A comparative study of thallium-201 SPET, carbon-11 methionine PET and fluorine-18 fluorodeoxyglucose PET for the differentiation of astrocytic tumours

Prediction of nuclide accumulation spread based on the volume of enhancing magnetic resonance imaging lesion in glioblastoma patients

BACKGROUND

11C-methionine-PET (MET) and Thallium-201 chloride-SPECT (TL) are useful for predictive proliferation ability and tumor invasion range identification in glioma patients, however they are not always possible in any hospital or country. Our study aimed to assess whether the range of MET and Tl accumulation could be predicted from the contrast-enhanced lesions in Gadolinium (Gd)-T1 weighted magnetic resonance image in glioblastoma multiforme (GBM) patients.

METHODS

In 25 cases, the MET-area, TL-area, O-area where MET and TL overlap, and all accumulation area (AA-area) were measured in the same axial cross section as the Gd enhanced maximum area (Gd-area). This tracing operation was repeated with all axial fusion slices, and each volume was also measured (Gd-V, MET-V, TL-V, O-V, AA-V).

RESULTS

The maximum accumulation distance of MET and TL beyond the Gd-area was limited to within 30 mm, 35 mm, respectively. Significant positive correlations were showed in all combinations with Gd-area: MET-area (r=0.851, P<0.0001), TL-area (r=0.955, P<0.0001), O-area (r=0.935, P<0.0001) and AA-area (r=0.893, P<0.0001), respectively. All combinations with Gd-V showed significant positive correlation: MET-V (r=0.867, P<0.0001), TL-V (r=0.952, P<0.0001), O-V (r=0.935, P<0.0001) and AA-V (r=0.897, P<0.0001), respectively.

CONCLUSIONS

Approximate tumor volume Gd-V can be calculated using the formula A * B * C / 2, where A, B, and C represent the dimensions of Gd-enhanced lesion in 3 axes perpendicular to each other. The nuclide accumulation predictive table created using the obtained linear approximation functions can be used to predict the average tumor invasion range from the Gd-V without preoperative nuclear examinations.

Non-FDG PET/CT

The major applications for molecular imaging with PET in clinical practice concern cancer imaging. Undoubtedly, 18F-FDG represents the backbone of nuclear oncology as it remains so far the most widely employed positron emitter compound. The acquired knowledge on cancer features, however, allowed the recognition in the last decades of multiple metabolic or pathogenic pathways within the cancer cells, which stimulated the development of novel radiopharmaceuticals. An endless list of PET tracers, substantially covering all hallmarks of cancer, has entered clinical routine or is being investigated in diagnostic trials. Some of them guard significant clinical applications, whereas others mostly bear a huge potential. This chapter summarizes a selected list of non-FDG PET tracers, described based on their introduction into and impact on clinical practice.

The Relationship Between IDH1 Mutation Status and Metabolic Imaging in Nonenhancing Supratentorial Diffuse Gliomas: A 11C-MET PET Study

Purpose:

We evaluated the relationship between isocitrate dehydrogenase 1 (IDH1) mutation status and metabolic imaging in patients with nonenhancing supratentorial diffuse gliomas using ¹¹C-methionine positron emission tomography (¹¹C-MET PET).

Materials and Methods:

Between June 2012 and November 2017, we enrolled 86 (38 women and 48 men; mean age, 41.9 ± 13.1 years [range, 8-67 years]) patients with newly diagnosed supratentorial diffuse gliomas. All patients underwent preoperative ¹¹C-MET PET. Tumor samples were obtained and immunohistochemically analyzed for IDH1 mutation status.

Results:

The mutant and wild-type IDH1 diffuse gliomas had significantly different mean maximum standardized uptake value values (2.73 [95% confidence interval, CI: 2.32-3.16] vs 3.85 [95% CI: 3.22-4.51], respectively; P = .004) and mean tumor-to-background ratio (1.90 [95% CI: 1.65-2.16] vs 2.59 [95% CI: 2.17-3.04], respectively; P = .007).

Conclusions:

¹¹C-methionine PET can noninvasively evaluate the IDH1 mutation status of patients with nonenhancing supratentorial diffuse gliomas.

Diagnostic accuracy of 13N-ammonia PET, 11C-methionine PET and 18F-fluorodeoxyglucose PET: a comparative study in patients with suspected cerebral glioma

Background

The treatment of patients with glioma depended on the nature of the lesion and on histological grade of the tumor. Positron emission tomography (PET) using ¹³N-ammonia (NH₃), ¹¹C-methionine (MET) and ¹⁸F-fluorodeoxyglucose (FDG) have been used to assess brain tumors. Our aim was to compare their diagnostic accuracies in patients with suspected cerebral glioma.

Methods

Ninety patients with suspicion of glioma based on previous CT/MRI, who underwent NH₃ PET, MET PET and FDG PET, were prospectively enrolled in the study. The reference standard was established by histology or clinical and radiological follow-up. Images were interpreted by visual evaluation and semi-quantitative analysis using the lesion-to-normal white matter uptake ratio (L/WM ratio).

Results

Finally, 30 high-grade gliomas (HGG), 27 low-grade gliomas (LGG), 10 non-glioma tumors and 23 non-neoplastic lesions (NNL) were diagnosed. On visual evaluation, sensitivity and specificity for differentiating tumors from NNL were 62.7% (42/67) and 95.7% (22/23) for NH₃ PET, 94.0% (63/67) and 56.5% (13/23) for MET PET, and 35.8% (24/67) and 65.2% (15/23) for FDG PET. On semi-quantitative analysis, brain tumors showed significantly higher L/WM ratios than NNL both in NH₃ and MET PET (both P < 0.001). The sensitivity, specificity and the area under the curve (AUC) by receiver operating characteristic (ROC) analysis, respectively, were 64.2, 100% and 0.819 for NH₃; and 89.6, 69.6% and 0.840 for MET. Besides, the L/WM ratios of NH₃, MET and FDG PET in HGG all significantly higher than that in LGG (all P < 0.001). The predicted (by ROC) accuracy of the tracers (AUC shown in parentheses) were 86.0% (0.896) for NH₃, 87.7% (0.928) for MET and 93.0% (0.964) for FDG. While no significant differences in the AUC were seen between them.

