Perforator MR Angiography Martin R. Prince Cornell and Columbia Medical Centers

Transcription

1 Perforator MR Angiography Martin R. Prince Cornell and Columbia Medical Centers MRI Fellows Nanda Thimmappa Mukta Agrawal Silvina Dutruel Tiffany Newman Sri Boddu Plastic Surgeons Joshua L Levine Julie Vasile David Greenspun Constance Chen Christina Rhode Christina Y Ahn Robert Allen

2 Disclosure: Patent agreements with Mallinckrodt Bayer Bracco Lantheus Epix Medrad Nemoto Topspins GE Siemens Philips Toshiba Hitachi

3 Learning Objectives 1. How to image perforator vessels for autologous breast reconstruction. 2. Review anatomic and surgical considerations for selecting optimum perforator vessels 3. Review perforator findings from a spectrum of cases. 4. See a systematic approach to post-processing and reporting perforator studies.

4 Breast Cancer 14% of Women Autologous flap breast reconstruction is increasingly popular. TRAM Transverse Rectus Abdominus Myocutaneous Flap Long abdominal healing times Post-op abdominal complications - hernia DIEP Deep Inferior Epigastric Perforator Flap Faster recovery time Less abdominal complications More complicated perforating vessels dissected through muscle TRAM DIEP

5 Posterior Thigh Flap

6 Cornell MRA DIEP Technique: Scanner 1.5T less artifact with large FOV Patient position Prone Contrast Gadofosveset Trisodium (blood pool) Sequences Ax/Cor SSFSE T2, Ax LAVA flex, Sag/Cor SPGR post Gd Key sequence 3D 2-echo SPGR Dixon fat-water separation (LAVA flex) TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm reconstructed at 1.5mm i.e. ZIP2. Matrix 512x512 4 minutes Band width 125 khz Field of view Phase encoding Right to left eliminates bowel peristalsis artifact Coverage All graft harvest site

7 Position: Prone Motion artifact in phase direction

8 Cornell MRA Technique: Scanner 1.5T less artifact with large FOV Patient position Prone Contrast Gadofosveset Trisodium (blood pool) Sequences Ax/Cor SSFSE T2, Ax LAVA flex, Sag/Cor SPGR post Gd Key sequence 3D 2-echo SPGR Dixon fat-water separation (LAVA flex) TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm reconstructed at 1.5mm i.e. ZIP2. Matrix 512x512 4 minutes Band width 125 khz Field of view Phase encoding Right to left eliminates bowel peristalsis artifact Coverage All graft harvest site

9 Cornell MRA Technique: Scanner 1.5T less artifact with large FOV Patient position Prone Contrast Gadofosveset Trisodium (blood pool) Sequences Ax/Cor SSFSE T2, Ax LAVA flex, Sag/Cor SPGR post Gd Key sequence 3D 2-echo SPGR Dixon fat-water separation (LAVA flex) TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm reconstructed at 1.5mm i.e. ZIP2. Matrix 512x512 4 minutes Band width 125 khz Field of view Phase encoding Right to left eliminates bowel peristalsis artifact Coverage All graft harvest site

10 Gadofosveset trisodium JMRI 2012; 35(3): Reversibly binds to albumin with 90% binding fraction Redistribution half life =28 minutes 5 6-fold greater T1 relaxivity at 1.5 T vessel-to-fat contrast ratio similar to gadobenate vessel-to-muscle contrast ratio significantly higher Vessel to Muscle contrast Vessel to Fat contrast

11 MRA Technique: Scanner GE Signa 15.0/14.0, Milwaukee, WI Patient position Prone Contrast Gadofosveset Trisodium Sequences Ax/Cor SSFSE, Axial pre, dynamic and post contrast SPGR Key sequence HR Liver Acquisition with Volume Acceleration(LAVA) Imaging plane Axial TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm recon at 1.5mm. Matrix 512x512 Band width 125 Field of view Phase Right to left Coverage Based on graft harvest site

12 ccult metastases 4% (5/120)* *ISMRM Thimmappa 2013

13 MRA Technique: Scanner GE Signa 15.0/14.0, Milwaukee, WI Patient position Prone Contrast Gadofosveset Trisodium Sequences Ax/Cor SSFSE, Axial pre, dynamic and post contrast SPGR Key sequence HR Liver Acquisition with Volume Acceleration(LAVA) Imaging plane Axial TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm reconstructed at 1.5mm with zero filling Matrix 512x512 Band width 125 Field of view 36-48cm Phase encoding Right to left Coverage Based on graft harvest site

14 MRA Technique: Scanner GE Signa 15.0/14.0, Milwaukee, WI Patient position Prone Contrast Gadofosveset Trisodium Sequences Ax/Cor SSFSE, Axial pre, dynamic and post contrast SPGR Key sequence HR Liver Acquisition with Volume Acceleration(LAVA) Imaging plane Axial TR/TE 4/1.9 Flip angle 15 Slice thickness 3mm recon at 1.5mm. Matrix 512x512 Band width 125 Field of view Phase Right to left Coverage Based on graft harvest site

15 Phase: Right-Left Phase: A-P

16 Calculating perforator coordinates Axial HR LAVA (R 5.4, S32.8) From facial attachment of umbilicus. From point where vessel exits rectus sheath to enter subcutaneous tissue (R 64, I 25.6) Axial HR LAVA Umbilicus R1 3D volume rendered

