Yukito Maeda

Kagawa University, Japan

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Publications (18)36.51 Total impact

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    ABSTRACT: Hypoxia and its consequences at the molecular level promote tumour progression and affect patient prognosis. One of the main early cellular events evoked by hypoxia is induction of hypoxia-inducible factor 1 (HIF-1) and subsequent upregulation of vascular endothelial growth factor (VEGF). In this study we sought to determine whether hypoxia detected by (18)F-fluoromisonidazole (FMISO) PET accurately reflects the expression of HIF-1α and VEGF in the tumour and can be used as a biomarker of antiangiogenic treatment and as a prognostic factor in newly diagnosed and recurrent malignant gliomas. Enrolled in this study were 32 patients with newly diagnosed glioma and 16 with recurrent glioma of grade III or grade IV. All the patients had undergone FMISO PET preoperatively. The maximum tumour-to-blood FMISO activity ratio (T/Bmax) was used to evaluate the degree of tumour hypoxia and the hypoxic volume (HV) was calculated using a tumour-to-blood FMISO uptake ratio of ≥1.2. Immunohistochemical expressions of HIF-1α and VEGF were evaluated semiquantitatively using the immunoreactivity score (IRS, scores 0 to 12) and the correlation was examined between IRS of HIF-1α or VEGF and FMISO uptake of the tumour (SUVtumour) using navigation-based sampling. Survival was estimated using the Kaplan-Meier method in relation to the T/Bmax and the HV. The T/Bmax and the HV in grade IV gliomas were significantly higher than in grade III gliomas (P < 0.01 and P < 0.01, respectively). Moderate to strong HIF-1α and VEGF expression was observed in the majority of malignant gliomas. The IRS of HIF-1α and VEGF in the tumour were not significantly different between grade III and grade IV gliomas. The IRS of HIF-1α in the tumour did not correlate with the SUVtumour of FMISO in either newly diagnosed or recurrent glioma. There was a significant but weak correlation between the IRS of VEGF and the SUVtumour of FMISO in newly diagnosed glioma, but not in recurrent glioma. The overall survival time in patients with a small HV and a low FMISO T/Bmax was significantly longer than in those with a large HV and a high FMISO T/Bmax (P < 0.01 and P < 0.05, respectively). Preoperative FMISO uptake is significantly correlated with the expression of VEGF in the tumour and might be used as a biomarker of antiangiogenic treatment in newly diagnosed malignant gliomas. However, caution is required because the correlation was weak and there was a large overlap of FMISO uptake between glioma with high and low VEGF expression. In addition, hypoxia determined by FMISO PET appears to be a suitable biomarker for predicting a highly malignant tumour and a poor prognosis in patients with malignant glioma.
    European Journal of Nuclear Medicine 04/2014; · 4.53 Impact Factor
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    ABSTRACT: PURPOSE Although 3'-deoxy-3'-18F-fluorothymidine (FLT) has been used for imaging cell proliferation with PET, it is not incorporated into DNA. A new tracer, 4'-[methyl-11C]-thiothymidine (4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. The purpose of this study was to investigate the feasibility of 4DST PET, compared with FLT PET, for the detection of brain tumors. METHOD AND MATERIALS Thirteen patients with various malignant brain tumors were examined with both 4DST PET and FLT PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of background uptake. PET results were evaluated by visual and semi-quantitative analyses. For semi-quantitative analysis, the standardized uptake value (SUV) and tumor to contralateral normal brain tissue (T/N) ratio were determined by region-of-interest analysis. RESULTS Although both 4DST and FLT showed little uptake in the normal brain, 4DST uptake was somewhat higher than FLT uptake in the normal brain. Both 4DST PET and FLT PET detected all brain