Prognostic significance of preoperative ¹⁸F-FDG PET/CT in uterine leiomyosarcoma

Objective

Uterine leiomyosarcoma (LMS) is a rare and aggressive disease with poor outcome. Due to its rarity and conflict of data, investigation on finding prognostic factor is challenging. The aim of the study was to investigate the prognostic significance of preoperative ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in uterine LMS.

Methods

This was a retrospective observational cohort study in 3 tertiary referral hospitals. We retrospectively evaluated data from patients with pathologically proven uterine LMS who underwent preoperative ¹⁸F-FDG PET/CT scans at 3 institutions. The prognostic implication of PET/CT parameters and other clinico-pathological parameters on disease-free survival (DFS) and overall survival (OS) was evaluated.

Results

Clinico-patholgical data were reviewed for 19 eligible patients. In the group overall, median DFS and OS were 12 and 20 months, respectively. As for the recurrence, large tumor size, and high tumor maximum standardized uptake value (SUV_max) were demonstrated as risk factors of recurrence. As for the OS, high tumor SUV_max was demonstrated as the unique risk factor. There were significant differences in tumor size, mitotic count, SUV_max, and DFS between patients with and without recurrence. Also, there were significant differences in tumor size, SUV_max, DFS, and OS between 2 subgroups stratified by cut-off SUV_max.

Conclusion

SUV_max at preoperative ¹⁸F-FDG PET/CT was associated with worse outcome in patients with uterine LMS. In the preoperative setting, SUV_max can be a valuable non-invasive prognostic marker. Additionally, SUV_max can help identify highly aggressive uterine LMS and may help in adjusting standard treatment toward an individualized, risk-adapted treatment.

Prospective evaluation of the clinical implications of the tumor metabolism and chemotherapy-related changes in advanced biliary tract cancer

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Background: Tumor metabolism measured by [18F] fluorodeoxy-D-glucose (18F-FDG) positron emission tomography (PET) has a diagnostic and prognostic role in several cancers. The clinical implication of tumor metabolism in biliary tract cancer (BTC) has not been studied well. Therefore, we prospectively evaluated the prognostic value of tumor metabolism and chemotherapy-related changes in advanced BTC patients. Methods: We prospectively enrolled advanced BTC patients before the initiation of palliative chemotherapy. Using 18F-FDG PET, we assessed the baseline maximum standardized uptake value (SUVmax) and monitored the changes of SUVmax during chemotherapy. We analyzed the associations between SUVmax, and clinicopathologic factors and clinical outcomes. Results: A total of 75 patients were enrolled. All patients received gemcitabine/cisplatin as first-line chemotherapy. Primary tumor site, histologic differentiation, molecular characteristics, laboratory findings, and disease extent were associated with the metabolic characteristics. The high metabolism group showed worse survival outcome [Hazard ratio (HR)=4.09, p=0.001 for progression-free survival (PFS); HR=2.61, p=0.019 for overall survival (OS)] than the low metabolism group. The lesser reduction of SUVmax during chemotherapy was also associated with worse outcome (HR=3.35, p=0.002 for PFS; HR=1.96, p=0.082 for OS). Considering both baseline tumor metabolic activity and chemotherapy-related changes in the tumor metabolism, patients with a low metabolism and a more reduction in metabolism obtained the best OS (20.7 months, p=0.013). Conclusions: Tumor metabolic activity and the chemotherapy-related changes in the metabolism were associated with prognosis in advanced BTC patients.

[11C]-(R)-PK11195 positron emission tomography in patients with complex regional pain syndrome: A pilot study

Complex regional pain syndrome (CRPS) is characterized by severe and chronic pain, but the pathophysiology of this disease are not clearly understood. The primary aim of our case-control study was to explore neuroinflammation in patients with CRPS using positron emission tomography (PET), with an 18-kDa translocator protein specific radioligand [C]-(R)-PK11195. [C]-(R)-PK11195 PET scans were acquired for 11 patients with CRPS (30-55 years) and 12 control subjects (30-52 years). Parametric image of distribution volume ratio (DVR) for each participant was generated by applying a relative equilibrium-based graphical analysis. The DVR of [C]-(R)-PK11195 in the caudate nucleus (t(21) = -3.209, P = 0.004), putamen (t(21) = -2.492, P = 0.022), nucleus accumbens (t(21) = -2.218, P = 0.040), and thalamus (t(21) = -2.395, P = 0.026) were significantly higher in CRPS patients than in healthy controls. Those of globus pallidus (t(21) = -2.045, P = 0.054) tended to be higher in CRPS patients than in healthy controls. In patients with CRPS, there was a positive correlation between the DVR of [C]-(R)-PK11195 in the caudate nucleus and the pain score, the visual analog scale (r = 0.661, P = 0.026, R = 0.408) and affective subscales of McGill Pain Questionnaire (r = 0.604, P = 0.049, R = 0.364). We demonstrated that neuroinflammation of CRPS patients in basal ganglia. Our results suggest that microglial pathology can be an important pathophysiology of CRPS. Association between the level of caudate nucleus and pain severity indicated that neuroinflammation in this region might play a key role. These results may be essential for developing effective medical treatments.

