Which organ should be considered a reference in diffusion weighted imaging of the abdomen?: The reproducibility of ADC measurements of the spleen and the renal cortex on a 1.5T MR

Diffusion weighted imaging (DWI) is a useful tool for the evaluation of focal lesions in the liver or kidneys, as well as for the diagnosis and assessment of the liver fibrosis process. Some reports show that the spleen and kidneys may serve as reference organs in the staging of liver fibrosis or the evaluation of focal liver lesions. The aim of the study was to determine whether the spleen and renal cortex can be used as reference organs in the DWI technique. The study group included 36 patients with no liver, spleen or renal pathologies and without any infections or hematologic disease. All the examinations were performed using a 1.5T MR unit with a conventional phased array body coil. Image interpretation and apparent diffusion coefficient (ADC) measurements were done by 3 experienced radiologists. There was a statistically significant difference between the ADC values noted by 2 of the examiners in the upper/middle and lower part of the spleen parenchyma. There were no statistically significant differences between the ADC values obtained by all 3 examiners in all the parts of each kidney. There were no statistically significant differences between the examiners' ADC values for the spleen and kidneys. The mean ADC values for the left kidney showed the highest measurement reproducibility. The study showed that the renal cortex seems to be an appropriate region for performing reference ADC measurements. Further studies on a larger group of patients and using various DWI protocols should be performed to ascertain the best conditions for maximizing the reproducibility of ADC measurements.