Ratio of Mediastinal Lymph Node SUV to Primary Tumor SUV in 18F-FDG PET/CT for Nodal Staging in Non-Small-Cell Lung Cancer.

PURPOSE: Following determination of the maximum standardized uptake values (SUVmax) of the mediastinal lymph nodes (SUV-LN) and of the primary tumor (SUV-T) on 18F-FDG PET/CT in patients with non-small-cell lung cancer (NSCLC), the aim of the study was to determine the value of the SUV-LN/SUV-T ratio in lymph node staging in comparison with that of SUV-LN. METHODS: We retrospectively reviewed a total of 289 mediastinal lymph node stations from 98 patients with NSCLC who were examined preoperatively for staging and subsequently underwent pathologic studies of the mediastinal lymph nodes. We determined SUV-LN and SUV-R for each lymph node station on 18F-FDG PET/CT and then classified each station into one of three groups based on SUV-T (low, medium and high SUV-T groups). Diagnostic performance was assessed based on receiver operating characteristic (ROC) curve analysis, and the optimal cut-off values that would best discriminate metastatic from benign lymph nodes were determined for each method. RESULTS: The average of SUV-R of malignant lymph nodes was significantly higher than that of benign lymph nodes (0.79 ± 0.45 vs. 0.36 ± 0.23, P < 0.0001). In the ROC curve analysis, the area under the curve (AUC) of SUV-R was significantly higher than that of SUV-LN in the low SUV-T group (0.885 vs. 0.810, P = 0.019). There were no significant differences between the AUCs of SUV-LN and of SUV-R in the medium and high SUV-T groups. The optimal cut-off value for SUV-R in the low SUV-T group was 0.71 (sensitivity 87.5 %, specificity 85.9 %). CONCLUSIONS: The SUV-R performed well in distinguishing between metastatic and benign lymph nodes. In particular, SUV-R was found to have a better diagnostic performance than SUV-LN in the low SUV-T group.

Fluorine-18 fluorodeoxyglucose positron emission tomography imaging of T-lymphoblastic lymphoma patients.

The purpose of the present study was to evaluate the fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) findings in patients with T-lymphoblastic lymphoma (T-LBL). In total, 9 patients with histopathologically confirmed T-LBL were included in the study. Bone marrow (BM) involvement and leukemic transformation (LT) were evaluated through iliac crest marrow biopsy and peripheral blood blast count. FDG-PET scans were performed at the initial pre-treatment point. Two experienced nuclear medicine physicians evaluated the FDG-PET images by visual analysis and using the maximum standardized uptake values (SUVmax) of the malignant lesions. Overall, 8 out 9 patients presented with BM involvement; 7 showed LT, while 1 showed BM involvement without LT. All involved T-LBL lesions were FDG-avid with variable uptake. The mean SUVmax was 6.4±3.3. T-LBL patients with BM involvement showed diffuse or nodular marrow uptake. In addition, all the patients with LT showed diffuse marrow FDG activity. However, the patient with BM involvement but no LT showed nodular FDG uptake in the marrow. In conclusion, the present study indicates that it is possible to use FDG-PET for the evaluation of the disease extent of T-LBL. Furthermore, the imaging technique could provide a diagnostic clue for determining BM involvement or LT.

Correlation between Semi-Quantitative (18)F-FDG PET/CT Parameters and Ki-67 Expression in Small Cell Lung Cancer.

PURPOSE: The aim of this study was to evaluate the relationship between semiquantitative parameters on (18)F-FDG PET/CT including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and the expression level of Ki-67 in small-cell lung cancer (SCLC). METHODS: Ninety-four consecutive patients with SCLC were enrolled in this study. They underwent (18)F-FDG PET/CT for initial evaluation of SCLC, and we measured SUVmax, avgSUVmean, MTVsum, and TLGtotal on (18)F-FDG PET/CT images. The protein expression of Ki-67 was examined by immunohistochemical staining. RESULTS: Significant correlations were found between the MTVsum and Ki-67 labeling index (r = 0.254, p = 0.014) and the TLGtotal and Ki-67 labeling index (r = 0.239, p = 0.020). No correlation was found between the SUVmax and Ki-67 labeling index (r = 0.116, p = 0.264) and the avgSUVmean and Ki-67 labeling index (r = 0.031, p = 0.770). Dividing the Ki-67 expression level into three categories, it was suggested that increasing Ki-67 expression level caused a stepwise increase in the MTVsum and TLGtotal. (p = 0.028 and 0.039, respectively), but not the SUVmax and avgSUVmean (p = 0.526 and 0.729, respectively). CONCLUSION: In conclusion, the volume-based parameters of (18)F-FDG PET/CT correlate with immunohistochemical staining of Ki-67 in SCLC. Measurement of the MTVsum and TLGtotal by (18)F-FDG PET/CT might be a simple, noninvasive, and useful method to determine the proliferative potential of cancer cells.

