Usefulness of both PET/CT with F18-FDG and whole-body diffusion-weighted imaging in cancer screening: a preliminary report.

OBJECTIVE: Positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose (F18-FDG) is useful for the detection of malignant lesions, including metastatic lesions, and this technique is widely used in cancer screening. However, this approach may occasionally yield false-positive and false-negative findings. At our PET center, to increase the accuracy of PET/CT, we use PET/CT and whole-body diffusion-weighted imaging (WB-DWI) together. This study aimed to assess the usefulness of this combination. METHODS: We examined 29 subjects with confirmed diagnosis. All of them had undergone PET/CT and WB-DWI on the same day. Twenty-seven of them also underwent ultrasonography, blood testing, and upper gastrointestinal series on the same day and two fecal occult blood tests on another day. WB-DWI was performed on a 1.5-T MRI unit with a b value of 0 and 800 or 1000 s/mm2. For all 29 cases, PET/CT and WB-DWI were classified to be positive or negative, and the diagnostic ability was calculated for each modality. RESULTS: Among the 29 subjects, 17 had malignant tumors and 12 had benign tumors or no abnormalities. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 65%, 25%, 55%, 33%, and 48%, respectively; while the corresponding values for WB-DWI were 59%, 100%, 100%, 63%, and 76%, respectively. By considering the result to be negative when PET/CT findings were positive but WB-DWI findings were negative, specificity increased from 25 to 100%, and accuracy increased from 48 to 76%. On the other hand, by considering the result to be positive when the findings of either PET/CT or WB-DWI were positive, sensitivity increased from 65 to 76%, and accuracy increased from 48 to 55%. CONCLUSIONS: Our results suggest that using both PET/CT and WB-DWI together can increase accuracy in cancer screening. However, this approach was not able to detect malignant lesions in some cases, indicating that there were limitations with imaging certain organs. Therefore, it is important to further understand the features of PET/CT and WB-DWI and use them appropriately for each organ. Additionally, given that the study sample was relatively small, further research is needed to validate these findings.

An iterative reconstruction using median root prior and anatomical prior from the segmented mu-map for count-limited transmission data in PET imaging.

OBJECTIVE: Recently, whole-body positron emission tomography (PET) examination has greatly developed. To reduce the overall examination time, the transmission scan has been increasingly shortened. Many noise-reduction processes have been developed for count-limited transmission data. Segmented attenuation correction (SAC) is one method by which the pixel values of transmission image are transformed into several groups. The median root prior-ordered subset convex (MRP-OSC) algorithm is another method that is applicable to control the noise level on the basis that the change of the pixel value is locally monotonous. This article presents an alternative approach on the basis of the Bayesian iterative reconstruction technique incorporating a median prior and an anatomical prior from the segmented mu-map for count-limited transmission data. METHODS: The proposed method is based on the Bayesian iterative reconstruction technique. The median prior and the anatomical prior are represented as two Gibbs distributions. The product of these distributions was used as a penalty function. RESULTS: In the thorax simulation study, the mean square error from the true transmission image of the presented method (5.74 x 10(-5)) was lower than MRP-OSC (6.72 x 10(-5)) and SAC (7.08 x 10(-5)). The results indicate that the noise of the image reconstructed from the proposed technique was decreased more than that of MRP-OSC without segmentation error such as that of an SAC image. In the thorax phantom study, the emission image that was corrected using the proposed technique displayed little noise and bias (27.42 +/- 0.96 kBq/ml, calculated from a region of interest drawn on the liver of the phantom); it was very similar to the true value (28.0 kBq/ml). CONCLUSIONS: The proposed method is effective for reducing propagation of noise from transmission data to emission data without loss of the quantitative accuracy of the PET image.

Auditory Related Resting State fMRI Functional Connectivity in Tinnitus Patients: Tinnitus Diagnosis Performance.

OBJECTIVE: The purpose of the present study was to investigate functional connectivity in tinnitus patients with and without hearing loss, and design the tinnitus diagnosis performance by resting state functional magnetic resonance imaging (rs-fMRI). SUBJECTS AND METHODS: Nineteen volunteers with normal hearing without tinnitus, 18 tinnitus patients with hearing loss, and 11 tinnitus patients without hearing loss were enrolled in this study. The subjects were evaluated with rs-fMRI, and region of interests (ROIs) based correlation analyses were performed using the CONN toolbox version 16 and SPM version 8. The correlation coefficients from individual level results were converted into beta values. RESULTS: With a beta threshold of more than 0.2, 91% of all possible connections between auditory-related ROIs (Heschl's gyrus, planum temporale, planum polare, operculum, insular cortex, superior temporal gyrus) in the control group remained intact, whereas 83 and 66% of such connections were present in the hearing loss and the normal-hearing tinnitus group. However, between non-auditory-related ROIs, the rates of intact connections at a beta threshold of more than 0.2 were 17% in the control group, and 16 and 15% in the tinnitus groups. When resting state fMRI positive is defined as less than 9% of all possible connections between auditory-related ROIs with a beta threshold of more than 0.7, the sensitivity and specificity of tinnitus diagnosis is 86 and 74%, respectively. CONCLUSIONS: The associations between auditory-related networks are weakened in tinnitus patients, even if they have normal hearing. It is possible that rs-fMRI can be a tool for objective examination of tinnitus, by focusing the auditory-related areas.

Cancer screening of healthy volunteers using whole-body 18F-FDG-PET scans: The Nishidai clinic study.

In order to evaluate the diagnostic performance of cancer screening using whole-body (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) scanning for asymptomatic subjects, we conducted a historical cohort study. The study group comprised 5807 individuals who underwent PET scanning from 2002 to 2003. Each subject had carried out a procedure with whole-body (18)F-FDG-PET scan with some other diagnostic tests. Out of 5807 participants, data from 4881 subjects were analysed. Among them, PET screening revealed abnormal FDG uptake in 562 subjects, and possible or probable malignancy in 324 subjects, and histological diagnosis of cancer in 36 subjects (16 thyroid, seven colon, four lung, five breast, two prostate, and two others) out of them. The overall cancer detection rate was 0.7%, and PET scanning had a sensitivity of 70.6% and a specificity of 94.0%. This result warrants further prospective cohort studies to evaluate the usefulness of PET cancer screening for cancer prevention.

Inter-observer variations in FDG-PET interpretation for cancer screening.

BACKGROUND: Diagnostic guidelines for the use of 2-(fluorine 18) fluoro-2 deoxy-D-glucose (FDG)-positron emission tomography (PET) in cancer screening have yet to be established. We assessed inter-observer variability in screening FDG-PET. METHODS: Subjects comprised 40 individuals who underwent FDG-PET and computed tomography (CT) for cancer screening. To assess various patterns of FDG uptakes, three subsets of the cases were selected: 'Cancer', 15 cases with cancer; 'Not malignant', 15 cases with suspected cancer by FDG-PET who were confirmed as cancer-free; and 'Normal', 10 cases without remarkable FDG uptake who were confirmed as cancer-free. A total of 68 lesions made up of malignancy (n = 18), benign (n = 21), and physiological FDG uptake (n = 29) were interpreted by six physicians. Each observer reviewed each case three times. Step 1 involved interpretation of PET images alone, Step 2 involved side-by-side reading of PET and CT images, and Step 3 involved re-evaluation of findings with the results of other screening tests. We assessed inter-observer agreement for each step. RESULTS: Inter-observer agreement for all lesions at each step was moderate, compared to fair agreement for 'Normal' subjects. Inter-observer agreement of 'Cancer' and 'Not malignant' subjects in Step 1 were better than those in Step 2 and 3; however, the differences were not statistically significant. CONCLUSION: The interpretation of FDG-PET is adequately reproducible, while that of 'Normal' subjects is less reproducible. Improvement of inter-observer variability in assessing physiological FDG uptakes requires universal reporting criteria in FDG-PET. Correlative interpretation of PET, CT and other information may require standardization in subjects with suspected cancer by FDG-PET.

Performance profile of FDG-PET and PET/CT for cancer screening on the basis of a Japanese Nationwide Survey.

OBJECTIVE: The aim of this study is to survey the situation of (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening in Japan and to describe its performance profile. METHODS: "FDG-PET for cancer screening" was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. We sent questionnaires regarding FDG-PET cancer screening to 99 facilities in which FDG-PET tests were performed during the fiscal year 2005. Replies were obtained from 68 of the 99 facilities, of which 46 facilities performed FDG-PET cancer screening. The total number of subjects who underwent FDG-PET cancer screening was 50 558. From 38 of 46 facilities, reliable results of thorough examinations were obtained for the subjects who were positive by FDG-PET and/or one or more of the combined screening tests was performed and were referred for further evaluation. The total number of subjects in these 38 facilities amounted to 43 996. RESULTS: A total of 50,558 healthy subjects underwent FDG-PET (including PET/CT) scanning with or without other tests for cancer screening in 46 PET centers during the fiscal year of 2005 in Japan. Thorough examination was indicated for 9.8% of the cases as a result of positive findings suggesting possible cancer. On analyzing 43 996 cases from 38 PET centers from which detailed information was obtained, 500 cases of cancers (1.14%) were found, of which 0.90% were PET positive and 0.24% were PET negative, resulting in the relative sensitivity of PET being 79.0%. Cancers of the thyroid, colon/rectum, lung, and breast were most frequently found (107, 102, 79, and 35 cases, respectively) with high PET sensitivity (88%, 90%, 80%, and 92%). PET showed an overall positive predictive value of 29.0%. PET/CT had a better detection rate, sensitivity, and positive predictive value than dedicated PET (P < 0.01). CONCLUSIONS: We were able to clarify the performance profile of "FDG-PET for cancer screening" on the basis of a Japanese nationwide survey. The number of facilities possessing PET is increasing steadily, highlighting the necessity of evaluating the usefulness of "FDG-PET cancer screening" as soon as possible by undertaking long-term investigations of large series of subjects.

[Imaging of cancer activity and range of tumor involvement--applying to breast cancer].

In recent years, PET using mainly fluorine-18 fluorodeoxyglucose (FDG) has played a very large role in the management of breast cancer. Systemic, functional images can be obtained by whole body PET and can provide information that is not obtained by anatomical imaging modalities such as conventional X-ray computed tomography, X-ray mammography, or ultrasonography. The utility of FDG-PET for breast cancer patients has been established in every phase of the management of breast cancer, such as the differential diagnosis of breast cancer primary lesion, cancer staging, and posttreatment monitoring. For whole body FDG-PET that can assess the spread of systemic disease in a single examination, postoperative monitoring is one of the most useful applications in particular. In addition, the usefulness of PET for prediction of prognosis and assessment of treatment response has been reported along with the medical economical effect of FDG-PET for breast cancer patients. Moreover, it is expected that a new tracer other than FDG, such as fluorine-18 ion and [18F]-fluoro-17beta; estradiol (FES), and the new instruments such as PET-CT and positron emission mammography (PEM) can further contribute to the management of breast cancer. In this report, we will outline the benefits, limitations, and future prospects of PET for breast cancer.

[Performance profile of FDG-PET and PET/CT for cancer screening based on a Japanese nationwide survey].

A total of 50,558 healthy subjects underwent an FDG-PET (including PET/CT) scan with or without combination of other tests for cancer screening in 46 PET centers during fiscal year of 2005 in Japan. Thorough examination was indicated for 9.8% of the cases due to positive findings suggesting possible cancer. On analyzing 43,996 cases from 38 PET centers, where detailed information was obtained, 500 cases of cancers (1.14%) were found, of which 0.90% was PET positive and 0.24% was PET negative, resulting in the relative sensitivity of PET being 79.0%. Cancers of thyroid, colon/rectum, lung and breast were most frequently found (107, 102, 79, 35 cases, respectively) with high PET sensitivity (88%, 90%, 80%, 92%). PET showed an overall positive predictive value of 29.0%. PET/CT had better detection rate, sensitivity, and positive predictive value than dedicated PET (p<0.01).

