Lung Cancer

PD 16 - Lung 4 - Poster Discussion

1139 - Late Gadolinium Enhancement (LGE) in Cardiac Magnetic Resonance Imaging (CMR)

Wednesday, October 24
11:24 AM - 11:30 AM
Location: Room 217 C/D

Late Gadolinium Enhancement (LGE) in Cardiac Magnetic Resonance Imaging (CMR)
A. Ricco, J. Canada, J. Grizzard, F. Dana, L. Rezai Gharai, K. Neiderer, A. Vera, A. Abbate, and E. Weiss; Virginia Commonwealth University, Richmond, VA

Purpose/Objective(s): Mechanisms of radiation-induced cardiac toxicity are not well understood and are currently being investigated. In this proof-of-concept study, we hypothesize that regions of high radiation dose in the myocardium correlate with late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR), which is a marker of myocardial damage.

Materials/Methods: 28 patients without cardiac history with chest tumors treated with radiation therapy and a heart dose V5Gy ≥ 10% underwent CMRs on a cross sectional study protocol. The volume of LGE was delineated in conjunction with board certified radiologists who were blinded to the dose distribution. Three-dimensional rigid registrations of the left ventricles were performed fusing CMR to the computed tomography (CT) planning scans used for dosimetric calculations. Dosimetric analysis was undertaken to explore if a dose-response relationship exists between radiation therapy plans and areas of LGE.

Results: Patients had a mean age of 62 years (range 28-87) and included 14 primary lung cancers, 9 breast, 2 esophageal, 1 lymphoma, and 2 other tumors. The median time from end of radiation treatment to CMR was 23.2 months (range 1.7-349.3). In total 9 patients showed LGE within the left ventricular wall or septum with a mean volume of 2.29cc (range 0.24-6.06). Among the 9 patients with LGE, the max and mean dose to the heart was on average 56.2Gy (21.8-80.4) and 10.0Gy (3.29-29.28), respectively, as compared to 19 patients without LGE, where the max and mean dose to heart was on average 44.2Gy (10.3-78.1) and 11.8Gy (1.9-42.0), respectively. There was no significant difference in max or mean heart dose between both groups (p=0.07 and p=0.74). The max and mean dose to the LGE volume itself was 17.19Gy (0.92-32.9) and 10.49Gy (0.73-23.7), respectively. The location of max heart dose was located outside the contoured LGE volume in all 9 patients. There was no association between max and mean dose in the LGE area and size of the LGE volume (p=0.84 and p=0.36, respectively).

Conclusion: In this pilot study of patients who underwent radiation therapy to the thorax, no dose-response relationship was identified for LGE on CMR. Locations of myocardial fibrosis and tissue remodeling following radiation treatment may not occur in high dose regions of radiation treatment plans. Newer CMR methods of detection and localization of myocardial fibrosis such as T1-mapping will be explored in future studies to ascertain their relevance to radiation-induced cardiac toxicity.

Author Disclosure: A. Ricco: None. J. Canada: None. J. Grizzard: None. F. Dana: None. L. Rezai Gharai: None. E. Weiss: Royalties; UpToDate, NIH, Varian Medical Systems.

Anthony Ricco, MD

Disclosure:
No relationships to disclose.

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