Conclusion

NH₃ PET has remarkably high specificity for the differentiation of brain tumors from NNL, but low sensitivity for the detection of LGG. MET PET was found to be highly useful for detection of brain tumors. However, like FDG, high MET uptake is frequently observed in some NNL. NH₃, MET and FDG PET all appears to be valuable for evaluating the histological grade of gliomas.

Differential Diagnosis between Low-Grade and High-Grade Astrocytoma Using System A Amino Acid Transport PET Imaging with C-11-MeAIB: A Comparison Study with C-11-Methionine PET Imaging

Introductions

[N-methyl-C-11]α-Methylaminoisobutyric acid (MeAIB) is an artificial amino acid radiotracer used for PET study, which is metabolically stable in vivo. In addition, MeAIB is transported by system A neutral amino acid transport, which is observed ubiquitously in all types of mammalian cells. It has already been shown that MeAIB-PET is useful for malignant lymphoma, head and neck cancers, and lung tumors. However, there have been no reports evaluating the usefulness of MeAIB-PET in the diagnosis of brain tumors. The purpose of this study is to investigate the efficacy of system A amino acid transport PET imaging, MeAIB-PET, in clinical brain tumor diagnosis compared to [S-methyl-C-11]-L-methionine (MET)-PET.

Methods

Thirty-one consecutive patients (male: 16, female: 15), who were suspected of having brain tumors, received both MeAIB-PET and MET-PET within a 2-week interval. All patients were classified into two groups: Group A as a benign group, which included patients who were diagnosed as low-grade astrocytoma, grade II or less, or other low-grade astrocytoma (n=12) and Group B as a malignant group, which included patients who were diagnosed as anaplastic astrocytoma, glioblastoma multiforme (GBM), or recurrent GBM despite prior surgery or chemoradiotherapy (n=19). PET imaging was performed 20 min after the IV injection of MeAIB and MET, respectively. Semiquantitative analyses of MeAIB and MET uptake using SUVmax and tumor-to-contralateral normal brain tissue (T/N) ratio were evaluated to compare these PET images. ROC analyses for the diagnostic accuracy of MeAIB-PET and MET-PET were also calculated.

Results

In MeAIB-PET imaging, the SUVmax was 1.20 ± 1.29 for the benign group and 2.94 ± 1.22 for the malignant group (p < 0.005), and the T/N ratio was 3.77 ± 2.39 for the benign group and 16.83 ± 2.39 for the malignant group (p < 0.001). In MET-PET, the SUVmax was 3.01 ± 0.94 for the benign group and 4.72 ± 1.61 for the malignant group (p < 0.005), and the T/N ratio was 2.64 ± 1.40 for the benign group and 3.21 ± 1.14 for the malignant group (n.s.). For the analysis using the T/N ratio, there was a significant difference between the benign and malignant groups with MeAIB-PET with p < 0.001. The result of ROC analysis using the T/N ratio indicated a better diagnosis accuracy for MeAIB-PET for brain tumors than MET-PET (p < 0.01).

Conclusions

MeAIB, a system A amino acid transport-specific radiolabeled agents, could provide better assessments for detecting malignant type brain tumors. In a differential diagnosis between low-grade and high-grade astrocytoma, MeAIB-PET is a useful diagnostic imaging tool, especially in evaluations using the T/N ratio.

Clinical trial registration

This trial was registered with UMIN000032498.

Prognostic Significance of Interim 11C-Methionine PET/CT in Primary Central Nervous System Lymphoma

PURPOSE

Primary central nervous system lymphoma (PCNSL) has a poor prognosis. There has been limited study evaluating the role of interim PET/CT in PCNSL. This prospective study investigated the interim response using sequential brain PET/CT with C-methionine (C-MET) to provide prognostic information during the treatment of PCNSL.

MATERIALS AND METHODS

A total of 26 immunocompetent patients recently diagnosed with PCNSL were evaluated. Brain MRI and C-MET PET/CT were performed at the time of diagnosis and after 4 cycles of high-dose methotrexate-based induction chemotherapy. Tumor-to-normal tissue (T/N) ratio and MTV were used to assess the interim response.

RESULTS

All patients had diffuse large B-cell lymphoma. No differences were observed in initial tumor volume or quantitative uptake among the International Extranodal Lymphoma Study Group groups. Higher International Extranodal Lymphoma Study Group risk scores were associated with higher median values for interim MTV and T/N ratios, as well as poor outcomes. After a median follow-up of 21 months, interim C-MET PET/CT assessments based on the quantitative T/N ratio and MTV predicted progression-free survival and overall survival, respectively. A high interim T/N ratio was significantly associated with decreased progression-free survival (hazards ratio, 3.68; P = 0.044).

CONCLUSIONS

Response assessments based on interim C-MET PET/CT could predict the therapeutic outcome of PCNSL.

Differential diagnosis of posterior fossa brain tumors: Multiple discriminant analysis of Tl-SPECT and FDG-PET

This study investigated the combined capability of thallium-201 (Tl)-SPECT and fluorine-18-fluoro-deoxy-glucose (FDG)-PET for differential diagnosis of posterior fossa brain tumors using multiple discriminant analysis.This retrospective study was conducted under approval of the institutional review board. In the hospital information system, 27 patients with posterior fossa intra-axial tumor between January 2009 and June 2015 were enrolled and grouped as the following 7 entities: low grade glioma (LGG) 6, anaplastic astrocytoma (AA) 2, glioblastoma (GBM) 3, medulloblastoma (MB) 3, hemangioblastoma (HB) 6, metastatic tumor (Mets) 3, and malignant lymphoma (ML) 4. Tl and FDG uptakes were measured at the tumors and control areas, and several indexes were derived. Using indexes selected by the stepwise method, discriminant analysis was conducted with leave-one-out cross-validation.The predicted accuracy for tumor classification was 70.4% at initial analysis and 55.6% at cross-validation to differentiate 7 tumor entities. HB, LGG, and ML were well-discriminated, but AA was located next to LGG. GBM, MB, and Mets largely overlapped and could not be well distinguished even applying multiple discriminant analysis. Correct classification in the original and cross-validation analyses was 44.4% and 33.3% for Tl-SPECT and 55.6% and 48.1% for FDG-PET.

