Change of Therapeutic Response Classification According to Recombinant Human Thyrotropin‑Stimulated Thyroglobulin Measured at Different Time Points in Papillary Thyroid Carcinoma / 대한핵의학회잡지

Purpose@#We investigated whether response classification after total thyroidectomy and radioactive iodine (RAI) therapy could be affected by serum levels of recombinant human thyrotropin (rhTSH)-stimulated thyroglobulin (Tg) measured at different time points in a follow-up of patients with papillary thyroid carcinoma (PTC). @*Methods@#A total of 147 PTC patients underwent serum Tg measurement for response assessment 6 to 24 months after the first RAI therapy. Serum Tg levels were measured at 24 h (D1Tg) and 48–72 h (D2-3Tg) after the 2nd injection of rhTSH. Responses were classified into three categories based on serum Tg corresponding to the excellent response (ER-Tg), indeterminate response (IR-Tg), and biochemical incomplete response (BIR-Tg). The distribution pattern of response classification based on serum Tg at different time points (D1Tg vs. D2-3Tg) was compared. @*Results@#Serum D2-3Tg level was higher than D1Tg level (0.339 ng/mL vs. 0.239 ng/mL, P < 0.001). The distribution of response categories was not significantly different between D1Tg-based and D2-3Tg-based classification. However, 8 of 103 (7.8%) patients and 3 of 40 (7.5%) patients initially categorized as ER-Tg and IR-Tg based on D1Tg, respectively, were reclassified to IR-Tg and BIR-Tg based on D2-3Tg, respectively. The optimal cutoff values of D1Tg for the change of response categories were 0.557 ng/mL (from ER-Tg to IR-Tg) and 6.845 ng/mL (from IR-Tg to BIR-Tg). @*Conclusion@#D1Tg measurement was sufficient to assess the therapeutic response in most patients with low level of D1Tg. Nevertheless, D2-3Tg measurement was still necessary in the patients with D1Tg higher than a certain level as response classification based on D2-3Tg could change.

Clinical Impact of F-18 FDG PET-CT on Biopsy Site Selection in Patients with Suspected Bone Metastasis of Unknown Primary Site / 대한핵의학회잡지

Purpose@#We investigated the clinical role of F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography(PET-CT) in the identification of the primary site and the selection of the optimal biopsy site in patients with suspectedbone metastasis of unknown primary site. @*Methods@#The patients with suspected bone metastasis who underwent PET-CT for evaluation of primary site were enrolled inthis study. The primary sites were identified by the histopathologic or imaging studies and were classified according to the FDGuptake positivity of the primary site. To evaluate the guiding capability of PET-CT in biopsy site selection, we statisticallyanalyzed whether the biopsy site could be affected according to the presence of extra-skeletal FDG uptake. @*Results@#Among 74 enrolled patients, 51 patients had a metastatic bone disease. The primary site was identified in 48 of 51patients (94.1%). Forty-six patients were eligible to test the association of clinical choice of biopsy site with PET positivity ofextra-skeletal lesion. The extra-skeletal biopsies were done in 42 out of 43 patients with positive extra-skeletal uptake lesions.Bone biopsies were inevitably performed in the other three patients without extra-skeletal uptake lesions. The association cameout to be significant (Fisher’s exact test, P< 0.001). @*Conclusion@#F-18 FDG PET-CT significantly contributed not only to identify the primary site but also to suggest optimal biopsysites in patients with suspected bone metastasis.

Comparison of I-131 Biokinetics after Recombinant Human TSH Stimulation and Thyroid Hormone Withdrawal Measured by External Detector in Patients with Differentiated Thyroid Cancer / 전남의대학술지

