Levels Of FDG Uptake Research Articles

FDG uptake at the bronchial stump after curative lobectomy for non-small cell lung cancer.

Focal areas of FDG uptake may occur at the bronchial stump following curative lobectomy for non-small-cell lung carcinoma (NSCLC), even in the absence of suspicious CT changes. The purpose of our study was to investigate the significance of such PET/CT findings. FDG-PET/CT scans performed in 54 patients after lobectomy for NSCLC were reviewed. The presence of focal areas of FDG uptake at the bronchial stump, associated CT abnormalities, SUVmax, and normalized SUV (SUVnorm = SUVmax/mean liver SUV) were recorded. Final diagnosis was based on biopsy or imaging follow-up. Focal areas of FDG uptake at the bronchial stump were detected in 30 patients (56 %). Mean SUVmax was 4.0 ± 1.9 (range; 2.2-12.1) and mean SUVnorm was 1.8 ± 0.8 (range; 0.9-4.5). Biopsy showed recurrence in two patients. In these patients, SUVnorm was respectively 4.4 and 4.5 (with SUVmax of 8.8 and 12.1), whereas SUVnorm was lower than 4.0 in those without recurrence, with mean SUVnorm of 1.6 ± 0.5 (range; 0.9-3.4) and mean SUVmax of 3.6 ± 0.9 (range; 2.2-5.8). The CT component of the PET/CT revealed ill-defined peribronchial soft tissue opacity only in both patients with recurrence. FDG uptake at the bronchial stump is a frequent finding after pulmonary lobectomy. Moderate levels of FDG uptake (i.e., SUVnorm < 4.0) without corresponding abnormal CT findings might be a dual criterion for diagnosing benign post-surgical changes.

Is there any correlation between levels of serum ostepontin, CEA, and FDG uptake in lung cancer patients with bone metastasis?

In this study, an evaluation was made of the relationship between the serum levels of carcinoembryonic antigen (CEA), osteopontin (OPN), and the semi-quantitative parameters of 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in lung cancer patients with bone metastasis. The evaluation included 42 non-small cell lung cancer (NSCLC) and 31 small cell lung cancer (SCLC) patients who were referred to our institution for staging by (18)F-FDG PET/CT. The biochemical parameters measured included CEA and OPN serum levels. Serum levels of OPN in NSCLC patients with and without bone metastasis were 21.20±4.97 ng/ml and 13.33±4.53 ng/ml, respectively (p<0.05). In SCLC patients with and without bone metastasis serum OPN levels were 23.95±4.78 ng/ml and 17.30±3.09 ng/ml, respectively (p<0.05). Serum levels of CEA in NSCLC patients with and without bone metastasis were 33.79±6.49 ng/ml and 11.74±2.96 ng/ml, respectively (p<0.05). In SCLC patients with and without bone metastasis serum levels of CEA were 28.93±4.59 ng/ml and 13.88±4.47 ng/ml, respectively (p<0.05). There were no correlations between primary tumor SUVmax, and serum levels of CEA and OPN. Bone metastasis can be detected in patients with lung cancer by measuring CEA and OPN levels. Increased levels of CEA and OPN levels may be considered an early warning sign in patients needing accurate imaging, as they are at higher risk of bone metastasis.

The Diagnostic Performance of FDG PET/CT for Recurrent Gastric Cancer Is Significantly Affected by Primary Tumor FDG Uptake Level

