SUVmax Ratio Research Articles

The Value of Positron Emission Mammography (PEM) in Management of Breast Cancer

To determine the value of few key parameters measured from 3D-PEM breast images in breast cancer management. One hundred nine, pathology proven, female breast cancer patients with mean age of 66 ± 11 (ranging from 28 to 83) years underwent PEM imaging for surgical planning at our institute. Ten mCi of 18-flourodeoxy glucose (FDG) was administered intravenously. One hour post-injection, multiple tomographic sections of the right and left breast were obtained in medio-lateral, oblique and cranio-caudal (cc) positions. Retrospectively, lesion depth (using cc image), lesion size, lesion shape (ovoid, circular, irregular ovoid, irregular circular, ring-like, linear) and maximum standard uptake value (SUVmax) of FDG in lesion and normal fatty breast area was evaluated. The ratio of SUVmax of lesion to normal fatty breast area was computed. Whole body PET/CT FDG images were used for staging the breast cancer. Out of 109 patients 53.0% had left sided lesion and 47.0% were right sided. Seventy six percent of the patients had a single lesion and the remaining 24.0% had multiple lesions. The most common shape was found to be circular for 42.4% of the patients, 23.6% irregular circular, 21.2% irregular ovoid, 8.3% ovoid, 3.0% linear and 1.5% ring like. Less than 2.0% had a lesion depth of ≤ 0.7 cm. Remaining 98% had lesions at depths ranging from 0.9 cm to 10.8 cm with mean depth of 3.8 ±1.9 cm. All patients with lesions ≥ 0.7 cm were candidates for treatment with single lumen balloon catheter using Xoft E-brachytherapy system for accelerated partial breast irradiation (APBI). Patients with lesion depths ≤ 0.7 cm were candidates for multi-lumen balloon catheter. The average value for maximum PEM SUV (SUVmax) in the lesion was 1.49 ± 1.09 (ranging from0.46 to 7.48) and in normal fatty breast tissue was 0.25 ± 0.13(ranging from 0.07 to 0.90). The mean ratio of SUVmax of lesion to normal tissue was 6.35 ± 4.04 (ranging from 0.88 to 24.1). The number of metastatic lesions was determined from PET/CT images. Preliminary findings suggest a correlation of this ratio with staging of the breast cancer determined from whole body PET/CT scan of these patients. PEM imaging may provide valuable parameters such as accurate lesion depth measurement which in turn helps decipher the selection of single vs multi-lumen catheter for APBI. In addition to this the ratio of SUVmax may help predicting the stage and hence, prognosis and management of breast cancer.

Value of 18F-FDG PET/CT in the diagnosis of primary gastric cancer via stomach distension

ObjectiveTo clarify the usefulness of 18F-FDG PET/CT for detecting primary gastric cancer via gastric distention using a mixture of milk and Diatrizoate Meglumine. Materials and methodsA total of 68 patients (male: 47, female: 21; age: 41–87 years) suspected of gastric carcinoma underwent 18F-FDG PET/CT imaging. After whole-body PET/CT imaging in a fasting state, the patients drank a measured amount of milk with Diatrizoate Meglumine. Local gastric district PET/CT imaging was performed 30min later. The imaging was analyzed by semi-quantitative analysis, standardized uptake value (SUV) of the primary tumor was measured in a region of interest. The diagnosis results were confirmed by gastroscopy, pathology, and follow-up results. ResultsOf the 68 patients, 56 malignant gastric neoplasm patients (male: 37, female: 19) were conformed. The sensitivity, specificity, positive predictive value and negative predictive value of fasting whole-body PET/CT imaging for a primary malignant tumor were 92.9%, 75.0%, 94.5%, and 69.0%, respectively. The values for distension with a mixture of milk and Diatrizoate Meglumine were 91.1%, 91.7%, 98.1%, and 68.8%, respectively. The area under the curve was 0.919±0.033 and 0.883±0.066 for the diagnosis of gastric cancer with SUVmax in a fasting state and after intake of mixture respectively, the differences were not statistically significant (P=0.359). Using gastric distension with a mixture of milk and Diatrizoate Meglumine, the mean ratio of the lesion's SUVmax to the adjacent gastric wall SUVmax increased significantly from 3.30±3.05 to 13.50±15.05, which was statistically significant (P<0.001). Conclusions18F-FDG PET/CT imaging is highly accurate for the diagnosis of primary gastric carcinoma. Gastric distention can display the lesions more clearly, however, it cannot significantly improve diagnostic accuracy.

Evaluation of (18)F-FDG Uptake Pattern in Brown Adipose Tissue Over Extended Time Period as Assessed by Multiple Time Point (18)F-FDG-PET.