The aim of this study was to compare radioactive iodine (I-131) biokinetics after recombinant human TSH stimulation (rhTSH) and thyroid hormone withdrawal (THW) in patients with differentiated thyroid cancer (DTC). External effective dose rates were measured using external detectors and imaged quantitatively at the time of discharge from the isolation wards. We retrospectively analyzed 32 patients who had been diagnosed with DTC, papillary or follicular, and underwent remnant ablation after either rhTSH stimulation (n=22) or THW (n=10). The uptake of I-131 by remnant thyroid tissue was measured from 20.0 cm, 100.0 cm and 200.0 cm distances using a handheld external detector. The remnant thyroid tissue measured by the whole body images two to five days from administration was 10.7+26.0% (range 0.5 to 60.0%). The values measured at 20 cm were best correlated to the thyroid residual uptake measured by SPECT/CT. The half-lives of I-131washout (T1/2) in rhTSH group measured by external detector were shorter than those of THW group. T1/2 becomes longer when it was measured over longer distances. They were 10.9, 12.3 and 13.1 hours at distances of 20, 100, and 200 cm in rhTSH group, respectively. The TWH group showed 12.8, 14.9 and 17.7 hours, respectively. We conclude that I-131 biokinetics can be measured by external detector after high dose I-131 therapy for DTC. It showed that washout of I-131 was faster after rhTSH stimulation than THW, and slower in patients with distant metastasis than those without metastasis.

Emerging Tracers for Nuclear Cardiac PET Imaging / 대한핵의학회잡지

Myocardial perfusion imaging using positron emission tomography (PET) has several advantages over single photon emission computed tomography (SPECT). The recent advances in SPECT technology have shown promise, but there is still a large need for PET in the clinical management of coronary artery disease (CAD). Especially, absolute quantification of myocardial blood flow (MBF) using PET is extremely important. In spite of considerable advances in the diagnosis of CAD, novel PET radiopharmaceuticals remain necessary for the diagnosis of CAD because clinical use of current cardiac radiotracers is limited by their physical characteristics, such as decay mode, emission energy, and half-life. Thus, the use of a radioisotope that has proper characteristics and a proper half-life to develop myocardial perfusion agents could overcome these limitations. In this review, the current state of cardiac PET and a general overview of novel ¹⁸F or ⁶⁸Ga-labeled radiotracers, including their radiosynthesis, in vivo characterization, and evaluation, are provided. The future perspectives are discussed in terms of their potential usefulness based on new image analysis methods and hybrid imaging.

Response Prediction of Altered Thyroglobulin Levels After Radioactive Iodine Therapy Aided by Recombinant Human Thyrotropin in Patients with Differentiated Thyroid Cancer / 대한핵의학회잡지

PURPOSE@#Thyroglobulin (Tg) may be released from damaged residual thyroid tissues after radioactive iodine (RAI) therapy in patients with differentiated thyroid carcinoma (DTC). We investigated whether altered levels of serum Tg after recombinant human thyrotropin (rhTSH)-aided RAI therapy could be a prognostic marker in patients with DTC.@*METHODS@#We evaluated 68 patients who underwent RAI therapy after total thyroidectomy. Serum Tg levels were measured just before RAI administration (D0Tg) and 7 days after RAI therapy (D7Tg). Patients with a D0Tg level greater than 2.0 ng/mL were excluded to more precisely evaluate the injury effect of RAI in small remnant tissues. The ratioTg was defined as the D7Tg level divided by that on D0Tg. The therapeutic responses were classified as acceptable or non-acceptable. Finally, we investigated which clinicopathologic parameters were associated with therapeutic response.@*RESULTS@#At the follow-up examination, an acceptable response was observed in 50 patients (73.5%). Univariate analysis revealed significant differences in N stage (P = 0.003) and ratioTg (acceptable vs. non-acceptable responses, 21.9 ± 33.6 vs. 3.8 ± 6.5; P = 0.006). In multivariate analysis, only ratioTg significantly predicted an acceptable response (odds ratio 1.104; 95% confidence interval 1.005–1.213; P = 0.040). A ratioTg above 3.5 predicted an acceptable response with a sensitivity of 66.0%, specificity of 83.3%, and accuracy of 70.6% (area under the curve = 0.718; P = 0.006).@*CONCLUSIONS@#Altered levels of serum Tg after RAI therapy, calculated as the ratioTg (D7Tg/D0Tg), significantly predicted an acceptable response in patients with DTC.