Giant cell arteritis with polymyalgia rheumatica on FDG-PET/CT.

If there is no pain in the temporal artery, the diagnosis of giant cell arteritis (GCA) may be delayed and blindness may occur. Therefore, FDG-PET/CT is important as a modality for diagnosis of GCA. When GCA is suspected and F-18 FDG-PET/CT is performed, it is worthwhile to pay attention to shoulder and hip joints as polymyalgia rheumatica commonly presents with GCA.

FDG-PET imaging for lymph node staging and pathologic tumor response after neoadjuvant treatment of non-small cell lung cancer.

PURPOSE: A number of studies have demonstrated that 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is effective for staging of lung cancer. However, the efficacy of FDG-PET for staging lung cancer after neoadjuvant treatment is still controversial. This study compared FDG-PET and computed tomography (CT) for lung cancer staging, and evaluated the ability of the two methods to predict the pathologic response of the primary tumor to neoadjuvant treatment. PATIENTS AND METHODS: Twenty-two patients who underwent neoadjuvant treatment followed by surgery were investigated. Eighteen patients received chemoradiotherapy and four patients received chemotherapy only. One hundred and three lymph node stations in the 22 patients were evaluated by FDG-PET and CT. The pathologic responses of the tumors were compared by FDG-uptake and tumor size on CT for the 15 patients who underwent FDG-PET and CT both before and after neoadjuvant treatment. RESULTS: There was no significant difference in the ability of FDG-PET or CT to predict residual viable tumor. Although positive predictive value by FDG-PET (0.29) was lower than that by CT (0.64) (p=0.04) in the mediastinal lymph nodes, there were no statistically significant differences in the other results of lymph nodes by FDG-PET and CT. Both decrease in FDG-uptake and decrease in tumor size by CT after neoadjuvant treatment correlated significantly with pathologic response in the 15 patients (p=0.003 and 0.009, respectively). CONCLUSION: FDG-PET did not appear to offer any advantages over CT for lymph node staging or for predicting the pathologic response after neoadjuvant treatment of non-small cell lung cancer.

[Usefulness of 18F-FDG PET in the diagnosis for breast cancer patients].

Whole-body 18F-FDG PET is useful for qualitative diagnosis of breast mass and for preoperative staging, evaluation of therapeutic effect, prediction of prognosis, and detection of recurrence or metastasis in case of breast cancer. In addition, 18F-FDG PET is being actively used for cancer screening in Japan. 18F-FDG PET has almost equal or higher. capacity in detecting recurrence or metastasis of breast cancer as compared with conventional morphological study such as CT or MRI. However it should be noticed of the existence of false-negative and false-positive findings in some cases. In this paper we refer to the advantages and disadvantages of 18F-FDG PET in managing patients with breast cancer.

Auditory resting-state functional connectivity in tinnitus and modulation with transcranial direct current stimulation.

CONCLUSIONS: The functional connectivity (FC) between the right and left auditory cortex is weak in tinnitus patients. Transcranial direct current stimulation (tDCS) over the auditory cortex has potential as a tool to modulate auditory-based FC. OBJECTIVE: This study investigated the effects of applying tDCS in tinnitus patients, and searched for modulation of brain networks in resting-state functional magnetic resonance imaging (rs-fMRI) through an analysis of FC with the stimulated brain region. SUBJECTS AND METHODS: Nine male patients with chronic tinnitus and 10 male volunteers with normal hearing were enrolled. The subjects were evaluated with rs-fMRI immediately before and after tDCS. The tinnitus patients filled out the self-evaluation questionnaires designed to measure tinnitus conditions before tDCS treatment and 1 week afterwards. RESULTS: The FC between the right and left auditory cortex was significantly weaker in tinnitus patients than in controls. After tDCS treatment, in the tinnitus group, the primary auditory cortex showed a reduction in the amount of statistically significant connectivity with the somatosensory area and motor area, but maintained strong significant connectivity (p < 0.005) with the auditory area and insular cortex. In contrast, in the control group, there remained strong significant connectivity between the primary auditory cortex and the somatosensory area, motor area, insular cortex, and auditory area.

