Cortical Thickness and Brain Glucose Metabolism in Healthy Aging

Background@#and PurposeWe aimed to determine the effect of demographic factors on cortical thickness and brain glucose metabolism in healthy aging subjects. @*Methods@#The following tests were performed on 71 subjects with normal cognition: neurological examination, 3-tesla magnetic resonance imaging, 18F-fluorodeoxyglucose positron-emission tomography, and neuropsychological tests. Cortical thickness and brain metabolism were measured using vertex- and voxelwise analyses, respectively. General linear models (GLMs) were used to determine the effects of age, sex, and education on cortical thickness and brain glucose metabolism. The effects of mean lobar cortical thickness and mean lobar metabolism on neuropsychological test scores were evaluated using GLMs after controlling for age, sex, and education. The intracranial volume (ICV) was further included as a predictor or covariate for the cortical thickness analyses. @*Results@#Age was negatively correlated with the mean cortical thickness in all lobes (frontal and parietal lobes, p=0.001; temporal and occipital lobes, p<0.001) and with the mean temporal metabolism (p=0.005). Education was not associated with cortical thickness or brain metabolism in any lobe. Male subjects had a lower mean parietal metabolism than did female subjects (p<0.001), while their mean cortical thicknesses were comparable. ICV was positively correlated with mean cortical thickness in the frontal (p=0.016), temporal (p=0.009), and occipital (p=0.007) lobes. The mean lobar cortical thickness was not associated with cognition scores, while the mean temporal metabolism was positively correlated with verbal memory test scores. @*Conclusions@#Age and sex affect cortical thickness and brain glucose metabolism in different ways. Demographic factors must therefore be considered in analyses of cortical thickness and brain metabolism.

Relationship between Hearing Loss and Dementia Differs According to the Underlying Mechanism

Background@#and Purpose The associations between hearing loss (HL) and the mechanisms underlying cognitive impairment (CI) remain unclear. We evaluated the effects of clinical factors, vascular magnetic resonance imaging (MRI) markers, and CI mechanisms on HL. @*Methods@#In total, 112 patients with CI (59% demented) and subjective HL prospectively underwent MRI, amyloid positron-emission tomography (PET), hearing evaluations, and neuropsychological tests including a language comprehension test. Patients were categorized into pure-Alzheimer’s disease-related CI (ADCI), pure-Lewy-body disease-related CI (LBCI), mixed-ADCI/LBCI, and non-ADCI/LBCI groups based on clinical features and PET biomarkers. @*Results@#The risk of peripheral HL [defined as a pure-tone average (PTA) threshold >40 dB] was higher in the pure-LBCI group than in the pure-ADCI and mixed-ADCI/LBCI groups, and lower in the presence of ADCI. The non-ADCI/LBCI group had the most-severe vascular MRI markers and showed a higher risk of peripheral HL than did the pure-ADCI and mixed-ADCI/LBCI groups. While the pure-LBCI group had a higher risk of comprehension dysfunction than the pure-ADCI group regardless of the PTA and the score on the Korean version of the Mini Mental State Examination (K-MMSE), those in the pure-LBCI group even with a better K-MMSE score had a risk of comprehension dysfunction comparable to that in the mixed-ADCI/LBCI group due to a worse PTA. @*Conclusions@#Peripheral HL could be associated with the absence of significant β-amyloid deposition in patients with CI and characteristic of the pure-LBCI and non-ADCI/LBCI groups.

Relationship between Hearing Loss and Dementia Differs According to the Underlying Mechanism

