The reproducibility of MTV and TLG of soft tissue tumors calculated by FDG-PET: Comparison between the lower limit by the fixed value SUV 2.5 and that value by 30% of SUVmax.

PURPOSE: We evaluated the reproducibility calculating volume-based FDG-PET/CT parameters, i.e., metabolic tumor volume (MTV) and total lesion glycolysis (TLG), in soft tissue tumors. MATERIALS AND METHODS: Fifty-three cases with soft tissue tumors were analyzed retrospectively. The conditions determining the lower limit of MTV were fixed value SUV 2.5 or 30% of SUVmax. To investigate the agreement of the measurements by two radiologists, %difference, the correlation coefficients and Bland-Altman plot were analyzed. We compared these parameters in both intra- and inter-operator for evaluating the agreement in the measurements. RESULTS: The values of % difference were excellent, 0.2-3.5%, in the intra-operator in all calculated volume-based parameters. In both inter- and intra-operator analysis, the values of % differences were lower in the parameters calculated by SUV 2.5 fixed value as a lower threshold compared with those calculated by 30% of SUVmax as a lower threshold. The correlation coefficient in MTV30% for inter-operator were 0.84 or 0.87, those were lower than values by the intra-operator evaluation. Nevertheless, the correlation coefficients were higher than 0.84 in every parameter. Particularly, correlation coefficient in the parameters calculated by SUV 2.5 fixed value was better than those calculated by 30% of SUVmax. The Bland-Altman plot analysis showed good agreement for all parameters, particularly in the intra-operator examinations. However, in the inter-operator study, some variances were noted in every condition. CONCLUSION: In conclusion, the reproducibility of measuring volume-based FDG-PET/CT parameters of soft tissue tumors was good, particularly, in the measurement by fixed lower limit value SUV 2.5 in the intra-operator.

Unilateral GPi-DBS Improves Ipsilateral and Axial Motor Symptoms in Parkinson's Disease as Evidenced by a Brain Perfusion Single Photon Emission Computed Tomography Study.

Introduction: Deep brain stimulation (DBS) is an effective treatment for advanced Parkinson's disease (PD) with the targeting bilateral subthalamic nucleus or globus pallidus internus (STN or GPi-DBS). So far, detailed studies on the efficacy of unilateral STN-DBS for motor symptoms have been reported, but few studies have been conducted on unilateral GPi-DBS. Materials and Methods: Seventeen patients with Parkinson's disease (PwPD) who underwent unilateral GPi-DBS were selected. We conducted comparison analyses between scores obtained 6-42 months pre- and postoperatively using the following measurement tools: the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III, the Hoehn and Yahr stage, the presence/absence of dyskinesia, Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), Geriatric Depression Scale (GDS), levodopa equivalent dose (LED), and cerebral blood flow by single photon emission computed tomography (SPECT). Patient backgrounds were compared between four cohorts with favorable (good responders, ≥50% improvement) and unfavorable (poor responders, <50% improvement) postoperative outcome. Results: Significant improvement was observed postoperatively in the following: total MDS-UPDRS Part III scores during the off period, contralateral scores, ipsilateral scores, and axial scores. Similarly, the Hoehn and Yahr stages during the off period, and GDS also showed significant decrease. In contrast, LED, MMSE, and FAB remained unchanged while the number of patients who scored positive for dyskinesia decreased by 40%. Abnormal cerebral blood flow preoperatively seen in the cerebral cortex had normalized in the total score-based good responder cohort. In the ipsilateral score-based good responder cohort, cerebral blood flow increased in the contralateral frontal lobe including in the premotor cortex, contralateral to the DBS. Compared to the poor responders, postoperative good responders demonstrated significantly higher preoperative MMSE scores. Discussion: Unilateral GPi-DBS therapy was effective in improving contralateral, ipsilateral, and axial motor symptoms of patients with advanced PD; in particular, it was found to be especially beneficial in PwPD whose cognitive function was unimpaired; the treatment efficacy rivaled that of bilateral counterparts up till at least 6 months postoperatively. Finally, normalization of preoperative abnormalities in cerebral blood flow and increased cerebral blood flow in the contralateral frontal lobe indicated the beneficial potential of this therapy on ipsilateral motor symptoms.

