La TEP-TDM à la F-Dopa aurait-elle un rôle dans le suivi postopératoire des patients atteints de carcinome médullaire de la thyroïde ? Résultats préliminaires de l’expérience strasbourgeoise et revue de la littérature

Aim

Retrospective study to assess the value of fluorine-18 dihydroxyphenylalanine (¹⁸F-Dopa) positron emission tomography (PET)/computed tomography (CT) in the post-surgical follow-up of patients with history of medullary thyroid carcinoma (MTC) and biological suspicion of disease relapse. A review of the literature was also performed.

Patients and methods

Ten patients (23-71 years) with MTC previously treated by surgery were examined by at least one ¹⁸F-Dopa PET/CT. All patients presented with elevated serum calcitonin (130-9076 ng/l) and/or CEA (1.2-518 ng/ml) levels. 3D whole body PET/CT was performed 45 and 120 minutes after intravenous injection of 4 MBq/kg of ¹⁸F-Dopa. Scintigraphic images were visually interpreted. For quantitative analysis, maximum standardized uptake value (SUV_max) per focus was employed. PET results were compared with histological findings and/or with the results of all other imaging procedures.

Results

Seven patients (70%) had a positive ¹⁸F-Dopa PET/CT. Twenty-five focal tracer accumulations were described. Histopathological confirmation of metastatic disease was obtained in four of the seven patients with pathologic ¹⁸F-Dopa PET/CT. No scintigraphic abnormalities were evidenced in the three other patients, whose conventional morphological imaging procedures were also negatives. Delayed PET/CT examinations didn’t increase sensitivity. No correlation between ¹⁸F-Dopa PET/CT results and both serum calcitonin and CEA levels was achieved.

Conclusion

Our results are in accordance with the existing literature, showing the potential role of ¹⁸F-Dopa PET/CT in the clinical management of patients with history of MTC and biological suspicion of relapse during post-surgical follow-up. Prospective studies including larger patient series are necessary to confirm the future place of ¹⁸F-Dopa PET/CT in follow-up of MTC.     

Réduction des effets de la respiration en imagerie TEP pulmonaire par une acquisition synchronisée à la respiration associée à une TDM en apnée

Respiratory motion causes a spread of lesion uptake over a larger area in Positron Emission Tomography (PET) images for moving structures. When CT images are used for attenuation correction of emission data, this motion may alter the quantization of PET images. We present the clinical results of a respiratory-gated PET processing “CT-based” method, which aims to improve PET-CT coregistration by using an additional breath-hold CT (BH-CT). The CT-based protocol consisted in a 10-min List Mode respiratory-gated PET acquisition, followed by an end-expiration BH-CT acquisition. During these two examinations, the respiratory signal was recorded continuously. Eleven pulmonary lesions were studied. Patients underwent both a standard clinical PET protocol (free breathing) and the CT-based protocol. The respective performances of the CT-based and clinical PET methods were evaluated by comparing the distances between the lesions’ centroids on PET and CT images. SUV_MAX (Standardized Uptake Value) and volume variations were also investigated. The CT-based method showed a significant reduction (p = 0.049) of centroid distances (mean relative change versus standard method: 49%). We also noted a higher SUV_MAX (mean change: 39%). Lesion volumes were significantly lower (p = 0.026) in CT-based PET volumes (mean change: 43%) compared with standard ones. The CT-based method improves PET-CT coregistration of pulmonary lesions. This protocol should lead to more accurate attenuation correction and thus improve SUV measurement.     

The Usefulness of Standardized Uptake Value in Differentiation between Benign and Malignant Thyroid Lesions Detected Incidentally in 18F-FDG PET/CT Examination

Introduction

In the last decade, (18)F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET and PET/CT) has become one of the major diagnostic tools used in oncology. A significant number of patients who undergo this procedure, due to non-thyroidal reasons, present incidental uptake of (¹⁸F-FDG) in the thyroid. The aim of the study was to compare the SUV_max (standardized uptake value) of thyroid focal lesions, which were incidentally found on PET/CT, in relation to the results of thyroid fine-needle aspiration biopsy (FNAB) and/or histopathological evaluation.

Materials and Methods

Patients referred for PET/CT examination, due to non-thyroidal illness, presented focal ¹⁸F-FDG uptake in the thyroid and were advised to undergo ultrasonography (US), hormonal evaluation, FNAB and/or total thyroidectomy at our institution.