Introduction: The outcome of advanced gastric cancer remains poor, and early detection of recurrence is important. FDG PET/CT is known to be useful in detection of recurrent gastric cancer, but the specific indication for surveillance with PET/CT in gastric cancer following curative resection remains unclarified to date. In this study, we evaluated the relation between FDG uptake of primary tumor and the patterns of recurrent disease in advanced gastric cancer. And we investigated whether FDG-avid primary tumors are associated with improved performance of surveillance PET/CT for detecting recurrent gastric cancer. Methods: Subjects were 372 patients (mean age 57.3 ± 11.5 y, male 254) with advanced gastric cancer who underwent curative surgery. All subjects had FDG PET/CT for initial staging and for recurrence surveillance after surgery. Primary tumors were classified as FDG-avid if they displayed focal uptake with SUVmax ≥ 4, or were otherwise classified as non-FDG-avid. Follow up FDG PET/CT were evaluated for recurrence. The presence of recurrence was determined by medical records with > 11 mo of follow-up. Results: Of the 372 subjects, 240 had FDG-avid primary tumors (64.5%; 59.7 y, male 175), whereas 132 had non-FDG-avid primary tumors (35.5%; 52.9 y, male 79). During follow-up, 72 patients (19.6%) were diagnosed to have recurrence. Among 63 cases with eligible follow-up PET/CT, 42 (3 at anastomosis site only) had FDG-avid primary tumors and 21 (2 at anastomosis site only) had non-FDG-avid tumors. For all recurrences, PET/CT sensitivity was 34/42 (81.0%) for the FDG-avid group and 11/21 (52.4%) for the non-FDG-avid group (P = 0.018). For recurrences outside the anastomosis site, PET/CT sensitivity was 41/58 (70.7%) for all subjects, 32/39 (82.1%) for the FDG-avid group, and 9/19 (47.4%) for the non-FDG-avid group (P = 0.006). PET/CT specificity for recurrence was 97.3%, 97.1%, and 97.5% for respective groups (P = n.s.). Conclusion: The result of our study showed that the detection sensitivity of recurrent gastric cancer by FDG PET/CT was superior in patients with FDG avid primary tumors than patients with FDG non-avid tumors. Hence, follow-up FDG PET/CT appears to have greater value for recurrence surveillance in patients with high tumor FDG uptake on initial PET/CT.

FDG-Avid Portal Vein Tumor Thrombosis from Hepatocellular Carcinoma in Contrast-Enhanced FDG PET/CT.

In this study, we aimed to describe the characteristics of portal vein tumor thrombosis (PVTT), complicating hepatocellular carcinoma (HCC) in contrast-enhanced FDG PET/CT scan. In this retrospective study, 9 HCC patients with FDG-avid PVTT were diagnosed by contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), which is a combination of dynamic liver CT scan, multiphase imaging, and whole-body PET scan. PET and CT DICOM images of patients were imported into the PET/CT imaging system for the re-analysis of contrast enhancement and FDG uptake in thrombus, the diameter of the involved portal vein, and characteristics of liver tumors and metastasis. Two patients with previously untreated HCC and 7 cases with previously treated HCC had FDG-avid PVTT in contrast-enhanced FDG PET/CT scan. During the arterial phase of CT scan, portal vein thrombus showed contrast enhancement in 8 out of 9 patients (88.9%). PET scan showed an increased linear FDG uptake along the thrombosed portal vein in all patients. The mean greatest diameter of thrombosed portal veins was 1.8 ± 0.2 cm, which was significantly greater than that observed in normal portal veins (P<0.001). FDG uptake level in portal vein thrombus was significantly higher than that of blood pool in the reference normal portal vein (P=0.001). PVTT was caused by the direct extension of liver tumors. All patients had visible FDG-avid liver tumors in contrast-enhanced images. Five out of 9 patients (55.6%) had no extrahepatic metastasis, 3 cases (33.3%) had metastasis of regional lymph nodes, and 1 case (11.1%) presented with distant metastasis. The median estimated survival time of patients was 5 months. The intraluminal filling defect consistent with thrombous within the portal vein, expansion of the involved portal vein, contrast enhancement, and linear increased FDG uptake of the thrombus extended from liver tumor are findings of FDG-avid PVTT from HCC in contrast-enhanced FDG PET/CT.

Bruxism—Before and After Images—on 18F-FDG PET/CT

Physical activity before F-FDG PET/CT can cause increased muscle glucose metabolism. We report markedly increased glucose metabolism in the masseter and temporalis muscles of a 53-year-old man who was clenching his teeth before the scan, and then resolution of this increased metabolism on a second scan 12 weeks later. SUVmax in the right masseter muscle was 26.9; 12 weeks later, the SUVmax was 1.6. This level of FDG uptake in bruxism has not yet been reported.