tumors. The mean (±SD) value of SUV in the tumor on 4DST PET (3.37±1.93) was significantly higher than that on FLT PET (2.29±2.96) (p<0.01). In contrast, the mean (±SD) value of T/N ratio on FLT PET (10.51±13.65) was significantly higher than that on 4DST PET (3.42±2.23) (p<0.05). A significant correlation was observed between SUV in the tumor on 4DST PET and FLT PET (r=0.91, P<0.001). There was also a significant correlation between T/N ratio on 4DST PET and FLT PET (r=0.95, P<0.001). CONCLUSION These preliminary results indicate that 4DST PET is a potentially useful tracer for proliferation imaging in brain tumors. CLINICAL RELEVANCE/APPLICATION 4DST PET may be a potentially useful tracer for proliferation imaging in brain tumors.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE Although 3'-deoxy-3'-18F-fluorothymidine (FLT) has been used for imaging cell proliferation with PET, it is not incorporated into DNA. A new tracer, 4'-[methyl-11C]-thiothymidine (4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. The purpose of this study was to investigate the feasibility of 4DST PET, compared with FLT PET, for the detection of head and neck cancer. METHOD AND MATERIALS Five patients with head and neck squamous cell carcinoma were examined with both 4DST PET and FLT PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of the surrounding normal tissue. PET results were evaluated by visual and semi-quantitative analyses. For semi-quantitative analysis, the maximal standardized uptake value (SUV) was determined by region-of-interest analysis. RESULTS 4DST uptake in tumors peaked before 3 minutes and reached a constant level at approximately 10 minutes after injection. Physiological uptake in salivary glands of 4DST was stronger than that of FLT. Both 4DST PET and FLT PET detected all head and neck tumors. There was no significant difference between the mean (±SD) value of SUV in the tumor using 4DST PET (8.00±5.03) and FLT PET (10.63±10.29). A significant correlation was observed between SUV in the tumor on 4DST PET and FLT PET (r=0.959, P<0.01). CONCLUSION These preliminary results indicate that 4DST PET is a potentially useful tracer for proliferation imaging in head and neck cancer. CLINICAL RELEVANCE/APPLICATION 4DST PET may be a potentially useful tracer for proliferation imaging in head and neck cancer.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: We evaluated tumor hypoxia using F-fluoromisonidazole (F-FMISO) PET in relation to the expression of hypoxia-inducible factor-1α (HIF-1α) and p53 in patients with head and neck cancer and compared the results with those obtained using 2-deoxy-2-F-fluoro-D-glucose (F-FDG) PET. A total of 28 tumors (23 primary tumors and five metastatic lymph nodes) from 24 patients with newly diagnosed head and neck cancer were examined with F-FMISO PET and F-FDG PET. The F-FMISO PET images were scaled to the venous blood concentration of F-FMISO activity to produce tumor-to-blood (T/B) values. Hypoxia was defined as a region with a T/B ratio greater than or equal to 1.2. The maximum T/B (T/Bmax) and hypoxic volumes were calculated by region-of-interest analysis. For F-FDG PET, the maximum standardized uptake value (SUVmax) and hypermetabolic volume were calculated by region-of-interest analysis. The expressions of HIF-1α and p53 using immunohistochemistry were estimated in tumor tissue samples. A weak correlation was observed between hypoxic volume and T/Bmax (r=0.53, P=0.003) on using F-FMISO PET and between hypermetabolic volume and SUVmax (r=0.38, P=0.046) on using F-FDG PET. The hypoxic volume using F-FMISO PET and hypermetabolic volume using F-FDG PET also showed a weak correlation (r=0.44, P=0.020). The values of F-FMISO hypoxic volume showed a weak correlation with HIF-1α (r=0.40, P=0.037) and p53 (r=0.47, P=0.012) obtained on immunohistochemical examination. This study demonstrates a weak correlation between hypoxic volume measured by F-FMISO PET and expressions of HIF-1α and p53 in head and neck cancer.
