Eun Seong Lee

Recent Trends in PET Image Interpretations Using Volumetric and Texture-based Quantification Methods in Nuclear Oncology

Image quantification studies in positron emission tomography/computed tomography (PET/CT) are of immense importance in the diagnosis and follow-up of variety of cancers. In this review we have described the current image quantification methodologies employed in 18F-fluorodeoxyglucose (18F-FDG) PET in major oncological conditions with particular emphasis on tumor heterogeneity studies. We have described various quantitative parameters being used in PET image analysis. The main contemporary methodology is to measure tumor metabolic activity; however, analysis of other image-related parameters is also increasing. Primarily, we have identified the existing role of tumor heterogeneity studies in major cancers using 18F-FDG PET. We have also described some newer radiopharmaceuticals other than 18F-FDG being studied/used in the management of these cancers. Tumor heterogeneity studies are being performed in almost all major oncological conditions using 18F-FDG PET. The role of these studies is very promising in the management of these conditions.

New application of dual point 18F-FDG PET/CT in the evaluation of neoadjuvant chemoradiation response of locally advanced rectal cancer.

Purpose FDG PET/CT has been suggested as the most reliable modality to predict pathological tumor responses after neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC). However, several confounding factors including radiation-induced inflammation could not be easily avoided with the commonly used single-point FDG PET/CT. Our aim was to evaluate the accuracy of a dual-point PET/CT protocol in LARC response prediction to CRT. Patients and Methods Sixty-one LARC patients were enrolled and treated with neoadjuvant CRT. PET/CT was performed before and after CRT. Dual-point acquisition was applied to post-CRT PET/CT. Post-CRT SUVmax (postSUV), pre/post-CRT SUVmax change (RI), and dual-point index (DI) of post-CRT PET/CT were compared with the Dworak tumor regression grade (TRG) as a gold standard. Univariate and multivariate analyses, as well as receiver operating characteristic curve analysis, were used to evaluate the predictive ability of demographic, clinical, and metabolic PET parameters. Results Fifteen patients of TRG3-4 were defined as pathological responders, and 46 patients of TRG1-2 were nonresponders. The resulting response index (RI) ranged from −13 to 94.8% (59.1 ± 22.0%), and delay index (DI) ranged from −45.2 to 25.0% (−9.1 ± 12.1%). Univariate analysis resulted in PET parameters (postSUV, RI, and DI) as significant predictors (P = 0.004, P < 0.001, P < 0.0001). According to multivariate analysis, RI and DI remained as significant predictors (P = 0.04 and P = 0.0004). Receiver operating characteristic analysis showed that DI had significantly higher area under the curve compared with RI (0.906 vs 0.696, P = 0.018). Delay index had 86.7% sensitivity, 87.0% specificity, 68.4% positive predictive value, 95.2% negative predictive value, and 86.9% accuracy. Conclusions Dual-point post-CRT PET/CT can predict pathological tumor response better than conventional single time point pre- and post-CRT PET/CT.

Metabolic characteristics of Castleman disease on 18F-FDG PET in relation to clinical implication.

Purpose Castleman disease (CD) is a benign lymphoproliferative disease, which usually shows hypermetabolism on 18F-FDG PET/CT. In this study, we investigated metabolic characteristics of CD in consecutive series of patients and analyzed 18F-FDG uptake with regard to major clinicopathologic factors, to investigate clinical implication of 18F-FDG uptake in CD. Methods Twelve patients (5 men and 7 women; mean age, 52 ± 14 years) with pathologically confirmed CD, who underwent 18F-FDG PET/CT, were retrospectively enrolled, and their images were analyzed. The cases were composed of 10 first diagnosed and 2 relapsed cases. SUVmax was measured for each lesion. Metabolic characteristics were compared according to clinical and pathologic characteristics. Results All the 18F-FDG PET/CT images showed hypermetabolic lesions including small lymph nodes of less than 1 cm. The average SUVmax was 5.8 ± 4.1 with a varying range of 2.4 to 17.1. SUVmax was significantly higher in multicentric than in unicentric disease cases (7.0 ± 4.6 vs 3.3 ± 1.1; P = 0.048) and in the patients with clinical manifestation than the other group (7.1 ± 4.5 and 3.1 ± 0.8, respectively; P = 0.028). Conclusions 18F-FDG PET/CT is an effective diagnostic imaging for diagnosis of CD. Castleman disease shows moderately increased 18F-FDG uptake. In addition, the uptake is well correlated with disease multicentricity and clinical manifestation, suggesting that it would be a significant imaging marker for severity or prognosis of CD.

