Intratumoral Heterogeneous F-18 Fluorodeoxyglucose Uptake Corresponds with Glucose Transporter-1 and Ki-67 Expression in a Case of Krukenberg Tumor: Localization of Intratumoral Hypermetabolic Focus by Fused PET/MR Image

Abstract

The expression of glucose transporters (Glut-1, Glut-3), hexokinase-II, and Ki-67 has been proposed to explain intratumoral heterogeneous F-18 fluorodeoxyglucose (FDG) uptake. We report a case of Krukenberg tumor with intratumoral heterogeneous FDG uptake which corresponded well with the expression levels of Glut-1 and ki-67. Fused positron emission tomography (PET)/magnetic resonance (MR) imaging was helpful for localizing the metabolically active area in the tumor specimen. This report elucidates the relationship between the intratumoral heterogeneous FDG uptake and biologic heterogeneity, and shows the usefulness of PET/MR in research on intratumoral heterogeneity.

Keywords: FDG; Glut-1; Ki-67; Krukenberg tumor; PET/CT; PET/MRI.

Fig. 1

a T2-weighted coronal MR image showing a large right ovarian mass with a lobulated margin and heterogeneous signal intensity. b T2-weighted axial MR image showing a larger right ovarian mass (arrow) and a smaller left ovarian mass (arrowhead). c Contrast-enhanced fat-suppressed T1-weighted axial MR image showing heterogeneous enhancement of masses. d Axial fused FDG PET/CT image showing mild hypermetabolic tumor with the most metabolically active focus in the right anterior portion (arrow)

Fig. 2

a T2-weighted coronal MR image showing a large right ovarian mass with a lobulated margin and heterogeneous signal intensity. b Photograph of the same section shown in a showing its heterogeneous character. Five areas (MG1–MG5) of this tumor, including the metabolically active region (MG1, arrow) were selected for immunohistochemical studies. c Coronal PET image showing mild hypermetabolism on right ovarian mass with the most hypermetabolic focus on right lower portion (arrow). d Fused PET/MR coronal image revealing the anatomical location of the hypermetabolic focus, which lies in the right lower region of the mass (arrow)

Fig. 3

Glut-1 immunohistochemical staining of the five tumor areas (MG1–MG5) showing markedly increased cytoplasmic and membranous expressions of Glut-1 in the MG1 than in the other areas (original magnification, 200×)

Fig. 4

Ki-67 immunohistochemical staining of the five tumor areas (MG1–MG5) showing markedly increased expressions of Ki-67 in MG1 than in the other areas (original magnification, 200×)

Fig. 5

Correlation between SUVmax and immunoreactive level of Glut-1 (r ² = 0.99, P < 0.0001, a), labeling index of Ki-67 (r ² = 0.97, P = 0.002, b), immunoreactive level of hexokinase-II (P = n.s., c), and MVD (P = n.s., d). HK-II hexokinase-II