Histological growth patterns and genotype in oligodendroglial tumours: correlation with MRI features

Abstract

Oligodendroglial neoplasms with the -1p/-19q genotype are more indolent with longer survival and increased therapeutic responsiveness than those with intact 1p/19q, but the biological basis for these clinical differences is unclear. Recent research suggests that oligodendrogliomas with and without the -1p/-19q genotype may be distinguished by their magnetic resonance imaging (MRI) appearance, suggesting possible differences in growth characteristics. This study examined the relationship between genotype and histological growth patterns of oligodendroglial neoplasms in association with MR imaging characteristics. Tumour imaging features assessed on MRI included sharp-versus-indistinct border, smooth-versus-irregular contour, homogeneous-versus-heterogeneous signal, contrast enhancement and paramagnetic susceptibility effect. Growth patterns (solid : mixed : infiltrative), tumour-margin transitions in cellularity and calcification were determined histopathologically. Allelic imbalance in chromosomes 1p36 and 19q13 was determined. Thirty-three oligodendrogliomas (25 with 1p/19q loss) and 53 oligoastrocytomas (18 with 1p/19q loss) were investigated. Solid, mixed or infiltrative growth patterns were seen in grade II and grade III tumours with or without 1p/19q loss, but infiltrative growth was more common in tumours with intact 1p/19q (chi2: P = 0.029). Grade III tumours were more likely to have a solid growth pattern (chi2: P = 0.046) associated with contrast enhancement (chi2: P = 0.011). Transition in cellularity at the radiological margin did not differ according to genotype. All cases with T1 or T2 signal homogeneity had intact 1p/19q. Tumours with sharp/smooth borders were more likely to have intact 1p/19q than those with indistinct/irregular borders (chi2: P < 0.001), but this was not related to histological growth characteristics. This study identified a group of oligodendroglial tumours with intact 1p/19q displaying distinctive MR imaging features that were unrelated to the histopathology characteristics.

Differentiation between Oligodendroglioma Genotypes Using Dynamic Susceptibility Contrast Perfusion-Weighted Imaging and Proton MR Spectroscopy

“…An indistinct tumor border, heterogeneous signal intensity, and paramagnetic susceptibility are associated with oligodendrogliomas harboring 1p/19q LOH. 22,23 We observed a significantly higher susceptibility effect in oligodendrogliomas with 1p/19q deletions. Calcification and tumor-associated hemorrhage are commonly seen in oligodendrogliomas, 43 which may have contributed to the susceptibility effect in our study.…”

“…As conventional MR imaging parameters have also been used for genotyping of oligodendrogliomas, 22,23 the following imaging characteristics were also evaluated qualitatively: 1) sharp vs indistinct tumor border on T2-weighted images, 2) homogeneous vs heterogeneous tumor signal intensity on T2-weighted and T1-weighted images, 3) presence or absence of a paramagnetic susceptibility effect on T2-weighted and T2*-weighted gradient-echo EPI images, and 4) presence or absence of contrast enhancement.…”

“…33,42 We believe that increased mitotic activity of neoplastic cells in the rCBV max regions of 1p/19q LOH oligodendrogliomas may account for the increased myo-inositol and Glx levels. Some studies 22,23 have assessed the relationship between conventional MR imaging and genotypes of oligodendrogliomas. An indistinct tumor border, heterogeneous signal intensity, and paramagnetic susceptibility are associated with oligodendrogliomas harboring 1p/19q LOH.…”

Gene expression in oligodendroglial tumors

“…Two tumors were resected and H&E stained sections of frozen tissue were used to assess the pathology prior to RNA extraction. Twenty-six were sampled by frame-based, CT MRI-guided serial stereotactic biopsy performed as described previously [14], in which samples (<1 mm 3 ) are taken along a stereotactic trajectory calculated to encompass the most aggressive part of the tumor as defined by contrast enhancement or in non-enhancing cases, to maximize representation of the tumor. Further details are given in the Supplementary Information (http://www.qub.ac.uk/isco/JCO).…”

CT Imaging Correlates of Genomic Expression for Oral Cavity Squamous Cell Carcinoma

“…Correlation of imaging morphologic features to the genotype and gene expression have already been made in other tumor sites, such as the breast, liver, or brain. [7][8][9][10][11][12][13][14][15] Advantages of imaging include a larger area of coverage than pathologic specimens, which extends evaluation to tissue beyond the surgical resection margins, and less expense than combinations of multiple genomic tests, especially if obtained anyway as routine practice. If imaging findings can correlate with clinically useful molecular or genomic biomarkers, then a potential exists for improved tissue sample targeting, 8 clinical decision making, response monitoring, 16 and discovering and validating molecular targets.…”