Incidental head and neck <Superscript>18</Superscript>F-FDG uptake on PET/CT without corresponding morphological lesion: early predictor of cancer development?

Purpose  To retrospectively determine whether increased/asymmetric FDG uptake on PET without a correlating morphological lesion on fully diagnostic CT indicates the development of a head and neck malignancy. Methods  In 590 patients (mean age 55.4 ± 13.3 years) without a head and neck malignancy/inflammation FDG uptake was measured at (a) Waldeyer’s ring, (b) the oral floor, (c) the larynx, and (d) the thyroid gland, and rated as absent (group A), present (group B), symmetric (group B1) or asymmetric (group B2). Differences between groups A and B and between B1 and B2 were tested for significance with the U-test (p < 0.05). An average follow-up of about 2.5 years (mean 29.5 ± 13.9 months) served as the reference period to determine whether patients developed a head and neck malignancy. Results  Of the 590 patients, 235 (40%) showed no evidence of enhanced FDG uptake in any investigated site, and 355 (60%) showed qualitatively elevated FDG uptake in at least one site. FDG uptake values (SUV_max, mean±SD) for Waldeyer’s ring were 3.0 ± 0.89 in group A (n = 326), 4.5 ± 2.18 in group B (n = 264; p < 0.01), 5.4 ± 3.35 in group B1 (n = 177), and 4.1 ± 1.7 in group B2 (n = 87; p < 0.01). Values for the oral floor were 2.8 ± 0.74 in group A (n = 362), 4.7 ± 2.55 in group B (n = 228; p < 0.01), 4.4 ± 3.39 in group B1 (n = 130), and 5.1 ± 2.69 in group B2 (n = 98, p = 0.01). Values for the larynx were 2.8 ± 0.76 in group A (n = 353), 4.2 ± 2.05 in group B (n = 237; p < 0.01), 4.0 ± 2.02 in group B1 (n = 165), and 4.6 ± 2.8 in group B2 (n = 72; p = 0.027). Values for the thyroid were 2.4 ± 0.63 in group A (n = 404), 3.0 ± 1.01 in group B (n = 186; p < 0.01), 2.6 ± 0.39 in group B1 (n = 130), and 4.0 ± 1.24 in group B2 (n = 56; p < 0.01). One patient developed a palatine tonsil carcinoma (group B1, SUV_max 3.2), and one patient developed an oral floor carcinoma (group B1, SUV_max 3.7). Conclusion  Elevated/asymmetric head and neck FDG accumulation without a correlating morphological lesion can frequently be found and does not predict cancer development. In populations in which goitre is endemic, FDG uptake by the thyroid is common and not associated with thyroid cancer.     

Impact of FDG PET on the preoperative staging of newly diagnosed breast cancer

Purpose The main objective of this study was to determine the efficacy of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) to assess the impact of this technique in staging of patients with newly diagnosed breast cancer. Methods Two hundred and seventy-one consecutive patients (median age = 51 ± 11 years) with biopsy-proven primary breast cancer who were examined by FDG PET were enrolled in this prospective preoperative staging study. Whole-body FDG-PET images were acquired approximately 60 min after the intravenous administration of FDG (5.2 MBq/kg). Visual assessment and the maximum standardized uptake value (SUVmax) of breast lesions for semiquantitative analysis were carried out. The PET results were compared with the histopathology results. Results For the tumor, node, metastases (TNM) staging, 240 patients (250 breasts) were considered eligible based on the criteria that were established for this analysis. Significant differences were noted in SUVmax of lesions according to the TNM staging (p < 0.05). The average SUVmax of the primary tumor was calculated in patients with axillary involvement (n = 58) and for the ones without axillary metastasis (n = 79), and SUVmax were 4.1 ± 3.5 and 2.8 ± 2.3, respectively, with a significant difference between the two groups (p = 0.03). PET imaging revealed pathological FDG uptake in 54% (46/85) of patients with axillary lymph node metastases. The sensitivities of FDG PET for detecting axillary lymph node metastasis were found 41% in pN1, 67% in pN2, and 100% in pN3, and the specificity was 89% for pN0 stage. Detection of extra-axillary regional node or distant metastatic lesions revealed by PET scan in 22 of 24 patients resulted in a significant change in the TNM stage. Distant metastasis without axillary lymph node metastasis was noted in 21% (5/24) of patients. The results revealed that FDG PET upgraded TNM stage in 9.2% (22/240) of patients and 7.5% (18/240) of patients were diagnosed as having one or more distant metastases. Conclusion FDG PET was able to identify extra-axillary regional nodal and distant lesions in newly diagnosed patients with breast cancer; FDG PET may alter the staging and management of therapy in patients with newly diagnosed breast cancer.     

Prediction of tumor response by FDG-PET: comparison of the accuracy of single and sequential studies in patients with adenocarcinomas of the esophagogastric junction

Purpose Positron-emission-tomography with the glucose analog fluorodeoxyglucose (FDG-PET) has shown encouraging results for prediction of tumor response to chemotherapy. However, there is no consensus as to what time after initiation of therapy FDG-PET should be performed. To address this question we studied the time course of changes in tumor FDG-uptake in patients with locally advanced adenocarcinomas of the esophagogastric junction (AEG) treated with preoperative chemotherapy. Methods Twenty-four patients with AEG were included and underwent FDG-PET prior to therapy (PET1), 2 weeks after initiation of therapy (PET2), and preoperatively (PET3). Tumor metabolic activity was assessed by standardized uptake values (SUV) and correlated with histopathologic response and patient survival. Results Baseline tumor SUV was 8.3 ± 3.5 and decreased to 5.0 ± 1.8 at PET2 (p  <  0.0001). At PET3 there was further decrease to 3.5 ± 1.9 (p < 0.0001). The relative decrease of tumor FDG-uptake from PET1 to PET2 and from PET1 to PET3 were both significantly correlated with histopathologic response. Reduction of tumor SUV from PET1 to PET2 was significantly correlated with survival (p = 0.03) and there was a similar trend for changes from PET1 to PET3 (p = 0.09). In contrast, absolute SUVs did not demonstrate a significant correlation with histopathological response or patient survival at any of the studied time points. Conclusion In patients with AEG, relative changes in tumor FDG uptake are better predictors for treatment outcome than absolute SUVs. Metabolic changes within the first 2 weeks of therapy are at least as efficient for prediction of histopathologic response and patient survival as later changes.     

[<Superscript>18</Superscript>F]FDG-PET predicts complete pathological response of breast cancer to neoadjuvant chemotherapy

Purpose To evaluate, in breast cancer patients treated by neoadjuvant chemotherapy, the predictive value of reduction in FDG uptake with regard to complete pathological response (pCR). Methods Forty-seven women with non-metastatic, non-inflammatory, large or locally advanced breast cancer were included. Tumour uptake of FDG was evaluated before and after the first course of neoadjuvant chemotherapy. Four indices were used: maximal and average SUV without or with correction by body surface area and glycaemia (SUV_max, SUV_avg, SUV_max-BSA-G and SUV_avg-BSA-G, respectively). The predictive value of reduction in FDG uptake with respect to pCR was studied by logistic regression analysis. Relationships between baseline [¹⁸F]FDG uptake and prognostic parameters were assessed. Results The relative decrease in FDG uptake (ΔSUV) after the first course of neoadjuvant chemotherapy was significantly greater in the pCR group than in the non-pCR group (p < 0.000066). The four FDG uptake indices were all strongly correlated with each other. A decrease in SUV_max-BSA-G of 85.4% ± 21.9% was found in pCR patients, versus 22.6% ± 36.6% in non-pCR patients. ΔSUV_max-BSA-G <−60% predicted the pCR with an accuracy of 87% and ΔSUVs were found to be only factors predictive of the pCR at multivariate analysis. An elevated baseline SUV was associated with high mitotic activity (p < 0.0016), tumour grading (p < 0.004), high nuclear pleomorphism score (p < 0.03) and negative hormonal receptor status (p < 0.005). Conclusion In breast cancer patients, after only one course of neoadjuvant chemotherapy the reduction in FDG uptake is an early and powerful predictor of pCR.     

Differentiation between malignant and benign pathologic fractures with F-18-fluoro-2-deoxy-<Emphasis Type="SmallCaps">D</Emphasis>-glucose positron emission tomography/computed tomography

Objective To evaluate the efficacy of F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in differentiating malignant from benign pathologic fractures. Materials and methods F-18 FDG PET/CT was performed on 34 patients with pathologic fractures between May 2004 and June 2007. Fractures were located in tubular bones (26), in the pelvis (six), in the spine (one) and in a rib (one). The FDG uptake pattern at the fracture site was described, whether FDG uptake occurred in the marrow or cortex and soft tissue. Maximum standardized uptake values (SUVmax, the largest value at the region of interest) were measured at the fracture site, including cortical bone, bone marrow and soft tissue. As a reference standard, biopsy was used for 12 patients and clinical follow-up for 22 patients. Sensitivity, specificity and diagnostic accuracy of PET/CT were calculated. Results There were 19 malignant and 15 benign fractures. In the malignant fractures, PET/CT demonstrated high (mean SUVmax 12.0, range 4.3 to 45.7) F-18 FDG uptake in bone marrow in most cases (17 of 19). In benign fractures, there was low FDG uptake (mean SUVmax 2.9, range 0.6 to 5.5) within cortical bone or adjacent soft tissue around the fracture, rarely in the marrow. There were significant differences in the pattern of intramedullary FDG uptake (P < 0.001) and in the mean SUVmax (P < 0.01) between malignant and benign fractures. The sensitivity, specificity and diagnostic accuracy of F-18 FDG PET/CT were 89.5%, 86.7% and 88.2%, respectively, with a cut-off SUVmax set at 4.7. The time interval between fracture and PET/CT did not significantly influence FDG uptake at the fracture site. Conclusion F-18 FDG PET/CT reliably differentiated between malignant and benign fractures based on the SUVmax and based on medullary uptake, which was characteristic for malignant fractures. This research was supported by the Yeungnam University research grants in 2007.     

Detection of gastric cancer using <Superscript>18</Superscript>F-FLT PET: comparison with <Superscript>18</Superscript>F-FDG PET

Purpose  We prospectively investigated the feasibility of 3′-deoxy-3′-¹⁸F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of gastric cancer, in comparison with 2-deoxy-2-¹⁸F-fluoro-d-glucose (FDG) PET, and determined the degree of correlation between the two radiotracers and proliferative activity as indicated by Ki-67 index. Methods  A total of 21 patients with newly diagnosed advanced gastric cancer were examined with FLT PET and FDG PET. Tumour lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. Results  For detection of advanced gastric cancer, the sensitivities of FLT PET and FDG PET were 95.2% and 95.0%, respectively. The mean (±SD) SUV for FLT (7.0 ± 3.3) was significantly lower than that for FDG (9.4 ± 6.3 p < 0.05). The mean FLT SUV and FDG SUV in nonintestinal tumours were higher than in intestinal tumours, although the difference was not statistically significant. The mean (±SD) FLT SUV in poorly differentiated tumours (8.5 ± 3.5) was significantly higher than that in well and moderately differentiated tumours (5.3 ± 2.1; p < 0.04). The mean FDG SUV in poorly differentiated tumours was higher than in well and moderately differentiated tumours, although the difference was not statistically significant. There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV. Conclusion  FLT PET showed as high a sensitivity as FDG PET for the detection of gastric cancer, although uptake of FLT in gastric cancer was significantly lower than that of FDG.     

Aortic inflammation,as assessed by hybrid FDG-PET/CT imaging,is associated with enhanced aortic stiffness in addition to concurrent calcification

Purpose  To analyse the relationship between: (i) aortic pulse wave velocity (PWV), an index of aortic stiffness with strong prognostic significance, and (ii) aortic calcification and inflammation, which were quantified by hybrid imaging with X-ray computed tomography (CT) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Methods  Central aortic (carotid-femoral) and peripheral (carotid-brachial and femoral-tibial) PWV were recorded in 26 patients, who had been routinely referred for dual FDG-PET/CT imaging. Results  In univariate analyses, central aortic PWV was strongly linked to the volume of calcifications (VCa) and an enhanced FDG activity, when determined by averaging standardized uptake values (SUV_max). By multivariate stepwise analysis including age and gender, both VCa (p < 0.0001) and SUV_max (p < 0.01) were significant determinants of PWV explaining 61% and 11% of its variability. Conclusion  Aortic inflammation, assessed by hybrid FDG-PET/CT imaging, is associated with an enhanced aortic stiffness, in addition to the concurrent impact of calcifications.     

