Evaluation of carotid vessel wall enhancement with image subtraction after gadobenate dimeglumine-enhanced MR angiography.
OBJECTIVE
This study was aimed at testing the value of image subtraction for evaluating carotid vessel wall enhancement in contrast-enhanced MR angiography (MRA).


METHODS
IRB approval was obtained. The scans of 81 consecutive patients who underwent carotid MRA with 0.1 mmol/kg of gadobenate dimeglumine were reviewed. Axial carotid 3D T1-weighted fast low-angle shot sequence before and 3 min after contrast injection were acquired and subtracted (enhanced minus unenhanced). Vessel wall enhancement was assigned a four-point score using native or subtracted images from 0 (no enhancement) to 3 (strong enhancement). Stenosis degree was graded according to NASCET.


RESULTS
With native images, vessel wall enhancement was detected in 20/81 patients (25%) and in 20/161 carotids (12%), and scored 2.0+/-0.6 (mean+/-standard deviation); with subtracted images, in 21/81 (26%) and 22/161 (14%), and scored 2.5+/-0.6, respectively (P<0.001, Sign test). The overall stenosis degree distribution was: mild, 41/161 (25%); moderate, 77/161 (48%); severe, 43/161 (27%). Carotids with moderate stenosis showed vessel wall enhancement with a frequency (17/77, 22%) significantly higher than that observed in carotids with mild stenosis (1/41, 2%) (P=0.005, Fisher exact test) and higher, even though with borderline significance (P=0.078, Fisher exact test), than that observed in carotids with severe stenosis (4/43, 9%).


CONCLUSIONS
Roughly a quarter of patients undergoing carotid MRA showed vessel wall enhancement. Image subtraction improved vessel wall enhancement conspicuity. Vessel wall enhancement seems to be an event relatively independent from the degree of stenosis. Further studies are warranted to define the relation between vessel wall enhancement and histopathology, inflammatory status, and instability.
Sardanelli
Francesco
F
Department of Medical and Surgical Sciences, University of Milan School of Medicine, via Morandi 30, 20097 San Donato Milanese, Milan, Italy. f.sardanelli@grupposandonato.it
Di Leo
Giovanni
G
Aliprandi
Alberto
A
Flor
Nicola
N
Papini
Giacomo D E
GD
Roccatagliata
Luca
L
Cotticelli
Biagio
B
Nano
Giovanni
G
Cornalba
Gianpaolo
G
D000368:Aged; D002339:Carotid Arteries / Q000473:pathology*; D002340:Carotid Artery Diseases / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine