18F-FDG PET-CT Imaging Research Articles

Concurrent focal fat sparing and peritumoral fat sparing in diffuse fatty liver identified on 18F-FDG PETCT and multiparametric magnetic resonance imaging

Concurrent focal fat sparing and peritumoral fat sparing in diffuse fatty liver identified on 18F-FDG PETCT and multiparametric magnetic resonance imaging

Rare skin and testicular extranodal involvement in a patient with marginal zone lymphoma on 18F-FDG PET-CT imaging

Rare skin and testicular extranodal involvement in a patient with marginal zone lymphoma on 18F-FDG PET-CT imaging

A Prospective Study Comparing Functional Imaging (18F-FDG PET) Versus Anatomical Imaging (Contrast Enhanced CT) in Dosimetric Planning for Non-small Cell Lung Cancer.

Objective(s):18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the 18F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning.Methods:Eighteen patients were subjected to 18F- FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated.Results:The comparison of the primary gross tumour volume (GTV) between the 18F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the 18F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the 18F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm3 on the 18F-FDG PET-CT. The comparison of the GTV lymph node between the 18F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the 18F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the 18F-FDG PET-CT. The decrease in the GTV lymph node on the 18F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues.Conclusion:GTV may either increase or decrease with the 18F-FDG PET-CT, compared to the CECT. However, the 18F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.

Predictive value of metabolic tumor volume and total lesion glycolysis in 18F-FDG PET-CT imaging for postoperative recurrence and prognosis in patients with pancreatic cancer

Objective To investigate the predictive value of metabolic tumor volume(MTV) and total lesion glycolysis (TLG) calculated from 18F-FDG PET-CT results for postoperative recurrence and prognosis in patients with resectable pancreatic cancer. Methods From may 2009 to December 2015, 30 patients with pancreatic cancer who underwent curative resection after PET-CT examination were enrolled, and the clinic pathological data and 18F-FDG PET-CT data were retrospectively analyzed. The prognostic value of SUVmax, SUVmean, MTV, TLG and other prognosis factors were analyzed. Results In 30 patients with pancreatic cancer, preoperative 18F-FDG PET-CT detected all primary lesion (10 0%). 29 patients were recurrence or metastasis, and 26 patients were died with median of 17.8 months (2.6-39.6 months) follow-up. The median progression-free survival (PFS) time was 6.5 months and the median overall survival(OS) time was 11.6 months. The multivariate analysis revealed the histological differentiation and MTV were the independent influencing factors for PFS (both P<0.05). The lymph node metastasis, MTV and TLG were the independent influencing factors for OS (all P<0.05). Conclusion The MTV and TLG of PET-CT may be predicting the recurrence and survival of patients with pancreatic cancer after curative resection, suggesting that it can be used to guide the individual treatment. Key words: Pancreatic neoplasms; Prognosis; Metabolic tumor volume; Deoxyglucose

Use of 18F-FDG PET-CT imaging to determine internal mammary lymph node location for radiation therapy treatment planning in breast cancer patients

