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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. 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. 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%. 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.

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).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.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.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.

The aim of this study was to evaluate the interpretations of incidental colonic 18F-FDG uptake made by 10 experienced readers and to more clearly identify the pattern of suspicious colonic FDG uptake. The potential contributions of delayed FDG-PET scanning and of immune fecal occult blood testing (FOBT) in making a diagnosis were also analyzed.Visual interpretations by 10 readers were made for 147 FDG uptake sites from 126 PET scans (cancer, 38 sites; adenoma, 43 sites; and no abnormality, 66 sites) with colonic FDG uptake. Assessments for the early FDG-PET images were (1) FDG uptake pattern, (2) FDG uptake degree, and (3) likelihood of malignancy. For the delayed images, the assessments were (1) change in the FDG uptake position, (2) change in FDG uptake degree, and (3) likelihood of malignancy. The results of FOBT were analyzed independently of the visual interpretations.Interobserver agreement (κ) was 0.501 for assessing FDG uptake patterns, while agreement on assessing changes in uptake degree and changes in uptake position between early and delayed imaging were low (κ = 0.213-0.229). Logistic regression analysis indicated that 'FDG uptake patterns' and 'FDG uptake degree' were significantly related to decide on the suspicion of malignancy (p0.001) and the final result (p0.001). "Small localized" and "large irregular localized" types had a high probability of a lesion regardless of either (1) FDG uptake degree or (2) variation in the uptake between the early and the delayed image. The delayed image decreased false-positive cases for some FDG uptake patterns, but it had little impact on distinguishing clearly between "cancer or adenoma" and "normal". The addition of FOBT had little impact on the diagnosis.There was highest agreement among readers with respect to the recognition of specified colonic FDG uptake patterns, and this pattern recognition had the most influence on the diagnosis. "Small localized" and "large irregular localized" types had a high probability of a lesion. The addition of delayed imaging and of FOBT results to the early imaging did not have much impact on the diagnosis.

Objective The aim of this study was to survey the 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening program conducted in Japan. Methods The “FDG-PET cancer screening program” included both FDG-PET and positron emission tomography with computed tomography (PET/CT) with or without other combined screening tests that were performed for cancer screening in asymptomatic subjects. A total of 155,456 subjects who underwent the FDG-PET cancer screening program during 2006–2009 were analyzed. Results Of the 155,456 subjects, positive findings suggesting possible cancer were noted in 16,955 (10.9 %). The number of cases with detected cancer was 1,912 (1.23 % of the total screened cases, annual range 1.14–1.30 %). Of the 1,912 cases of detected cancer, positive findings on FDG-PET were present in 1,491 cases (0.96 % of the total number of screened cases). According to the results of further examinations, the true positive rate for subjects with suggested possible cancer (positive predictive value) was 32.3 % with FDG-PET. Cancers of the colon/rectum, thyroid, lung, and breast were most frequently found (396, 353, 319, and 163 cases, respectively) with high PET sensitivity (85.9, 90.7, 86.8, 84.0 %, respectively). Prostate cancer and gastric cancer (165 and 124 cases, respectively) had low PET sensitivity (37.0 and 37.9 %, respectively). The Union for International Cancer Control (UICC) clinical stage of cancer found with the FDG-PET cancer screening program was mainly Stage I. Conclusions The FDG-PET screening program in Japan has detected a variety of cancers at an early stage. However, several cancers were found in repeated FDG-PET cancer screening program, indicating the limitation of a one-time FDG-PET cancer screening program. The value of the FDG-PET cancer screening program is left to the judgment of individuals with regard to its potentials and limitations.

Key Clinical Message 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.

