Differentiation between complex renal cyst and renal cell carcinoma by MRI, diffusion weighted imaging and apparent diffusion coefficient in comparison with histopathology
Authors:   Department of Radiology, College of Medicine, University of Babylon, Babylon, Iraq, Hamad Zahraa Naser , Abdulsattar Osama Ayad ,   Department of Radiology, College of Medicine, University of Babylon, Babylon, Iraq, Jody Mohammed Redha ,   Department of Surgery, Al-Hilla Surgical Hospital, Babylon health directorate, Ministry of Health, Babylon, Iraq
Published: December 2024

Background. The most frequent renal masses that are accidentally discovered during abdominal radiological imaging for various clinical causes are renal cysts. MRI used to visualize the kidneys and staging tumors in local setting. DWI and ADC maps become more familiar and has gained a definitive roles in the evaluation of renal masses. The study aimed to evaluate the radiological findings of complex renal cysts and renal cell carcinoma and to differentiate between these lesions by MRI, DW-MRI and ADC in comparison with histopathology. Methods. A comparison combine prospective-retrospective study of 18 individuals with renal lesions were enrolled in this study using MRI, DWI and ADC during a period from 26th July 2023 to 29th May 2024. Participants data included age, sex, MRI mass size, DWI, ADC maps diagnosis by MRI and histopathology diagnosis. MRI was done at 1.5 Tesla (MR Systems Achieva 1.5T TX, Philips, Netherlands). MRI findings were analyzed by two professional specialist radiologist have more than 15 years' experience. DWI diffusion in enhancing lesions was recorded and ADC maps were obtained. All lesions were proven histopathologically. Results. The most of masses were malignant (13, 72.2%) while benign masses were 5 (27.8%). The overall mean ADC of masses was 1.45± 1.28 × 10-3 mm2/s (median = 1.08 × 10-3 mm2/s). Abscesses were recorded in 3 (16.7%) patients. RCC found in 8 (44.4%) of patients, which proven by histopathology. The mean ADC was greater in benign masses than malignant masses (2.58±2.16 vs. 1.02±0.15 × 10-3 mm2/s) with strong significant difference (p=0.014). The mean ADC for the 5 benign masses were: (0.97 × 10-3 mm2/s ±0.31) for abscesses and (2.99 × 10-3 mm2/s ±0.68) for complex cyst. The mean ADC for the 13 malignant masses were as followed: RCC (1.07 × 10-3 mm2/s ±0.08), Oncocytoma (1.07 × 10-3 mm2/s ±0.007), Lymphoma (0.635 × 10-3 mm2/s) and Nephroplastoma (0.80 × 10-3 mm2/s). The ADC cut off value was (1.07 × 10-3 mm2/s), with a sensitivity of 84.62% and specificity of 80.00%. Accuracy rate was 83.33%, which was statistically significant (95%CI (0.152-0.972), P<0.001), and the AUC was (0.562). Conclusions. Most of renal masses detected by MRI are malignant than benign. The most common malignant lesion is RCC and the most common benign lesion is abscesses. The differentiation between malignant and benign renal masses by MRI-DWI and ADC is equally in effectiveness of histopathology diagnosis. Significantly, the mean ADC was greater in benign masses than malignant masses (2.58±2.16 vs. 1.02±0.15 × 10-3 mm2/s). The complex cyst has greatest mean ADC value (2.99 × 10-3 mm2/s ±0.68). The mean ADC in RCC is higher than Oncocytoma, Lymphoma and Nephroplastoma. All malignant lesions have high DW and all are restricted.