PurposeAdjuvant internal mammary lymph node (IMN) radiation is often delivered with 2-dimensional techniques that use anatomic landmarks and predetermined depths for field placement and dose specification. In contrast, 3-dimensional planning uses the internal mammary vessels (IMVs) to localize the IMNs for planning. Our purpose was to determine if localization of the involved IMN (i-IMN) by 18F-labeled fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) offers opportunities to improve treatment. Methods and materialsBreast cancer patients (n = 80) who had i-IMNs (n = 112) on PET-CT for initial staging (n = 40) or recurrence (n = 40) were studied. Size, intercostal space (IC), and distance from skin, sternum, and IMVs were recorded. Effects on 2- and 3-dimensional planning were evaluated. ResultsMost i-IMNs (94.6%) were in the first to third ICs. Few were in the fourth (4.5%) or fifth (0.9%) IC. Mean i-IMN depth was 3.4 cm (range, 1.1-7.3 cm). Prescriptive depths of 4, 5, and 6 cm would result in undertreatment of 25%, 10.7%, and 5.3% of IMNs, respectively. Most IMNs (86.6%) were lateral or adjacent to the sternal edge. Only 13.4% of IMNs were posterior to the sternum. Use of the ipsilateral or contralateral sternal edge for field placement increases the risk of geographic miss or excess normal tissue exposure. Most i-IMNs were adjacent to (83%) or ≤0.5 cm (14%) from the IMV edge. Three (3%) were >0.5 cm beyond the IMV edge. The clinical target volume (CTV) defined by the first to third ICs encompassed 78% of i-IMNs. IMN-CTV coverage of i-IMNs increased with inclusion of the fourth IC (82%), 0.5 cm medial and lateral margin expansion (93%), or both (96.5%). ConclusionTwo-dimensional treatment techniques risk geographic miss of IMNs and exposure of excess normal tissue to radiation. An IMN-CTV defined by the IMVs from the first to third ICs with 0.5-cm medial and lateral margin expansion encompasses almost all i-IMNs identified on PET-CT imaging. Inclusion of the fourth IC offers modest coverage improvement, and its inclusion should be weighed against potential increase in cardiac exposure. SummaryThe use of 2-dimensional treatment techniques for adjuvant internal mammary lymph node (IMN) radiation may cause geographic miss of tumor and expose normal tissue to radiation injury. Conformal 3-dimensional planning improves coverage and reduces risk of normal tissue damage by using the internal mammary vessel to define an IMN clinical target volume (CTV). Contouring the IMN-CTV from the first to third intercostal spaces with a 0.5-cm expansion medially and laterally encompasses most IMN. Positron emission tomography-computed tomography may have a role in radiation planning by identifying involved-IMN for dose escalation.

Sternal metastasis from dedifferentiated thyroid cancer: Value of 18F-fluorodeoxyglucose positron emission tomography–computed tomography imaging in thyroglobulin elevated negative iodine scan syndrome

Differentiated thyroid cancers are generally iodine avid and have an indolent growth rate. Dedifferentiation of thyroid cancer is rare and is commonly accompanied with more aggressive growth, metastatic spread, and loss of iodine avidity. 18F-fluorodeoxyglucose positron emission tomography–computed tomography (18F FDG PET–CT) plays an important role in identifying the extent of dedifferentiated disease and aids further management. The present case highlights the importance of 18F FDG PET-CT imaging in thyroglobulin elevated negative iodine scan syndrome clinically presenting with sternal metastasis.

18F-FDG PET-CT Findings Before and After Laparoscopic Cryoablation of Small Renal Mass: An Initial Report.

The aim of this study was to describe the characteristics of positron emission tomography (PET) molecular imaging combined with low-dose computed tomography (CT) in small renal mass (SRM) treated with cryoablation (CA). Currently, treatment success is defined by the absence of contrast enhancement at CT. However, the use of contrast is relatively contraindicated in patients with renal function impairment, mandating alternative follow-up strategies. Several reasons were identified as criteria for performing PET-CT before and/or after SRM-CA in 9 patients, and the results were retrospectively studied. The histology revealed renal cell carcinoma in 7 patients and oncocytoma in 2 patients. In 6 patients, a PET-CT was performed before and after CA. In one patient, the PET-CT was performed only before CA and in 2 patients only after CA. Before CA, clearly there was metabolic uptake of fluorine-18 fluorodeoxyglucose (18F-FDG) in the SRM in all patients. Following CA, the absence of 18F-FDG uptakes in the SRM could clearly be noticed. However, the tracer cannot always be distinguished from focal recurrence or reactive inflammatory tissue. In one patient, asymptomatic metastatic bone lesions were noticed when performing PET-CT at follow-up. This pilot study with 18F-FDG PET-CT for the follow-up of SRM cryosurgery showed that 18F-FDG PET-CT imaging could be used to characterize cryoablative tissue injury at different times after CA.

An unusual case of pituitary pathology and the utility of whole body 18F-FDG PET-CT imaging in identifying extraneural biopsy targets

An unusual case of pituitary pathology and the utility of whole body 18F-FDG PET-CT imaging in identifying extraneural biopsy targets

Value of 18F-FDG PET-CT in monitoring recurrence and metastasis of small intestinal adenocarcinoma

