• Clinical and Experimental Pediatrics
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• v.57 no.6
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• pp.278-286
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• 2014

Purpose: To evaluate the potential utility of $^{123}I$-metaiodobenzylguanine ($^{123}I$-MIBG) scintigraphy and $^{18}F$-fluorodeoxyglucose ($^{18}F$-FDG) positron emission tomography (PET) for the detection of primary and metastatic lesions in pediatric neuroblastoma (NBL) patients, and to determine whether $^{18}F$-FDG PET is as beneficial as $^{123}I$-MIBG imaging. Methods: We selected 8 NBL patients with significant residual mass after operation and who had paired $^{123}I$-MIBG and $^{18}F$-FDG PET images that were obtained during the follow-up. We retrospectively reviewed the clinical charts and the findings of 45 paired scans. Results: Both scans correlated relatively well with the disease status as determined by standard imaging modalities during follow-up; the overall concordance rates were 32/45 (71.1%) for primary tumor sites and 33/45 (73.3%) for bone-bone marrow (BM) metastatic sites. In detecting primary tumor sites, $^{123}I$-MIBG might be superior to $^{18}F$-FDG PET. The sensitivity of $^{123}I$-MIBG and $^{18}F$-FDG PET were 96.7% and 70.9%, respectively, and their specificity were 85.7% and 92.8%, respectively. $^{18}F$-FDG PET failed to detect 9 true NBL lesions in 45 follow-up scans (false negative rate, 29%) with positive $^{123}I$-MIBG. For bone-BM metastatic sites, the sensitivity of $^{123}I$-MIBG and $^{18}F$-FDG PET were 72.7% and 81.8%, respectively, and the specificity were 79.1% and 100%, respectively. $^{123}I$-MIBG scan showed higher false positivity (20.8%) than $^{18}F$-FDG PET (0%). Conclusion: $^{123}I$-MIBG is superior for delineating primary tumor sites, and $^{18}F$-FDG PET could aid in discriminating inconclusive findings on bony metastatic NBL. Both scans can be complementarily used to clearly determine discrepancies or inconclusive findings on primary or bone-BM metastatic NBL during follow-up.

• The Journal of the Korean bone and joint tumor society
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• v.11 no.1
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• pp.32-39
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• 2005

Introduction: Currently, F-18 fluorodeoxyglucose positron emission tomography scans (FDG-PET) has been investigated in soft tissue tumor especially for tumor detection and noninvasive grading. However, the validity and the efficacy of FDG-PET are still unclear in clinical evaluation. The purpose of this study is to determine the efficacy of FDG-PET in compared to conventional diagnostic imaging studies currently used in the soft tissue tumor. Methods: Between March 2001 and March 2002, 29 patients (sixteen males, thirteen females, mean age, 47 years; a range from 4 to 73) diagnosed with soft tissue tumor were evaluated by both conventional diagnostic imaging and FDG-PET. Valid reference test of the local lesion was the histopathologic diagnosis, which was measured in all patients. The suspecting metastasis in the imaging studies was validated by pathology or follow up imaging for at least 6 months. Each imaging diagnosis was made independently. The accuracy of each diagnostic method was evaluated. The incremental cost accuracy ratio was determined in each diagnostic method. Results: For detection of local lesion, sensitivity, specificity, and accuracy for MRI and FDGPET scans were 91%, 57%, 83% and 95%, 43%, 83% respectively. For detection of distant lesion, sensitivity, specificity, accuracy for conventional diagnostic methods and FDG-PET scans were 77%, 89%, 87% and 92%, 94%, 93% respectively. The incremental cost accuracy ratio (ICAR) of FDG-PET for detection of distant lesion was 145,000won/%. According to ICAR for each tumor grade, PET strategy is most cost-effective at high grade tumors. Conclusions: For detection of local lesion such as recurrence or remnant tumor, FDG-PET scan was not more accurate than MRI. However, It was more accurate for detection of metastatic lesion than conventional methods. For detection of high grade tumor, PET was most costeffective than for detection of lower grade tumor.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.535-542
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• 2009