PET cancer screening is performed widely in Japan as opportunistic screening, but no study has focused on the correlation with various cancer risk factors and the seeking bias of examinees and cancer detection rate. Analyzing our large series of PET cancer screening data, correlations with cancer detection rates according to general cancer risk factors and PET detection survey were reviewed, and the selection bias of the medical examinees was determined. 19189 examinees who underwent PET cancer screening were enrolled. Using logistic-regression analysis, we analyzed correlations between smoking history/drinking history/cancer family history and detection rates of thyroid cancer/breast cancer/colorectal cancer/lung cancer, which are the main malignancies detected in PET cancer screening. In addition, we evaluated seeking bias of examinees, analyzing correlations between the presence of cancer risk factors and prior screening checkups at other institutions to our PET cancer screening using a matched case–control study. Cancer detection rates by FDG-PET were 1.17% (224/19189), being much higher than those of standard cancer mass screenings. In males, statistically significant correlations were seen between lung cancer and smoking, and between prostate cancer and a family history of prostate cancer, but not between the detection rates of three other types of cancer (thyroid cancer/lung cancer/colorectal cancer) and other cancer risk factors. In females, detection rates of four types of cancer (thyroid cancer/lung cancer/colorectal cancer/breast cancer) were significantly higher in the examinees without cancer risks, and subgroup analysis according to types of cancer did not indicate significant correlations either. The matched case–control study evaluating seeking bias indicated that a significant proportion of the examinees with cancer risks had undergone prior cancer screening at other institutions. Our study indicated that there was significant seeking bias for prior screening of examinees, with this accounting for the fact that this study did not find a significant correlation between cancer risks and cancer detection rates. The results of our study indicated that PET cancer screening can provide high cancer detection rates.

To determine the usefulness of positron emission tomography (PET) with (11)C-acetate (AC) for imaging lung adenocarcinoma and evaluating its tumor aggressiveness, AC- and (18)F-fluorodeoxyglucose (FDG)-PET were compared.One hundred and sixty-nine adenocarcinomas with clinical stage IA and 53 benign nodules were examined by both AC- and FDG-PET before surgery. The sensitivity and specificity for discriminating benign/adenocarcinoma were compared between AC- and FDG-PET. The AC and FDG uptakes were examined to determine the relationship with tumor aggressiveness, i.e., pathological tumor stage, lymphatic, vascular, or pleural involvement, and proliferative activity determined by Ki-67 staining score.While the sensitivity of AC-PET was significantly higher than FDG-PET for bronchioloalveolar carcinoma (BAC) and well-differentiated (W/D) adenocarcinoma (p0.001 and 0.006, respectively), there was no significant difference for moderately or poorly differentiated adenocarcinoma. The specificity was not different between them. While FDG uptakes were significantly higher in tumors with pathological advanced stages or those with lymphatic, vascular and/or pleural involvements than in tumors with pathological stage IA or those without these tumor involvements (p = 0.04 to p0.001), AC uptake did not show significant differences between the respective sub-groups except according to the tumor stage. While both AC and FDG uptakes showed a significant correlation with Ki-67 staining scores (p = 0.03 and p0.001, respectively), the correlation coefficient of former was lower than that of latter (p = 0.07).While AC-PET can image BAC and W/D adenocarcinoma with a higher sensitivity than FDG-PET, it cannot evaluate tumor aggressiveness of clinical stage IA lung adenocarcinoma as well as FDG-PET.

BACKGROUND: The objective of this study was to clarify the usefulness of positron emission tomography (PET) using18F-fluorodeoxyglucose (FDG) and carbon 11-labeled acetate (AC) for predicting the histologic types and tumor invasiveness of thymoma in a multicenter study. METHODS: Forty thymomas were examined using both FDG-PET and AC-PET before surgery. The histologic types were type A in 1 thymoma, type AB in 12 thymomas, type B1 in 11 thymomas, type B2 in 7 thymomas, type B3 in 6 thymomas, and type C in 3 thymomas. Tumor invasiveness was assessed by pathologic tumor stage and was identified as stage I in 17 tumors, stage II in 17 tumors, stage III in 4 tumors, and stage IV in 2 tumors. FDG and AC uptake was measured as the maximum standard uptake value (SUV). RESULTS: The FDG-SUV in type C thymomas was significantly higher than that in the other types (A-B3; P = .001 – P = .048). The AC-SUV in type A/AB thymomas was significantly higher than that in the other tumor types (B1-C; P < .001 – P = .002). All 3 type C tumors had an FDG-SUV ≥6.3, and all 13 type A/AB tumors had an FDG-SUV

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.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.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.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 (p0.005) 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.

