201Thallium SPECT and 1H-MRS compared with MRI in chemotherapy monitoring of high-grade malignant astrocytomas

Brain SPECT and perfusion MRI: do they provide complementary information about the tumour lesion and its grading?

AIM

To evaluate the relative and combined utility of ^99mTc-tetrofosmin (^99mTc-TF) brain single-photon-emission computed tomography (SPECT) and dynamic susceptibility contrast (DSC) perfusion magnetic resonance imaging (MRI) in grading brain gliomas.

MATERIALS AND METHODS

Thirty-six patients with clinically suspected brain tumours were assessed by ^99mTc-TF SPECT and DSC-MRI. Brain tumour malignancy was confirmed in all patients at histopathology. On both techniques brain lesions were evaluated via visual and semi-quantitative analysis methods (deriving tetrofosmin index [T-index] and relative cerebral blood volume [rCBV] ratios, respectively).

RESULTS

^99mTc-TF SPECT showed abnormally elevated tracer uptake in 31/36 patients whereas MRI detected the brain tumour in all patients. Optimal cut-off values of each index for discriminating between low- and high-grade gliomas were obtained through receiver operating characteristic (ROC) analyses. A T-index cut-off of 6.35 ensured 82% sensitivity and 71% specificity for discriminating between high- and low-grade gliomas, whereas a relative rCBV ratio cut-off of 1.80 achieved 91% sensitivity and 100% specificity. Requiring a positive result on either technique to characterise a high-grade glioma was associated with similar specificity and slightly increased sensitivity.

CONCLUSION

Both imaging techniques, ^99mTF SPECT and DSC MRI, may provide complementary indices of tumour grade and have an independent diagnostic value for high-risk tumours.

Integration method of 3D MR spectroscopy into treatment planning system for glioblastoma IMRT dose painting with integrated simultaneous boost

Background

To integrate 3D MR spectroscopy imaging (MRSI) in the treatment planning system (TPS) for glioblastoma dose painting to guide simultaneous integrated boost (SIB) in intensity-modulated radiation therapy (IMRT).

Methods

For sixteen glioblastoma patients, we have simulated three types of dosimetry plans, one conventional plan of 60-Gy in 3D conformational radiotherapy (3D-CRT), one 60-Gy plan in IMRT and one 72-Gy plan in SIB-IMRT. All sixteen MRSI metabolic maps were integrated into TPS, using normalization with color-space conversion and threshold-based segmentation. The fusion between the metabolic maps and the planning CT scans were assessed. Dosimetry comparisons were performed between the different plans of 60-Gy 3D-CRT, 60-Gy IMRT and 72-Gy SIB-IMRT, the last plan was targeted on MRSI abnormalities and contrast enhancement (CE).

Results

Fusion assessment was performed for 160 transformations. It resulted in maximum differences <1.00 mm for translation parameters and ≤1.15° for rotation. Dosimetry plans of 72-Gy SIB-IMRT and 60-Gy IMRT showed a significantly decreased maximum dose to the brainstem (44.00 and 44.30 vs. 57.01 Gy) and decreased high dose-volumes to normal brain (19 and 20 vs. 23% and 7 and 7 vs. 12%) compared to 60-Gy 3D-CRT (p < 0.05).

Conclusions

Delivering standard doses to conventional target and higher doses to new target volumes characterized by MRSI and CE is now possible and does not increase dose to organs at risk. MRSI and CE abnormalities are now integrated for glioblastoma SIB-IMRT, concomitant with temozolomide, in an ongoing multi-institutional phase-III clinical trial. Our method of MR spectroscopy maps integration to TPS is robust and reliable; integration to neuronavigation systems with this method could also improve glioblastoma resection or guide biopsies.