Comparison of 18F-FDG PET/CT and 67Ga-SPECT for the diagnosis of fever of unknown origin: a multicenter prospective study in Japan.

OBJECTIVE: The aim of this multicenter prospective study was to compare the sensitivity of 18F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) with that of 67Ga single photon emission computed tomography (SPECT) for the identification of the site of greatest importance for the final diagnosis of the cause of fever of unknown origin (FUO). METHODS: The study participants consisted of patients with an axillary temperature ≥ 38.0 °C on ≥ 2 occasions within 1 week, with repeated episodes for ≥ 2 weeks prior to providing consent, and whose final diagnosis after undergoing specific examinations, including a chest-to-abdomen CT scan, was uncertain. All the patients underwent FDG-PET/CT imaging first, followed by 67Ga-SPECT imaging within 3 days. The results of the FDG-PET/CT and 67Ga-SPECT examinations were reviewed by the central image interpretation committee (CIIC), which was blinded to all other clinical information. The sensitivities of FDG-PET/CT and 67Ga-SPECT were then evaluated with regard to identifying the site of greatest importance for a final diagnosis of the cause of the fever as decided by the patient's attending physician. The clinical impacts (four grades) of FDG-PET/CT and 67Ga-SPECT on the final diagnosis were evaluated. RESULTS: A total of 149 subjects were enrolled in this study between October 2014 and September 2017. No adverse events were identified among the enrolled subjects. Twenty-one subjects were excluded from the study because of deviations from the study protocol. Among the 128 remaining subjects, a final diagnosis of the disease leading to the appearance of FUO was made for 92 (71.9%) subjects. The final diagnoses in these 92 cases were classified into four groups: noninfectious inflammatory disease (52 cases); infectious disease (31 cases), malignancy (six cases); and other (three cases). These 92 subjects were eligible for inclusion in the study's analysis, but one case did not meet the PET/CT image acquisition criteria; thus, PET/CT results were analyzed for 91 cases. According to the patient-based assessments, the sensitivity of FDG-PET/CT (45%, 95% CI 33.1-58.2%) was significantly higher than that for 67Ga-SPECT (25%, 95% CI 15.5-37.5%) (P = 0.0029). The clinical impact of FDG-PET/CT (91%) was also significantly higher than that for 67Ga-SPECT (57%, P < 0.001). CONCLUSIONS: FDG-PET/CT showed a superior sensitivity to 67Ga-SPECT for the identification of the site of greatest importance for the final diagnosis of the cause of FUO.

The development of new method to differentiate between Dementia with Lewy bodies and Alzheimer's disease by cerebral perfusion SPECT-comparison to CIScore.

PURPOSE: The Cingulate Island Sign score (CIScore) by rCBF SPECT is used in the differentiation between Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) but has some false-positive AD cases. To resolve the problem, we developed new differential diagnosing method incorporating occipital lobe and para-hippocampal rCBF. MATERIALS AND METHODS: In 27 DLB and 31 AD cases undertaken Tc-99 m-ECD SPECT, we evaluated the mean Z score in the bilateral superior, middle, inferior occipital gyri, cuneus, amygdala, hippocampus, and para-hippocampus. One criterion of DLB was defined as the case with CIScore lower than 0.27. The other criteria were the cases of following either or both two conditions were satisfied. (1) The number of occipital gyri with mean Z score higher than 1 is three or more. (2) The number of hippocampal regions with mean Z score higher than 1 is one or less. We compared the differential diagnostic ability among these four criterions. RESULTS: The diagnostic accuracy by CIscore was 69% and that of the occipital gyri analysis 84%, para-hippocampal regions analysis 76% and combined occipital gyri and para-hippocampal regions analysis 93%. CONCLUSION: The new method by combined rCBF analysis of occipital gyri and para-hippocampal regions showed best diagnostic ability in differentiating DLB from AD.

[Sensitivity and specificity of combined use of Ala score and CIScore in the diagnosis of dementia with Lewy bodies].

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are two major types of dementia. Due to shared signs and symptoms, accurate diagnosis of these dementia subtypes is a clinical challenge. We assessed the sensitivity and specificity of the combined use of neuropsychological testing and brain imaging data for the differential diagnosis of these conditions. The study population included 77 patients with either AD or DLB. Ala score was calculated from Mini-Mental State Exam subscores, and the cingulate island sign score (CIScore) was obtained from image analysis of brain perfusion single-photon emission computed tomography. Correlation between Ala score and CIScore values was observed in the subgroup of patients aged ≤79 years (r = 0.485, P = 0.002), and the scatter plot revealed that 70% of DLB patients were within the range of cut-off values for DLB. In the group aged ≥80 years, there was poor correlation between the Ala and CIScores (r = 0.285, P = 0.083), the average CIScore exceeded the cut-off value, and the scatter plot showed lower sensitivity, illustrating the challenge of discriminating AD from DLB in an older patient population. The concurrent use of Ala score and CIScore enhanced the specificity and the area under the curve in both subgroups, indicating the improved ability of these tests to aid in the differential diagnosis of AD from DLB. Our findings suggest that the use of these methodologies in routine medical practice may increase the sensitivity and specificity of the diagnosis of dementia subtypes.

Impact of short-acting loop diuretic doses and cardiac sympathetic nerve abnormalities on outcomes of patients with reduced left ventricular function.

Recent studies reported that high doses of short-acting loop diuretics are associated with poor outcomes in patients with heart failure (HF). Short-acting loop diuretics have been shown to activate the renin-angiotensin system (RAS) and have no favorable effects on cardiac sympathetic nervous system (SNS) activity. The goal of this study is to investigate the relationship between daily doses of furosemide and the outcomes of patients with left ventricular dysfunction (LVD) from the viewpoint of cardiac SNS abnormalities using iodine-123-labeled metaiodobenzylguanidine (l-MIBG) myocardial scintigraphy.We enrolled 137 hospitalized patients (62.5 ±â€Š14.2 years old, 103 men) with LVEF < 45% who underwent l-MIBG myocardial scintigraphy. A delayed heart-to-mediastinum ratio (delayed HMR) was assessed using l-MIBG scintigraphy. Cardiac events were defined as cardiac death or re-hospitalization due to the deterioration of HF. Cox proportional hazard analysis was used to identify predictors of cardiac events.Cardiac events occurred in 57 patients in a follow-up period of 33.1 ±â€Š30 months. In a multivariate Cox proportional hazard analysis, delayed HMR and furosemide doses were identified as independent predictors of cardiac events (P = .0042, P = .033, respectively). Inverse probability of treatment weighting Cox modeling showed that the use of furosemide (≥40 mg /day) was associated with cardiac events with a hazard ratio of 1.96 (P = .003). In the Kaplan-Mayer analysis, the cardiac event-free survival rate was significantly lower in patients treated with high doses of furosemide (≥60 mg/day vs 40-60 mg/day vs <40 mg/day, the Log-rank test P < .0001). In a receiver-operating characteristic (ROC) analysis, the cut-off value for cardiac events was 40 mg/day of furosemide. The cardiac event-free rate was significantly lower in patients with delayed HMR <1.8 (median value) and receiving furosemide ≥40 mg/day than in other patients (the Log-rank test P < .0001). Significant differences in cardiac event rates according to furosemide doses among patients with delayed HMR <1.8 were observed among patients without ß-blocker therapy (P = .001), but not among those with ß-blocker therapy (P = .127).The present results indicate that a relationship exists between higher doses of furosemide and poor outcomes. The prognosis of HF patients with severe cardiac SNS abnormalities receiving high-dose short-acting loop diuretics is poor.