Objective: We analyzed the characteristics of advantages of positron emission tomography(PET) over computed tomography (CT) for N-staging in lung cancer patients.Methods: Preoperative PET and CT scans were performed for 2057 lymph nodestations in205 patients with peripheral-type lung cancer. The advantages of PET over CT for N-stagingwere analyzed among lymph node locations and histological subtypes.Results: The pathological N-stages were N0 in 143 patients, N1 in 31, N2 in 24 and N3in 7. PET was able to diagnose N0, N2 and N3 diseases more accurately than CT (P ¼ 0.03,0.01 and 0.02, respectively), but there was no significant difference between the two modal-ities for N1 disease. In the upper mediastinal lymph node stations, both false-negative andfalse-positive were significantly less frequent with PET than with CT (P ¼ 0.001). In the lowermediastinal and supra clavicle lymph nodes, PET showed a lower frequency of false-negativethan CT (P ¼ 0.04 and 0.003, respectively), but there was no significant difference in the fre-quency of false-positive between the two modalities. Among histological types, PET couldstage adenocarcinoma with less frequent false-negative and squamous cell carcinoma withless frequent false-positive than CT (P ¼ 0.02 and 0.005, respectively).Conclusion: For N-staging, PET was superior to CT for the following: (1) more accurate forN0, N2 and N3 diseases but not for N1; (2) lower frequency of false-positive in the uppermediastinal nodes; and (3) lower frequencies of false-negative in adenocarcinoma and false-positive in squamous cell carcinoma. Recognizing these advantages of PET could make theN-staging of lung cancer more accurate.Key words: positron emission tomography – computed tomography – lymph node stage – lungcancer – adenocarcinoma

Background The influence of heart rate on detectability and reproducibility of multislice computed tomography (MSCT) for measuring coronary calcium score was evaluated using pulsating calcified mock-vessels and compared with electron beam tomography (EBT). Materials and methods Four calcified mock-vessels with 200–350 HU were made to pulsate at a rate of 40–80 beat/min. Retrospective ECG-gating MSCT (Light Speed Ultra 16) scanning with 0.625 mm slice-thickness was performed twice at each pulsation rate. For comparison, EBT (Imatron C150 XP) was performed with 3 and 1.5 mm beam collimation with prospective ECG-gating and calcium scores were measured. Results The comparison revealed that MSCT did not have better reproducibility than EBT, but the calcium scores with MSCT were less influenced by pulsation rates than those with EBT. Especially in mild calcification, the calcium scores decreased with EBT with 3 mm beam collimation with increasing pulsation rate, but the scores were stable in any rate with MSCT. Conclusion MSCT effectively detects coronary calcification, especially mild calcification, without being influenced by heart rate. This is accomplished by reducing the partial volume effect in the through plane using sub millimeter slice thickness, and using appropriate reconstruction methods, which improve temporal resolution.

Objective: To predict a malignant grade of lung cancer by fluorodeoxyglucose positron emission tomography (FDG-PET) scanning, we investigated the correlation between FDG uptake and pathological tumor stage, proliferative activities determined by Ki-67 and cyclin D1, and an alteration of p53, in clinical stage (c-stage) IA lung adenocarcinomas. Methods: FDG-PET was performed for 71 patients with c-stage IA lung adenocarcinomas. FDG uptake was measured by a contrast ratio (CR) between the tumor and contralateral lung. Ki-67, cyclin D1 and p53 staining scores were examined by immunohistochemistry. Results: The lesions with ground-glass opacity were found in 26 patients, and solid lesions in 45 by computed tomography. The pathological tumor stages (p-stage) were stage IA in 59 and more advanced stages in 12. The latter had significantly higher CR value than the former (P < 0.001). Patients with CR ≥ 0.55 could be predicted to be at advanced tumor stages, with a sensitivity of 0.83 and a specificity of 0.82. The CR and staining scores of Ki-67 were significantly correlated with each other (P < 0.0001), and both the values were significantly higher in advanced tumor stages than in p-stage IA, and were also significantly higher in tumors with intratumoral lymphatic, vascular and pleural involvements than in those without such features (P < 0.05-0.0001). Conclusions: In c-stage IA lung adenocarcinomas, the FDG uptake can predict p-stage and tumor proliferative activity determined by Ki-67. For c-stage IA lung adenocarcinomas showing CR ≥ 0.55, mediastinoscopy or neoadjuvant chemotherapy is indicated.

