Aortic dissection diagnosed on stroke computed tomography protocol: a case report

Abstract

Background: Aortic dissection is one of the causes of stroke. Because cerebral infarction with aortic dissection is a contraindication to intravenous recombinant tissue plasminogen activator (rt-PA) therapy, exclusion of aortic dissection is necessary prior to its administration. However, imaging takes time to provide a diagnosis, possibly causing delays in surgical treatment.

Case presentation: A 65-year-old Japanese female patient was transported to the hospital for a suspected stroke, with back pain and left upper and lower extremity palsy which occurred while eating. Upon arrival at the hospital, the left lower limb paralysis had improved, but the left upper limb paralysis remained. Right back pain had also developed. A plain head computed tomography (CT) scan performed 110 minutes after onset showed no acute bleeding or infarction. Subsequent CT perfusion (CTP) showed acute perfusion disturbance in the right hemisphere without infarction, known as ischemic penumbra. The four-dimensional maximum-intensity projection image reconstructed from CTP showed a delayed enhancement at the right internal carotid and right middle cerebral arteries compared to the contralateral side, suggesting a proximal vascular lesion. Contrast helical CT from the neck to abdomen revealed an acute aortic dissection of Stanford type A with false lumen patency. The dissection extended to the proximal right common carotid artery. The patient underwent an emergency total arch replacement and open stent graft. After recovering well, the patient was ambulatory upon discharge from the hospital. The combination of plain head CT, CTP, and helical CT scan from the neck to abdomen enabled us to evaluate for stroke and aortic dissection within a short amount of time, allowing for early therapeutic intervention.

Conclusions: When acute stroke is suspected due to neurological deficits, plain head CT is the first choice for imaging diagnosis. The addition of cervical CT angiography can reliably exclude stroke due to aortic dissection. CTP can identify ischemic penumbra, which cannot be diagnosed by plain head CT or diffusion-weighted magnetic resonance imaging. These combined stroke CT protocols helped us avoid missing an aortic dissection.

Keywords: Acute aortic dissociation; Acute cerebral infarction; Computed tomography perfusion; Stroke.

Fig. 1

The patient’s chest radiograph shows no enlargement of the mediastinum. There is no calcification of the aortic wall or pleural effusion

Fig. 2

A plain head computed tomography scan does not reveal any sign of acute infarction or bleeding

Fig. 3

On computed tomography perfusion scan, delay (DLY), time to peak (TTP), and mean transit time (MTT) are elongated. Cerebral blood flow is decreased, but cerebral blood volume (CBV) is preserved in the region of the right middle cerebral artery. The lesions with elongated DLY, TTP, and MTT may indicate major vessel occlusion. An area with decreased CBV is diagnosed as an infarction, which is irreversible ischemic tissue damage. Because CBV remained almost normal, we determined that the patient had a large ischemic penumbra and no infarction yet in this case

Fig. 4

Computed tomography angiography reconstructed from computed tomography perfusion scan shows the right middle cerebral artery poorly depicted. The right internal carotid artery appears to be intact

Fig. 5

Four-dimensional maximum-intensity projection image reconstructed from computed tomography perfusion scan. a, b The right internal carotid artery and the right middle cerebral artery indicate delayed enhancement compared to the contralateral side. c In the late phase, the distal middle cerebral artery also exhibits delayed enhancement, and no stenosis or obstruction is observed, suggesting a proximal vascular lesion. d No venous abnormality was seen in venous phase

Fig. 6

Contrast computed tomography from the neck to abdomen was taken using a contrast medium. a A cross section at the level of the thoracic aorta revealed an acute aortic dissection of Stanford type A with false lumen patency. b A cross section of the aorta to the level of the renal artery bifurcation. The left renal artery is perfused by the false lumen. c Coronal reconstruction section of the neck. The dissection extends to the proximal right common carotid artery, with narrowing of the lumen of the right internal carotid artery