Semi-Quantitative Analysis of Post-Transarterial Radioembolization (90)Y Microsphere Positron Emission Tomography Combined with Computed Tomography (PET/CT) Images in Advanced Liver Malignancy: Comparison With (99m)Tc Macroaggregated Albumin (MAA) Single Photon Emission Computed Tomography (SPECT).

OBJECTIVES: The purpose of this study is to evaluate the correlation between pretreatment planning technetium-99m ((99m)Tc) macroaggregated albumin (MAA) SPECT images and posttreatment transarterial radioembolization (TARE) yttirum-90 ((90)Y) PET/CT images by comparing the ratios of tumor-to-normal liver counts. METHODS: Fifty-two patients with advanced hepatic malignancy who underwent (90)Y microsphere radioembolization from January 2010 to December 2012 were retrospectively reviewed. Patients had undergone (99m)Tc MAA intraarterial injection SPECT for a pretreatment evaluation of microsphere distribution and therapy planning. After the administration of (90)Y microspheres, the patients underwent posttreatment (90)Y PET/CT within 24 h. For semiquantitative analysis, the tumor-to-normal uptake ratios in (90)Y PET/CT (TNR-yp) and (99m)Tc MAA SPECT (TNR-ms) as well as the tumor volumes measured in angiographic CT were obtained and analyzed. The relationship of TNR-yp and TNR-ms was evaluated by Spearman's rank correlation and Wilcoxon's matched pairs test. RESULTS: In a total of 79 lesions of 52 patients, the distribution of microspheres was well demonstrated in both the SPECT and PET/CT images. A good correlation was observed of between TNR-ms and TNR-yp (rho value = 0.648, p < 0.001). The TNR-yp (median 2.78, interquartile range 2.43) tend to show significantly higher values than TNR-ms (median 2.49, interquartile range of 1.55) (p = 0.012). The TNR-yp showed weak correlation with tumor volume (rho = 0.230, p = 0.041). CONCLUSIONS: The (99m)Tc MAA SPECT showed a good correlation with (90)Y PET/CT in TNR values, suggesting that (99m)Tc MAA can be used as an adequate pretreatment evaluation method. However, the (99m)Tc MAA SPECT image consistently shows lower TNR values compared to (90)Y PET/CT, which means the possibility of underestimation of tumorous uptake in the partition dosimetry model using (99m)Tc MAA SPECT. Considering that (99m)Tc MAA is the only clinically available surrogate marker for distribution of microsphere, we recommend measurement of tumorous uptake using (90)Y PET/CT should be included routinely in the posttherapeutic evaluation.

Usefulness of (18)F-FDG PET/CT to Detect Metastatic Mucinous Adenocarcinoma Within an Inguinal Hernia.

Metastatic mucinous adenocarcinoma in an inguinal hernia is a rare disease and the image findings of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT) are little known. Here, we introduce a 57-year-old man with metastatic mucinous adenocarcinoma in an inguinal hernia. On initial (18)F-FDG PET/CT, hypermetabolism was observed in mucinous adenocarcinoma of the cecum, and adenocarcinomas of the transverse and ascending colon, respectively. Follow-up (18)F-FDG PET/CT revealed newly developed multiple hypermetabolism in peritoneal seeding masses and nodules in the pelvic cavity and scrotum. Peritoneal carcinomatosis in the right pelvic side wall was extended to the incarcerated peritoneum and mesentery in the right inguinoscrotal hernia.(18)F-FDG PET/CT was useful to reveal unexpected peritoneal seeding within the inguinal hernia. Also, this case demonstrated that metastatic mucinous adenocarcinomas had variably intense FDG uptake.