<Superscript>18</Superscript>F-FDG PET analysis of schwannoma: increase of SUVmax in the delayed scan is correlated with elevated VEGF/VPF expression in the tumors

Objective  In order to clarify the increased 2-deoxy-2-fluoro-¹⁸F-d-glucopyranose (¹⁸F-FDG) accumulation in schwannoma by positron emission tomography (PET) analysis, immunohistochemical analysis for the factors involved in glucose transportation and vascular formation was performed. Materials and methods  Twenty-six patients with schwannoma (13 men and 13 women) with ages ranging from 27 to 75 years, who received whole body ¹⁸F-FDG PET scan, were enrolled for the present study. The retention index (RI) was calculated by dividing the increase in the standardized uptake value (SUVmax) at the delayed scan by the SUVmax in the early scan. SUVmax and RI were compared with the histologic variables, including the expression of glucose transporters 1 and 3, hexokinase II, vascular endothelial growth factor/vascular permeability factor (VEGF/VPF), and microvascular density shown by CD31 immunohistochemistry. Results  Mean SUVmax values in the early and delayed scans were 2.64 ± 1.47 and 2.71 ± 1.57 (mean ± SD), respectively. RI was −2.5 ± 21 (percentage). SUVmax showed a positive correlation with the tumor size (tumor size <5 cm, 2.06 ± 0.72; >5 cm, 3.95 ± 1.89; p < 0.05) and the microvascular density (negative density, 2.16 ± 1.12; positive density, 3.56 ± 1.67; p < 0.05). RI correlated with VEGF/VPF expression in the tumors (negative expression, −11 ± 6.1; positive expression, 13 ± 8.1; p < 0.05). Other factors showed no correlation with SUVmax or RI. Conclusions  Microvascular density and vascular permeability of the tumor are suggested to affect the enhanced ¹⁸F-FDG accumulation in schwannoma.     

The efficacy of whole-body FDG-PET or PET/CT for autoimmune pancreatitis and associated extrapancreatic autoimmune lesions

Purpose The aim of this study was to evaluate retrospectively the efficacy of whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) for autoimmune pancreatitis (AIP) and associated extrapancreatic autoimmune lesions. Methods Whole-body FDG-PET or PET/computed tomography (CT) findings were reviewed in six patients with AIP. The initial PET scans were performed 1 h and 2 h after FDG injection in all six patients. Follow-up PET scans were performed during or following steroid therapy in five patients and in one patient who did not have steroid therapy. Results The initial PET scans revealed intense FDG uptake by AIP in all six patients. The maximum standardized uptake value (SUVmax) increased in four patients and was stable in two patients. The intense uptake in the pancreas disappeared during or following steroid therapy in five patients and in one patient who showed spontaneous remission of AIP. Abnormal FDG uptake by extrapancreatic autoimmune diseases was observed in five of the six patients: sclerosing sialadenitis (n = 5), lymphadenopathy (n = 5), retroperitoneal fibrosis (n = 2), interstitial nephritis (n = 2) and sclerosing cholecystitis (n = 1). Abnormal FDG uptake disappeared in the salivary glands (n = 4), lymph nodes (n = 4), retroperitoneum (n = 2), kidneys (n = 1) and gallbladder (n = 1) during or following steroid therapy and remained in the salivary glands and lymph nodes of a spontaneous remission patient. Conclusion These results suggest that whole-body FDG-PET may be useful for detecting AIP and associated extrapancreatic autoimmune lesions and for monitoring their disease activity but that dual time point imaging may not be useful for differentiating malignancy from AIP.     

Dual-time point 18F-FDG PET/CT scan for differentiation between 18F-FDG-avid non-small cell lung cancer and benign lesions

Objective  The aim of this study is to clarify the difference of F-18 FDG uptake kinetics between FDG-avid non-small-cell lung cancer (NSCLC) and benign lesions associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. Materials and methods  The materials were 76 FDG-avid solitary NSCLC in 76 patients and 57 FDG-avid solitary benign lesions associated with various etiologies in 61 patients. FDG PET/CT scan was performed at 60 and 120 min after intravenous injection of 4.4 MBq/kg F-18 FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%ΔSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis and evaluation of diagnostic accuracy. Results  The mean ± SD of early SUV max, delayed SUVmax and %ΔSUVmax were 8.3 ± 5.2, and 10.2 ± 6.5, and 21.9% ± 18.9 in FDG-avid NSCLC, and 3.8 ± 3.2, 4.0 ± 3.7, and 11.3% ± 26.0 in FDG-avid benign lesions, respectively. Delayed SUVmax in NSCLC was significantly higher than early SUVmax (P < 0.0001); while not different in benign lesions. Percent change of SUVmax in NSCLC was also significantly higher than that in benign lesions (P < 0.01). The optimal parameter for the differentiation was delayed SUVmax > 5.5 and yielded sensitivity of 77.6%, specificity of 80.7% and accuracy of 78.9%, which provided better differentiation than the use of %ΔSUVmax or the traditional parameter of early SUVmax > 2.5. However, 11 (19.2%) benign lesions were indistinguishable from NSCLC. Conclusion  Although delayed PET/CT scan enhances the difference of FDG uptake between FDG-avid NSCLC and benign lesions, and the use of delayed SUVmax > 5.5 appears to improve the differentiation of these hypermetabolic lesions compared with an early scan, careful interpretation and management for correct differentiation are still required.     

Comparison of MET-PET and FDG-PET for differentiation between benign lesions and lung cancer in pneumoconiosis

Objective The aim of this study was to evaluate and compare the ability of C-11-methionine (MET) and F-18 fluoro-deoxy-d-glucose positron emission tomography (FDG-PET) to diagnose lung cancer in patients with pneumoconiosis. Methods Twenty-six subjects underwent both whole-body MET-PET and FDG-PET on the same day. The first group was a lung cancer group, which consisted of 15 patients, and included those with pneumoconiosis with increased nodules (13 cases), hemoptysis (1 case), and positive sputum cytology (1 case). The second group was a no-malignancy control group, consisting of 11 patients with pneumoconiosis. Results Significant correlations between nodule size and the maximum standardized uptake value (SUV_max) of the two PET tracers were observed in the control group. The larger the nodule size, the greater were the amounts of these tracers accumulated (MET: r = 0.771, P < 0.0001; FDG: r = 0.903, P < 0.0001). The SUV_max of MET was significantly lower than that of FDG in the pneumoconiotic nodules (P < 0.0001). Lung cancer was found in 5 of 19 nodules (two with adenocarcinoma, one with squamous cell carcinoma, one with small cell carcinoma, and one with large cell carcinoma) in the first group. As for nodules equal to or less than 3 cm in diameter, the SUV_max of MET was significantly higher in the lung cancer than in the pneumoconiotic nodules, with 3.48 ± 1.18 (mean ± SE) for the lung cancer and 1.48 ± 0.08 for the pneumoconiotic nodules (P < 0.01), similar to the SUV_max of FDG, with 7.12 ± 2.36 and 2.85 ± 0.24 (P < 0.05), respectively. On the basis of the criteria for the control group, FDG and MET identified lung cancer with sensitivities of 60% and 80%, specificities of 100% and 93%, accuracies of 90% and 90%, positive predictive values of 100% and 80%, and negative predictive values of 88% and 93%, respectively. Conclusions Our results indicate that nodules with an intense uptake of MET and FDG relative to their size should be carefully observed because of a high risk for lung cancer.     