To study the (18)F-FDG uptake pattern in brown adipose tissue (BAT) over an extended time period, by multiple-time-point fluorodeoxyglucose positron emission tomography (FDG-PET) imaging. The primary objective for this kind of research was that it could form a basis and may have further implications for obesity research, metabolic diseases and for cachexia of both malignant and benign origin. A total of 12 patients who had undergone routine FDG-PET for disease evaluation and had demonstrated prominent BAT uptake in their baseline scans were selected. The patients with the diagnosis of neuroendocrine tumors were excluded. Maximum standardized uptake values (SUVmax) were calculated in the BAT of the supraclavicular and paravertebral areas of either side, and were analyzed separately to examine their behavior individually. Time activity curves (TACs) were generated for [A] BAT SUVmax values and [B] SUVmax ratio of BAT/lung (B/L SUVmax ratio) at various time points. Ten out of the 12 patients were imaged at four time points, and two patients were imaged for two time points. Amongst a total of n = 30 sites, 23 were imaged at four time points and seven were imaged at two time points. Seventeen out of 30 area sites (56.67%) demonstrated a peak value at 60 min and a falling trend of SUVmax afterwards; the remaining showed a peak uptake value between 85 and 300min after the first scan (i.e. 145-360min after injection), and falling values thereafter. With regard to the B/L SUVmax ratio, ten out of 30 sites (33.33%) demonstrated peak uptake at 60 min, and the remaining showed a rise, with peak uptake at times between 85 and 300min after the first scan (i.e. 145-360min after injection) and falling values thereafter. No additional area of BAT uptake was observed over the extended time period in this study. Wide variability was observed in the BAT FDG uptake over an extended period of time. Nearly half of the sites demonstrated an increase in FDG uptake until 360min (i.e. 6h) after injection, while the remaining half showed peak uptake at 1h and subsequent fall of uptake. In the future, it will be worthwhile to study whether there exists any difference in time course of FDG uptake in brown fat between patients with cancer and those scanned for benign etiologies, or between obese and non-obese individuals.

Dual-Tracer PET/CT in Renal Angiomyolipoma and Subtypes of Renal Cell Carcinoma

We studied the metabolic characteristics of RCC subtypes and angiomyolipoma with 18F-FDG and 11C-acetate PET/CT. Fifty-eight patients with both baseline CT and dual-tracer PET/CT were recruited: 10 angiomyolipoma (16 lesions) and 48 RCC (50 lesions). Each lesion was assessed for SUVmax ratio (lesion-to-normal kidney) on 11C-acetate/18F-FDG PET and attenuation density on CT. Receiver operating characteristic (ROC) curve was analyzed to define the threshold of 11C-acetate SUVmax ratio for differentiating angiomyolipoma from RCC. Thirty-nine RCC patients were selected for 3-year disease-free survival analysis. All angiomyolipoma showed negative 18F-FDG but markedly increased 11C-acetate metabolism, significantly higher than RCC (11C-acetate SUVmax ratio = 4.11 ± 0.53 vs 2.00 ± 0.71; P < 0.05). 11C-acetate SUVmax ratio = 3.71 could differentiate angiomyolipoma including "fat-poor angiomyolipoma" (n = 10) from RCC with sensitivity of 93.8% (15/16) and specificity of 98.0% (49/50). Different RCC subtypes/grades (25 low- and 11 high-grade clear cell [CC], 7 chromophobe, 4 papillary, and 1 collecting duct) were found to have different dual-tracer metabolic pattern (P < 0.05), with overall RCC detection sensitivity of 90% (45/50). All chromophobe RCC were avid only for C-acetate but not 18F-FDG, whereas papillary RCC were primarily the opposite. RCC-CC showed variable dual-tracer uptake: high-grade more avid for F-FDG, low-grade more for 11C-acetate. Four RCC cases negative by dual-tracers were of low-grade RCC-CC. "Primary RCC being 18F-FDG-avid" was the only independent predictor of RCC recurrence in 3 years (P < 0.05), with a median disease-free survival of 22 months. 11C-acetate PET/CT helps in differentiating "fat-poor angiomyolipoma" from RCC. Dual-tracer PET/CT has value in diagnosis of RCC subtypes and predicting survival.