Predictive Role of Functional Visceral Fat Activity Assessed by Preoperative F-18 FDG PET/CT for Regional Lymph Node or Distant Metastasis in Patients with Colorectal Cancer.

OBJECTIVES: To investigate the role of functional visceral fat activity assessed by preoperative F-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in colorectal cancer (CRC) for predicting regional lymph node (LN) or distant metastasis. METHOD: We evaluated 131 patients with newly diagnosed CRC. They all underwent pre-operative 18F-FDG PET/CT and surgery. Functional fat activity was measured by maximum standardized uptake value (SUVmax) using 18F-FDG PET/CT. Functional visceral fat activity was measured by SUVmax of visceral fat/SUVmax of subcutaneous fat (V/S) ratio. Mann-Whitney U test, χ2 test, Fisher's exact test, receiver-operating characteristic (ROC) analysis, Spearrman's correlation coefficient, and uni- and multivariate logistic regression statistical analyses were done. RESULTS: Patients with higher V/S ratio displayed a significantly higher rate of regional LN (p = 0.004) and distant metastasis (p<0.001). In addition, V/S ratio was the only factor that was significantly associated with distant metastasis. An optimal cut-off V/S ratio of 1.88 was proposed for predicting distant metastasis with a sensitivity of 84.6% and specificity of 78.8% (area under the curve: 0.86; p<0.0001). CONCLUSION: Functional visceral fat activity is significantly associated with distant metastasis in CRC patients. Furthermore, V/S ratio can be useful as a complementary factor in predicting distant metastasis.

Detection of metastatic tumors after γ-irradiation using longitudinal molecular imaging and gene expression profiling of metastatic tumor nodules.

A few recent reports have indicated that metastatic growth of several human cancer cells could be promoted by radiotherapy. C6-L cells expressing the firefly luciferase (fLuc) gene were implanted subcutaneously into the right thigh of BALB/c nu/nu mice. C6-L xenograft mice were treated locally with 50-Gy γ-irradiation (γ-IR) in five 10-Gy fractions. Metastatic tumors were evaluated after γ-IR by imaging techniques. Total RNA from non-irradiated primary tumor (NRPT), γ-irradiated primary tumor (RPT), and three metastatic lung nodule was isolated and analyzed by microarray. Metastatic lung nodules were detected by BLI and PET/CT after 6-9 weeks of γ-IR in 6 (17.1%) of the 35 mice. The images clearly demonstrated high [18F]FLT and [18F]FDG uptake into metastatic lung nodules. Whole mRNA expression patterns were analyzed by microarray to elucidate the changes among NRPT, RPT and metastatic lung nodules after γ-IR. In particular, expression changes in the cancer stem cell markers were highly significant in RPT. We observed the metastatic tumors after γ-IR in a tumor-bearing animal model using molecular imaging methods and analyzed the gene expression profile to elucidate genetic changes after γ-IR.

18F-FDG PET/CT of Bronchial Mucous Gland Adenoma.

Bronchial mucous gland adenoma is a very rare benign tumor that arises from the bronchial mucous-secreting glands. Its detection and appearance using F-FDG PET/CT has not been well characterized. We present a case of a 59-year-old man with FDG-avid mucous gland adenoma that mimicked lung cancer on F-FDG PET/CT.

Radionuclide imaging in the diagnosis of osteoid osteoma.

Oseteoid osteoma is a well-known type of benign bone-forming tumor, which has previously been diagnosed using plain radiograph imaging. However, diagnosis of osteoid osteoma may be delayed due to ambiguities on plain radiograph images; despite the increasing use of magnetic resonance imaging (MRI), this type of misdiagnosis is not uncommon. The aim of the present study was to evaluate the effectiveness of radionuclide imaging scans for the diagnosis of osteoid osteoma, as this form of imaging was proposed to be a more sensitive test. The characteristics of 18 cases of osteoid osteoma were analyzed based on diagnostic imaging and the time from initial recognition of symptoms by the patient to diagnosis. Diagnostic modalities included plain radiograph, computed tomography (CT), MRI and radionuclide imaging. Among the 18 patients, 14 patients had unique positive findings in plain radiographs. The mean duration between initial cognition of symptoms to the diagnosis for these patients was 5.2 months (range, 3.8-9.3 months). A total of 4 patients exhibited no radiographic abnormalities in the initial plain radiographs and were diagnosed a mean of 18.5 months (range, 17-20 months) following the onset of symptoms. Overall, radionuclide imaging was performed on 16 patients and all of the cases demonstrated positive findings. In these cases, 28.6% of osteoid osteoma patients with clinical indications revealed no abnormal findings in plain radiographs. Therefore, in situations such as these, radionuclide imaging may be a useful indicator for diagnosis, as these results have demonstrated that it positively identified all cases of osteoid osteoma. In addition, the results of the present study indicated that if the radionuclide imaging was positive, CT scan was a more valuable diagnostic tool, whereas if the radionuclide imaging was negative, MRI should be recommended for the diagnosis of other undiscovered disease entities.

