography (DSA) can be used to assess CAA, morphologic features, and post-treatment appearance. The diagnostic accuracy of noninvasive imaging for initial opinion and surveillance has improved with to advancements in computed tomography and CTCA, transcranial Doppler sonography, and MRA, even if DSA is still the gold standard for CAA characterisation and treatment planning. Hospitalization for aneurysmal subarachnoid hemorrhage decreased slightly but significantly with increased use of neuroimaging and treatment of unruptured CAA.
We examine the CTCA imaging methods and manifestations of CAA in this patient population’s assessment, monitoring, management, and results.

Approximately 4% of people have intracranial aneurysms, making them fairly common. The majority of these aneurysms are asymptomatic, but they do present a slight but real risk of rupturing and causing acute SAH [3].
The internal elastic lamina and a weakened or absent muscularis layer are typically the two layers of the normal artery wall that are lacking in all real cerebral aneurysms. All layers of the artery wall are lacking in intracranial pseudoaneurysms, which are typically cavitated paravascular hematomas that may or may not connect directly with the real arterial lumen. The “blood blister-like” aneurysm is uncommon yet deadly because of its tissue-paper thin wall. Round or lobulated focal outpouchings known as saccular aneurysms typically develop at major artery bifurcations, which are regions of severe hemodynamic stress [3].
In the arteries of the circle of Willis, saccular aneurysms usually affect the following arteries in order of frequency [4]. The middle cerebral artery (20%) (Figure1, Figure 2, Figure 9, Figure 13, Figure 24), the anterior communicating artery (30%) (Figure 3, Figure 4, Figure 7, Figure 10, Figure 11, Figure 12, Figure 23), the internal carotid artery (8%) (Figure 6, Figure 13, Figure 14, Figure 15, Figure 16, Figure 17, Figure 18, Figure 20), and the tip of the basilar artery (Figure 21), Pericallosal anterior cerebral artery (4%) (Figure 8, 12) and posterior inferior cerebellar artery (3%). Fusiform aneurysms (Dolichoectasia) (Figure 25) are long, spindle-shaped arterial dilations that may be linked to non-atherosclerotic pathology, such as connective tissue disorders, or atherosclerotic vascular disease [3]. Ectatic sinuous cerebral arteries, which are most commonly found in the vertebrobasilar system, give rise to dolicoectasia, which can have a diameter of several centimeters. Although symptoms of brainstem or cranial-nerve compression are typically present in these situations, they are not typically linked to SAH [5]. A ruptured artery or cystic medial necrosis are the causes of dissecting aneurysms. Thirty percent of affected people develop multiple aneurysms [5] - According to the Unruptured Cerebral Aneurysm Study [6], aneurysms should be classified as small (<5 mm), medium (>5-10 mm), large (>10 mm-25 mm), and giant (>25 mm) based on the maximum dome diameter. A neck diameter greater than 4 mm or a dome-to-neck ratio less than 2 were indicative of a wide-neck aneurysm.
Giant fusiform aneurysms are thought to be less common than 1% of all intracranial aneurysms, while “giant aneurysms”- intracranial aneurysms with a diameter more than 25 mm-represent between 3-5% of all aneurysms. A gigantic aneurysm presentation is characterized by the presence of a mural thrombus, cerebral bleeding episodes, and expansion symptoms [7].

Microaneurysms, also called Charcot-Bouchard aneurysms, are linked to persistent hypertension and usually develop in small blood arteries (less than 300 micrometers in diameter), most frequently the lenticulo-striate vessels of the basal ganglia [8]. Intracranial bleeding is frequently caused by Charcot-Bouchard aneurysms [9].
A family history of aneurysms, a variety of hereditary illnesses, age above 50, female gender, present cigarette smoking, and cocaine usage are all contributing factors to the development of aneurysms. Rare causes of intracranial aneurysms include head trauma, intracranial tumors or neoplastic emboli, and infections from bacterial or fungal colonization of artery walls [10].
Intracranial aneurysms have been linked to fibromuscular dysplasia, coarctation of the aorta, and pheochromocytoma, most likely due to the elevated blood pressure that these disorders induce [11].