Background@#and Purpose The associations between hearing loss (HL) and the mechanisms underlying cognitive impairment (CI) remain unclear. We evaluated the effects of clinical factors, vascular magnetic resonance imaging (MRI) markers, and CI mechanisms on HL. @*Methods@#In total, 112 patients with CI (59% demented) and subjective HL prospectively underwent MRI, amyloid positron-emission tomography (PET), hearing evaluations, and neuropsychological tests including a language comprehension test. Patients were categorized into pure-Alzheimer’s disease-related CI (ADCI), pure-Lewy-body disease-related CI (LBCI), mixed-ADCI/LBCI, and non-ADCI/LBCI groups based on clinical features and PET biomarkers. @*Results@#The risk of peripheral HL [defined as a pure-tone average (PTA) threshold >40 dB] was higher in the pure-LBCI group than in the pure-ADCI and mixed-ADCI/LBCI groups, and lower in the presence of ADCI. The non-ADCI/LBCI group had the most-severe vascular MRI markers and showed a higher risk of peripheral HL than did the pure-ADCI and mixed-ADCI/LBCI groups. While the pure-LBCI group had a higher risk of comprehension dysfunction than the pure-ADCI group regardless of the PTA and the score on the Korean version of the Mini Mental State Examination (K-MMSE), those in the pure-LBCI group even with a better K-MMSE score had a risk of comprehension dysfunction comparable to that in the mixed-ADCI/LBCI group due to a worse PTA. @*Conclusions@#Peripheral HL could be associated with the absence of significant β-amyloid deposition in patients with CI and characteristic of the pure-LBCI and non-ADCI/LBCI groups.

Choroid Plexus as the Best Reference Region for Standardized Uptake Value Analysis on C11-Acetate PET/CT for Grading and Predicting Prognosis in Patients with Cerebral Gliomas / 대한핵의학회잡지

Purpose@#We aimed to compare different reference regions and select one with the most clinical relevance on C11-acetate (ACE) positron emission tomography/computed tomography (PET/CT) in patients with cerebral glioma. @*Methods@#We retrospectively reviewed 51 patients with cerebral glioma who underwent baseline ACE PET/CT at diagnosis.Other than the standardized uptake value (SUV) of the primary tumor, SUVs of the reference regions including the normal gray matter, white matter, choroid plexus, and cerebellum were measured. Then, the SUV ratio (SUVR = tumor SUV max /reference region SUV mean ) was calculated. The effect of patient age on the SUV mean of each reference was examined and the SUVRs of each reference region were compared between grades. age, sex, tumor size, histological grades, SUVR , and the presence of isocitrate dehydrogenase (IDH) mutation were included for survival analyses. @*Results@#Except for the cerebellum showing a mild negative correlation, we found no correlations between age and SUV mean using the gray matter, white matter, and choroid plexus (r = − 0.280, P < = 0.047). Only the SUVR -choroid plexus was able to differentiate between the WHO grades (Grade II vs. III, P < = 0.035; grade III vs. IV, P < < 0.001; grade II vs. IV, P < 0.001). Multivariate Cox proportional hazards models found that the SUVR-choroid plexus and IDH mutation were statistically significant for predicting OS. @*Conclusion@#Of the different reference regions used for grading cerebral gliomas, the choroid plexus was found to be the most optimal.In addition, the SUV ratio is useful to predict the overall survival in the model with the choroid plexus as a reference region.

Synergistic Antitumor Effects of Combined Treatment with HSP90 Inhibitor and PI3K/mTOR Dual Inhibitor in Cisplatin-Resistant Human Bladder Cancer Cells

Purpose@#The current study aimed to investigate the synergistic antitumor effect of combined treatment with 17-DMAG (HSP90 inhibitor) and NVP-BEZ235 (PI3K/mTOR dual inhibitor) on cisplatin-resistant human bladder cancer cells. @*Materials and Methods@#Human bladder cancer cells exhibiting cisplatin resistance (T24R2) were exposed to escalating doses of 17-DMAG (2.5–20 nM) with or without NVP-BEZ236 (0.5–4 μM) in combination with cisplatin. Antitumor effects were assessed by CCK-8 analysis. Based on the dose-response study, synergistic interactions between the two regimens were evaluated using clonogenic assay and combination index values. Flow cytometry and Western blot were conducted to analyze mechanisms of synergism. @*Results@#Dose- and time-dependent antitumor effects for 17-DMAG were observed in both cisplatin-sensitive (T24) and cisplatin- resistant cells (T24R2). The antitumor effect of NVP-BEZ235, however, was found to be self-limiting. The combination of 17- DMAG and NVP-BEZ235 in a 1:200 fixed ratio showed a significant antitumor effect in cisplatin-resistant bladder cancer cells over a wide dose range, and clonogenic assay showed compatible results with synergy tests. Three-dimensional analysis revealed strong synergy between the two drugs with a synergy volume of 201.84 μM/mL2%. The combination therapy resulted in G1-phase cell cycle arrest and caspase-dependent apoptosis confirmed by the Western blot. @*Conclusion@#HSP90 inhibitor monotherapy and in combination with the PI3K/mTOR survival pathway inhibitor NVP-BEZ235 shows a synergistic antitumor effect in cisplatin-resistant bladder cancers, eliciting cell cycle arrest at the G1 phase and induction of caspase-dependent apoptotic pathway.