The use of fluorine-18 fluorodeoxyglucose positron emission tomography for imaging human motor neuronal activation in the brain.

The present study aimed to visualize human motor neuronal activation in the brain using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), and to develop an FDG-PET procedure for imaging neuronal activation. A male volunteer underwent 20 min periods of rest and motor activation, whilst being assessed using FDG-PET on two consecutive days. The motor task, which involved repetitively grasping and releasing the right hand, was performed during the initial 5 min of the activation period. Subtraction of the rest period signal from the activation PET images was performed using the subtraction ictal single-photon emission computed tomography co-registered to magnetic resonance imaging method. The subtracted image detected activation of the contralateral (left) primary motor cortex, supplementary motor area, and ipsilateral (right) cerebellum. In the present study, FDG-PET detected significantly increased motor-associated activation of the brain in a subject performing a motor task.

Early prediction of pathological complete response in luminal B type neoadjuvant chemotherapy-treated breast cancer patients: comparison between interim 18F-FDG PET/CT and MRI.

PURPOSE: The aim of this study is to justify the effectiveness of interim PET/computed tomography (CT) for predicting pathological complete response (pCR) in luminal B type breast cancer patients and to compare the diagnostic performance of interim PET/CT and MRI. MATERIALS AND METHODS: Twenty-one patients with neoadjuvant chemotherapy (NAC)-treated luminal B type breast cancer were included. All patients underwent PET/CT and MRI at baseline and interim (mid-point). Breast surgery was performed after completion of NAC. Maximum standardized uptake values (SUV(max)) of breast malignant lesions in each PET/CT scan were acquired in each patient. The metabolic response was calculated as follows: ΔSUV (%) = (baseline SUV(max)-interim SUV(max))/baseline SUV(max) × 100 (%). In MRI, the relative size change was calculated as follows: Size change (%) = longest diameter interim MRI-longest diameter baseline MRI/longest diameter baseline MRI × 100 (%). pCR was concluded through the final pathologic specimen after breast surgery. The receiver-operating characteristic analysis was used as a statistical method. RESULTS: Of 21 patients, seven achieved a pCR after surgery. In PET/CT, an optimal cut-off ΔSUV (%) of 69.0% was proposed with a sensitivity of 85.7% and a specificity of 100% (P < 0.0001). In MRI, an optimal cut-off size change (%) was 38.2% with a sensitivity of 64.3% and a specificity of 71.4% (P = 0.29). The area under the curve was 0.92 and 0.65, respectively. PET/CT presented better predictability of the pCR than MRI (P = 0.04). CONCLUSION: In luminal B type NAC-treated breast cancer patients, it is possible to use PET/CT as an early surrogate marker for predicting pCR and it is significantly more predictable for pCR than MRI.

Value of (18)F-FDG PET/CT in the Detection of Ovarian Malignancy.