SAH is 1.6 times more prevalent in women, making them more vulnerable to aneurysm rupture [12-14]. Only 10–15% of cerebral aneurysms exhibit symptoms [15, 16], with the majority being discovered by chance while being evaluated for other ailments. The bulk effect or possibly a little amount of blood leakage that irritates the meninges but is insufficient to qualify as a hemorrhage are the main causes of the CAA symptoms [12, 17]. Given that 10% to 43% of SAH sufferers report having a sentinel headache two months prior, these symptoms could be an early warning sign of an imminent rupture.preceding the rupture [18]. SAH patients typically have poor clinical conditions, which might include severe headaches, disorientation, neurological impairments, and even coma. With a 25% to 50% death rate, SAH is a terrible occurrence. Only about one-third of cases have a favorable outcome since over 50% of survivors experience permanent impairment [19]. According to statistics from the International Study of Unruptured Intracranial Aneurysms (ISUIA), aneurysms with a diameter of 10 mm or greater are critically vulnerable to rupture. The average annual rupture rate for aneurysms smaller than 10 mm in diameter without a history of SAH was 0.05%; however, the rupture rate was ten times higher for aneurysms of the same size with a history of SAH [20]. For the detection of cerebral aneurysms, a recent study using CTCA with a multidetector row scanner found a sensitivity of 95.1% to 98% and a specificity of 100%. The published series shown that DSA is still more sensitive than CTCA in detecting aneurysms less than 3 mm [21, 22]. In addition to screening, CTCA may identify the morphometric features of intracranial aneurysms, such as the sizes of the sac and neck as well as the existence of daughter sacs and leaving branches. An ECG-gated, time-resolved, volumetric imaging sequence, fourdimensional (4D) CTCA generates angiographic images using patientspecific average input rates with a rather excellent spatial resolution (≈0.5 mm³) [23]. The method is being applied more frequently to improve hemodynamic assessments of brain aneurysms using computational fluid dynamics (CFD). 4D CTCA has been shown in several investigations to detect specific regions of abnormal aneurysm wall motion, which may indicate a higher risk of rupture [24]. For cerebral aneurysms greater than 3 mm, the three-dimensional (3D) time-of-flight (TOF) MRA sensitivity is 93%–97%, while for aneurysms smaller than 3 mm, it is 85%-93% [25].

To see cerebral arteries and their aneurysms, 4D MR employs gadolinium contrast and TOF sequences. 4D MR uses postprocessing techniques and ECG-synchronized 3-D phase-contrast MRI to noninvasively measure 3-D intracranial blood flow [26]. In specific regions of interest, 4D MR may evaluate blood flow volumes, flow velocities, and wall shear stress (WSS). A number of modest investigations have shown that aberrant WSS may be linked to thin aneurysm walls and aneurysm development [27], which could have therapeutic implications. Research indicates that an inflammatory mechanism that results in artery wall remodeling, atherosclerotic conformation, and aneurysm growth is the cause of aneurysms [28]. Focal enhancement aneurysms are more likely to be bigger [28] and have a higher rupture risk score [29]. When evaluating unstable unruptured intracranial aneurysms, MR high-resolution vascular wall imaging (HR-VWI) has emerged as a valuable tool. The evaluation of aneurysm wall enhancement as a biomarker of aneurysm wall inflammation, aneurysm growth, and rupture shows encouraging compliance [30]. According to data, there is a significant negative predictive value for the absence of aneurysm wall augmentation. When there are several intracranial aneurysms, MR HR-VWI can assist in identifying the ruptured aneurysm and may even lead to rupture risk classification during aneurysm surveillance [31]. With 3D rotating DSA, the operator may see the aneurysm’s size, shape, and neck as well as the parent-vessel properties in more detail. Additionally, this method is helpful in obtaining suitable working angles for potential endovascular expected anatomy and embolization following open surgical surgery [32, 33]. With the exception of vascular overlap, 4D DSA allows 3D viewing from any chosen spatial projection at any moment throughout the passage of the contrast bolus for aneurysm investigation [34]. Due to early IVUS catheters’ enormous size and poor navigability, intravascular ultrasonography (IVUS) has been limited in its ability to evaluate cerebral disease. Furthermore, IVUS is known to overestimate the true lumen’s size, which could be caused by inadequate lumen–intima interface imaging [35]. An alternative intravascular imaging method called optical coherence tomography (OCT) employs interferometry and light