Positron emission tomography in bronchioloalveolar carcinoma of the lung

ObjectivesThis study assessed the maximum standard uptake value of positron emission tomography–computed tomography in patients of pulmonary adenocarcinoma with bronchioloalveolar carcinoma features and whether SUVmax correlates with pathological status, lymph node metastasis, and prognosis. MethodsWe retrospectively reviewed 674 patients diagnosed with non-small-cell lung cancer between January 2002 and June 2009. Patients with clinical stage I–II disease underwent a preoperative PET–CT scan followed by anatomic resection. We reviewed the clinical features of 209 patients with an average follow-up of 87 months. ResultsWe analyzed clinical variables for 40 patients with BAC features and 169 patients without BAC features. Age, sex, location, and number of dissected lymph nodes, carcinoembryonic antigen level, and lymphovascular invasion had no difference between the two groups. Compared with non-BAC patients, patients with BAC features had a lower SUVmax (2.51 ± 2.02 vs 4.98 ± 4.03, p < 0.001), lower ratio of SUVmax (1.10 ± 0.34 vs 1.22 ± 0.27, p = 0.014), better tumor differentiation (p < 0.001), and smaller tumor size (2.30 ± 1.41 vs 2.97 ± 1.71, p < 0.03). The negative prediction rate was 87.08% for N2 and 80.80% for N1 disease. All patients in the BAC group were alive after the operation. The five-year survival rate of patients without BAC features was 71.2%. ConclusionsPreoperative SUVmax of PET–CT was more accurate at predicting negative N2 than N1 disease. BAC is associated with markedly better prognosis compared with invasive adenocarcinoma and may be cured with surgical resection Aggressive surgical resection is recommended even for patients with false-negative N2 disease.

Ratio of Positron Emission Tomography Uptake to Tumor Size in Surgically Resected Non–Small Cell Lung Cancer

In patients with non-small cell lung cancer (NSCLC), previous studies have shown a prognostic benefit of maximum standardized uptake (SUV(max)) values on positron emission tomography (PET). Because tumor size is also prognostic and is associated with SUV(max), we sought to better characterize their relationship. We hypothesize that the ratio of SUV(max) to tumor size is a clinically useful measurement. A retrospective review was performed for patients (tumors ≥ 1 cm) undergoing resection of NSCLC. Patients were placed into quartiles (SUV(max) and SUV(max) to tumor size ratio) and compared for clinical and pathologic factors. Predictors of SUV(max) and SUV(max) to tumor size ratio on survival were evaluated. Among 530 patients, increasing tumor size (odds ratio [OR], 2.04; confidence interval [CI], 1.68-2.47; p < 0.001) was an independent predictor of higher SUV(max). Patients in quartiles by the ratio of SUV(max) to tumor size demonstrated no significant difference in median tumor size. Those patients with the highest ratios (QR4, 3.21-27.5) more frequently had poorly differentiated tumors (51%; p < 0.001), were likely to have lymph node metastases (30%; p < 0.001), and had poor 3-year disease-free survival (DFS) (58%; p = 0.013). On multivariate analysis, as a continuous variable SUV(max) to tumor size ratio was a stronger independent predictor of survival than SUV(max) alone (hazard ratio [HR], 1.06; CI, 1.00-1.13 versus HR, 1.02; CI, 0.99-1.06). Using cutpoint analysis, a high SUV(max) to tumor size ratio was also a stronger predictor of survival than was high SUV(max) alone, particularly for tumors 1-3 cm (HR, 1.53; CI, 0.93-2.53 versus HR, 1.15; CI, 0.69-1.93). The ratio of SUV(max) to tumor size may be a more important indicator of prognosis than SUV(max) alone in patients with NSCLC. In particular, the use of the ratio may be appropriate for identifying patients with small tumors who are at high risk for lymph node metastases and poor survival.

Differentiation of Newly Diagnosed Glioblastoma Multiforme and Intracranial Diffuse Large B-cell Lymphoma Using 11C-Methionine and 18F-FDG PET

The aim of our study was to examine the usefulness of PET with C-methionine (MET) and F-fluorodeoxyglucose (FDG) in the differentiation of glioblastoma multiforme (GBM) and intracranial diffuse large B-cell lymphoma (DLBCL). We evaluated 22 patients retrospectively with an enhancing brain tumor on MRI, including 15 GBM and 7 DLBCL, which was confirmed by histopathology. Dynamic PET scans with MET and FDG were performed for preoperative differential diagnosis. We assessed the images qualitatively and quantitatively. In quantitative assessment, the SUVmax was used on FDG PET and both late and early phases on MET PET. In addition, the ratio of SUVmax in the late and early phases on MET-PET was evaluated (ΔSUVmax). SUVmax on FDG PET of DLBCL was significantly higher than that of GBM. Setting an SUVmax of 12.0 as the cutoff for differentiating DLBCL from GBM, 1 GBM and 1 DLBCL were found to be false-positive and false-negative, respectively.SUVmax in the late and early phases of MET-PET was not significantly different between DLBCL and GBM; however, we also found significant differences in ΔSUVmax on MET-PET. Using ΔSUVmax 1.17 as the cutoff, we could differentiate DLBCL from GBM completely. In the present study, ΔSUVmax on MET-PET was slightly superior to SUVmax on FDG PET. Both SUVmax on FDG PET and ΔSUVmax on MET-PET were considered to be good diagnostic tests when encountering difficulties in this differential diagnosis.

