乳腺磁共振成像-山大影像所.ppt

乳腺磁共振成像MRI OF BREAST 史浩 山东省医学影像学研究所 PREFACE MAMMOGRAPHY PITFALLS The sensitivity is between 69% and 90%. The specificity ranges from 10% to 40%. Tumours may be missed because of poor mammographic technique or observer error, or the size and nature of the lesions relative to the surrounding breast tissue, which may obscure them. ULTRASOUND PITFALLS US has limitations as a screening modality because microcalcification in ductal carcinoma in situ may not be identified. The false negative rate is ranging from 0.3% to 47% in some series. It is difficult to ensure that the entire breast has been imaged. US is time consuming. MRI ADVANTAGES Excellent soft tissue resolution Tomographic imaging Multiple orientations High spatial resolution Lack of ionizing radiation Grading the cancer of breast DISADVANTAGES Lower sensitivity to calcification Expensive Examination fee Longer examination time Infection of heart movement and respiration EXAMINATION INDEX 钼靶或超声不能确诊的病灶 区分术后疤痕和肿瘤复发 要保留乳腺的乳腺癌患者，查找其它隐藏肿瘤，明确肿瘤范围，确定手术区域 评价隆胸术后硅树胶植体的完整性及乳腺病变情况 MRI TECHNIQUE COILS dedicated breast coil single or double breast mode EXAMINATION TIME After menopause No time request Before menopause Sixth to Sixteen days of the menstrual cycle Or avoiding six days before and after menses POSITION The prone position will decrease the amount of respiratory motion artifact. Minimal compression applied within the coil will decrease motion artifact. PHASE-ENCODING DIRECTION The phase encoding direction should not pass anterior to posterior, but from left to right, to ensure that cardiac activity is not projected over the breast. SATURATION GATING Saturation zone is located behind thoracic wall Cardiac and respiratory gating SCANNING PLANES Transverse plane Coronal plane Sagittal plane CONVENTIONAL SEQUENCES T1WI T2WI STIR (Fat suppression sequences) SPECIAL SEQUENCES 3D FLASH (fast low angle shot) PWI (Perfusion Weighted Imaging) CSI (Chemical shift imaging) SCAN PARAMETERS Thickness: 2mm~5mm Gap: 0~3mm M