Predictive value of FDG PET/CT in pediatric Neuroblastoma patients

Purpose: To explore the prognosticvalue of F-18 FDG PET/CT inneuroblastoma patients. Materialsand method: comparative studywith 63 pathologically proved NBpatients with dominating high riskcategory (~65.1 %) who underwent F-18 FDG PET/CT using standardtechnique for purpose of initial, posttherapy or follow up assessment.Clinico-pathological, radiological andfollow up data were alsocollected.Results:FDG uptake levelwas expressed in terms of maximumstandardized uptake of the primarylesion against the maximumstandardized uptake of the referenceliver activity and maximumstandardized uptake of the primarylesion stands alone where ROC curvesmarked cut off values of 1.95 & 2.05respectively (both are almost doublethe reference hepatic activity). Themarked cut-off values were tested inrespect to the established clinicopathological features and the diseaseoutcome. we found significantrelationship between the Shimadaclassification and FDG uptake level,using 2.05 (cut-off value of the maxSUV of the primary lesion), where88.9% of those with favorablehistology exhibit low FDG tumoruptake , while on the contrary 51.9 %

The Ratio of 18F-FDG Activity Uptake Between the Right and Left Ventricle in Patients With Pulmonary Hypertension Correlates With the Right Ventricular Function

It is known that patients with pulmonary hypertension (PH) can have elevated F-FDG uptake in the right ventricle (RV) on PET imaging. This study was designed to assess possible relationship between FDG uptake of ventricles and the function/hemodynamics of the RV in patients with PH. Thirty-eight patients with PH underwent FDG PET imaging in both fasting and glucose-loading conditions. The standard uptake value (SUVs) corrected for partial volume effect in both RV and left ventricle (LV) were measured. The ratio of FDG uptake between RV to LV (SUVR/L) was calculated. Right heart catheterization and cardiac magnetic resonance (CMR) were performed in all patients within 1 week. The FDG uptake levels by the ventricles were compared with the result form the right heart catheterization and CMR. The SUV of RV (SUVR) and SUV of LV were significantly higher in glucose-loading condition than in fasting condition. In both fasting and glucose-loading conditions, SUVR and SUVR/L showed reverse correlation with right ventricular ejection fraction derived from CMR. In addition, in both fasting and glucose-loading conditions, SUVR and SUVR/L showed positive correlations with pulmonary vascular resistance. However, only SUVR/L in glucose-loading condition could independently predict right ventricular ejection fraction after adjusted for age, body mass index, sex, mean right atrial pressure, mean pulmonary arterial pressure, and pulmonary vascular resistance (P = 0.048). The FDG uptake of RV increases with decreased right ventricular function in patients with PH. Increased FDG uptake ratio between RV and LV might be useful to assess the right ventricular function.

Optical imaging of tumor vascularity associated with proliferation and glucose metabolism in early breast cancer: clinical application of total hemoglobin measurements in the breast.

BackgroundNear-infrared optical imaging targeting the intrinsic contrast of tissue hemoglobin has emerged as a promising approach for visualization of vascularity in cancer research. We evaluated the usefulness of diffuse optical spectroscopy using time-resolved spectroscopic (TRS) measurements for functional imaging of primary breast cancer.MethodsFifty-five consecutive TNM stageI/II patients with histologically proven invasive ductal carcinoma and operable breast tumors (<5 cm) who underwent TRS measurements were enrolled. Thirty (54.5%) patients underwent 18F-fluoro-deoxy-glucose (FDG) positron emission tomography with measurement of maximum tumor uptake. TRS was used to obtain oxyhemoglobin, deoxyhemoglobin, and total hemoglobin (tHb) levels from the lesions, surrounding normal tissue, and contralateral normal tissue. Lesions with tHb levels 20% higher than those present in normal tissue were defined as “hotspots,” while others were considered “uniform.” The findings in either tumor type were compared with clinicopathological factors.Results“Hotspot” tumors were significantly larger (P = 0.002) and exhibited significantly more advanced TNM stage (P = 0.01), higher mitotic counts (P = 0.01) and higher levels of FDG uptake (P = 0.0004) compared with “uniform” tumors; however, other pathological variables were not significantly different between the two groups.ConclusionsOptical imaging for determination of tHb levels allowed for measurement of tumor vascularity as a function of proliferation and glucose metabolism, which may be useful for prediction of patient prognosis and potential response to treatment.