Results

6614 PET/CT examinations performed in 5520 patients were analyzed. Of the 122 patients with focal thyroid ¹⁸F-FDG activity, 82 patients (67.2%) underwent further thyroid evaluation using FNAB. Benign lesions were diagnosed in 46 patients, malignant - in 19 patients (confirmed by post-surgical histopathology), while 17 patients had inconclusive results of cytological assessment. Mean SUV_max of benign lesions was 3.2±2.8 (median = 2.4), while the mean SUV_max value for malignant lesions was 7.1±8.2 (median = 3.5). The risk of malignancy was 16.7% for lesions with a SUV_max under 3, 43.8% for lesions with a SUV_max between 3 and 6, and 54.6% for lesions with a SUV_max over 6. In the group of malignant lesions, a positive correlation between the lesion’s diameter and SUV_max was observed (p = 0.03, r = 0.57).

Conclusions

Subjects with incidental focal uptake of ¹⁸F-FDG in thyroid are at a high risk of thyroid malignancy. A high value of SUV_max further increases the risk of malignancy, indicating the necessity for further cytological or histological evaluation. However, as SUV_max correlated with the diameter of malignant lesions, small lesions with focal uptake of ¹⁸F-FDG should be interpreted cautiously.     

Identification of Metabolic Biomarkers Using Serial 18F–FDG PET/CT for Prediction of Recurrence in Advanced Epithelial Ovarian Cancer

PURPOSE. To evaluate the prognostic value of metabolic parameters derived from serial ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with advanced epithelial ovarian cancer (EOC). METHODS. Thirteen patients with advanced EOC who received surgical staging and adjuvant platinum-based combination chemotherapy were prospectively enrolled. ¹⁸F–FDG PET/CT was performed before and after the surgical staging, and after third cycle of chemotherapy. Tumor glucose metabolism at baseline and its change after operation and third cycle of chemotherapy such as changes of maximum standardized uptake values (ΔSUV_max) via ¹⁸F–FDG PET/CT were measured, and assessed regarding their ability to predict recurrence. RESULTS. Median duration of progression-free survival (PFS) was 25 months (range, 13–34), and although optimal debulking was performed in 10 patients, 5 (38.5%) patients experienced recurrence. Univariate analyses showed significant associations between recurrence and low ΔSUV_max after surgical staging, and low SUV_max change after third cycle of chemotherapy. Multivariate analysis identified low ΔSUV_max after third cycle of chemotherapy as an independent risk factor for recurrence (P = .047, hazard ratio (HR) 16.375, 95% CI 1.041–257.536). Kaplan–Meier survival curves showed that PFS significantly differed in groups categorized based on ΔSUV_max after chemotherapy (P = .001, log-rank test). CONCLUSIONS. ¹⁸F–FDG PET/CT allows for prediction of treatment response by the level of FDG uptake in terms of SUV at baseline and after chemotherapy. The metabolic response measured as ΔSUV_max after third cycle of chemotherapy appears to be promising predictor of recurrence in patients with advanced EOC.     

Effects of Reusing Baseline Volumes of Interest by Applying (Non-)Rigid Image Registration on Positron Emission Tomography Response Assessments

Objectives

Reusing baseline volumes of interest (VOI) by applying non-rigid and to some extent (local) rigid image registration showed good test-retest variability similar to delineating VOI on both scans individually. The aim of the present study was to compare response assessments and classifications based on various types of image registration with those based on (semi)-automatic tumour delineation.

Methods

Baseline (n = 13), early (n = 12) and late (n = 9) response (after one and three cycles of treatment, respectively) whole body [¹⁸F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (PET/CT) scans were acquired in subjects with advanced gastrointestinal malignancies. Lesions were identified for early and late response scans. VOI were drawn independently on all scans using an adaptive 50% threshold method (A50). In addition, various types of (non-)rigid image registration were applied to PET and/or CT images, after which baseline VOI were projected onto response scans. Response was classified using PET Response Criteria in Solid Tumors for maximum standardized uptake value (SUV_max), average SUV (SUV_mean), peak SUV (SUV_peak), metabolically active tumour volume (MATV), total lesion glycolysis (TLG) and the area under a cumulative SUV-volume histogram curve (AUC).