Comparison of 18F-Fluorodeoxyglucose and 18F-Fluorothymidine PET in Differentiating Radiation Necrosis From Recurrent Glioma

The objective was to compare F-fluorodeoxyglucose (FDG) and F-fluorothymidine (FLT) PET in differentiating radiation necrosis from recurrent glioma. Visual and quantitative analyses were derived from static FDG PET and static and dynamic FLT PET in 15 patients with suspected recurrence of treated grade 2 glioma or worse with a new focus of Gd contrast enhancement on MRI. For FDG PET, SUVmax and the ratio of lesion SUVmax to the SUVmean of contralateral white matter were measured. For FLT PET, SUVmax and Patlak-derived metabolic flux parameter Kimax were measured for the same locus. A 5-point visual confidence scale was applied to FDG PET and FLT PET. Receiver operating curve analysis was applied to visual and quantitative results. Differences between recurrent tumor and radiation necrosis were tested by Kruskal-Wallis analysis. On the basis of follow-up Gd-enhanced MRI, lesion-specific recurrent tumor was defined as a definitive increase in size of the lesion, and radiation necrosis was defined as stability or regression. For FDG SUVmax, the FDG ratio of lesion-white matter, and FLT Kimax, there was a significant difference between mean values for recurrent tumor and radiation necrosis. Recurrent tumor was best identified by the FDG ratio of lesion-contralateral normal white matter (area under the curve of 0.98, confidence interval of 0.91 to 1.00, sensitivity of 100%, and specificity of 75% for an optimized cutoff value of 1.82). Both quantitative and visual determinations allow accurate differentiation between recurrent glioma and radiation necrosis by both FDG and FLT PET. In this small series, FLT PET offers no advantage over FDG PET.

The role of tumor SUVmax/lymph node SUVmax ratio viewed on PET-CT in the detection of mediastinal metastasis in patients with lung cancer

The role of tumor SUVmax/lymph node SUVmax ratio viewed on PET-CT in the detection of mediastinal metastasis in patients with lung cancer

Comparison of 18F-fluoro-deoxy-glucose, 18F-fluoro-methyl-choline, and 18F-DPA714 for positron-emission tomography imaging of leukocyte accumulation in the aortic wall of experimental abdominal aneurysms

Abdominal aortic aneurysm (AAA) is a frequent form of atherothrombotic disease, whose natural history is to enlarge and rupture. Indicators other than AAA diameter would be useful for preventive surgery decision-making, including positron-emission tomography (PET) methods permitting visualization of aortic wall leukocyte activation relevant to prognostic AAA evaluation. In this study, we compare three PET tracers of activated leukocytes, 18F-fluoro-deoxy-glucose (FDG), 18F-fluoro-methyl-choline (FCH), and 18F-DPA714 (a peripheral benzodiazepine receptor antagonist) for in vivo PET quantification of aortic wall inflammation in rat experimental AAAs, in correlation with histopathological studies of lesions. AAAs were induced by orthotopic implantation of decellularized guinea pig abdominal aorta in 46 Lewis rats. FDG-PET (n = 20), FCH-PET (n = 8), or both (n = 12) were performed 2 weeks to 4 months after the graft, 1 hour after tracer injection (30 MBq). Six rats (one of which had FDG-PET) underwent 18F-DPA714-PET. Rats were sacrificed after imaging; AAAs and normal thoracic aortas were cut into axial sections for quantitative autoradiography and histologic studies, including ED1 (macrophages) and CD8 T lymphocyte immunostaining. Ex vivo staining of AAAs and thoracic aortas with 18F-DPA714 and unlabeled competitors was performed. AAAs developed in 35 out of 46 cases. FCH uptake in AAAs was lower than that of FDG in all cases on imaging, with lower AAA-to-background maximal standardized uptake value (SUV(max)) ratios (1.78 ± 0.40 vs 2.71 ± 0.54; P < .01 for SUV(max) ratios), and lower AAA-to-normal aorta activity ratios on autoradiography (3.52 ± 1.26 vs 8.55 ± 4.23; P < .005). FDG AAA-to-background SUV(max) ratios correlated with the intensity of CD8 + ED1 staining (r = .76; P < .03). FCH AAA-to-background SUV(max) ratios correlated with the intensity of ED1 staining (r = .80; P < .03). 18F-DPA714 uptake was similar in AAAs and in normal aortas, both in vivo and ex vivo. In rat experimental AAA, characterized by an important aortic wall leukocytes activity, FDG-PET showed higher sensitivity than FCH-PET and 18F-DPA714-PET to detect activated leukocytes. This enhances potential interest of this tracer for prognostic evaluation of AAA in patients.

