表題 Misery perfusion and amyloid deposition in atherosclerotic major cerebral artery disease
要旨Although experimental studies have shown that global cerebral hypoperfusion leads to amyloid deposition in the hemisphere with carotid artery occlusion in rodents, the results of such occurrence are controversial in humans.
Hence, we aim to determine whether global cerebral hypoperfusion leading to decreased blood flow relative to metabolic demand [increased oxygen extraction fraction (OEF),
misery perfusion] is associated with increases in amyloid deposition in the hemisphere with atherosclerotic major cerebral artery disease in patients.
We evaluated the distribution of β-amyloid plaques using positron emission tomography and a [18F]-pyridylbenzofuran derivative (18F-FPYBF-2)
in 13 patients with unilateral atherosclerotic disease of the internal carotid artery (ICA) or middle cerebral artery (MCA) disease and no cortical infarction.
The distribution volume ratio (DVR) of 18F- FPYBF-2 was calculated using dynamic data and Logan graphical analysis with reference tissue and was correlated with the cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and OEF, obtained from 15O-gas PET.
The mean cortical value was calculated as the mean value within the frontal, posterior cingulate, precuneus, parietal, and lateral temporal cortical regions.
Significant reductions in CBF and CMRO2 and increases in OEF were found in the hemisphere ipsilateral to the arterial lesion compared with the contralateral hemisphere.
There was no significant difference for 18F-FPYBF-2 DVR between hemispheres.
The ipsilateral to contralateral ratio of the 18F- FPYBF-2 DVR was increased in 3 patients, while the ipsilateral to contralateral OEF ratio was increased in 4 patients.
The incidence of an increased hemispheric DVR ratio was significantly higher in patients with an increased hemispheric OEF ratio (3/4) than in patients without (0/9) (p<0.02).
Although the 18F- FPYBF-2 DVR in the ipsilateral hemisphere was positively correlated with OEF after adjustment for the 18F- FPYBF-2 DVR in the contralateral hemisphere using multiple regression analysis (p<0.05), the contribution rate of OEF was small (R2=5.5%).
Only one of the 4 patients with an increased hemispheric OEF ratio showed amyloid positivity based on the DVR value. In atherosclerotic major cerebral artery disease, misery perfusion accompanied only small increases of amyloid deposition at best.
Misery perfusion was not associated with amyloid positivity.
表題Increased 18F-FDG accumulation in the tonsils after chemotherapy for pediatric lymphoma: a common physiological phenomenon
要旨Objective: Increased 18F-fluorodeoxyglucose (FDG) uptake in the tonsils after the completion of chemotherapy in patients with lymphoma may be misdiagnosed as tumor recurrence.
This study aimed to investigate the changes in physiological FDG uptake in the tonsils during and after chemotherapy in pediatric patients with lymphoma.
Methods: A total of 47 FDG-PET/CT scans acquired from 13 pediatric patients with lymphoma (before chemotherapy [preC] = 9; during chemotherapy [durC] = 12; within 1 month after the end of chemotherapy [endC] = 11; and after achieving complete response [postC] = 15)
were retrospectively included in this study.
FDG uptake in the palatine tonsils was assessed using maximum standardized uptake value (SUVmax).
The relative size of the palatine tonsils was calculated as the tonsil-pharyngeal ratio (TPR). Serial changes in the SUVmax and TPR were evaluated.
Results: The mean SUVmax was 3.7 ± 1.7, 2.6 ± 0.7, 2.3 ± 0.8, and 6.2 ± 1.6, at the preC, durC, endC, and postC scans, respectively (p < 0.0001);
TPR was 59.0 ± 11.2%, 58.3 ± 9.4%, 54.4 ± 7.9%, and 62.2 ± 12.0% in these groups, respectively, with no significant inter-group differences. TPR and SUVmax showed no correlation.
Conclusions: Increased physiological FDG uptake in the tonsils is commonly observed after the completion of chemotherapy, even in the absence of reactive hypertrophy.
要旨Aim】Esophageal cancer (EK) patients(pts) with focal FDG uptake in bone marrow (BM) misinterpreted as metastasis have been reported.
Vertebral uptake in pts with EK were retrospectively evaluated.
【Methods】 FDG-PET before treatment for EK(n=97) and control pts (n=100) were included. The intensity of Th4-10 (T) and L2-5(L):H(high), M(moderate),
W(weak), balance: T≒L (TL), T>L (Td), T<L (Ld), and pattern: homogeneous (Ho), Heterogeneous (He), Marginal (M), Hot spot (S)) were evaluated.
【Results】Intensity (H/M/W)were classified as follows: (T) 30/59/11%, and (L)18/52/30%. TL/Td/Ld were seen in 56/44/0 (%).
Th(H), Td, and pattern He, M, and S were seen more frequently in EK. Pts with H tended to show Ho pattern, and the M and S patterns were often seen in pts with W.
【Conclusion】Recognizing that pts with EK often show heterogeneous BM uptake is important to avoid misdiagnosis.
演題The relationship among [14C]MeAIB and [3H]MET uptake, gene expression levels of amino acid transporter and proliferative activity assessed by accumulation of [3H]FLT in in-vitro study using human carcinomas
著者Nishii R, Higashi T, Kagawa S, Arimoto M, Kishibe Y, Takahashi M, Yamada S, Saiki M, Arakawa Y, Yamauchi H, Okuyama C, Hojo M, Munemitsu T, Sawada M, Kobayashi M, Kawai K, Nagamachi S, Hirai T, Miyamoto S.
標題 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.
要旨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-PETwere 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.
標題Active bone marrow with focal FDG accumulation mimicking bone metastasis with a case of early esophageal cancer
要旨A 68-year-old man underwent 18F-FDG PET/CT for the staging of esophageal carcinoma discovered by a medical checkup.
Increased focal accumulation in some vertebrae, right humerus, and right femoral bone was noted on FDG-PET, whereas CT showed relatively high attenuation, and MRI showed hypointense lesions on T1- and T2-weighted imaging.
A bone biopsy revealed mildly hypercellular bone marrow in the thoracic spine with FDG accumulation and markedly hypocellular bone marrow in the pelvic bone without an increased uptake.
111InCl scintigraphy showed a similar distribution and confirmed the diagnosis of bone marrow reconversion.