Objective To evaluate the clinical value of 18F-FDG PET-CT imaging on monitoring recurrence, metastasis and therapeutic decision-making in small intestinal adenocarcinoma patients after radical surgery. Methods Twenty-two patients were enrolled, who underwent surgical operation before received PET-CT scan. PET-CT findings were retrospectively observed to compare with the results of follow-up [postoperative pathology and (or) long-term clinical follow-up]. The roles of PET-CT on therapeutic decision-making were then investigated. Results Among 22 patients, 14 cases were finally diagnosed as recurrence and (or) metastasis, the other 8 cases as disease-free survival after long-term follow-up. According to PET-CT, 13 cases were diagnosed as recurrence and (or) metastasis (including 12 true-positive and 1 false-positive), and 9 cases were negative (including 2 false-negative). The diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of PET-CT were 85.7 % (12/14), 87.5 % (7/8), 86.4 % (19/22), 92.3 % (12/13) and 77.8 % (7/9), respectively. The therapeutic decisions were changed in 10 patients (10/22, 45.5 % ) based on PET-CT results. Conclusion 18F-FDG PET-CT has an important clinical value on the detection of recurrence and (or) metastasis of small intestinal adenocarcinoma, which is an ideal method of monitoring. Key words: Small intestinal neoplasms; Positron-emission tomography; Fluorine-18 fluoro-deoxy-glucose; Recurrence; Neoplasm metastasis

Value of 18F-FDG PET-CT in predicting the WHO grade of malignancy in thymic epithelial tumors

Objective To investigate the value of18F-FDG PET-CT in predicting the simplified WHO grade of malignancy in thymic epithelial tumors. Methods The 18F-FDG PET-CT imaging of forty-five patients with pathologically proven thymic epithelial tumors was analyzed retrospectively. The patients were subdivided into a low-risk group and a high-risk group based on the simplified WHO histological classification. Spearman rank correlation analysis was used to determine the relation between parameters of PET-CT and simplified WHO histological classification. An univariate logistic regression analysis and ROC curve were performed for assessing the ability of 18F-FDG PET-CT as a predictor of the simplified WHO classification. Results There were ten patients classified into low-risk group, and thirty-five patients classified into high-risk group. Both SUVmax and SUVmax / T showed significant relationship with patients subgroup (Spearman correlation coefficients were 0.577 and 0.621, respectively, P<0.000 1). The SUVmax and SUVmax /T were found to be predictive factors that were useful to distinguish high-risk tumor from low-risk tumor(area under the ROC curve were 0.888 and 0.917, respectively, P<0.000 1). Conclusions A significant relationship is observed between 18F-FDG PET-CT findings and histological WHO classification of thymic epithelial tumors. PET-CT may be useful for predicting the grad of malignancy in thymic epithelial tumors. Key words: Thymic epithelial tumors; Histological classification; Fluorodeoxyglucose F18; Positron-emission tomography

Imaging human brown adipose tissue under room temperature conditions with 11C-MRB, a selective norepinephrine transporter PET ligand

IntroductionBrown adipose tissue (BAT) plays a critical role in adaptive thermogenesis and is tightly regulated by the sympathetic nervous system (SNS). However, current BAT imaging modalities require cold stimulation and are often unreliable to detect BAT in the basal state, at room temperature (RT). We have shown previously that BAT can be detected in rodents under both RT and cold conditions with 11C-MRB ((S,S)-11C-O-methylreboxetine), a highly selective ligand for the norepinephrine transporter (NET). Here, we evaluate this novel approach for BAT detection in adult humans under RT conditions. MethodsTen healthy, Caucasian subjects (5 M: age 24.6±2.6, BMI 21.6±2.7kg/m2; 5 F: age 25.4±2.1, BMI 22.1±1.0kg/m2) underwent 11C-MRB PET-CT imaging for cervical/supraclavicular BAT under RT and cold-stimulated conditions (RPCM Cool vest; enthalpy 15°C) compared to 18F-FDG PET-CT imaging. Uptake of 11C-MRB, was quantified as the distribution volume ratio (DVR) using the occipital cortex as a low NET density reference region. Total body fat and lean body mass were assessed via bioelectrical impedance analysis. ResultsAs expected, 18F-FDG uptake in BAT was difficult to identify at RT but easily detected with cold stimulation (p=0.01). In contrast, BAT 11C-MRB uptake (also normalized for muscle) was equally evident under both RT and cold conditions (BAT DVR: RT 1.0±0.3 vs. cold 1.1±0.3, p=0.31; BAT/muscle DVR: RT 2.3±0.7 vs. cold 2.5±0.5, p=0.61). Importantly, BAT DVR and BAT/muscle DVR of 11C-MRB at RT correlated positively with core body temperature (r=0.76, p=0.05 and r=0.92, p=0.004, respectively), a relationship not observed with 18F-FDG (p=0.63). Furthermore, there were gender differences in 11C-MRB uptake in response to cold (p=0.03), which reflected significant differences in the change in 11C-MRB as a function of both body composition and body temperature. ConclusionsUnlike 18F-FDG, the uptake of 11C-MRB in BAT offers a unique opportunity to investigate the role of BAT in humans under basal, room temperature conditions.

