Keiichi Ishihara

Significant suppression of myocardial 18F-fluorodeoxyglucose uptake using 24-h carbohydrate restriction and a low-carbohydrate, high-fat diet

OBJECTIVES (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is a useful tool for evaluating inflammation. Because, myocardial-FDG uptake occurs with diverse physiology, it should be suppressed during evaluation of myocardial inflammation by FDG-PET/CT. Diets inducing fat-based metabolism, such as a low-carbohydrate, high-fat diet (LCHF), are used in uptake-suppression protocols. However, a complete suppression of myocardial-FDG uptake has not been established. Hence, we assessed the efficacy of 24-h carbohydrate restriction along with an LCHF diet compared to that of the conventional protocol in suppressing myocardial-FDG uptake and also compared fat and glucose metabolism between these protocols. METHODS Fourteen healthy volunteers agreed to undergo >24-h carbohydrate restriction (glucose, <10g) and drank an LCHF beverage an hour before FDG administration. A scan performed under conventional fasting protocol served as the control. The maximal standardized uptake values (SUVmax) of the left ventricular (LV) myocardium, and left atrium lumen (blood pool), liver, and lung fields as background, were measured. Blood sugar, free fatty acids (FFAs), insulin, and triglyceride concentrations were measured just before FDG injection and compared between the 2 protocols. RESULTS Global LV myocardial uptake was significantly lower with the diet-preparation protocol (SUVmax 1.31 [1.15-1.49] vs. 2.98 [1.76-6.43], p=0.001). Target-to-background ratios [myocardium-to-blood ratio (MBR), myocardium-to-lung ratio (MLR), and myocardium-to-liver ratio (MLvR)] were also significantly lower with the diet-preparation protocol [MBR: 0.75 (0.68-0.84) vs. 1.63 (0.98-4.09), p<0.001; MLR: 1.87 (1.53-2.47) vs. 4.54 (2.53-12.78), p=0.004; MLvR: 0.48 (0.44-0.56) vs. 1.11 (0.63-2.32), p=0.002]. Only insulin levels were significantly different between the subjects in each protocol group (11.3 [6.2-15.1] vs. 3.9 [2.9-6.2]). CONCLUSION Carbohydrate restriction together with an LCHF supplement administered 1h before FDG significantly suppressed myocardial-FDG uptake. FFAs and insulin might not directly affect myocardial-FDG uptake.

FDG-PET/CT in the diagnosis of recurrent breast cancer

Background An advantage of PET/CT has been demonstrated for diagnosis of several tumor entities. In patients with breast cancer, early diagnosis and accurate restaging of recurrence after surgery is important for selection of the most appropriate therapeutic strategy. Purpose To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG), for follow-up of patients with suspected recurrent breast cancer. Material and Methods Forty-seven patients with suspected recurrent breast cancer underwent PET/CT. The PET and PET/CT images were interpreted without knowledge of the results of other diagnostic modalities, and compared with each other with reference to the final diagnosis. Results Twenty-five (53%) patients suffered tumor recurrence. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 96%, 91%, 92%, 95%, and 94%, respectively. In comparison with PET, PET/CT had a higher sensitivity and accuracy (96% vs. 80% and 94% vs. 81%, respectively). The difference in diagnostic accuracy between PET/CT and PET was significant (P < 0.05). Conclusion The present findings indicate that PET/CT is an accurate, sensitive and reliable modality for screening and detection of breast cancer recurrence. PET/CT appears to be an effective surveillance tool, as it is able to cover the whole body in a single procedure and shows good performance.

Comparison of imaging biomarkers for Alzheimer's disease: amyloid imaging with [18F]florbetapir positron emission tomography and magnetic resonance imaging voxel-based analysis for entorhinal cortex atrophy.

We compared amyloid positron emission tomography (PET) and magnetic resonance imaging (MRI) in subjects clinically diagnosed with Alzheimers disease (AD), mild cognitive impairment (MCI), and older healthy controls (OHC) in order to test how these imaging biomarkers represent cognitive decline in AD.