BACKGROUND. [18F]Fluoro-2-deoxyglucose uptake on positron emission tomography (FDG-PET) has been frequently used for diagnosis and staging of lung cancer. The prognostic significance of FDG uptake on PET was evaluated in patients with pathologic Stage I lung adenocarcinoma (tumor stages were based on the TNM classification of the International Union Against Cancer). METHODS. Disease-free survival of 98 patients with pathologic Stage I lung adenocarcinoma who were treated by curative resection was examined in relation to sex, age, histologic grade of differentiation, surgical procedure, tumor stage, and FDG uptake measured as the maximum standardized uptake value (SUV). RESULTS. Sixty-three patients were had Stage IA disease and 35 patients had Stage IB disease. Six patients each with Stage IA and Stage IB disease developed disease recurrence after a mean postsurgical follow-up period of 31 months. Ten (23%) of the 43 patients with SUV ≥ 3.3 developed a recurrence compared with 2 (4%) of the 55 patients with SUV < 3.3 (P = .020). Ten (20%) of the 51 patients with moderately or poorly differentiated adenocarcinoma developed disease recurrence, compared with 2 (4%) of the 47 patients with well-differentiated adenocarcinoma (P = .056). Multivariate analysis demonstrated that histologic grade of differentiation was not correlated with the frequency of tumor recurrence (P = .286), whereas SUV was found to be marginally correlated (P = .079). CONCLUSIONS. FDG uptake appears to be predictive of disease-free survival in patients with Stage I lung adenocarcinoma. FDG uptake could yield important information for determining the likely value of postoperative adjuvant chemotherapy in such patients. Cancer 2006. © 2006 American Cancer Society.

In parallel with the increase in the number of institutions having PET facilities, the number of nurse working in these facilities has also increased, and the issue of occupational radiation exposure has assumed ever greater importance. In our clinic, since nurses have started to administer FDG intravenous injections, their annual radiation exposure has amounted to 4.8-7.1 mSv. To reduce their annual radiation exposure to less than 5 mSv, we identified sources of increased exposure and considered countermeasures based on this information. By implementing countermeasures such as improvements in daily working conditions and ways to avoid various troubles, it was possible to reduce the annual radiation exposure of all nurses to less than 5 mSv. Our experience demonstrates that to provide a working environment with a minimum of occupational radiation exposure, educational training and enhancement of knowledge and technical skills are vital.

近年, FDG-PET検査は医用画像診断において, 非常に重要な方法になってきた。西台クリニック画像診断センターでは, 開設当時のFDG-PET検査は1日数件であったが, 現在では, 1日40件ほどの検査を5台の装置で行っている。患者数及びFDG-PET検査数の増加に伴う職業被ばく量増加を抑えるために著者らは以下の点を改善した。すなわちFDG-PET検査後の検査結果説明時間の短縮, 自動注入器の導入, PET診療に携わる職員の増加である。特にFDGの注射筒内放射能の正確な測定が可能な自動注入器を用いることにより, 注射室における職員の被ばく量の顕著な減少が見られた。自動注入器導入前後の職業被ばく量は1検査あたり, それぞれ8.55μSv, 1.3μSvであった。これらの改善策は, 患者数及びFDG-PET検査数増加に伴う職業被ばくの低減に非常に有効であったと考えられる。