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.

Do TSH, FT3, and FT4 Impact BAT Visualization of Clinical FDG-PET/CT Images?

Objective: We retrospectively analyzed activated BAT visualization on FDG-PET/CT in patients with various conditions and TH levels to clarify the relationships between visualization of BAT on FDG-PET/CT and the effect of TH. Methods: Patients who underwent clinical FDG-PET/CT were reviewed and we categorized patients into 5 groups: (i) thyroid hormone withdrawal (THW) group; (ii) recombinant human thyrotropin (rhTSH) group; (iii) hypothyroidism group; (iv) hyperthyroidism group; and (v) BAT group. A total of sixty-two FDG-PET/CT imaging studies in fifty-nine patients were performed. To compare each group, gender; age; body weight; serum TSH, FT3, and FT4 levels; and outside temperature were evaluated. Results: No significant visualization of BAT was noted in any of the images in the THW, rhTSH, hypothyroidism, and hyperthyroidism groups. All patients in the BAT group were in a euthyroid state. When the BAT-negative and BAT-positive patient groups were compared, it was noted that the minimum and maximum temperature on the day of the PET study and maximum temperature of the one day before the PET study were significantly lower in BAT-positive group than in all those of other groups. Conclusions: Elevated TSH condition before RIT, hyperthyroidism, or hypothyroidism did not significantly impact BAT visualization of clinical FDG-PET/CT images.

Prediction of Posthepatectomy Liver Failure Proposed by the International Study Group of Liver Surgery: Residual Liver Function Estimation With 99mTc-Galactosyl Human Serum Albumin Scintigraphy.

PURPOSE: The International Study Group of Liver Surgery (ISGLS) proposed a definition and grading system for posthepatectomy liver failure (PHLF). We evaluated the usefulness of residual liver function estimation using Tc-galactosyl human serum albumin (Tc-GSA) for the prediction of PHLF. METHODS: Patients with liver tumors (n = 136) and scheduled for hepatectomy underwent Tc-GSA scintigraphy. Based on their imaging data, the maximal GSA removal rate (GSA-Rmax)was calculated using multicompartment analysis. We also calculated GSA-Rmax in the predicted residual liver (GSA-RL) whose volume was determined on computed tomography (CT) scans. We compared the age, sex, 15-minute indocyanine green retention rate; albumin, bilirubin, hyaluronic acid, and type 4 collagen levels; the Child-Pugh classification; residual liver volume; residual liver percentage; GSA-Rmax; and GSA-RL in patients with and without PHLF. Univariate and multivariate logistic analyses were used for statistical assessments. RESULTS: Of 136 patients, 17 (12.5%) met the ISGLS criteria for PHLF (ISGLS-PHLF). There was a statistically significant difference in the age, albumin level, Child-Pugh classification, residual liver volume, residual liver percentage, GSA-Rmax, and GSA-RL between patients with and without PHLF. Based on multivariate analysis, GSA-RL and the residual liver volume were significant independent predictors of ISGLS-PHLF (P = 0.004 and P = 0.038, respectively). The odds ratio was 149423 for GSA-RL and 1.003 for the residual liver volume. CONCLUSIONS: GSA-RL calculated using Tc-GSA scintigraphy was the most useful independent predictor for ISGLS-PHLF.

Multiple 18F-Fluorodeoxyglucose Positron Emission Tomography Scans Showing Progression of Abdominal Aortic Aneurysm: A Case Report.

