All breast MR examinations performed in the Breast Centre of Brotzu Hospital (Cagliari,
Italy) between September 2015 and September 2018 were identified from the Radiology Database.
All cases performing breast MR for CUPAx were recruited and clinical-diagnostic history was made from hospital imaging and clinical database.
We received approval for this study from the chief of our Department.
Ethical approval for the study,
according to the National Research Ethics Service guidelines,
was not required since it was performed retrospectively on data and images obtained during daily clinical practice.
Diagnostic work-up including lymph nodes biopsy,
mammography,
ultrasonography,
breast MR,
second look ultrasound,
breast image-guided biopsy and treatment was carefully analyzed.
We included patients referring to our Breast Diagnostic Unit or from other Services,
thus not all the patients had first level breast imaging exams performed in our Center.
A careful review of all of-site images was perfomed by our dedicated breast radiologists.
Breast MR and MR-guided breast biopsy were performed on two 1.5 Tesla (T) scanners (Signa HDxt or Signa HD,
GE Healthcare,
Waukesha,
WI,
USA) using a bilateral breast coil (8-channel phased array for the 1.5T system,
GE Healthcare,
WI,
USA) and a dedicated vacuum assisted biopsy system with 8 or 11-gauge core needles (Mammotome,
Devicor Medical Products,
Cincinnati,
USA).
After obtaining informed consent,
breast MR and MR-guided breast biopsy were performed by two dedicated radiologists with more than 15 years of experience in breast imaging.
The breast MR protocol includes:
- axial T2-weighted turbo spin-echo sequence
- 3D sagittal T1-weighted fat suppressed high definition sequence (VIBRANT) before and five runs after intravenous infusion of gadolinium contrast agent (ProHance®,
Bracco Imaging,
Italy),
0.1 mmol per kilogram at 2 ml/s chased by 20 ml of saline solution
- 3D axial VIBRANT post contrast sequence axial diffusion-weighted imaging (DWI) (B0 and B1000).
Post-processing analysis includes subtraction images,
maximum intensity projection (MIP) and multiplanar reconstruction (MPR),
dynamic enhancement curve and apparent diffusion coefficient (ADC).
The MR-guided breast biopsy protocol includes:
- 3D sagittal VIBRANT sequence before and once/twice after intravenous infusion of gadolinium contrast agent (ProHance®,
Bracco Imaging,
Italy),
0.1 mmol per kilogram at 2 ml/s chased by 20 ml of saline solution;
- 3D sagittal VIBRANT sequence post needle insertion;
- 3D sagittal VIBRANT sequence post sampling 3D sagittal VIBRANT sequence post clip placement (Mammomark,
Devicor Medical Products,
Cincinnati,
USA).
Pre-menopause women who underwent breast MRI examination were on day 6-13 of the menstrual cycle,
despite the intake of oral contraception.
Lesions were described using BI-RADS MR lexicon and were assigned to a final BI-RADS category.
Diagnostic performance on breast MR in detecting breast occult primary was evaluated and compared to literature data.