Renal Apparent Diffusion Coefficient Values in Patients with Obstructive Uropathy and High Values of Creatinine

Urinary tract obstruction that causes hydronephrosis may lead to an increased pressure proximal to the obstruction, including the tubules and the renal interstitium, thus causing tubular dysfunction, a decrease in glomerular filtration rate (GFR) and increased serum creatinine levels. Early diagnosis and treatment of obstructive hydronephrosis is important to preserve renal function. Imaging studies have a key role in diagnosis and follow-up of the renal obstruction [1]. Detailed morphological information including kidney size can be obtained from ultrasonography imaging (US). To a certain extent, renal blood-flow measurements, and intrarenal resistive index can be used to estimate the degree of obstruction. Yet, the degree of dilatation is not related to the degree of obstruction, and resistive index may be completely normal in chronic obstruction, or may be abnormal due to other renal parenchymal disease processes. Computed tomography (CT) is a method that can provide information on renal morphology, and on the site and cause of obstruction [2]. Individual renal function is usually evaluated by nuclear medicine techniques, which are considered as more reliable. However, these techniques have some disadvantages, such a low spatial resolution. GFR and effective renal plasma flow can be evaluated by this technique, but renal diffusion and perfusion cannot be assessed. All techniques suffer from similar disadvantages, i.e. not providing quantitative information. Diffusion weighted magnetic resonance imaging (DW-MRI) of the kidneys gives non-invasive information on renal function in healthy volunteers, and it is feasible in severely ill patients. Quantitative data on the degree of renal dysfunction may be obtained [3]. The purpose of this study is to evaluate the value of apparent diffusion coefficient (ADC) values from DW-MRI in patients with obstructive uropathy and elevated serum creatinine levels.