    Nuclear Medicine Communications 10/2013; · 1.38 Impact Factor
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    ABSTRACT: BACKGROUND: Quantification of cerebral blood flow (CBF) is important for the understanding of normal and pathologic brain physiology. Positron emission tomography (PET) with H215O (or C15O2) can quantify CBF and apply kinetic analyses, including autoradiography (ARG) and the basis function methods (BFM). These approaches, however, are sensitive to input function errors such as the appearance time of cerebral blood (ATB), known as the delay time. We estimated brain ATB in an image-based fashion to correct CBF by accounting for differences in computed CBF values using three different analyses: ARG and BFM with and without fixing the partition coefficient. METHODS: Subject groups included those with no significant disorders, those with elevated cerebral blood volume, and those with reduced CBF. All subjects underwent PET examination, and CBF was estimated using the three analyses. The ATB was then computed from the differences of the obtained CBF values, and ATB-corrected CBF values were computed. ATB was also estimated for regions of interest (ROIs) of multiple cortical regions. The feasibility of the present method was tested in a simulation study. RESULTS: There were no significant differences in the obtained ATB between the image- and ROI-based methods. Significantly later appearance was found in the cerebellum compared to other brain regions for all groups. In cortical regions where CBF was reduced due to occlusive lesions, the ATB was 0.2 +/- 1.2 s, which was significantly delayed relative to the contralateral regions. A simulation study showed that the ATB-corrected CBF was less sensitive to errors in input function, and noise on the tissue curve did not enhance the degree of noise on ATB-corrected CBF image. CONCLUSIONS: This study demonstrates the potential utility of visualizing the ATB in the brain, enabling the determination of CBF with less sensitivity to error in input function.
    EJNMMI research. 05/2013; 3(1):41.
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    ABSTRACT: Abstract Objective: Traumatic brain injury (TBI) is an epigenetic risk factor for Alzheimer's disease (AD) and amyloid β (Aβ) deposition is observed histopathologically in the traumatized brain. This study was conducted to detect cerebral Aβ deposition using amyloid positron emission tomography (PET) in patients with neuropsychological impairment after TBI. Methods: Twelve patients with post-traumatic neuropsychological impairment (11 men and one woman, age range = 21-78 years) were examined using Pittsburgh Compound B ((11)C-PIB) PET at the chronic stage after TBI (range = 5-129 months). Results: (11)C-PIB was positive in three patients and negative in the other nine patients. There was no correlation between (11)C-PIB deposition and the severity of injury; initial CT findings; elapsed time from the injury; and neuropsychological test scores. Conclusions: The absence of Aβ deposition in many patients with chronic neuropsychological impairment after TBI does not support the premise that Aβ pathology progresses over time in the traumatized brain. Early and sequential (11)C-PIB PET examination may clarify the time course of Aβ deposition in the traumatized brain and the relationship between traumatic brain insult and subsequent neuropsychological impairment.
    Brain Injury 05/2013; · 1.51 Impact Factor
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    ABSTRACT: A 69-year-old man with no history of neurologic or psychiatric disorders underwent C-PiB PET as a healthy volunteer for amyloid imaging study. C-PiB PET images demonstrated an unexpected increased PiB binding in the left frontal region. MR images demonstrated an extra-axial left frontal mass lesion with mild enhancement, highly suggestive of meningioma. There is a limited amount of published information on the detection of meningioma with C-PiB PET.
