MR Body Imaging - Part 1

• Noninvasive examination that can evaluate organs, add in diagnoses, and/or monitor treatments of different organs within the abdomen and pelvis region, including but not limited to:   – liver   – biliary tracks   – pancreas   – kidneys   – spleen   – bowels   – bladder   – reproductive organs   – pelvic floor   – blood vessels   – lymph nodes   MR Body Imaging All information in this presentation is for illustration only and is not intended to be relied upon by the reader for instruction as to the practice of medicine. Any healthcare practitioner reading this information is reminded that the must their learning, training, and expertise in dealing with their individual patients. This material does not substitute for that duty and is not intended by Siemens Healthineers to be used for any purpose in that regard.   The length of time required to complete this course will vary depending on but not limited to, expertise of subject matter, reading speed, interruptions, and internet connection speed. The accrediting agency is responsible for determining the number CE credits awarded for the course.   The activity may be available in multiple formats such as web-based training and an actual live event. The ARRT does not allow CE activities such as internet courses, live event, home study programs or directed readings to be repeated for CE credits in the same or any subsequent biennium.   Any of the protocol(s) presented herein are for informational purposes and are not meant to substitute for any clinical judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education learning and experiences. • Liver   – Cirrhosis   – Hemochromatosis   – Hemosiderosis   – Fatty liver   – Characterizing focal hepatic lesions       - Cyst       - Hepatoma       - Focal nodular hyperplasia       - Hemangioma • Cholangiopancreatography (MRCP)   – Gallbladder issues - Stones, lesions or infections   – Bile and pancreatic ducts     • Pancreas   – Endocrine tumors   – Pancreatitis   – Pancreatic pseudocysts   – Pancreatic carcinoma • Intestines (bowels)   – Crohns disease   – Ulcerative colitis   – Inflammatory disease • Kidney, Ureter, and Bladder   – Renal cell carcinoma   – Renal vein and inferior vena cava tumors/lesions   – Renal cysts   – Ureter and bladder staging for malignancies   – Renal function • Pelvic Pain • Endometriosis • Fibroids • Adenomyosis • Ovarian/Cervical/Vaginal carcinoma • Masses or Tumor recurrence • Malformations & congenital anomalies • Pelvic Floor defects • Staging Prostate carcinoma • Evaluation of potential lymphadenopathy • Characterizing and evaluating testicular masses Abdominal Imaging  Sequences & Techniques • Single-shot sequences   – TurboFLASH   – HASTE • Multi-shot sequences 2D or 3D   – FLASH (GRE)   – TSE   – TrueFISP • 3D Measurements   – VIBE   – SPACE • Applications   – Localizer images   – Post contrast dynamic imaging • Multi-breath-hold techniques • Free breathing techniques • Applications   – Routine T2 Imaging   – Cholangiography (MRCP)   – Enterography • Breath-hold techniques • Multi-breath-hold techniques • Free breathing techniques • 2D or 3D Multi Slice • Applications   – Localizers   – In & Out Phase imaging   – Urograms     - Morphology • In & Out Phase imaging   – 1.5T     - In-phase TE = 4.76 ms     - Opposed phase TE = 2.38 ms   – 3T     - In-phase TE = 2.46 ms     - Opposed phase TE = 1.23 ms NOTE: Opposed phase images are collected first and then in-phase images @ 3T •  Scan Time Reduction - Single breath hold     – Decrease FoV phase     • Increase FoV Read as needed to minimize aliasing     – Decrease Phase Resolution     – Increase slice thickness and decrease number of slices     – Decrease TR if possible Note: maintain Signal-to-Noise (SNR) and Image Quality • T2 weighting Abdomen imaging   – Multi Breath-holds • Female & Male pelvic imaging • Urograms • Prostate examinations • Decrease scan time for a single breath-hold   – Decrease FoV phase     • Increase FoV Read to reduce wrap if needed   – Decrease Phase Resolution   – Increase slice thickness and decrease number of slices   – Decrease TR > Minimum of 3000 ms   • Free breathing acquisition   – Physio  Parameter Card > PACE Tab > Resp Control: Trigger   – Position Navigator pulse and slices   – Proper breathing cooperation especially during