The size of metastatic foci and lymph nodes yielding false-negative and false-positive lymph node staging with positron emission tomography in patients with lung cancer.

BACKGROUND: We examined the sizes of lymph nodes and metastatic foci within the lymph nodes that affect false-positive and false-negative lymph node staging by positron emission tomography in lung cancer. METHODS: Preoperative positron emission tomography and computed tomography scans were performed for 564 lymph node stations in 80 patients with peripheral-type lung cancer. The sizes of both the lymph nodes and the metastatic foci within the lymph nodes were measured, and these measurements were compared with those obtained with positron emission tomography scanning. To establish general sizes of metastatic foci within the lymph nodes, 277 metastatic lymph nodes in operative specimens previously resected from another 111 patients with lung cancer were examined as a control. RESULTS: The sensitivity was significantly higher for positron emission tomography than for computed tomographic scanning (P =.026). The sizes of metastatic foci within lymph nodes that showed false-negative (n = 8) and true-positive (n = 28) with positron emission tomography ranged from 0.5 to 9 mm (3 +/- 1 mm) and from 4 to 18 mm (10 +/- 3 mm), respectively (P <.001). None of the metastatic foci smaller than 4 mm could be detected with positron emission tomography scanning. The review of the 277 previously resected metastatic lymph nodes showed that 89 (32%) had metastatic foci smaller than 4 mm. The sizes of true-positive (n = 28) and false-positive (n = 10) lymph nodes ranged from 6 to 15 mm (10 +/- 2 mm) and from 9 to 16 mm (12 +/- 2 mm), respectively (P <.01). None of the false-positive lymph nodes was smaller than 9 mm. CONCLUSIONS: Although positron emission tomography was superior to computed tomography scanning in lymph node staging in lung cancer, positron emission tomography was unable to distinguish metastatic foci smaller than 4 mm, which were not unusual sizes for lymph node metastases in lung cancer. Positive lymph nodes with positron emission tomography smaller than 9 mm are likely to be true-positive rather than false-positive.

Fluorine 18-tagged fluorodeoxyglucose positron emission tomographic scanning to predict lymph node metastasis, invasiveness, or both, in clinical T1 N0 M0 lung adenocarcinoma.

OBJECTIVE: We sought to predict lymph node metastasis and tumor invasiveness in clinical T1 N0 M0 lung adenocarcinomas, and we measured fluorodeoxyglucose uptake on positron emission tomography. METHODS: Fluorodeoxyglucose positron emission tomography was performed on 44 patients with adenocarcinomas of 1 to 3 cm in size clinically staged as T1 N0 M0 before major lung resection with lymph node dissection. Fluorodeoxyglucose uptake was evaluated by using the contrast ratio between the tumor and contralateral healthy lung tissue. Lymphatic and vascular invasion within tumors, pleural involvement, and grade of histologic differentiation were examined. RESULTS: The pathologic tumor stage was T1 N0 M0 in 36 patients, and a more advanced stage was found in 8 patients. Although all 22 adenocarcinomas with a contrast ratio of less than 0.5 in fluorodeoxyglucose uptake were pathologic T1 N0 M0 tumors, 8 (36%) of 22 with a contrast ratio of 0.5 or greater were of a more advanced stage than T1 N0 M0, with the difference being significant (P =.002). Adenocarcinomas with a contrast ratio of less than 0.5 showed less lymphatic and vascular invasion and less pleural involvement than those with a contrast ratio of 0.5 or greater (P =.006, P =.004, and P =.02, respectively). The grade of histologic differentiation was well differentiated in 19 of 22 adenocarcinomas with a contrast ratio of less than 0.5 (86%), which was a greater frequency than the 4 (18%) of 22 adenocarcinomas with a contrast ratio of 0.5 or greater (P <.001). CONCLUSION: Clinical T1 N0 M0 lung adenocarcinomas with a contrast ratio of less than 0.5 usually did not have lymph node metastasis, had less tumor involvement of vessels or pleura, and were more frequently well differentiated than those with a contrast ratio of 0.5 or greater. Limited lung resection could be indicated, lymph node dissection or mediastinoscopy could be reduced, or both in this type of adenocarcinoma.

