The diagnostic yield of repeat computed tomography angiography in cases of spontaneous subarachnoid haemorrhage after negative initial digital subtraction angiography

Abstract

Purpose: It is currently unclear how useful repeat computed tomography angiography (CTA) is in spontaneous subarachnoid haemorrhage (SAH) patients after negative initial digital subtraction angiography (DSA). The purpose of this study is to assess the yield of repeat CTA for the detection of causative vascular lesions in patients with SAH in whom there has been a negative initial DSA.

Material and methods: This observational retrospective study was carried out from January 2013 to July 2022 at a single institution. Analysis of the SAH pattern on unenhanced CT showed that patients were divided into perimesencephalic SAH and diffuse SAH groups. A repeat CTA was performed on all spontaneous SAH patients who had a nega-tive initial CTA and DSA within a 2-week period. An interventional neuroradiologist and a diagnostic radiologist examined all images to search for causative vascular abnormalities.

Results: Forty-seven patients were included in our study, with a median age of 55 years and a range of 28-81 years. Thirty-seven had diffuse SAH (66%), and 16 had perimesencephalic SAH (34%). The repeat CTA revealed 2 causa-tive vascular lesions (a right PICA aneurysm and a mycotic aneurysm) in 2 separate patients (yield of 4.3%), both of whom had diffuse SAH (yield of 6.5%). In retrospect, none of these vascular lesions were evident in the initial CTA and DSA. No evidence of re-bleeding was observed in the follow-up period.

Conclusions: It is beneficial to repeat CTA when evaluating patients with diffuse SAH who initially present with nega-tive initial DSA. For occult aneurysms, the diagnostic yield of the follow-up CTA is 6.5%.

Keywords: computed tomography angiography; digital subtraction angiography; subarachnoid haemorrhage.

Figure 1

A 70-year-old woman with infective endocarditis presents with a thunderclap headache. A) Unenhanced computed tomography demonstrates a diffuse pattern of subarachnoid hemorrhage with mild hydrocephalus. B) Frontal view of right internal carotid artery (ICA) injection of initial digital subtraction angiography (DSA) showed a focal irregularity of the temporal branch of right middle cerebral artery (MCA) by retrospective review (arrow). C) A repeated computed tomography angiography (CTA) performed 11 days after the initial DSA demonstrated interval growth of the mycotic aneurysm at the temporal branch of the right MCA (arrow). This patient underwent antibiotic treatment

Figure 2

A 62-year-old woman presents with a severe headache. A) Unenhanced computed tomography demonstrates a diffuse pattern of spontaneous subarachnoid haemorrhage (SAH), predominant in the posterior fossa. B, C) Initial digital subtraction angiography (DSA) of the right vertebral artery injection in anteroposterior (AP) and lateral views does not demonstrate a vascular abnormality. D) Follow-up computed tomography angiography (CTA) performed 9 days after DSA demonstrated a small aneurysm at the right PICA origin (arrow). E, F) Secondary DSA in AP and lateral views confirmed a right PICA aneurysm (arrow). This patient underwent a suboccipital craniotomy (SOC) to trap an aneurysm