Magnetic resonance-based quantification of post-renal biopsy perirenal hematomas volumes

BACKGROUND: Percutaneous renal biopsy (PRB) is the gold standard for diagnosing nephropathies but, despite being generally safe, it carries the risk of hemorrhagic complications, particularly perirenal hematomas (PHs). Ultrasound, although commonly used, tends to underestimate hematoma volumes, whereas computed tomography (CT) accurately measures volumes but poses radiation concerns and often requires contrast media. Magnetic resonance imaging (MRI), free of these risks, offers high tissue resolution but remains underutilized for PH evaluation post-PRB. OBJECTIVES: To evaluate the utility of MRI-based segmentation techniques for accurately quantifying PH volumes after PRB, as a complementary imaging modality to ultrasound and CT. MATERIAL AND METHODS: We retrospectively analyzed MRI data from 85 patients who underwent PRB between July 2020 and May 2024. MRI-derived PH volumes were measured using manual segmentation. Clinical data were extracted from patient records, and the results were compared with data from a previous CT-based study. RESULTS: Perirenal hematoma was detected in 63 patients (74.1%) with a median volume of 26.2 mL (interquartile range (IQR): 7.2-59.3 mL), slightly smaller than CT-derived volumes (median: 38 mL, IQR: 18-85 mL). Using Spearman's rank correlation coefficient (rs), we found that serum creatinine (Cr; rs = 0.299, p = 0.039) and systolic blood pressure (SBP; rs = 0.333, p = 0.017) correlated positively with PH volume, while hemoglobin levels showed a negative correlation (rs = -0.322, p = 0.021). Hemodialysis was associated with larger PHs (odds ratio (OR) = 4.59, 95% confidence interval (95% CI): 1.20-17.58, p = 0.026); however, this finding is based on a model with modest predictive performance and requires further validation. CONCLUSIONS: Although its routine use may be limited, MRI could serve as a complementary tool for the detailed evaluation of PHs, offering a radiation-free and contrast media-free alternative to CT in clinical scenarios where immediate decision-making is not critical.