Renal structure in early autosomal-dominant polycystic kidney disease (ADPKD): The Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP) cohort.
BACKGROUND
Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by gradual renal enlargement and cyst growth prior to loss of renal function. Standard radiographic imaging has not provided the resolution and accuracy necessary to detect small changes in renal volume or to reliably measure renal cyst volumes. The Consortium for Radiologic Imaging Studies in Polycystic Kidney Disease (CRISP) is longitudinally observing ADPKD individuals using high-resolution magnetic resonance (MR) imaging to determine if change in renal and cyst volumes can be detected over a short period of time, and if they correlate with decline in renal function early in disease.


METHODS
Standardization studies were conducted in phantoms and four subjects at each participating clinical center. After, in the full-scale protocol, healthy ADPKD individuals 15 to 45 years old with creatinine clearance>70 mL/min underwent standardized MR renal imaging, renal iothalamate clearance, comprehensive clinical evaluation, and determination of 24-hour urinary albumin and electrolyte excretion. Stereology was used from T1-weighted images to quantify renal volume, and region-growing thresholding was used from T2-weighted images to determine cyst volume. Renal structures were evaluated in relation to demographic, clinical, and biochemical variables using means/medians, standard deviations, and Pearson correlations.


RESULTS
Reliability coefficients for MR renal and cyst volume measurements in phantoms were 99.9% and 89.2%, respectively. In the full-scale protocol, 241 ADPKD individuals (145 women and 96 men) were enrolled. Total renal, cyst, and % cyst volume were significantly greater in each decade group. Hypertensive individuals demonstrated greater renal, cyst, and % cyst volume than normotensive subjects. Age-adjusted renal (r = -0.31, P < 0.0001), cyst (r = -0.36, P < 0.0001), and % cyst volume (r = -0.35, P < 0.0001) were inversely related to glomerular filtration rate (GFR). Age-adjusted renal volume (r = 0.42, P < 0.0001), cystic (r = 0.39, P < 0.0001, and % cyst volume (r = 0.41, P < 0.0001) were related with urinary albumin excretion.


CONCLUSIONS
MR measures of renal and cyst volume are reliable and accurate in patients with ADPKD. ADPKD is characterized by significant cystic involvement that increases with age. Structure (renal and cyst volume) and function (GFR) are inversely related and directly related with the presence of hypertension and urinary albumin excretion in individuals with normal renal function.
Chapman
Arlene B
AB
Department of Medicine (Renal Division), University of Alabama at Birmingham, Birmingham, Alabama, USA. arlene_chapman@emory.org
Guay-Woodford
Lisa M
LM
Grantham
Jared J
JJ
Torres
Vicente E
VE
Bae
Kyongtae T
KT
Baumgarten
Deborah A
DA
Kenney
Philip J
PJ
King
Bernard F
BF
Glockner
James F
JF
Wetzel
Louis H
LH
Brummer
Marijn E
ME
O'Neill
W Charles
WC
Robbin
Michelle L
ML
Bennett
William M
WM
Klahr
Saulo
S
Hirschman
Gladys H
GH
Kimmel
Paul L
PL
Thompson
Paul A
PA
Miller
J Philip
JP
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000150:complications; D007668:Kidney / Q000473:pathology* / Q000503:physiopathology; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D019047:Phantoms, Imaging; D016891:Polycystic Kidney, Autosomal Dominant / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology