director of body mri, pr ofessor of radiology university ...€¦ · • 32 y/o male with...
TRANSCRIPT
Advances in Gated MRA of the Thoracic Aorta Using Blood Pool
Agents
Jeffrey H. Maki, MD, PhD, FSCBTMR Director of Body MRI, Professor of Radiology
University of Washington, Seattle, WA
Disclosures – Jeffrey H. Maki
• Speaker’s Bureau Lantheus Medical • Research Support Bracco Diagnostics • Consultant Bayer Healthcare
• Will discuss “off label” use of
Gadofosveset (Ablavar) and Gadobenate (MultiHance)
Question #1 Does your practice perform
Blood Pool Imaging? 1. Yes, frequently 2. Occasionally, for specialized uses 3. No, but it seems intriguing … 4. No, because I don’t understand how
to do it 5. No, because I don’t really see any
benefit
Gd Blood Pool Agents
• Either bind albumin, or macro-aggregates • Contrast stays intravascular (vs. ECF) • Increased temporal window for imaging
- Higher resolution - ECG gating
• Single BP agent approved in USA (2008) = Gadofosveset Trisodium
- Ablavar - Lantheus - Initially “Vasovist” in EU – Bayer - Developmental name “MS-325” - EPIX
Gadofosveset • Linear Gd Chelate • Added side chain – 80-85% binding albumin • Increased relaxivity (r1 and r2)
- ~3-5x r1 of conventional Gd
• Increased intravascular residence - Intravascular t1/2 ~ 30 min
Gadolinium chelate
Diphenylcyclohexyl moiety
Phosphate diester bridge
Adapted from Leiner T et al, eds. Clinical Blood Pool MR Imaging.
ABLAVAR® [package insert]. North Billerica, MA: Lantheus Medical Imaging, Inc.; 2009.
MRA with BPA (Gadofosveset) • First pass –similar to conventional Gd
- Dose 0.03 mmol/kg (vs. standard 0.1 mmol/kg)
• Steady state - Begins ~2-5 minutes - Lasts > 30’ - Allows for greater resolution
• Useful for many MRA territories – e.g. peripheral • Venous imaging
- Allows for ECG triggering • Necessary to negate cardiac motion • T. Aorta (esp root) • Coronary arteries
- Allows for large volume coverage
Gadofosveset 0.03 mmol/kg
Elderly M w/claudication 3-station Runoff
First Pass
63-year-old male smoker – Suspected AIOD
Steady State Source Image - 1.0 x 0.9 x 0.9 mm resolution
Plaque easily seen
Axial Reformat
Gadofosveset 0.03 mmol/kg – Steady State (Blood Pool)
BP Agents T. Aorta • Early uses to aimed at coronary imaging
- “Whole Heart” coronary imaging
Kelle, Thouet, Tangcharoen, Nassenstin, Chiribiri, Paetsxh, Schnackernburg, Rarkhausen, Fleck, Nagel. Med Sci Monit. 2007 Nov;13(11):CR469-474.
Non-contrast Gadofosveset
Steady State Technique Adapted to Imaging Thoracic Aorta
• Naehle et al.+ 2009, University Bonn • Single dose gadofosveset • First pass and steady state – 25 pts • Congenital and acquired diseases thoracic
vasculature • Steady State – ECG gated, 3D IR, 6-8 min,
1.0 x 1.0 x 2.0 mm true resolution
+ Naehle, C. P., Müller, A., Willinek, W. A., Meyer, C., Hestermann, T., Gieseke, J., Schild, H., et al. (2009). First-pass and steady-state magnetic resonance angiography of the thoracic vasculature using gadofosveset trisodium. JMRI, 30(4), 809–816. doi:10.1002/jmri.21919
Naehle et al. - Aneurysm
Naehle, et al. JMRI, 30(4), 809–816. doi:10.1002/jmri.21919
First Pass Steady State
Naehle et al.