Although the precise mechanisms underlying the pathogenesis of abdominal aortic aneurysm (AAA) remain unclear, aortic wall inflammation has been implicated in AAA development. Several studies have reported the use of fluoro-deoxyglucose (F-FDG)/positron emission tomography (PET) to assess the nature of AAA.We present a case of 77-year-old Japanese male with juxta-anastomotic AAA who was followed up with multiple F-FDG-PET/CT scans over 7 years. The scans revealed chronological changes in aortic wall inflammation leading to progress and eventual rupture.This case supports a notion that aortic wall inflammation plays a role in AAA progression and rupture.

PR Prolongation and Cardiac 123I-MIBG Uptake Reduction in Parkinson's Disease.

BACKGROUND: Cardiac 123I-metaiodobenzylguanidine scintigraphy (MIBG) previously demonstrated an uptake reduction in patients with Parkinson's disease (PD). However, epidemiologic research showed that electrocardiography (ECG) abnormalities occurred prior to motor signs in PD. Here we investigated whether the electrical conduction system of the heart was impaired in PD. METHODS: Clinical features, ECG and MIBG parameters were analyzed in 191 patients with PD, 42 with multiple system atrophy (MSA) and 124 normal controls (NL). RESULTS: The PR interval was significantly longer in patients with PD than in NL. The PR interval was significantly negatively correlated with early and delayed heart-to-mediastinum ratios in MIBG scintigraphy in PD and MSA patients. In 19 PD patients with PR prolongation, 17 patients also had abnormal MIBG findings, and the other 2 showed normal MIBG. CONCLUSIONS: The PR prolongation must show some sympathetic system abnormality because it is mainly controlled by the sympathetic nervous system. PR prolongation supports the objective biomarker value of MIBG for PD diagnosis.

Hypometabolism of watershed areas of the brain in HTLV-1-associated myelopathy/tropical spastic paraparesis.

In previous studies of human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), areas of slow blood flow in the spinal cord were related to pathological changes. While the pathological changes in the brain are milder than those in the spinal cord, they are also more significant in sites with slow blood flow. In this study, we investigated brain glucose metabolism in slow blood flow areas using fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET). Clinical features and brain (18)F-FDG-PET parameters were analyzed in six patients with HAM/TSP. For comparison of PET data, eight healthy volunteers were enrolled as normal controls (NLs). Glucose metabolism in the watershed areas of the middle and posterior cerebral arteries, as compared with that in the occipital lobes as a control, was significantly lower in HAM/TSP patients than in NLs. This result confirmed the relationship between slow blood flow areas and hypometabolism in HAM/TSP, and is consistent with previous findings that pathological changes are accentuated in sites with slow blood flow.

Development of radioiodine-labeled 4-hydroxyphenylcysteamine for specific diagnosis of malignant melanoma.

