(P 235) FUSION OF PREOPERATIVE IN SITU MAGNETIC RESONANCE IMAGING AND POSTOPERATIVE COMPUTED TOMOGRAPHY TO CORRELATE FUNCTIONAL IMAGING FEATURES AND PATHOLOGICAL CHARACTERISTICS OF SOFT TISSUE SARCOMA

Location: The Liffey, Level 1

Author(s)

Madelaine Hettler, MD (she/her/hers)

PhD Student
Department of Surgery, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
Mannheim, Baden-Wurttemberg, Germany

Co-Author(s)

JK

Julia Kitz, MD

Institute of Pathology, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
AS

Ali Seif A. H., MD

Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
MG

Manuel Guhlich, MD

Department of Radiotherapy and Radiation Oncology, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
BP

Babak Panahi, MD

Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
JE

Jennifer Ernst, MD

Department of Trauma Surgery, University Medical Center Hannover, 30625 Hannover,Germany
Hannover, Niedersachsen, Germany
LC

Lena-Christin Conradi, MD

Department of General, Visceral and Pediatric Surgery, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
MG

Michael Ghadimi, MD

Department of General, Visceral and Pediatric Surgery, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
PS

Philipp Ströbel, MD

Department of General, Visceral and Pediatric Surgery, University Medical Center Goettingen, 37075 Goettingen, Germany
Göttingen, Niedersachsen, Germany
Jens Jakob, MD (he/him/his)

Prof.,
University Medical Center Mannheim, University of Heidelberg
Mannheim, Baden-Wurttemberg, Germany

Objective: Treatment and prognosis of soft tissue sarcoma (STS) are primarily based on histological subtype and grading. However, due to tumor size and intratumoral heterogeneity, pretherapeutic biopsies often do not provide reliable tumor characterization. By correlating functional imaging and histopathologic features, pretreatment grading might be improved.

Methods: Twelve patients with histologically confirmed STS were included in the prospective pilot study. A diffusion weighted MRI was performed preoperatively. After tumor resection, core needle biopsies (CNBs) from distinct tumor sites from the surgical specimen were collected and a radiopaque marker was left at each biopsy site. Afterwards, a CT of the specimen visualized the markers. Fusion imaging of preoperative in situ MRI and postoperative CT was sought to evaluate the imaging characteristics of the exact sampling regions (Figure 1). The apparent diffusion coefficient (ADC) on functional MRI and histopathological grading according to Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) criteria were determined for all specimens and CNBs.

Results: Fusion imaging of pretreatment MRI and postoperative CT of the resected specimen was feasible in 7/12 cases without relevant contour discrepancies. Histological workup resulted in correct grading in 9/11 cases (81,8 %, in n=2: G1 instead of G2). Analysis of multiple tumor biopsies verified the expected intratumoral heterogeneity. Functional evaluation showed a tendency for high-grade regions (G2/G3; median (range) ± standard deviation: 1.13 (0.78–1.70) ± 0.23 × 10−3 mm2/s) to have lower ADC values than low-grade regions (G1; 1.43 (0.64–2.03) ± 0.46 × 10−3 mm2/s).

Conclusion: Our pilot study demonstrates the technical feasibility of correlating imaging features of preoperative in situ MRI and postoperative CT of the specimen by fusion imaging. In this regard, ADC appears to correlate with the FNCLCC grading criteria. Further studies are necessary to clarify the potential of functional imaging to supplement histopathological grading.