    Clinical nuclear medicine 04/2013; 38(4):292-3. · 3.92 Impact Factor
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    ABSTRACT: PURPOSE We evaluated the degree of hypoxia in newly diagnosed gliomas using F-18 fluoromisonidazole (FMISO) positron emission tomography (PET) and to compare the results with tumor grade. METHOD AND MATERIALS A total of 30 patients with newly diagnosed gliomas were examined with FMISO PET. Grading of the tumor was performed according to the World Health Organization classification. The FMISO PET images were scaled to the venous blood concentration of FMISO activity to produce tumor-to-blood (T/B) values. Hypoxia was defined as a region with T/B ratio of ≥1.2. For tumor hypoxia visualized with T/B cutoff of, the region of interest was placed over the entire hypoxic region in each slice of the FMISO T/B image. The maximum T/B (T/Bmax) and hypoxic volume were then calculated. RESULTS There was a correlation between FMISO uptake and glioma grade, with all low-grade gliomas (I and II) demonstrating no hypoxia (no pixels with a T/B ratio of ≥1.2) and all high-grade gliomas (III and IV) showing hypoxia. The mean (± SD) FMISO T/Bmax in grades III and IV gliomas was 1.80±0.59 and 2.46±0.44, respectively. Although there was a significant overlap of FMISO uptake, FMISO T/Bmax in grade IV gliomas was significantly higher than that in grade III gliomas (P<0.02). The mean (± SD) hypoxic volume as shown by FMISO uptake with a T/B ratio of ≥1.2 in grade IV glioma (24.45±20.78 cm3) was significantly higher than that in grade III glioma (5.20±9.32 cm3) (P<0.006). CONCLUSION FMISO PET is a potential tracer in assessment of noninvasive tumor grading in newly diagnosed gliomas. CLINICAL RELEVANCE/APPLICATION FMISO PET is a potential tracer in assessment of noninvasive tumor grading in newly diagnosed gliomas.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
  • European Journal of Nuclear Medicine 03/2012; 39(7):1225-6. · 4.53 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the degree of hypoxia in newly diagnosed gliomas using 18F-fluoromisonidazole (FMISO) PET and to compare the results with tumor grade. A total of 30 patients with newly diagnosed gliomas were examined using FMISO PET. Grading of the tumor was performed according to the WHO classification. The FMISO PET images were scaled to the venous blood concentration of FMISO activity to produce tumor-to-blood (T/B) values. Hypoxia was defined as a region with a T/B ratio of at least 1.2, and the maximum T/B (T/Bmax) value was calculated by region-of-interest analysis. There was a correlation between FMISO uptake and glioma grade, with all low-grade gliomas (grades I and II) demonstrating no hypoxia and all high-grade gliomas (grades III and IV) showing hypoxia. The mean T/Bmax in grade IV gliomas was significantly higher than that in grade III gliomas (P<0.02). FMISO PET is a potential tracer in the assessment of noninvasive tumor grading in newly diagnosed gliomas.
    Nuclear Medicine Communications 03/2012; 33(6):621-5. · 1.38 Impact Factor
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    ABSTRACT: A 53-year-old man who presented with mild headache and ophthalmodynia underwent carbon-11 methionine (MET) positron emission tomography (PET). MET PET images demonstrated intense uptake in the periphery of the brain, significantly higher than the physiological uptake in the brain. Biopsy specimens from the pachymeninx indicated hypertrophic pachymeningitis with IgG4-positive plasma cells. After steroid therapy, he became asymptomatic, and a follow-up PET scan showed disappearance of the peripheral brain uptake of MET.
    Clinical nuclear medicine 01/2012; 37(1):108-9. · 3.92 Impact Factor
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    ABSTRACT: The purpose of this study was to compare 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and Tl-201 chloride (Tl) scintigraphy for detection of primary malignant bone and soft-tissue tumors. A total of 40 patients with suspicion of malignant bone and soft-tissue tumors were examined. FDG PET imaging was performed at 1-hour post-FDG injection. Tl planar and single photon emission computed tomography images were acquired 10 minutes (early) and 2 hours (delayed) after injection of Tl. We evaluated FDG and Tl uptake visually and semiquantitatively using standardized uptake value and tumor to contralateral normal tissue ratio on planar images, respectively. Of the 33 patients with malignant tumors, all but 2 liposarcomas showed positive accumulation on FDG PET. However, all 7 benign lesions were also positive on FDG PET. Both early and delayed Tl images were positive for 27 of the 33 malignant tumors. Of the 6 false-negative cases on Tl images, 5 were liposarcomas. Both early and delayed Tl images were negative for 5 of the 7 benign lesions. The sensitivity of FDG PET for detection of primary malignant bone and soft-tissue tumors was 94% and the specificity, 0%. The corresponding values for Tl scintigraphy were 82% and 71%. The mean FDG standardized uptake value in malignant tumors was higher than that in benign lesions, but this difference was not statistically significant. Statistically significant differences were observed between malignant and benign lesions for both early and delayed tumor to contralateral normal tissue ratios. FDG PET was found to be more sensitive than Tl scintigraphy for primary malignant bone and soft-tissue tumors, although it was less specific.
