DCE MR imaging noninvasively evaluates renal function

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 - renal function map
Quantitative maps of healthy rabbit kidneys estimated from a nonlinear least squares algorithm.
Source: Radiology (doi:10.1148/radiology.13122495)

Dynamic contrast-enhanced (DCE) MR imaging may noninvasively evaluate the renal function of patients with contrast medium-induced nephropathy (CIN), according to a study published online Oct. 29 in Radiology.

CIN occurs within 48-72 hours after intravascular administration of iodinated contrast medium (CM), creating a large clinical issue. While there’s a low incidence of CIN in healthy people, the complication generally results in high in-hospital mortality and poor long-term survival for patients with preexisting chronic kidney diseases.

“In these patients, contrast medium–associated acute renal failure is considered one of the most severe complications related to the use of iodinated CM,” wrote Yu-Dong Zhang, PhD, of Jiangsu Province Hospital, China, and colleagues.

Glomerular filtration rate (GFR) is the main indicator of kidney function, but CIN is most commonly diagnosed by an increase in serum creatinine level, which is a poor marker for GFR. The researchers therefore designed a study in which they assessed the hemodynamic effect of CM on GFR by using 3D MR renography in rabbit models, as the imaging technique has previously been used to noninvasively identify single-kidney GFR.

Twelve healthy male New Zealand rabbits were used in the study, two of which were sacrificed before MR examination to ascertain renal histologic samples as controls. The remaining 10 rabbits completed four minute DCE MR imaging 24 hours before and 20 minutes after intravenous injection of iopamidol. Two experienced radiologists processed the gathered data.

Blood volume ( VB), GFR, and tubule volume ( VE) of the renal complex were then found using a two-compartment kinetic model. The maximum upslope, peak concentration, and initial 60 second area under curve of the whole kidney renogram curve were measured using semiquantitative analysis. The self-control data were then compared with a student-paired t test.

The study’s findings indicated that a high dosage of iopamidol resulted in a marked decrease in renal function, which could be detected using dynamic 3D MR renography.

“The evaluation of parameters derived from the DCE imaging data reveals a prominent decrease in renal circulation and glomerular filtration, as well as diminished  VE, owing to the administration of high-dose, nonionic, high-osmolality iopamidol,” wrote Zhang and colleagues. “This type of methodology may be helpful in assessment of patients with a potential risk for CIN.”