OP0306 Evaluation of Disease Activity Using FDG PET-CT in Patients with Large Vessel Vasculitis

Background18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computerized tomography (CT) [PET/CT] has been proposed as a useful tool to diagnose and monitor activity of large vessel vasculitis (LVV), but its precise role...

Abstract P4-02-03: FDG PET/CT for early monitoring of response to neoadjuvant chemotherapy in breast cancer patients.

Abstract Introduction: Neoadjuvant chemotherapy (NAC), initially used only for locally advanced breast cancer, is now commonly used in patients with operable but large breast cancer or unfavorable tumor/breast size index because increases the chances of performing breast conservative surgery (BCS) instead of mastectomy in this group of patients. Patients and Methods: This is a prospective unicenter trial. FDG PET/CT were performed in 40 patients at baseline and after the second cycle of NAC. The level and relative changes in standardized uptake value (SUV) of FDG uptake were assessed regarding their ability to predict histopathologic response. Pathologic complete response (pCR) was defined as no malignant cells (no invasive ductal carcinoma and no ductal carcinoma in situ) identifiable in sections from the site of the tumor in the breast and in the axillary lymph node. Results: This prospectively study analyzed forty patients undergoing NAC, all female, age ranged 27–64 years (mean 41.0 years and median 38 years), all tumors were invasive ductal carcinoma, histological tumor grade 1, 2 and 3 were present respectively at 5%, 38.5% and 100% of the sample and nuclear grade 2 and 3 were present respectively at 12.5% and 87.5%. Estrogen receptor was positive in 60% of patients and the progesterone receptor was positive in 47.5% of patients. Her 2 was overexpressed in 12 patients (30%). Phenotype in this sample had the following distribution: 12.5% luminal A (5 patients), 50% Luminal B (20 patients: 14 patients with Ki-67&amp;gt; 14% and 6 cases with HER 2 overexpression), 15 % HER 2 (6 patients) and cases triple negative 9 (22.5%). size of the primary tumor ranged from 4.10 cm to 12.0 cm (mean 7.10 cm). The size of the primary tumor ranged from had a mean of 6.7 cm and a median of 6.0 cm. This group showed great uniformity in relation to primary chemotherapy. NAC with cyclophosphamide and adriamycin were administered to 38 patients. In this study, pCR was obtained in 12 patients (30%). Baseline FDG SUV referring to pCR group was 11.26 and 7.26 in non-pCR group (p = 0.04). FDG SUV after second cycle was 2.73 in pCR group and 4.64 in non-pCR group (p = 0.048). When analyzing ΔSUV (difference between baseline SUV and SUV after second cycle), pCR group had a mean reduction of 81.58% and non-pCR group had a mean reduction of 81.58% (p = 0.001). Receiver operating curve analyses were performed to deter mine optimal differentiation cut-off values of ΔSUV for differentiation of pCR and non-pCR. After two courses of NAC the optimal cutoff value to early differentiation between pCR from non-pCR were 59,1% in decrease of SUV. The sensitivity and specificity were 64,3% and 100,0%, respectively. Conclusion: The optimum role of FDG PET in predicting the response of breast cancers to neoadjuvant chemotherapy is still not clearly defined and the SUV cut-off needs to be validated. FDG-PET allows for prediction of treatment response by the level of FDG uptake in terms of SUV at baseline and after two cycles of chemotherapy and FDG-PET may be helpful for individual treatment stratification in breast cancer patients. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-02-03.

(18)F-FDG PET/CT Presentation in a Patient Diagnosed with Large Cell Neuroendocrine Carcinoma of Uncertain Primary.