backscatter to see the architecture of the artery wall and lumen with a spatial resolution ten times greater than that of DSA or IVUS [36]. OCT can scan lumen size, intimal flaps, patency of perforators and tiny branches, stent apposition, thrombus development, endothelialization, and all layers of the artery wall with an axial resolution of 10 to 20 μm, which may be useful in predicting aneurysm rupture [37]. The 2D and 3D morphology of aneurysms can be evaluated in a variety of ways, such as aneurysm width, perpendicular height, maximum height (from the midpoint of the neck), numerous lobes, blebs, aneurysm angle, aneurysm volume, neck width aspect ratio (height divided by neck width), and parent-vessel diameter size ratio (maximum diameter to parent-vessel diameter) [38]. The following suggestions are included in the American Heart Association [39] consensus guidelines for the standardized reporting on imaging for intracranial aneurysms and endovascular repair: 1. When there are several aneurysms, each one needs to be explained separately. 2. High-resolution planar reconstructed images are used to provide aneurysm dome measures in millimeters in three orthogonal planes. To prevent attenuating the precise lumen size and morphology, the source images shouldn’t be over-windowed. 3. The location of the aneurysm is described on the base of the neck origin vessel and, often, the nearest branchship. For example, the closest branch vessel, such as the meningo-hypophyseal trunk, superior hypophyseal, ophthalmic, anterior choroidal, or posterior communicating artery, or position at the carotid terminus, should be used to name ICA aneurysms. Bony landmarks, such as the supraclinoid, should not be used for description since they are less accurate. 4. Although additional coordinate planes (anterior or posterior, superior or inferior, medial or lateral) are also frequently used, aneurysm orientation can be characterized as right of midline, midline, or left of midline. It is also necessary to discuss the impacts of mass on nearby structures.

5. Neck sizes smaller than 4 mm and aneurysm dome-to-neck ratios larger than 2:1 indicate aneurysm morphology that can be coiled. The neck’s dimensions in comparison to the parent vessel diameter is also an important determinant for use of intraluminal adjunctive devices or flow diverters.
When using flow diverters or intraluminal adjunctive devices, vessel diameter is another crucial factor. The best way to visualize complex aneurysm morphology is via 3D volume-rendering software. The three management approaches are surgical clipping, endovascular coiling, and observation (Figure 26). Fusiform aneurysms are currently treated using a variety of techniques, including bypasses, vascular stents, wrapping, and trapping. Treatment for cerebral aneurysms is becoming safer and more efficient thanks to nonoperative endovascular methods. It is debatable what should be done when cerebral aneurysms remain unruptured. The initial interval imaging is typically obtained after three to six months of treatment, since most aneurysm recurrences happen in the first year after treatment [40]. The subsequent picture is taken between six months and a year later if it is stable at that point. Imaging may be stretched out to intervals of one to five years if the aneurysm continues to show stability. Higher-threat aneurysms require a longer (perhaps lifetime) follow-up period [41]. The gold standard for vascular imaging, DSA is typically chosen for the first follow-up imaging following aneurysm therapy. For long-term surveillance, MRA is the preferred noninvasive imaging technique. Since gadolinium contrast carries a relatively low risk [39], CE-MRA is typically chosen. The acquisition duration is quicker than TOF-MRA, and TOF-MRA is less sensitive for aneurysms that perfuse slowly [42]. Because there is less susceptibility artifact associated with stents and flow diverters with high metal surface coverage and flow-related signal loss is eliminated by the use of contrast material, the CE-MRA exhibits better detection of post-treatment intracranial aneurysm occlusion, parent vessel visualization, and luminal measurements even though its inherent spatial resolution is lower than that of the 3D TOF technique [43]. Although CTCA is an inexpensive, noninvasive substitute for MRI, beam hardening artifacts from clips, coils, and stents severely impair the image quality [44].

The diagnosis, monitoring, therapy, and post-treatment monitoring of cerebral aneurysms all depend on imaging. In order to more precisely guide implicit treatment, it is crucial to accurately assess the size, morphology, position, and rupture status of a cerebral aneurysm as well as to identify certain imaging characteristics that may indicate a higher risk of rupture. The majority of intracranial aneurysm morphologies may be accurately and noninvasively diagnosed by radiologists using CTCA quickly in emergency room setting, which is necessary to select the best course of action. Therefore, it seems that employing CTCA as the main imaging technique for SAH is a successful strategy, and DSA should only be used in situations when there is doubt. Non-invasive imaging techniques like as transcranial Doppler sonography, CTCA, and MRA are more suitable for serially monitoring aneurysms because of invasive angiography’s risks. Treatment for cerebral aneurysms is becoming safer and more efficient thanks to nonoperative endovascular procedures.

Kumar K, Raveendran C, Murugaiah V, Senthilnathan V. Computed Tomography Cerebral Angiography Evaluation of Cerebral Arterial Aneurysms-Case Series. Indian J Appl Radiol. 2026;12(1): 231.