Bilateral Renal Metastasis of Hürthle Cell Thyroid Cancer with Discordant Uptake Between I-131 Sodium Iodide and F-18 FDG

Renal metastasis of thyroid cancer is extremely rare. We report the case of a 62-year-old woman with Hürthle cell thyroid cancer (HCTC) with lungs, bones, and bilateral kidneys metastases. The renal metastatic lesions were clearly demonstrated by ¹³¹I whole body scan (WBS) with SPECT/CT. However, they exhibited false-negative results in ¹⁸F-FDG PET/CT, kidney ultrasonography, and contrast-enhanced CT scan. The findings imply that tumors have low glucose metabolism and are able to accumulate radioiodine, which is not commonly found in the relatively aggressive nature of HCTC. The patient received two sessions of 200 mCi ¹³¹I therapy within 6 months duration. There was complete treatment response as evaluated by the second post-therapeutic ¹³¹I SPECT/CT and serum thyroglobulin. To our knowledge, renal metastasis from HCTC with positive ¹³¹I but negative ¹⁸F-FDG uptake has not been reported in the literature. This case suggests that ¹³¹I SPECT/CT is useful for lesion localization and prediction of ¹³¹I therapy response.

Prospective Evaluation of Changes in Tumor Size and Tumor Metabolism in Patients with Advanced Gastric Cancer Undergoing Chemotherapy: Association and Clinical Implication

A change in tumor size is a well-validated and commonly used value for evaluating response to chemotherapy in cancer. Metabolic changes induced by chemotherapy are related to prognosis in several tumor types. However, the clinical implication of metabolic changes in patients with advanced gastric cancer (AGC) undergoing chemotherapy remains unclear. We aimed to evaluate response of tumor size and metabolism in AGC during chemotherapy and to reveal the relationship between them in view of their impact on patient survival. Methods: We prospectively enrolled patients with AGC before the initiation of first-line palliative chemotherapy. Using baseline and follow-up contrast-enhanced CT and ¹⁸F-FDG PET, we assessed the tumor diameter, SUV_max, and total lesion glycolysis in each lesion and their changes during chemotherapy at the same time. We included all lesions with the maximal longest diameters over 1 cm on CT, and each lesion was evaluated by matched ¹⁸F-FDG PET. We analyzed the association between changes in tumor metabolism and tumor size and performed outcome analysis on overall survival (OS) and progression-free survival (PFS). Results: Seventy-four patients were enrolled, and the number of all lesions included in this study was 620. Compared with adenocarcinomas, poorly cohesive carcinomas demonstrated lower SUV_max irrespective of tumor size (P < 0.001). Human epidermal growth factor receptor 2 (HER2)-positive tumors showed higher SUV_max than HER2-negative tumors (P = 0.002). The changes in SUV_max due to chemotherapy had a linear correlation with the changes in tumor size of each lesion, and a 30% tumor size reduction was associated with a 50% SUV_max reduction (P < 0.001). Total lesion glycolysis changes also correlated with tumor size changes (P < 0.001). Better OS and PFS were obtained in patients with both tumor size and SUV_max reduction than in patients with either size or SUV_max reduction only (OS, P = 0.003; PFS, P = 0.038). Conclusion: Changes in tumor metabolism induced by chemotherapy correlated with changes in tumor size in AGC. Considering both changes in metabolism and size could help predict a more accurate prognosis for AGC patients undergoing chemotherapy.

Prognostic value of preoperative intratumoral FDG uptake heterogeneity in early stage uterine cervical cancer

OBJECTIVE

We investigated the prognostic value of intratumoral [¹⁸F]fluorodeoxyglucose (FDG) uptake heterogeneity (IFH) derived from positron emission tomography/computed tomography (PET/CT) in patients with cervical cancer.

METHODS

Patients with uterine cervical cancer of the International Federation of Obstetrics and Gynecology (FIGO) stage IB to IIA were imaged with [¹⁸F]FDG PET/CT before radical surgery. PET/CT parameters such as maximum and average standardized uptake values (SUV(max) and SUV(avg)), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and IFH were assessed. Regression analyses were used to identify clinicopathological and imaging variables associated with progression-free survival (PFS).