Étude rétrospective des conséquences de l’administration d’une préparation de FDG contenant de 5 % à 10 % de fluorure (18F) libre sur l’imagerie TEP/TDM de l’os sain et des foyers osseux pathologiques. Comparaison avec un groupe apparié de patients ayant reçu une préparation de FDG contenant moins de 5 % de fluorure (18F) libre

Following administration in January 2010 of a commercial preparation of FDG containing between 5 and 10% of fluoride (18F), our aim was to evaluate by means of a retrospective study the consequences of this content of free 18F on the visual and semi-quantitative approaches of the skeletal uptake on PET/CT. MethodsTwo groups of 30 patients (princeps and control) were matched for pathology, age, sex and glycaemia. The group “princeps” received the FDG preparation containing more than 5% of fluoride (18F). All examinations were done according to the standard protocol of FDG PET/CT. The SUVmax was determined in six regions of interest (ROI) in visually normal bone. For pathologic foci, we calculated a ratio of SUVmax between the focus and healthy bone (T/NTR). ResultsThe analysis of normal bone showed, for the spine, a significant difference in SUVmax between the two groups and a significant correlation with the time elapsed between FDG preparation and injection. Concerning the pathologic foci, the T/NTR of two groups were significantly different (P=0.04). ConclusionWe observed a slight increase of the SUVmax in the healthy spine of patients who received more than 5% of fluoride (18F), explained in part by a longer delay before imaging. The pathologic foci showed a T/NTR lower in the group princeps, however metastases were detected in both groups. Thus, a preparation of FDG close to the end of its shelf life can be used without real consequences for the quality of images for a given patient; in contrast, an accurate quantification of the FDG uptake in the spine requires a minimal proportion of fluoride (18F).

Functional imaging of HER2-positive metastatic breast cancer using 64Cu DOTA-trastuzumab positron emission tomography (PET).

639 Background: We are developing 64Cu-labeled trastuzumab (tras) as a PET imaging agent for women with HER2+ beast cancer. To maximize image quality and minimize HER2 uptake in normal tissues, we pre-administered 2 different doses of cold tras prior to injection of the imaging agent. Methods: Pts with advanced breast cancer were eligible if they had bx confirmed HER2 + disease, had not received anti-HER therapy for 6 mos. and had &gt; 1 non-hepatic site of metastasis &gt; 2 cm outside the biopsy site. All un-derwent staging FDG/PET and bone scan. Prior to injection of 64Cu-tras, pts. received 5 or 50 mg (2 and 4 pts) of cold tras. PET-CT was obtained at 21-25 h and 47-48 h over fields of view chosen in reference to 18F-FDG scans. Uptake in organs and lesions were measured in terms of body wt-normalized SUV. Lesions with intensity &gt; adjacent tissue were considered positive on PET. The number of metastatic sites identified on 64Cu-tras/PET was compared to the number on FDG/PET. Image quality was assessed according to differences between the 2 pretreatment doses. Results: Six pts have been imaged. Tras dose had a marked effect on liver uptake of64Cu [SUV = 23±3 (mean±sd) and 6.3±0.6 for 5 and 50 mg tras, respectively; P &lt; 0.05]. 72 CT+ lesions (32 bone, 28 nodal, 9 liver, 2 breast, 1 lung) were included in D1 and/or D2 scans. Of these, 66 of 72 (92%), 48 of 63 (76%) and 36 of 44 (82%) were detected on FDG, D1 and D2 scans, respectively. Lesion SUVmax was 9±5 (n=37, range 3-23) on D1 and 11±6 (n=27, range 1-29) on Day 2. 64Cu-tras-to-FDG SUVmax ratios were 1.0±0.8 (range 0.2-4.3) and 1.3±1.1 (range 0.2-3.5) for D 1 and 2. Lesion 64Cuuptake trendedliver &gt; bone &gt; nodes. Conclusions: 64Cu-tras/PET visualizes HER2+ lesions in bone, liver and, to a lesser degree, lymph nodes. Pre-administration of cold tras improves the quality of tras/PET, especially of intrahepatic lesions. In the next phase of study we will perform 64Cu-tras/PET in pts with HER2 1+ and 2+ disease.

Relation Between Popliteal-Tibial Artery Atherosclerosis and Global Glycolytic Metabolism in the Affected Diabetic Foot