INTRODUCTION: A specific diagnosis for melanoma is strongly desired because malignant melanoma has poor prognosis. In a previous study, although radioiodine-125-labeled 4-hydroxyphenyl-L-cysteine ((125)I-L-PC) was found to have good substrate affinity for tyrosinase enzyme in the melanin metabolic pathway, (123/131)I-L-PC had insufficient substrate affinity for tyrosinase to diagnose melanoma. In this study, we synthesized 4-hydroxyphenylcysteamine (4-PCA) and developed a novel radioiodine-125-labeled 4-hydroxyphenylcysteamine ((125)I-PCA) to increase affinity for the melanin biosynthesis pathway. METHODS: 4-PCA was separated with 2-hydroxyphenylcysteamine (2-PCA), which is an isomer of 4-PCA, and was examined using melting point, proton nuclear magnetic resonance, mass spectrometry and elemental analysis. (125)I-PCA was prepared using the chloramine-T method under no-carrier added conditions. We performed biodistribution experiments using B16 melanoma-bearing mice using (125)I-PCA, (125)I-L-PC, (125)I-α-methyl-L-tyrosine, (123)I-m-iodobenzylguanidine and (67)Ga-citrate. In vitro assay was performed with B16 melanoma cells, and affinity for tyrosinase, DNA polymerase and amino acid transport was evaluated using phenylthiourea, thymidine, ouabine and L-tyrosine inhibitor. In addition, partition coefficients of (125)I-PCA were evaluated. RESULTS: In the synthesis of 4-PCA, analysis values did not differ between calculated and reported values, and 4-PCA was separated from 2-PCA at high purity. In biodistribution experiments, (125)I-PCA was accumulated and retained in B16 melanoma cells when compared with (125)I-L-PC. (125)I-PCA showed the highest values at 60 min after radiotracer injection in melanoma-to-muscle ratios, melanoma-to-blood ratios and melanoma-to-skin ratios. Accumulation of (125)I-PCA was significantly inhibited by phenylthiourea and thymidine. Partition coefficients of (125)I-PCA were lower than those of N-isopropyl-p-[(123)I]iodoamphetamine and were not significantly different from (125)I-L-PC. CONCLUSIONS: (125)I-PCA is a better substrate for tyrosinase and DNA polymerase and has higher uptake and longer retention in B16 melanoma cells when compared with (125)I-L-PC. Therefore, (123/131)I-PCA has good potential for diagnosis for malignant melanoma. ADVANCE IN KNOWLEDGE: (125)I-PCA will be a specific diagnosis tool for malignant melanoma. IMPLICATIONS FOR PATIENT CARE: (123/131)I-PCA has good potential for the diagnosis of malignant melanoma when compared with other SPECT tracers, as well as anti-melanoma chemotherapeutic drugs.

[A case of neurolymphomatosis: peripheral neuropathy induced by diffuse large B-cell lymphoma without any abnormal accumulation observed on early positron emission tomography-computed tomography].

A 64-year-old woman with diffuse large B-cell Lymphoma (DLBCL) complained of double vision and pain sensation in her limbs after eight cycles of chemotherapy. F-fluorodexyglucose-positron emission tomography (FDG-PET) 7 days after the onset of double vision showed no abnormal accumulation and confirmed remission of DLBCL according to the international criteria. However, she developed limb weakness and severe paresthesia. The second FDG-PET 41 days after onset showed increased uptake at the both the brachial and lumbar plexuses, suggesting neurolymphomatosis. Although FDG-PET appears to be a highly sensitive diagnostic method for neurolymphomatosis, it is sometimes difficult to detect neurolymphomatosis in early diagnose, such as with this case. Therefore, multiple examinations are necessary to determine neurolymphomatosis.

Diagnostic usefulness of an amino acid tracer, α-[N-methyl-(11)C]-methylaminoisobutyric acid ( (11)C-MeAIB), in the PET diagnosis of chest malignancies.

OBJECTIVES: Although positron emission tomography (PET) using [(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) is established as one of the first-choice imaging modalities in the diagnosis of chest malignancies, there are several problems to solve in clinical practice, such as false positive uptake in inflammatory diseases. The aim of this study was to evaluate the clinical usefulness of an amino acid tracer, α-[N-methyl-(11)C]-methylaminoisobutyric acid ((11)C-MeAIB), in the diagnosis of chest malignancies, in combination with (18)F-FDG. SETTING: Fifty-nine cases (57 patients, 66 ± 12 years old) who consulted to our institution for the wish to receive differential diagnosis of chest diseases were included. Purpose of the studies were as follows: differential diagnosis of newly developed lung nodules, n = 22; newly developed mediastinal lesions, n = 20; and both, n = 17 (including lung cancer: n = 19, lymphoma: n = 1, other cancers: n = 2, sarcoidosis: n = 15, non-specific inflammation: n = 18, other inflammatory: n = 4, respectively). Whole-body static PET or PET/CT scan was performed 20 and 50 min after the IV injection of (11)C-MeAIB and (18)F-FDG, respectively. RESULTS: (11)C-MeAIB uptake of malignant and benign lesions was statistically different both in pulmonary nodules (p < 0.005) and in mediastinal lesions (p < 0.0005). In visual differential diagnosis, (11)C-MeAIB showed higher results (specificity: 73 %, accuracy: 81 %), compared to those in (18)F-FDG (60, 73 %, respectively). In cases of sarcoidosis, (11)C-MeAIB showed higher specificity (80 %) with lower uptake (1.8 ± 0.7) in contrast to the lower specificity (60 %) with higher uptake of (18)F-FDG (7.3 ± 4.5). CONCLUSIONS: (11)C-MeAIB PET/CT was useful in the differential diagnosis of pulmonary and mediastinal mass lesions found on CT. (11)C-MeAIB PET or PET/CT showed higher specificity than that of (18)F-FDG PET/CT in differentiating between benign and malignant disease. Our data suggest that the combination of (18)F-FDG and (11)C-MeAIB may improve the evaluation of chest lesions, when CT and (18)F-FDG PET/CT are equivocal.