Nomogram predicting response after chemoradiotherapy in rectal cancer using sequential PETCT imaging: A multicentric prospective study with external validation

PurposeTo develop and externally validate a predictive model for pathologic complete response (pCR) for locally advanced rectal cancer (LARC) based on clinical features and early sequential 18F-FDG PETCT imaging. Materials and methodsProspective data (i.a. THUNDER trial) were used to train (N=112, MAASTRO Clinic) and validate (N=78, Università Cattolica del S. Cuore) the model for pCR (ypT0N0). All patients received long-course chemoradiotherapy (CRT) and surgery. Clinical parameters were age, gender, clinical tumour (cT) stage and clinical nodal (cN) stage. PET parameters were SUVmax, SUVmean, metabolic tumour volume (MTV) and maximal tumour diameter, for which response indices between pre-treatment and intermediate scan were calculated. Using multivariate logistic regression, three probability groups for pCR were defined. ResultsThe pCR rates were 21.4% (training) and 23.1% (validation). The selected predictive features for pCR were cT-stage, cN-stage, response index of SUVmean and maximal tumour diameter during treatment. The models’ performances (AUC) were 0.78 (training) and 0.70 (validation). The high probability group for pCR resulted in 100% correct predictions for training and 67% for validation. The model is available on the website www.predictcancer.org. ConclusionsThe developed predictive model for pCR is accurate and externally validated. This model may assist in treatment decisions during CRT to select complete responders for a wait-and-see policy, good responders for extra RT boost and bad responders for additional chemotherapy.

Circulating Tumor Microemboli Diagnostics for Patients with Non–Small-Cell Lung Cancer

Circulating tumor microemboli (CTM) are potentially important cancer biomarkers, but using them for cancer detection in early-stage disease has been assay limited. We examined CTM test performance using a sensitive detection platform to identify stage I non-small-cell lung cancer (NSCLC) patients undergoing imaging evaluation. First, we prospectively enrolled patients during 18F-FDG PET-CT imaging evaluation for lung cancer that underwent routine phlebotomy where CTM and circulating tumor cells (CTCs) were identified in blood using nuclear (DAPI), cytokeratin (CK), and CD45 immune-fluorescent antibodies followed by morphologic identification. Second, CTM and CTC data were integrated with patient (age, gender, smoking, and cancer history) and imaging (tumor diameter, location in lung, and maximum standard uptake value [SUVmax]) data to develop and test multiple logistic regression models using a case-control design in a training and test cohort followed by cross-validation in the entire group. We examined 104 patients with NSCLC, and the subgroup of 80 with stage I disease, and compared them to 25 patients with benign disease. Clinical and imaging data alone were moderately discriminating for all comers (Area under the Curve [AUC] = 0.77) and by stage I disease only (AUC = 0.77). However, the presence of CTM combined with clinical and imaging data was significantly discriminating for diagnostic accuracy in all NSCLC patients (AUC = 0.88, p value = 0.001) and for stage I patients alone (AUC = 0.87, p value = 0.002). CTM may add utility for lung cancer diagnosis during imaging evaluation using a sensitive detection platform.

Fluorine-18 fluorodeoxyglucose PET-CT for extranodal staging of non-Hodgkin and Hodgkin lymphoma

