Interventional Applications

1355167 - Assessing the Potential for Guided Endomyocardial Biopsy in Pediatric Heart Transplant Patients Using T1 and T2 Hotspot Locations

Wednesday, January 25, 2023

Location: E-POSTER

Presenting Author(s)

VC

Vincent Cleveland, MSc, MPH

Dev/Ops Engineeer
Children's National Medical Center
Washington, District of Columbia, United States

Co-Author(s)

JC

Jacqueline Contento, BSE

Research Engineer
Children's National Hospital, District of Columbia, United States
DR

Devika P. Richmann, MD

Pediatric Cardiology Fellow
Columbia—Morgan Stanley Children’s Hospital of New York, United States
MU

Michelle Udine, MD

Advance Imaging Cardiologist
Children's National Medical Center, United States
RC

Russell R. Cross, MD

Director, Cardiac MRI
Children's National Hospital
Washington, District of Columbia, United States
JK

Joshua Kanter, MD

Medical Director of Interventional Cardiology
Children's National Hospital
Washington, District of Columbia, United States

Primary Author(s)

Laura Olivieri, MD

Director, Noninvasive Cardiac Imaging
Children's Hospital of Pittsburgh of UPMC, United States

Background: Endomyocardial biopsy (EMB) is an essential tool for assessing the rejection status of patients who have undergone heart transplantation. Unfortunately, the current strategy of blind sampling the right ventricular myocardium can produce false negative EMB results.¹^,² T1 and T2 parametric mapping may identify potential sites of cellular rejection in these patients.³ Regions of T1 and T2 elevation, known as “hotspots,” can offer a target for guided EMB procedures, which may in turn minimize false negative biopsy results and more reliably guide therapy. Through overlay of magnetic resonance images onto fluoroscopic guidance, clinicians can perform guided biopsies in this patient population.⁴ However, only a limited portion of the myocardium is available for EMB. Therefore, we sought to understand the incidence and dispersion of T1 and T2 elevations in a pediatric heart transplant population to determine how many T1/T2 hotspots would be “biopsiable” and how many were successfully biopsied at our institution.

Methods:

With consent/assent, 34 pediatric orthotopic heart transplant patients underwent non-contrast cardiac magnetic resonance (MR) imaging on a 1.5T magnet with breath-held T1 and T2 mapping in eight short-axis slices immediately prior to their clinically-indicated EMB procedure. If present, regions of T1 and T2 elevation were segmented using standard approach (ITK-SNAP, v3.6) and overlaid onto bi-plane fluoroscopy during their EMB procedure. The accessibility of the right ventricular regions using EMB technique with a steerable sheath (Oscor) was determined a priori, based on location in the septum and ability to avoid free wall and tricuspid valve.

Results: Comprehensive T1 and T2 mapping yielded 120 total hotspots in 75 imaging+EMB procedures, including 86 (72%) T1 hotspots and 34 (28%) T2 hotspots, with no imaging or hotspot segmentation failures. Nine (12%) of the scans had no hotspots, 31 (41%) had one hotspot, 20 (27%) had two hotspots, and 15 (20%) had >2 hotspots. Of the 120 hotspots, 54 (45%) were in regions of the heart deemed accessible for biopsy (basal and mid septal, remote from the tricuspid valve) and 17 (14%) of hotspots were successfully biopsied within 10 mm of the hotspot edge mainly in segments 8 (anterior septal) and 14 (apical septal).

Conclusion: Cardiac MR data offers feasible and comprehensive myocardial assessment for T1 and T2 abnormalities in transplant patients, which may be used as a roadmap to guide EMB. CMR identified regions of T1/T2 elevation that were successfully biopsied only ~13% of the time due to requirements of RV EMB procedure. Future work should be focused on understanding the value of T1 and T2 hotspots in identifying active rejection requiring therapy.