Preoperative Metabolic Tumor Volume(2.5) Associated with Early Systemic Metastasis in Resected Pancreatic Cancer: A Transcriptome-Wide Analysis

BACKGROUND/AIMS: ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET) reflects biological aggressiveness and predicts prognoses in various tumors. Evaluating the oncologic significance of the preoperative metabolic phenotype might be necessary for planning the surgical strategy in resectable pancreatic cancers. METHODS: From January 2010 to December 2015, a total of 93 patients with pathologic T3 (pT3) pancreatic cancer were included in this study. Clinicopathological parameters and PET parameters were evaluated, and transcriptome-wide analysis was performed to identify the oncologic impact and molecular landscape of the metabolic phenotype of resectable pancreatic cancers. RESULTS: Preoperative metabolic tumor volume (MTV)(2.5) was significantly higher in the pN1 group compared to the pN0 group (11.1±11.2 vs 6.5±7.8, p=0.031). Higher MTV(2.5) values (MTV(2.5) ≥4.5) were associated with multiple lymph node metastasis (p=0.003), and the lymph node ratio was also significantly higher in resected pT3 pancreatic cancer with MTV(2.5) ≥4.5 compared to those with MTV(2.5) <4.5 (0.12±0.13 vs 0.05±0.08, p=0.001). Disease-specific survival of patients with MTV(2.5) <4.5 was better than that of patients with MTV(2.5) ≥4.5 (mean, 28.8 months; 95% confidence interval [CI], 40.1 to 57.0 vs mean, 32.6 months; 95% CI, 25.5 to 39.7; p=0.026). Patients with MTV(2.5) ≥4.5 who received postoperative adjuvant chemotherapy showed better survival outcomes than patients with MTV(2.5) ≥4.5 who did not receive adjuvant treatment in resected pT3 pancreatic cancers (p<0.001). Transcriptome-wide analysis revealed that tumors with MTV(2.5) ≥4.5 demonstrated significantly different expression of cancer-related genes reflecting aggressive tumor biology. CONCLUSIONS: Resectable pancreatic cancer with high MTV(2.5) is not only associated with lymph node metastasis but also early systemic metastasis. The molecular background of resectable pancreatic cancer with high MTV(2.5) may be associated with aggressive biologic behavior, which might need to be considered when managing resectable pancreatic cancers. Further study is mandatory.

Cancer Metabolism as a Mechanism of Treatment Resistance and Potential Therapeutic Target in Hepatocellular Carcinoma