A 61-year-old man attended for a 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT); he underwent a CT scan with contrast medium 2 days before, which showed numerous peritoneal nodules. He also had high levels of alpha-fetoprotein (500 mg/ml, normal < 20 mg/ml). 18F-FDG PET/CT showed an extended peritoneal involvement (Fig. 1a,b, and c); multiple pulmonary bilateral nodules and abdominal lymph nodes also had high levels of FDG uptake (Fig. 1d). Maximum standard uptake value (SUVmax) of the peritoneal lesions was 19.2. No clear primary could be found; in particular, no isolated uptakes in gastrointestinal tract could be detected, and pulmonary nodules were bilateral and small.

TH‐C‐213AB‐09: State‐Driven Mathematical Model Simulations of Tumor Response to Radiotherapy: How Does High FDG Uptake Relate to Classical Radiobiological Principles?

Purpose: High FDG‐PET tracer tumor uptake is well‐established to correlated to increased local failures and shorter overall survival. However, the relationship between uptake and classical radiobiological mechanisms is unclear. We explore the potential relationship between FDG‐PET uptake and classical radiobiolocial mechanisms using a mathematical framework. Methods: Tumor response was simulated using a novel, state‐driven tumor response model, including proliferating, hypoxic, and intermediate cell sub‐populations. Different potential relationships between FDG uptake and these cell populations were simulated. The uptake of FDG was assumed to be associated either with (1) the total number of viable cells, (2) the number of proliferative cells or (3) the number of intermediate cells. The predicted tumor doses for 50% control (TD50) in 2 Gy/fx were estimated for all possible initial conditions and correlated with the FDG uptake level for each assumption. Results: When the FDG uptake pattern was assumed to reflect the level of proliferation, the TD50 decreased with high FDG uptake. When the FDG was assumed to reflect the fraction of viable cells, only a weak positive correlation was observed between FDG uptake and TD50. As a surrogate of metabolically‐viable hypoxic cells, FDG uptake exhibited a strong positive correlation with TD50, consistent with clinical observations. Conclusions: Several different FDG uptake patterns were simulated using the model. Given the established clinical fact that FDG uptake correlates to a requirement of higher dose to achieve local control, the results support a potential avidity of FDG for cells in the intermediate stress state between being well‐oxygenated (and proliferating) and very poorly oxygenated (extremely hypoxic). Supported by the Enid A. Haupt Endowment for Medical Physics

Accuracy of CT-based attenuation correction in PET/CT bone imaging

We evaluate the accuracy of scaling CT images for attenuation correction of PET data measured for bone. While the standard tri-linear approach has been well tested for soft tissues, the impact of CT-based attenuation correction on the accuracy of tracer uptake in bone has not been reported in detail. We measured the accuracy of attenuation coefficients of bovine femur segments and patient data using a tri-linear method applied to CT images obtained at different kVp settings. Attenuation values at 511 keV obtained with a 68Ga/68Ge transmission scan were used as a reference standard. The impact of inaccurate attenuation images on PET standardized uptake values (SUVs) was then evaluated using simulated emission images and emission images from five patients with elevated levels of FDG uptake in bone at disease sites. The CT-based linear attenuation images of the bovine femur segments underestimated the true values by 2.9 ± 0.3% for cancellous bone regardless of kVp. For compact bone the underestimation ranged from 1.3% at 140 kVp to 14.1% at 80 kVp. In the patient scans at 140 kVp the underestimation was approximately 2% averaged over all bony regions. The sensitivity analysis indicated that errors in PET SUVs in bone are approximately proportional to errors in the estimated attenuation coefficients for the same regions. The variability in SUV bias also increased approximately linearly with the error in linear attenuation coefficients. These results suggest that bias in bone uptake SUVs of PET tracers ranges from 2.4% to 5.9% when using CT scans at 140 and 120 kVp for attenuation correction. Lower kVp scans have the potential for considerably more error in dense bone. This bias is present in any PET tracer with bone uptake but may be clinically insignificant for many imaging tasks. However, errors from CT-based attenuation correction methods should be carefully evaluated if quantitation of tracer uptake in bone is important.

Prognostic impact of hexokinase and glucose transporter expressions and clinicopathologic features related to F-18-FDG uptake in esophageal cancer.