Perioperative single photon emission computed tomography in predicting survival of malignant glioma patients

Single photon emission computed tomography (SPECT) is widely used in the evaluation of glioma patients and has been demonstrated to correlate with glioma malignancy and proliferation indexes. The aim of this study was to evaluate the association between perioperative technetium-99m-methoxyisobutylisonitrile ((99m)Tc-MIBI) uptake on SPECT scans and survival of malignant glioma patients. A total of 17 patients (11 males and 6 women; mean age, 62.2±8.4 years) with histologically confirmed malignant gliomas (16 glioblastoma multiforme and 1 gliosarcoma) underwent (99m)Tc-MIBI SPECT scans 2.8±1.9 days before surgery and 9.8±1.5 days after surgery. The total intensity index (TII) that corresponds to the area and intensity of tracer uptake was calculated before and after surgery. In addition, the change of TII before versus after surgery (Δ TII) was calculated. The overall survival (OS) was defined as the period between the date of surgery and the date of death. The median overall survival time was 12.4 months, ranging from 1.4 to 88 months; there were nine (45%) 12-month survivors. In univariate analyses using a log-rank test, worse OS was significantly associated with higher preoperative TII (≥12), higher postoperative TII (≥6), lower Δ TII (<50%) and higher number of neurological symptoms prior to surgery (≥4). In multivariate analyses, higher postoperative TII, a greater number of neurological symptoms and female gender were found to be factors with independent prognostic value of OS. Patients who survived more than 12 months following surgery had a significantly lower postoperative TII, higher Δ TII and greater rate of gross total resection compared to patients who survived less than 12 months following surgery. Higher peri-operative tracer uptake and lower decrease of tracer uptake following surgery (suggesting less radical resection) were associated with worse OS of malignant glioma patients. Our results suggest that SPECT may be used to predict survival of malignant glioma patients; however, further studies using larger samples are required.

Glioma residual or recurrence versus radiation necrosis: accuracy of pentavalent technetium-99m-dimercaptosuccinic acid [Tc-99m (V) DMSA] brain SPECT compared to proton magnetic resonance spectroscopy (1H-MRS): initial results

We compared pentavalent technetium-99m dimercaptosuccinic acid (Tc-99m (V) DMSA) brain single photon emission computed tomography (SPECT) and proton magnetic resonance spectroscopy ((1)H-MRS) for the detection of residual or recurrent gliomas after surgery and radiotherapy. A total of 24 glioma patients, previously operated upon and treated with radiotherapy, were studied. SPECT was acquired 2-3 h post-administration of 555-740 MBq of Tc-99m (V) DMSA. Lesion to normal (L/N) delayed uptake ratio was calculated as: mean counts of tumor ROI (L)/mean counts of normal mirror symmetric ROI (N). (1)H-MRS was performed using a 1.5-T scanner equipped with a spectroscopy package. SPECT and (1)H-MRS results were compared with pathology or follow-up neuroimaging studies. SPECT and (1)H-MRS showed concordant residue or recurrence in 9/24 (37.5%) patients. Both were true negative in 6/24 (25%) patients. SPECT and (1)H-MRS disagreed in 9 recurrences [7/9 (77.8%) and 2/9 (22.2%) were true positive by SPECT and (1)H-MRS, respectively]. Sensitivity of SPECT and (1)H-MRS in detecting recurrence was 88.8 and 61.1% with accuracies of 91.6 and 70.8%, respectively. A positive association between the delayed L/N ratio and tumor grade was found; the higher the grade, the higher is the L/N ratio (r = 0.62, P = 0.001). Tc-99m (V) DMSA brain SPECT is more accurate compared to (1)H-MRS for the detection of tumor residual tissues or recurrence in glioma patients with previous radiotherapy. It allows early and non-invasive differentiation of residual tumor or recurrence from irradiation necrosis.

Multivoxel 3D proton MR spectroscopy in the distinction of recurrent glioma from radiation injury

OBJECTIVE

To explore the usefulness of multivoxel 3D proton MR spectroscopy ((1)H-MRS) in assessing the recurrent contrast-enhancing areas at the site of the previously treated gliomas.