Emerging Tracers for Nuclear Cardiac PET Imaging / 대한핵의학회잡지

Myocardial perfusion imaging using positron emission tomography (PET) has several advantages over single photon emission computed tomography (SPECT). The recent advances in SPECT technology have shown promise, but there is still a large need for PET in the clinical management of coronary artery disease (CAD). Especially, absolute quantification of myocardial blood flow (MBF) using PET is extremely important. In spite of considerable advances in the diagnosis of CAD, novel PET radiopharmaceuticals remain necessary for the diagnosis of CAD because clinical use of current cardiac radiotracers is limited by their physical characteristics, such as decay mode, emission energy, and half-life. Thus, the use of a radioisotope that has proper characteristics and a proper half-life to develop myocardial perfusion agents could overcome these limitations. In this review, the current state of cardiac PET and a general overview of novel ¹⁸F or ⁶⁸Ga-labeled radiotracers, including their radiosynthesis, in vivo characterization, and evaluation, are provided. The future perspectives are discussed in terms of their potential usefulness based on new image analysis methods and hybrid imaging.

Response Prediction of Altered Thyroglobulin Levels After Radioactive Iodine Therapy Aided by Recombinant Human Thyrotropin in Patients with Differentiated Thyroid Cancer / 대한핵의학회잡지

PURPOSE: Thyroglobulin (Tg) may be released from damaged residual thyroid tissues after radioactive iodine (RAI) therapy in patients with differentiated thyroid carcinoma (DTC). We investigated whether altered levels of serum Tg after recombinant human thyrotropin (rhTSH)-aided RAI therapy could be a prognostic marker in patients with DTC.METHODS: We evaluated 68 patients who underwent RAI therapy after total thyroidectomy. Serum Tg levels were measured just before RAI administration (D0Tg) and 7 days after RAI therapy (D7Tg). Patients with a D0Tg level greater than 2.0 ng/mL were excluded to more precisely evaluate the injury effect of RAI in small remnant tissues. The ratioTg was defined as the D7Tg level divided by that on D0Tg. The therapeutic responses were classified as acceptable or non-acceptable. Finally, we investigated which clinicopathologic parameters were associated with therapeutic response.RESULTS: At the follow-up examination, an acceptable response was observed in 50 patients (73.5%). Univariate analysis revealed significant differences in N stage (P = 0.003) and ratioTg (acceptable vs. non-acceptable responses, 21.9 ± 33.6 vs. 3.8 ± 6.5; P = 0.006). In multivariate analysis, only ratioTg significantly predicted an acceptable response (odds ratio 1.104; 95% confidence interval 1.005–1.213; P = 0.040). A ratioTg above 3.5 predicted an acceptable response with a sensitivity of 66.0%, specificity of 83.3%, and accuracy of 70.6% (area under the curve = 0.718; P = 0.006).CONCLUSIONS: Altered levels of serum Tg after RAI therapy, calculated as the ratioTg (D7Tg/D0Tg), significantly predicted an acceptable response in patients with DTC.

Predictive Efficacy of Interim Positron Emission Tomography/Computed Tomography (PET/CT) for the Treatment of Aggressive Lymphoma / 전남의대학술지

The prognostic value of whole-body positron emission tomography/computed tomography (PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of induction chemotherapy or mid treatment could help to predict long-term clinical outcomes in patients with Hodgkin's or Non-Hodgkin's lymphoma. However, FDG is not a tumor-specific substance, and it may accumulate to the point of being detected in a variety of benign conditions or at physiologic anatomical sites, which may give rise to false-positive interpretation. In an attempt to standardize the reporting criteria for interim PET/CT, the First International Workshop on Interim PET in Lymphoma suggested visual response criteria with the Deauville five-point scale, and the standardized uptake value (SUV) has been investigated in comparison with this visual system. A quantitative approach using the measurement of maximal SUV (SUVmax) or the reduction rate of SUVmax (DeltaSUVmax) might be more appropriate in early-response PET/CT for reducing false-positive rates or for decreasing interobserver variability in interpretation. In this review, the predictive efficacy of PET/CT is discussed for the treatment of aggressive lymphoma, especially in terms of an interim PET/CT-based prognostic model.