Background Positron-emission tomography (PET) with 18 F-fluorodeoxy-glucose (FDG) frequently gives false-negative results for well-differentiated adenocarcinomas of the lung, especially, those with ground-glass opacity images. Recently, PET with 11 C-acetate (AC) has been reported to detect slow-growing tumors that have failed to be identified by FDG-PET, such as well-differentiated hepatocellular carcinomas and prostate cancers. To determine the usefulness of AC-PET in detecting well-differentiated adenocarcinomas of the lung, we performed both AC-PET and FDG-PET on pulmonary nodules with ground-glass opacity images on computed tomography (CT). Methods Fifty-four pulmonary nodules 1 to 3 cm in size, which showed ground-glass opacity images over their whole or peripheral area on CT, were examined by both AC-PET and FDG-PET. Results Thirty-seven nodules were adenocarcinoma of the lung, while 17 were inflammatory. Of the 37 adenocarcinomas, 19 (51%) were positively identified by AC-PET and 14 (38%) by FDG-PET. Of the 23 adenocarcinomas which were not identified by FDG-PET, 8 (35%) were positively identified by AC-PET; all were well-differentiated adenocarcinomas. Of the 17 inflammatory nodules, 8 were chronic and 9 were acute ones. While none of the 8 chronic inflammatory nodules were identified by either technique, 9 acute ones showed a variety of the results with AC- and FDG-PET. Conclusions AC-PET detected approximately one third of well-differentiated adenocarcinomas of the lung which were not identified by FDG-PET. AC-PET could be useful to diagnose pulmonary nodules with ground-glass opacity images which were not identified by FDG-PET.

PETは核医学検査法の一つであり, 日常に用いられている単光子γ線を利用したシンチグラフィやSPECTなど従来の検査法と大差はないが, 優れた解像力および定量性を持っているため注目を浴びている。特に近年, FDG-PETは各種の癌の診断に用いられ, 1回の検査で全身の癌の検索が可能なため検診にまで利用が広まっている。これまでFDG-PETの癌診断における有用性は, 良・悪性の鑑別, ステージ診断, 再発・転移の検索, 原発巣の検索, 治療効果の判定, 予後の予測などに応用されている。2002年4月からはわが国でも10種類の腫瘍が保険適用になった。また医療改革を背景にビジネスとして自由診療によるPET検診事業が続々と登場してきている。しかし, ポジトロン製剤が短半減期であるために院内に自前のサイクロトロンを設置し, 合成装置を使って放射性薬剤を製造し, 品質をチェックする薬剤師などのスタッフを揃えねばならないという人材的, 経済的制約がある。また, FDG-PETは万能な検査法ではなく, FDG陰性癌もあることを認識して他の形態診断法を参考に診断すべきである。今後, PET/CT装置や新しい放射性医薬品などの開発が実現すればさらに腫瘍PETの臨床での有用性は増し, 日常の腫瘍診断には必須の診断法になると思われる。

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 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.

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 Conclusion: Pulmonary nodules which are less than 1 cm in size or show GGO images on CT cannot be evaluated accurately by PET.

FDG-PETによる婦人科悪性腫瘍の診断成績についての全国アンケート調査を行い, 5施設から計304症例 (ステージング122例, 再発診断182例) のデータが寄せられた。FDG-PETは治療前のステージング・再発診断において高い診断能を示し, しばしばCTやMRIといった一般画像診断法に優る有用な情報を与えた。FDG-PETによりステージングでは10.7%の症例, 再発診断では33.9%の症例で未知の病変が発見され, それぞれ8.9%, 35.1%の症例で治療方針が変更となった。特に画像診断で再発が断定的でない群, 再発が疑われるが画像診断で病変が明らかでない群でFDG-PETが有用な情報を提供することが示され, 不必要な手術や侵襲的手技が回避され, 入院期間が短縮されるといった医療経済効果も期待できると考えられた。

We prepared 5-HT 1A receptor ligands ( S )- N -{[1-(2-phenylethyl)pyrrolidin-2-yl]methyl}-3-[ 11 C]methylthiobenzamide ([ 11 C]( 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.

Several studies have shown that fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is not useful for the diagnosis of thymoma. We describe 3 patients with thymoma who underwent both FDG-PET and carbon-11 (11C) acetate (AC)-PET. Although all three thymomas were successfully imaged by AC-PET, one of the thymomas was not imaged by FDG-PET. These results suggest that AC-PET may have a potentially important role in the diagnosis of thymoma. This is the first report of the use of AC-PET for diagnostic imaging of thymoma.

Erdheim-Chester disease is a rare histiocytic disorder characterized by foamy histiocytes and Tuton giant cells that primarily infiltrate long bones, orbits, retroperitoneal space and lungs. Radiol...

