Martin R. Prince, MD, PhD
Gadolinium-enhanced MR Aortography’
PURPOSE: To evaluate the potential VJAGNETIC resonance (MR) angiog- ies directly with excellent contrast for preferential arterial enhancement raphy is increasingly per- and high resolution in a three-dimen- at magnetic resonance (MR) aortogra- formed as a noninvasive method of sional Fourier-transform acquisition phy with an intravenous infusion of evaluating patients with suspected optimized for the shortened Ti of the paramagnetic contrast material. vascular disease (1-3). MR angiogra- blood. The use of gadolinium chebates MATERIALS AND METHODS: phy is particularly well suited to the for enhancing MR angiognaphy has Gadolinium chebates were adminis- evaluation of low-resistance vessels been described in the intracranial cm- tered intravenously (0.2 mmol/kg) such as the carotid and intnacerebnal culation (4-9), aorta (10-13), and pom- during three-dimensional MR imag- arteries. In healthy subjects, vessels of tal vein (14) and in popliteal-tibiab ing (1.5 T) in 125 patients (77 male normal caliber have strong, continu- vessels (15). The previously reported ous laminar flow, which is readily de- problems of background tissue and and 48 female patients, aged 4-86 years [mean, 66 years]) with sus- tected with standard time-of-flight venous enhancement were avoided in pected aorta or aortic branch vessel techniques. But in patients with vas- this study by imaging during infusion disease. cuban disease that disturbs the normal of contrast material. In addition to laminar flow, time-of-flight images are demonstrating the technique, this an- RESULTS: Infusion for the duration degraded. There is loss of signal when tide evaluates the effects of infusion of the MR acquisition resulted in sig- inflow is reduced in ectatic vessels on time, dose, and differences between nificant preferential arterial enhance- in patients with low cardiac output. three currently available gadolinium ment without the confounding effects Tortuous vessels may have segments compounds. of excessive venous or background- that are not oriented perpendicular to tissue enhancement (P < 10 ). An- the plane of imaging, resulting in loss MATERIALS AND METHODS giographic or surgical correlation in of signal from in-plane saturation. 48 patients revealed an 88% sensitiv- Loss of signal also results from turbu- Theory ity and a 97% specificity for detection bent dephasing in stenoses and aneu- Gadolinium chelates are paramagnetic of stenoses or occlusions and a 100% rysms. sensitivity and a 100% specificity for agents that shorten the spin-lattice relax- These problems are exacerbated in ation time, Ti, of blood according to the detection of aortic or iliac artery an- the abdomen and pelvis, where it is equation eurysms. necessary to use a larger body coil, 1 1 CONCLUSION: Preferential arterial which results in a reduced signal-to- (1) enhancement is possible at MR aor- noise ratio. Peripheral arteries also 1,200 R < [GdJ, tography with an intravenous infu- have higher resistance with pubsatile, sion of paramagnetic contrast material. sometimes retrograde flow; this me- where 1/1,200 is the Ti of blood without sults in decreased blood signal and gadolinium, R is the relaxivity, and [Gd] is Index terms: Aorta, MR, 981.12943 #{149}Magnetic pulsatility artifacts. In addition, the the blood concentration of a gadolinium resonance (MR), contrast enhancement, considerable length of many periph- chelate. 981.12943, 9*129432 #{149}Magnetic resonance crab vessels necessitates long imaging During dynamic imaging at times (MR), vascular studies, 981.12943, 9*129432 shorter than the recirculation time, the times with time-of-flight techniques blood concentration of a gadolinium che- Radiology 1994; 191:155-164 because imaging must be performed late is determined by the intravenous infu- in a plane perpendicular to the dinec- sion rate and the cardiac output as tion of flow. I From the Department of Radiology, Massa- This article describes a method of Gd infusion rate chusetts General Hospital, Harvard Medical [Gdlarteriai = cardiac output (2) School, Boston, Mass, and the Department of MR aontography that does not de- Radiology, University of Michigan, University pend on blood inflow or blood mo- The three gadolinium chelates currently Hospitals B1D530, Ann Arbor, MI 48109-0030. tion and thereby circumvents many of available for clinical use were investigated Received August 31, 1993; revision requested the problems of conventional time-of- in this study: gadopentetate dimeglumine October 12; revision received November 4; ac- flight MR angiography. By adminis- cepted December 10. Supported in part by the (Magnevist; Berlex Laboratories, Wayne, RSNA Research and Education Fund as an tering a paramagnetic contrast agent NJ), gadoteridol (Prohance; Squibb Diag- RSNA Research Resident and by grant no. intravenously, the Ti of blood is HL46384 from the National Institutes of Health. made short compared with that of fat Address reprint requests to the author. 2 9* indicates generalized vein and artery in- (Ti = 270 msec), muscle (Ti = 600 Abbreviations: MIP = maximum intensity msec), and other background tissues. volvement. projection, Si = signal intensity, TE = echo
. RSNA, 1994 It is then possible to image the arten- time, TR = repetition time.
155 1200 0.5 Single Double 1000 Dose Dose 0.4 E