RESULTS

We retrospectively reviewed clinical data of 85 eligible patients. Median PFS was 32 months (range, 6 to 83 months), with recurrence observed in 14 patients (16.5%). IFH at an SUV of 2.0 was correlated with primary tumor size (p<0.001), SUV(tumor) (p<0.001), MTV(tumor) (p<0.001), TLG(tumor) (p<0.001), depth of cervical invasion (p<0.001), and negatively correlated with age (p=0.036). Tumor recurrence was significantly associated with TLG(tumor) (p<0.001), MTV(tumor) (p=0.001), SUV(LN) (p=0.004), IFH (p=0.005), SUV(tumor) (p=0.015), and FIGO stage (p=0.015). Multivariate analysis identified that IFH (p=0.028; hazard ratio, 756.997; 95% CI, 2.047 to 279,923.191) was the only independent risk factor for recurrence. The Kaplan-Meier survival graphs showed that PFS significantly differed in groups categorized based on IFH (p=0.013, log-rank test).

CONCLUSION

Preoperative IFH was significantly associated with cervical cancer recurrence. [¹⁸F]FDG based heterogeneity may be a useful and potential predicator of patient recurrence before treatment.

Integrated Myocardial Perfusion Imaging Diagnostics Improve Detection of Functionally Significant Coronary Artery Stenosis by 13 N-ammonia Positron Emission Tomography

Background—

Recent evidence suggests that the diagnostic accuracy of myocardial perfusion imaging is improved by quantifying stress myocardial blood flow (MBF) in absolute terms. We evaluated a comprehensive quantitative 13 N-ammonia positron emission tomography ( 13 NH 3 -PET) diagnostic panel, including stress MBF, coronary flow reserve (CFR), and relative flow reserve (RFR) in conjunction with relative perfusion defect (PD) assessments to better detect functionally significant coronary artery stenosis.

Methods and Results—

A total of 130 patients (307 vessels) with coronary artery disease underwent both 13 NH 3 -PET and invasive coronary angiography with fractional flow reserve (FFR) measurement. Diagnostic accuracy, optimal cut points, and discrimination indices of respective 13 NH 3 -PET quantitative measures were compared, with FFR as standard reference. The capacity to discern disease with stepwise addition of stress MBF, CFR, and RFR to qualitatively assessed relative PD was also gauged, using the category-free net reclassification index. All quantitative measures showed significant correlation with FFR (PET-derived CFR, r =0.388; stress MBF, r =0.496; and RFR, r =0.780; all P <0.001). Optimal respective cut points for FFR ≤0.8 and ≤0.75 were 1.99 and 1.84 mL/min per g for stress MBF and 2.12 and 2.00 for PET-derived CFR. Discrimination indices of quantitative measures that correlated with FFR ≤0.8 were all significantly higher than that of relative PD (area under the curve: 0.626, 0.730, 0.806, and 0.897 for relative PD, CFR, stress MBF, and RFR, respectively; overall comparison P <0.001). The capacity for functionally significant coronary stenosis was incrementally improved by the successive addition of CFR (net reclassification index=0.629), stress MBF (net reclassification index=0.950), and RFR (net reclassification index=1.253; all P <0.001) to relative PD.

Conclusions—

Integrating quantitative 13 NH 3 -PET measures with qualitative myocardial perfusion assessment provides superior diagnostic accuracy and improves the capacity to detect functionally significant coronary artery stenosis.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifiers: NCT01621438 and NCT01366404.

Diagnostic value of integrated PET/MRI for detection and localization of prostate cancer: Comparative study of multiparametric MRI and PET/CT

PURPOSE

To evaluate the diagnostic value of integrated positron emission tomography/magnetic resonance imaging (PET/MRI) compared with conventional multiparametric MRI and PET/computed tomography (CT) for the detailed and accurate segmental detection/localization of prostate cancer.

MATERIALS AND METHODS

Thirty-one patients who underwent integrated PET/MRI using ¹⁸ F-choline and ¹⁸ F-FDG with an integrated PET/MRI scanner followed by radical prostatectomy were included. The prostate was divided into six segments (sextants) according to anatomical landmarks. Three radiologists noted the presence and location of cancer in each sextant on four different image interpretation modalities in consensus (1, multiparametric MRI; 2, integrated ¹⁸ F-FDG PET/MRI; 3, integrated ¹⁸ F-choline PET/MRI; and 4, combined interpretation of 1 and ¹⁸ F-FDG PET/CT). Sensitivity, specificity, accuracy, positive and negative predictive values, likelihood ratios, and diagnostic performance based on the DOR (diagnostic odds ratio) and NNM (number needed to misdiagnose) were evaluated for each interpretation modality, using the pathologic result as the reference standard. Detection rates of seminal vesicle invasion and extracapsular invasion were also evaluated.