Evaluation of F-18 fluorodeoxyglucose (FDG) PET scanning for pulmonary nodules less than 3 cm in diameter, with special reference to the CT images.

BACKGROUND: While pulmonary nodules can be substantially divided into solid and ground-glass opacity (GGO) ones on CT image, they have different biological natures which could cause false positive or false negative to diagnose malignancy on positron emission tomography with fluorodeoxyglucose (FDG-PET). To determine the effectiveness of PET for small pulmonary nodules, the nodules were classified into solid and GGO ones, of which results were compared with the data of PET scans. The lower limit size of nodules for PET imaging was also evaluated. METHODS: Prospective FDG-PET scans were undertaken for 136 non-calcified nodules less than 3 cm in diameter. CT density histograms were made for each nodule to classify into solid and GGO ones. RESULTS: Eighty-one nodules were malignant and 55 were benign. All of the 20 nodules less than 1 cm in diameter (n = 8 in malignant, n = 12 in benign), were negative on PET regardless of the histology. In the 116 nodules 1-3 cm in diameter (n = 73 in malignant, n = 43 in benign), there were 15 false negative and 15 false positive nodules, with a sensitivity of 79% and specificity of 65%. CT density histograms showed 101 solid nodules (n = 63 in malignant, n = 38 in benign) and 15 GGO nodules ( n = 10 in malignant, n = 5 in benign). All of the 10 malignant nodules with GGO images were histologically well-differentiated adenocarcinoma and 9 of them (90%) were false negative on PET. Four of the 5 (80%) benign nodules with GGO images were focal pneumonia with well-preserved air spaces, causing false positive on PET. Sensitivity and specificity for nodules with GGO images were 10 and 20%, respectively, which were significantly lower than 90 and 71% for nodules with solid images (P < 0.001). CONCLUSION: Pulmonary nodules which are less than 1cm in size or show GGO images on CT cannot be evaluated accurately by PET.

Synthesis and evaluation of (11)C-labeled (S)-N-[[1-(2-phenylethyl) pyrrolidin-2-yl]methyl]-3-methylthiobenzamide as a PET 5-HT(1A) receptor ligand.

We prepared 5-HT(1A) receptor ligands (S)-N-[[1-(2-phenylethyl)pyrrolidin-2-yl]methyl]-3-[11C]methylthiobenzamide ([11C](S)-PPMMB) (Ki = 4.3 nM) and the less active [(11)C](R)-PPMMB (Ki = 160 nM) by reduction of the disulfide dimer and subsequent [(11)C]methylation of demethyl (S)- and (R)-PPMMB, respectively. Both radioligands showed similar brain distribution in mice with relatively higher affinity for the hippocampus being rich in 5-HT(1A) receptors than for other brain regions. Uptake of [(11)C](S)-PPMMB was not reduced by carrier-loading nor by pretreatment with 5-HT(1A) receptor ligands. [(11)C](S)-PPMMB is therefore not a suitable radioligand for mapping 5-HT(1A) receptors using positron emission tomography.

[False negative cases of F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging in small lung cancer less than 3 cm in size].

