Comparison of superb microvascular imaging (SMI) and contrast-enhanced dynamic magnetic resonance imaging (MRI) in the diagnosis of breast masses

COMPARISON OF SUPERB MICROVASCULAR IMAGING (SMI) AND CONTRAST-ENHANCED DYNAMIC MAGNETIC RESONANCE IMAGING (MRI) IN THE DIAGNOSIS OF BREAST MASSES Dr. Ahmet Yasin Yitik Our study is prospective and cross-sectional, aimed at comparing the diagnostic accuracy of superb microvascular imaging (SMI) and dynamic contrast-enhanced breast magnetic resonance imaging (MRI) in diagnosing breast masses based on histopathological results, and evaluating the effectiveness of SMI in diagnosing breast lesions. After obtaining approval from the ethics committee, patients presenting with complaints of breast masses at Pamukkale University Medical Faculty Hospital between April 2022 and March 2024 underwent gray-scale ultrasonography, SMI, and dynamic contrast-enhanced breast MRI. Initially, gray-scale ultrasonography (USG) and SMI methods were applied to the patients. The next day, dynamic contrast-enhanced breast MRI was performed. During the Superb microvascular imaging procedure, free ROI (region of interest) was drawn to encompass the entire lesion, and vascular index (VI) measurements were automatically performed by the device. The measurements were conducted by a 5-year radiology resident and sent to PACS (Picture Archive Communicating Systems). At least three measurements were taken from each lesion, and the average of the three most suitable measurements was included in the study. Breast MRI and gray-scale ultrasonographic examinations were evaluated according to their BI-RADS classification by a consensus between a radiologist with 25 years of experience in breast radiology and a 5-year radiology resident. All findings were compared with histopathological diagnosis results. The study included 110 patients (aged 16-80 years, mean 47.67±13.57 years) and 112 lesions. Histopathologically, 62 lesions were benign, and 50 lesions were malignant. In gray-scale ultrasonographic examination, 58% of malignant masses had irregular shapes, 98% had irregular margins, 86% were not parallel oriented, 96% had a hypoechoic, and 64% had acoustic shadowing. Among benign lesions, 90.3% were oval-round shaped, 56% had circumscribed margins, 77.4% were parallel oriented, 54.8% had a hypoechoic, and 90.3% had no acoustic shadowing. The ultrasonographic examination achieved a sensitivity of 86%, a specificity of 64.38%, and an accuracy rate of 70.5%. The VI values were significantly higher in malignant masses (p<0.001). When the VI cut-off value was accepted as 4.15, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated as 92%, 60%, 64.8%, 90.2%, and 74%, respectively. Additionally, a significant relationship was found between VI values and the morphological characteristics of the lesion in USG, including margin characteristics, orientation, echogenicity, and presence of acoustic shadowing (p<0.05). However, no statistically significant relationship was found between the VI value and lesion shape (p>0.05). A high degree of statistically significant positive correlation was also found between lesion size and the freely drawn ROI (p<0.001). In our study, all lesions reported as BI-RADS 4a in gray-scale USG with VI values below the cut-off (4.15) were benign according to histopathological diagnosis. In dynamic contrast-enhanced breast MRI examination, 76% of malignant lesions had irregular shapes, 62% had spiculated margins, 88% showed heterogeneous contrast enhancement, and 64% had type 3 contrast enhancement kinetic curves. Among benign lesions, 46.8% were oval-round shaped, 80.6% had circumscribed margins, 77.4% showed homogeneous contrast enhancement, and 74.2% had type 1 contrast enhancement kinetic curves. The sensitivity, specificity, PPV, NPV, and accuracy of the MRI examination were calculated as 98%, 80.65%, 80.3%, 98%, and 88.39%, respectively. A significant correlation was found between VI values and MRI contrast enhancement kinetic curve types (p<0.001). In three of the four lesions with no contrast enhancement observed in MRI, flow was detected in SMI. In conclusion, the evaluation of the VI parameter obtained by the SMI technique alongside gray-scale ultrasonography and dynamic MRI findings has been shown to be beneficial in distinguishing benign from malignant breast masses. Keywords: Superb microvascular imaging, breast cancer, dynamic contrast-enhanced breast MRI, ultrasonography, breast imaging.