Yun Jung Choi

The utility of F-18 FDG PET/CT in the evaluation of pancreatic intraductal papillary mucinous neoplasm.

Purpose: To assess the utility of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in evaluating pancreatic intraductal papillary mucinous neoplasm (IPMN). Materials and Methods: We included 31 patients with pancreatic IPMN who underwent F-18 FDG PET/CT and multidetector CT (MDCT). Each pancreatic lesion was classified as benign or malignant. On PET, the maximal standardized uptake value was measured in each pancreatic lesion. Results: PET/CT was superior to MDCT in diagnosing malignant IPMN. All 22 concordant results gave accurate diagnoses. Of 9 discordant results, MDCT misdiagnosed 7 IPMNs, whereas PET/CT misinterpreted 2. Malignant IPMNs showed significantly higher maximal standardized uptake values (mean ± standard deviation, 6.7 ± 3.6) than benign IPMNs (mean ± standard deviation, 2.1 ± 1.0) (P < 0.001). Conclusions: F-18 FDG PET/CT outperformed MDCT in detecting malignant IPMN.

A risk-adapted approach using US features and FNA results in the management of thyroid incidentalomas identified by 18F-FDG PET.

PURPOSEnTo assess the risk of malignancy of thyroid incidentalomas found on 18F-FDG PET/CT by US features and cytologic results, and to evaluate the clinical usage of a combination of US features and cytology for post-FNA management of thyroid incidentalomas on 18F-FDG PET/CT.nnnMATERIALS AND METHODSnFrom September 2006 to December 2008, 132 patients with 134 thyroid incidentalomas detected on 18F-FDG PET/CT who had undergone US and US-FNA were included in this study. We evaluated the malignancy rate of thyroid incidentalomas in different subgroups subdivided by US features and US-FNA cytology results. Several variables were compared between the benign and malignant group.nnnRESULTSnThe risk of malignancy was 58.2u200a% (78/132) in thyroid incidentalomas on 18F-FDG PET/CT. Age, gender, and tumor size were not significantly different between the malignant and benign group. u200aMalignancy rate of thyroid incidentalomas was significantly higher in the suspicious malignant (88.9u200a%) than in the probably benign group (11.3u200a%) on US (p <u200a0.001). Malignancy rates were high in thyroid nodules with malignancy, suspicious for malignancy, or follicular neoplasm on cytologic results, regardless of US features. However, malignancy rates of thyroid incidentalomas with unsatisfactory or benign results on cytology were higher in the suspicious malignant (75u200a%, 12.5u200a%, respectively) than in the probably benign (0u200a%) group on US.u200annnCONCLUSIONSnThis study demonstrated that the risk of malignancy was high in thyroid incidentalomas on 18F-FDG PET/CT even without suspicious US features. However, there was no malignancy in nodules with no suspicious US features and benign cytology. Based on these results, we concluded that US may not replace FNA in the diagnosis of PET incidentalomas, and that a follow-up may be considered of thyroid incidentalomas with benign cytology and no suspicious US features.

Using 18 F-FDG PET/CT to Detect an Occult Mesenchymal Tumor Causing Oncogenic Osteomalacia

Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by renal phosphate excretion, hypophosphatemia, and osteomalacia. This syndrome is often caused by tumors of mesenchymal origin. Patients with oncogenic osteomalacia have abnormal bone mineralization, resulting in a high frequency of fractures. Tumor resection is the treatment of choice, as it will often correct the metabolic imbalance. Although oncogenic osteomalacia is a potentially curable disease, diagnosis is difficult and often delayed because of the small size and sporadic location of the tumor. Bone scintigraphy and radiography best characterize osteomalacia; magnetic resonance imaging findings are nonspecific. Here, we report a case of oncogenic osteomalacia secondary to a phosphaturic mesenchymal tumor that was successfully detected by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). This case illustrates the advantages of 18F-FDG PET/CT in detecting the occult mesenchymal tumor that causes oncogenic osteomalacia.