We aimed to evaluate the role of fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) involving care-dose unenhanced CT to detect extranodal involvement in patients with non-Hodgkin and Hodgkin lymphoma. Lymphoma patients (35 Hodgkin lymphoma, 75 non-Hodgkin lymphoma) who were referred for 18F-FDG PET-CT imaging, following a diagnostic contrast-enhanced CT (CE-CT) performed within the last month, were included in our study. A total of 129 PET-CT images, and all radiologic, clinical, and pathological records of these patients were retrospectively reviewed. In total, 137 hypermetabolic extranodal infiltration sites were detected by 18F-FDG PET-CT in 62 of 110 patients. There were no positive findings by CE-CT that reflected organ involvement in 40 of 137 18F-FDG-positive sites. The κ statistics revealed fair agreement between PET-CT and CE-CT for the detection of extranodal involvement (κ=0.60). The organs showing a disagreement between the two modalities were the spleen, bone marrow, bone, and thyroid and prostate glands. In all lesions that were negative at CE-CT, there was a diffuse 18F-FDG uptake pattern in the PET-CT images. The frequency of extranodal involvement was 51% and 58% in Hodgkin and non-Hodgkin lymphoma patients, respectively. There was a high positive correlation between the maximum standardized uptake values of the highest 18F-FDG-accumulating lymph nodes and extranodal sites (r=0.67) in patients with nodal and extranodal involvement. 18F-FDG PET-CT is a more effective technique than CE-CT for the evaluation of extranodal involvement in Hodgkin and non-Hodgkin lymphoma patients. PET-CT has a significant advantage for the diagnosis of diffusely infiltrating organs without mass lesions or contrast enhancement compared to CE-CT.

The diagnostic value of (18)F-FDG PET-CT imaging in patients with primary extranodal lymphoma

To investigate the diagnostic value of (18)F-FDG PET-CT imaging in primary extranodal lymphoma. A retrospective analysis of 139 clinically suspected primary extranodal lymphoma patients examined by PET-CT and confirmed by biopsies was performed. Considering the pathological diagnosis as the gold standard, PET-CT imaging of all patients was compared with CT and PET to evaluate the efficacy of 18F-FDG PET-CT in detection of primary extranodal lymphoma. The maximal standardized uptake value (SUVmax) from primary extranodal lymphoma patients was compared, and the data were analyzed by χ² test. Of the total 139 analyzed cases, 128 patients were confirmed to have primary extranodal lymphoma. The sensitivity, specificity and positive rate of PET-CT were 82.8%, 81.8% and 82.7%, respectively, that of CT were 65.6%, 72.7% and 66.2%, and that of PET were 78.9%, 36.4% and 82.0%, respectively. The sensitivity and accuracy of PET-CT were better than that of CT (χ²=9.881, 10.006; P=0.003, 0.002). The specificity of PET-CT were better than that of PET (χ²=4.487, P=0.034). In the gastrointestinal lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=5.110, P=0.024). In the head and neck lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=5.278, P=0.022). In the diffuse large B-cell lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=8.711, P=0.003). The SUV max of mucosa-associated lymphoma was significantly different from that of diffuse large B-cell lymphoma and natural killer/T-cell lymphoma (7.4±4.6 vs 15.8±10.6, P=0.032; 7.4±4.6 vs 13.6±7.1, P=0.046), respectively. 18F-FDG PET-CT imaging is important in the diagnosis of primary extranodal lymphoma, but the differential diagnosis with other disease is important, and the result should be combined with multiple biopsies.

Comparing Respiratory Gated With Delayed Scans in the Detection of Colorectal Carcinoma Hepatic and Pulmonary Metastases With 18F-FDG PET-CT

In patients experiencing colorectal carcinoma, exhaustive analysis of indicates extent of hepatic and pulmonary surgery that prolongs survival of patients. To localize metastasis, we compared 2 F-FDG PET-CT imaging protocols, early respiratory gated scan, and delayed scan, to standard PET imaging procedure. SUVmax and lesion-to-healthy tissue ratio were measured in 60 pulmonary and 21 hepatic lesions by each of the 2 imaging protocols. In the liver, metastatic lesion-to-healthy tissue ratios significantly increased on delayed scans as compared with early scans (P < 0.001). Better ratios could not be obtained when using respiratory gated scans, whereas more lesions were detected on delayed scans. In the lungs, metastatic lesion- to-healthy tissue ratio increased significantly on delayed scans for largest lesions (P < 0.001). Ratios were not better when exploring smallest metastatic lesions or when using respiratory gated scans. Factors interfering with F-FDG PET-CT sensitivity are discussed, such as respiratory motion and high FDG physiological uptake in healthy liver parenchyma. Our studies indicate that routine acquisitions should use delayed hepatic scans for all patients referred for evaluation, recurrence check, or monitoring of colorectal adenocarcinoma. Delayed pulmonary scans are useful for the largest metastatic lesions and should be used in addition to early scan. In our experience, respiratory gated scans seem to be less convenient because of a low sensitivity in detection, as compared with the delayed technique; in addition, this technique is currently complicated by some technical issues, although these might be overcome with new gated protocols.