Differentiation of FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer with dual-time point F-18-fluorodeoxy-glucose PET/CT scan

Objective  To evaluate the ability of dual-time point F-18-fluorodeoxy-glucose (FDG) PET/CT scans to differentiate FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer. Methods  A total of 64 FDG-avid recurrent lesions (local tumor recurrence or lymph node metastases) in 52 patients and 38 FDG-avid compromised benign lesions after surgery in 37 patients were included in the study. FDG PET/CT study was performed at 60 and 120 min after intravenous injection of 3.5 MBq/kg FDG. The maximum SUV (SUVmax) on the early and delayed scans and the percent change of SUVmax (%ΔSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis. Results  The average early SUVmax, delayed SUVmax and ΔSUVmax% were 4.9 ± 2.6, 6.0 ± 3.6 and 18.2% ± 18.8 in FDG-avid recurrent lesions, and 2.1 ± 0.8, 1.8 ± 1.0 and −17.8% ± 21.3 in FDG-avid benign lesions, respectively. Delayed SUVmax was significantly increased compared with early SUVmax in recurrent lesions (P < 0.0001), while it was decreased in benign lesions (P < 0.0001). All the three parameters in recurrent lesions were significantly higher than those in benign lesions (P < 0.0001). The highest diagnostic accuracy of the differentiation was achieved by the combined use of the optimal parameter of delayed SUVmax > 2.5 and %ΔSUVmax > 0%, with a sensitivity of 90.6%, specificity of 81.5%, accuracy of 87.2%, NPV of 89.2%, and PPV of 83.7%, which were better than the respective values obtained with the use of delayed SUVmax > 2.5 alone or %ΔSUVmax > 0% alone (P < 0.005 and P < 0.05, respectively), and the use of the traditional parameter of early SUVmax > 2.5 (P < 0.005). Conclusions  This approach with SUVmax estimation appears to improve the differentiation between FDG-avid loco-regional recurrent of breast cancer and compromised benign lesions after surgery, since delayed scanning significantly enhances the difference in FDG uptake between these lesions.     

Prognostic utility of FDG PET/CT in advanced ovarian,fallopian and primary peritoneal high-grade serous cancer patients before and after neoadjuvant chemotherapy

In patients with advanced ovarian, fallopian and primary peritoneal carcinoma, complete interval debulking surgery (IDS) is often performed after neoadjuvant chemotherapy (NAC) to achieve long progression-free survival (PFS) and overall survival (OS). We aimed to investigate the utility of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG) PET/CT in patients with these malignancies who underwent complete IDS. Between 2009 and 2017, twenty-two patients underwent FDG PET/CT scans before and after NAC. The highest SUVmax/peak (standardized uptake value), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) for whole lesions were defined as target SUVmax/peak, tMTV and tTLG, respectively. We also calculated these reduction rates during NAC. These parameters were compared between the groups with platinum-free interval (PFI) > 12 months (n = 10) and those with PFI ≤ 12 months (n = 12). The PFS and OS were evaluated using these quantitative parameters, and in terms of the presence of visually detectable residual lesions after NAC. The target SUVmax/peak before NAC, the reduction rates in the target SUVmax, tMTV and tTLG were significantly higher in the group with PFI > 12 months than the shorter PFI group (p < 0.05). Especially in PFS, the higher reduction rates in the target SUVmax/peak, tMTV, and tTLG had an excellent prognostic stratification (p < 0.05) and the FDG visually negative group after NAC had a significantly better prognosis than the other group (p < 0.01). The reduction rate of FDG PET-based quantitative values and visual analysis after NAC demonstrated prognostic potential, especially in PFS.     

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

Purpose

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.

Methods

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.

Results

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.

Conclusion

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.

     

FDG-PET/CT imaging in the management of HIV-associated multicentric Castleman’s disease

Purpose  To evaluate the role of FDG-PET/CT scanning in the management of HIV-associated multicentric Castleman’s disease (MCD) a rare lymphoproliferative disorder associated with infection by human herpesvirus 8 (HHV8). Materials and methods  Nine patients with histologically confirmed MCD underwent fused FDG-PET/CT scans at initial MCD diagnosis (n = 3), at MCD relapse (n = 4), or during remission (n = 2). All seven patients with active MCD had markedly elevated plasma HHV8 viral loads, but the patients in remission had no HHV8 viraemia. The three patients with newly diagnosed MCD were not on antiretroviral therapy at the time of imaging, but the other six were all on fully suppressive antiretroviral regimens. Results  In the seven patients with active MCD (newly diagnosed or relapse) 33/91 lymph node groups (36%) included radiologically enlarged nodes on the CT scan, whilst 57/91 lymph node groups (63%) showed enhanced FDG uptake on the PET scan. In scans from patients in remission, there were no enlarged lymph nodes on the CT scan but 3 lymph nodes (11%) demonstrated enhanced FDG uptake. The median SUV recorded for the seven patients with active MCD was 4.8 (range 2.6–9.3) which was significantly higher than the median value of 2.5 recorded for the patients in remission (Mann-Whitney U test, p = 0.011). Conclusion  Despite the small number of patients, in HIV-positive individuals with active MCD, FDG-PET scans more frequently detected abnormal uptake than CT scans detected enlarged lymph nodes. FDG-PET scanning has a useful role in the management of HIV-associated MCD in selecting appropriate sites for biopsy, and in staging and monitoring these lymphoproliferations.     