Evaluation of Bone Metastasis from Hepatocellular Carcinoma Using 18F-FDG PET/CT and 99mTc-HDP Bone Scintigraphy: Characteristics of Soft Tissue Formation

PurposeBone metastasis from hepatocellular carcinoma (HCC) can present with soft tissue formation, resulting in oncologic emergency. Contrast-enhanced FDG PET/CT and bone scintigraphy were compared to evaluate characteristics of bone metastases with or without soft tissue formation from HCC.MethodsOf 4,151 patients with HCC, 263 patients had bone metastases. Eighty-five patients with bone metastasis from HCC underwent contrast-enhanced FDG PET/CT. Fifty-four of the enrolled subjects had recent 99mTc-HDP bone scintigraphy available for comparison. Metastatic bone lesions were identified with visual inspection on FDG PET/CT, and maximum standardized uptake value (SUVmax) was used for the quantitative analysis. Confirmation of bone metastasis was based on histopathology, combined imaging modalities, or serial follow-up studies.ResultsForty-seven patients (55%) presented with soft tissue formation, while the remaining 38 patients presented without soft tissue formation. Frequent sites of bone metastases from HCC were the spine (39%), pelvis (19%), and rib cage (14%). The soft-tissue-formation group had more frequent bone pain (77 vs. 37%, pu2009<u20090.0001), higher SUVmax (6.02 vs. 3.52, pu2009<u20090.007), and higher incidence of photon defect in bone scintigraphy (75 vs. 0%) compared to the non-soft-tissue-formation group. FDG PET/CT had higher detection rate for bone metastasis than bone scintigraphy both in lesion-based analysis (98 vs. 53%, pu2009=u20090.0015) and in patient-based analysis (100 vs. 80%, pu2009<u20090u2009.001).ConclusionsBone metastasis from HCC showed a high incidence of soft tissue formation requiring emergency treatment. Although the characteristic findings for soft tissue formation such as photon defect in bone scintigraphy are helpful in detection, overall detectability of bone metastasis is higher in FDG PET/CT. Contrast-enhanced PET/CT will be useful in finding and delineating soft-tissue-forming bone metastasis from HCC.

Correlation Between 18F-Fluorodeoxyglucose Uptake and Epidermal Growth Factor Receptor Mutations in Advanced Lung Cancer

PurposeMutations in the epidermal growth factor receptor (EGFR) gene have been identified as potential targets for the treatment and prognostic factors for non-small cell lung cancer (NSCLC). We assessed the correlation between fluorodeoxyglucose (FDG) uptake and EGFR mutations, as well as their prognostic implications.MethodsA total of 163 patients with pathologically confirmed NSCLC were enrolled (99 males and 64 females; median age, 60xa0years). All patients underwent FDG positron emission tomography before treatment, and genetic studies of EGFR mutations were performed. The maximum standardized uptake value (SUVmax) of the primary lung cancer was measured and normalized with regard to liver uptake. The SUVmax between the wild-type and EGFR mutant groups was compared. Survival was evaluated according to SUVmax and EGFR mutation status.ResultsEGFR mutations were found in 57 patients (60.8xa0%). The SUVmax tended to be higher in wild-type than mutant tumors, but was not significantly different (11.1u2009±u20095.7 vs. 9.8u2009±u20094.4, Pu2009=u20090.103). The SUVmax was significantly lower in patients with an exon 19 mutation than in those with either an exon 21 mutation or wild type (Pu2009=u20090.003 and 0.009, respectively). The EGFR mutation showed prolonged overall survival (OS) compared to wild-type tumors (Pu2009=u20090.004). There was no significant difference in survival according to SUVmax. Both OS and progression-free survival of patients with a mutation in exon 19 were significant longer than in patients with wild-type tumors.ConclusionIn patients with NSCLC, a mutation in exon 19 was associated with a lower SUVmax and is a reliable predictor for good survival.

Gemcitabine-Incorporated G-Quadruplex Aptamer for Targeted Drug Delivery into Pancreas Cancer

Gemcitabine has been considered a first-line chemotherapy agent for the treatment of pancreatic cancer. However, the initial response rate of gemcitabine is low and chemoresistance occurs frequently. Aptamers can be effectively internalized into cancer cells via binding to target molecules with high affinity and specificity. In the current study, we constructed an aptamer-based gemcitabine delivery system, APTA-12, and assessed its therapeutic effects on pancreatic cancer cells in vitro and in vivo. APTA-12 was effective in vitro and in vivo in pancreatic cancer cells with high expression of nucleolin. The results of in vitro cytotoxicity assays indicated that APTA-12 inhibited the growth of pancreatic cancer cell lines. In vivo evaluation showed that APTA-12 effectively inhibited the growth of pancreatic cancer in Capan-1 tumor-bearing mice compared to mice that received gemcitabine alone or vehicle. These results suggest that the gemcitabine-incorporated APTA-12 aptamer may be a promising targeted therapeutic strategy for pancreatic cancer.