We evaluated the extent and the degree of active atherosclerosis in the popliteal-tibial arteries by quantitative techniques using [(18)F]-2-fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET). An effort was made to determine whether there was a positive correlation between the level of ongoing atherosclerosis and subsequent chronic ischemia in the diabetic foot. A total of 115 diabetic patients were enrolled in this prospective research study and underwent lower-extremity FDG-PET and magnetic resonance imaging. We selected 36 diabetic patients with complicated diabetic foot for this analysis (11 men, 25 women; mean age, 59.5 years; age range, 36-85 years). Ten nondiabetic control participants (6 men, 4 women; mean age, 59.7 years; age range, 27-88 years) were also included for comparison. Only patients with blood glucose levels less than 200 mg/100 mL were enrolled in this study. The metabolic volumetric product (MVP), for each patient was calculated multiplying foot average maximum standard uptake value (SUV(max)) by foot volume. Pearson correlation analysis between foot mean SUV(max) alone and the degree of atherosclerosis and between the foot MVP and the degree of atherosclerosis was performed as measured by FDG-PET. A t test was used to assess for significant differences in foot SUV(max) and foot MVP among varying degrees of atherosclerosis, using P < .05 as the criterion for statistical significance. Foot SUV(max) significantly correlated (P < .05) with the ratio of popliteal-tibial artery SUV(max) to background SUV (Pearson correlation coefficient = 0.49). Foot MVP was also significantly correlated (P < .05) with the ratio of popliteal-tibial artery SUV(max) to background SUV (Pearson correlation coefficient = 0.69). Using FDG-PET, one may be able to detect and quantify the degree of increased metabolic activity of early active atherosclerosis and the associated chronic tissue ischemic effects at the regional level and globally throughout the whole body during the asymptomatic phase of disease.

Usefulness of F-18 FDG PET/CT in the Evaluation of Early Treatment Response After Interventional Therapy for Hepatocellular Carcinoma

This retrospective study investigated the usefulness of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) after interventional therapy for hepatocellular carcinoma (HCC). Between March 2007 and November 2010, 31 patients (24 men, 7 women; mean age, 61.8 ± 11.0years) with 45 lesions underwent PET/CT within 1month after interventional therapy for HCC. Twenty-six patients with 40 lesions underwent transcatheter arterial chemoembolization (TACE), two patients with 2 lesions underwent radiofrequency ablation (RFA), and three patients with 3 lesions underwent percutaneous ethanol injection therapy (PEIT). Patients with a history of previous interventional therapy were excluded. Visual analysis was graded as positive when FDG was observed as an eccentric, nodular, or infiltrative pattern, and negative in case of isometabolic, hypometabolic, or rim-shaped uptake. For quantitative analysis, the standardized uptake value (SUV) was measured by region of interest technique. Maximum SUV (SUVmax) was assessed, and the ratio of SUVmax of tumor to mean SUV of normal liver (TNR) was calculated. The patients were divided into two groups, with and without residual tumor, based on 6-month clinical follow-up with serum alpha-fetoprotein and contrast-enhanced abdominal CT. Of the 45 lesions, 24 were classified in the residual tumor group and the other 21 lesions in the no residual tumor group. No residual tumor was detected after RFA or PEIT. By visual analysis, the respective values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.5, 71.4, 77.8, 83.3, and 80.0%. However, there were no significant differences in the SUVmax and TNR between the two groups. It is suggested that FDG PET/CT may play a role in the evaluation of early treatment response after interventional therapy for HCC. The results indicate that FDG PET/CT visual analysis may be more useful than quantitative analysis. Further prospective studies with a large number of patients and established protocol are needed to substantiate our results.

Characterization of adrenal metastatic cancer using FDG PET/CT

The adrenal gland is a common location for metastasis from a primary tumor in another organ. This study evaluated the properties of adrenal lesions in cancer and non-cancer patients and investigated what variables may help predict adrenal metastasis. This retrospective study used 18fluorodeoxyglucose PET/CT on 371 patients with adrenal lesions (N = 260 with a primary tumor and N= 111 with an unknown primary tumor). Parameters such as the presence of a tumor, nodule, enlarged adrenal, maximum standardized uptake (SUVmax ratio) were evaluated. Univariate and multivariate analysis were used to identify variables that may predict risk of adrenal metastasis. Subjects with adrenal metastasis versus those without had a higher frequency of primary lung tumors (53.7% versus 28.6%, respectively; P≤ 0.001) but a lower frequency of gastrointestinal cancer (9.3% versus 20.4%, respectively; P = 0.014). The frequency of other abnormalities including nodules and enlarged adrenals were similar between cancer and non-cancer subjects. A higher proportion of subjects with adrenal metastasis regardless whether the primary tumor site in the lung, gastrointestinal track, or liver had SUVmax ratio > 2.5 versus those with no adrenal metastasis. In this cohort of subjects, the greatest proportion of subjects with adrenal metastasis was those with primary lung cancer. Univariate and multivariate analysis indicated that age, SUVmax ratio, and the presence of metastasis in multiple organs were independent variables for having adrenal metastasis. In this study, FDG PET/CT was useful in characterizing adrenal lesions including determining whether they were benign or malignant. This technology allowed us to identify characteristics that may useful in predicting adrenal metastasis and cancer severity.

Are Ratio of Lymph Node to Primary Focus SUV-max and PET/CT 18FDG Standard Uptake Value of Lymph Nodes Meaningful in Staging Non-Small Cell Lung Cancer?

