MR Breast Implant Imaging

Welcome to the eLearning MR Breast Implant Imaging.  This course will introduce you to: Basic information and recommendations for implant imaging Different techniques used to suppress signal from the breast tissue  Tips on how to recognize which type of implants are present  Key markers that the system provides to confirm the implant type Steps to manually set the frequency when performing breast implant studies Imaging sequences used to evaluate breast implants By the end of this course you will be able to: Identify patient positioning and set-up for imaging Identify different sequences used for breast MR implant imaging Perform system adjustments for different types of implants Demonstrate suppression techniques Identify visual differences between silicone and saline implants Silicone Saline FDA approval Saline implants (May 2000) Silicone implants (November 2006) Recommendations Regular screening exams Source: www.fda/gov Construction of implant Filler Patch or fill - valve Shell (lumen) Characteristics of the implant Shell surface Shape Profile Size (volume) Shell thickness Single Lumen/ T2 with Water Sat Double Lumen/T2 with Water Sat Construction of implant Single lumen Double lumen Saline/Silicone + Saline Implants - STIR Potential for rupture – Saline Silent ruptures Collapsed silicone implant - STIR Potential for rupture – Silicone Silent ruptures Symptomatic ruptures Submuscular – T2 Subglandular – T2 Pectoral Muscle Potential for rupture – Silicone Silent ruptures Symptomatic ruptures Breast MRI should be performed with a dedicated breast MRI Coil   Breast coil should have higher SNR, good homogeneity, and signal penetration System – Coils parameter card Breast coil elements Screen patients for contraindications and safety concerns   Purpose of MR exam Implant integrity only Soft tissue evaluation / lesion detection   Type of implant Silicone or saline   History of surgery During the breast exam the patient is prone   Compression to touch   Patient can be positioned head or feet first depending upon your MR System and coil plug configuration Suppression Techniques Fat Saturation (fat sat) Fat protons saturated by frequency-selective RF pulses Magnet homogeneity affects fat sat Water saturation Frequency - selective excitation of water with subsequent de-phasing to suppress water signal Fat or Water Saturation Contrast parameter card Fat saturation – select fat sat under ‘Fat suppression’ Water saturation – select water sat under ‘Water suppression’ Only one suppression method can be selected at a time Inversion Recovery (STIR) Signal dependent relaxation time of tissue TI for Silicone suppression ~300ms at 1.5T   180° – 90° – 180° RF pulse scheme Inverts longitudinal magnetization in the opposite direction STIR with Water Saturation Suppresses two peaks IR technique – suppresses Fat or Silicone Water Sat – suppresses Silicone or Water Water Excitation Two or more RF pulses used to excite water protons only   First RF pulse excites both fat and water  Due to difference in resonant frequencies – de-phasing begins   Another RF pulse sent to hit fat Only water displayed Two peaks – fat and water Saline Implants Three peaks – silicone, fat and water Silicone Implants Implants are commonly different sizes and shapes: Fibrous scar capsule forms around implant Appearance of breast may change after initial implantation Large Silicone Implants Huge silicone peak and “very small: water and fat peaks Float cursor over peaks to see location Look at images Fat saturation challenging Not most important sequence when performing implant evaluation Assume Silicone System looks for three peaks   Check only if positive patient has silicone implants AutoCoverage: (Automatic segmentation, AutoFoV & AutoSlice) – Based on the localizer data an automatic segmentation is performed Allows an estimation of the optimal FoV (entire FoV for both breasts, right or left breast, breast with chest) User can predefine for every protocol individually which parameters shall be automatically adjusted; i.e., Time or slice thickness shall remain constant Implant situation – Based on implant type identification scan User can visually select or modify the exam dependent on the actual implant type and laterality. System automatically modifies the scan queue accordingly and the frequency adjustment setting of the protocols is changed (assume dominate fat or silicone) Applications and Case Studies   T2 Axial T2 Sag Fat Saturation Axial STIR Fluid Axial STIR + WS Mammography – difficult to evaluate implants Implants do not interfere with lesion detection Silicone tends to be