Cardioprotective Effect of Fimasartan, a New Angiotensin Receptor Blocker, in a Porcine Model of Acute Myocardial Infarction

Cardioprotective effect of fimasartan, a new angiotensin receptor blocker (ARB), was evaluated in a porcine model of acute myocardial infarction (MI). Fifty swine were randomized to group 1 (sham, n=10), group 2 (no angiotensin-converting enzyme inhibitor [ACEI] or ARB, n=10), group 3 (perindopril 2 mg daily, n=10), group 4 (valsartan 40 mg daily, n=10), or group 5 (fimasartan 30 mg daily, n=10). Acute MI was induced by occlusion of the left anterior descending artery for 50 min. Echocardiography, single photon emission computed tomography (SPECT), and F-18 fluorodeoxyglucose cardiac positron emission tomography (PET) were performed at baseline, 1 week, and 4 weeks. Iodine-123 meta-iodobenzylguanidine (MIBG) scan was done at 6 weeks for visualization of cardiac sympathetic activity. Left ventricular function and volumes at 4 weeks were similar between the 5 groups. No difference was observed in groups 2 to 5 in SPECT perfusion defect, matched and mismatched segments between SPECT and PET at 1 week and 4 weeks. MIBG scan showed similar uptake between the 5 groups. Pathologic analysis showed similar infarct size in groups 2 to 5. Infarct size reduction was not observed with use of fimasartan as well as other ACEI and ARB in a porcine model of acute MI.

Predictive Efficacy of Interim Positron Emission Tomography/Computed Tomography (PET/CT) for the Treatment of Aggressive Lymphoma / 전남의대학술지

The prognostic value of whole-body positron emission tomography/computed tomography (PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of induction chemotherapy or mid treatment could help to predict long-term clinical outcomes in patients with Hodgkin's or Non-Hodgkin's lymphoma. However, FDG is not a tumor-specific substance, and it may accumulate to the point of being detected in a variety of benign conditions or at physiologic anatomical sites, which may give rise to false-positive interpretation. In an attempt to standardize the reporting criteria for interim PET/CT, the First International Workshop on Interim PET in Lymphoma suggested visual response criteria with the Deauville five-point scale, and the standardized uptake value (SUV) has been investigated in comparison with this visual system. A quantitative approach using the measurement of maximal SUV (SUVmax) or the reduction rate of SUVmax (DeltaSUVmax) might be more appropriate in early-response PET/CT for reducing false-positive rates or for decreasing interobserver variability in interpretation. In this review, the predictive efficacy of PET/CT is discussed for the treatment of aggressive lymphoma, especially in terms of an interim PET/CT-based prognostic model.

Effect of post-reconstruction gaussian filtering on image quality and myocardial blood flow measurement with N-13 ammonia PET

In order to evaluate the effect of post-reconstruction Gaussian filtering on image quality and myocardial blood flow [MBF] measurement by dynamic N-13 ammonia positron emission tomography [PET], we compared various reconstruction and filtering methods with image characteristics. Dynamic PET images of three patients with coronary artery disease [male-female ratio of 2:1; age: 57, 53, and 76 years] were reconstructed, using filtered back projection [FBP] and ordered subset expectation maximization [OSEM] methods. OSEM reconstruction consisted of OSEM_2I, OSEM_4I, and OSEM_6I with 2, 4, and 6 iterations, respectively. The images, reconstructed and filtered by Gaussian filters of 5, 10, and 15 mm, were obtained, as well as non-filtered images. Visual analysis of image quality [IQ] was performed using a 3-grade scoring system by 2 independent readers, blinded to the reconstruction and filtering methods of stress images. Then, signal-to-noise ratio [SNR] was calculated by noise and contrast recovery [CR]. Stress and rest MBF and coronary flow reserve [CFR] were obtained for each method. IQ scores, stress and rest MBF, and CFR were compared between the methods, using Chi-square and Kruskal-Wallis tests. In the visual analysis, IQ was significantly higher by 10 mm Gaussian filtering, compared to other sizes of filter [P<0.001 for both reader]. However, no significant difference of IQ was found between FBP and various numbers of iteration in OSEM [P=0.923 and 0.855 for readers 1 and 2 respectively]. SNR was significantly higher in 10 mm Gaussian filter. There was a significant difference in stress and rest MBF between several vascular territories. However CFR was not significantly different according to various filtering methods. Post-reconstruction Gaussian filtering with a filter size of 10 mm significantly enhances the IQ of N-13 ammonia PET-CT, without changing the results of CFR calculation

