RSNA 2014 

Abstract Archives of the RSNA, 2014


MIS135

MR Imaging of Tumor Associated Macrophages In Pediatric Patients with Malignant Lymphomas and Sarcomas

Scientific Posters

Presented on December 2, 2014
Presented as part of MIS-TUB: Molecular Imaging Tuesday Poster Discussions

Participants

Tarsheen Sethi MBBS, Presenter: Nothing to Disclose
Jessica Donig BA, Abstract Co-Author: Nothing to Disclose
Maryam Aghighi MD, Abstract Co-Author: Nothing to Disclose
Samantha Holdsworth PhD, Abstract Co-Author: Nothing to Disclose
DITA GRATZINGER, Abstract Co-Author: Nothing to Disclose
Heike E. Daldrup-Link MD, Abstract Co-Author: Nothing to Disclose
Florette Hazard, Abstract Co-Author: Nothing to Disclose
Raffi S. Avedian MD, Abstract Co-Author: Nothing to Disclose
Neyssa Marina MD, Abstract Co-Author: Nothing to Disclose
sandra luna-fineman MD, Abstract Co-Author: Nothing to Disclose

PURPOSE

Tumor associated macrophages (TAM) are key components of the tumor microenvironment with a role in the pathogenesis and progression of many tumors. The aim of our study was the clinical translation of a non-invasive technique for imaging TAMs in pediatric tumors based on ferumoxytol-enhanced Magnetic Resonance (MR) Scans, evaluating iron uptake as surrogate for macrophage content and correlating with histopathology. 

METHOD AND MATERIALS

15 children and young adults with lymphomas (n=7) and sarcomas (n=8) underwent MR imaging at least 24 hours after intravenous injection of the iron oxide nanoparticle ferumoxytol. MR scans included STIR and T1-weighted SPGR sequences for anatomical assessment of iron uptake and T2* FSPGR and eFGRE sequences for quantitative assessment. Mean T2*-relaxation times of whole tumors were calculated. In addition, tumor regions with intracellular and extracellular iron were differentiated based on STIR and T1-weighted SPGR MR Scans. Histopathology correlation was based on 11 biopsy and 3 tumor resection samples evaluated by Prussian blue stain and macrophage immunohistochemistry markers CD-68 and CD-163. Macrophage content was assessed semi-quantitatively as low, intermediate and strong CD68 and CD163 staining by manual slide review by two pathologists. T2*-relaxation times of whole tumors and tumor areas were correlated with macrophage quantities on histopathology. Tumor macrophage heterogeneity was also assessed on MR Scans and compared with histopathology using McNemar’s test. 

RESULTS

The mean T2* relaxation times were 4.53 ms and 6.15 ms for sarcomas and lymphomas respectively. All tumors demonstrated presence of macrophages by immunohistochemistry. Sarcomas showed a heterogeneous distribution of TAM on pathologic evaluation and heterogeneous iron uptake on MR scans, while six out of seven lymphomas showed homogenous TAM distribution and iron uptake. A McNemar’s test revealed no significant difference in assessment of homogenous or heterogenous TAM distribution by histology or imaging (p value =1.00).

CONCLUSION

Our study represents the clinical translation of a non-invasive method for TAM imaging based on ferumoxytol enhanced- MR scans with histopathology correlation. 

CLINICAL RELEVANCE/APPLICATION

The presented ferumoxytol enhanced-MR based technique is immediately clinically applicable and allows for a non-invasive imaging of TAM, a potential marker for prognosis and immunotherapy response assessment.

Cite This Abstract

Sethi, T, Donig, J, Aghighi, M, Holdsworth, S, GRATZINGER, D, Daldrup-Link, H, Hazard, F, Avedian, R, Marina, N, luna-fineman, s, MR Imaging of Tumor Associated Macrophages In Pediatric Patients with Malignant Lymphomas and Sarcomas.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017371.html