39 Background: Elucidation of prognostic predictors based on biological viability may be useful for a better detection of patients with a high risk of relapse or death from esophageal cancer. Methods: Maximum standardized uptake values (SUVmax) were measured in the preoperative 18F-FDG positron emission tomography (PET) scans of 47 patients who had a radical esophageal resection without previous treatment. Expression levels of hexokinase-II (HK-II), glucose transporter I (GLUT-I), hypoxia inducible factor-1α (HIF-Iα), vascular endothelial growth factor (VEGF), p53 and the proliferative activity (MIB-I score) were determined immunohistochemically on paraffin-embedded tumor tissue. Correlations and survival functions were calculated to identify independent correlations between FDG-uptake and prognostic expression levels. Results: High HK-II expression was significantly correlated with reduced SUVmax values (p= 0.002) and HK-II expression was significant higher among adenocarcinomas than squamous cell carcinomas (36/37 vs. 5/9, p= 0.004). The five years survival was significant better for patients with SUVmax≤ 3 in their primary tumors (75% vs. 25%) and a lymph node (LN) ratio ≤0.20 (40% vs. 6%). There were also significant disease free survival benefits for different expression rates of GLUT-I, p53 and MIB (log rank p= 0.03, p= 0.03 and p= 0.04 respectively) in patients with a lymph node ratio &gt;0.20. Conclusions: FDG-uptake and LN ratio are strong prognostic predictors in patients with esophageal cancer. The level of GLUT-I and p53 expression and the MIB score may be useful prognostic markers that provide information about tumor aggressiviness in esophageal cancer.

Automatic tumour delineation in whole body PET/CT images

We propose a new method for automated delineation of tumour boundaries by using joint information from whole-body PET and diagnostic CT images. Due to varying levels of FDG uptake in different organs, we apply locally adaptive thresholds of SUV to acquire an initial estimate of hot spot locations and shape in PET images. The hot spot boundaries are further improved by applying Competition Diffusion (CD) and Mode-Seeking Region Growing (MSRG) algorithms. These hot spots seen in PET are then confirmed and more accurately segmented considering CT information, through the Joint Likelihood Ratio Test technique for probabilistic integration. Experiments show that the proposed multi-modal method achieves more accurate and reproducible tumour delineation than using PET or CT alone.

Abstract B38: Troglitazone enhances breast cancer cell 18F-FDG uptake and intracelluar lactic acid accumulation through PPAR-r independent activation of the MAPK pathway.

Abstract Purpose: There is growing interest in the anti-tumor effects of thiazolidinediones including troglitazone (TGZ). In this study, we assessed how TGZ acts on cancer cell glucose uptake, and further investigated its mechanism and relation to cancer cell survival. Methods: T47D human breast cancer cells were treated with TGZ and measured for trypan blue and MTT assay-based cell viability, FDG uptake, intra- and extracellular lactic acid levels, and superoxide production. Involvement of signaling pathways for FDG uptake was investigated with specific kinase inhibitors and Western blots. Results: TGZ caused dose-dependent suppression of T47D cell survival, and glucose deprivation substantially enhanced the killing effect from 15.6% to 84.2% of cells. However, in contrast to energy restriction mimetic agents that reduced FDG uptake, TGZ stimulated a prompt increase of FDG uptake that reached 245.0% of controls by 10 μM at 1 h. This response was poorly replicated by rosiglitazone and was unaffected by GW9662, indicating a PPAR-independent mechanism of action. TGZ rapidly stimulated mitogen-activated protein kinase (MAPK) activity, and inhibition of this pathway with PD98059, as well as inhibition of epidermal growth factor receptor (EGFR) activity with BIBX1382, completely abrogated the ability of TGZ to enhance FDG uptake. The increase in glucose uptake was accompanied by elevated lactic acid accumulation in the cells but not culture media. This indicates that TGZ stimulates glycolytic activity but suppresses lactic acid extrusion, which may contribute to its anti-tumor effects. Conclusion: TGZ-induced suppression of T47D cell survival is potentiated by restricted glucose availability, but is uniquely accompanied by enhanced FDG uptake that occurs via PPAR-independent MAPK activation. This is associated with an increase in glycolytic metabolism along with suppression of lactic acid extrusion, which may play a role in the anti-tumor effect of TGZ. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B38.