Various molecular targeted therapies and diagnostic modalities have been developed for the treatment of hepatocellular carcinoma (HCC); however, HCC still remains a difficult malignancy to cure. Recently, the focus has shifted to cancer metabolism for the diagnosis and treatment of various cancers, including HCC. In addition to conventional diagnostics, the measurement of enhanced tumor cell metabolism using F-18 fluorodeoxyglucose (18F-FDG) for increased glycolysis or C-11 acetate for fatty acid synthesis by positron emission tomography/computed tomography (PET/CT) is well established for clinical management of HCC. Unlike tumors displaying the Warburg effect, HCCs vary substantially in terms of 18F-FDG uptake, which considerably reduces the sensitivity for tumor detection. Accordingly, C-11 acetate has been proposed as a complementary radiotracer for detecting tumors that are not identified by 18F-FDG. In addition to HCC diagnosis, since the degree of 18F-FDG uptake converted to standardized uptake value (SUV) correlates well with tumor aggressiveness, 18F-FDG PET/CT scans can predict patient outcomes such as treatment response and survival with an inverse relationship between SUV and survival. The loss of tumor suppressor genes or activation of oncogenes plays an important role in promoting HCC development, and might be involved in the “metabolic reprogramming” of cancer cells. Mutations in various genes such as TERT, CTNNB1, TP53, and Axin1 are responsible for the development of HCC. Some microRNAs (miRNAs) involved in cancer metabolism are deregulated in HCC, indicating that the modulation of genes/miRNAs might affect HCC growth or metastasis. In this review, we will discuss cancer metabolism as a mechanism for treatment resistance, as well as an attractive potential therapeutic target in HCC.

Evaluation of ¹⁸F-FDG PET/CT Parameters for Detection of Lymph Node Metastasis in Cutaneous Melanoma / 대한핵의학회잡지

PURPOSE: The purpose of this study was to investigate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) parameters in the detection of regional lymph node (LN) metastasis in patients with cutaneous melanoma.METHODS: We evaluated patients with cutaneous melanoma who underwent FDG PET/CT for initial staging or recurrence evaluation. A total of 103 patients were enrolled, and 165 LNs were evaluated. LNs that were confirmed pathologically or by follow-up imaging were included in this study. PET parameters, including maximum standardized uptake value (SUVmax), total lesion glycolysis and tumour-to-liver ratio, were used to determine the presence of metastases, and the results were compared with CT-determined LN metastasis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off values of the FDG PET parameters.RESULTS: A total of 93 LNs were malignant, and 84 LNs were smaller than 10 mm. In all 165 LNs, an SUVmax of >2.51 showed a sensitivity of 73.1%, a specificity of 88.9%, and an accuracy of 80.0% in detecting metastatic LNs. CT showed a higher specificity (87.3%) and lower accuracy (65.5%). For non-enlarged regional LNs ( < 10 mm), an SUVmax cut-off value of 1.4 showed the highest negative predictive value (81.3%). For enlarged LNs (≥10 mm), an SUVmax cut-off value of 2.4 showed the highest sensitivity (90.7%) and accuracy (88.9%) in detecting metastatic LNs.CONCLUSIONS: In patients with cutaneous melanoma, an SUVmax of >2.4 showed a high sensitivity (91%) and accuracy (89%) in detecting metastasis in LNs ≥1 cm, and LNs < 1 cm with an SUVmax < 1.4 were likely to be benign.

Evaluation of ¹⁸F-FDG PET/CT Parameters for Detection of Lymph Node Metastasis in Cutaneous Melanoma / 대한핵의학회잡지

PURPOSE@#The purpose of this study was to investigate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) parameters in the detection of regional lymph node (LN) metastasis in patients with cutaneous melanoma.@*METHODS@#We evaluated patients with cutaneous melanoma who underwent FDG PET/CT for initial staging or recurrence evaluation. A total of 103 patients were enrolled, and 165 LNs were evaluated. LNs that were confirmed pathologically or by follow-up imaging were included in this study. PET parameters, including maximum standardized uptake value (SUVmax), total lesion glycolysis and tumour-to-liver ratio, were used to determine the presence of metastases, and the results were compared with CT-determined LN metastasis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off values of the FDG PET parameters.@*RESULTS@#A total of 93 LNs were malignant, and 84 LNs were smaller than 10 mm. In all 165 LNs, an SUVmax of >2.51 showed a sensitivity of 73.1%, a specificity of 88.9%, and an accuracy of 80.0% in detecting metastatic LNs. CT showed a higher specificity (87.3%) and lower accuracy (65.5%). For non-enlarged regional LNs ( 2.4 showed a high sensitivity (91%) and accuracy (89%) in detecting metastasis in LNs ≥1 cm, and LNs < 1 cm with an SUVmax < 1.4 were likely to be benign.

