17– 20 CTA is a fast, reliable, accessible, and relatively inexpensive technique that can be performed on acutely ill patients with minimal or no sedation and little associated risk. 12– 16ĬTA Techniques for the Evaluation of Clipped Aneurysms: EfficacyĪ number of reports show that multidetector CTA is increasingly replacing catheter-based angiography for the preoperative diagnosis and surgical planning for patients with both ruptured and unruptured aneurysms. However, by using the newest generation of scanners and modern techniques, CTA is emerging as a tool for the noninvasive evaluation of the cerebral vasculature after surgical clipping. The metal composition of the clip interferes with x-ray penetration, resulting in artifacts that degrade imaging of the adjacent tissues. 11 Although some adjustments in MRA parameters, such as short echo time, may reduce magnetic susceptibility artifacts, MRA is not of consistent utility in the evaluation of the perianeurysmal region following surgical clipping.ĬT is not devoid of relative drawbacks in the evaluation of the clipped aneurysm either.
10 On the other hand, MR angiography (MRA) remains limited for the evaluation of aneurysms after surgical clipping due to the substantial artifacts created by the available surgical clips, which usually completely obscure the immediate perianeurysmal region. MR imaging continues to be the technique of choice for the evaluation of subtle clinical abnormalities not explained by CT in patients with MR–compatible aneurysm clips. 2– 9 These data support the use of routine periodic imaging surveillance after successful surgical clipping.Īlthough imaging after surgical aneurysm clipping has traditionally been achieved with conventional catheter-based angiography, CT angiography (CTA) may provide an acceptable alternative in many cases, particularly for long-term postoperative follow-up.Īvailable Noninvasive Imaging Techniques and Their Utility in the Assessment of Clipped AneurysmsĬT imaging of the brain is routinely used for the perioperative assessment of patients treated with aneurysm clips to evaluate hemorrhage, infarction, hydrocephalus, and mass effect.
Although the risk for recurrence of a clipped aneurysm is low, there is evidence that aneurysm recurrence as well as de novo aneurysm formation with subsequent subarachnoid hemorrhage can occur even after successful surgical treatment. 1 In the setting of recent subarachnoid hemorrhage, imaging surveillance for cerebral vasospasm is also necessary. In the intraoperative or immediate postoperative period, imaging is required to evaluate aneurysm residual and parent vessel compromise.
Vascular imaging plays an important role in the perioperative and postoperative evaluation of cerebral aneurysms that are treated by surgical clipping. Despite these advances, conventional angiography remains the gold standard for the evaluation of surgically treated aneurysms and should be liberally used to resolve any cases of diagnostic uncertainty on noninvasive imaging. Using the latest multidetector row scanners and optimized imaging parameters, CTA can often effectively depict and follow small aneurysm remnants demonstrate patency, stenosis, or vasospasm in the adjacent parent vessels and provide surveillance of the entire cerebrovasculature for de novo aneurysms after surgical clipping. SUMMARY: Although not useful for the evaluation of coiled aneurysms, CT angiography (CTA) is far superior to MR angiography (MRA) for the evaluation of aneurysms after surgical clipping.