    Clinical nuclear medicine 04/2011; 36(4):290-4. · 3.92 Impact Factor
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    ABSTRACT: This study was conducted to identify the regional neuronal damage occurring in patients with neuropsychological impairment following diffuse traumatic brain injury (TBI) compared with normal control subjects. In addition, measures of the neuropsychological tests were correlated with regional ¹¹C-flumazenil (FMZ) binding potential (BP) reductions to clarify the relationship between cognitive impairment and regional neuronal damage. We performed ¹¹C-flumazenil positron emission tomography (FMZ-PET) studies using three-dimensional stereotactic surface projection (3D-SSP) statistical image analysis in eight diffuse axonal injury (DAI) patients (mean age 29.1 ± 11.1 years, range 19-46 years). All patients underwent assessment with the Wechsler Adult Intellectual Scale-Third Edition (WAIS-III) to evaluate general intelligence. Twenty healthy control subjects (mean age 24.4 ± 2.8 years, range 22-30 years) were also studied to obtain a normal database for 3D-SSP. Group comparisons showed significant regional low FMZ uptake in the bilateral medial frontal gyri, the anterior cingulate gyri, and the thalamus. Individual analysis also showed decreased FMZ uptake in these regions; however, the distribution and extent of low FMZ uptake were different in each individual patient. Full-scale IQ (FIQ) and performance IQ (PIQ) negatively correlated with the degree of FMZ BP reduction (BZR index) in the right thalamus. FIQ, verbal IQ (VIQ), and PIQ also negatively correlated with the BZR index in the left medial frontal gyrus. DAI uniformly induced neuronal damage in the medial frontal cortex and the thalamus, which may be related to underlying cognitive impairments in diffuse TBI patients. Future studies to confirm a common area of focal neuronal damage and a direct correlation with neuropsychological testing may validate the use of FMZ-PET for the functional diagnosis of neuropsychological impairments after TBI.
    Journal of neurotrauma 12/2010; 27(12):2131-8. · 4.25 Impact Factor
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    ABSTRACT: Glioblastoma multiforme (GBM) is characterized by tissue hypoxia associated with resistance to radiotherapy and chemotherapy. To clarify the biological link between hypoxia and tumour-induced neovascularization and tumour aggressiveness, we analysed detailed volumetric and spatial information of viable hypoxic tissue assessed by (18)F-fluoromisonidazole (FMISO) PET relative to neovascularization in Gd-enhanced MRI and tumour aggressiveness by L-methyl-(11)C-methionine (MET) PET in newly diagnosed GBMs. Ten patients with newly diagnosed GBMs were investigated with FMISO PET, MET PET and Gd-enhanced MRI before surgery. Tumour volumes were calculated by performing a three-dimensional threshold-based volume of interest (VOI) analysis for metabolically active volume on MET PET (MET uptake indices of ≥1.3 and ≥1.5) and Gd-enhanced volume on MRI. FMISO PET was scaled to the blood FMISO activity to create tumour to blood (T/B) images. The hypoxic volume (HV) was defined as the region with T/B greater than 1.2. PET and MR images of each patient were coregistered to analyse the spatial location of viable hypoxic tissue relative to neovascularization and active