Purpose: This study was performed to know whether [$^{18}F$]Fluorothymidine (FLT) positron emission tomography (PET) can be used to monitor early response to radiotherapy in comparison with [$^{18}F$]Fluorodeoxyglucose (FDG) PET, and to establish the optimal imaging time for prediction of therapy response. Materials and Methods: Two patients with nasopharyngeal cancer underwent serial FLT PET and FDG PET before and during radiotherapy. Three on-treatment FLT and FDG PET scans were performed on 1 week, 2 weeks and 3 weeks (at each time of 10 Gy, 20 Gy and 30 Gy delivered). The peak standardized uptake values ($SUV_{peak}$) of primary tumors were measured on FLT and FDG PET. Then, percent changes of $SUV_{peak}$ after therapy were calculated. Results: In two patients, baseline values of $SUV_{peak}$ on FDT PET were higher than those on FLT PET (FLT vs FDG; 3.7 vs 5.0, and 5.7 vs 15.0). In patient 1, FLT $SUV_{peak}$ showed 78%, 78% and 84% of decrease on 1 week, 2 and 3 weeks after treatment, whereas FDG $SUV_{peak}$ showed 18%, 52% and 66% of decrease, respectively. In patient 2, FLT $SUV_{peak}$ showed 75%, 75% and 68% of decrease, whereas FDG $SUV_{peak}$ showed 51%, 49% and 58% of decrease, respectively. Both patients reached to complete remission after radiotherapy. Conclusion: After radiotherapy, the decrease of FLT tumor uptake preceded the decrease of FDG tumor uptake in patients with nasopharyngeal cancer, and 1 week after therapy may be appropriate time for the assessment of early response. FLT PET might be more useful than FDG PET for monitoring early response to radiotherapy.

• Radiation Oncology Journal
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• v.27 no.3
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• pp.111-119
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• 2009

Purpose: This study aimed at assessing the value of fluorine-18 fluorodeoxyglucose positron emission tomography ($^{18}F$-FDG PET) for predicting the response of locally advanced rectal cancer to neoadjuvant CRT. Materials and Methods: Between August 2006 and January 2008, we prospectively enrolled 20 patients with locally advanced rectal cancer and who were treated with neoadjuvant CRT at the Korea Institute of Radiological and Medical Sciences. The treatment consisted of radiation therapy and chemotherapy, and this was followed by curative resection 6 weeks later. All the patients underwent $^{18}F$-FDG PET/CT both before CRT and 6 weeks after completing CRT. The measurements of the FDG uptake ($SUV_{max}$), the absolute difference (${\Delta}SUV_{max}$) and the percent $SUV_{max}$ difference (response index, $RI_{SUV}$) between the pre- and post-CRT $^{18}F$-FDG PET/CT scans were assessed. The measurements of the metabolic volume, the absolute difference (${\Delta}$metabolic volume) and the percent metabolic volume difference (response index, $RI_{metabolic\;volume}$) were also assessed. Results: Of the 20 patients who underwent surgery, 11 patients (55%) were classified as responders according to Dworak's classification. The post-CRT $SUV_{max}$ was significantly lower than the pre-CRT $SUV_{max}$. However, there were no significant differences in the $SUV_{max}$ and the metabolic volume reduction between the responders and non-responders. We used a minimum $SUV_{max}$ reduction of 67% as the cut-off value for defining a response, with a sensitivity of 45.5%, a specificity of 88.9%, a positive predictive value of 77% and a negative predictive value of 53.8%. Conclusion: Although there were no statistically significant results in this study, other studies have revealed that $^{18}F$-FDG PET/CT has the potential to assess the tumor response to neoadjuvant CRT in patients with locally advanced rectal cancer.

• Journal of Yeungnam Medical Science
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• v.30 no.2
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• pp.116-119
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• 2013

A burnt-out prostate cancer tumor is a very rare clinical entity. The term 'burnt-out' refers to a primary tumor that has spontaneously and nearly completely regressed without treatment. Since metastasis of prostate cancer is usually encountered in the presence of advanced disease, distant metastasis with an undetectable primary tumor is very rare. We report herein a case of a burnt-out prostate cancer tumor that metastasized to the thoracic (T) spine and caused cord compression. A 66-year-old man visited the Emergency Department due to weakness of both legs for the past two days. His blood and urine tests were normal at the time. His spine magnetic resonance imaging (MRI) scans looked like bone metastasis that involved the T-7 vertebral body and a posterior element, and caused spinal cord compression. Other images, including from the brain MRI, neck/chest/abdomino-pelvic computed tomography (CT) scan and 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) and endoscopy, revealed no lesions that suggested malignancy. After total corpectomy T-7 and screw fixation/fusion at T5 to T10, the pathology report revealed a metastatic carcinoma that was strongly positive for prostate-specific antigen (PSA). The serum PSA value was 1.5 ng/mL. The transrectal 12-core prostate biopsy and ultrasonography showed no definitive hypoechoic lesion, but one specimen had slight (only 1%) adenocarcinoma with a Gleason score of 6 (3+3). The final diagnosis was burned-out prostate cancer with an initial normal PSA value. Although metastatic disease with an unknown primary origin was confirmed, a more aggressive approach in seeking the primary origin could provide a more specific treatment strategy and greater clinical benefit to patients.