Cyclooxygenase-2 Induction by Amino Acid Deprivation Requires p38 Mitogen-Activated Protein Kinase in Human Glioma Cells

Glioblastomas (GBMs) are malignant brain tumors that can outstrip nutrient supplies due to rapid growth. Cyclooxygenase-2 (COX-2) has been linked to GBMs and may contribute to their aggressive phenotypes. Amino acid starvation results in COX-2 mRNA and protein induction in multiple human glioma cell lines in a process requiring p38 mitogen-activated protein kinase (p38-MAPK) and the Sp1 transcription factor. Increased vascular endothelial growth factor expression results from starvation-dependent COX-2 induction. These data suggest that COX-2 induction with amino acid deprivation may be a part of the adaptation of glioma cells to these conditions, and potentially alter cellular response to anti-neoplastic therapy.

Simultaneous 11C-Methionine Positron Emission Tomography/Magnetic Resonance Imaging of Suspected Primary Brain Tumors

Introduction

The objective of this study was to assess the diagnostic value of integrated 11C- methionine PET/MRI for suspected primary brain tumors, in comparison to MRI alone.

Material and Methods

Forty-eight consecutive patients with suspected primary brain tumor were prospectively enrolled for an integrated 11C-methionine PET/MRI. Two neuro-radiologists separately evaluated the MRI alone and the integrated PET/MRI data sets regarding most likely diagnosis and diagnostic confidence on a 5-point scale. Reference standard was histopathology or follow-up imaging.

Results

Fifty-one suspicious lesions were detected: 16 high-grade glioma and 25 low-grade glioma. Ten non-malignant cerebral lesions were described by the reference standard. MRI alone and integrated PET/MRI each correctly classified 42 of the 51 lesions (82.4%) as neoplastic lesions (WHO grade II, III and IV) or non-malignant lesions (infectious and neoplastic lesions). Diagnostic confidence for all lesions, low-grade astrocytoma and high-grade astrocytoma (3.7 vs. 4.2, 3,1 vs. 3.8, 4.0 vs. 4,7) were significantly (p < 0.05) better with integrated PET/MRI than in MRI alone.

Conclusions

The present study demonstrates the high potential of integrated 11C-methionine-PET/MRI for the assessment of suspected primary brain tumors. Although integrated methionine PET/MRI does not lead to an improvement of correct diagnoses, diagnostic confidence is significantly improved.

Optimization of scan initiation timing after 11C-methionine administration for the diagnosis of suspected recurrent brain tumors

OBJECTIVE

¹¹C-Methionine (MET) positron emission tomography (PET) imaging is a valuable technique for the evaluation of primary and recurrent brain tumors. Many studies have used MET-PET for data acquisition starting at 20 min after the tracer injection, while others have used scan initiation times at 5-15 min postinjection. No previous studies have identified the best acquisition timing during MET-PET imaging for suspected recurrent brain tumors. Here we sought to determine the optimal scan initiating timing after MET administration for the detection of recurrent brain tumors.

MATERIALS AND METHODS

Twenty-three consecutive patients with suspected recurrent brain tumors underwent MET-PET examinations. Brain PET images were reconstructed from the four serial data sets (10-15, 15-20, 20-25, and 25-30 min postinjection) that were obtained using the list-mode acquisition technique. We determined the maximal standardized uptake values (SUVmax) of the target lesions and the target-to-normal-tissue ratios (TNRs), calculated as the SUVmax to the SUVmean of a region of interest placed on the normal contralateral frontal cortex. Target lesions without significant MET uptake were excluded.

RESULTS

Thirty-one lesions from 23 patients were enrolled. There were no significant differences in MET SUVmax or TNR values among the PET images that were reconstructed with the data extracted from the four phases postinjection.

CONCLUSION

The MET uptake in the suspected recurrent brain tumors was comparable among all data extraction time phases from 10 to 30 min postinjection. The scan initiation time of MET-PET at 10 min after the injection is allowable for the detection of recurrent brain tumors. The registration identification number of the original study is 1002.

A comparison study of (11)C-methionine and (18)F-fluorodeoxyglucose positron emission tomography-computed tomography scans in evaluation of patients with recurrent brain tumors

Introduction:

¹¹C-methonine ([¹¹C]-MET) positron emission tomography-computed tomography (PET-CT) is a well-established technique for evaluation of tumor for diagnosis and treatment planning in neurooncology. [¹¹C]-MET reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging (MRI) in stereotactic biopsy planning. This study compared fluorodeoxyglucose (FDG) PET-CT and MET PET-CT in the detection of various brain tumors.

Materials and Methods:

Sixty-four subjects of brain tumor treated by surgery, chemotherapy, and/or radiotherapy were subjected to [¹⁸F]-FDG, [¹¹C]-MET, and MRI scan. The lesion was analyzed semiquantitatively using tumor to normal contralateral ratio. The diagnosis was confirmed by surgery, stereotactic biopsy, clinical follow-up, MRI, or CT scans.

Results:

Tumor recurrence was found in 5 out of 22 patients on [F-18] FDG scan while [¹¹C]-MET was able to detect recurrence in 18 out of 22 patients in low-grade gliomas. Two of these patients were false positive for the presence of recurrence of tumor and later found to be harboring necrosis. Among oligodendroglioma, medulloblastoma and high-grade glioma out of 42 patients 39 were found to be concordant MET and FDG scans. On semiquantitative analysis, mean T/NT ratio was found to be 2.96 ± 0.94 for lesions positive for recurrence of tumors and 1.18 ± 0.74 for lesions negative for recurrence of tumor on [¹¹C]-MET scan. While the ratio for FDG scan on semiquantitative analysis was found to be 2.05 ± 1.04 for lesions positive for recurrence of tumors and 0.52 ± 0.15 for lesions negative for recurrence of tumors.

Conclusion:

The study highlight that [¹¹C]-MET is superior to [¹⁸F]-FDG PET scans to detect recurrence in low-grade glioma. A cut-off value of target to nontarget value of 1.47 is a useful parameter to distinguish benign from malignant lesion on an [¹¹C]-MET Scan. Both [¹⁸F]-FDG and [¹¹C]-MET scans were found to be useful in high-grade astrocytoma, oligodendroglioma, and medulloblastoma.

Radiological features of cerebellar glioblastoma

BACKGROUND AND PROPOSE

Glioblastoma (GBM) is the most common type of malignant primary central nervous system tumor in adults; however, the prevalence of GBM arising in the cerebellum is extremely low. This study aimed to demonstrate the radiological features of cerebellar GBMs, including computed tomography (CT), magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and (18)F-fluorodeoxyglucose (FDG)- and (11)C methionine (MET)-positron emission tomography (PET) findings.