tumour extension. Metabolically active tumour volumes defined using MET uptake indices of ≥1.3 and ≥1.5 and the volumes of Gd enhancement showed a strong correlation (r = 0.86, p < 0.01 for an index of ≥1.3 and r = 0.77, p < 0.05 for an index of ≥1.5). The HVs were also excellently correlated with the volumes of Gd enhancement (r = 0.94, p < 0.01). The metabolically active tumour volumes as defined by a MET uptake index of ≥1.3 and the HVs exhibited a strong correlation (r = 0.87, p < 0.01). On superimposed images, the metabolically active area on MET PET defined by a MET uptake index of ≥1.3 was usually larger than the area of the Gd enhancement and about 20-30% of the MET area extended outside the area of the enhancement. On the other hand, the surface area of viable hypoxic tissue with a T/B cutoff of ≥1.2 on FMISO PET did not substantially differ from the area of the Gd enhancement. The volumetric analysis demonstrates that the viable hypoxic tissue assessed by FMISO PET is related to the neovascularization in Gd-enhanced MRI and the tumour aggressiveness by MET PET in newly diagnosed GBMs. The spatial analysis shows that the metabolically active tumour may be substantially underestimated by Gd-enhanced MRI. Complementary use of MET and FMISO to Gd-enhanced MRI may improve the understanding of tumour biology and lead to the most efficient delineation of tumour volume and treatment strategy.
    European Journal of Nuclear Medicine 11/2010; 38(3):441-50. · 4.53 Impact Factor
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    ABSTRACT: The diagnosis of primary central nervous system lymphoma (PCNSL) in immunocompetent patients with atypical magnetic resonance (MR) findings such as disseminated lesions or no (non-enhancing) lesion is sometimes difficult because of mimicking other tumorous and non-tumorous diseases. Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) and (11)C-methionine (MET) can measure the glucose and amino acid metabolism in the lesions and may provide useful information for diagnosing PCNSL in patients with such subtle MR findings. We performed PET studies with FDG and MET in 17 histologically proven PCNSL and compared the uptake of FDG and MET qualitatively and quantitatively in the tumors between 12 typical and 5 atypical MR findings. All typical PCNSL showed strong uptake of FDG and MET; however, visual analysis of FDG and MET uptake in atypical PCNSL was not very useful for finding lesions in the brain. Semiquantitative FDG and MET uptake values (SUVmax) and quantitative FDG influx rate constant (K ( i )) in the tumors are significantly lower in atypical PCNSL compared with those in typical PCNSL. These values obtained in the lesions with atypical MR findings were also not useful for differentiating PCNSL from other tumorous and non-tumorous diseases. The k (3) values evaluated by FDG kinetic analysis in atypical PCNSL were similar to those obtained in typical PCNSL. Visual analysis of FDG and MET uptake in atypical PCNSL was not useful for finding the lesions in the brain. Semiquantitative and quantitative values obtained in the lesions with atypical MR findings were also not useful for differentiating PCNSL from other tumorous and non-tumorous diseases. The k (3) values evaluated by FDG kinetic analysis in atypical PCNSL may provide valuable information in the diagnosis of PCNSL.