Surgical treatment for mediastinal lymph node involvement in non-small cell lung cancer (NSCLC) will not have positive impact on survival. The present study aimed at investigating the role of positron emission tomography/computerized tomography (PET/CT) in staging NSCLC. Ninety-nine patients with maximal standard mediastinal lymph node involvement value (SUVmax) of 2.5 or more on PET/CT scanning were included in this study. All patients underwent invasive staging or pathological staging with direct thoracotomy. Relationship between lymph node SUVmax and lymph node/primary mass SUVmax ratio and presence of lymph node metastasis was investigated. Mean SUVmax ratio was 3.87 in the group with positive mediastinal lymph node on PET/CT but pathologically benign lymph nodes whereas it was 5.69 in those with pathologically malignant lymph nodes. Although there was a numeric difference between two groups, the difference was statistically insignificant (p= 0.65). Lymph node/mass SUVmax ratio was 0.49 in the patients with positive lymph nodes on PET/CT and benign pathology whereas it was 0.65 in those with malignant pathology and the difference between them was found to be not significant (p= 0.61). It was observed, however, that as SUVmax ratio increased, possibility of detecting malignant lymph node raised. Rate of malignancy was 52.38% in the group with SUVmax ratio of 0.1 to 0.3 whereas it was 91.66% in those with SUVmax ratio of 1 or greater. No significant relationship was found between lymph node SUVmax rate and presence of metastatic lymph node. We believe that more multi-center studies are needed with more patients.

Evaluation of the Sensitivity and Specificity of11C-Metomidate Positron Emission Tomography (PET)-CT for Lateralizing Aldosterone Secretion by Conn's Adenomas

Identification of unilateral aldosterone-producing (Conn's) adenomas has traditionally required lateralization by the invasive and technically difficult procedure of adrenal vein sampling (AVS). (11)C-metomidate, a potent inhibitor of adrenal steroidogenic enzymes, is a positron emission tomography (PET) radiotracer that is selectively accumulated by Conn's adenomas. The objective of the study was to compare the sensitivity and specificity of (11)C-metomidate PET-computed tomography (CT) against the current gold standard of AVS. The design of the study was within-patient comparison of diagnostic techniques. The study was conducted at a single center-university teaching hospital. Thirty-nine patients with primary hyperaldosteronism (PHA) and five with nonfunctioning adenomas (incidentalomas) participated in the study. The first six PHA patients were studied on three occasions to determine whether steroid pretreatment reduced (11)C-metomidate uptake by normal adrenal. Subsequent patients received dexamethasone for 3 d prior to injection of (11)C-metomidate 150-500 MBq. Maximum standardized uptake values (SUV(max)) over regions of interest determined from 35-45 min after injection were measured. Dexamethasone increased tumor to normal adrenal SUV(max) ratio by 25.6 ± 5.0% (P < 0.01). PET-CT visualized subcentimeter adenomas and distinguished hot from cold adenomas within a gland. In 25 patients with PHA and AVS lateralization to the side of an adenoma, SUV(max) over tumor (mean ± sem) of 21.7 ± 1.6 was greater than over normal adrenal, 13.8 ± 0.6 (P = 0.00003); this difference was absent in 10 patients without lateralization on AVS (P = 0.28) and in four of five incidentalomas. On receiver-operator characteristics analysis, an SUV(max) ratio of 1.25:1 provided a specificity of 87% [95% confidence interval (69, 104)] and sensitivity of 76% (59, 93); in tumors with SUV(max) greater than 17, the specificity rose to 100%. (11)C-metomidate PET-CT is a sensitive and specific noninvasive alternative to AVS in the management of PHA.

18F-FluoroDeoxyGlucose Uptake of Bone and Soft Tissue Sarcomas in Pediatric Patients