MATERIALS AND METHODS

We retrospectively reviewed seven patients with cerebellar GBM (six men and one woman: mean age: 56 years, range: 18-73 years). We reviewed medical records and radiological data, including preoperative CT, MRI and PET. All patients underwent CT and MRI. DWI data were acquired in four patients. Three patients underwent FDG- and MET-PET examinations. All patients underwent total or subtotal tumor resection and received pathological diagnoses.

RESULTS

Four patients had imaging findings consistent with GBM and received preoperative cerebellar GBM diagnoses. Two patients exhibited homogeneous patchy and nodular enhancement without necrosis on MRI, which resembled malignant lymphoma and metastasis. One case exhibited Lhermitte-Duclos disease-like parallel linear striations (i.e.,"tiger-striped" appearance). Although the imaging findings of these three patients were inconsistent with GBM, pathological diagnosis confirmed cerebellar GMB.

CONCLUSIONS

Some evaluated cases of cerebellar GBM did not exhibit the common CT, MRI, and PET findings of supratentrial GBM, leading to considerable difficulty with preoperative differential diagnosis.

Correlation of 4'-[methyl-(11)C]-thiothymidine uptake with Ki-67 immunohistochemistry and tumor grade in patients with newly diagnosed gliomas in comparison with (11)C-methionine uptake

OBJECTIVE

A novel radiopharmaceutical, 4'-[methyl-(11)C]thiothymidine ((11)C-4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. The purpose of this study was to evaluate (11)C-4DST uptake in patients with newly diagnosed glioma and to correlate the results with proliferative activity and tumor grade, in comparison with L-[methyl-(11)C]-methionine ((11)C-MET).

METHODS

Investigations of (11)C-4DST and (11)C-MET PET/CT were performed retrospectively in 23 patients with newly diagnosed glioma. The maximum standardized uptake value (SUVmax) for tumor (T) and the mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Metabolic tumor volume (MTV) was defined as the volume with a threshold of 40% of the SUVmax. Proliferative activity as indicated by the Ki-67 index was estimated in tissue specimens.

RESULTS

Of 23 gliomas examined, (11)C-4DST PET/CT and (11)C-MET PET/CT detected 20 and 22, respectively. Linear regression analysis between (11)C-4DST and (11)C-MET indicated a weak correlation for SUVmax (r = 0.54, P < 0.008), for T/N ratio (r = 0.56, P < 0.006), and for MTV (r = 0.60, P < 0.003). Linear regression analysis indicated a weak correlation between (11)C-4DST and Ki-67 index for SUVmax (r = 0.46, P < 0.03), for T/N ratio (r = 0.43, P < 0.05), and for MTV (r = 0.68, P < 0.001) and between (11)C-MET MTV and Ki-67 index (r = 0.43, P < 0.04). Using (11)C-4DST, there was a significant difference in SUVmax between grades II and IV (P < 0.03) and in MTV between grades II and IV (P < 0.009) and grades III and IV (P < 0.02). Using (11)C-MET, there was a significant difference in SUVmax (P < 0.009) and T/N ratio (P < 0.02) between grades II and IV and in MTV between grades II and IV (P < 0.03) and grades III and IV (P < 0.02).

CONCLUSION

(11)C-4DST PET/CT is feasible for imaging of brain gliomas, as well as (11)C-MET PET/CT. Especially, it showed the highest correlation coefficient between (11)C-4DST MTV and Ki-67 index in newly diagnosed gliomas.

PET probes beyond (18)F-FDG

During the past several decades, positron emission tomography (PET) has been one of the rapidly growing areas of medical imaging; particularly, its applications in routine oncological practice have been widely recognized. At present, (18)F-fluorodeoxyglucose ((18)F-FDG) is the most broadly used PET probe. However, (18)F-FDG also suffers many limitations. Thus, scientists and clinicians are greatly interested in exploring and developing new PET imaging probes with high affinity and specificity. In this review, we briefly summarize the representative PET probes beyond (18)F-FDG that are available for patients imaging in three major clinical areas (oncology, neurology and cardiology), and we also discuss the feasibility and trends in developing new PET probes for personalized medicine.

Applications of positron emission tomography in neuro-oncology: a clinical approach

The field of neuro-oncology is concerned with some of the most challenging and difficult to treat conditions in medicine. Despite modern therapies patients diagnosed with primary brain tumours often have a poor prognosis. Imaging can play an important role in evaluating the disease status of such patients. In addition to the structural information derived from MRI and CT scans, positron emission tomography (PET) provides important quantitative metabolic assessment of brain tumours. This review describes the use of PET with radiolabelled glucose and amino acid analogues to aid in the diagnosis of tumours, differentiate between recurrent tumour and radiation necrosis and guide biopsy or treatment. [(18)F]Fluorodeoxyglucose (FDG) is the tracer that has been used most widely because it has a 2 h half life and can be transported to imaging centres remote from the cyclotron and radiochemistry facilities which synthesise the tracers. The high uptake of FDG in normal grey matter however limits its use in some low grade tumours which may not be visualised. [(11)C] methionine (MET) is an amino acid tracer with low accumulation in normal brain which can detect low grade gliomas, but its short 20 min half life has limited its use to imaging sites with their own cyclotron. The emergence of new fluorinated amino acid tracers like [(18)F]Fluoroethyl-l-tyrosine (FET) will likely increase the availability and utility of PET for patients with primary brain tumours. PET can, further, characterise brain tumours by investigating other metabolic processes such as DNA synthesis or thymidine kinase activity, phospholipid membrane biosynthesis, hypoxia, receptor binding and oxygen metabolism and blood flow, which will be important in the future assessment of targeted therapy.