A considerable number of false negative cases in FDG-PET were seen in small-cell lung cancer, despite the usefulness of this imaging modality. We investigated the correlation between FDG-PET results and the clinicopathological findings in small lung cancers less than 3 cm in size. Fifty-one consecutive cases of surgically resected small lung cancers scanned preoperatively by FDG-PET was assessed. The medical records of each case were reviewed for the maximum tumor size in the CT findings, histology, grade of differentiation, lymphatic and vascular invasion, pleural invasion, lymph node stage, serum level of carcinoembryonic antigen (CEA), and CT findings. All of the 5 cases (4 adenocarcinomas, 1 small-cell carcinoma) less than 1 cm in size were false negatives. In the 46 cases 1-3 cm in size (34 adenocarcinomas, 9 squamous sell carcinomas, 2 large sell carcinomas, 1 small cell carcinoma), false negative results were seen in 8 of 15 cases of well-differentiated adenocarcinoma (53%). In the 8 false negative cases, 1 (13%) lymphatic vessel invasion (ly), 0 (0%) vascular vessel invasion (v), 0 (0%) pleural invasion (p), 0 (0%) lymph node metastasis, 0 (0%) high serum level of CEA, and 5 (63%) cases showing ground-glass opacity on CT were observed. There were significant differences in the factors ly, v, CEA, and CT findings between the 8 false-negative cases and the 26 true positive cases with adenocarcinoma (p < 0.01-0.05). Lung cancers < 1 cm in size cannot be detected in FDG-PET. Adenocarcinomas of the lung 1-3 cm in size with false negatives in FDG-PET showed significantly less invasiveness than the true positives.

Detection of lung cancer by FDG-PET cancer screening program: a nationwide Japanese survey.

AIM: The aim of this study was to analyze the lung cancer detection rate in asymptomatic individuals by the Fluorine-18 fluorodeoxyglucose-positron emission tomography FDG-PET cancer screening program in Japan. MATERIALS AND METHODS: A total of 153,775 asymptomatic individuals underwent the FDG-PET cancer screening program; the 854 cases with findings that indicated suspected lung cancer by any detection method were analyzed. RESULTS: Among the 854 cases, 319 were verified as lung cancer. The relative sensitivity and positive predictive value (PPV) of FDG-PET were 86.5% and 38.9% for lung cancer, respectively. The sensitivity of PET/computed tomography (CT) scanner was higher than that of dedicated PET (100.0% vs. 63.2%), indicating that CT imaging was effective for lung cancer screening. The majority of lung carcinomas detected by FDG-PET screening were UICC stage IA or IB, but detection of smaller or less invasive carcinomas was limited. CONCLUSION: The FDG-PET screening program in Japan detected lung cancer at an early stage.

Long fasting is effective in inhibiting physiological myocardial 18F-FDG uptake and for evaluating active lesions of cardiac sarcoidosis.

BACKGROUND: F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a promising modality for detecting active lesions of cardiac sarcoidosis (CS). However, determining whether 18F-FDG uptake in the myocardium is physiological is challenging due to metabolic shift in myocardial cells. Although methods for inhibiting physiological myocardial 18F-FDG uptake have been proposed, no standard methods exist. This study therefore aimed to compare the effect of an 18-h fast (long fasting (LF)) with heparin loading plus a 12-h fast (HEP) before 18F-FDG PET scan. METHODS: We analyzed the effects of LF and HEP on the inhibition of physiological myocardial 18F-FDG uptake in healthy subjects (18 in HEP and 19 in LF) and in patients with known or suspected CS (96 in HEP and 69 in LF). In CS, the lower uptake of 18F-FDG in the myocardium was evaluated. A visual four-point scale was used to assess myocardial 18F-FDG uptake in comparison with hepatic uptake (1 lower, 2 similar, 3 somewhat higher, 4 noticeably higher). RESULTS: Myocardial 18F-FDG uptake was 1.68 ± 1.06 in LF and 3.17 ± 1.16 in HEP in healthy subjects (p < 0.0001), whereas it was 1.48 ± 0.99 in LF and 2.48 ± 1.33 in HEP in CS patients (p < 0.0001). Logistic regression and regression trees revealed the LF was the most effective in inhibiting myocardial 18F-FDG uptake. In addition, serum free fatty acid levels on intravenous 18F-FDG injection were a possible biomarker. CONCLUSIONS: LF is effective in inhibiting myocardial 18F-FDG uptake, and consequently, it could be useful for evaluating active lesions of CS in 18F-FDG PET images.