RESULTS

Integrated ¹⁸ F-choline PET/MRI showed significantly higher sensitivity than did multiparametric MRI alone in high Gleason score patients (77.0% and 66.2%, P = 0.011), low Gleason score patients (66.7% and 47.4%, P = 0.007), and total patients (72.5% and 58.0%, P = 0.008) groups. Integrated ¹⁸ F-choline PET/MRI and ¹⁸ F-FDG PET/MRI showed similar sensitivity and specificity to combined interpretation of multiparametric MRI and ¹⁸ F-FDG PET/CT (for sensitivity, 58.0%, 63.4%, 72.5%, and 68.7%, respectively, and for specificity, 87.3%, 80.0%, 81.8%, 72.7%, respectively, in total patient group). However, integrated ¹⁸ F-choline PET/MRI showed the best diagnostic performance (as DOR, 11.875 in total patients, 27.941 in high Gleason score patients, 5.714 in low Gleason score groups) among the imaging modalities, regardless of Gleason score. Integrated ¹⁸ F-choline PET/MRI showed higher sensitivity and diagnostic performance than did integrated ¹⁸ F-FDG PET/MRI (as DOR, 6.917 in total patients, 15.143 in high Gleason score patients, 3.175 in low Gleason score groups) in all three patient groups.

CONCLUSION

Integrated PET/MRI carried out using a dedicated integrated PET/MRI scanner provides better sensitivity, accuracy, and diagnostic value for detection/localization of prostate cancer compared to multiparametric MRI. Generally, integrated ¹⁸ F-choline PET/MRI shows better sensitivity, accuracy, and diagnostic performance than does integrated ¹⁸ F-FDG PET/MRI as well as combined interpretation of multiparametric MRI with ¹⁸ F-FDG PET/CT.

LEVEL OF EVIDENCE

2 J. Magn. Reson. Imaging 2017;45:597-609.

Plasmablastic lymphoma exclusively involving bones mimicking osteosarcoma in an immunocompetent patient: A case report

BACKGROUND

It has been known that plasmablastic lymphoma (PBL) is a neoplasm of immunocompromised patients occurring in soft tissue of oral cavity or in the vicinity whereas bone is an unlikely site to harbor PBL. However, its occurrence is increasingly being reported in immunocompetent individuals in either osseous or extra-oral sites. To our best knowledge, F-18 FDG PET/CT findings of PBL involving bones in an immunocompetent patient have not been reported, yet .

CASE SUMMARY

We report a case of PBL involving multiple bones in an immunocompetent patient. Features of different imaging modalities including F-18 Fluoro-deoxy glucose (FDG) positron emission tomography/computed tomography (PET/CT) were correlated well as findings of osteosarcoma in mandible with metastatic lesions. However, the histopathology and immunohistochemistry (IHC) of bone tissues from 2 separate biopsy sites revealed features of PBL.

CONCLUSION

awareness to F-18 FDG PET/CT findings of PBL involving bones in an immunocompetent patient may prevent misdiagnosis.

Fluorine-18 fluorodeoxyglucose positron emission tomography imaging of T-lymphoblastic lymphoma patients

The purpose of the present study was to evaluate the fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) findings in patients with T-lymphoblastic lymphoma (T-LBL). In total, 9 patients with histopathologically confirmed T-LBL were included in the study. Bone marrow (BM) involvement and leukemic transformation (LT) were evaluated through iliac crest marrow biopsy and peripheral blood blast count. FDG-PET scans were performed at the initial pre-treatment point. Two experienced nuclear medicine physicians evaluated the FDG-PET images by visual analysis and using the maximum standardized uptake values (SUVmax) of the malignant lesions. Overall, 8 out 9 patients presented with BM involvement; 7 showed LT, while 1 showed BM involvement without LT. All involved T-LBL lesions were FDG-avid with variable uptake. The mean SUVmax was 6.4±3.3. T-LBL patients with BM involvement showed diffuse or nodular marrow uptake. In addition, all the patients with LT showed diffuse marrow FDG activity. However, the patient with BM involvement but no LT showed nodular FDG uptake in the marrow. In conclusion, the present study indicates that it is possible to use FDG-PET for the evaluation of the disease extent of T-LBL. Furthermore, the imaging technique could provide a diagnostic clue for determining BM involvement or LT.

