Detection of recurrent gliomas with quantitative thallium-201/technetium-99m HMPAO single-photon emission computerized tomography

Abstract

Deteriorating clinical status after high-dose radiation therapy for high-grade gliomas may be due to radiation changes or may signal recurrent or residual tumor mass. The two conditions cannot be distinguished reliably by computerized tomography (CT) or magnetic resonance (MR) imaging. The authors assessed the ability of sequential thallium-201 chloride (201Tl) and technetium-99m hexamethylpropylene amine oxime (99mTc HMPAO) single-photon emission CT (SPECT) to distinguish tumor recurrence from radiation changes after high-dose (greater than or equal to 600 cGy) radiation therapy for malignant gliomas. Preoperative tumor/nontumor uptake ratios were analyzed in 32 patients and correlated with the presence of gross tumor at the time of reoperation. In 12 of 13 patients with 201Tl tumor/scalp ratios of 3.5 or greater, recurrent tumor was present. The authors found 99mTc HMPAO SPECT to be useful for identifying the absence of solid tumor recurrence in patients with low to moderate 201Tl uptake (ratio 1.1 to 3.4) and low perfusion to that site. In 11 of 12 patients with 99mTc HMPAO tumor/cerebellum ratios of 0.50 or less, no recurrent tumor mass was present. Three of seven patients with 201Tl ratios of 3.4 or less and 99mTc HMPAO ratios of 0.51 or more had recurrent tumor found at surgery; thus the test was not predictive in this group. It is concluded that the use of sequential 201Tl and 99mTc HMPAO SPECT accurately identifies the presence of tumor recurrence versus radiation changes in most patients with high-grade astrocytomas who have undergone tumor resection and high-dose radiation therapy.

Dual isotope single-photon emission computerized tomography used for prediction of histology and survival in patients after high-dose radiotherapy for malignant astrocytoma

“…The present investigation expands these earlier analyses by establishing more detailed correlations of SPECT data with histopathological findings and patient survival time in a large homogeneous population of patients with high-grade astrocytomas. In agreement with preliminary results in previous studies, [5,27] we found that all patients with Tl-201 lesion/scalp ratios greater than 3.5 had high Tc-99m HMPAO uptake (greater than 0.5 that of the cerebellum) as well; these patients (Group III) tended to have highly cellular tumor recurrences on biopsy and had worse survival times at 1 year than all other patients. We further defined a subgroup of patients with Tl-201 uptake ratios between 2 and 3.5 (Group II), which was composed predominantly of patients with less cellular tumor recurrences and with better 1-year survival times (42%) than the patients in Group III (7% 1-year survival); in Groups II and III, Tc-99m HMPAO uptake did not contribute significantly to the results of the analysis.…”

“…It has been shown that dual-isotope SPECT using Tc-99m HMPAO, a brain perfusion agent that crosses the intact BBB, is more accurate than Tl-201 alone in discriminating radiation changes from recurrence. [5,27,36] The present report correlates the results of dual-isotope SPECT scanning with survival times and histopathological findings in a large population of patients treated with radiotherapy for either an AA or a GBM.…”

“…Some of these patients were included in a preliminary report from this institution. [5] All patients were treated initially by bulk tumor resection, conventional radiotherapy (1.8 Gy daily, 5 days/week, for a total dose of 59.4 Gy), and high-dose local radiotherapy, consisting of either iodine-125 radiation implants (12 patients) or stereotactic radiosurgery using a 6-MV linear accelerator (38 patients). Implants (brachytherapy) produced an approximately 50 Gy minimum dose over a 5-day period, and radiosurgery produced a 10 to 20 Gy dose in a single fraction.…”

“…Projections were processed and reconstructed using techniques detailed previously. [5,27] The axial tomograms were displayed on a 128 X 128 matrix (1.67-sq mm pixel size) as a set of 64 slices (1.76-mm slice thickness). These slices were summed to give a final display of 21 slices, with a slice thickness of 5 mm.…”

MR Spectroscopy in Radiation Injury

“…That study also showed that the ADC ratios in the white matter tracts in the perilesional edema were significantly higher in patients with radiation injury compared with those with recurrent tumor and that the fractional anisotropy (FA) ratios were significantly higher in normal-appearing white matter tracts adjacent to the edema in patients diagnosed with radiation injury compared with those with recurrent tumors. 7 Thallium 201 ( 201 Tl) or 99mTc hexamethylpropyleneamine oxime single-photon emission tomography (HMPAO SPECT) or both [12][13][14] have been reported as useful techniques to discriminate tumor progression and radiation injury. It has been suggested that the combination of lowthallium and low-HMPAO uptake was associated with benign radiation change; whereas increased uptake of either agent or both was associated with recurrent/persistent tumor at biopsy and a poor prognosis.…”