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.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.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.The FDG-PET screening program in Japan detected lung cancer at an early stage.

Lactate dehydrogenase (LDH) levels sometimes act as a good index of response to the treatment of malignant lymphoma. The cause of increases in LDH levels during chemotherapy with recombinant granulocyte colony-stimulating factor (rG-CSF) is not always clear, i.e. whether or not these increases are because of the disease activity or are a side effect of rG-CSF therapy. In this study we evaluated the changes in LDH levels during chemotherapy supported by rG-CSF in patients with malignant lymphoma. A total of 128 courses of rG-CSF chemotherapy were administered to 42 patients with malignant lymphoma. 87 (66%) of these treatment courses were associated with abnormalities in LDH levels, white blood cell count (WBC) and/or alkaline phosphatase (ALP) levels. We found significant correlations between the dose of rG-CSF and the frequency of ALP and WBC, but not LDH, abnormalities. Increases in LDH levels during chemotherapy were more frequently seen in patients who had elevated pretreatment LDH levels. Although increases in LDH levels may be a side effect of rG-CSF therapy, we must be aware of the probability that they may represent the activity of malignant lymphoma, especially in patients with increased pretreatment LDH levels.

To evaluate the usefulness of FDG-PET as a predictor of prognosis, 34 patients with untreated malignant lymphoma in the head and neck region were studied. After FDG-PET and treatment, they were observed from 15 to 50 months. Tumors which were aggressive and resistant to treatment tended to show high uptake of FDG. The survival rate of patients with high uptake of FDG, DARor = 8, was lower than the rate of the other patients. It is considered to be useful to add FDG uptake of the tumor to other prognostic factors for predicting the prognosis.

The aim of this study was to estimate radiation exposure and evaluate the risks and benefits of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in cancer screening. A nationwide survey of FDG-PET cancer screening was conducted in 2006, and the results were analyzed with a common index, “extension/shortening of the average life expectancy.” The average estimated effective dose was 4.4 mSv (male 4.7 mSv; female 4.0 mSv) for dedicated PET and 13.5 mSv (male 14.2 mSv; female 12.8 mSv) for PET/computed tomography (CT). The risk–benefit break-even age from the viewpoint of radiation exposure was in the 40s for men and 30s for women for dedicated PET and in the 50s for men and 50s (variable injection dose) or 60s (constant injection dose) for women for PET/CT. FDG-PET cancer screening is beneficial for examinees above the break-even ages. The risks and benefits should be explained to examinees because of the larger radiation used in cancer FDG-PET screening compared with other X-ray tests.

The most distinctive feature of FDG-PET cancer screening program is the ability to find various kinds of malignant neoplasms in a single test. The aim of this survey is to clarify the range and frequency of various malignant neoplasms detected by FDG-PET cancer screening performed in Japan."FDG-PET 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. This survey was based on a questionnaire regarding FDG-PET cancer screening. We analyzed the situation of 9 less frequently found malignant neoplasms including malignant lymphoma, malignancy of head and neck, esophagus, hepatobiliary and gallbladder, pancreas, kidney, cervical and uterine, ovary, and bladder.The detailed information of subjects with the suspected 9 kinds of malignant neoplasms mentioned above in the FDG-PET cancer screening program was studied in a total of 1,219 cases from 212 facilities. A statistical significance between PET/CT and PET was found in relative sensitivity and PPV for renal cell cancer. Malignant lymphoma was frequently of indolent type, suspected head and neck cancers had many false-positive results, and pancreatic cancer detected in this program was often in the advanced stage even in asymptomatic subjects. The recommendation of combined screening modality to PET or PET/CT was as follows: gastric endoscopy for assessing early esophageal cancer; abdominal ultrasound for screening hepatobiliary and gallbladder cancer; pelvic magnetic resonance imaging for assessing gynecological and pelvic cancers; and the CA125 blood test for screening ovarian cancer. Delayed image was helpful depending on the type of suspected malignant neoplasm.We analyzed various types of malignant neoplasms detected by the FDG-PET cancer screening program and presented recommended combination of examinations to cover FDG-PET and PET/CT.