17 Calculating vessel diameter

18 Intramuscular Course Para-muscular (septo-cutaneous)

19 Calculating fat volume and fat thickness Manual tracing 13cm 40cm

20 Sample Report : Important Points to be reported Coordinates with respect to landmark Intramuscular course and distance Vessel diameter Fat volume measurement

21 Type 1 DIEA Type 2 DIEA Type 3 DIEA

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23 Superficial Inferior Epigastric artery variations DIEA a b c

24 Superficial Inferior Epigastric Veins

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26 Gluteus: SGAP, IGAP Landmark: Top of gluteal crease Position: Prone Coverage: 5cm above marker to below inferior buttock crease

27 SGAP and IGAP Perforators 1. Patency of SGA and IGA 2. Coordinates with respect to landmark 3. Vessel diameter 4. Intramuscular course and distance 5. Subcutaneous fat thickness

28 SGAP and IGAP Perforators Transverse coordinates are calculated with respect to midline by tracing along skin surface.

29 Posterior Thigh Flap Landmark: Inferior gluteal crease Position: Prone Coverage: mid gluteal region to 12cm below the inferior gluteal crease

30 TUG Flap Landmark: Pubic symphysis Position: Supine Coverage: Pubic symphysis to 15cm below it.

31 Transverse Upper Gracilis Flap

32 Thoraco Dorsal Artery: TDA Flap Landmark: Sternal notch Position: Supine Coverage: sternal notch to xiphoid process

33 Lateral thoracic: TDA Flap

34 Lumbar flap Landmark: Iliac crest Position: Supine Coverage: Umbilicus to mid gluteal region

35 Lumbar Perforator Axial HR LAVA 1. Coordinates with respect to landmark 2. Vessel diameter 3. Intramuscular course and distance 4. Subcutaneous fat thickness

36 Tissue Expanders: Are they MR safe? Pectoralis Muscle Subcutaneous Fat Skin Injection port Chest wall Tissue Expander Thimmappa N et al, Breast Tissue Expanders with Magnetic Ports: In Vitro Testing and Clinical Experience at 1.5-Tesla. Presented at ISMRM 2013

37 Summary of Key Points CTA requires bolus timing intramuscular course not well seen MRA blood pool contrast: gadofosveset 10ml 512 x 512 matrix Prone positioning to minimize respiratory motion Phase encoding R-L to avoid peristalsis artifacts Report Coordinates of best perforators Label perforators from top to bottom L1, L2, L3 Diameter MIP of intramuscular course DIEP patency and arborization pattern Alternative sites: PAP, SGAP, IGAP, TUG, TDA, LDAP

38 Surgeons feedback: Ms X had Bilateral DIEP, R1 septocut; L2 septocut. Same perforator used as planned. On L2, intraop was found to have a branch just under the fascia so both branches of L2 was used. No discrepancy in location. The MR was crucial in this patient because R1 was close to the midline and very close to the umbilical stalk. if I didn't know this ahead of time, there is a good chance that I would have cut right through it, and that was the best perforator on that side of the abdomen. in fact, the mr didn't show any other sizeable perforators on that side. I did shift the midline division of the flap slightly towards the left since I knew that R1 was close to the midline so as to preserve more arborization. - Julie Vasile, MD Plastic and reconstructive surgery, New York Ms Z Bilat DIEP R3 L2 intramuscular. Same used as planned. No discrepancy location. MR was so helpful because it showed that L2 was the most tortuous perforator that I've encountered. It was very helpful to know this ahead of time because the course was so anomalous, and may have lead me to cut the main perforator, mistaking it for a branch to the muscle. In addition, it was nice to know that I was in for a long intramuscular dissection ahead of time. Flap design was not shifted. - Joshua Levine MD Plastic and reconstructive surgery, New York

39 Pre operative imaging Comparison of the various tools for preoperative imaging Nahabedian M, Clin Plastic Surg 38(2011)

40 Common types of Skin islands Superior Gluteal Artery Perforator flap Posterior Artery Perforator flap Superficial Inferior Epigastric artery Perforator flap Inferior Gluteal Artery Perforator flap

41 Automated Reporting System:96 cases Reporting template options Intramuscular distance measuring tools Flap volume quantification Tables of perforator flap artery information (coordinates, diameters, intramuscular descriptions and distance) Additional functions An automated reporting system implemented in xcode/cocoa as an Osirix plugin using objective-c language streamlined workflow issues and reduced manual data entry errors. Of the 27 reports created manually, 3 (10%) had manual entry errors that were rectified before surgery. Such errors were not seen in any automated reporting system case. Report generated takes 18 min vs 56 min with manual reporting (p<0.001).

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43 Recent advances

44 Spiral imaging for SIEA For pure arterial phase images, e.g. SIEA visualization or to rule out TDA/IMA stenosis, a spiral k- space trajectory LAVA reconstructed at 3sec temporal resolution allowed flexibility to find the moment of maximal arterial enhancement before venous contamination.

45 Coronal spiral for IMA/IMV

46 Dixon fat-water separation (Lava flex) at 3T Lava Flex at 3T Ax HR Lava at 1.5T We have also noticed superior quality using a 2 point Dixon method for fat/water signal separation (Lava flex, GE).