MATERIALS AND METHODS

In 28 patients who had new contrast-enhancing lesions in the vicinity of the previously resected and irradiated high-grade glioma, 3D (1)H-MRS examinations were performed on a 3.0T MR scanner. Spectral data for N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) were analyzed in all patients. Receiver operating characteristic analysis was performed, and the threshold value for tumor differentiation was determined. Diagnosis of these lesions was assigned by means of histopathology and follow-up.

RESULTS

Diagnostic-quality 3D (1)H-MRS with quantifiable Cho, Cr, and NAA peaks was obtained in 92.9% of the cases. The Cho/NAA and Cho/Cr ratios were significantly higher in recurrent tumor than in radiation injury (P < 0.01), whereas the NAA/Cr ratios were lower in recurrent tumor than in radiation injury (P = 0.02). The Cho/Cr and Cho/NAA ratios were significantly higher in radiation injury than in normal-appearing white matter (P < 0.01), however, the NAA/Cr ratios were lower in radiation injury than in normal-appearing white matter (P = 0.01). Using receiver operating characteristic analysis, the resulting sensitivity, specificity and diagnostic accuracy of 3D (1)H-MRS were 94.1%, 100%, and 96.2%, respectively, based on the cut-off values of 1.71 for Cho/Cr or 1.71 for Cho/NAA or both as tumor criterion.

CONCLUSION

3D (1)H-MRS could differentiate recurrent tumor from radiation injury in patients with recurrent contrast-enhancing lesions in the vicinity of the previously treated gliomas.

Distinction between recurrent glioma and radiation injury using magnetic resonance spectroscopy in combination with diffusion-weighted imaging

PURPOSE

The aim of this study was to explore the diagnostic effectiveness of magnetic resonance (MR) spectroscopy with diffusion-weighted imaging on the evaluation of the recurrent contrast-enhancing areas at the site of treated gliomas.

METHODS AND MATERIALS

In 55 patients who had new contrast-enhancing lesions in the vicinity of the previously resected and irradiated high-grade gliomas, two-dimensional MR spectroscopy and diffusion-weighted imaging were performed. Spectral data for N-acetylaspartate (NAA), choline (Cho), creatine (Cr), lipid (Lip), and lactate (Lac) were analyzed in conjunction with the apparent diffusion coefficient (ADC) in all patients. Diagnosis of these lesions was assigned by means of follow-up or histopathology.

RESULTS

The Cho/NAA and Cho/Cr ratios were significantly higher in recurrent tumor than in regions of radiation injury (p < 0.01). The ADC value and ADC ratios (ADC of contrast-enhancing lesion to matching structure in the contralateral hemisphere) were significantly higher in radiation injury regions than in recurrent tumor (p < 0.01). With MR spectroscopic data, two variables (Cho/NAA and Cho/Cr ratios) were shown to differentiate recurrent glioma from radiation injury, and 85.5% of total subjects were correctly classified into groups. However, with discriminant analysis of MR spectroscopy imaging plus diffusion-weighted imaging, three variables (Cho/NAA, Cho/Cr, and ADC ratio) were identified and 96.4% of total subjects were correctly classified. There was a significant difference between the diagnostic accuracy of the two discriminant analyses (Chi-square = 3.96, p = 0.046).

CONCLUSION

Using discriminant analysis, this study found that MR spectroscopy in combination with ADC ratio, rather than ADC value, can improve the ability to differentiate recurrent glioma and radiation injury.

Phase II study of high-dose chemotherapy before radiation in children with newly diagnosed high-grade astrocytoma: final analysis of Children's Cancer Group Study 9933

BACKGROUND

High-grade astrocytomas (HGA) carry a dismal prognosis and compose nearly 20% of all childhood brain tumors. The role of high-dose chemotherapy (HDCT) in the treatment of HGA remains unclear.

METHODS

In a nationwide study, The Children's Cancer Group (CCG) prospectively evaluated 102 children with HGA and postoperative residual disease for efficacy and toxicity of four courses of HDCT before radiotherapy (RT). Patients were randomly assigned to one of three couplets of drugs: carboplatin/etoposide (Regimen A), ifosfamide/etoposide (Regimen B), or cyclophosphamide/etoposide (Regimen C). After HDCT, all patients were to receive local RT followed by lomustine and vincristine. Twenty-six patients were excluded after central neuroradiographic review (n = 8) or pathology review (n = 18).