Results

Non-rigid PET-based registration and non-rigid CT-based registration followed by non-rigid PET-based registration (CTPET) did not show differences in response classifications compared to A50 for SUV_max and SUV_peak,, however, differences were observed for MATV, SUV_mean, TLG and AUC. For the latter, these registrations demonstrated a poorer performance for small lung lesions (<2.8 ml), whereas A50 showed a poorer performance when another area with high uptake was close to the target lesion. All methods were affected by lesions with very heterogeneous tracer uptake.

Conclusions

Non-rigid PET- and CTPET-based image registrations may be used to classify response based on SUV_max and SUV_peak. For other quantitative measures future studies should assess which method is valid for response evaluations by correlating with survival data.     

Valeur pronostique de la TEP/TDM dans le bilan initial du cancer du col utérin : SUVmax de la tumeur primitive et stadification ganglionnaire

PurposeWe investigated the prognostic significance of F-18 fluorodeoxyglucose (FDG) uptake measured as maximum Standardized Uptake Value (SUV_max) in primary tumor by positron emission tomography/computed tomography (PET/CT) in cervical cancer. The secondary objective was to determine the accuracy of the PET/CT for detecting pelvic lymph node (PLN) and para-aortic lymph node (PALN) metastases.MethodsThis retrospective study included 49 consecutive patients with stage IB1 to IVB cervical cancer. Univariate analysis was performed to determine the relationships between SUV_max value and pathological prognostics factors. Survival was estimated by Kaplan-Meier method. The gold standard of LN metastases was histologic.ResultsA significant difference in SUV_max was observed between stage I and stage II, stage I and stage IV and tumor size ≤ 4 cm and > 4 cm (P = 0.0001). There was a significant correlation between the SUV_max and tumor maximal size (r = 0.597) (P < 0.0001). PLN metastasis was found to be predictive of progression-free survival (P = 0.0007). The negative predictive value (NPV) of the PET/CT for PALN was 100% for locally advanced cervical carcinoma in 24 patients. The specificity and NPV of the PET/CT for PLN in eight early-stage cervical cancer were 100% and 87.5% (7/8) respectively. The PET/CT false-negative PLN measured less than 2 mm.ConclusionOur results demonstrate a correlation between SUV_max and tumor maximal size, which represents an indicator of tumor aggressiveness. PET/CT is effective to predict the absence of PALN in locally advanced cervical carcinoma. PET/CT is not sufficient to predict PLN in early-stage cancer without lymphadenectomy.     

Performance comparison of two resolution modeling PET reconstruction algorithms in terms of physical figures of merit used in quantitative imaging

PurposeResolution modeling (RM) of PET systems has been introduced in iterative reconstruction algorithms for oncologic PET. The RM recovers the loss of resolution and reduces the associated partial volume effect. While these methods improved the observer performance, particularly in the detection of small and faint lesions, their impact on quantification accuracy still requires thorough investigation. The aim of this study was to characterize the performances of the RM algorithms under controlled conditions simulating a typical ¹⁸F-FDG oncologic study, using an anthropomorphic phantom and selected physical figures of merit, used for image quantification.MethodsMeasurements were performed on Biograph HiREZ (B_HiREZ) and Discovery 710 (D_710) PET/CT scanners and reconstructions were performed using the standard iterative reconstructions and the RM algorithms associated to each scanner: TrueX and SharpIR, respectively.ResultsRM determined a significant improvement in contrast recovery for small targets (≤17 mm diameter) only for the D_710 scanner. The maximum standardized uptake value (SUV_max) increased when RM was applied using both scanners. The SUV_max of small targets was on average lower with the B_HiREZ than with the D_710. Sharp IR improved the accuracy of SUV_max determination, whilst TrueX showed an overestimation of SUV_max for sphere dimensions greater than 22 mm. The goodness of fit of adaptive threshold algorithms worsened significantly when RM algorithms were employed for both scanners.ConclusionsDifferences in general quantitative performance were observed for the PET scanners analyzed. Segmentation of PET images using adaptive threshold algorithms should not be undertaken in conjunction with RM reconstructions.     

Respiratory Motion Reduction in PET/CT Using Abdominal Compression for Lung Cancer Patients

Purpose

Respiratory motion causes substantial artifacts in reconstructed PET images when using helical CT as the attenuation map in PET/CT imaging. In this study, we aimed to reduce the respiratory artifacts in PET/CT images of patients with lung tumors using an abdominal compression device.