A meta-analysis on the diagnostic performance of (18)F-FDG and (11)C-methionine PET for differentiating brain tumors

SUMMARY

(18)F-FDG-PET has been widely used in patients with brain tumors. However, the reported sensitivity and specificity of (18)F-FDG-PET for brain tumor differentiation varied greatly. We performed this meta-analysis to systematically assess the diagnostic performance of (18)F-FDG-PET in differentiating brain tumors. The diagnostic performance of (11)C-methionine PET was assessed for comparison. Relevant studies were searched in PubMed/MEDLINE, Scopus, and China National Knowledge Infrastructure (until February 2013). The methodologic quality of eligible studies was evaluated, and a meta-analysis was performed to obtain the combined diagnostic performance of (18)F-FDG and (11)C-methionine PET with a bivariate model. Thirty eligible studies, including 5 studies with both (18)F-FDG and (11)C-methionine PET data were enrolled. Pooled sensitivity, pooled specificity, and area under the receiver operating characteristic curve of (18)F-FDG-PET (n = 24) for differentiating brain tumors were 0.71 (95% CI, 0.63-0.78), 0.77 (95% CI, 0.67-0.85), and 0.80. Heterogeneity was found among (18)F-FDG studies. Subsequent subgroup analysis revealed that the disease status was a statistically significant source of the heterogeneity and that the sensitivity in the patients with recurrent brain tumor was markedly higher than those with suspected primary brain tumors. Pooled sensitivity, pooled specificity, and area under the receiver operating characteristic of (11)C-methionine PET (n = 11) were 0.91 (95% CI, 0.85-0.94), 0.86 (95% CI, 0.78-0.92), and 0.94. No significant statistical heterogeneity was found among (11)C-methionine studies. This meta-analysis suggested that (18)F-FDG-PET has limited diagnostic performance in brain tumor differentiation, though its performance may vary according to the status of brain tumor, whereas (11)C-methionine PET has excellent diagnostic accuracy in brain tumor differentiation.

Molecular imaging in oncology

The major application for PET imaging in clinical practice is represented by cancer imaging and (18)F-FDG is the most widely employed positron emitter compound. However, some diseases cannot be properly evaluated with this tracer and thus there is the necessity to develop more specific compounds. The last decades were a continuous factory for new radiopharmaceuticals leading to an endless list of PET tracers; however, just some of them guard diagnostic relevance in routine medical practice. This chapter describes a selected list of non-FDG PET tracers, basing on their introduction into and impact on clinical practice.

Specific biomarkers of receptors, pathways of inhibition and targeted therapies: clinical applications

A deeper understanding of the role of specific genes, proteins, pathways and networks in health and disease, coupled with the development of technologies to assay these molecules and pathways in patients, promises to revolutionise the practice of clinical medicine. In particular, the discovery and development of novel drugs targeted to disease-specific alterations could benefit significantly from non-invasive imaging techniques assessing the dynamics of specific disease-related parameters. Here we review the application of imaging biomarkers in the management of patients with brain tumours, especially malignant glioma. This first part of the review focuses on imaging biomarkers of general biochemical and physiological processes related to tumour growth such as energy, protein, DNA and membrane metabolism, vascular function, hypoxia and cell death. These imaging biomarkers are an integral part of current clinical practice in the management of primary brain tumours. The second article of the review discusses the use of imaging biomarkers of specific disease-related molecular genetic alterations such as apoptosis, angiogenesis, cell membrane receptors and signalling pathways. Current applications of these biomarkers are mostly confined to experimental small animal research to develop and validate these novel imaging strategies with future extrapolation in the clinical setting as the primary objective.

Shortening the duration of [18F]FDG PET brain examination for diagnosis of brain glioma

PURPOSE

Some patients cannot remain immobile for a long duration of 60 min, which is generally applied in the case of a 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) dynamic positron emission tomography (PET) scan. We investigated the change of the parametric values when the time duration of PET data was shortened.

PROCEDURES

Eight normal subjects and four subjects with brain glioma were studied. The rate values of K(1), k(2), k(3), and K(i) parametric images were computed by changing the time duration from 20 to 60 min, and changes of those parametric values were compared.

RESULTS

The change was 20-30% and 3-5% for k(3) and K(i), respectively, when the scan time was shortened from 60 to 40 min. The ratios of normal and disease regions in k(3) and K(i) values were similar, and contrasts of those images were not changed when the scan time was shortened to 40 min.

CONCLUSIONS

These results demonstrate that the short time duration of [(18)F]FDG PET examination can provide an acceptable estimation of parametric k(3) and K(i) images.

The Clinical Value of PET with Amino Acid Tracers for Gliomas WHO Grade II

The clinical management of adults with low-grade gliomas (LGGs) remains a challenge. There is no curative treatment, and management of individual patients is a matter of deciding optimal timing as well as right treatment modality. In addition to conventional imaging techniques, positron emission tomography (PET) with amino acid tracers can facilitate diagnostic and therapeutic procedures. In this paper, the clinical applications of PET with amino acid tracers ¹¹C-methyl-L-methionine (MET) and ¹⁸F-fluoro-ethyl-L-tyrosine (FET) for patients with LGG are summarized. We also discuss the value of PET for the long-term followup of this patient group. Monitoring metabolic activity by PET in individual patients during course of disease will provide insight in the biological behavior and evolution of these tumors. As such, spatial changes in tumor activity over time, including shifts of hot-spot regions within the tumor, may reflect intratumoral heterogeneity and correlate to clinical parameters.

Glioblastoma detected at the initial stage in its developmental process -case report-

A 73-year-old male presented with a glioblastoma that was detected at the initial stage in the developmental process. He suffered cerebral infarction. Follow-up magnetic resonance (MR) imaging showed no abnormality. Ten months later, he had transient right hemiparesis. Diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) MR imaging showed a hyperintense area in the left frontal lobe. The diagnosis was cerebral infarction and antiplatelet drug treatment was begun. The patient's right hemiparesis subsided. Ten days later, right hemiparesis reappeared. Diffusion-weighted and FLAIR MR imaging showed an enlarged hyperintense area in the left frontal lobe. Three weeks after the onset of right hemiparesis, MR imaging revealed an irregular ring-enhanced mass lesion that had further increased in size. The diagnosis was brain abscess and antibiotic treatment was initiated. However, the lesion did not respond and had further enlarged 5 weeks after the onset of right hemiparesis. The lesion was partially removed and the histological diagnosis was glioblastoma with Ki-67 labeling index of 26%. After surgical treatment, the patient received irradiation of 60 Gy and chemotherapy with temozolomide. Follow-up MR imaging showed regrowth of the tumor and aggravation of edema. The rapid progression of the tumor ultimately resulted in the patient's death 12 months after the onset of right hemiparesis. Diffusion-weighted imaging is a good method for the early detection of glioblastoma.