A high 18F-fluorodeoxyglucose (FDG) uptake by positron emission tomography/computed tomography (PET/CT) imaging in sarcomas of adults has been reported. The current study aimed at defining the degree of 18F-FDG uptake of pediatric sarcomas. This retrospective study included 29 patients (23 males, 6 females; mean age 14 ± 5 years) with soft tissue (n = 9) or bone (n = 20) sarcomas. Twenty-two patients (76%) underwent 18F-FDG PET/CT and 7 (24%) had dedicated 18F-FDG PET studies. Tumor 18F-FDG uptake was quantified by standard uptake value (SUV)max and tumor-to-liver ratios (SUV ratios; tumor SUVmax/liver SUVmean). Tumor SUVmax and SUV ratios were correlated with tumor Ki-67 expression. SUVmax ranged from 1.4 to 24 g/mL (median 2.5 g/mL) in soft tissue sarcomas and 1.6 to 20.4 g/mL (median 6.9 g/mL) in bone sarcomas (P = .03), and from 1.6 to 9.2 g/mL (median 3.9 g/mL) and 3.5 to 20.4 g/mL (median 12 g/mL) in Ewing sarcoma and osteosarcoma, respectively (P = .009). Tumor SUV ratios ranged from 0.8 to 8.7 (median 1.9) in soft tissue sarcomas and 1.4 to 8.9 (median 3.8) in bone sarcomas (P = .08). Ewing sarcoma had a significantly lower tumor SUV ratio than osteosarcoma (P = .01). Ki-67 expression correlated significantly with the 18F-FDG uptake in bone but not in soft tissue sarcomas. All sarcomas were visualized by 18F-FDG PET/CT imaging. A higher 18F-FDG uptake was observed in osteosarcoma than in Ewing and soft tissue sarcomas. The results of this study suggest that the degree of tumor 18F-FDG uptake is sufficient to allow for monitoring of therapeutic responses in pediatric sarcomas.

Significance of SUV on Follow-up F-18 FDG PET at the Anastomotic Site of Gastroduodenostomy after Distal Subtotal Gastrectomy in Patients with Gastric Cancer.

The aim of this study was to characterize the patterns of fluorodeoxyglucose (FDG) uptake on F-18 FDG positron emission tomography/computed tomography (FDG PET/CT) at the anastomotic site of gastroduodenostomy after distal subtotal gastrectomy in patients with gastric cancer. From May 2007 to May 2010, two or more follow-up measurements using FDG PET/CT scans were done for 19 patients (11 men, 8 women; mean age, 62.0 ± 10.3years) who underwent distal subtotal gastrectomy with gastroduodenostomy between February 2006 and March 2008 for detecting gastric cancer recurrence at our medical center. The FDG PET/CT images were retrospectively reviewed. Patients with local recurrence, regional nodal metastasis or distant metastasis on follow-up studies were excluded. CT and endoscopy were done within 1month before or after the FDG PET/CT scan. Eight patients had two follow-ups of FDG PET/CT, and 11 patients had three follow-ups. The mean interval between surgery and the first follow-up FDG PET/CT was 12.9 ± 0.8months (n = 19); between the first and second it was 12.3 ± 1.0months (n = 19); between the second and third it was 11.6 ± 0.7months (n = 11). The F-18 FDG uptakes at the anastomotic site and fundus in the remnant stomach were measured by maximum standardized uptake value (SUVmax) using a region of interest technique. The SUVmax at the anastomotic site was significantly higher than that of the fundus on all series of first, second and third follow-up studies (3.3 ± 1.1 vs. 2.1 ± 0.7, p < 0.001: 3.1 ± 0.9 vs. 2.2 ± 0.7, p = 0.001: 3.0 ± 0.6 vs. 2.1 ± 0.7, p = 0.006, respectively). The SUVmax for the anastomotic site and fundus, and SUVmax ratio for the anastomotic site over the fundus were not significantly different throughout the series. The SUVmax at the anastomotic site is significantly higher than that of the fundus and does not decrease significantly over time. Therefore, the local recurrence of gastric cancer after surgery could not be definitely differentiated from physiologic uptake or postoperative inflammatory change.

Contribution of PET/CT to Prediction of Outcome in Children and Young Adults with Rhabdomyosarcoma

The purpose of this retrospective study was to evaluate the role of (18)F-FDG PET or PET/CT in the prediction of patient outcome in children and young adults affected by rhabdomyosarcoma. Forty-one patients with histology-proven rhabdomyosarcoma who underwent PET or PET/CT were identified (age range, 1-20 y; mean age ± SD, 9.9 ± 5.8 y). Tumor maximum standardized uptake value (SUV(max)) and visually rated metabolic activity, as well as the presence of metabolically active lymph nodes and distant metastases, were compared with event-free and overall survival. Multivariate Cox regression analyses were performed to compare the prediction of outcome according to metabolic tumor intensity in relation to established prognostic factors. Kaplan-Meier analyses revealed a significantly shorter overall survival in primary tumors visually rated as highly metabolically active or with a ratio of SUV(max) to SUV of the liver above 4.6. In addition, metabolically active lymph node and distant site involvement was indicative of significantly lower survival rates. On multivariate Cox regression analysis, the impact of intensity or SUV(max) of the primary tumor on outcome failed to attain significance, although PET performed better than some of the prognostic factors established in larger patient groups (P = 0.081). (18)F-FDG PET/CT is a valuable tool for initial staging in children affected by rhabdomyosarcoma. (18)F-FDG PET/CT may be an additional predictor of outcome and may be used to refine risk-adapted therapy. PET performed better than some established risk factors. The borderline significance level of primary tumor metabolism in multivariate testing may be an effect of the limited sample size. Further prospective evaluations are warranted.