Methods

Twelve patients with lung cancer located in the middle or lower lobe of the lung were recruited. The patients were injected with 370 MBq of ¹⁸F-FDG. During PET, the patients assumed two bed positions for 1.5 min/bed. After conducting free-breathing imaging, we obtained images of the patients with abdominal compression by applying the same setup used in the free-breathing scan. The differences in the standardized uptake value (SUV)_max, SUV_mean, tumor volume, and the centroid of the tumors between PET and various CT schemes were measured.

Results

The SUV_max and SUV_mean derived from PET/CT imaging using an abdominal compression device increased for all the lesions, compared with those obtained using the conventional approach. The percentage increases were 18.1% ±14% and 17% ±16.8% for SUV_max and SUV_mean, respectively. PET/CT imaging combined with abdominal compression generally reduced the tumor mismatch between CT and the corresponding attenuation corrected PET images, with an average decrease of 1.9±1.7 mm over all the cases.

Conclusions

PET/CT imaging combined with abdominal compression reduces respiratory artifacts and PET/CT misregistration, and enhances quantitative SUV in tumor. Abdominal compression is easy to set up and is an effective method used in PET/CT imaging for clinical oncology, especially in the thoracic region.     

Infection de prothèse vasculaire : TEP-FDG vs scintigraphie aux leucocytes marqués (planaires et TEMP/TDM)

Vascular prosthesis infection is an uncommon but life-threatening complication. Its diagnosis is difficult to establish especially due to the low specificity of computed tomography (CT). The aim of this preliminary study was to compare the diagnostic value of positron emission tomography with¹⁸FDG (¹⁸FDG-PET) and ^99mTc-HMPAO-labeled leukocytes scintigraphy in this indication. ¹⁸FDG-PET/CT and ^99mTc-HMPAO-labeled leukocytes scintigraphy (planar at 6th and 24th hours after injection + SPECT/CT at the 6th hour) were prospectively performed in 11 patients (total of 22 vascular prosthesis with 14 clinical suspicions of infection). Both scans were retrospectively and blindly assessed by two independent nuclear medicine physicians. Interpretation was based on visual analysis. The gold standard was bacteriology findings or clinical follow-up greater than 6 months. Eight prostheses were considered as infected. PET found eight true-positive and one false-positive. Scintigraphy found eight true-positive and no false-positive. A focal or heterogeneous FDG-uptake higher or equal than hepatic uptake was considered as positive in PET. A focal prosthetic activity, stable or increased at the 24th hour was considered as positive in labeled leukocyte scintigraphy. SPECT/CT gave accurate anatomic localization and differentiated clearly infections of soft tissues from those of prostheses. ¹⁸FDG-PET could be performed in first-line in suspicion of vascular prosthesis infection. In litigious cases, a^99mTc-HMPAO-labeled leukocytes scintigraphy in association with SPECT/CT could bring additional arguments for infection diagnosis.     

Correlations between Functional Imaging Markers Derived from PET/CT and Diffusion-Weighted MRI in Diffuse Large B-Cell Lymphoma and Follicular Lymphoma

Objectives

To investigate the correlations between functional imaging markers derived from positron emission tomography/computed tomography (PET/CT) and diffusion-weighted magnetic resonance imaging (DWI) in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Further to compare the usefulness of these tumor markers in differentiating diagnosis of the two common types of Non-Hodgkin''s lymphoma (NHL).

Materials and Methods

Thirty-four consecutive pre-therapy adult patients with proven NHL (23 DLBCL and 11 FL) underwent PET/CT and MRI examinations and laboratory tests. The maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), and metabolic tumor burden (MTB) were determined from the PET/CT images. DWI was performed in addition to conventional MRI sequences using two b values (0 and 800 s/mm²). The minimum and mean apparent diffusion coefficient (ADC_min and ADC_mean) were measured on the parametric ADC maps.

Results

The SUV_max correlated inversely with the ADC_min (r = −0.35, p<0.05). The ADC_min, ADC_mean, serum thymidine kinase (TK), Beta 2-microglobulin (B2m), lactate dehydrogenase (LD), and C-reactive protein (CRP) correlated with both whole-body MTV and whole-body MTB (p<0.05 or 0.01). The SUV_max, TK, LD, and CRP were significantly higher in the DLBCL group than in the FL group. Receiver operating characteristic curve analysis showed that they were reasonable predictors in differentiating DLBCL from FL.