PET imaging in pediatric neuroradiology: current and future applications

Molecular imaging with positron emitting tomography (PET) is widely accepted as an essential part of the diagnosis and evaluation of neoplastic and non-neoplastic disease processes. PET has expanded its role from the research domain into clinical application for oncology, cardiology and neuropsychiatry. More recently, PET is being used as a clinical molecular imaging tool in pediatric neuroimaging. PET is considered an accurate and noninvasive method to study brain activity and to understand pediatric neurological disease processes. In this review, specific examples of the clinical use of PET are given with respect to pediatric neuroimaging. The current use of co-registration of PET with MR imaging is exemplified in regard to pediatric epilepsy. The current use of PET/CT in the evaluation of head and neck lymphoma and pediatric brain tumors is also reviewed. Emerging technologies including PET/MRI and neuroreceptor imaging are discussed.

Molecular imaging of cancer: evaluating characters of individual cancer by PET/SPECT imaging

The present status of cancer molecular imaging (MI) with nuclear medicine techniques is reviewed, highlighting the Japanese activities in this field. With the progress in MI research, including significant contributions from Japanese studies, it has become possible to noninvasively evaluate various important characters of cancer in clinical patients, such as metabolism, cellular proliferation, tumor hypoxia, and receptor expression. Tumor metabolic information is used for tumor characterization, treatment response evaluation, and prognosis prediction. Hypoxia imaging is used for treatment planning and predicting treatment response. Receptor imaging can be used for the selection of the candidate for receptor-targeted treatment. Various novel probes that can target cancer-associated antigens, various cellular growth factor receptors, tumor angiogenesis, and so on, are under development, aiming for clinical evaluation. Application of radiolabeled ligands for treatment (targeted internal radiation therapy) is another important field in which MI technique can play a critical role. MI, which can deliver the outcome of basic oncological research to the bedside, is essential translational research for improved individualized patient management, and further advances in MI studies are eagerly awaited.

11C-acetate PET in the evaluation of brain glioma: comparison with 11C-methionine and 18F-FDG-PET

PURPOSE

The aim of the study is to retrospectively investigate the usefulness of 11C-acetate (ACE)-positron emission tomography (PET) for evaluation of brain glioma, in comparison with 11C-methionine (MET) and 2-deoxy-2-18F-fluoro-D-glucose (FDG).

PROCEDURES

Fifteen patients with brain glioma referred to initial diagnosis were examined with ACE, MET, and FDG-PET. Five patients had low-grade gliomas (grade II), three had anaplastic astrocytomas (grade III), and seven had glioblastomas (grade IV). PET results were evaluated by visual and semiquantitative analysis. For semiquantitative analysis, the standardized uptake value (SUV) and tumor to contralateral normal gray matter (T/N) ratio were calculated. The sensitivity for detection of high-grade gliomas was calculated using visual analysis.

RESULTS

Sensitivities of ACE, MET, and FDG were 90%, 100%, and 40%, respectively. ACE and MET T/N ratios were significantly higher than that of FDG. ACE and FDG SUV in high-grade gliomas were significantly higher than that in low-grade gliomas. No significant differences were observed using MET.

CONCLUSIONS

ACE PET is a potentially useful radiotracer for detecting brain gliomas and differentiating high-grade gliomas.

Grading of brain glioma with 1-11C-acetate PET: comparison with 18F-FDG PET

The objective of this study is to reevaluate the clinical significance of 1-11C-acetate (ACE) positron emission tomography (PET) in patients with brain glioma, in comparison with 18F-fluorodeoxyglucose (FDG) PET.

METHODS

Ten patients with histologically proven glioma were included in this study. They underwent PET examination with both FDG and ACE on separate days. For ACE PET, 20-min data acquisition was performed just after the administration of 740 MBq of ACE; 10-20-min data were used for the analysis. FDG PET data acquisition for 10 min started 60 min postinjection of 370 MBq of FDG, approximately. Both reconstructed images were converted to standardized uptake value (SUV) images for patient body weight and injected dose. Regions of interest were placed on the tumor and the contralateral cerebral cortex, and SUV and tumor-to-cortex ratio (T/C) were calculated; these values were compared between high- and low-grade gliomas.

RESULTS

SUV and T/C of ACE PET showed significant difference (SUV: 2.63+/-0.46 vs. 1.85+/-0.56, P=.03; T/C: 2.36+/-0.63 vs. 1.14+/-0.36, P=.02). In contrast, FDG PET revealed no significant difference in SUV or T/C between high- and low-grade gliomas (SUV: 7.13+/-4.31 vs. 4.71+/-1.27, P=.31; T/C: 0.98+/-0.55 vs. 0.62+/-0.09, P=.22).

CONCLUSION

This preliminary study revealed that ACE PET is a promising tracer for the grading of brain glioma.

Diagnostic accuracy of 201Thallium-SPECT and 18F-FDG-PET in the clinical assessment of glioma recurrence

PURPOSE

Reliable differential diagnosis between tumour recurrence and treatment-induced lesions is required to take advantage of new therapeutic approaches to recurrent gliomas. Structural imaging methods offer a high sensitivity but a low specificity, which might be improved by neurofunctional imaging. This study aimed to test the hypothesis that incorporation of 18-fluoro-deoxy-glucose positron emission tomography (FDG-PET) increases the accuracy of this differential diagnosis obtained with 201Tl chloride-single-photon emission computed tomography (201Tl-SPECT).

MATERIALS AND METHODS

Seventy-six patients (mean age 47.72 +/- 16.19 years) under suspicion of glioma recurrence, 42% with low-grade and 58% with high-grade lesions, were studied by (201)Tl-SPECT and FDG-PET, reporting results under blinded conditions using visual analysis. Tumour was confirmed by histological confirmation (23 patients) or clinical and structural neuroimaging follow-up (mean of 2.6 years).

RESULTS

This population had a high disease prevalence (72%). Globally, highest sensitivity was obtained using 201Tl-SPECT assessed with MRI (96%) and highest specificity using FDG-PET + MRI (95%). FDG-PET appeared slightly better for confirming tumour recurrence, whereas 201Tl-SPECT was superior for ruling out possible recurrence (disease present in 38% of FDG-PET negative explorations). In the high-grade subgroup, there were no false-positive examinations (specificity: 100%), but sensitivity differed among techniques (201Tl-SPECT : 94%; 201Tl-SPECT + MRI: 97%; FDG-PET + MRI: 83%). In the low-grade subgroup, 201Tl-SPECT + MRI showed highest sensitivity (95%) and lowest posttest negative probability (9%); FDG-PET + MRI offered highest specificity (92%) with a posttest negative probability of 35%.