RESULTS

Of 76 evaluable patients (median age, 11.95 yrs; range, 3-20 yrs), 30 patients relapsed during HDCT, and 11 others did not complete HDCT because of toxicity. Nonhematologic serious toxicities were common (29%), and 21% of patients did not receive RT. Objective response rates were not associated with amount of residual disease and did not statistically differ between regimens: 27% (Regimen A), 8% (Regimen B), and 29% (Regimen C). Overall survival (OS) was 24% +/- 5% at 5 years and did not differ between groups. Median time to an event was longest for Regimen A (283 days compared with 83 and 91 days for Regimens B and C, respectively). The five-year, event-free survival (EFS) rate for all patients was 8% +/- 3% and 14% +/- 7% for Regimen A (P = 0.07).

CONCLUSIONS

OS and EFS were not affected by histologic grade. Patients who responded to HDCT had a nominally higher survival rate (P = 0.03 for trend). The authors conclude that these commonly used HDCT regimens provide no additional clinical benefit to conventional treatment in HGA, regardless of the amount of measurable residual tumor.

Thallium-201 SPECT: the optimal prediction of response in glioma therapy

PURPOSE

The aim of this study was to estimate 201Tl SPECT and CT-MRI cut-off values that lead to a validated prognostic classification for the end-point overall survival, in order to discriminate glioma patients with good and poor prognosis at an early stage during chemotherapeutic treatment.

METHODS

We studied patients who underwent 201Tl SPECT and CT-MRI before and after two courses of chemotherapy. Cut-off values were retrieved from the Cox model. Patients were classified according to the computed cut-off values, creating subgroups of patients with different prognosis in terms of survival [tumour regression (TR); stable disease (SD); tumour progression (TP)]. The differences between the subgroups were assessed by Kaplan-Meier analyses. The predictive performance of the classification procedure was evaluated by a leave-one-out cross-validation method.

RESULTS

201Tl SPECT classified 41% of the patients as SD, 25% as TR and 34% as TP. CT-MRI classified 82% of the patients as SD, and only 4% and 14% as TR and TP, respectively. Of those patients with a relatively long overall survival (i.e. > or =16 months), cross-validation estimates of 201Tl SPECT classification rates were 50% TR and 50% SD, and cross-validation estimates of CT-MRI classification rates were 7% TR, 72% SD, and 21% TP.

CONCLUSION

We constructed a 201Tl SPECT model that makes it possible to identify glioma patients with a good or a poor prognosis at an early stage during chemotherapeutic treatment. With this model, accurate predictions can be made with regard to the expected duration of survival.

123I-IMT SPECT and 1H MR-spectroscopy at 3.0 T in the differential diagnosis of recurrent or residual gliomas: a comparative study

The aim of this investigation was to compare two current non-invasive modalities, single photon emission tomography (SPECT) using 123-iodine-alpha-methyl tyrosine (123I-IMT) and single-voxel proton magnetic resonance spectroscopy (1H-MRS) at 3.0 T, with regard to their ability to differentiate between residual/ recurrent tumors and treatment-related changes in patients pretreated for glioma. The patient population comprised 25 patients in whom recurrent glioma was suspected based on MR imaging. SPECT imaging started 10 min after iv. injection of 300-370 MBq 123I-IMT and was performed using a triple-head system. The IMT uptake was calculated semiquantitatively using regions-of-interest. 1H-MRS was performed at 3.0 T using the single-volume point-resolved spectroscopy (PRESS) technique. Guided by MR imaging volumes-of-interest for spectroscopy were placed into the suspected lesions. Signal intensities of choline-containing compounds (Cho), creatine and phosphocreatine (Cr), and N-acetylaspartate (NAA) were obtained. When using the cut-off of 1.62 for 123I-IMT uptake, the sensitivity, specificity, and accuracy of the 123I-IMT SPECT were 95, 100 and 96%, respectively. For 1H-MRS, the sensitivity, specificity and accuracy were 89, 83 and 88%, respectively, based both on the metabolic ratios of Cho/Cr and Cho/NAA as tumor criterion with cut-off values of 1.11 and 1.17, respectively. In conclusion, 123I-IMT SPECT yielded more favorable results compared to 1H-MRS at distinguishing recurrent and/or residual glioma from post-therapeutic changes and may be particularly valuable when the evaluation of tumor extent is necessary.

