11C-methionine uptake correlates with combined 1p and 19q loss of heterozygosity in oligodendroglial tumors

Abstract

Background and purpose: Oligodendroglial tumors with 1p/19q LOH are known to show longer patient survival than those without 1p/19q LOH, but the reason for this clinical difference has not been elucidated, to our knowledge. This study was designed to clarify whether uptake of MET correlates with 1p/19q LOH of oligodendroglial tumors.

Materials and methods: This study included 102 consecutive patients with supratentorial WHO grade II and III oligodendroglial tumors (39 oligoastrocytic and 63 oligodendroglial tumors) that were resected and diagnosed between January 2008 and August 2011 at Tokyo Women's Medical University Hospital. These patients underwent MET PET T/N ratio measurement before treatment. T/N ratios were calculated by dividing the maximum SUV for the tumor by the mean SUV of the contralateral normal frontal cortex. After surgery, FISH for resected tissues was used to determine 1p/19q LOH.

Results: The mean T/N ratio of tumors with 1p/19q LOH was significantly greater than that of tumors without 1p/19q LOH (P = .0166). The threshold T/N ratio value of 2.46 was found to correlate significantly with 1p/19q LOH by univariate (P = .0011) and multivariate analyses (P = .0209) in all tumors.

Conclusions: The T/N ratio on MET PET might be a useful aid to the diagnosis of 1p/19q LOH. Our data add new information on the biology and imaging characteristics of oligodendroglial tumors with 1p/19q LOH.

Fig 1.

A, Boxplots of T/N ratio values for grade II and III tumors. B, Boxplots of T/N ratio values for 1p/19q LOH–positive and –negative tumors in all tumors. C, Boxplots of T/N ratio values for 1p/19q LOH–positive and –negative in grade II tumors. D, Boxplots of T/N ratio values for 1p/19q LOH–positive and –negative in grade III tumors. Yes indicates 1p/19q LOH–positive; No, 1p/19q LOH–negative.

Fig 2.

A–C, A representative 1p/19q LOH–negative oligodendroglioma. A, CT image shows a left insular tumor without calcification. B, T2-weighted MR image shows the high-intensity tumor in the insula. C, T2-weighted MR image coregistered with the MET PET image shows the T/N ratio value to be 1.47. D–F, A representative 1p/19q LOH–positive oligoastrocytoma. D, CT scan shows a right frontal tumor with calcification. E, T2-weighted MR image shows the high-intensity tumor in the right frontal lobe. F, T2-weighted MR image coregistered with the MET PET image shows the T/N ratio value to be 3.66.

Fig 3.

A–C, A representative 1p/19q LOH–negative anaplastic oligodendroglioma. A, CT scan shows a left frontal tumor without calcification. B, T2-weighted MR image shows the high-intensity tumor in the left frontal lobe. C, T2-weighted MR image coegistered with the MET PET image shows the T/N ratio value to be 1.39. D–F, A representative 1p/19q LOH–positive anaplastic oligoastrocytoma. D, CT scan shows a left frontal tumor with calcification. E, T2-weighted MR image shows the high-intensity tumor in the left frontal lobe. F, T2-weighted MR image coregistered with the MET PET image shows the T/N ratio value to be 5.94.