• First Pass – higher signal • Steady State – sharper, less
interobserver variability in diameter measurement
Naehle, et al. JMRI, 30(4), 809–816. doi:10.1002/jmri.21919
UW Practice • Many Cases of Aortic Pathology • Congenital
- Bicuspid AOV - Marfan’s - CHD
• Acquired - Aneurysm - Dissection
• Adapted Bonn technique to clinical practice
Example
• 32 y/o Male with Marfan’s • s/p Type A Dissection, Bentall and St. Jude • 0.04 mmol/kg gadofosveset
- 15 cc @ 1.0 cc/sec • 5 channel cardiac coil • 1.5T
First Pass Gadofosveset
1st Pass Vol Rend
1st Pass MIP
Steady State ECG-gated Gadofosveset Delayed Phase - Like Gated CT
Good (Best?) for accurate measurement aortic size
First Pass Steady State
Steady State ECG-gated Gadofosveset Delayed Phase - Looks like gated CT
Significant improvement in resolution ~ 1 x 1 x 1 mm
Source Images Obl Sag Axial MPR s
Example
• 21 y/o Male with chronic respiratory sx • Abnormal CXR • Suspicion of arch anomaly • 0.03 mmol/kg gadofosveset• 5 channel cardiac coil • 1.5T
Chest X-Ray Right Arch, ? Tracheal Narrowing
First Pass Ablavar MIP – Double Aortic Arch - Atretic left – Vascular Ring
Delay SS Ablavar Source Images Delay SS Ablavar Source Images
Delay SS Ablavar Source Images Delay SS Ablavar Axial Reformats
Delay SS Ablavar MIPs Double Aortic Arch Atretic left
Double Aortic Arch - Atretic Left 1st pass vs. gated SS
1st pass SS
1st pass
SS
Technique Useful
• Following up aortic disease • Serial measurements important
- Often done with Echo or CT • Acoustic window/angle problematic Echo • Radiation dose/motion with CT
• ECG-gating necessary, esp closer to root
- Non-gated CE-MRA blurred
Work 2010 – Ascending Aorta
Potthast, S., Mitsumori, L., Stanescu, L. A., Richardson, M. L., Branch, K., Dubinsky, T. J., & Maki, J. H. (2010). JMRI, 31(1), 177–184. doi:10.1002/jmri.22016
3D Nav Gated SSFP vs. CE-MRA
Also saw worse interobserver variability CE-MRA *Need ECG gating – esp close to root …
Example
• 15 y/o Male with ? Marfan s • Possible dilated Ao root by echo • 0.03 mmol/kg gadofosveset • 5 channel cardiac coil• 1.5T
Steady State ECG-gated Gadofosveset Mild Asc Ao Aneurysm
Steady State ECG-gated Gadofosveset Mild Asc Ao Aneurysm – STJ Effaced
First Pass Steady State
Steady State ECG-Gated Gadofosveset Mild Asc Ao Aneurysm – STJ Effaced
First Pass Nav SSFP Gadofosveset SS
Shown nav SSFP better than 1st pass Steady State ? better than nav SSFP … but need to do the study (as per coronary – more SNR; also – time efficient for large volumes)
Technique Simple • Easy free breathing add-on to CE-MRA • Requires cardiac package/ECG gating • Takes 5-8 minutes • Resolution sufficient for good reformats –
- Axial looks very “CTA”-like - More “approachable” to clinicians used to CT
• While standard Gd ECF agents not “blood pool”, they too can work (if fast)
- We have used gadobenate (MultiHance)
35 M s/p Ross Age 8, Replacement Asc AO w/reimplantion Coronary Arteries Age 28
30 mm Sinus of Valsalva Aneurysm
SS 5’ after 0.1 mmol/kg MultiHance
35 M s/p Ross Age 8, Replacement Asc AO w/reimplantion Coronary Arteries Age 28
30 mm Sinus of Valsalva Aneurysm
1st Pass CE-MRA SS 5’ after 0.1 mmol/kg MultiHance
35 M s/p Ross Age 8, Replacement Asc AO w/reimplantion Coronary Arteries Age 28
30 mm Sinus of Valsalva Aneurysm
1st Pass CE-MRA SS 5’ after 0.1 mmol/kg MultiHance
35 M s/p Ross Age 8, Replacement Asc AO w/reimplantion Coronary Arteries Age 28
Repeated Ablavar 6 mo later
SS 5’ after 0.1 mmol/kg MultiHance SS 5’ after 0.03 mmol/kg Ablavar
Question #2 Do you think Blood Pool Imaging
has a future in body MRA? 1. Yes, and we should be using it more 2. Yes, but it is a very “niche” imaging
technique only for experienced centers
3. No, it’s too complicated and/or expensive (time and $)
4. No, doesn’t add anything to what we already have
Conclusion (1/2) • Accurate and reproducible metrics of
the aorta are extremely important • ECG-gating essential
- Decreased blur - Less interobserver variability
• Blood pool agents an appealing solution
- Simple add on, especially if doing 1st pass MRA anyway
- Free breathing – greater resolution/detail
Conclusion (2/2)
• Our institution has seen good clinical success/acceptance SS MRA
- Implementing 90+% thoracic aortic MRA’s - > 100 cases to date
• Need studies to compare: - Nav SSFP vs. SS Blood Pool MRA - SS Blood Pool MRA gadofosveset vs. “other ECF”