Intermodality comparison between 3D perfusion CT and 18F-FDG PET/CT imaging for predicting early tumor response in patients with liver metastasis after chemotherapy: Preliminary results of a prospective study

OBJECTIVES To evaluate the feasibility of 3D perfusion CT for predicting early treatment response in patients with liver metastasis from colorectal cancer. METHODS Seventeen patients with colon cancer and liver metastasis were prospectively enroled to undergo perfusion CT and 18F-FDG-PET/CT before and after one-cycle of chemotherapy. Two radiologists and three nuclear medicine physicians measured various perfusion CT and PET/CT parameters, respectively from the largest hepatic metastasis. Baseline values and reduction rates of the parameters were compared between responders and nonresponders. Spearman correlation test was used to correlate perfusion CT and PET/CT parameters, using RECIST criteria as reference standard. RESULTS Nine patients responded to treatment, eight patients were nonresponders. Baseline SUVmean30 on PET/CT, reduction rates of 30% metabolic volume and 30% lesion glycolysis (LG30) on PET/CT and blood flow (BF) and flow extraction product (FEP) on perfusion CT after chemotherapy were significantly different between responders and nonresponders (P=0.008-0.046). Reduction rates of BF (correlation coefficient=0.630) and FEP (correlation coefficient=0.578) significantly correlated with that of LG30 on PET/CT (P<0.05). CONCLUSION CT perfusion parameters including BF and FEP may be used as early predictors of tumor response in patients with liver metastasis from colorectal cancer.

Current Status of Optical Imaging for Evaluating Lymph Nodes and Lymphatic System

Optical imaging techniques use visual and near infrared rays. Despite their considerably poor penetration depth, they are widely used due to their safe and intuitive properties and potential for intraoperative usage. Optical imaging techniques have been actively investigated for clinical imaging of lymph nodes and lymphatic system. This article summarizes a variety of optical tracers and techniques used for lymph node and lymphatic imaging, and reviews their clinical applications. Emerging new optical imaging techniques and their potential are also described.

In Vivo Brain Delivery of v-myc Overproduced Human Neural Stem Cells via the Intranasal Pathway: Tumor Characteristics in the Lung of a Nude Mouse

We aimed to monitor the successful brain delivery of stem cells via the intranasal route and to observe the long-term consequence of the immortalized human neural stem cells in the lungs of a nude mouse model. Stably immortalized HB1.F3 human neural stem cells with firefly luciferase gene (F3-effluc) were intranasally delivered to BALB/c nude mice. Bioluminescence images were serially acquired until 41 days in vivo and at 4 hours and 41 days ex vivo after intranasal delivery. Lungs were evaluated by histopathology. After intranasal delivery of F3-effluc cells, the intense in vivo signals were detected in the nasal area, migrated toward the brain areas at 4 hours (4 of 13, 30.8%), and gradually decreased for 2 days. The brain signals were confirmed by ex vivo imaging (2 of 4, 50%). In the mice with initial lung signals (4 of 9, 44.4%), the lung signals disappeared for 5 days but reappeared 2 weeks later. The intense lung signals were confirmed to originate from the tumors in the lungs formed by F3-effluc cells by ex vivo imaging and histopathology. We propose that intranasal delivery of immortalized stem cells should be monitored for their successful delivery to the brain and their tumorigenicity longitudinally.We aimed to monitor the successful brain delivery of stem cells via the intranasal route and to observe the long-term consequence of the immortalized human neural stem cells in the lungs of a nude mouse model. Stably immortalized HB1.F3 human neural stem cells with firefly luciferase gene (F3-effluc) were intranasally delivered to BALB/c nude mice. Bioluminescence images were serially acquired until 41 days in vivo and at 4 hours and 41 days ex vivo after intranasal delivery. Lungs were evaluated by histopathology. After intranasal delivery of F3-effluc cells, the intense in vivo signals were detected in the nasal area, migrated toward the brain areas at 4 hours (4 of 13, 30.8%), and gradually decreased for 2 days. The brain signals were confirmed by ex vivo imaging (2 of 4, 50%). In the mice with initial lung signals (4 of 9, 44.4%), the lung signals disappeared for 5 days but reappeared 2 weeks later. The intense lung signals were confirmed to originate from the tumors in the lungs formed by F3-effluc cells by ex vivo imaging and histopathology. We propose that intranasal delivery of immortalized stem cells should be monitored for their successful delivery to the brain and their tumorigenicity longitudinally.