Technetium-99m-HMPAO (Tc-99m-HMPAO) labeled leukocyte imaging was carried out in 19 patients at 3-5 hr after reinjection. There were no side effects noted. Tc-99m leukocyte images showed gall bladder, colon, kidney, and urinary bladder activity in normal distribution as a result of excretion of the eluted Tc-99m complex. They yielded a sensitivity of 93%, a specificity of 100% and an accuracy of 95%. They were correctly positive in 14 out of 19 cases. But one false negative case was seen in a patient with pyonephrosis showing a lack of renal function with decreased renal blood flow. It was concluded that they have some advantages over In-111 leukocyte images, but we have to consider the fact that the ureteral obstruction or the lack of renal function with decreased renal blood flow may result in a false positive or a false negative case.

From 1975 through 1988, nine patients with locally confined nasal non-Hodgkin's lymphoma (NHL) were treated with radiation therapy in the Department of Radiology, Chiba University Hospital. Immunohistochemical study disclosed that all NHL's have T-lineage. Additionally, unique histological pictures of polymorphism, angiodestruction, and necrosis were seen in most of cases. These three findings are the histological features of polymorphic reticulosis (PMR), which is the main cause of lethal midline granuloma and has recently been shown to belong to T-cell malignancy. Therefore, it is concluded that the nasal T-cell NHL and PMR are really a single disease entity. The predominance of the T-cell lymphoma in the nasal cavity as well as its histological distinctness clearly indicate that the head and neck extranodal NHL cannot be discussed together. Although the disorder was considered to be locally limited at presentation, only 3 of the 9 patients with nasal NHL could be induced into long-term remission with involved field radiotherapy. The distant extranodal spread was the primary cause of failure. Multimodality treatment using intensive chemotherapy might improve the prognosis of nasal NHL.

95症例, 108検査において15Oを用いて標識されたC15O2, 15O2, C15Oガス (15O標識ガス剤) によるPET検査の臨床的有効性および安全性について検討した。全例において本剤に起因する副作用は認められず, 高い安全性が示された。全体の79%の検査で本検査は「有効」以上と判定され, 「無効」の判定の割合は1%であった。全体の80%の例で「きわめて有用」あるいは「有用」と判定され, 「やや有用」を加えると99%となり本検査の高い有用性が示された。

A higher uptake of radiocolloid in a splenic tumor than in the rest of the spleen was observed in a 17-year-old boy. The pathologic diagnosis of the surgically resected tumor was hamartoma composed of anomalous mixtures of splenic elements, and radiocolloid was considered to be distributed to reticuloendothelial cells in the tumor. Radiocolloid scintigraphy, which can demonstrate the function of the reticuloendothelial system, is helpful in the diagnosis of splenic hamartoma.

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.

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 ¼ 18), benign (n ¼ 21), and physiological FDG uptake (n ¼ 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.

The aim of this study is to survey the situation of 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening in Japan and to describe its performance profile. “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. 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). 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.

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.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.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).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.

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.

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.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.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).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.

Positron emission tomography (PET) with 11 C-acetate has been recently reported in detection of slow-growing tumors, such as well-differentiated adenocarcinomas of the lung, which are often negative with 18 F-fluorodeoxyglucose (FDG) PET. Here we present findings of acetate-PET and FDG-PET in a case of adenocarcinoma that was comprised of peripheral ground glass opacity and solid central components, and was histologically comprised of both a well-differentiated and a moderately-differentiated adenocarcinoma, respectively. Acetate-PET was positive in both components, whereas FDG-PET was only positive in the solid central component. The present case demonstrates the figurative findings of acetate-PET and FDG-PET in lung adenocarcinoma.

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.

Epithelial-myoepithelial carcinoma (EMC) is a rare low-grade malignant salivary gland neoplasm typically found in the parotid gland. This report describes a case of EMC that arose from the submandibular gland, and gives special emphasis to the preoperative diagnostic value of positron emission tomography (PET) in combination with computed tomography (CT) and magnetic resonance imaging (MRI). Although a preoperative diagnostically specific image of EMC could not be established, the malignant nature of this tumor was detected by these combined examinations.