Usefulness of SPECT/CT in Parathyroid Lesion Detection in Patients with Thyroid Parenchymal (99m)Tc-Sestamibi Retention / 대한핵의학회잡지

PURPOSE: Parathyroid adenoma detection with dual-phase (99m)Tc-sestamibi (MIBI) scintigraphy depends on differential MIBI washout from thyroid. However, autoimmune thyroid disease (AITD) may cause MIBI to be retained in the thyroid gland and reduce parathyroid detection.We evaluated the impact of AITD on MIBI thyroid retention and additional benefit of SPECT/CT in these patients.METHODS: Dual phase planar MIBI and SPECT/CT was performed on 82 patients. SPECT/CTwas performed immediatelyafter delayed planar scan. Thyroid density (Hounsfield unit, CT-HU) and size were measured on CT component of SPECT/CT. MIBI uptake in early scans and retention in delayed scans were visually graded and correlated with clinical factors and CT findings. Finally, planar and SPECT/CT findings were compared for parathyroid lesion visualization according to thyroid MIBI retention.RESULTS: In early scan, multivariate analysis showed only thyroid size predicted early uptake. In delayed scan, multivariate analysis showed higher visual grade in early scan, lower CTHU or AITD were significant predictors for delayed thyroid parenchymal retention. Overall, ten more parathyroid lesions were visualized on SPECT/CT compared to planar scans (57 vs. 47, p = 0.002). SPECT/CT was especially more useful in patients with thyroidal MIBI retention, as eight out of the ten additional lesions detected were found in patients with thyroid MIBI retention.CONCLUSION: AITD is an important factor for MIBI thyroid parenchymal retention on delayed scans, and may impede parathyroid lesion detection. Patients with MIBI retention in the thyroid parenchyma on delayed scans are likely to benefit from an additional SPECT/CT.

The Clinical Usefulness of ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography (PET) to Predict Oncologic Outcomes and PET-Based Radiotherapeutic Considerations in Locally Advanced Nasopharyngeal Carcinoma / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: We investigated ¹⁸F-fluorodeoxyglucose positron emission tomography (PET)-derived parameters as prognostic indices for disease progression and survival in locally advanced nasopharyngeal carcinoma (NPC) and the effect of high-dose radiotherapy for a subpopulation with PET-based poor prognoses. MATERIALS AND METHODS: Ninety-seven stage III and Iva-b NPC patients who underwent definitive treatment and PET were reviewed. For each primary, nodal, and whole tumor, maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis (TLG) were evaluated. RESULTS: Based on the C-index (0.666) and incremental area under the curve (0.669), the whole tumor TLGwas the most useful predictorfor progression-free survival (PFS); thewhole tumor TLG cut-off value showing the best predictive performance was 322.7. In multivariate analysis, whole tumor TLG was a significant prognostic factor for PFS (hazard ratio [HR], 0.3; 95% confidence interval [CI], 0.14 to 0.65; p=0.002) and OS (HR, 0.29; 95% CI, 0.11 to 0.79; p=0.02). Patients with low whole tumor TLG showed the higher 5-year PFS in the subgroup for only patients receiving intensity modulated radiotherapy (77.4% vs. 53.0%, p=0.01). In the subgroup of patients with high whole tumor TLG, patients receiving an EQD₂≥ 70 Gy showed significantly greater complete remission rates (71.4% vs. 33.3%, p=0.03) and higher 5-year OS (74.7% vs. 19.6%, p=0.02). CONCLUSION: Our findings demonstrated that whole tumor TLG could be an independent prognostic factor and high-dose radiotherapy could improve outcomes for NPC showing high whole tumor TLG.

