How to Deliver Suitable MR and CT Data for Catheterization Overlay

Jason N. Johnson MD MHS

Director, Cardiac MRIAssociate Professor of Pediatrics and RadiologyUniversity of Tennessee Health Sciences Center

Le Bonheur Children’s HospitalSt. Jude Children’s Research Hospital

jjohn315@uthsc.edu

Disclosure Statement

• Consultant for Abbott

Outline

• Imaging acquisition– MR– CT

• Segmentation• Registration• Visualization

Not all examples tetralogy of Fallot

RoadmappingDevice

positioning

Radiation reduction

Utility of MR Fusion

InterventionalPlanning

Camera angleselection

Multimodality Fusion - Workflow

MRI / CT acquisition

Registration to Fluoro

Visualization

IMAGE ACQUISITION

Time-resolved angiography (TWIST, TRICKS, TRAK, Freeze Frame)

3D MRA technique with very high temporal (sub-second) resolution which will allow to capture the arterial,

mixed and venous phase images during the passage of a contrast agent through the vascular anatomy

✔ Good temporal resolution (sub-second) allows for separating right and left side

✖ Not gated

✖ Lower spatial resolution (sub-millimeter)

MRI acquisition Registration Visualization

MRA Acquisition

Parameter: TR 3 ms, TE 1 ms, flip angle 25FOV 250-400 mm, isotropic voxel -1.0 mm

Left Right

MRI acquisition Registration Visualization

MRA AcquisitionBolus Triggered 3D MRA (Care Bolus, SmartPrep, BolusTrak, Visual Prep)

✓ Good temporal and spatial resolution ✓ Focus region of interest without losing critical information✓ Gadolinium: 0.15 mmol/kg (0.3 ml/kg) @1.5 ml/sec✓ ✖ Breath hold✓ ✖ ECG gated

Parameter: TR 3.5 ms, TE 1.3 ms, flip angle 30FOV 250-400 mm, isotropic voxel -1.0 mm

Navigator gated 3D GRE sequence:

✓ High spatial but lower temporal resolution

✓ ECG (systole, diastole, or both) and respiration gated

✓ Useful for real time MRI guided procedures

✖Hard to separate right and left side

MRI acquisition Registration Visualization

MRA Acquisition

Isotropic voxels of 1.0 to 1.3 mm, TE 1.6 msec, TI 260 msec, and flip angle of 18 degrees. Whitehead KK, et al. J Cardiovasc Magn Resonan. 2014;16:P109.

CTA acquisition Registration Visualization

CTA AcquisitionCT Angiography with contrast

✓ Excellent temporal and spatial resolution ✓ Quick acquisition with minimal radiation*✓ Contrast: Isovue 300 ~ 2 ml/kg @ 3 ml/sec✓ Breath hold✓ ✖ ECG gated

Parameter: Slice thickness 0.5 mm, kVP 100, rotation time 0.35 s, pitch 0.813, CTDI 2.7 mGy

3D Rotational Angiogram

Rotational Angio Registration Visualization

✓ Excellent temporal and spatial resolution

✓ Quick acquisition with radiation exposure

✓ ContrastX Requires pacingX Different catheters required to

see multiple structures

Segmentation

CTA Segmentation

Smooth Hollow

CTA Segmentation

3DRA Reconstruction

Registration

2D / 3D Visual Matching RegistrationAP Lateral

MRI acquisition Registration Visualization

Registration – Internal Markers

MRI acquisition Registration Visualization

Registration – Internal Markers

CTA acquisition Registration Visualization

Ribs

Sternum

Spine

Registration – Internal Markers

Rotational Angio Registration Visualization

Surgical Clips

Sternal Wires

Tubes

Aligned

Registration – Internal Markers

MRI acquisition Registration Visualization

Valve Marker

LPA Stent

Registration – External Markers

MRI acquisition Registration Visualization

Vitamin E Capsule –Radiopaque Marker

Visualization

Fusion Visualization

Rotational Angio Registration Visualization

CMR Registration / Visualization

MRI acquisition Registration Visualization

CTA Registration / Visualization

CTA acquisition Registration Visualization

Registration / Visualization LimitationsMisaligned

Sternal Wires

Surgical Clip Sternal Wires

Tubes

Rotational Angio Registration Visualization

Case Utilization

HLHS status post GlennSevere TRResidual arch obstruction

Case Utilization

Le Bonheur Experience

Variable3DRA-Fusion

(n=25)

MR-Fusion

(n=25)

CT-Fusion

(n=25)P-Value

Radiation (min) 21.8 ± 12.2 18 ± 9.7 19.4 ± 10.4 0.04

# of angiography 7.2 ± 3.8 5.4 ± 4.7 6.8 ± 3.6 0.52

Dose-Area (cGy.cm2) 4101 ± 1382 2454 ± 1113 5607 ± 2465 0.01

Air Kerma (mGy) 654 ± 224 499 ± 189 806 ± 328 0.01

Contrast (mL/Kg) 4.9 ± 3.1 2.7 ± 2.4 5.9 ± 3.8 <0.001

Procedure (min) 214 ± 93 163 ± 38 167 ± 42 0.03

Anesthesia time (min) 258 ± 112 384 ± 174 213 ± 98 <0.001

Conclusions

MRI / CT acquisition

Registration to Fluoro

Visualization

References• Dori Y, Sarmiento M, Glatz AC, Gillespie MJ, Jones VM, Harris MA, Whitehead KK,

Fogel MA, Rome JJ. X-ray magnetic resonance fusion to internal markers and utility in congenital heart disease catheterization. Circ Cardiovasc Imaging. 2011;4:415-424.

• Glöckler M, Halbfaβ J, Koch A, Achenbach S, Dittrich S. Multimodality 3D-Roadmap for cardiovascular interventions in congenital heart disease – A single-center, retrospective analysis of 78 cases. Cathet Cardiov Interv. 2013;82:436-442.

• Goreczny S, Dryzek P, Moszura T. Novel 3-dimensional image fusion software for live guidance of percutaneous pulmonary valve implantation. Circ CardiovascInterv. 2016;9:e003711.

• Whitehead KK, Harris MA, McNeal GR, Fogel MA. Use of a 3D respiratory navigated IR-FLASH sequence after gadofosveset in the pediatric adult congenital population. J Cardiovasc Magn Resonan. 2014;16:P109.

Thank YouLe Bonheur Children’s

Hospital

Cardiac Catheterization TeamShyam Sathanandam, MDRush Waller, MDHitesh Agrawal, MD

Cardiovascular Magnetic Resonance Team

Anthony Merlocco, MDCara Morin, MD PhDRonak Naik, MDGovinda Paudel, MD