Association between partial-volume corrected SUVmax and Oncotype DX recurrence score in early-stage, ER-positive/HER2-negative invasive breast cancer

PURPOSE

Oncotype DX, a 21-gene expression assay, provides a recurrence score (RS) which predicts prognosis and the benefit from adjuvant chemotherapy in patients with early-stage, estrogen receptor-positive (ER-positive), and human epidermal growth factor receptor 2-negative (HER2-negative) invasive breast cancer. However, Oncotype DX tests are expensive and not readily available in all institutions. The purpose of this study was to investigate whether metabolic parameters on (18)F-FDG PET/CT are associated with the Oncotype DX RS and whether (18)F-FDG PET/CT can be used to predict the Oncotype DX RS.

METHODS

The study group comprised 38 women with stage I/II, ER-positive/HER2-negative invasive breast cancer who underwent pretreatment (18)F-FDG PET/CT and Oncotype DX testing. On PET/CT, maximum (SUVmax) and average standardized uptake values, metabolic tumor volume, and total lesion glycolysis were measured. Partial volume-corrected SUVmax (PVC-SUVmax) determined using the recovery coefficient method was also evaluated. Oncotype DX RS (0 - 100) was categorized as low (<18), intermediate (18 - 30), or high (≥31). The associations between metabolic parameters and RS were analyzed. Multivariate logistic regression was used to identify significant independent predictors of low versus intermediate-to-high RS.

RESULTS

Of the 38 patients, 22 (58 %) had a low RS, 13 (34 %) had an intermediate RS, and 3 (8 %) had a high RS. In the analysis with 38 index tumors, PVC-SUVmax was higher in tumors in patients with intermediate-to-high RS than in those with low RS (5.68 vs. 4.06; P = 0.067, marginally significant). High PVC-SUVmax (≥4.96) was significantly associated with intermediate-to-high RS (odds ratio, OR, 10.556; P = 0.004) in univariate analysis. In multivariate analysis with clinicopathologic factors, PVC-SUVmax ≥4.96 (OR 8.459; P = 0.013) was a significant independent predictor of intermediate-to-high RS.

CONCLUSIONS

High PVC-SUVmax on (18)F-FDG PET/CT was significantly associated with an intermediate-to-high Oncotype DX RS. PVC metabolic parameters on (18)F-FDG PET/CT can be used to predict the Oncotype DX RS in patients with early-stage, ER-positive/HER2-negative breast cancer.

Prognostic Value of Metabolic and Volumetric Parameters of Preoperative FDG-PET/CT in Patients With Resectable Pancreatic Cancer

In this study, we aimed to evaluate prognostic value of metabolic and volumetric parameters measured from F fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in patients with resectable pancreatic cancer.Fifty-one patients with resectable pancreatic cancer who underwent FDG-PET/CT and curative operation were retrospectively enrolled. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured from FDG-PET/CT. Association between FDG-PET/CT and clinicopathologic parameters was evaluated. The prognostic values of the FDG-PET/CT and clinicopathologic parameters for recurrence-free survival (RFS) and overall survival (OS) were assessed by univariate and multivariate analyses.The 51 enrolled patients were followed up for a median of 21 months (mean ± SD: 23 ± 16 months, range: 1-78 months) with 33 (65%) recurrences and 30 (59%) deaths during the period. SUVmax, MTV, and TLG were associated with Tumor node metastasis (TNM) stage and presence of lymph node metastasis. MTV and TLG were associated with presence of lymphovascular invasion, whereas SUVmax was not. On the univariate analysis, SUVmax, MTV, and TLG were associated with RFS and OS. Also, lymph node metastasis and TNM stage were associated with OS on the univariate analysis. On multivariate analysis, MTV and TLG were independent prognostic factors for RFS and OS. SUVmax was an independent prognostic factor for OS, but not for RFS.Metabolic tumor volume and TLG were independently predictive of RFS and OS in resectable pancreatic cancer. SUVmax was an independent factor for OS, but not for RFS.

FDG Whole-Body PET/MRI in Oncology: a Systematic Review

The recent advance in hybrid imaging techniques enables offering simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) in various clinical fields. ¹⁸F-fluorodeoxyglucose (FDG) PET has been widely used for diagnosis and evaluation of oncologic patients. The growing evidence from research and clinical experiences demonstrated that PET/MRI with FDG can provide comparable or superior diagnostic performance more than conventional radiological imaging such as computed tomography (CT), MRI or PET/CT in various cancers. Combined analysis using structural information and functional/molecular information of tumors can draw additional diagnostic information based on PET/MRI. Further studies including determination of the diagnostic efficacy, optimizing the examination protocol, and analysis of the hybrid imaging results is necessary for extending the FDG PET/MRI application in clinical oncology.

Prediction of Posttransplantation Recurrence of Hepatocellular Carcinoma Using Metabolic and Volumetric Indices of 18F-FDG PET/CT

(18)F-FDG PET is an effective method of predicting recurrence of hepatocellular carcinoma (HCC) after liver transplantation. We compared recently introduced metabolic and volumetric (18)F-FDG PET/CT indices with the current clinicopathologic predictors for ability to predict recurrence.