The usefulness of (18)F-FDG PET/MRI fusion image in diagnosing pancreatic tumor: comparison with (18)F-FDG PET/CT.

PURPOSE: This study aimed at demonstrating the feasibility of retrospectively fused (18)F FDG-PET and MRI (PET/MRI fusion image) in diagnosing pancreatic tumor, in particular differentiating malignant tumor from benign lesions. In addition, we evaluated additional findings characterizing pancreatic lesions by FDG-PET/MRI fusion image. METHODS: We analyzed retrospectively 119 patients: 96 cancers and 23 benign lesions. FDG-PET/MRI fusion images (PET/T1 WI or PET/T2WI) were made by dedicated software using 1.5 Tesla (T) MRI image and FDG-PET images. These images were interpreted by two well-trained radiologists without knowledge of clinical information and compared with FDG-PET/CT images. We compared the differential diagnostic capability between PET/CT and FDG-PET/MRI fusion image. In addition, we evaluated additional findings such as tumor structure and tumor invasion. RESULTS: FDG-PET/MRI fusion image significantly improved accuracy compared with that of PET/CT (96.6 vs. 86.6 %). As additional finding, dilatation of main pancreatic duct was noted in 65.9 % of solid types and in 22.6 % of cystic types, on PET/MRI-T2 fusion image. Similarly, encasement of adjacent vessels was noted in 43.1 % of solid types and in 6.5 % of cystic types. Particularly in cystic types, intra-tumor structures such as mural nodule (35.4 %) or intra-cystic septum (74.2 %) were detected additionally. Besides, PET/MRI-T2 fusion image could detect extra benign cystic lesions (9.1 % in solid type and 9.7 % in cystic type) that were not noted by PET/CT. CONCLUSIONS: In diagnosing pancreatic lesions, FDG-PET/MRI fusion image was useful in differentiating pancreatic cancer from benign lesions. Furthermore, it was helpful in evaluating relationship between lesions and surrounding tissues as well as in detecting extra benign cysts.

Pharmacokinetic alteration of (99m)Tc-MAG3 using serum protein binding displacement method.

