Preliminary Study for Quantitative Assessment of Sacroiliitis Activity Using Bone SPECT/CT: Comparison of Diagnostic Performance of Quantitative Parameters.

Purpose: We compared the feasibility of quantitative analysis methods using bone SPECT/CT with those using planar bone scans to assess active sacroiliitis. Methods: We retrospectively reviewed whole-body bone scans and pelvic bone SPECT/CTs of 8 patients who had clinically confirmed sacroiliitis and enrolled 24 patients without sacroiliitis as references. The volume of interest of each sacroiliac joint, including both the ilium and sacrum, was drawn. Active arthritis zone (AAZ) was defined as the zone of voxels with higher SUV than sacral mean SUV within the VOI of SI joint. Then, the following SPECT/CT quantitative parameters, SUVmax (maximum SUV), SUV50% (mean SUV in highest 50% of SUV), and SUV-AAZ, and the ratio of those values to sacral mean SUV (SUVmax/S, SUV50%/S, SUV-AAZ/S) were calculated. For the planar bone scan, the mean count ratio of SI joint/sacrum (SI/S) was conventionally measured. Results: Most of the SPECT/CT parameters of the sacroiliitis group were significantly higher than the normal group, whereas SI/S of the planar bone scan was not significantly different between the two groups. In receiver operating characteristic curve analysis, SUV-AAZ/S showed the highest AUC of 0.992, followed by SUV50%/S and SUVmax/S. All ratio parameters of the SPECT/CT showed higher AUC values than the SUV parameters of SI joint or SI/S of the planar scan. Conclusions: The quantitative analyses of bone SPECT/CT showed better performance in assessing active sacroiliitis than the planar bone scan. SPECT/CT parameters using the ratio of the SI joint to sacrum showed more favorable results than SUV parameters such as SUVmax, SUV50%, and SUV-AAZ.

Concordance between Response Assessment Using Prostate-Specific Membrane Antigen PET and Serum Prostate-Specific Antigen Levels after Systemic Treatment in Patients with Metastatic Castration Resistant Prostate Cancer: A Systematic Review and Meta-Analysis.

Prostate-specific membrane antigen positron emission tomography (PSMA PET) has recently gained interest as a promising tool for treatment response evaluation in metastatic castration-resistant prostate cancer (CRPC). We performed a systematic review and meta-analysis assessing the concordance between response evaluation using PSMA PET and serum prostate-specific antigen (PSA) level after systemic treatment and the association between PSMA PET and overall survival in metastatic CRPC patients. PubMed, Embase, and Cochrane library databases were searched until August 2020. Studies that reported the concordance between PSMA PET and PSA response were included. PSMA PET and PSA response evaluation were dichotomized into response vs. non-response to construct two-by-two contingency tables; an ≥30% increase in PSMA PET according to PET Response Criteria in Solid Tumors 1.0 and as an increase in serum PSA level of ≥25% as per Prostate Cancer Working Group 3 guidelines were defined as non-response. The percent agreement rates were pooled using random-effect model. Ten studies (268 patients) were included. The concordance rates ranged 0.50-0.84 with a pooled proportion of 0.73 (95% confidence interval 0.67-0.79). Patients were treated with 177Lu-PSMA therapy in five, chemotherapy in three, 223Ra in one, and more than one type in one study. Various PET parameters were used: the most widely evaluated was PSMA tumor volume (PSMA-TV). Similar proportions were found across different therapeutic agents, PET response parameters, and regarding directionality of discordance (PSA response/PSMA non-response vs. PSMA response/PSA non-response). Two studies reported that a decrease in PSMA-TV was associated with better overall survival. PSMA PET and PSA response assessments were discordant in nearly a fourth of metastatic CRPC patients. Further studies are warranted to establish the clinical meaning of this discordance and define appropriate management for such clinical situation.

Assessment of naive indolent lymphoma using whole-body diffusion-weighted imaging and T2-weighted MRI: results of a prospective study in 30 patients.