Thallium-201 single-photon emission computed tomography as an early predictor of outcome in recurrent glioma

PURPOSE

With limited response rates and potential toxicity of chemotherapeutic treatment in patients with recurrent glioma, reliable response assessment is essential. Currently, the assessment of treatment response in glioma patients is based on the combination of radiologic and clinical findings. However, response monitoring with computed tomography (CT) or magnetic resonance imaging (MRI) is hampered by several pitfalls and is prone to interobserver variability. The aim of this study was to establish the value of thallium-201 single-photon emission computed tomography (201Tl-SPECT) as a predictor of overall survival and response to chemotherapy in recurrent glioma, and to compare the value of 201Tl-SPECT with that of CT and MRI.

PATIENTS AND METHODS

We studied patients who underwent CT or MRI and 201Tl-SPECT before chemotherapy (n = 57), and patients who also had undergone CT or MRI and 201Tl-SPECT after two courses of chemotherapy (n = 44). The value of the radiologic variables (CT-MRI tumor size, 201Tl-SPECT tumor size, and maximal tumor intensity) at baseline and at follow-up in predicting overall survival, and the percentage of patients alive and progression-free at 6 months (APF6) were examined using Cox regression and logistic regression analysis.

RESULTS

Both at baseline and at follow-up, 201Tl-SPECT maximal tumor intensity was the strongest predictive variable and was inversely related to overall survival and APF6. In particular, progression of maximal tumor intensity after two courses of chemotherapy was a powerful predictor of poor outcome.

CONCLUSION

201Tl-SPECT is superior to conventional CT-MRI in the early prediction of overall survival and response to chemotherapy in patients with recurrent glioma.

Use of 201Tl SPECT imaging to assess the response to therapy in patients with high grade gliomas

PURPOSE

To assess the potential role of 201Tl single photon emission tomography (201-Thallium SPECT) when compared to other imaging modalities in the evaluation of the response to therapy in high grade gliomas.

MATERIALS AND METHODS

Twenty patients with histologically proved high grade glioma have been included: 15 with glioblastoma (GBM), 3 with anaplastic astrocytoma (AA) and 2 with anaplastic oligoastrocytoma (AOA). Patients were assessed by 201Tl SPECT, computed tomography (CT) and magnetic resonance imaging (MRI) at (a) either at the moment of maximum response to first line chemotherapy, or after the completion of radiotherapy and chemotherapy if post-surgical residual disease was present, and (b) after the completion of second line chemotherapy if disease persisted, or either a relapse or disease progression was confirmed. Final response was evaluated according to the McDonald criteria, and by comparing SPECT, CT and MRI results.

RESULTS

According to the McDonald criteria, clinical response after first line chemotherapy was 5 partial response, 7 stable disease and 8 progressive disease. Evaluation by 201Tl SPECT was in agreement with such criteria in nearly all patients (90%). MRI findings closely agreed with the clinical follow-up. CT findings clearly differed from those observed by SPECT and MRI. After second line therapy, 10 patients progressed, 3 had stable disease and 7 had partial response. 201Tl SPECT agreed with the clinical status in 89% cases, whereas MRI and, specially CT, fared significantly lower.

CONCLUSION

Compared to conventional neuroimaging, 201Tl SPECT added valuable information in the assessment of the response to therapy in our patient population; whenever findings were not conclusive and in the case of disagreement between CT and MRI findings.