Differential diagnosis between 18F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan

Objective  To clarify the difference of ¹⁸F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. Methods  The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg ¹⁸F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%ΔSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis. Results  Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 ± 5.0 vs. 5.9 ± 3.4; P < 0.0001, and 3.0 ± 1.3 vs. 2.8 ± 1.0; P < 0.05, respectively). Early and delayed SUVmax and %ΔSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %ΔSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs. Conclusions  Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.     

Use of FDG-PET in differentiating benign from malignant compression fractures

Objective The objective was to evaluate the use of fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating benign from malignant compression fractures. Patients and methods In a retrospective analysis, we identified 33 patients with 43 compression fractures who underwent FDG-PET. On FDG-PET the uptake pattern was recorded qualitatively and semiquantitatively and fractures were categorized as benign or malignant. Standardized uptake values (SUV) were obtained. MRI, CT, and biopsy results as well as clinical follow-up for 1–3 years served as standards of reference. The Student’s t test was used to determine whether there was a statistically significant difference between the SUV for benign and malignant compression fractures. Results There were 14 malignant and 29 benign compression fractures, including 5 acute benign fractures. On FDG-PET, 5 benign fractures were falsely classified as malignant (false-positive). Three of these patients underwent prior treatment with bone marrow-stimulating agents. There were two false-negative results. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG-PET in differentiating benign from malignant compression fractures were 86%, 83%, 84%, 71%, and 92% respectively. The difference between SUV values of benign and malignant fractures was statistically significant (1.9 ± 0.97 for benign and 3.9 ± 1.52 for malignant fractures, p < 0.001). SUV of benign acute and chronic fractures were not statistically significant. Conclusion Fluorodeoxyglucose positron emission tomography is useful in differentiating benign from malignant compression fractures. Therapy with bone marrow-stimulating agents can mimic malignant involvement.     

Low baseline and subsequent higher aortic abdominal aneurysm FDG uptake are associated with poor sac shrinkage post endovascular repair

Purpose

The growth phases of medically treated abdominal aortic aneurysms (AAA) are frequently associated with an ¹⁸F–fluorodesoxyglucose positron emission tomography (FDG-PET) pattern involving low baseline and subsequent higher FDG uptake. However, the FDG-PET patterns associated with the endovascular aneurysm repair (EVAR) of larger AAA are presently unknown. This study aimed to investigate the relationship between serial AAA FDG uptake measurements, obtained before EVAR and 1 and 6 months post-intervention and subsequent sac shrinkage at 6 months, a well-recognized indicator of successful repair.

Methods

Thirty-three AAA patients referred for EVAR (maximal diameter: 55.4?±?6.0 mm, total volume: 205.7?±?63.0 mL) underwent FDG-PET/computed tomography (CT) before EVAR and at 1 and 6 months thereafter, with the monitoring of AAA volume and of a maximal standardized FDG uptake [SUVmax] averaged between the axial slices encompassing the AAA.

Results

Sac shrinkage was highly variable and could be stratified into three terciles: a first tercile in which shrinkage was absent or very limited (0–29 mL) and a third tercile with pronounced shrinkage (56–165 mL). SUVmax values were relatively low at baseline in the 1st tercile (SUVmax: 1.69?±?0.33), but markedly increased at 6 months (2.42?±?0.69, p?=?0.02 vs. baseline). These SUV max values were by contrast much higher at baseline in the 3rd tercile (SUVmax: 2.53?±?0.83 p?=?0.009 vs. 1st tercile) and stable at 6 months (2.49?±?0.80), while intermediate results were documented in the 2nd tercile. Lastly, the amount of sac shrinkage, expressed in absolute values or in percentages of baseline AAA volumes, was positively correlated with baseline SUVmax (p?=?0.001 for both).