Indirect Radionuclide Coronary Angiography to Evaluate Gradients of Myocardial Blood Flow and Flow Reserve Through Coronary Stenosis Using N-13 Ammonia PET/CT / 전남의대학술지

Although quantitative evaluation of myocardial blood flow (MBF) and myocardial flow reserve (MFR) has been perceived as an attractive advantage of positron emission tomography (PET) over other cardiac imaging technologies, application of the information to specific coronary lesions is a difficult task for nuclear cardiologists. We hypothesized that changes in MBF and MFR over a coronary lesion could be identified by use of a hybrid technology of CT coronary angiography (CTCA) and N-13 ammonia PET. To evaluate this hypothesis, we measured the gradient of MBF and MFR through coronary stenosis in seven patients (M:F=3:4, median age 56 years) with coronary artery disease who underwent N-13 ammonia PET, CTCA, and interventional coronary angiography. Two patients had proximal left anterior descending (LAD) coronary artery disease and five patients had mid to distal LAD disease. Mean global stress and rest MBF were 2.62+/-0.58 and 1.03+/-0.19 ml/min/g, respectively. Mean global MFR was 2.6+/-0.73. Regional stress and rest MBF in the LAD territory were 2.36+/-0.75 and 0.96+/-0.21 ml/min/g, respectively. Regional MFR in the LAD territory was 2.55+/-0.83 ml/min/g. Stress MBF changed dramatically according to the location of coronary stenosis. It dropped acutely in proximal lesions, whereas it diminished gradually in mid to distal lesions. In conclusion, by use of a hybrid technology of CTCA and PET, it was feasible to make a direct correlation of coronary lesions with the gradient of MFR and CFR through coronary stenosis, which indicated the severity of the coronary lesion. We named this technique indirect radionuclide coronary angiography.

Clinical Usefulness of 18F-FDG PET/CT in the Detection of Early Recurrence in Treated Cervical Cancer Patients with Unexplained Elevation of Serum Tumor Markers / 전남의대학술지

We investigated the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for restaging of treated uterine cervix squamous cell cancer with tumor maker elevation that was not explained by other conventional evaluation. We enrolled 32 cases who underwent PET/CT for the restaging of treated cervical cancer with tumor marker elevation that was not explained by recent conventional evaluation. All enrolled cases had squamous cell carcinoma. Increased tumor markers included squamous cell carcinoma antigen (SCC Ag) and carcinoembryonic antigen (CEA). PET/CT findings were determined by pathologic confirmation or clinical follow-up. We compared PET/CT accuracy and clinical parameters including normalization of tumor markers in both the SCC Ag elevation group and the CEA elevation group. The sensitivity, specificity, positive predictive value, and negative predictive value of PET/CT in detecting recurrence were 100%, 83.3%, 82.4%, and 100%, respectively. Accuracy was significantly different between the SCC Ag elevation group and the CEA elevation group (p=0.0169). PET/CT with SCC Ag elevation was more accurate (100%) than PET/CT with CEA elevation (66.7%). Normalization of tumor markers was observed more often in the SCC Ag elevation group than in the CEA elevation group (p=0.0429). PET/CT showed high negative predictive value and sensitivity in the restaging of cervical cancer with unexplained tumor marker elevation. PET/CT was more accurate in patients with SCC Ag elevation than in those with CEA elevation.

Changes in 18F-Fluorodeoxyglucose Uptake in the Spinal Cord in a Healthy Population on Serial Positron Emission Tomography/Computed Tomography / 전남의대학술지