METHODS

In total, 110 HCC patients who underwent (18)F-FDG PET and liver transplantation were enrolled. On PET, SUVs and tumor-to-background ratios (TBRs) were measured as metabolic activity indices. Various metabolic tumor volumes and uptake-volume products (UVP) were also measured as volumetric indices. The ability of these indices and other clinicopathologic factors to predict recurrence was compared.

RESULTS

All metabolic and volumetric indices were significant for recurrence prediction on receiver-operating-characteristic curve analyses (P < 0.001). On univariate survival analyses, all PET indices-as well as tumor size, tumor number, the Milan criteria, tumor grade, vascular invasion, and T-stage-were significant factors. However, on multivariate analyses, tumor size, tumor grade, maximum TBR, and UVP calculated by inferior vena cava activity were significant factors (P = 0.004, 0.014, 0.009, and 0.021, respectively). When the Milan criteria and PET factors were included in the multivariate analysis, the Milan criteria (P = 0.029), maximum TBR (P < 0.001), and UVP (P = 0.016) were significant.

CONCLUSION

Volumetric and metabolic activity indices of (18)F-FDG PET are effective predictors of posttransplantation HCC recurrence. In addition to clinicopathologic factors, these indices need to be considered in the selection of candidates for liver transplantation.

Gray matter correlates of dopaminergic degeneration in Parkinson's disease: A hybrid PET/MR study using (18) F-FP-CIT

Dopaminergic degeneration is a hallmark of Parkinson's disease (PD), which causes various symptoms affected by corticostriatal circuits. So far, the relationship between cortical changes and dopamine loss in the striatum is unclear. Here, we evaluate the gray matter (GM) changes in accordance with striatal dopaminergic degeneration in PD using hybrid PET/MR. Sixteen patients with idiopathic PD underwent (18) F-FP-CIT PET/MR. To measure dopaminergic degeneration in PD, binding ratio (BR) of dopamine transporter in striatum was evaluated by (18) F-FP-CIT. Voxel-based morphometry (VBM) was used to evaluate GM density. We obtained voxelwise correlation maps of GM density according to the striatal BR. Voxel-by-voxel correlation between BR maps and GM density maps was done to evaluate region-specific correlation of striatal dopaminergic degeneration. There was a trend of positive correlation between striatal BR and GM density in the cerebellum, parahippocampal gyri, and frontal cortex. A trend of negative correlation between striatal BR and GM density in the medial occipital cortex was found. Voxel-by-voxel correlation revealed that the positive correlation was mainly dependent on anterior striatal BR, while posterior striatal BR mostly showed negative correlation with GM density in occipital and temporal cortices. Decreased GM density related to anterior striatal dopaminergic degeneration might demonstrate degeneration of dopaminergic nonmotor circuits. Furthermore, the negative correlation could be related to the motor circuits of posterior striatum. Our integrated PET/MR study suggests that the widespread structural progressive changes in PD could denote the cortical functional correlates of the degeneration of striatal dopaminergic circuits. Hum Brain Mapp 37:1710-1721, 2016. © 2016 Wiley Periodicals, Inc.

Radiation Dose from Whole-Body F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: Nationwide Survey in Korea

The purpose of this study was to estimate average radiation exposure from (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) examinations and to analyze possible factors affecting the radiation dose. A nation-wide questionnaire survey was conducted involving all institutions that operate PET/CT scanners in Korea. From the response, radiation doses from injected FDG and CT examination were calculated. A total of 105 PET/CT scanners in 73 institutions were included in the analysis (response rate of 62.4%). The average FDG injected activity was 310 ± 77 MBq and 5.11 ± 1.19 MBq/kg. The average effective dose from FDG was estimated to be 5.89 ± 1.46 mSv. The average CT dose index and dose-length product were 4.60 ± 2.47 mGy and 429.2 ± 227.6 mGy∙cm, which corresponded to 6.26 ± 3.06 mSv. The radiation doses from FDG and CT were significantly lower in case of newer scanners than older ones (P < 0.001). Advanced PET technologies such as time-of-flight acquisition and point-spread function recovery were also related to low radiation dose (P < 0.001). In conclusion, the average radiation dose from FDG PET/CT is estimated to be 12.2 mSv. The radiation dose from FDG PET/CT is reduced with more recent scanners equipped with image-enhancing algorithms.