CONCLUSIONS

FDG-PET does not clearly improve the diagnostic accuracy of (201)Tl-SPECT, which appears to be a more appropriate examination for the diagnosis of possible brain tumour recurrence, especially for ruling it out.

Conventional MRI cannot predict survival in childhood diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) of childhood has a dismal prognosis. Clinical trials of new agents are vital and it is essential that the correct endpoints and disease assessments are chosen. A retrospective review of magnetic resonance imaging (MRI) scanning in a pure population of DIPG was undertaken. Baseline diagnostic MRI findings included; local tumour extension in upper medulla (74%) or midbrain (62%), metastatic disease (3%), basilar artery encasement (82%), necrosis (33%), intratumoural haemorrhage (26%), hydrocephalus (23%) and dorsal exophytic component (18%). Post-treatment MRI scans demonstrated increases in; leptomeningeal metastatic disease (16%), cystic change/necrosis (48%), enhancement (72%) and intratumoural haemorrhage (32%). Response rates were calculated according to both RECIST (4%) and WHO (24%) criteria. No MRI parameter in either the diagnostic or response scans had prognostic significance. We recommend that currently primary endpoints for DIPG clinical trials should be overall or possibly progression free survival and that new advanced functional imaging techniques should be explored as possible surrogate markers for novel therapy activity rather than conventional MRI response criteria.

Molecular Neuroimaging: From Conventional to Emerging Techniques

The use of molecular imaging techniques in the central nervous system (CNS) has a rich history. Most of the important developments in imaging-such as computed tomography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography-began with neuropsychiatric applications. These techniques and modalities were then found to be useful for imaging other organs involved with various disease processes. Molecular imaging of the CNS has enabled scientists and researchers to understand better the basic biology of brain function and the way in which various disease processes affect the brain. Unlike other organs, the brain is not easily accessible, and it has a highly selective barrier at the endothelial cell level known as the blood-brain barrier. Furthermore, the brain is the most complex cellular network known to exist. Various neurotransmitters act in either an excitatory or an inhibitory fashion on adjacent neurons through a multitude of mechanisms. The various neuronal systems and the myriad of neurotransmitter systems become altered in many diseases. Some of the most devastating diseases, including Alzheimer disease, Parkinson disease, brain tumors, psychiatric disease, and numerous degenerative neurologic diseases, affect only the brain. Molecular neuroimaging will be critical to the future understanding and treatment of these diseases. Molecular neuroimaging of the brain shows tremendous promise for clinical application. In this article, the current state and clinical applications of molecular neuroimaging will be reviewed.

Positron emission tomography in oncology: a review

Positron emission tomography is an evolving imaging tool that is becoming increasingly available for use in clinical practice. This overview will look at the current evidence for the use of positron emission tomography in imaging different tumour types and the different radiotracers that are either available or being evaluated in an investigational setting.

Low-grade astroblastoma recurring with extensive invasion

A 17-year-old male presented with morning headache and double vision. Neuroimaging revealed a lobulated enhanced mass lesion with a blurred margin and remarkable peritumoral edema, and high uptake of methionine. The gray, soft, well-circumscribed mass was grossly totally resected. Histological examination showed the tumor cells were well differentiated with the perivascular pseudorosette pattern with broad, non-tapering processes radiating towards a central vessel without anaplastic features such as necrosis and endothelial proliferation. The histological diagnosis was low-grade astroblastoma. Follow-up magnetic resonance imaging demonstrated local recurrence 5 months later. Second surgery was followed by adjuvant radiotherapy and combination chemotherapy. Histological examination disclosed wide invasion by tumor cells into the subpial and perivascular space of the surrounding brain tissue. Follow-up magnetic resonance imaging demonstrated further recurrence around the tumor cavity. Surgical removal followed by six courses of combination chemotherapy (ifosfamide, cisplatin, and etoposide) resulted in complete remission of the tumor. Although gross total resection of astroblastoma usually results in long-term survival, some of these yet unfamiliar tumors may develop a more malignant character.

Thallium-201SPECT assessment in the detection of recurrences of treated gliomas and ependymomas

INTRODUCTION

The aim of this study was to establish the value of thalium-(201) single-photon emission computed tomography ((201)Tl-SPECT) in the detection of recurrences in the follow-up of patients with treated primary neuroepithelial tumours.

MATERIAL AND METHODS

Sixty-three (201)Tl-SPECT were performed in 36 patients with glioma (12 males, mean age of 46 +/- 13 years). All patients underwent surgery and adjuvant radiotherapy (and some of them received chemotherapy). All patients were submitted to morphological neuroimaging techniques as well (and (201) Tl-SPECT). Mean follow-up was 18.3 +/- 14.6 months. Gold standard was based on clinical follow-up, therapeutical decisions (at least 4 months after (201)Tl-SPECT) and imaging features.

RESULTS

Sensitivity and specificity of (201)Tl-SPECT to detect glioma recurrences were 90% and 100% respectively and 93% accuracy. Sensitivity and specificity for high grade tumours, were 100% respectively. Due to 4 false negatives, sensitivity and specificity for low grade gliomas were 78% and 100%. In the positive (201)Tl-SPECT group of patients overall survival was 13.64% at the end of the study. The negative (201)Tl-SPECT group had 84.62% overall survival at the end of the study (p = 0.0003). CONCLUSIONS. (201)Tl-SPECT is a valuable and noninvasive diagnostic procedure to detect recurrence or progression disease for treated gliomas and ependymomas. (201)Tl-SPECT has a good correlation with short term prognosis with excellent diagnostic accuracy.

Diagnostic value of kinetic analysis using dynamic FDG PET in immunocompetent patients with primary CNS lymphoma

PURPOSE

The purpose of this study was to investigate the accumulation of FDG in immunocompetent patients with primary central nervous system (CNS) lymphoma using qualitative and quantitative PET images and to compare baseline with follow-up PET after therapy.

METHODS

Twelve immunocompetent patients with CNS lymphoma were examined. Dynamic emission data were acquired for 60 min immediately following injection of FDG. In seven patients, repeated PET studies were performed after treatment. Applying a three-compartment five-parameter model, K (1), k (2), k (3), k (4), vascular fraction (V ( B )) and cerebral metabolic rate of glucose (CMR(Glc)) were obtained. We evaluated the FDG uptake visually using qualitative and parametric images and quantitatively using parametric images.