very dark Due to relative closeness of frequency peak to fat Somewhat affected by fat saturation Silicone Silicone Saline Saline Silicone Saline Silicone Leak Pectoralis Optimized silicone peak detection High resolution 3D bilateral VIEWS Patient with silicone implants, proven DCIS right breast Sequence Choice of Radiologists T2 Axial T1 FLASH 3D Axial with Fat Sat T2 Sagittal Water Saturation Fat suppression not needed to evaluate implant leaks versus folds Cysts Axial STIR T2 Axial T2 Sagital WS T1 3DFL Fat Sat Axial STIR Axial STIR + WS         T2 Sag Silicone Sat* T2 Sag FS *Water Saturation with manual frequency centered on silicone peak   Left breast – Silicone rupture? Yes Right breast – Silicone rupture? Look at sagittal images                             T2 Sagittal FS T2 Sagittal FS Rupture? No Rupture / Leak Fold in implant Axial STIR Axial STIR + WS Fold Lateral Lateral Medial Axial STIR Silicone Implant (+ 20 years ago) Post Mastectomy with Flap Reconstruction Right implant Shows beginning of collapse Left implant Shows total collapse and “Linguine” Axial STIR T2 Silicone Sat Sag (Water Saturation with manual frequency centered on silicone peak) T2 Sagittal Silicone Axial STIR Axial STIR + WS Fill Valve T1 3DFL FS Dynamic STIR Axial T2 Axial Lesion Silicone Peak Tick mark:  System's center frequency Fat Water Frequency Values Silicone 600 Hz from water at 3T 300 Hz from water at 1.5T Fat 440 Hz from water at 3T 220 Hz from water at 1.5T White tick mark Displays center frequency peak selected   Frequency (temp) [Hz] Temporary center frequency numerically displayed, can be modified   Frequency (sys) [Hz] indicates System center frequency numerically, can NOT be modified Right Mouse Click within spectral display Select – Zoom x 5 Easier viewing of small peaks Right Mouse Click within spectral display Select – Zoom x 5 Easier viewing of small peaks Center cursor on Fat Peak   Left mouse click on Fat Peak   After clicking on Fat Peak, new frequency (temp) graphically indicated by line   By numerical value Frequency (temp) graphically Frequency (temp) numerical Center cursor on Fat Peak   Left mouse click on Fat Peak   After clicking on Fat Peak, new frequency (temp) graphically indicated by line   By numerical value Frequency (temp) graphically Frequency (temp) numerical Add 220 Hz (1.5T) or 440 Hz (3T) to Frequency (temp)   New Frequency (temp) delivers fat saturation pulse directly over fat peak   Select Apply Updates Frequency (temp)   Select Continue Silicone Implant imaging   Fat and water need to be suppressed to evaluate implant for rupture or linguine sign   TIRM (STIR) sequence TI set for fat suppression Select water saturation under contrast tab   Confirm frequency box pops up Click on water peak – saturates water   TI set suppresses fat Water saturation suppresses water Only silicone seen Axial STIR Axial STIR Axial STIR + Water Sat TI set to suppress fat Both water and silicone are bright Gives good overall impression of breast tissue TI set to suppress fat Both water and silicone are bright Gives good overall impression of breast tissue Water saturation pulse Centered on water peak Suppresses water signal from breast parenchyma and blood vessels   Highly sensitive for free silicone that may have leaked outside implant Bright silicone against black background Water Saturation T2 Sagittal with Water Saturation Center frequency on silicone peak Saturates silicone Bright saline, dark silicone Inversion Recovery Stir with Water Sat STIR TI at 170 Silicone Implant Saline + Silicone Implant Inversion Recovery STIR with Water Saturation Bright silicone with dark fat signal and black saline / water signal Inversion Recovery with TI 400 ms Gray silicone with bright saline and bright fat STIR + WS IR with TI 400MS Water saturation can be applied to almost any sequence Choose the sequence/select Water Saturation on the Contrast Card Water saturation suppresses the centered peak Silicone Suppression using Water Saturation Using water suppression to saturate silicone instead of water When frequency window pops up, left mouse click on frequency peak you want to suppress Select  Apply to save frequency change Select Continue to begin sequence Silicone Fat Water Real Fat Sat frequency Area standard fat sat sends the saturation pulse (220 Hz on a 1.5T) 0.000273 MHz Float cursor over peaks to check positions Fat peak is at -273 Hz from Water Silicone peak is at -347 Hz from Water Confirm silicone or saline implants even though frequency values not quite as expected Use to optimize fat saturation and silicone suppression 0.000273 MHz 0.000347 MHz Fat Peak Silicone Peak