3D digital subtraction angiography of intracranial aneurysms: comparison of flat panel detector with conventional image intensifier TV system using a vascular phantom

Abstract

Background and purpose: Compared with the image intensifier (I.I.)-TV system, the flat panel detector (FPD) system of direct conversion type has several theoretic advantages, such as higher spatial resolution, wide dynamic range, and no image distortion. The purpose of this study was to compare the image quality of 3D digital subtraction angiography (DSA) in the FPD and conventional I.I.-TV systems using a vascular phantom.

Materials and methods: An anthropomorphic vascular phantom was designed to simulate the various intracranial aneurysms with aneurysmal bleb. The tubes of this vascular phantom were filled with 2 concentrations of contrast material (300 and 150 mg I/mL), and we obtained 3D DSA using the FPD and I.I.-TV systems. First, 2 blinded radiologists compared the volume-rendering images for 3D DSA on the FPD and I.I.-TV systems, looking for pseudostenosis artifacts. Then, 2 other radiologists independently evaluated both systems for the depiction of the simulated aneurysm and aneurysmal bleb using a 5-point scale.

Results: For the degree of the pseudostenosis artifacts at the M1 segment of the middle cerebral artery at 300 mg I/mL, 3D DSA with FPD system showed mild stenoses, whereas severe stenoses were observed at 3D DSA with I.I.-TV system. At both concentrations, the FPD system was significantly superior to I.I.-TV system regarding the depiction of aneurysm and aneurysmal bleb.

Conclusion: Compared with the I.I.-TV system, the FPD system could create high-resolution 3D DSA combined with a reduction of the pseudostenosis artifacts.

Fig 1.

Photograph (A) and schematic drawing (B) of the anthropomorphic vascular phantom used in this study. The phantom was designed to simulate the intracranial arteries with a total of 32 aneurysms. Of 32 aneurysms, 15 had an aneurysmal bleb with diameter of 2 mm.

Fig 2.

3D DSA from the superior and right posterior oblique view at 300 mg I/mL obtained with FPD system (A) and with I.I.-TV system (B). 3D DSA with FPD system shows mild stenosis at the M1 segment of the middle cerebral artery, whereas severe stenosis is observed on 3D DSA with I.I.-TV system (arrowheads). The pseudostenosis artifact caused the minor distortion of aneurysm on 3D DSA with FPD system, whereas the severe distortion of aneurysm on that with I.I.-TV system (arrows).

Fig 3.

Anteroposterior 3D DSA obtained with I.I.-TV system at 300 (A) and at 150 mg I/mL (B) demonstrated that the pseudostenosis artifacts are more severe at 300 than at 150 mg I/mL (arrows).

Fig 4.

Anteroposterior 3D DSA (300 mg I/mL) obtained with the FPD system (A) and with the I.I.-TV system (B) show many aneurysms. For depiction of aneurysms such as the aneurysm neck and the shape of the aneurysm, the 3D DSA with FPD system is superior to that with the I.I.-TV system.

Fig 5.

3D DSA (300 mg I/mL) from the right posterior oblique view obtained with FPD system (A) and with I.I.-TV system (B) show many aneurysmal blebs (arrows). For depiction of aneurysmal blebs, the 3D DSA with FPD system is superior to that with the I.I.-TV system.