Striatal and extrastriatal dopamine D2 receptor occupancy by a novel antipsychotic, blonanserin: a PET study with [11C]raclopride and [11C]FLB 457 in schizophrenia.

Abstract Blonanserin is a novel antipsychotic with high affinities for dopamine D2 and 5-HT2A receptors, and it was recently approved for the treatment of schizophrenia in Japan and Korea. Although double-blind clinical trials have demonstrated that blonanserin has equal efficacy to risperidone, and with a better profile especially with respect to prolactin elevation, its profile of in vivo receptor binding has not been investigated in patients with schizophrenia. Using positron emission tomography (PET), we measured striatal and extrastriatal dopamine D2 receptor occupancy by blonanserin in 15 patients with schizophrenia treated with fixed doses of blonanserin (ie, 8, 16, and 24 mg/d) for at least 4 weeks before PET scans, and in 15 healthy volunteers. Two PET scans, 1 with [11C]raclopride for the striatum and 1 with [11C]FLB 457 for the temporal cortex and pituitary, were performed on the same day. Striatal dopamine D2 receptor occupancy by blonanserin was 60.8% (3.0%) [mean (SD)] at 8 mg, 73.4% (4.9%) at 16 mg, and 79.7% (2.3%) at 24 mg. The brain/plasma concentration ratio calculated from D2 receptor occupancy in the temporal cortex and pituitary was 3.38, indicating good blood-brain barrier permeability. This was the first study to show clinical daily dose amounts of blonanserin occupying dopamine D2 receptors in patients with schizophrenia. The clinical implications obtained in this study were the optimal therapeutic dose range of 12.9 to 22.1 mg/d of blonanserin required for 70% to 80% dopamine D2 receptor occupancy in the striatum, and the good blood-brain barrier permeability that suggested a relatively lower risk of hyperprolactinemia.

Amyloid imaging with [(18)F]florbetapir in geriatric depression: early-onset versus late-onset.

We examined patients with mild cognitive impairment (MCI) with a history of geriatric depression (GD) and healthy controls (HC) to evaluate the effect of beta‐amyloid (Aβ) pathology on the pathology of GD by using [18F]florbetapir PET.

The reproducibility of time-of-flight PET and conventional PET for the quantification of myocardial blood flow and coronary flow reserve with 13 N-ammonia

BackgroundThis study aimed to validate the reproducibility of quantitative analysis using time-of-flight (TOF) and conventional PET with 13N-ammonia (13N-NH3).Methods and ResultsPhantom images were reconstructed with and without TOF, and recovery coefficients (RCs) and the percent contrast of each sphere over the percent background variability were assessed. In the clinical study, 21 subjects underwent dynamic 13N-NH3 PET scanning under stress and rest conditions. The dynamic acquisition images and intra- and inter-observer reproducibility of myocardial blood flow (MBF) and coronary flow reserve (CFR) were compared between reconstructions (with and without TOF). In the phantom study, RCs and the percent contrast of each sphere over the percent background variability was improved with TOF. In the clinical study, the noise of blood pool and myocardial images with TOF was less than that without TOF. Territorial and global intra- and inter-observer reproducibility of MBF and CFR values was excellent. Although segmental intra- and inter-observer reproducibility was excellent, there were larger variations in apex and the segment near the right ventricle (RV) without TOF. These variations became inconspicuous with TOF.ConclusionVisual image quality, RCs, and percent contrast over percent background variability with TOF were better than that without TOF. Excellent correlations and good agreements in quantitative values were observed. TOF improved the variation of segmental values.