PURPOSE: Ovarian cancer is a leading cause of gynecologic malignancy. As symptoms of ovarian cancer are nonspecific, only 20 % of ovarian cancers are diagnosed while they are still limited to the ovaries. Thus, early and accurate detection of disease is important for an improved prognosis. For the accurate and effective diagnosis of ovarian malignancy on (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT), we analyzed several parameters, including visual assessment. METHOD: A total of 51 peritoneal lesions in 19 patients who showed ovarian masses with diffuse peritoneal infiltration were enrolled. Twelve patients were confirmed to have ovarian malignancy and seven patients with benign disease by pathologic examination. All patients were examined by (18)F-FDG PET/CT, and an additional 2-h delayed (18)F-FDG PET/CT was also performed for 15 patients with 42 peritoneal lesions. We measured semiquantitative parameters including maximum and mean standardized uptake values (SUVmax, SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) on a 1-h initial (18)F-FDG PET/CT image (Parameter1) and on a 2-h delayed image (Parameter2). Additionally, retention indices of each parameter were calculated, and each parameter among the malignant and benign lesions was compared by Mann-Whitney U test. We also assessed the visual characteristics of each peritoneal lesion, including metabolic extent, intensity, shape, heterogeneity, and total visual score. Associations between visual grades and malignancy were analyzed using linear by linear association methods. Moreover, a receiver operating characteristic (ROC) curve was analyzed to compare the effectiveness of significant parameters. RESULT: In a comparison between the malignant and benign groups in the analysis of 51 total peritoneal lesions, SUVmax1, SUVmean1, and TLG1 showed significant differences. Also, in the analysis of 42 peritoneal lesions that underwent an additional 2-h (18)F-FDG PET/CT examination, SUVmax1,2, SUVmean1,2, TLG2, and the RI of TLG showed significant differences between the malignant and benign groups. MTV did not show significant differences in either the analysis of 51 peritoneal lesions or of 42 lesions. Regarding visual assessments, metabolic intensity, shape, heterogeneity, and total visual score showed an association with malignancy. In the ROC analysis, the AUC of the visual score was larger than the AUC of other parameters in both the analyses of 51 peritoneal lesions and of 42 lesions. CONCLUSION: Although further study with a larger patient population is needed, the visual assessment of (18)F-FDG PET/CT imaging has a primary role in the detection of malignancy in ovarian cancer patients with assistance from other semi-quantitative parameters.

Radioembolization With Yttrium-90 Resin Microspheres in Hepatocellular Carcinoma: A Multicenter Prospective Study.

OBJECTIVES: The aim of this prospective study was to reveal the efficacy and safety of Yttrium-90 (Y) radioembolization in Korean patients with hepatocellular carcinoma (HCC). METHODS: A total of 40 HCC patients were prospectively recruited from 7 centers. The response to treatment was assessed on the basis of the modified Response Evaluation Criteria in Solid Tumors criteria. The time to progression and overall survival were also evaluated, and the assessment of safety was done according to National Cancer Institute Common Terminology Criteria, Version 3.0. RESULTS: Forty-two treatments of Y radioembolization were carried out. Median follow-up was 29 months. At 3 months, the complete response, partial response (PR), and stable disease were seen in 4 (10.0%), 19 (47.5%), and 15 (37.5%) patients, respectively. The response rate was 57.5% (23/40), and disease control rate was 95% (38/40) at 3 months. The response rate at 6 months was 63.9% (23/36), and disease control rate was 83.3% (30/36). The median time to progression was 18 months. During follow-up, 10 HCC-related deaths occurred and the 3-year survival rate was 75%. In 19 patients with Barcelona Clinic Liver Cancer-B stage, the 3-year survival rate was 50%. The tumor number (>5) was the only significant predictor associated with survival. The most common adverse event was abdominal pain of mild to moderate degree, and all the complications were manageable. Twenty-six (65%) patients underwent other treatments such as transarterial chemoembolization because of local progression or remnant viable lesion. CONCLUSIONS: Y radioembolization might be a safe and effective treatment modality in intermediate-stage to advanced-stage HCC.

Detection of increased 64Cu uptake by human copper transporter 1 gene overexpression using PET with 64CuCl2 in human breast cancer xenograft model.