Can Initial (18)F-FDG PET-CT Imaging Give Information on Metastasis in Patients with Primary Renal Cell Carcinoma?

PurposeThe aim of this study was to investigate the relationship between the maximum standardized uptake values (SUVmax) of primary renal cancers with and without metastatic lesions, if any. We also studied the relationship between the size of primary renal cancers and their SUVmax, and tried to find a clinical value of 18F-FDG PET-CT for the initial evaluation of renal cell carcinoma (RCC).MethodsThe cases of 23 patients, 16 men and 7 women, who underwent PET-CT examination before operation were retrospectively reviewed. We measured the SUVmax of the primary renal cancers and those of any existing metastatic lesions, and the size of the primary renal cancers. We compared the SUVmax of primary RCCs with metastases and those without metastases, SUVmax of primary RCC and those of metastases, and studied the correlation between the size and SUVmax of primary RCCs.ResultsThe SUVmax of primary RCC of the 16 patients without metastasis ranged from 1.1 to 5.6 with a median value of 2.6. Those of the patients with metastasis ranged from 2.9 to 7.6 with a median of 5.0. The size of the all 23 primary renal cancers ranged from 1.7 cm to 13.5 cm, with a median of 4.5 cm, and their SUVmax ranged from 1.1 to 7.6, with a median of 2.9. There was a statistically significant difference between the SUVmax of the primary RCC with metastasis (5.3 ± 1.7) and those without metastasis (2.9 ± 1.0). There was a moderate positive correlation between the sizes and SUVmax of all 23 primary RCCs. However, there was no statistically significant correlation between the sizes and SUVmax of primary RCCs with metastatic lesions and the same for RCCs without metastasis. The cutoff value of SUVmax for predicting extra-renal lesion was 4.4 and that for size was 5.8 cm according to the receiver operating characteristic curves.ConclusionsThose who have primary RCC with high SUVmax are suggested to have a likelihood of metastasis. Also, there was a moderate trend of increasing value of SUVmax of primary RCC as their size increases. Physicians should beware of missing extra-renal lesions elsewhere.

Primary tumor SUVmax measured on (18)F-FDG PET-CT correlates with histologic grade and pathologic stage in non-small cell lung cancer

To assess the relationship between preoperative maximum standardized uptake value (SUVmax) measured on (18)F-FDG PET-CT and clinicopathologic parameters in patients with surgically resected non-small cell lung cancer (NSCLC). A total of 540 patients (348 men and 192 women, mean age 60 ± 10 years) with histologically proven non-small cell lung cancer, who had undergone both preoperative (18)F-FDG PET-CT imaging and curative surgery in our institution from October 2006 to January 2013, were analyzed retrospectively in this study. Primary tumor (18)F-FDG uptake, measured as SUVmax corrected for lean body mass, was compared among different variables and correlated with tumor size, histologic grade and postoperative pathologic TNM stage. Histologic grade was categorized into three degrees, where grade I represents highly, grade II moderately and grade III poorly differentiated. Large cell carcinomas were all assessed as poorly differentiated (grade III). Pathologic stage was assigned according to the seventh AJCC TNM staging system. There were 344 adenocarcinomas (AC, non- BAC type), 146 squamous cell carcinomas (SCC), 28 bronchioloalveolar carcinomas (BAC), 10 adenosquamous carcinomas (ASC) and 12 other type carcinomas (OTC, including 6 large cell carcinomas, 5 sarcomatoid carcinomas and 1 lymphoepitheloid carcinoma); the SUVmax in ascending order was BAC (1.3 ± 1.1), AC (5.1 ± 3.4), ASC (8.5 ± 2.8), SCC (9.9 ± 4.6) and OTC (10.9 ± 5.1), respectively. There were 76 grade I, 251 grade II and 213 grade III; the SUVmax in ascending order was grade I (2.4 ± 2.2), grade II(5.9 ± 3.9), grade III (8.4 ± 4.4), respectively, and significant difference was identified among grade I, grade II and grade III (all P < 0.01). The SUV max was positively correlated with tumor size (r = 0.564, P < 0.01), histologic grade (r = 0.492, P < 0.01), T stage (r = 0.306, P < 0.01), N stage (r = 0.368, P < 0.01), and TNM stage (r = 0.437, P < 0.01). The preoperative SUV max of the primary tumor differed significantly among histologic types in NSCLC. There were positive correlations between SUV max and tumor size, histologic grade and pathologic stage. Our findings may suggest that a high SUVmax could be used to identify a high-risk population who would benefit most from adjuvant therapies.

