The use of contrast-enhanced, dual-source CT angiography had diagnostic image quality at a lower radiation dose than digital subtraction CTA and high diagnostic accuracy compared with 3D digital subtraction angiography (DSA) in detecting intracranial aneurysms, according to a study published in the January issue of the American Journal of Roentgenology.
In the study, Long-Jiang Zhang, MD, department of medical imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University in Nanjing, China, and colleagues examined 46 patients with clinically suspected intracranial aneurysms who underwent dual-source CTA and 3D DSA. For purposes of analyzing image and quality and radiation dose of dual-source CTA, a control group of 46 patients who underwent digital subtraction CTA was also recruited.
The image quality of dual-source CTA and digital subtraction CTA was rated on a four-point scale—excellent, good, moderate and poor. Radiation dose of CTA was recorded according to patient protocol, while aneurysm detection with dual-source CTA compared with 3D DSA was analyzed on a per-patient and on a peraneurysm basis.
The authors found that for the 46 patients, the image quality of dual-energy CTA was moderate in three cases, good in 18 cases and excellent in 25 cases. The image quality of digital subtraction CTA was good in 12 cases and excellent in 34, according to the authors, meaning there was no statistical difference between the image quality of dual-energy CTA and digital subtraction CTA.
Patients undergoing dual-source CTA received a smaller radiation dose (volume CT dose index, 20.6 mG;dose–length product, 398.6 mGy x cm) than those undergoing digital subtraction CTA (volume CT dose index, 50.4 mGy; dose–length product, 1,095.6 mGy x cm).
As far as the diagnostic accuracy of dual-source CTA was concerned, 3D DSA showed no aneurysm in 11 patients and 40 aneurysms in 35 patients (30 had a solitary aneurysm and five had multiple aneurysms). With dual-source CTA, 38 aneurysms in 34 patients were correctly detected and two aneurysms in two patients were missed, the authors wrote.
With DSA as the standard of reference, the sensitivity, specificity and positive and negative predictive values of dual-energy CTA in the detection of intracranial aneurysm were 97.1 percent, 100 percent, 100 percent and 91.7 percent on a per-patient basis and 95 percent, 100 percent, 100 percent and 99.7 percent on a per-aneurysm basis. Dual-source CTA had sensitivities of 93.8 percent, 100 percent and 80 percent and specificities of 100 percent, 100 percent and 100 percent in the detection of aneurysms larger than 5 mm, those measuring 3.1–5 mm and aneurysms 3 mm or smaller.
The authors concluded that their preliminary data demonstrated that dual-energy CTA can eliminate bone from CTA images and clearly depict intracranial vessels in only a single contrast-enhanced acquisition with diagnostic image quality and much less radiation dose than digital subtraction CTA. Single acquisition, contrast-enhanced dual-energy CTA had high sensitivity and specificity in detecting intra cranial aneurysms compared with 3D DSA and, the authors wrote, can be a “useful tool for evaluating intracranial aneurysms.”