18F-FDG/PET May Help to Identify a Subgroup of Patients with T1-T2 Breast Cancer and 1-3 Positive Lymph Nodes Who Are at a High Risk of Recurrence after Mastectomy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study is to assess the utility of positron emission tomography (PET) for predicting recurrence among patients with T1-T2/N1 breast cancer who were treated with mastectomy. MATERIALS AND METHODS: Of 712 consecutive patients with T1-T2/N1 breast cancer treated during 2003-2012, 109 had undergone preoperative 18F-fluorodeoxyglucose/PET and were included. Metabolic (maximum standardized uptake value [SUVmax]), volumetric (metabolic tumor volume [MTV]), and combined (total lesion glycolysis [TLG]) indices were measured. The resulting values were analyzed and compared with clinical outcome. RESULTS: At the median follow-up of 46.7 months, the 3-year relapse-free survival (RFS) rate was 95.2%. SUVmax (area under curve, 0.824) was more useful than MTV or TLG as a means of identifying patients at high risk for any recurrence. In multivariate analysis, SUVmax remained an independent risk factor for RFS (p=0.006). Using the method of Contal and O'Quigley, a SUVmax threshold of 5.36 showed the best predictive performance. The PET-based high-risk group (≥ 5.36 in either breast or nodes) had more T1c-T2, high-grade, hormone-receptor negative, and invasive ductal carcinoma tumors than the low-risk group (< 5.36 in both breast and nodes). The prognosis was much worse when high SUVmax (≥ 5.36) was detected in nodes (p < 0.001). In the no-radiotherapy cohort, the PET-based high-risk group had increased risk of locoregional recurrence when compared to the low-risk group (p=0.037). CONCLUSION: High SUVmax on preoperative PET showed association with elevated risk of locoregional recurrence and any recurrence. Pre-treatment PET may improve assessments of recurrence risk and clarify indications for post-mastectomy radiotherapy in this subset of patients.

Imaging of Gastric Cancer Metabolism Using 18 F-FDG PET/CT

Aerobic glycolysis has been the most important hypothesis in cancer metabolism. It seems to be related to increased bioenergetic and biosynthetic needs in rapidly proliferating cancer cells. To this end, F-18 fluorodeoxyglucose (FDG), a glucose analog, became widely popular for the detection of malignancies combined with positron emission tomography/computed tomography (PET/CT). Although the potential roles of FDG PET/CT in primary tumor detection are not fully established, it seems to have a limited sensitivity in detecting early gastric cancer and mainly signet ring or non-solid types of advanced gastric cancer. In evaluating lymph node metastases, the location of lymph nodes and the degree of FDG uptake in primary tumors appear to be important factors affecting the diagnostic accuracy of PET/CT. In spite of the limited sensitivity, the high specificity of PET/CT for lymph node metastases may play an important role in changing the extent of lymphadenectomy or reducing futile laparotomies. For peritoneal metastases, PET/CT seems to have a poorer sensitivity but a better specificity than CT. The roles of PET/CT in the evaluation of other distant metastases are yet to be known. Studies including primary tumors with low FDG uptake or peritoneal recurrence seem suffer from poorer diagnostic performance for the detection of recurrent gastric cancer. There are only a few reports using FDG PET/CT to predict response to neoadjuvant or adjuvant chemotherapy. A complete metabolic response seems to be predictive of more favorable prognosis.

Prognostic Value of 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients with Resectable Pancreatic Cancer

PURPOSE: We evaluated the prognostic value of 18F-2-fluoro-2-deoxyglucose positron emission tomography (FDG PET) in patients with resectable pancreatic cancer. MATERIALS AND METHODS: We retrospectively reviewed the medical records of pancreatic cancer patients who underwent curative resection, which included 64 consecutive patients who had preoperative FDG PET scans. For statistical analysis, the maximal standardized uptake value (SUVmax) of primary pancreatic cancer was measured. Survival time was estimated by the Kaplan-Meier method, and Cox's proportional hazard model was used to determine whether SUVmax added new predictive information concerning survival together with known prognostic factors. p3.5) showed significantly shorter OS and DFS than the low SUVmax group. Multivariate analysis of OS and DFS showed that both high SUVmax and poor tumor differentiation were independent poor prognostic factors. CONCLUSION: Our study showed that degree of FDG uptake was an independent prognostic factor in pancreatic cancer patients who underwent curative resection.