Association of reduction of tumor metabolism with prognosis of advanced gastric cancer patients treated with palliative chemotherapy: Prospective cohort study

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Background: Although tumor metabolism can be measured by 18F-FDG PET, the meaning of metabolic response by chemotherapy in gastric cancer patients has not been well studied. The purpose of this study is to identify prognostic value of tumor metabolic response in gastric cancer. Methods: Advanced gastric cancer patients were enrolled in this prospective cohort study before initiation of palliative chemotherapy. At the baseline and at the first tumor response evaluation, 18F-FDG PET was taken to measure tumor metabolism. We measured maximum standardized uptake value (SUVmax), and total lesion glycolysis (TLG) calculated as multiplying mean SUV by metabolic tumor volume (MTV) using threshold SUVs of 2.5 (TLG2.5) in each patients. Correlation of clinicopathological factors and survival were analyzed. Results: A total of 87 patients were enrolled. Baseline high SUVmax and TLG2.5 were associated with HER2 positivity, histologic differentiation and tumor size. High SUVmax and TLG2.5 were also associated with worse overall survival (OS) (HR 2.14, P = 0.025; HR 2.23, P = 0.037, respectively). Comparing RECIST evaluation, 30% of the reduction of sum of target lesions was correlated with 50% reduction of SUVmax, and 50% reduction of TLG2.5. The larger reduction of SUVmax (HR 0.43, P = 0.006 for Progression-free survival (PFS); HR 0.38, P = 0.007 for OS), and TLG2.5 (HR 0.27, P < 0.001 for PFS; HR 0.27, P = 0.001 for OS) was associated with better OS. In multivariate analysis, SUVmax and TLG2.5 were independent prognostic factors along with age, histologic type, gastrectomy history and HER2 status. Conclusions: Tumor metabolic response measured by SUVmax or TLG2.5 was associated with prognosis of advanced gastric cancer patients treated with chemotherapy.

Increased (18)F-FDG uptake in the trapezius muscle in patients with spinal accessory neuropathy

To investigate (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) signal changes of denervated muscles in patients with electrophysiologically confirmed neuropathy.

METHODS

This is a case series of three cancer patients who were referred to the electromyography laboratory in 2013 due to shoulder discomfort after surgery including neck dissection. Spinal accessory neuropathy was diagnosed based on electrophysiological studies. Patients' medical history, electrophysiological data, and FDG-PET images were reviewed retrospectively. Mean standard uptake values (SUV) of trapezius muscles were measured.

RESULTS

The patients (3 men, aged 61-78years) showed spinal accessory neuropathy with different degrees of severity. In all patients, preoperative or postoperative FDG-PET showed increased FDG uptake in the ipsilateral trapezius muscle. These results were compatible with previously reported glucose hypermetabolism in denervated skeletal muscles.

CONCLUSION

This is the first clinical report of increased FDG uptake by denervated muscles in electrophysiologically confirmed neuropathy.

Prediction of microvascular invasion of hepatocellular carcinoma using gadoxetic acid-enhanced MR and (18)F-FDG PET/CT

PURPOSE

To identify the gadoxetic acid-enhanced MR and the (18)F-fludeoxyglucose (FDG) PET/CT findings associated with microvascular invasion (MVI) of hepatocellular carcinoma (HCC) in patients who are undergoing liver transplantation (LT).

METHODS

Fifty-one patients with 78 HCCs underwent LT. Preoperative MRI and (18)F-FDG PET/CT findings were retrospectively analyzed and the association of the imaging findings with MVI was assessed.

RESULTS

Univariate analysis revealed that hypointensity seen on T1WI (OR = 4.329, p = 0.011), peritumoral enhancement (OR = 7.000, p = 0.008), inhomogeneity on arterial phase (OR = 4.321, p = 0.011), delayed phase (OR = 4.519, p = 0.009) or hepatobiliary phase (OR = 3.564, p = 0.032), and the large tumor size (>5 cm) (OR = 12.091, p = 0.001) showed statistically significant associations with MVI. The ratio of tumor maximum standardized uptake value (SUV) to normal liver mean SUV (TSUVmax/LSUVmean) (2.05 ± 1.43 vs. 1.08 ± 0.37) revealed significantly higher value in the MVI-positive group. Multivariate analysis revealed that peritumoral enhancement and a TSUVmax/LSUVmean of 1.2 or greater had a statistically significant association with MVI, with odds ratios of 10.648 (p = 0.016) and 14.218 (p = 0.001), respectively.

CONCLUSIONS

Preoperative imaging findings such as peritumoral enhancement seen on gadoxetic acid-enhanced MR and a TSUVmax/LSUVmean of 1.2 or more on (18)F-FDG PET/CT, may suggest the presence of MVI in HCC patients.

