K. Suga et al., Functional assessment of canine kidneys after acute vascular occlusion on Gd-DTPA-enhanced dynamic echo-planar NM imaging, INV RADIOL, 36(11), 2001, pp. 659-676
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
RATIONALE AND OBJECTIVES. To assess the alteration in renal transit of gado
linium diethylenetriaminepentaacetic acid (Gd-DTPA) in dog kidneys after ac
ute vascular occlusion on dynamic echo-planar imaging (EPI).
METHODS. Dynamic 240-ms EPI series (repetition time/echo time/inversion tim
e [TR/TE/TI] = 3000/42.1/100 ms) of the midcoronal plane of both kidneys of
dogs anesthetized by intravenous administration of phenobarbital sodium an
d ketamine hydrochloride were obtained before and after ligation of the lef
t renal vein (n = 6) or artery (n = 6) for 40 minutes after a 2-second-rate
bolus injection of a 0.05 mmol/kg dose of Gd-DTPA. Renal Gd-DTPA transit w
as analyzed on the time-Delta R2* curves in each layer of the outer cortex
(OC), juxtamedullary cortex and outer zone of the medulla (JMC-OM), and the
inner zone of the medulla (IM). The results were compared with those in si
x normal animals and those of a fast gradient-echo TI-weighted dynamic stud
y performed in other vein- (n = 6) or artery- (n = 6) occluded animals and
six normal animals. The histopathological basis of the altered Gd-DTPA tran
sit was also evaluated.
RESULTS. The dynamic EPI showed rapid Gd-DTPA transit through each of the f
ive concentric layers, with three separate peaks on the time-Delta R2* curv
es. The vein-occluded kidneys showed immediate swelling, with a significant
increase in the cross-sectional area proportion of the JMC-OM layer compar
ed with normals (32% +/- 2% vs 24% +/- 2%, P < 0.0001) and intensely conges
ted capillaries, tubular, obliterated material, and gradual and persistent
enhancement of the OC and JMC-OM layers but poor Gd-DTPA migration to the I
M layer. The artery-occluded kidneys showed a significant reduction in the
entire cross-sectional area compared with normals (1352 +/- 69 vs 1432 +/-
47 mm(2), p < 0.05) and poor enhancement, with significant decreases in the
area under the time-Delta R2* curve of the OC and JMC-OM layers compared w
ith the vein-occluded kidneys (79 +/- 50 vs 324 +/- 108 and 82 +/- 42 vs 32
6 +/- 113, respectively; both P < 0.0001), despite minimal histological dam
age. In both models, the nonaffected kidneys showed significant increases i
n the area under the time-Delta R2* curves compared with baseline. The time
course of vascular and tubular Gd-DTPA transit was more detailed by the EP
I study than by the T1-weighted imaging study.
CONCLUSIONS. Echo-planar imaging has an excellent ability to follow the rap
id, renal Gd-DTPA transit through the regional anatomy of the canine kidney
. After venous occlusion, the JMC-OM layer may be the most affected site, p
rimarily causing renal swelling and interruption of tubular Gd-DTPA transit
and concentration. In contrast, an initial block of vascular Gd-DTPA inflo
w is the primary effect of arterial occlusion. Nonaffected kidneys seem to
compensate by increasing excretion of Gd-DTPA.