We aimed to determine the changes in 18F-fluorodeoxyglucose (FDG) uptake in the spinal cord on two serial positron emission tomography/computed tomography (PET/CT) scans in a healthy population. We retrospectively enrolled healthy people who underwent PET/CT twice for cancer screening. We excluded those who had degenerative vertebral disease, neurologic disease, or a history of a vertebral operation. The standardized uptake value (SUVmax) of the spinal cord of each mid-vertebral body was obtained by drawing a region of interest on an axial image of PET/CT. For analysis, the cord-to-background ratio (CTB) was used (CTB=SUVmax of each level/SUVmax of L5 level). Differences in pattern, sex, age, and intervals of the two serial PET/CT scans were analyzed. A total of 60 PET/CT images of 30 people were analyzed. The mean interval between the two PET/CT imaging studies was 2.80+/-0.94 years. On the follow-up PET/CT, significant change was shown only at the level of the C6 and T10 vertebrae (p<0.005). Mean CTB showed a decreasing pattern from cervical to lumbar vertebrae. There were two peaks at the lower cervical level (C4-6) and at the lower thoracic level (T12). Neither sex nor age significantly affected CTB. The FDG uptake of the spinal cord changed significantly on follow-up PET/CT only at the level of the C6 and T10 vertebrae. This finding is valuable as a baseline reference in the follow-up of metabolic changes in the spinal cord.

Both F-18 FDG-avidity and malignant shape of cervical lymph nodes on PET/CT after total thyroidectomy predict resistance to high-dose I-131 therapy in patients with papillary thyroid cancer

Resistance of metastatic lymph nodes [LNs] to high dose I-131 therapy is associated with high morbidity in patients with differentiated thyroid cancer. We evaluated the role of F-18 FDG PET/CT in the prediction of resistance to high dose I-131 therapy in patients with papillary thyroid cancer. The subjects were 307 patients who underwent total or near total thyroidectomy followed by high dose [5.55-6.66 GBq] I-131 therapy. We divided the patients into three subgroups by visual assessment of regional LNs: FDG-avid LNs with a malignant shape on CT [PET/CT-positive group], FDG-avid LNs with a benign shape on CT [PET/CT-intermediate group] and no FDG-avid lesion [PET/CT-negative group]. We measured the maximum SUV [SUVmax] of FDG-avid LNs in each patient. The presence or absence of focal increased uptake of I-131 was evaluated by whole body scan [WBS], and was denoted as WBS-positive group or WBS-negative group, respectively. Resistance to therapy was defined as presence of thyroglobulin [Tg] in serum [Tg >/= 1.0 ng/ml] 3-6 months after I-131 therapy. Univariate and multivariate analyses were performed to determine the relationship between resistance to I-131 therapy and various clinico-pathologic variables. PET/CT-positive, intermediate, and negative groups included 20 [6.5%], 44 [14.3%] and 243 [79.2%] patients, respectively. The mean SUVmax was significantly higher in the PET/CT-positive group than that of the PET/CT-intermediate group [4.6 vs.2.7, P <0.001]. Univariate analysis revealed that the PET/CT-positive group [P <0.001], T2-4 stage [P <0.001], N1b stage [P = 0.001], lower dose [5.55 GBq] of I-131 [P <0.001], and the WBS-positive group [P = 0.029] were associated with resistance to therapy. In multivariate analysis, the PET/CT-positive group, lower dose of I-131, N1b stage, and T2-4 stage remained significant with odds ratios of 10.07 [P <0.001], 3.82 [P <0.001], 3.58 [P = 0.001], and 2.53 [P = 0.009], respectively. FDG-avidity and malignant shape of cervical LNs on pre-therapy FDG PET/CT were a strong risk factors predicting resistance to high dose I-131 therapy. A lower dose of administered I-131 [5.55 GBq] and more extensive tumors [T2-4 and N1b] were also associated with resistance to high dose I-131 therapy

The Diagnosis and Management of Hyperthyroidism Consensus - Report of the Korean Thyroid Association / 대한갑상선학회지

No abstract available.

Changes in 18F-Fluorodeoxyglucose Uptake in the Spinal Cord in a Healthy Population on Serial Positron Emission Tomography/Computed Tomography / 전남의대학술지

