Improved Quality and Diagnostic Confidence Achieved by Use of Dose-Reduced Gadolinium Blood-Pool Agents for Time-Resolved Intracranial MR Angiography

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Fig 1.
Patient (71-year-old man) undergoing successive TR-MRA, spaced approximately 1 year apart, for evaluation of previously coiled left ophthalmic artery aneurysm. Images obtained after injection of SCA (A–D) and obtained with BPA (E–H). Background-subtracted (A and E) and unsubtracted (B and F) axial MIP volumes from SCA and BPA TR-MRA, respectively; C,G,D, and H are background-subtracted axial source MRA images from peak arterial phases derived from SCA (phase 7) and BPA (phase 9) examinations. Note the improved demonstration of mid and distal MCA branches in both hemispheres with administration of the blood-pool agent.
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Fig 2.
Patient (68-year-old woman) undergoing successive TR-MRA spaced approximately 1 year apart, for evaluation of angiographically documented indirect dural arteriovenous fistula (arrow). Images in A–C were obtained with injection of SCA; images in D–F were obtained with BPA. Early arterial (A, D), late arterial (B, E), and venous (C, F) axial MIP phases are presented as indicated. Qualitatively superior time-resolved angiography was scored for all temporal phases and arterial segments, with consideration to diagnostic confidence and vessel-background contrast. Note the generally delayed arrival/temporal phases with the slower administration rate of BPA.

Table 1:

Analysis of enhancement kinetics: BPA versus SCA

Category	BPA	SCA	P Value
Presence of uncontaminated arterial phase,^a %	68 ± 47	68 ± 47	1
Peak arterial phase^b (sub)	6.96 ± 1.63	6.15 ± 1.84	.023
Peak arterial phase^b (unsub)	6.96 ± 1.63	6.15 ± 1.84	.023
Peak venous phase^b (sub)	8.52 ± 1.64	8.0 ± 1.68	.123
Peak venous phase^b (unsub)	8.52 ± 1.64	8.0 ± 1.68	.123
Peak venous–peak arterial phase^b (sub)	1.56 ± 1.07	1.88 ± 1.19	.161
Peak venous–peak arterial phase^b (unsub)	1.56 ± 1.07	1.86 ± 1.18	.186

Note:—All values are reported as mean ± standard deviation; sub, unsub reflect background subtracted and nonsubtracted volumes.
↵a Percentage of cases with uncontaminated arteriographic phase (see text).
↵b Expressed in terms of average, time-resolved phase number.

Table 2:

Qualitative analysis of image quality: BPA versus SCA

Note:—All values are reported as mean ± standard deviation; 0 indicates nondiagnostic; 1, diagnosis possible but limited; 2, good; 3, excellent; sub, unsub, subtracted and nonsubtracted.
↵a Qualitative designation of diagnostic quality derived from 4-point scale (see text).
↵b Indicates percentage of cases for which background subtraction was satisfactory.