learning phase Inflammatory Bowel Disease Proctogram • T2 weighting Abdomen imaging   – Breath-hold studies reduced motion artifacts • Colonography • Myelograms • Proctograms • Urograms • 3D Gradient Echo Sequence   – Fat saturation or Water excitation     • Suppresses background signal • Applications   – Contrast Enhanced Exams   – Abdomen – Liver volumes • Post Processing   – MPR (Multi Planar Reformat) – Anatomical   – MIP (Maximum Intensity Projection) – Vascular • CAIPIRINHA – Controlled Aliasing in Parallel Imaging Results in Higher Acceleration   – Distributes k-space points more uniformly   – True 3D reconstruction   – Higher PAT factors     • Requires more oversampling • Improved image quality   – Less residual artifacts   – Lower noise amplification CAIPIRINHA x 4 Breath-hold time 7 seconds 72 slices 3 mm slice thickness • LINEAR reordering • Q-FATSAT • Base Resolution = 320   – Increases sharpness • Opposed phase TE (or near opposed phase TE) • Flip angle = 9°   – More uniform fat suppression • Phase partial Fourier = 7/8 with POCS enabled   – Only to reduce scan time • Prescan normalize filter – On Center Positioning Off-center Positioning • Coil Positioning   – Anterior Body Matrix Coil Positioning     • Coil centered over center of image and anatomy of interest • Coil Positioning   – Anterior Body Matrix Coil Positioning     • Positioned to center of imaging volume to minimize artifacts Center Positioning Off-center Positioning • Selective excitation in Phase encoding artifact   – Adjust rectangular FoV size     • Avoid excitation of arms   – Increase phase oversampling Rec FoV 100% 20% Phase Oversampling Rec FoV 65% 80% Phase Oversampling • Out-of-phase TE   – Increase bandwidth to obtain • Improves Fat Sat homogeneity • Reduces iPAT artifacts TE 2.5 ms TE 1.2 ms • Applications   – Abdominal   – MRCP free-breathing   – Pelvis Abdominal Imaging  Fat Suppression Techniques • Four contrasts in a Single Breath-hold • Check all boxes   – Fat, Water, In-phase, opposed-phase • Individual Contrasts – check boxes   – In phase   – Opposed-Phase   – Water signal   – Fat signal   – Fat & Water signal • Saturation Bands • Flow Compensation • Reduced Motion Sensitivity • Prospective Acquisition Correction (PACE) • syngo BLADE • StarVIBE • FREEZEit Abdominal Imaging  Motion Correction Techniques • Stationary Saturation Bands • Special Saturation   – Tracking Saturations     • Excited at specified distance “before” or “after” slice     • Track slice being measured   – Parallel Saturations     • Positioned       - Parallel H/F – either side parallel to slice  or slab group       - Parallel H or F – one side parallel to slice or slab group     • Does not track slice group • Prevents signal loss and smearing caused by moving spins • Selection of flow compensation is sequence dependent • Sequence > Part 1 Parameter card > Flow Compensation   – Yes – Both slice and readout directions   – Read – Read-out direction only   – Slice – Slice-selection direction only   – None – No flow comp • Reduced Motion Sensitivity   – Sequence > Part 2 Parameter Card   – TSE with PACE during free breathing     • T2-weighted abdominal applications     • Not recommended for Breath-hold examinations due to higher TF • TIP: Technique less effective for applications with higher Turbo Factors (TF) • Physio – PACE Parameter Tab >Resp. Control   – Off - Navigator control switched off   – Breath-hold - Multi Breath-hold technique   – Trigger - Free breathing technique • Respiratory Control > Breath-hold • Siemens Tree > Abdomen > library > T1, T2, or BLADE   – e.g., Diffusion sequence only available on Numaris X Software • Adequate for healthier cooperative patients   – Use Concatenations or Measurements to do multiple breath-holds • Sequence can be started in the Inline Display • Navigator echo used to track movement of diaphragm • Scout Type   – Liver Dome Scout   – Phase Scout - Default • Position Navigator   – Manual   – Automatic • Patient prep   – Instruct Patient to breath normally during entire measurement • Patient Set-up   – Ensure Body matrix coil is positioned high enough to include dome of liver   – Free breathing localizer used • Coronal Image (GSP) - Positioning   – Choose best liver dome image on coronal image     • Position Navigator (Turquoise box) – between liver and lung     • Right mouse click > Shift to Image Plane       - Navigator box will have solid lines • Axial Positioning   – Choose best image of liver dome on an axial image   – Position navigator in center of liver dome     • Box should have solid lines   – Double check on coronal image • Start Measurement • Inline display box will open • Navigator positioned correctly   – Marks learning phase – first five respiratory cycles   – Turquoise dotted box   – Turquoise line shows patients breathing motion   – Clear separated border between lung (black) and liver (light grey) • Learning Phase - Red Rectangles   – Purposed data acquisition     • Position – based on parameters     • Width – acquisition duration Tool tip - If the Width of the Red Rectangle is larger than half the breathing period (horizontal distance from maximum inspiration to maximum inspiration), terminate the measurement and reduce the acquisition duration to avoid artifacts • Imaging Phase   – Yellow rectangle (acceptance window) – expiration begins   – Green curve – detected diaphragm position   – Falls into acceptance window – 1st block of imaging sequence starts • Navigator is positioned too high into the lung • Navigator is positioned too low into the lung • Detected signal is jagged   – Reposition patient so liver dome is within area of magnet homogeneity Note: Larger patients might need to utilize Phase scout navigator   • Manual   – User must position navigator, visible in GSP segments • Automatic (Default)   – Navigator positioning is automatic and not visible in the GSP • Position Navigator   – Ensure Body Coil is positioned high enough to include dome of liver   – Free breathing localizer used • Physio > PACE   – Scout Type - Phase Scout   – Manual - Position Navigator   – Automatic – (Default) Positioned Automatically by system       - Navigator not shown in GSP segment • Position on free breathing Localizer • Position navigator within homogenous liver parenchyma • Exclude bigger vessels, if possible • Click GO to start measurement • Check if navigator is positioned correctly • Phase changes are detected – represented in breathing curve due to movement of liver during breathing cycle • Navigator intersects a large vessel   – May be unsuitable due too the pulsation of the vessel   – Terminate Measurement   – Adjust navigator • Physio > PACE Parameter Card   – Position Navigator - Automatic   – Acquisition Window - enter a new % value     • Concatenations automatically adapts to acquisition duration     • Sequence automatically adjusts to individual patient's breathing   – Sequences – TSE • Physio > PACE Parameter Card   – Position Navigator - Manual   – Acquisition Window - Time of data acquisition during breathing cycle     • Enter a fixed value in milli-seconds (ms)     • Maximum of 1/3 of the patient's breathing period   – Sequences – HASTE and SPACE • Turbo Spin Echo - Motion insensitive sequence   – TSE or Fast TSE   – Free-breathing PACE   – Minimizes motion artifacts • Applications   – Metastases   – Lymph nodes Without BLADE With BLADE Conventional TSE TF – 33 Time – 3 minutes Fast TSE TF – 43 Time – 1:52 minutes • Advantages   – Shorter Measurement Times   – Reduced Streaking with BLADE • Disadvantages   – Higher SAR than TSE   – Different slice profile • Applications   – Abdomen and Pelvis   – Free-breathing technique     • Patients unable to hold their breath   – High-resolution with increased spatial resolution • StarVIBE – Parameter Recommendations   – Siemens Tree – stored protocols   – Resolution > Common Parameter Card     • Trajectory – Radial       • Radial Views       - Approximately ≥ 1.5 times selected Base Resolution   – FoV - 100%   – iPAT – not available   – DIXON – not available • StarVIBE – Abdomen/Pelvis imaging   – 3D T1 Weighted FLASH   – Radial sampling scheme using 3D  “stack-of-stars “trajectory   – Motion-insensitive sequence   – Eliminates ghosting artifacts   – Fat Suppression options     • Quick FatSat     • SPAIR • VIBE   – Dynamic   – Liver Registration     • DynaVIBE • TWIST–VIBE Abdominal Imaging  Techniques for Dynamic Imaging • Contrast > Dynamic Parameter Card   – Measurement     • Define multiple measurements in one sequence   – Pause After Measurement     • Define delay times between individual measurements • Multiple Measurements • Liver Registration   – Activates Elastic 3D Liver Registration     • Only available with > 2 measurements • Save Original Images   – Saves unprocessed images in database   – Original unregistered images can also be saved • Original Images   – Patient with Hepatocellular Carcinoma (HCC)   – Misalignment of anatomy   – Subtracted Images – 2, 3 and 4 (1) Pre-contrast image (2) Arterial phase (3) Delayed phase (4) Portal-venous phase • Original Imaging – Corrected   – Patient with Hepatocellular Carcinoma (HCC)     • Better pathology visualization   – Corrected Images   – Subtracted Images – 2, 3 and 4 • REVEAL • Resolve Abdominal Imaging  Diffusion Imaging Techniques • 3D T1-weighted sequence • CAIPIRINHA - High iPAT Factors • DIXON – Fat/Water Separation • Multi-arterial phase imaging in a single breath-hold • Advantages   – High temporal resolution for multiple measurements with TWIST view-sharing   – Higher iPAT factors can be used with CAIPIRINHA Courtesy of Mount Sinai Med Hospital, New York, USA • Multi-arterial Phase Dynamic Sequence • Single Breath-hold • High Temporal and Spatial Resolution 2 Seconds 4 Seconds 7 Seconds 14 Seconds • Applications   – Dark Vessel Liver Imaging   – Single Shot EPI with Fat Suppression   – Low b-value Imaging     • b-value ≤50 s/mm2   – Increased lesion conspicuity   – Single Breath-hold   – Free Breathing – increased SNR b-value  = 50 s/mm2 • High Resolution • Increased SNR • Improved Image Sharpness • Combined  with iPAT   – Shortens EPI Echo Train Length (ETL) and effective Echo-spacing   – Reduced susceptibility and T2* decay artifacts • Diffusion Scheme   – Monopolar - Single Refocused Spin Echo Diffusion Encoding     • Shorter TE and increased SNR • b-Value   – Assign b-Value for each diffusion weighting • Averages   – Define number of averages per b-Value • ZoomIT   – Prerequisite: TimTX TrueShape • MapIT Body Imaging  New Techniques & Options • TimTX TrueShape   – Parallel Transmit (pTx) Technology   – Multi-channel TX Array Imaging   – Higher image quality   – Shorter scan time   – Focused and more homogeneous B1 Shimming • syngo ZOOMit   – Zoomed imaging   – Highlight regions and organs   – Reduced FoV   – Shorter Scan Time • ZoomIT Kidneys   – 30% high in-plane resolution for better differentiation of cortex and medulla • ZoomIT Prostate   – T2 TSE, matrix 384, GRAPPA 2, TA 3:36 min • Inline Parametric Map calculation   – T1, T2*, T2, R2* maps • Applications   – Liver   – Kidneys   – Prostate • R2* Map for Liver • Helps physician non-invasively assess relative stiffness of liver tissue   – 2D Gradient Echo with cyclic Motion-Encoding Gradients (MEG)     • Multi-slice capable with PACE     • iPAT – shortens breath-hold time     • Image Results       - Magnitude Image       - Relative Stiffness Map (Elastogram)       - Relative Stiffness 95% Map       - Wave Image       - Phase Difference Map       - Confidence Map Elastogram calculated from wave image Provides data about tissue stiffness • Hardware   – Active Driver   – Passive Driver   – Trigger Converter Box • Software   – Protocol – 2D Gradient Echo Active Driver Passive Driver Trigger Converter Box Magnitude Image Phase Difference Relative Stiffness Map Relative Stiffness 95% Map Wave Image Relative Stiffness Map (Elastogram) Wave Image Relative Stiffness Map (Elastogram) • System guided workflow to examine hepatic fat and iron status   – Prerequisite – Abdomen Dot Engine   – Consists of Three Sequences:     • T1 VIBE e-Dixon (First look) – single breath-hold (Whole Liver)     • T1 VIBE q-Dixon - Multi-echo Dixon VIBE     • HISTO – Breath-hold Single Voxel Spectroscopy (SVS) • Applications   – Single Shot EPI with Fat Suppression   – High b-value Imaging     • b-value range 50-1000 s/mm2     • b-values above 800 s/mm2 – normal tissue suppressed so high cellularity seen   – Single Breath-hold   – Free Breathing – increased SNR b-value  = 1000 s/mm2 ADC Map • Single breath-hold (Whole Liver)   – In and Opposed-phase, fat, water, water with segmentation and a report • Multi-echo Dixon VIBE • Images generated   – Water   – Fat   – Goodness of fit   – Fat Percentage   – R2*   – Water Percentage Maps • Breath-hold Single Voxel Spectroscopy (SVS)   – Voxel Location   – Report     • Fat Signal %     • R2 of water   – Spectrum with Shortest TE   – List of Individual Echo Values HISTO Result Table