We report two patients with non-small cell lung cancer who had a pathologically complete response after neoadjuvant chemoradiotherapy, although they had positive [ 1 8 F]fluoro-deoxy-glucose positron emission tomography ([ 1 8 F]FDG-PET) scans. They underwent concurrent chemoradiotherapy, which resulted in a partial response determined by computed tomography (CT). While [ 1 8 F]FDG-PET after chemoradiotherapy was positive, pathological examination showed that the tumors were fibrotic lesions with infiltration of lymphocytes and macrophages, with the appearance of metaplastic epithelial cells. The reasons for the false-positive results on [ 1 8 F]FDG-PET were considered to be the high uptake of FDG in non-neoplastic inflammatory cellular elements, i.e. macrophages, lymphocytes and metaplastic epithelial cells, and squamous metaplasia induced by chemoradiotherapy. Although several studies demonstrated that [ 1 8 F]FDG-PETcould predict the response of neoadjuvant treatment of non-small cell lung cancer, one should bear in mind that false-positive results could be observed in pathological complete response of non-small cell lung cancer after neoadjuvant chemoradiotherapy.

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 (p0.01-0.05). Lung cancers1 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.

While visual assessment is the simplest way to evaluate positron emission tomography (PET) with fluorodeoxyglucose (FDG), faintly positive nodules are often difficult to evaluate. We performed visual and semiquantitative analyses of pulmonary nodules from 1 to 3 cm in size to determine the optimal method of analysis for PET data, especially for faintly positive nodules on visual assessment.Positron emission tomography data were analyzed for 161 pulmonary nodules from 1 to 3 cm in size (108 malignant and 53 benign nodules). On visual assessment, FDG uptake by the nodules was classified into three grades in comparison with mediastinal blood pool, (ie, definitely positive, faintly positive, and negative). In addition, FDG uptake was measured by the standard uptake value (SUV), the contrast ratio to the contralateral lung (CR-lung), and the contrast ratio to the cerebellum (CR-brain). Cut-off values for each variable were determined from receiver operating characteristics (ROC) curves, and the values were 2.5 for the SUV, 0.4 for the CR-lung, and 0.25 for the CR-brain. Nodules with FDG uptake above these cut-off values were defined as positive in each method.Visual assessment showed definitely positive for 80 nodules (64 malignant and 16 benign), faintly positive for 22 (17 malignant and 5 benign), and negative for 59 nodules (27 malignant and 32 benign). In the 139 nodules that were definitely positive or negative by visual assessment, there were no significant differences of sensitivity and specificity among the four methods (visual assessment, SUV, CR-lung, and CR-brain). In the 17 malignant nodules that were faintly positive, the SUV did not detect any true-positive nodules, but the CR-lung and CR-brain showed 9 and 5 true-positive nodules, respectively, resulting in a significantly higher sensitivity than the SUV (p0.001 and p = 0.02, respectively). Fifteen of 17 faintly positive malignant nodules (88%) were histologically well- or moderately-differentiated adenocarcinoma.The semiquantitative methods (SUV, CR-lung, and CR-brain) do not improve the efficacy of visual assessment alone for nodules graded as definitely positive or negative. However, faintly positive nodules on visual assessment should be evaluated by the CR-lung or CR-brain rather than the SUV, and are often differentiated adenocarcinomas.

BackgroundWe 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.MethodsPreoperative 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.ResultsThe 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.ConclusionsAlthough 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.

BACKGROUND Positron emission tomography (PET) with 2-deoxy-2-fluoro[18F]-D-glucose (FDG) can provide quantitative information about tumor glucose metabolism. The prognostic value of this technique was evaluated for breast carcinoma patients. METHODS FDG PET was performed on 70 patients with primary breast carcinoma, and the differential absorption ratio (DAR) was calculated as an index of FDG uptake. Overall and relapse free survival curves were created by the Kaplan-Meier method, and differences between the curves were analyzed with the log rank test. For multivariate analysis, the Cox proportional hazards regression model was used. RESULTS The mean DAR was 2.61 ± 1.61 standard deviation (range, 0.65-9.39). According to the grade of DAR, patients were then classified into high DAR (≥3.0) and low DAR (