    Annals of Nuclear Medicine 04/2010; 24(5):335-43. · 1.41 Impact Factor
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    ABSTRACT: PURPOSE We investigated the feasibility of 3'-deoxy-3'-18F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of head and neck squamous cell carcinoma (HNSCC), in comparison with 2-deoxy-2-18F-fluoro-D-glucose (FDG) PET, and determined the degree of correlation between the two radiotracer and proliferative activity as indicated by the Ki-67 index. METHOD AND MATERIALS A total of 43 patients with newly diagnosed HNSCC were examined with FLT PET and FDG PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semi-quantitative analysis, the maximal standardized uptake value (SUV) was calculated. RESULTS All 43 HNSCC showed focally increased uptake of both FLT and FDG. The mean (±SD) SUV for FLT (5.7±3.0) was significantly lower than that for FDG (10.9±4.9; p<0.01). The mean (±SD) FLT SUV in poorly differentiated tumors (6.5±3.1) was significantly higher than that in well differentiated tumors (4.2±2.1; p<0.04). The mean (±SD) FDG SUV in poorly (12.7±4.8) and moderately (11.5±4.6) differentiated tumors were also significantly higher than that in well differentiated tumors (7.4±3.5; p<0.004). There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV. CONCLUSION FLT PET showed as high a sensitivity as FDG PET for the detection of HNSCC, although uptake of FLT in HNSCC was significantly lower than that of FDG. Neither of the two radiotracers used reflected proliferative activity. CLINICAL RELEVANCE/APPLICATION FLT PET showed as high a sensitivity as FDG PET for the detection of HNSCC, although uptake of FLT in HNSCC was significantly lower than that of FDG.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009
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    ABSTRACT: PURPOSE F-18 FDG (FDG) PET has been used as a promising tool to diagnose primary central nervous system lymphoma (PCNSL) because the tumor shows very high FDG accumulation. Although C-11 methionine (MET) PET has been reported to be useful for evaluating various brain tumors, the role of MET PET in PCNSL is unclear. We compared the uptake of MET and FDG in patients with PCNSL. METHOD AND MATERIALS Ten lesions in 8 immunocompetent patients with PCNSL were examined. All patients underwent PET with MET (15 min p.i.) and FDG (60 min p.i.). PET results were evaluated by visual and semi-quantitative analysis. For semi-quantitative analysis, the standardized uptake value (SUV) for tumor and tumor to contralateral normal brain tissue (T/N) ratio were determined by region-of-interest analysis. RESULTS All 10 lesions showed focally increased uptake of both MET and FDG. The mean (±SD) MET SUV in the contralateral normal brain tissue (1.3±0.2) was significantly lower than that of FDG SUV (6.0±1.9; p<0.02). The mean (±SD) MET SUV in the PCNSL (3.5±1.6) was significantly lower than that of FDG SUV (14.1±5.7; p<0.006). There was no significant difference between MET T/N ratio (2.6±1.1) and FDG T/N ratio (2.6±1.3). CONCLUSION MET PET showed as high a sensitivity as FDG PET for the detection of PCNSL, although uptake of MET in PCNSL was significantly lower than that of FDG. CLINICAL RELEVANCE/APPLICATION MET PET showed as high a sensitivity as FDG PET for the detection of PCNSL, although uptake of MET in PCNSL was significantly lower than that of FDG.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009
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    ABSTRACT: Prognosis of germinoma arising in the basal ganglia or thalamus is worse compared to that in the pineal or suprasellar region. One of the reasons for poor prognosis is the difficulty in evaluating the efficacy of treatment by conventional neuroimaging tools. PET STUDIES: The usefulness of (11)C-methionine (MET) positron emission tomography (PET) in monitoring the biological nature of brain tumors has been proved in glioma patients. Herein, we describe MET-PET findings in three cases of germinomas in the basal ganglia or thalamus and discuss the use of MET-PET in the assessment of treatment response and residual tumor for the next treatment strategy. The patients showed transient increase of MET uptake in the lesions after the initial treatment. Although we did not perform histological verification, MET- PET findings suggested that active tumor cells were still alive in the lesions after the initial treatment. MET uptake gradually decreased during the course of intensive therapy in these patients. MET-PET also revealed germinoma invasion in the brain before discernible signal abnormality or mass lesion in conventional magnetic resonance images in two patients. Further studies including histological verification and long-term follow-up might validate the use of MET-PET in monitoring the treatment efficacy and evaluation of active residual tumor after the treatment. Until we understand what MET uptake truly represents, treatment strategy based on MET uptake must be carefully designed to prevent overtreatment and resultant complications.
    Child s Nervous System 04/2009; 25(7):845-53. · 1.24 Impact Factor