Conclusions

The functional imaging markers determined from PET/CT and DWI are associated, and the SUV_max is superior to the ADC_min in differentiating DLBCL from FL. All the measured serum markers are associated with functional imaging markers. Serum LD, TK, and CRP are useful in differentiating DLBCL from FL.     

Detection of Vulnerable Atherosclerotic Plaque and Prediction of Thrombosis Events in a Rabbit Model Using 18F-FDG -PET/CT

Background

Detection of vulnerable plaques could be clinically significant in the prevention of cardiovascular events. We aimed to compare Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) uptake in vulnerable and stable plaques, and investigate the feasibility of predicting thrombosis events using Positron Emission Tomography/Computed Tomography (PET/CT) angiography.

Methods

Atherosclerosis was induced in 23 male New Zealand white rabbits. The rabbits underwent pharmacological triggering to induce thrombosis. A pre-triggered PET/CTA scan and a post-triggered PET/CTA scan were respectively performed. ¹⁸F-FDG uptake by the aorta was expressed as maximal standardized uptake value (SUV_max) and mean SUV (SUV_mean). SUVs were measured on serial 7.5 mm arterial segments.

Results

Thrombosis was identified in 15 of 23 rabbits. The pre-triggered SUV_mean and SUV_max were 0.768±0.111 and 0.804±0.120, respectively, in the arterial segments with stable plaque, and 1.097±0.189 and 1.229±0.290, respectively, in the arterial segments with vulnerable plaque (P<0.001, respectively). The post-triggered SUV_mean and SUV_max were 0.849±0.167 and 0.906±0.191, respectively in the arterial segments without thrombosis, and 1.152±0.258 and 1.294±0.313, respectively in the arterial segments with thrombosis (P<0.001, respectively). The values of SUV_mean in the pre-triggered arterial segments were used to plot a receiver operating characteristic curve (ROC) for predicting thrombosis events. Area under the curve (AUC) was 0.898. Maximal sensitivity and specificity (75.4% and 88.5%, respectively) were obtained when SUV_mean was 0.882.

Conclusions

Vulnerable and stable plaques can be distinguished by quantitative analysis of ¹⁸F-FDG uptake in the arterial segments in this rabbit model. PET/CT may be used for predicting thrombosis events and risk-stratification in patients with atherosclerotic disease.     

18F-FDG Micro PET/CT imaging to evaluate the effect of BRCA1 knockdown on MDA-MB231 breast cancer cell radiosensitivity

ObjectiveRadioresistance of tumor cells is a major factor associated with failure of radiotherapy (RT). This study aimed to investigate the effect of BRCA1 knockdown on MDA-MB231 breast cancer cell radiosensitivity.Materials and methodsShort hairpin RNA (shRNA) was used to knockdown BRCA1 gene in MDA-MB231 cells. Cell viability and proliferative capacity were assessed by CCK-8 and colony formation assays, respectively. We established xenograft models in nude mice to evaluate tumor volume and tumor weight. The mice were imaged by ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) before and after RT to evaluate changes in maximum standardized uptake value (SUV_max) and tumor SUV_max/muscle SUV_max (TMR). Changes in HIF-1α, Glut-1 and Ki-67 were analyzed and the correlation between ¹⁸F-FDG uptake and tumor biology was analyzed.ResultsCompared with the control cells, RT significantly reduced cell viability and colony formation capacity in cells with the BRCA1 gene knockdown. In vivo assays showed that there was obvious delay in the tumor growth in the shBRCA1+RT group compared with the control group. ¹⁸F-FDG Micro PET/CT indicated a reduction in glucose metabolism in the shBRCA1+RT group, with statistically significant differences in both the SUV_max and TMR. The data showed the expression of HIF-1α, Glut-1 and Ki-67 was downregulated in the shBRCA1+RT group, and both SUVmax and TMR had significant correlation with tumor biology.ConclusionThese results demonstrated that BRCA1 knockdown improves the sensitivity of MDA-MB231 breast cancer cells to RT. In addition, ¹⁸F-FDG PET/CT imaging allows non-invasive analysis of tumor biology and assessment of radiosensitivity.     

