Histological heterogeneity of neuroradiologically suspected adult low grade gliomas detected by Xenon enhanced computerized tomography (CT)

Summary

Xenon-enhanced computerized tomography (XeCT) was performed on 14 consecutive adult patients presenting with seizures showing supratentorial non-enhancing radiologically uniform appearing low grade gliomas on CT/MR images. Pre-operative XeCT patterns were compared with postoperative histological diagnosis, grading and Ki67 proliferation indices (PI).

After gross-total, subtotal resection or biopsy, 11 astrocytomas, 2 oligodendrogliomas and 1 oligo-astrocytoma were diagnosed and graded: Grade I: 2 patients (Ki67-PI=0.5–0.8), Grade I–II: 4 patients (Ki67-PI=0.3–1.5), Grade II: 3 patients (Ki67-PI=0.5–3.5), Grade II–III: 4 patients (Ki67-PI=3.8–6.8) and Grade III: 1 patient (Ki67-PI=5.2), (Kernohan Classification). Xenon CT studies revealed different flow patterns, correlating with the postoperative histological diagnosis, grading and proliferation indices: A tumour group with well defined, delayed, only minimally enhancing tumour area (5 patients, Grade I, I–II or II), a second group with less well defined low-flow-area borders and inhomogenous, strong enhancement within the tumour (4 patients, Grade II–III, III) and a third group with fast enhancing tumours was identified. The third pattern was exclusively shown in the 2 oligodendrogliomas (Grade I and II–III) and 1 oligo-astrocytoma (Grade II).

The preliminary report identifies the Xenon enhanced CT as a beneficial pre-operative investigation for patients with radiologically uniform appearing suspected adult supratentorial low-grade gliomas, which may give information about the presence of anaplastic foci or oligodendroglial components.