Comparative efficacy of and sequence choice for two oral contrast agents used during MR imaging.
OBJECTIVE
Our objective was to compare the efficacy of a positive and a negative oral contrast agent and to determine the optimal sequence choice for use in pelvic MR imaging.


METHODS
We undertook a prospective randomized trial of 57 patients with pelvic cancer who were examined with MR imaging after oral administration of a positive contrast agent (27 patients) or a negative contrast agent (30 patients). T1- and T2-weighted breath-hold and non-breath-hold gradient-recalled echo and turbo spin-echo sequences were obtained. Using the hard-copy images, we graded filling and distention of the small bowel, bowel wall conspicuity, delineation of normal and pathologic structures, and artifacts.


RESULTS
Good or excellent small-bowel filling and distention was obtained in 17 patients (63%) receiving the positive agent and in 26 patients (87%) receiving the negative agent, and bowel wall conspicuity was graded good or excellent in 19 patients (70%) and 20 patients (67%), respectively. Normal and pathologic structures were better delineated with the negative agent (20 patients [74%] and 27 patients [90%], respectively; p = .02). Breath-hold gradient-recalled echo T1-weighted images were preferred for the positive agent (78%), and breath-hold T2-weighted images were preferred for the negative agent (93%). Contrast artifacts were more frequently seen with the negative agent (11% and 93%, respectively; p = .0001), and such artifacts were eliminated using T2-weighted sequences.


CONCLUSIONS
Both contrast agents were effective in pelvic MR imaging, but delineation of normal and pathologic structures was better with the negative agent. Gradient-recalled echo T1-weighted sequences are recommended for positive contrast agents, and breath-hold T2-weighted sequences are recommended for negative contrast agents.
Academic Department of Diagnostic Radiology, The Royal Marsden Hospital NHS Trust and Institute of Cancer Research, Sutton, Surrey, United Kingdom.
S
S
Grubnic
A R
AR
Padhani
P B
PB
Revell
J E
JE
Husband
D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D052203:Ferrosoferric Oxide; D019786:Gadolinium DTPA / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D007422:Intestines / Q000473:pathology*; D007501:Iron / Q000008:administration & dosage* / Q000009:adverse effects; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides / Q000008:administration & dosage* / Q000009:adverse effects; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology; D012833:Siloxanes / Q000008:administration & dosage* / Q000009:adverse effects; D001749:Urinary Bladder Neoplasms / Q000473:pathology
D003287:Contrast Media; D058185:Magnetite Nanoparticles; D010087:Oxides; D012833:Siloxanes; C088769:ferumoxsil; D007501:Iron; D019786:Gadolinium DTPA; D052203:Ferrosoferric Oxide