Valeur pronostique de la TEP au F-FDG dans le bilan d’extension initial du cancer de l’œsophage traité par radiochimiothérapie exclusive

The aim of this retrospective study was to investigate the prognostic significance of initial FDG-PET in patients with newly diagnosed oesophageal carcinoma before exclusive radiochemotherapy. FDG-PET was performed in 29 patients with newly diagnosed oesophageal carcinoma before radiochemotherapy. Maximum standardized uptake value (SUV_max) was determined in each primary lesion and the presence of one or more PET-positive lymph nodes was recorded. Primary tumour volume and tumour length were assessed using two different thresholds for tumour delimitation: SUV = 2.5 and SUV = 40% of SUV_max. Patients were followed clinically during at least 1 year after initial FDG-PET. The median follow-up was 35 months (IC 95% = 26-41 months). Thirteen patients (45%) died during the follow-up. By univariate logistic regression analysis, the SUV_max of primary tumour and the presence of one or more positive lymph nodes were significantly associated with the overall survival. In contrast, no significant difference of prognosis was observed concerning age, sex, tumour cell type, primary site, clinical stage, primary tumour volume and length. Multivariate analysis was not performed due to the too small number of events. FDG-PET provides early prognostic informations in oesophageal carcinoma treated by radiochemotherapy.     

Correlation of Standardized Uptake Value and Apparent Diffusion Coefficient in Integrated Whole-Body PET/MRI of Primary and Recurrent Cervical Cancer

Background

To evaluate a potential correlation of the maximum standard uptake value (SUV_max) and the minimum apparent diffusion coefficient (ADC_min) in primary and recurrent cervical cancer based on integrated PET/MRI examinations.

Methods

19 consecutive patients (mean age 51.6 years; range 30–72 years) with histopathologically confirmed primary cervical cancer (n = 9) or suspected tumor recurrence (n = 10) were prospectively enrolled for an integrated PET/MRI examination. Two radiologists performed a consensus reading in random order, using a dedicated post-processing software. Polygonal regions of interest (ROI) covering the entire tumor lesions were drawn into PET/MR images to assess SUV_max and into ADC parameter maps to determine ADC_min values. Pearson’s correlation coefficients were calculated to assess a potential correlation between the mean values of ADC_min and SUV_max.

Results

In 15 out of 19 patients cervical cancer lesions (n = 12) or lymph node metastases (n = 42) were detected. Mean SUV_max (12.5±6.5) and ADC_min (644.5±179.7×10⁻⁵ mm²/s) values for all assessed tumor lesions showed a significant but weak inverse correlation (R = −0.342, p<0.05). When subdivided in primary and recurrent tumors, primary tumors and associated primary lymph node metastases revealed a significant and strong inverse correlation between SUV_max and ADC_min (R = −0.692, p<0.001), whereas recurrent cancer lesions did not show a significant correlation.

Conclusions

These initial results of this emerging hybrid imaging technique demonstrate the high diagnostic potential of simultaneous PET/MR imaging for the assessment of functional biomarkers, revealing a significant and strong correlation of tumor metabolism and higher cellularity in cervical cancer lesions.     

Correlation of the Apparent Diffusion Coefficient (ADC) with the Standardized Uptake Value (SUV) in Lymph Node Metastases of Non-Small Cell Lung Cancer (NSCLC) Patients Using Hybrid 18F-FDG PET/MRI

ObjectiveTo compare the apparent diffusion coefficient (ADC) in lymph node metastases of non-small cell lung cancer (NSCLC) patients with standardized uptake values (SUV) derived from combined 18F-fluoro-deoxy-glucose-positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI).ResultsA total of 146 suspicious lymph nodes were found in 25 patients. One hundred lymph nodes were eligible for final analysis. Ninety-one lymph nodes were classified as malignant and 9 as benign according to the reference standard. In malignant lesions, mean SUV_max was 9.1 ± 3.8 and mean SUV_mean was 6.0 ± 2.5 while mean ADC_mean was 877.0 ± 128.6 x10^-5 mm²/s in PET/MRI. For all malignant lymph nodes, a weak, inverse correlation between SUV_max and ADC_mean as well as SUV_mean and ADC_mean (r = -0.30, p<0.05 and r = -0.36, p<0.05) existed.ConclusionThe present data show a weak inverse correlation between increased glucose-metabolism and cellularity in lymph node metastases of NSCLC patients. 18F-FDG-PET and DWI thus may offer complementary information for the evaluation of treatment response in lymph node metastases of NSCLC.     