INTRODUCTION: When a radiopharmaceutical is simultaneously administered with a medicine that has high affinity for the same plasma protein, the radiopharmaceutical is released at higher concentrations in blood, leading to enhanced transfer into target tissues. This is known as the serum protein binding displacement method. In this study, we investigated the pharmacokinetic alteration of technetium-99m-labeled mercaptoacetylglycylglycylglycine ((99m)Tc-MAG3) using the serum protein binding displacement method. METHODS: Rat and human serum protein binding rates of (99m)Tc-MAG3 were measured by ultrafiltration with or without displacers of human serum albumin (HSA) binding sites I and II (200µM and 400µM loading). Male Wistar rats were injected with (99m)Tc-MAG3 (740kBq/0.3mL saline) via the tail vein, and biodistribution was assessed at 2, 5, 10 and 15min. Dynamic whole-body images were obtained for (99m)Tc-MAG3 (11.1MBq/0.3mL saline)-injected rats, with or without HSA displacers. RESULTS: (99m)Tc-MAG3 strongly bound to HSA (87.37%±2.13%). Using HSA site I displacers, the free fraction of (99m)Tc-MAG3 increased significantly (1.20 to 1.47 times) when compared with controls. For biodistribution and imaging, rapid blood clearance was observed with bucolome (BCL) loading, which is an HSA site I displacer. With BCL loading, peak times for rat renograms were respectively shifted from 240s to 110s, and from 170s to 120s. CONCLUSIONS: We found that (99m)Tc-MAG3 bound to the HSA binding site I. It was confirmed that pharmacokinetic distribution of (99m)Tc-MAG3 is altered by presence of BCL, which leads to increases in the free fraction of (99m)Tc-MAG3, and BCL produced rapid blood clearance and fast peak times on rat renograms. The serum protein binding displacement method using (99m)Tc-MAG3 and BCL, a safe displacer for humans, may be applicable to clinical study and lead to better diagnostic images with shorter waiting times and lower radiation doses for patients.

Glucose metabolism in the primary auditory cortex of postlingually deaf patients: an FDG-PET study.

BACKGROUND/PURPOSE: Previous FDG-PET studies have indicated neuroplasticity in the adult auditory cortex in cases of postlingual deafness. In the mature brain, auditory deprivation decreased neuronal activity in primary auditory and auditory-related cortices. In order to reevaluate these issues, we used statistical analytic software, namely a three-dimensional stereotaxic region of interest template (3DSRT), in addition to statistical parametric mapping (SPM; Institute of Neurology, University College of London, UK). MATERIALS AND METHODS: (18)F-FDG brain PET scans were performed on 7 postlingually deaf patients and 10 healthy volunteers. Significant increases and decreases of regional cerebral glucose metabolism in the patient group were estimated by comparing their PET images with those of healthy volunteers using SPM analysis and 3DSRT. RESULTS: SPM revealed that the glucose metabolism of the deaf patients was lower in the right superior temporal gyrus, both middle temporal gyri, left inferior temporal gyrus, right inferior lobulus parietalis, right posterior cingulate gyrus, and left insular cortex than that of the control subjects. 3DSRT data also revealed significantly decreased glucose metabolism in both primary auditory cortices of the postlingually deaf patients. CONCLUSION: SPM and 3DSRT analyses indicated that glucose metabolism decreased in the primary auditory cortex of the postlingually deaf patients. The previous results of PET studies were confirmed, and our method involving 3DSRT has proved to be useful.

Role of the standardized uptake value of 18-fluorodeoxyglucose positron emission tomography-computed tomography in detecting the primary tumor and lymph node metastasis in colorectal cancers.

PURPOSE: To assess the role of positron emission tomography-computed tomography (PET-CT) and multidetector-row CT (MD-CT) in detecting the primary lesion and lymph node metastasis in patients with colorectal cancers. METHODS: A collective total of 80 lesions resected from 77 patients were examined pathologically. We analyzed the significance of the standardized uptake value (SUV) and its relationship with the clinicopathologic findings of primary lesions and lymph node metastasis. The detectability of primary lesions and lymph node metastases on PET-CT images was compared with that on MD-CT images. RESULTS: The detectability of primary lesions was better on PET-CT images than on MD-CT images (p = 0.0023). We observed no significant differences in the SUV with respect to staging, tumor grade, lymphatic or vessel invasion, and macroscopic type; however, primary tumor size analysis revealed that tumors larger than 3 cm had a higher SUV than those smaller than 3 cm. The sensitivity of PET-CT for detecting lymph node metastasis was lower than that of MD-CT, but the specificity of PET-CT was higher than that of MD-CT. CONCLUSIONS: The SUV of primary cancers tends to increase in proportion to tumor size. Although the value of PET-CT in detecting lymph node metastasis is limited, PET -positive lymph nodes can be considered metastatic.