Prognostic implication of retrocrural lymph node involvement revealed by 18F-FDG PET/CT in patients with uterine cervical cancer

ObjectivesLymph node involvement in cervical cancer is an indication of poor prognosis and the risk tends to increase according to the level of lymph node involvement. However, the specific prognostic significance of retrocrural lymph node involvement has not been well characterized because of its small size and deep location. The aim of this study was to assess its prognostic value. Patients and methodsA total of 217 patients with newly diagnosed International Federation of Gynecology and Obstetrics (FIGO) stage IA2–IVA cervical cancer were retrospectively enrolled. All the patients had undergone pretreatment 18F-fluorodeoxy-D-glucose (18F-FDG) PET/CT. Of these patients 145 were treated with concurrent chemoradiotherapy, and in this group we assessed the relationship of retrocrural lymph node involvement with the risk of disease progression. ResultsRetrocrural lymph node involvement was seen in 7.4% of patients (16/217). All of them had para-aortic lymph node involvement and 56% of the 16 patients (9/16) had concomitant supraclavicular lymph node involvement. In the patients treated with concurrent chemoradiotherapy it was found that the higher the level of 18F-FDG-positive lymph nodes detected in them, the worse the progression-free survival experienced by them (none vs. pelvic, pelvic vs. para-aortic, para-aortic vs. retrocrural; P<0.05); however, there was no difference in progression outcome between retrocrural and supraclavicular areas (P=NS). On multivariate Cox proportional hazard analysis, the highest level of 18F-FDG PET/CT-positive lymph nodes in the para-aortic [hazard ratio (HR) 6.05, 95% confidence interval (CI) 2.18–16.81], retrocrural (HR 17.05, 95% CI 5.34–54.44), and supraclavicular areas (HR 19.56, 95% CI 7.15–53.54) was a significant prognostic factor. ConclusionThe highest level of lymph node involvement in para-aortic, retrocrural, supraclavicular areas was a significant prognostic factor for progression in uterine cervical cancer patients who were treated with concurrent chemoradiotherapy. Retrocrural lymph node involvement shows a similar outcome with supraclavicular involvement, but leads to a worse outcome in terms of progression compared with para-aortic lymph node involvement.

Comparison of [18F]-FDG and [18F]-NaF Positron Emission Tomography on Culprit Carotid Atherosclerosis: A Prospective Study

The application of positron emission tomography (PET) with different radioisotopes in atherosclerosis can detect various pathological cascades within atheroma [(1)][1]. The 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) ligand was the first radioisotope introduced in atherosclerosis study that measures

Unexpected Second Primary Malignancies Detected by F-18 FDG PET/CT During Follow-up for Primary Malignancy: Two Case Reports

As the survival rate of cancer patients has increased over the last few decades, the risk of cancer survivors developing second primary malignancies has gained attention. We report two rare cases of second primary hematologic malignancy detected by 18F-fluorodeoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) during follow-up for primary solid malignancies. Acute lymphoblastic leukemia developed in a breast cancer patient and non-Hodgkin lymphoma in an anal cancer patient. F-18 FDG PET/CT findings led to the diagnosis of unexpected second primary hematologic malignancy in cancer survivors in these two cases.

A Case of Meigs' Syndrome: The (18)F-FDG PET/CT Findings.

The findings of an ovarian mass with marked ascites and pleural effusion are highly suggestive of malignancy, especially in a postmenopausal female with an elevated level of CA-125. However, benign conditions such as Meigs’ syndrome should be considered in the differential diagnosis if the primary mass shows benign features. 18F-FDG is known to be useful to differentiate between malignant and benign diseases, and this utility is also promising in the case of ovarian tumor. We present here a case of Meigs’ syndrome that was evaluated by 18F-FDG PET/CT, and this helped the preoperative diagnosis be made. 18F-FDG PET/CT is a promising modality to diagnose the pathological character of an ovarian tumor preoperatively, which can lead to a proper therapeutic plan.