The early metabolic effect of zolendronic acid on FDG-PET scans in patients with bone metastasis.

e21168 Background: 18-fluorodeoxyglucose (FDG) positron emission tomography combined with computerized tomography (FDG-PET/CT) is widely used in staging of several cancers. Any agent that can cause a decreased uptake of FDG by tumor cells can lead to inaccurate staging of the cancer. Bisphosphonates are routinely administered to patients with bone metastasis to reduce the morbidity related to skeletal events. Recently, it was shown that zolendronic acid (ZA) has also antitumor effects due to several potential mechanisms, including the induction of tumor cell apoptosis, inhibition of tumor cell invasion/migration, activation of anticancer tumor responses and anti-angiogenic effects. Although we know that the interval between the last dose of chemotherapy and the PET/CT study is important for reliable interpretation, the effect of ZA on maximum standardized uptake values (SUVmax) on FDG-PET scans in cancer pts with bone metastasis is not identified. Methods: The primary aim for this trial was to assess the change in maximum SUVs of tumor lesions on PET/CT, 72 hour after the administration of ZA therapy in pts with bone metastasis. Twelve pts (6 male, 6 female) with newly diagnosed cancer having bone metastasis on FDG-PET/CT were prospectively enrolled to this trial. Pts were chemotherapy-naïve. No prior or concurrent use of bisphosphonates was allowed. Pts received 4 mg of intravenous ZA and PET/CT was done 72 hours later. Results: The median age of pts was 59 years (38-70). The primary tumors were non-small cell lung cancer (n=7), breast cancer (n=3), renal cell carcinoma (n=1) and gastric neuroendocrine tumor (n=1). When baseline PET/CT was compared with the PET/CT that was done 72 hours after ZA administration, no significant change was detected in the SUVmax of the bone lesions and SUVmax of the primary lesion. In 3 pts, some bone lesions became metabolically unrecognizable after ZA administration, but the stage did not change in these pts. These lesions had a relatively low SUVmax on baseline PET/CT. Conclusions: Our results suggest that administration of ZA prior to staging with PET/CT does not seem to affect the FDG-uptake level of tumor lesions in PET/CT.

Residual metabolic tumor activity after chemo-radiotherapy is mainly located in initially high FDG uptake areas in rectal cancer

Purpose Recent literature suggests that tumor cells and areas within tumors with a high initial FDG uptake might be more resistant to (chemo)radiotherapy ((C)RT). This study was undertaken to test this hypothesis in rectal cancer using rigid and non-rigid image registration. Patients and methods Twenty-eight patients, diagnosed with locally advanced rectal cancer and referred for pre-operative treatment with CRT were included in this study. All patients underwent FDG-PET–CT imaging prior to and after CRT. Rigid and non-rigid image registration was performed to compensate organ deformations between the pre- and post-treatment PET–CT scans. The tumor was contoured on both PET-scans using SUV iso-contouring based on the SBR-method. The voxels with residual increased FDG uptake were studied and correlated to their pre-treatment FDG uptake level. Two SUV–volume-histograms were made based on the pre-treatment PET-data, one for the voxels within the pre-treatment tumor PET-based iso-contour and one for the voxels within the PET-based iso-contour of the residual tumor non-rigidly registered onto the pre-treatment scan. Results For the voxels with a pre-treatment FDG uptake of >50% of SUV max, 70.6 ± 5.6% of the voxels were still metabolic active in the residual tumor, whereas for voxels with an FDG uptake of <50% of SUV max only 51.1 ± 6.7% were present in the metabolic active residual tumor. Conclusion This study presents areas in rectal tumors with an initially high FDG uptake to be most likely to show residual disease after CRT. This could indicate a higher (C)RT-resistance for tumor regions with a high FDG uptake prior to treatment.