Prognostic value of dual-time-point 18F-FDG PET-CT imaging in patients with head and neck squamous cell carcinoma

The objective of this study was to investigate the independent prognostic value of dual-time-point (18)F-fluorodeoxyglucose ((18)F-FDG) PET-CT imaging in patients with head and neck squamous cell carcinoma (HNSCC). Patients referred to our department to undergo (18)F-FDG PET-CT for staging of HNSCC were prospectively included. Each patient was scanned using a Philips Gemini PET-CT system 1 h (early acquisition) and 2 h (delayed acquisition) after injection. An intratumoral retention index (RI) of (18)F-FDG was measured for each examination by the dual-time-point method. Event-free survival (EFS) and overall survival (OS) were determined by the Kaplan-Meier method and compared with the conventional maximum standardized uptake value (SUV(max)) at 60 min, SUV(max) at 120 min, and RI in univariate and multivariate analyses including the usual prognostic factors such as age, sex, primary site, SCC histologic grade, and American Joint Committee on Cancer stage (I, II, III, and IV). Sixty-six consecutive patients (60 men and six women; mean age=61 ± 9 years) were included in the study. In univariate analysis, besides age and stage, RI was predictive of EFS (P=0.01) but not of OS (P=0.1), whereas SUV(max) at 60 min was not predictive of EFS (P=0.18) or OS (P=0.08) and SUV(max) at 120 min was predictive of OS (P=0.02) but not of EFS (P=0.05). In multivariate analysis, RI persisted as an independent predictive factor for EFS (P=0.02) but not SUV(max) at 120 min for OS (P=0.12). Our results suggest an additional prognostic interest of RI measured by dual-time-point (18)F-FDG PET-CT, independent of usual prognostic factors, in patients with HNSCC.

Correlation of ¹⁸F-FDG uptake with tumor-proliferating antigen Ki-67 expression in aggressive lymphoma

To investigate the correlation between ¹⁸F-FDG uptake in positron emission tomography/computed tomography imaging and tumor-proliferating antigen Ki-67 expression in aggressive lymphoma. Data of ¹⁸F-FDG PET-CT imaging and immunohistochemical detection of Ki-67 expression of seventy-seven cases with initially diagnosed aggressive lymphoma were retrospectively analyzed. The intensity of ¹⁸F-FDG accumulation was determined by calculating the maximum standardized uptake value (SUVmax) and average standardized uptake value (SUVave). The average SUV at biopsy site (BxSUVave), SUVmax at biopsy site (BxSUVmax) and SUVmax at the highest tumor activity site of the body (BmSUVmax) were collected. The BmSUVmax, BxSUVmax, and BxSUVave were 13.4 ± 6.8, 11.9 ± 6.8 and 7.3 ± 4.4, respectively,and Ki-67 was (61.2 ± 20.4)% in the 77 aggressive lymphomas. The BmSUVmax was significantly higher than the BxSUVmax or BxSUVave (P < 0.05). The BmSUVmax, BxSUVmax and BxSUVave were positively correlated with the Ki-67 expression in aggressive lymphoma (P < 0.05). A positive correlation was revealed between the BxSUVmax and BmSUVmax (P < 0.05), and between the BxSUVmax and BxSUVave (P < 0.05). No significant correlation was found between the BmSUVmax or BxSUVmax and the Ki-67 in DLBCL (P > 0.05). A positive correlation was observed between the BmSUVmax or BxSUVmax and the Ki-67 expression in NK/T cell lymphoma (P < 0.05). The increasing trend of ¹⁸F-FDG uptake is correlated with the Ki-67 expression in aggressive lymphoma. The results of this study suggest that the metabolic information obtained by using BmSUVmax may help to compensate the limited sampling of histological examination at the biopsy site. Significant correlation in NK/T cell lymphoma suggests that the metabolic information from positron emission tomography-computed tomography may offer a useful parameter in the prognosis and management of this disease.