FDG-PET in Mediastinal Nodal Staging of Non-small Cell Lung Cancer: Correlation of False Results with Histopathologic Finding

PURPOSE

Mediastinal staging of non-small cell lung cancer can be markedly improved by FDG-PET scan, but the problem of false staging of mediastinal nodes by PET scan in non-small cell lung cancer has not yet been overcome. The aim of this study was to identify the mechanism underlying the false staging of mediastinal nodes by FDG-PET in the case of non-small cell lung cancer.

MATERIALS AND METHODS

To evaluate the factors determining the FDG uptake in mediastinal nodes, FDG-PET was performed preoperatively, and mediastinal dissection with pulmonary resection was performed in 62 patients with NSCLC. GLUT-1 expression was studied by immunohistochemistry of the mediastinal nodes (n=111, true positive <TP> 31, true negative <TN> 41, false positive <FP> 27, false negative <FN> 12) using the anti-GLUT-1 antibody. The size, percentage of tumor (tumor ratio), labeling index (rate of stained tumor), staining intensity of the tumor, level of follicular hyperplasia, and staining intensity of the follicle center in the mediastinal node were also studied.

RESULTS

There was no significant difference in size among the 4 nodal groups (TP, TN, FP, FN), nor in the tumor ratio of the metastatic nodes between the TP and FN groups. The labeling index and staining intensity of the TP group were higher than those of the FN group (Mann-Whitney test, p=.001, p=.007) in the case of the metastatic nodes. The level of follicular hyperplasia of the FP group was higher than that of the TN group in the case of the non-metastatic nodes (p=.000).

CONCLUSION

These results suggest that in mediastinal staging of non-small cell lung cancer by FDG-PET, the FN node is associated with low uptake of FDG due to low expression of GLUT-1, and that the FP node is associated with a high level of follicular hyperplasia as a result of there being a reactive change to an inflammatory and/or immune reaction. This is the first report on the mechanism underlying the false results that are sometimes obtained, and which constitute a major problem in the clinical application of FDG-PET to the mediastinal staging of non-small cell lung cancer.

Malignant Peritoneal Mesothelioma Masquerades as Peritoneal Metastasis on (18)F-FDG PET/CT Scans; a Rare Diagnosis that Should Not Be Missed

Malignant peritoneal mesothelioma (MPM) is a rare but fatal tumor. The clinical presentations and imaging findings are nonspecific and resemble various diseases, including peritoneal metastasis. Imaging findings of MPH on (18)F-(18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT) are diverse and not well described. We report the two cases of biopsy-proven MPH using (18)F-FDG PET/CT. In our cases, interesting disease patterns-including MPH arising from visceral peritoneal lining of kidney that suffer from polycystic disease and from the parietal peritoneum beneath the appendectomy scar-were presented. One case showed classical metastases localized within the abdominal cavity; while the other case exhibited the rare pattern of extensive multi-organ metastases. By knowing the possible variations and diagnostic pitfalls of (18)F-FDG PET/CT findings in MPM, more accurate interpretation of such mysterious cancer is attainable.

Hemodynamic Significance of Internal Carotid or Middle Cerebral Artery Stenosis Detected on Magnetic Resonance Angiography

PURPOSE

We evaluated hemodynamic significance of stenosis on magnetic resonance angiography (MRA) using acetazolamide perfusion single photon emission computed tomography (SPECT).

MATERIALS AND METHODS

Of 171 patients, stenosis in internal carotid artery (ICA) and middle cerebral artery (MCA) (ICA-MCA) on MRA and cerebrovascular reserve (CVR) of MCA territory on SPECT was measured using quantification and a 3-grade system. Stenosis and CVR grades were compared with each other, and their prognostic value for subsequent stroke was evaluated.

RESULTS

Of 342 ICA-MCA, 151 (44%) presented stenosis on MRA; grade 1 in 69 (20%) and grade 2 in 82 (24%) cases. Decreased CVR was observed in 9% of grade 0 stenosis, 25% of grade 1, and 35% of grade 2. The average CVR of grade 0 was significantly different from grade 1 (p<0.001) and grade 2 stenosis (p=0.007). In quantitative analysis, average CVR index was -0.56±7.91 in grade 0, -1.81±6.66 in grade 1 and -1.18±5.88 in grade 2 stenosis. Agreement between stenosis and CVR grades was fair in patients with lateralizing and non-lateralizing symptoms (κ=0.230 and 0.346). Of the factors tested, both MRA and CVR were not significant prognostic factors (p=0.104 and 0.988, respectively), whereas hypertension and renal disease were significant factors (p<0.05, respectively).

CONCLUSION

A considerable proportion of ICA-MCA stenosis detected on MRA does not cause CVR impairment despite a fair correlation between them. Thus, hemodynamic state needs to be assessed for evaluating significance of stenosis, particularly in asymptomatic patients.