Usefulness of 201TlCl/123I-BMIPP dual-myocardial SPECT for patients with non-ST segment elevation myocardial infarction

ObjectiveEarlier studies suggested that elevated cardiac troponin T (cTnT) might be useful for detecting less severe types of myocardial injury (i.e., non-ST segment elevation myocardial infarction). The objective of this study is to elucidate the usefulness of 201thallous chloride (201TlCl) and 123I-betamethyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) dual-single-photon emission computed tomography (SPECT) imaging for patients with myocardial infarction (MI) without ST segment elevation.MethodsConsecutive 86 patients (56 men and 30 women; mean age 66 ± 12 years) clinically diagnosed with acute myocardial infarction (AMI) were divided into two groups according to serum creatine kinase MB (CK-MB) and cTnT levels. Group A consisted of 53 patients with increased serum CK-MB and cTnT levels, and Group B, 33 patients with increased serum cTnT without increased serum CK-MB. All patients underwent 201TlCl and 123I-BMIPP dual-SPECT about 8 days following the onset. The left ventricular myocardium was divided into 20 segments on each SPECT image, and tracer accumulation in those segments was scored on a five-point scoring system. The total defect scores (TDS) were calculated by summing the scores for all 20 segments, and compared between groups A and B. Group B patients were subdivided into two groups according to the TDS on 123I-BMIPP images as groups BS (severe; TDS ≥ 8) and BM (mild; TDS ≤ 7), and we compared the prognosis over a period of 2 years from the onset between the three groups.ResultsThe TDS of group A derived from 201TlCl and 123I-BMIPP images was significantly higher than those of group B (14.5 ± 10.8 vs. 1.5 ± 2.4 and 20.8 ± 13.3 vs. 9.1 ± 6.2, respectively; P < 0.0001). The sensitivities of 201TlCl and 123I-BMIPP images were 94.3% (50/53) and 96.2% (51/53) to detect the culprit coronary lesions in group A (no significant difference). In contrast, the sensitivity of 123I-BMIPP images (72.7%, 24/33) was higher than that of 201TlCl images (27.3%, 9/33) in group B (P < 0.05). At 2 years of follow-up, the incidence of hard cardiac events in groups A, BS, and BM was 24.5%, 27.8%, and 6.7%, respectively. The rate of group BS, as well as that of group A, was significantly higher than that of group BM (P < 0.05).ConclusionsOf those with a clinical diagnosis of AMI accompanied by increased cTnT, the CK-MB negative patients accounted for 38% (33/86) of all patients as having non-ST segment elevation myocardial infarction such as NTMI. For such patients, 123I-BMIPP imaging is useful not only for the detection of the culprit lesions but also for the prediction of the prognosis.

Normal model construction for statistical image analysis of torso FDG-PET images based on anatomical standardization by CT images from FDG-PET/CT devices

PurposeA better understanding of the standardized uptake value (SUV) ranges of fludeoxyglucose positron emission tomography (FDG-PET) is crucial for radiologists. We have developed a statistical image analysis method for FDG-PET imaging of the torso, based on comparisons with normal data. The purpose of this study was to verify the accuracy of the normal model and usefulness of the statistical image analysis method by using typical cancer cases in the liver, lungs, and abdomen.MethodsOur study and the data collection (49 normal and 34 abnormal cases, in terms of PET/CT findings) were approved by the institutional review board. Our scheme consisted of the following steps: (1) normal model construction, (2) anatomical standardization of patient images, and (3) Z-score calculation to show the results of the statistical image analysis. To validate the Z-score index, we sampled 3603 and 1270 voxels in normal organs and abnormal regions, respectively, from the liver, lungs, and the abdomen. We then obtained the SUV and Z-score for each region. A receiver operating characteristics (ROC) analysis-based method was performed to evaluate the discrimination performances of the SUV and Z-score.ResultsThe discrimination performances of the SUV and Z-score for the objective regions of interest (ROIs) were evaluated by the areas under the ROC curves (AUCs). As a result of the ROC analysis and statistical tests, all AUCs were found to be larger than 0.98. When the ROIs in the objective regions were combined, the mean AUCs of the Z-score and SUV were 0.99 and 0.98, respectively, the difference being statistically significant (

Evaluation of primary prostate cancer using 11C-methionine-PET/CT and 18F-FDG-PET/CT.

p < 0.001