Repeated Positron Emission Tomography-Computed Tomography and Perfusion-Computed Tomography Imaging in Rectal Cancer: Fluorodeoxyglucose Uptake Corresponds With Tumor Perfusion

The purpose of this study was to analyze both the intratumoral fluorodeoxyglucose (FDG) uptake and perfusion within rectal tumors before and after hypofractionated radiotherapy. Rectal cancer patients, referred for preoperative hypofractionated radiotherapy (RT), underwent FDG-positron emission tomography (PET)-computed tomography (CT) and perfusion-CT (pCT) imaging before the start of hypofractionated RT and at the day of the last RT fraction. The pCT-images were analyzed using the extended Kety model, quantifying tumor perfusion with the pharmacokinetic parameters K(trans), v(e), and v(p). The mean and maximum FDG uptake based on the standardized uptake value (SUV) and transfer constant (K(trans)) within the tumor were correlated. Also, the tumor was subdivided into eight subregions and for each subregion the mean and maximum SUVs and K(trans) values were assessed and correlated. Furthermore, the mean FDG uptake in voxels presenting with the lowest 25% of perfusion was compared with the FDG uptake in the voxels with the 25% highest perfusion. The mean and maximum K(trans) values were positively correlated with the corresponding SUVs (ρ = 0.596, p = 0.001 and ρ = 0.779, p < 0.001). Also, positive correlations were found for K(trans) values and SUVs within the subregions (mean, ρ = 0.413, p < 0.001; and max, ρ = 0.540, p < 0.001). The mean FDG uptake in the 25% highest-perfused tumor regions was significantly higher compared with the 25% lowest-perfused regions (10.6% ± 5.1%, p = 0.017). During hypofractionated radiotherapy, stable mean (p = 0.379) and maximum (p = 0.280) FDG uptake levels were found, whereas the mean (p = 0.040) and maximum (p = 0.003) K(trans) values were found to significantly increase. Highly perfused rectal tumors presented with higher FDG-uptake levels compared with relatively low perfused tumors. Also, intratumor regions with a high FDG uptake demonstrated with higher levels of perfusion than regions with a relatively low FDG-uptake. Early after hypofractionated RT, stable FDG uptake levels were found, whereas tumor perfusion was found to significantly increase.

PET/BT’de Radyasyona Bağlı Akciğer Hasarı: Küçük Hücreli Dışı Akciğer Kanseri Hastalarında Belirli Eş Doz Radyasyon Bölgelerinde FDG Tutulum Yanıtının Analizi

Objective: Inflammatory response associated with radiation-induced lung injury (RILI) results in an increased 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT). In this study, we aimed to analyze the degree of FDG uptake within specific isodose regions (IR) of the irradiated lung using standardized uptake value (SUV) measurements, and to correlate posttreatment FDG uptake with radiotherapy (RT) dose parameters, patient characteristics and the imaging time interval after RT completion. Material and Methods: Data from 30 patients with non-small cell lung cancer (NSCLC) who underwent FDG PET/CT imaging at least 12 weeks (72-668 days) after completion of RT were evaluated. In each patient, side-by-side visual registration of the treatment planning CT slices including IR curves with the corresponding PET/CT slices was performed. Using SUV measurements, FDG uptake levels were analyzed within specific IRs of the irradiated lung. The statistical difference between SUVmax of each IR was determined. The RT dose parameters, patient characteristics and time interval between RT and PET/CT were tested for correlation with SUVmax of IRs. Results: The mean SUVmax in the IRs of the lung that received 2000-4000cGy was 1.51 ± 0.66 (mean ± SD) (min-max: 0.69-2.84), 4000-6000cGy was 2.67 ± 1.16 (min-max: 0.71-6.0), and >6000Gy was 3.55 ± 1.09 (min-max: 1.2-5.72). We found statistically significant differences between the SUVmax values of all IRs (SUV2000 vs. SUV4000, p= 0.001; SUV2000 vs.6000, p= 0.002; SUV4000 vs. 6000, p= 0.001). No statistically significant correlation was found between SUVmax and the other variables. Conclusion: The findings of this study showed that, although some overlap occurs between IRs, the degree of radiation-related parenchymal FDG uptake gets higher with increasing dose levels. Persistent high FDG uptake levels may be observed in radiation fibrosis areas on PET/CT even several months after RT.