RESULTS

A total of 12 lesions were identified in ten patients with newly diagnosed CNS lymphoma. On visual analysis, ten lesions showed an increase on qualitative images, eight showed an increase on K (1) images, 12 showed an increase on k (3) images and ten showed an increase on CMR(Glc) images. On quantitative analysis, k (2), k (3) and CMR(Glc) values of the lesion were significantly different from those of the normal grey matter (p<0.02-0.0005). A total of three lesions were identified in two patients with recurrent tumour. All three lesions showed an increase on qualitative, k (3) and CMR(Glc) images. The K (1), k (2), k (3) and CMR(Glc) values after treatment were significantly different from those obtained before treatment (p<0.04-0.008).

CONCLUSION

Kinetic analysis, especially with respect to k (3), using dynamic FDG PET might be helpful for diagnosis of CNS lymphoma and for monitoring therapeutic assessment.

Early dynamic 201Tl SPECT in the evaluation of brain tumours

OBJECTIVE

To estimate the usefulness of early dynamic 201Tl single photon emission computed tomography (SPECT) studies in distinguishing the histological malignancy of brain tumours.

METHODS

Dynamic 201Tl SPECT was performed for 3 min per scan for 15 min immediately after the administration of 201TlCl in 110 patients with brain tumours (111 lesions). The data obtained each 3 min were used for dynamic SPECT, and the five sets of data obtained were added to acquire static SPECT data. For static SPECT, the static thallium index (STI) was calculated as the ratio of 201Tl uptake in the tumour to that of the contralateral normal brain. The ratio of the 201Tl uptake for each 3 min was defined as the dynamic thallium index (DTI). The dynamic thallium rate (DTR), as a per cent, was calculated as DTR=(DTI for every 3 min)/STI H 100. The five values were approximated as a linear function and the slope (%/min) was calculated.

RESULTS

In static SPECT, there was no significant difference between the STI of malignant tumours (glioblastoma and anaplastic astrocytoma) and that of benign tumours (low-grade glioma, meningioma, pituitary adenoma, neurinoma and haemangioblastoma) (3.7+/-1.5, 5.0+/-3.5, respectively). On dynamic SPECT, DTI increased markedly over 15 min for malignant tumours. In contrast, the DTI of benign tumours increased slightly, steadily or decreased. The slope of the linear functions calculated from the DTRs was much higher in the malignant tumour group than in the benign tumour group (P<0.001).

CONCLUSIONS

We suggest that the performance of 201Tl dynamic SPECT for 15 min is useful for distinguishing malignant brain tumours from benign brain tumours and reduces the examination stress of patients.

Optimization of semi-quantification in metabolic PET studies with 18F-fluorodeoxyglucose and 11C-methionine in the determination of malignancy of gliomas

The treatment of the glioma patient depends on the nature of the lesion and on the aggressiveness of the tumor. The management of gliomas continues to be a challenging task, because morphological neuroimaging techniques do not always differentiate them from nontumoral lesions or high grade tumors from low grade lesions. Positron Emission Tomography (PET) offers the possibility of the in vivo quantitative characterization of brain tumors. Despite decades of useful application of PET in the clinical monitoring of gliomas, no consensus has been reached on the most effective image analysis approach for providing the best diagnostic performance under heavy-duty clinical diagnostic circumstances. The main objective of the present study was to find and validate optimal semi-quantitative search strategies for metabolic PET studies on gliomas, with special regard to the optimization of those metabolic tracer uptake ratios most sensitive in predicting histologic grade and prognosis. 11C-Methionine (11C-Met, n = 50) and/or 18F-Fluorodeoxyglucose (18F-FDG, n = 33) PET measurements were performed in 59 patients with primary and recurrent brain gliomas (22 high grade and 37 low grade tumors) in order to correlate the biological behavior and 11C-Met/18F-FDG uptake of tumors. Data were analyzed by region-of-interests (ROI) methods using standard uptake value calculation. Different ROI defining strategies were then compared with each other for two of the most commonly used metabolic radiotracers, 18F-FDG and 11C-Met, in order to determine their usefulness in grading gliomas. The results were compared to histological data in all patients. Both ANOVA and receiver operating characteristic (ROC) analysis indicated that the performance of 18F-FDG was superior to that of 11C-Met for most of the ratios. 18F-FDG is therefore suggested as the tracer of choice for noninvasive semi-quantitative indicator of histologic grade of gliomas. 11C-Methionine has been suggested as a complimentary tracer, useful in delineating the extent of the tumor. The best diagnostic performance was obtained by calculating the ratio of the peak 18F-FDG uptake of the tumor to that of white matter (p < 0.001; ANOVA). This metabolic tracer uptake ratio is therefore suggested as an easily obtained semi-quantitative PET indicator of malignancy and histological grade in gliomas.

Prognostic value of perfusion-weighted imaging in brain glioma: a prospective study

OBJECT

Biopsy targeting based on MR imaging alone may fail to identify malignant areas in brain gliomas. Considering the differences in relative Cerebral Blood Volume (rCBV) ratios reported among tumour grades, we evaluated whether perfusion-weighted MR imaging (PWI) could usefully implement the routine preoperative imaging by detecting those areas bearing a higher yield for malignancy to guide the stereotactic biopsy or the surgical removal.

CLINICAL MATERIAL AND METHODS

We studied a series of 55 consecutive patients with newly diagnosed brain glioma using both conventional MR imaging and PWI in the preoperative assessment. The pathological diagnosis was established by stereotactic biopsy in 29 cases and by craniotomy in 24 cases. We evaluated the patient survival to detect undergrading.

DISCUSSION

Independent from contrast-enhancement, perfusion-weighted MR imaging improved the target selection in stereotactic biopsy guidance and the removal of malignant areas in tumours amenable to surgery. Particularly sensitive to the perfused part of the tumour as to small regional changes, rCBV maps allowed a better detection of malignant areas. The rCBV ratios correlated significantly to the tumour grade and the final outcome (p < 0.01).

CONCLUSIONS

We found PWI valuable in the preoperative assessment of brain gliomas, discriminating high from low-grade gliomas. PWI can easily be performed on widely available MR imaging systems as part of the routine imaging of gliomas.