UNLABELLED: Copper is an essential cofactor for a variety of biochemical processes including oxidative phosphorylation, cellular antioxidant activity, and elimination of free radicals. The copper transporter 1 is known to be involved in cellular uptake of copper ions. In this study, we evaluated the utility of human copper transporter 1 (hCTR1) gene as a new reporter gene for (64)Cu PET imaging. METHODS: Human breast cancer cells (MDA-MB-231) were infected with a lentiviral vector constitutively expressing the hCTR1 gene under super cytomegalovirus promoter, and positive clones (MDA-MB-231-hCTR1) were selected. The expression of hCTR1 gene in MDA-MB-231-hCTR1 cells was measured by reverse transcription polymerase chain reaction, Western blot, and (64)Cu uptake assay. To evaluate the cytotoxic effects induced by hCTR1 expression, the dose-dependent cell survival rate after treatment with cisplatin (Cis-diaminedichloroplatinum (II) [CDDP]) was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue dye exclusion. Small-animal PET images were acquired in tumor-bearing mice from 2 to 48 h after an intravenous injection of (64)Cu. RESULTS: The hCTR1 gene expression in MDA-MB-231-hCTR1 cells was confirmed at the RNA and protein expression and the cellular (64)Cu uptake level. MTT assay and trypan blue dye exclusion showed that the cell viability of MDA-MB-231-hCTR1 cells decreased more rapidly than that of MDA-MB-231 cells after treatment with CDDP for 96 or 72 h, respectively. Small-animal PET imaging revealed a higher accumulation of (64)Cu in MDA-MB-231-hCTR1 tumors than in MDA-MB-231 tumors. With respect to the biodistribution data, the percentage injected dose per gram of (64)Cu in the MDA-MB-231 tumors and MDA-MB-231-hCTR1 tumors at 48 h after (64)Cu injection was 2.581 ± 0.254 and 5.373 ± 1.098, respectively. CONCLUSION: An increase in (64)Cu uptake induced by the expression of hCTR1 gene was demonstrated in vivo and in vitro, suggesting the potential use of hCTR1 gene as a new imaging reporter gene for PET with (64)CuCl2.

The role of interim 18F-FDG PET/CT in predicting early response to neoadjuvant chemotherapy in breast cancer.

AIM: The aim of this study was to prove the diagnostic value of interim 18F-Fluorodeoxyglucose-positron-emission tomography combined with computed tomography (PET/CT) scan for predicting pathological complete response (pCR) compared to other factors in neoadjuvant chemotherapy. PATIENTS AND METHODS: Twenty-seven patients with breast cancer were included in this retrospective study. They all underwent scheduled neoadjuvant chemotherapy. Patients underwent PET/CT at baseline, mid-point (interim), and preoperatively (after completion of chemotherapy). The metabolic response was calculated as follows: ΔStandardized uptake value (SUV)(%)=(1st SUV(max)-2nd SUV(max))/1st SUV(max) × 100. RESULTS: The change in SUVmax between baseline and interim PET/CT scans was significantly larger than between interim and preoperative PET/CT scan. An optimal cut-off ΔSUV value of 78.3% was proposed for discriminating patients with pCR from those without pCR. Metabolic CR, defined as a change of SUV(max) greater than the cut-off value, can predict pCR according to univariate analysis (p=0.012; Relative risk (RR)=25.3). Furthermore, metabolic CR was the most powerful factor for predicting pCR than other possible factors according to multivariate analysis (p=0.003). CONCLUSION: It is possible to use interim (18)F-FDG PET-CT as an effective method to predict early response in patients with breast cancer treated with neoadjuvant chemotherapy.

Differential Diagnosis of Patients with Inconclusive Parkinsonian Features Using [(18)F]FP-CIT PET/CT.

PURPOSE: It is often difficult to differentiate parkinsonism, especially when patients show uncertain parkinsonian features. We investigated the usefulness of dopamine transporter (DAT) imaging for the differential diagnosis of inconclusive parkinsonism using [(18)F]FP-CIT PET. METHODS: Twenty-four patients with inconclusive parkinsonian features at initial clinical evaluation and nine healthy controls were studied. Patients consisted of three subgroups: nine patients whose diagnoses were unclear concerning whether they had idiopathic Parkinson's disease or drug-induced parkinsonism ('PD/DIP'), nine patients who fulfilled neither the diagnostic criteria of PD nor of essential tremor ('PD/ET'), and six patients who were alleged to have either PD or atypical parkinsonian syndrome ('PD/APS'). Brain PET images were obtained 120 min after injection of 185 MBq [(18)F]FP-CIT. Imaging results were quantified and compared with follow-up clinical diagnoses. RESULTS: Overall, 11 of 24 patients demonstrated abnormally decreased DAT availability on the PET scans, whereas 13 were normal. PET results could diagnose PD/DIP and PD/ET patients as having PD in six patients, DIP in seven, and ET in five; however, the diagnoses of all six PD/APS patients remained inconclusive. Among 15 patients who obtained a final follow-up diagnosis, the image-based diagnosis was congruent with the follow-up diagnosis in 11 patients. Four unsolved cases had normal DAT availability, but clinically progressed to PD during the follow-up period. CONCLUSION: [(18)F]FP-CIT PET imaging is useful in the differential diagnosis of patients with inconclusive parkinsonian features, except in patients who show atypical features or who eventually progress to PD.

