What is a Cranial Angiogram?
A cranial angiogram (also called cerebral angiogram or digital subtraction angiography/DSA) is an invasive imaging procedure that uses catheter-based injection of contrast material into the cerebral blood vessels to create high-resolution, real-time images of the brain's vascular anatomy. 1
Technical Description
The procedure involves inserting a catheter through the femoral artery (groin) or other access point, advancing it through the arterial system to the neck vessels, and injecting contrast dye directly into the cerebral arteries while taking rapid X-ray images. 2
Digital subtraction angiography (DSA) uses computer processing to "subtract" bone and soft tissue from the images, leaving only the contrast-filled blood vessels visible. 1
The technique provides three-dimensional pathoanatomical data about cerebral vasculature and allows real-time analysis of blood flow dynamics. 2
Contrast injections can be repeated during the same procedure to identify subtle vascular abnormalities and flow patterns. 2
3D rotational angiography can be performed during DSA, which has been shown to identify aneurysms in 25% of patients with previously negative 2D angiograms. 3
Clinical Role and Indications
DSA remains the gold standard for detecting and characterizing cerebrovascular lesions, with resolution, sensitivity, and specificity that equal or exceed noninvasive techniques like CTA and MRA. 1, 4
Primary diagnostic indications include:
Subarachnoid hemorrhage evaluation when CTA is negative or inconclusive, particularly with diffuse hemorrhage patterns. 3, 4
Detailed characterization of intracranial aneurysms for treatment planning, including assessment of aneurysm neck, relationship to parent vessels, and suitability for endovascular therapy. 3
Evaluation of arteriovenous malformations and dural arteriovenous fistulas, where DSA is required for definitive diagnosis. 1, 4
Assessment of arterial dissection, arteritis, and fibromuscular dysplasia, where DSA provides definitive diagnosis. 4
Problem-solving when noninvasive imaging (CTA/MRA) is inconclusive but clinical suspicion remains high for vascular injury. 1
Detection of "pseudoocclusion" in atherosclerotic disease, which cannot be accurately diagnosed with noninvasive imaging. 4
Safety Profile
The risk of permanent neurological complications from diagnostic cerebral angiography is 0.07% in patients with aneurysms, subarachnoid hemorrhage, and arteriovenous malformations. 5
The overall risk of stroke or death is less than 0.2% in the largest case series. 1, 5
Permanent neurological deficits occur in approximately 0.2-0.34% of procedures, with transient neurological events occurring in similar rates. 6, 7
Major complications include embolic stroke from catheter-induced thromboembolism, dislodgement of atherosclerotic plaque, or air embolism during catheter exchanges. 5
Non-neurological complications include groin hematoma (0.41%), contrast-induced nephropathy, and arterial dissection (0.44% asymptomatic cervical vessel dissections). 6
Emergency procedures and angiography for intracerebral or subarachnoid hemorrhage carry increased complication risks. 6
Patients with renal insufficiency and Ehlers-Danlos syndrome are at higher risk for complications. 5
Comparison with Noninvasive Alternatives
While CTA and MRA have largely replaced diagnostic angiography as screening tools, DSA remains necessary in specific clinical scenarios. 1
CTA achieves 96.3% sensitivity and 100% specificity for aneurysms ≥3mm, and 92-100% sensitivity for intracranial occlusions. 5, 8
MRA has 79% overall sensitivity but lower accuracy for small vessels and distal occlusions. 5, 8
Two concordant noninvasive studies can often obviate the need for diagnostic DSA. 1, 5
However, DSA provides superior detail for treatment planning and can detect subtle abnormalities missed by noninvasive imaging, with new clinically meaningful findings in 43% of purely diagnostic angiograms. 9
Therapeutic Extension
A major advantage of cerebral angiography is that it serves as both a diagnostic tool and a platform for immediate endovascular treatment during the same session. 3
In patients with acute subarachnoid hemorrhage, 61% were referred to endovascular treatment based on pre-procedure imaging, and 93% underwent successful coiling during the same angiography session. 3
This capability eliminates the need for a separate procedure when aneurysms or other treatable lesions are identified. 3