BACKGROUND: We prospectively evaluated the diagnostic utility of whole-body diffusion-weighted imaging with background body signal suppression and T2-weighted short-tau inversion recovery MRI (WB-DWIBS/STIR) for the pretherapeutic staging of indolent lymphoma in 30 patients. METHODS: This prospective study included 30 treatment-naive patients with indolent lymphomas who underwent WB-DWIBS/STIR and conventional imaging workup plus biopsy. The pretherapeutic staging agreement, sensitivity, and specificity of WB-DWIBS/STIR were investigated with reference to the multimodality and multidisciplinary consensus review for nodal and extranodal lesions excluding bone marrow. RESULTS: In the pretherapeutic staging, WB-DWIBS/STIR showed very good agreement (κ = 0.96; confidence interval [CI], 0.88-1.00), high sensitivity (93.4-95.1%), and high specificity (99.0-99.4%) for the whole-body regions. These results were similar to those of 18F-FDG-PET/CT, except for the sensitivity for extranodal lesions. For extranodal lesions, WB-DWIBS/STIR showed higher sensitivity compared to 18F-FDG-PET/CT for the whole-body regions (94.9-96.8% vs. 79.6-86.3%, P = 0.058). CONCLUSION: WB-DWIBS/STIR is an effective modality for the pretherapeutic staging of indolent lymphoma, and it has benefits when evaluating extranodal lesions, compared with 18F-FDG-PET/CT.

The role of ¹8F-fluorodeoxyglucose positron emission tomography at response assessment after autologous stem cell transplantation in T-cell non-Hodgkin's lymphoma patients.

Although a few studies have evaluated the utility of ¹8F-fluorodeoxyglucose positron emission tomography (FDG-PET) in treatment-naive T-cell non-Hodgkin's lymphomas (T-NHLs), a few studies had been conducted to evaluate the role of FDG-PET in patients after treatment. A total of 41 patients with T-NHLs were included who underwent post-autologous stem cell transplantation (ASCT) PET for response assessment in addition to contrast-enhanced CT. The impact of post-ASCT PET on response assessment and predicting prognosis was retrospectively evaluated. Of the 41 patients, 11 (26.8%) patients showed discordant response between two image modalities (Cohen's κ = 0.465). The additional PET study actually guides changing the post-ASCT response in six (54.5%) of these 11 patients. Moreover, positive post-ASCT PET was associated with worse prognosis in event-free survival and overall survival than negative post-ASCT PET (P = 0.003 and P = 0.044, respectively). Excluding four patients in whom further confirmation was not available due to early mortality, in 22 lesions showing discrepancy between two image modalities, 12 lesions were true positive (N = 4) or true negative (N = 8) for PET and ten lesions were false positive (N = 7) or false negative (N = 3). The accuracy for the discrepant lesions was 54.5% (12 of 22), the overall accuracy for the detected lesions was 76.7% (33 of 43), and the overall accuracy for patients was 89.2% (33 of 37). Post-ASCT PET was useful in response assessment after ASCT, and the positive post-ASCT PET result was associated with worse prognosis than the negative post-ASCT PET in patients with T-NHLs.

A pilot study for the early assessment of the effects of BMS-754807 plus gefitinib in an H292 tumor model by [(18)F]fluorothymidine-positron emission tomography.

BMS-754807 is an inhibitor of insulin-like growth factor-1 receptor (IGF-1R) and insulin receptor that also represses aurora kinase. Cancers that express high levels of IGF-1/IGF-1R are sensitive to BMS-754807; however, it shows limited efficacy in non-small cell lung cancer (NSCLC) in which IGF-1R-driven signals may not be dominant factors in cell proliferation. In this study, we investigated whether a combination of BMS-754807 and gefitinib would be synergistic in H292 NSCLC and whether [(18)F]fluorothymidine ([(18)F]FLT)-positron emission tomography (PET) could predict the effects. We found that BMS-754807 synergized with gefitinib in reducing cell viability (combination index=0.38) and Akt phosphorylation, and increasing the subG1 fraction in H292 cells. BMS-754807 alone and in combination with gefitinib increased the cells in G2M phase and polyploid cells and decreased the phosphorylation of IGF-1R and histone H3. The inhibition of tumor growth by gefitinib was increased by BMS-754807 (%T/C, 17.5 % vs. 58.0 % for gefitinib alone and combined treatment, respectively), although BMS-754807 alone had little effect. The standardized uptake value by [(18)F]FLT-PET were increased in vehicle-treated mice by 73 %, minimally changed in gefitinib- or BMS-754807-treated mice, whereas decreased in co-treated mice by -48.8 % between day 0 and day 3. The combination therapy with BMS-754807 and gefitinib might be a more effective anticancer strategy than BMS-754807 alone in tumors that are less IGF-1R-dependent and that [(18)F]FLT-PET can be used to assess early therapeutic responses.

