Emergency Abdominal MRI Protocols

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1 2018 SPR Annual Meeting & Postgraduate Course May 15-19, 2018 Nashville, Tennessee Emergency Abdominal MRI Protocols Unni Udayasankar MD Associate Professor Department of Medical Imaging University of Arizona College of Medicine

2 Acute Abdominal Pain in Children Acute abdominal pain is a common condition in the pediatric emergency rooms Most common surgical condition is acute appendicitis, most common nonsurgical condition is gastroenteritis The challenge for the physician is to identify children who have potentially life-threatening conditions that require urgent evaluation and treatment Imaging plays a crucial role

3 Acute Abdominal pain: Three distinct pathological groups Acute appendicitis Acute pelvic conditions (girls) Other acute intra-abdominal pathologies including Gastrointestinal Hepatobiliary-pancreatic Urinary

4 Suspected Acute Appendicitis: Unenhanced Rapid MRI protocol

5 CONTRAST??

6 Acute Appendicitis RAPID MRI PROTOCOL KEY SEQUENCES T2 SSFSE (ax + cor + sag) FS T2 SSFSE w SPAIR ADDITIONAL SEQUENCES T1 TSE w & w/o FS (ax) SSFP DWIBS SSFSE: Single Shot Fast Spin-Echo SPAIR: Spectral Adiabatic Inversion Recovery SSFP: Steady State Free Precession DWIBS: DWI with background body signal suppression (DWIBS)

7 T2 T2 T2 FS T2 FS T2 FS T2

8 Normal Appendix The normal appendiceal wall is relatively hypointense without surrounding inflammatory signal. A normal appendix is not usually fluid filled. The appendix is oftentimes best found by appropriately identifying the cecum, and identifying a blind ending tubular structure in the vicinity. It is unclear if previously described limit of 6mm can be applied to diameter of appendix on MRI. Wall thickness and periappendiceal inflammatory changes are better indicators of acute appendicitis on MRI. T2

9 Acute Appendicitis FS T2 T2 An 13 year old boy presented with two days of nausea and fever. The patient underwent an uncomplicated laparoscopic appendectomy. FS T2 T2 SPACE

10 FS T2 DWI Acute Appendicitis: DWI T2 ADC

11 Suspected Acute Pelvic Pathology Unenhanced MRI protocol

12 Acute (female) Pelvic Pathology RAPID MRI PROTOCOL SEQUENCES T2 SSFSE (ax + cor + sag) FS T2 SSFSE w SPAIR Ax DIXON: IP/OP FS T1 Ax Volumentric high res T2 DWIBS SSFSE: Single Shot Fast Spin-Echo SPAIR: Spectral Adiabatic Inversion Recovery SSFP: Steady State Free Precession DWIBS: DWI with background body signal suppression (DWIBS)

13 Axial T2 Axial T2 FS OVARIAN MASS AND TORSION: 14 year old with acute left ovarian torsion and bilateral paratubal cysts. Axial T2 weighted imaged show an enlarged and edematous left ovary with peripheral follicles. Also note bilateral paratubal cysts. Left ovarian stromal edema is better demonstrated on the fat suppressed T2 weighted image. Axial high resolution T2 weighted images also demonstrate the swirling sign of the left ovarian pedicle. Axial T2

14 Do we need three different protocols? Focused right lower quadrant abdomen and pelvis: Acute appendicitis Dedicated high resolution images of the pelvis: Pelvic pathology in girls General acute abdomen protocol Is it possible to have a protocol that covers all the pathologies?

15 Why should one strive for a single protocol Difficult to elicit classic clinical features in young children Overlap between acute pelvic pathologies and appendicitis in adolescent girls Potential protocol errors when studies are performed outside business hours Need for personnel to protocol

16 Crucial Sequence: Fat suppressed T2 Spectral Adiabatic Inversion Recovery or Spectral Attenuated Inversion Recovery STIR like contrast Insensitivity to B1 inhomogeneity (better for 3T) Consistently demonstrate improved and homogeneous fat suppression Increased contrast to noise ratio

17 Optimal fat suppression: Continuous table movement technique Uniform fat suppression is critical to accurately evaluate inflammatory changes in abdomen and pelvis Fat suppression efficacy is frequently reduced in multislice single shot T2 in anatomic regions away from magnet isocenter due to field inhomogeneity across imaging stack Continuous table movement technology allows improved image quality of fat suppressed techniques by allowing optimal slice homogeneity Reduced acquisition times

18 Moving towards a single protocol

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21 References Sharma P, Duke E, Bhattacharyya T, Kannengiesser S, Kalb B, and Martin DR. Comparative Analysis of Continuous Table and Fixed Table Acquisition Methods: Effects on Fat Suppression and Time Efficiency for Single-Shot T2- weighted Imaging. Joint Annual meeting ISMRM-ESMRMB. Milan, Italy. May2014 Lauenstein TC 1, Sharma P, Hughes T, Heberlein K, Tudorascu D, Martin DR. Evaluation of optimized inversion-recovery fat-suppression techniques for T2-weighted abdominal MR imaging. J Magn Reson Imaging Jun;27(6):