Role of 18F-FDG PET Scans in Patients with Helicobacter pylori-Infected Gastric Low-Grade MALT Lymphoma

BACKGROUND/AIMS: Endoscopic ultrasound (EUS) plays a crucial role in the assessment and treatment of low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma; however, interobserver variation, inadequate accuracy in judging the depth of tumor invasion, and histological heterogeneity of the tumor can limit its role. Thus, we have assessed the role of 18F-FDG PET scans in the management of Helicobacter pylori-infected gastric MALT lymphoma. METHODS: Eighteen patients with H. pylori-infected low-grade gastric MALT lymphoma underwent an 18F-FDG PET scan prior to receiving H. pylori eradication therapy. We analyzed these patients' clinicopathologic data and measured the baseline and change in the metabolic activity of the tumor using standardized uptake values (SUVs). RESULTS: Two patients failed to achieve complete remission of the low-grade gastric MALT lymphoma after successful H. pylori eradication. The baseline SUVs were significantly higher in these patients compared to successfully treated patients, 13.35+/-0.07 vs 2.98+/-0.93, respectively (n=2 vs n=16, p<0.001). The reduction in the SUV was significantly greater in the complete remission patients compared to treatment failure patients (p=0.018). CONCLUSIONS: A high SUV at baseline 18F-FDG PET and a lower reduction in the SUV within 3 months after eradication therapy are associated with treatment failure in H. pylori-positive low-grade gastric MALT lymphoma patients undergoing eradication treatment.

The value of Dedicated Tc-99m MIBI Scintimammography in the Evaluation of Patients with Palpable Breast Lesions in Comparison with Mammography: Preliminary Result / 핵의학분자영상

PURPOSE: There are few studies evaluating the usefulness of dedicated high-resolution scintimammography and no studies using delayed washout with this dedicated high resolution scintimammography for the evaluation of breast lesions. We underwent this study to evaluate the clinical usefulness of Tc-99m MIBI in evaluating patients with palpable breast lesions using dedicated high-resolution scintimammography. MATERIALS AND METHODS: This study included 19 patients with 23 palpable breast lesions who underwent mammography. Tc-99m MIBI was taken to further characterize these lesions. Scintimammography images were acquired with standard craniocaudal and mediolateral oblique views and delayed images were additionally taken. Final conclusions were based on histopathology, either by biopsy or mastectomy results. RESULTS: Eighteen lesions were malignant and five were benign. Mammography was indeterminate for thirteen lesions, nine of those were malignant. Mammography also categorized one lesion as benign in a dense breast, but scintimammography and pathology results showed malignancy. Of the five benign lesions, two were visible on scintimammography, but delayed images showed washout. CONCLUSION: Based on our preliminary results, dedicated high resolution scintimammography seems to be very useful in characterizing palpable lesions that were indeterminate or negative on mammography.

Radiation Safety Issues Related to Sentinel Lymph Node Biopsy using Radioactive Colloid: Commentary on "Exposure of Surgical Staff to Radiation" / 한국유방암학회지

No abstract available.

Imaging of Viral Thymidine Kinase Gene Expression by Replicating Oncolytic Adenovirus and Prediction of Therapeutic Efficacy

PURPOSE: We have used a genetically attenuated adenoviral vector which expresses HSVtk to assess the possible additive role of suicidal gene therapy for enhanced oncolytic effect of the virus. Expression of TK was measured using a radiotracer-based molecular counting and imaging system. MATERIALS AND METHODS: Replication-competent recombinant adenoviral vector (Ad-deltaE1B19/55) was used in this study, whereas replication-incompetent adenovirus (Ad-deltaE1A) was generated as a control. Both Ad-deltaE1B19/55-TK and Ad-deltaE1A-TK comprise the HSVtk gene inserted into the E3 region of the viruses. YCC-2 cells were infected with the viruses and incubated with 2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl-5-iodouracil (I-131 FIAU) to measure amount of radioactivity. The cytotoxicity of the viruses was determined, and gamma ray imaging of HSVtk gene was performed. MTT assay was also performed after GCV treatment. RESULTS: On gamma counter-analyses, counts/minute (cpm)/microgram of protein showed MOIs dependency with deltaE1B19/55-TK infection. On MTT assay, Ad-deltaE1B19/55-TK led to more efficient cell killing than Ad-deltaE1A-TK. On plate imaging by gamma camera, both Ad-deltaE1B19/55-TK and Ad-deltaE1A-TK infected cells showed increased I-131 FIAU uptake in a MOI dependent pattern, and with GCV treatment, cell viability of deltaE1B19/55-TK infection was remarkably reduced compared to that of Ad-deltaE1A-TK infection. CONCLUSION: Replicating Ad-deltaE1B19/55-TK showed more efficient TK expression even in the presence of higher-cancer cell killing effects compared to non-replicating Ad-deltaE1A-TK. Therefore, GCV treatment still possessed an additive role to oncolytic effect of Ad-deltaE1B19/55-TK. The expression of TK by oncolytic viruses could rapidly be screened using a radiotracer-based counting and imaging technique.

