Retrospective Analysis of MRI Data in Patients Undergoing Fusion Biopsy of the Prostate

To investigate the causes of low diagnostic accuracy of MRI criteria for prostate cancer by correlation with histopathological findings from MRI-targeted fusion biopsy.

Materials and methods. A retrospective analysis of prostate MRI data was performed in 38 patients who subsequently underwent MRI-targeted fusion biopsy. All imaging studies were independently reviewed by a radiologist with 7 years of experience in prostate imaging. Identified suspicious lesions were correlated with histopathological findings from corresponding prostate biopsy samples. The causes of discordant results were systematically analyzed and categorized.

Results. The MRI studies identified 54 MRI-positive lesions that subsequently underwent fusion biopsy. Among these, 34 cases demonstrated false-positive MRI findings attributed to the following causes: localized inflammation exhibiting T2-weighted hypointensity, restricted diffusion, and early contrast enhancement (16 cases, including wedge-shaped lesions); encapsulated hyperplastic nodules (7 cases); and minimal lesion size (3 cases). Two cases resulted from overinterpretation of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI data. Systematic biopsy revealed adenocarcinoma in 24 tissue samples obtained from areas not identified as suspicious on MRI (false-negative results). Retrospective analysis of MRI findings allowed detection of subtle abnormalities in only one of these cases. The MRI demonstrated a sensitivity of 45% and positive predictive value of 37%.

Conclusion. The study results revealed substantial subjectivity in MRI data interpretation for prostate cancer diagnosis. Overdiagnosis of tumorous changes was significant, with false-positive rates of 55% in the peripheral zone (PZ) and 72% in the transition zone (TZ). The highest proportion of errors (76%) occurred in PI-RADS category 3 lesions, where 26 out of 34 false-positive findings were associated with this group. The primary cause of misdiagnosis (32% of cases) was morphologic changes caused by diffuse or localized inflammation mimicking tumor features: hypointensity on T2-weighted imaging (T2WI), restricted diffusion, and early enhancement on dynamic contrast-enhanced (DCE) MRI. In 21% of TZ cases, errors were related to insufficient attention to the complete encapsulation sign of suspicious nodules, which can be confirmed through sequential analysis of T2WI on adjacent slices. An additional 15% of false-positive results in the PZ occurred due to underestimation of wedge-shaped lesion morphology, a key differential diagnostic feature. These findings highlight the need for standardized MRI evaluation criteria, detailed analysis of lesion characteristics, and incorporation of clinical inflammation data to reduce overdiagnosis.

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