Evaluation of a distal pericallosal aneurysm visualized with 3-dimensional digital subtraction angiography: case report and treatment implications

BACKGROUND: Digital subtraction angiography (DSA) is considered the gold standard in the evaluation of cerebrovascular structures. Recently, 3-dimensional DSA (3D-DSA) has been increasingly used to obtain detailed information about the morphology and dimensions of intracranial aneurysms. We report the case of a patient who presented with a distal pericallosal artery aneurysm, which appeared by 2D imaging to be a fusiform, possible mycotic aneurysm. This was then revealed to be a saccular bifurcation aneurysm by 3D-DSA. This additional information changed the treatment plan for this patient from medical management to a surgical approach. CASE DESCRIPTION: The patient is a 56-year-old man with a history of hypertension and alcohol abuse with withdrawal seizures, who presented with a large intracranial hemorrhage on initial computed tomography scan. After stabilization with intracranial pressure management, the patient underwent magnetic resonance angiography and 4-vessel DSA. These initial studies showed a distal, fusiform pericallosal aneurysm consistent with a mycotic aneurysm. Rotational DSA was then used to generate 3D images of the structure that revealed a saccular bifurcation aneurysm. This enabled the decision to offer operative treatment rather than conservative medical management. DISCUSSION: This report highlights the value of 3D-DSA in establishing the appropriate treatment plan for patients with unique cerebral aneurysms. The higher resolution images used in this case provided information that was crucial in shifting the treatment focus from medical management, for what appeared to be a mycotic aneurysm by traditional DSA, to surgical intervention, for a clear hemodynamic aneurysm at a vessel bifurcation seen with 3D-DSA. Accurate pre-interventional evaluation and differential diagnosis are critical to designing the most effective lowest risk treatment plan. The standard method in the diagnosis of cerebral aneurysms has been DSA. Yet, higher resolution images of unclear or high-risk aneurysms are often required to guide clinical decision making. The emergence of new, less invasive endovascular techniques for securing intracranial aneurysms has placed greater emphasis on precisely defining the shape and dimensions of an aneurysm. Three-dimensional DSA is currently the highest resolution imaging modality available for the evaluation of intracranial aneurysms. CONCLUSION: 3D-DSA was used to evaluate a small, distal pericallosal artery aneurysm and revealed a saccular bifurcation aneurysm not visualized with magnetic resonance angiography and conventional DSA. This additional resolution permitted the team to consider a surgical approach for a patient who would otherwise have been treated medically. This high-resolution technique is particularly useful in guiding clinical decision making in the context of aneurysms that carry a relatively broad differential diagnosis, potentially high interventional risk, and unclear morphology.