FDG Uptake in the Pathologically Proven Papillary Thyroid Cancer / 핵의학분자영상

PURPOSE: Metastatic thyroid cancers with I-131 uptake have been known to show no increase of FDG uptake whereas those without I-131 uptake tend to demonstrate increased uptake on PET. In this study, we evaluated the degree of FDG uptake in primary thyroid cancers of papillary histology before surgery. MATERIAL AND METHODS: Forty FDG PET studies were performed on the patients who had papillary cancer proven by fine needle aspiration. The degree of FDG uptake was visually categorized as positive or negative (positive if the tumor showed discernible FDG; negative if the tumor didn't) and the peak standard uptake value (peak SUV) of the papillary thyroid cancer (PTC) were compared with the size of PTC. RESULTS: The mean size of 26 PTC with positive FDG uptake was 1.9+/-1.4 cm(0.5~5 cm). In 13 PTC with negative FDG uptake, the mean size of those was 0.5+/-0.2 cm (0.2~0.9 cm). All PTC larger than 1cm (2.5+/-1.4 cm, 1~5 cm) have positive FDG uptake (peak SUV=6.4+/-5.7, 1.7~22.7). Among the micropapillary thyroid cancer (microPTC; PTC smaller than 1cm), 8 microPTC show positive FDG uptake(peak SUV=2.9+/-1.3, 1.7~5.5), while 13 microPTC show negative finding(peak SUV=1.3+/-0.2, 1.1~1.7). The size of microPTC with positive FDG uptake is significantly larger than that of microPTC with negative FDG uptake (0.7+/-0.1 cm vs 0.4+/-0.2 cm, p=0.01). CONCLUSION: All PTCs larger than 1cm show positive FDG uptake in our study. In other words, thyroid lesions larger than 1cm with negative FDG uptake are unlikely to be PTC. So far, only poorly differentiated thyroid cancers are known to show increased FDG uptake. Our results seem to be contradictory to what is known in the literature. Further study is needed to understand better the significance of increased FDG uptake in PTC in relation to expression of NIS and GLUT.

The role of Positron Emission Tomography in hepatobiliary cancers / 한양의대학술지

Imaging approach for early diagnosis, accurate staging, and the evaluation of treatment response has been consisted of anatomical and functional imaging methods. The anatomical image usually depends on high spatial resolution to distinguish morphological difference from normal anatomy, but altered anatomy is not a specific finding for malignancy. Moreover, it frequently needs other imaging modalities for systemic evaluation of disease. The functional image has been used for research and clinical purpose to overcome these shortcomings of the anatomical image, and the importance of functional evaluation of tumors is widely accepted by the introduction of Positron Emission Tomography (PET). Most of the PET systems at present are supplied as PET/CT combining functional and anatomical images, altogether. Especially for hepatobiliary tumors, showing a low sensitivity by PET alone, PET/CT will play an important role in determining TNM stage, deciding treatment modality, and evaluating treatment response. In addition, PET/CT as the most advanced molecular image technique has further growing potentials such as the development of a faster PET system, various new PET tracers, etc, which will contribute to improving patient survival and the quality of life.