Early assessment of tumor response to JAC106, an anti-tubulin agent, by 3'-deoxy-3'-[¹8F]fluorothymidine in preclinical tumor models.

PURPOSE: We determined whether [(18)F]fluorothymidine (FLT) positron emission tomography (PET) can detect early effects on tumor proliferation of JAC106, a new anti-tubulin agent. METHODS: Inhibition of tubulin polymerization and [(3)H]colchicine binding were assessed in vitro. The effects of JAC106 on cytotoxicity, mitotic arrest, [(18)F]FLT uptake, and thymidine kinase 1 (TK1) activity were examined in SW620 and KB-V1 cells. Dose-dependent antitumor effects of JAC106 were monitored by measuring tumor growth and by dynamic [(18)F]FLT PET imaging in mice bearing SW620 and KB-V1 tumors. The proliferation status of tumors was examined. RESULTS: JAC106 potently inhibited tubulin polymerization and decreased the viability of SW620 (p < 0.001, half maximal inhibitory concentration, IC(50) = 3.15 ± 1.4) and KB-V1 (p < 0.01, IC(50) = 21.84 ± 24.59) cells. Exposure to JAC106 induced mitotic arrest starting at 18 h and dose-dependently increased [(18)F]FLT uptake/1 × 10(5) cells (p < 0.05) and TK1 activity and expression in vitro. Administration of 30 mg/kg JAC106 to mice inhibited the growth of SW620 and KB-VI tumors (%T/C 3.34 and 20.6%, respectively). The baseline standardized uptake values (SUV) of SW620 and KB-V1 tumors were 0.96 ± 0.31 and 2.29 ± 0.70, respectively, with a significant difference (p < 0.01). After 3 days of treatment with 30 mg/kg JAC106, the [(18)F]FLT SUVs of SW620 and KB-V1 tumors, normalized to those before treatment, were 77.9 ± 22.4% (p = 0.059) and 43.2 ± 14.0% (p < 0.01), respectively. JAC106 significantly decreased the number of Ki-67-positive cells, TK1 activity, cell fraction in G(0)G(1) phase, and tumor expression of cyclins E, A, and B1 on day 3. CONCLUSION: [(18)F]FLT PET can be used to monitor JAC106 inhibition of tumor growth, beginning 3 days after treatment. Incorporation of [(18)F]FLT PET may be useful in the early clinical development of JAC106.

(18)F-FDG PET/CT is Useful for Pretreatment Assessment of the Histopathologic Type of Thymic Epithelial Tumors.

PURPOSE: This study was performed to assess the usefulness of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) or PET/computed tomography (CT) for distinguishing thymic epithelial tumors according to World Health Organization (WHO) classifications. METHODS: We analyzed a total of 45 patients (range, 29-75 years of age; mean, 55 years) with pathologically confirmed thymic epithelial tumors who underwent pretreatment (18)F-FDG PET or PET/CT between November 2003 and October 2009. The size, visual grading of uptake value, peak standardized uptake value (SUVpeak), uptake pattern, and contour of each tumor, and associated findings on PET or PET/CT, were analyzed relative to the three simplified WHO subgroups: less-invasive thymomas (types A and AB), more-invasive thymomas (types B1, B2, and B3) and thymic carcinomas. We statistically assessed the relationship of (18)F-FDG PET or PET/CT findings with these simplified subgroups. RESULTS: Of the 45 patients, ten had less-invasive thymomas, 23 had more-invasive thymomas, and 12 had thymic carcinomas. The SUVpeak of the less- and more-invasive thymomas were significantly lower than those of thymic carcinomas (p < 0.000), but there was no difference in SUVpeak between less- and more-invasive thymomas. The visual grading scale (p < 0.000), uptake pattern (p = 0.001), and contour (p < 0.000) of the tumors differed significantly among the three simplified subgroups. CONCLUSION: The image findings of (18)F-FDG PET or PET/CT differed significantly by histologic subgroups. Pre-treatment evaluation with (18)F-FDG PET or PET/CT might be helpful in differentiating subgroups of thymic epithelial tumors.