Pseudotumours in chronic kidney disease: can diffusion-weighted MRI rule out malignancy.
OBJECTIVE
To evaluate whether diffusion-weighted MRI (DW-MRI) can distinguish pseudotumours in chronic kidney disease (CKD pseudotumours) from renal-cell-carcinomas (RCCs) (with or without CKD) and whether it offers additional benefit over conventional MRI.


METHODS
One-hundred patients underwent MDCT, MRI and DW-MRI (at b-values of 0 and 500s/mm(2)) for evaluation of focal renal lesions. Of these, 20 patients with 40 CKD pseudotumours and 36 patients with 40 RCCs were retrospectively analyzed. T1-weighted, T2-weighted, diffusion-weighted images were evaluated, apparent-diffusion-coefficient (ADC) values were compared and receiver-operating-characteristic (ROC) curves were drawn to establish cut-off ADC-values.


RESULTS
92.5% of CKD pseudotumours remained indeterminate after conventional MRI. On DW-MRI, none of them showed restricted diffusion and thus malignancy could be ruled out in 100% of the lesions. In contrast, all the solid RCCs showed diffusion restriction. Mean ADC-value for CKD pseudotumours was significantly higher than RCCs and surrounding diseased parenchyma [2.50 vs 1.56 (×10(-3)mm(2)/s) (P<0.0001) and 2.05 (×10(-3)mm(2)/s) (P=0.0001) respectively]. ROC analysis for differentiating CKD pseudotumours and RCC yielded high sensitivity (91.7%) and specificity (100%) for cut-off ADC-value of 2.04 (×10(-3)mm(2)/s).


CONCLUSIONS
CKD pseudotumors usually remain indeterminate on conventional non-contrast MRI. DW-MRI can distinguish CKD pseudotumors from RCCs and offers a non-contrast non-invasive alternative for ruling out malignancy.
Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi, India. Electronic address: ankurgoyalaiims@gmail.com.
Ankur
A
Goyal
Raju
R
Sharma
Ashu S
AS
Bhalla
Shivanand
S
Gamanagatti
Amlesh
A
Seth
D000328:Adult; D002292:Carcinoma, Renal Cell / Q000453:epidemiology / Q000473:pathology*; D015897:Comorbidity; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D005260:Female; D006104:Granuloma, Plasma Cell / Q000453:epidemiology / Q000473:pathology*; D006801:Humans; D007194:India / Q000453:epidemiology; D007680:Kidney Neoplasms / Q000453:epidemiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology / Q000473:pathology*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D055815:Young Adult
ADC; CKD; Chronic kidney disease; DW-MRI; Diffusion weighted MRI; Indeterminate renal lesion; MDCT; MRI; ROC curve; Renal cell carcinoma; Renal pseudotumour; apparent diffusion coefficient; chronic kidney disease; diffusion-weighted MRI; magnetic resonance imaging; multidetector computed tomography; receiver operating characteristic curve