Conclusion

A low pre-EVAR FDG uptake and increased AAA FDG uptake at 6 months are associated with reduced sac shrinkage. This sequential FDG-PET pattern is similar to that already shown to accompany growth phases of medically treated AAA.

     

Myocardial pre-synaptic sympathetic function correlates with glucose uptake in the failing human heart

Purpose We have previously shown that the myocardium of patients with heart failure (HF) is insulin resistant. Chronic β-adrenergic stimulation has been implicated in insulin resistance in cultured cardiomyocytes in vitro, where sustained noradrenaline stimulation inhibited insulin-modulated glucose uptake. As the failing heart is characterized by increased sympathetic drive, we hypothesized that there is a correlation between pre-synaptic sympathetic function and insulin sensitivity in the myocardium of patients with HF. Methods Eight patients (aged 67 ± 7 years) with coronary artery disease and left ventricular dysfunction (ejection fraction 44 ± 10%) underwent function and viability assessment with cardiovascular magnetic resonance. Myocardial glucose utilization (MGU) was measured using positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG). Pre-synaptic noradrenaline re-uptake was measured by calculating [¹¹C]meta-hydroxy-ephedrine (HED) volume of distribution (V _d) with PET. Two groups of healthy volunteers served as controls for the FDG (n = 8, aged 52 ± 4 years, p < 0.01 vs patients) and HED (n = 8, aged 40 ± 6 years, p < 0.01 vs patients) data. Results MGU in patients was reduced in both normal remote (0.44 ± 0.14 μmol·min⁻¹·g⁻¹) and dysfunctional (0.49 ± 0.14 μmol·min⁻¹·g⁻¹) segments compared with controls (0.61 ± 0.7 μmol·min⁻¹·g⁻¹; p < 0.001 vs both). HED V _d was reduced in dysfunctional segments of patients (38.9 ± 21.2 ml·g⁻¹) compared with normal segments (52.2 ± 19.6 ml·g⁻¹) and compared with controls (62.7 ± 11.3 ml·g⁻¹). In patients, regional MGU was correlated with HED V _d. Conclusion The results of this study provide novel evidence of a correlation between cardiac sympathetic function and insulin sensitivity, which may represent one of the mechanisms contributing to insulin resistance in failing human hearts.     

18F-FDG PET for assessment of therapy response and preoperative re-evaluation after neoadjuvant radio-chemotherapy in stage III non-small cell lung cancer

Purpose The aim of this study was to evaluate FDG-PET for assessment of therapy response and for prediction of patient outcome after neo-adjuvant radio-chemotherapy (NARCT) of advanced non-small cell lung cancer (NSCLC). Methods Seventy patients with histologically proven stage III NSCLC underwent FDG-PET investigations before and after NARCT. Changes in FDG uptake and PET findings after completion of NARCT were compared with (1) the histology of tumour samples obtained at surgery or repeat mediastinoscopy, and (2) treatment results in terms of achieved operability and long-term survival. Results The mean average FDG uptake of the primary tumours in the patient group decreased significantly during NARCT (p = 0.004). Sensitivity, specificity and overall accuracy of FDG-PET were 94.5%, 80% and 91%, respectively, for the detection of residual viable primary tumour, and 77%, 68% and 73%, respectively, for the presence of lymph node metastases. A negative PET scan or a reduction in the standardised uptake value (SUV) of more than 80% was the best predictive factor for a favourable outcome of further treatment. Progressive disease according to PET (new tumour manifestations or increasing SUV) was significantly correlated with an unfavourable outcome (p = 0.005). In this subgroup, survival of patients who underwent surgery was not significantly different from survival among those who did not undergo surgery, whereas for the whole patient group, complete tumour resection had a significant influence on outcome. Conclusion FDG-PET is suitable to assess response to NARCT in patients with stage III NSCLC accurately. It was highly predictive for treatment outcome and patient survival. PET may be helpful in improving restaging after NARCT by allowing reliable assessment of residual tumour viability.