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What causes diminished corticomedullary differentiation in renal insufficiency?
Author(s) -
Lee Vivian S.,
Kaur Manmeen,
Bokacheva Louisa,
Chen Qun,
Rusinek Henry,
Thakur Ravi,
Moses Daniel,
Nazzaro Carol,
Kramer Elissa L.
Publication year - 2007
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20878
Subject(s) - medullary cavity , cortex (anatomy) , medulla , renal medulla , renal cortex , medicine , renal function , kidney , population , nuclear medicine , urology , pathology , biology , environmental health , neuroscience
Purpose To investigate whether the loss of corticomedullary differentiation (CMD) on T1‐weighted MR images due to renal insufficiency can be attributed to changes in T1 values of the cortex, medulla, or both. Materials and Methods Study subjects included 10 patients (serum creatinine range 0.6–3.0 mg/dL) referred for suspected renovascular disease who underwent 99m Tc‐diethylene triamine pentaacetic acid (DTPA) renography to determine single kidney glomerular filtration rate (SKGFR) and same‐day MRI, which included T1 measurements and unenhanced T1‐weighted gradient echo imaging. Corticomedullary differentiation on T1‐weighted images was assessed qualitatively and quantitatively. Results SKGFR values ranged from 3.5 to 89.4 mL/minute based on radionuclide studies. T1 relaxation times of the medulla exceeded those of renal cortex by 147.9 ± 176.0 msec (mean ± standard deviation [SD]). Regression analysis showed a negative correlation between cortex T1 and SKGFR (r = −0.5; P = 0.03), whereas there was no significant correlation between medullary T1 and SKGFR. The difference between medullary and cortical T1s correlated significantly with SKGFR (r = 0.58; P < 0.01). In all five kidneys with a corticomedullary contrast‐to‐noise ratio (CNR) <5.0 on T1‐weighted images, SKGFR was less than 20 mL/minute. Conclusion In our subject population, loss of CMD with decreasing SKGFR can be attributed primarily to an increased T1 relaxation time of the cortex. Medullary T1 values vary but do not appear to correlate with degree of renal insufficiency. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.