We aimed to determine the changes in 18F-fluorodeoxyglucose (FDG) uptake in the spinal cord on two serial positron emission tomography/computed tomography (PET/CT) scans in a healthy population. We retrospectively enrolled healthy people who underwent PET/CT twice for cancer screening. We excluded those who had degenerative vertebral disease, neurologic disease, or a history of a vertebral operation. The standardized uptake value (SUVmax) of the spinal cord of each mid-vertebral body was obtained by drawing a region of interest on an axial image of PET/CT. For analysis, the cord-to-background ratio (CTB) was used (CTB=SUVmax of each level/SUVmax of L5 level). Differences in pattern, sex, age, and intervals of the two serial PET/CT scans were analyzed. A total of 60 PET/CT images of 30 people were analyzed. The mean interval between the two PET/CT imaging studies was 2.80+/-0.94 years. On the follow-up PET/CT, significant change was shown only at the level of the C6 and T10 vertebrae (p<0.005). Mean CTB showed a decreasing pattern from cervical to lumbar vertebrae. There were two peaks at the lower cervical level (C4-6) and at the lower thoracic level (T12). Neither sex nor age significantly affected CTB. The FDG uptake of the spinal cord changed significantly on follow-up PET/CT only at the level of the C6 and T10 vertebrae. This finding is valuable as a baseline reference in the follow-up of metabolic changes in the spinal cord.

Clinical Usefulness of 18F-FDG PET/CT in the Detection of Early Recurrence in Treated Cervical Cancer Patients with Unexplained Elevation of Serum Tumor Markers / 전남의대학술지

We investigated the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for restaging of treated uterine cervix squamous cell cancer with tumor maker elevation that was not explained by other conventional evaluation. We enrolled 32 cases who underwent PET/CT for the restaging of treated cervical cancer with tumor marker elevation that was not explained by recent conventional evaluation. All enrolled cases had squamous cell carcinoma. Increased tumor markers included squamous cell carcinoma antigen (SCC Ag) and carcinoembryonic antigen (CEA). PET/CT findings were determined by pathologic confirmation or clinical follow-up. We compared PET/CT accuracy and clinical parameters including normalization of tumor markers in both the SCC Ag elevation group and the CEA elevation group. The sensitivity, specificity, positive predictive value, and negative predictive value of PET/CT in detecting recurrence were 100%, 83.3%, 82.4%, and 100%, respectively. Accuracy was significantly different between the SCC Ag elevation group and the CEA elevation group (p=0.0169). PET/CT with SCC Ag elevation was more accurate (100%) than PET/CT with CEA elevation (66.7%). Normalization of tumor markers was observed more often in the SCC Ag elevation group than in the CEA elevation group (p=0.0429). PET/CT showed high negative predictive value and sensitivity in the restaging of cervical cancer with unexplained tumor marker elevation. PET/CT was more accurate in patients with SCC Ag elevation than in those with CEA elevation.

Indirect Radionuclide Coronary Angiography to Evaluate Gradients of Myocardial Blood Flow and Flow Reserve Through Coronary Stenosis Using N-13 Ammonia PET/CT / 전남의대학술지

Although quantitative evaluation of myocardial blood flow (MBF) and myocardial flow reserve (MFR) has been perceived as an attractive advantage of positron emission tomography (PET) over other cardiac imaging technologies, application of the information to specific coronary lesions is a difficult task for nuclear cardiologists. We hypothesized that changes in MBF and MFR over a coronary lesion could be identified by use of a hybrid technology of CT coronary angiography (CTCA) and N-13 ammonia PET. To evaluate this hypothesis, we measured the gradient of MBF and MFR through coronary stenosis in seven patients (M:F=3:4, median age 56 years) with coronary artery disease who underwent N-13 ammonia PET, CTCA, and interventional coronary angiography. Two patients had proximal left anterior descending (LAD) coronary artery disease and five patients had mid to distal LAD disease. Mean global stress and rest MBF were 2.62+/-0.58 and 1.03+/-0.19 ml/min/g, respectively. Mean global MFR was 2.6+/-0.73. Regional stress and rest MBF in the LAD territory were 2.36+/-0.75 and 0.96+/-0.21 ml/min/g, respectively. Regional MFR in the LAD territory was 2.55+/-0.83 ml/min/g. Stress MBF changed dramatically according to the location of coronary stenosis. It dropped acutely in proximal lesions, whereas it diminished gradually in mid to distal lesions. In conclusion, by use of a hybrid technology of CTCA and PET, it was feasible to make a direct correlation of coronary lesions with the gradient of MFR and CFR through coronary stenosis, which indicated the severity of the coronary lesion. We named this technique indirect radionuclide coronary angiography.