The Clinical Role of Dual-Time-Point (18)F-FDG PET/CT in Differential Diagnosis of the Thyroid Incidentaloma.

Thyroid incidentalomas are common findings during imaging studies including (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) for cancer evaluation. Although the overall incidence of incidental thyroid uptake detected on PET imaging is low, clinical attention should be warranted owing to the high incidence of harboring primary thyroid malignancy. We retrospectively reviewed 2,368 dual-time-point (18)F-FDG PET/CT cases that were undertaken for cancer evaluation from November 2007 to February 2009, to determine the clinical impact of dual-time-point imaging in the differential diagnosis of thyroid incidentalomas. Focal thyroid uptake was identified in 64 PET cases and final diagnosis was clarified with cytology/histology in a total of 27 patients with (18)F-FDG-avid incidental thyroid lesion. The maximum standardized uptake value (SUVmax) of the initial image (SUV1) and SUVmax of the delayed image (SUV2) were determined, and the retention index (RI) was calculated by dividing the difference between SUV2 and SUV1 by SUV1 (i.e., RI = [SUV2 - SUV1]/SUV1 × 100). These indices were compared between patient groups that were proven to have pathologically benign or malignant thyroid lesions. There was no statistically significant difference in SUV1 between benign and malignant lesions. SUV2 and RI of the malignant lesions were significantly higher than the benign lesions. The areas under the ROC curves showed that SUV2 and RI have the ability to discriminate between benign and malignant thyroid lesions. The predictability of dual-time-point PET parameters for thyroid malignancy was assessed by ROC curve analyses. When SUV2 of 3.9 was used as cut-off threshold, malignancy on the pathology could be predicted with a sensitivity of 87.5 % and specificity of 75 %. A thyroid lesion that shows RI greater than 12.5 % could be expected to be malignant (sensitivity 88.9 %, specificity 66.3 %). All malignant lesions showed an increase in SUVmax on the delayed images compared with the initial images. But in the group of benign lesions, 37.5 % (6/16) showed a decrease or no change in SUVmax. Dual-time-point (18)F-FDG PET/CT, obtaining additional images 2 h after injection, seems to be a complementary method for the differentiation between malignancy and benignity of incidental thyroid lesions.

Implication of lymph node metastasis detected on 18F-FDG PET/CT for surgical planning in patients with peripheral intrahepatic cholangiocarcinoma.

OBJECTIVES: Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy after hepatocellular carcinoma. ICC can be divided into 2 types according to their location: peripheral and hilar types. Intense F-FDG uptake on PET was reported in peripheral ICC. However, the usefulness of PET/CT in detecting tumors and predicting prognosis in peripheral ICC has not been fully evaluated. In this study, we evaluated the clinical role of F-FDG PET/CT to predict the recurrence after the curative resection in patients with surgically indicated peripheral ICC. METHODS: Eighteen patients with ICC underwent preoperative CT and F-FDG PET/CT scans. SUVmax of tumor, tumor to normal liver SUV ratio (TNR), lymph node status evaluated by F-FDG PET/CT, tumor and lymph node size measured by CT, vascular invasion confirmed by pathology, and satellite nodules found on CT were compared between 1-year recurrence group and recurrence-free group by chi-square test. RESULTS: Of total 23 measurable lymph nodes, 4 nodes were positive and other 19 nodes were negative or equivocal on CT. Among those 23 nodes, 9 nodes were positive and other 14 nodes were negative on F-FDG PET/CT. The sensitivity and specificity of CT were 20.0% and 86.4%, and those of F-FDG PET/CT were 80.0% and 92.3%. In the comparison between 1-year recurrent and nonrecurrent groups, lymph node metastasis detected on F-FDG PET/CT had statistically positive correlation with the 1-year recurrence after surgical resection (P = 0.02). Other factors showed no statistically significant difference between the groups. CONCLUSION: We found that lymph node metastasis detected on F-FDG PET/CT correlated positively with 1-year recurrence after surgical resection in patients with peripheral ICC.