Serum VEGF levels as predictive marker of bisphosphonate-related osteonecrosis of the jaw

This study was aimed to investigate the significance of ¹⁸F-FDG PET/CT in secondary hemophagocytic lymphohistiocytosis (sHLH) patients. A total of 18 patients received ¹⁸F-FDG PET/CT scan at initial diagnosis. All patients (18/18) had at least 3 organs involved, with increased FDG metabolism in different degrees. Fifteen cases (15/18) had definite underlying diseases, including infections (IAHLH), rheumatosis (RAHLH), or malignancy (MAHLH). The SUV_max of patients in MAHLH group was significantly higher than patients in IAHLH group or RAHLH group (P?=?0.015, P?=?0.045). Furthermore, the SUV_max of patients in IAHLH group was significantly higher than patients of RAHLH group (P?=?0.043). Therefore, we concluded that ¹⁸F-FDG PET/CT may especially play important role in differential diagnosis of sHLH.     

Evaluation of the Metabolic Response to Cyclopamine Therapy in Pancreatic Cancer Xenografts Using a Clinical PET-CT System

OBJECTIVES: We analyzed the effects of anti-hedgehog signaling on the ¹⁸F-FDG uptake of pancreatic cancer xenografts (PCXs) using a clinically implemented positron emission tomography (PET)-computer tomography (CT) scanner with high-resolution reconstruction. METHODS: PCXs from two pancreatic cancer cell lines were developed subcutaneously in nude mice and injected intraperitoneally with a low dose of cyclopamine for 1 week. ¹⁸F-FDG PET-CT was performed using a new-generation clinical PET-CT scanner with minor modifications of the scanning protocol to adapt for small-animal imaging. The data set was reconstructed and quantified using a three-dimensional workstation. RESULTS: MiaPaCa-2 cells, which respond to cyclopamine, showed decreased ¹⁸F-FDG uptake without a change in tumor size. For hip tumors, the maximum standardized uptake value (SUV_max) was reduced by -24.5 ± 9.2%, the average SUV (SUV_avg) by -33.5 ± 7.0%, and the minimum SUV (SUV_min) by -54.4 ± 11.5% (P < .05). For shoulder tumors, SUV_max was reduced by -14.7 ± 7.5%, SUV_avg by -12.6 ± 6.3, and SUV_min by -30.3 ± 16.7% (P < .05). Capan-1 cells, which do not respond to cyclopamine, did not show significant SUV changes. CONCLUSIONS: The new generations of clinically implemented PET-CT scanners with high-resolution reconstruction detect a minimal response of PCX to low-dose short-term cyclopamine therapy without changes in tumor size and offer potential for preclinical translational imaging.     

Découverte fortuite de fixations colorectales focales du FDG en TEP/TDM : corrélation aux données de la coloscopie

PurposeFDG-PET is an established tool for the diagnosis of recurrent or metastatic colorectal carcinoma. Several case series suggest that FDG-PET often detects incidental adenomatous polyps or colorectal adenocarcinomas. The aim of this study was to correlate unexpected colorectal foci of FDG uptake to pathology findings after systematic colonoscopy.Patients and methodsWe reviewed the records of 3541 patients who underwent FDG PET/CT in our institution over a 30-month period for the assessment of a known or suspected malignancy. In 85 of them, incidental, nodular shaped and well-circumscribed foci of abnormal uptake were identified in the area of the colon or rectum. Patients with segmental or diffuse abnormal colorectal uptake were excluded, as well as patients with known benign or malignant colorectal disease. Colonoscopy and complete pathology report was available in 29 patients. Maximal standardized uptake value (SUV_max) was measured in all lesions.ResultsUnexpected colorectal foci of FDG uptake were associated with colonoscopic abnormalities in 23 patients (true positive rate: 79 %). Adenocarcinomas were found in six patients (SUV_max = 7.3 ± 2.6), tubulous adenomas in four patients (SUV_max = 7.3 ± 4.9) and tubulovillous adenomas in 12 patients (SUV_max = 4.2 ± 1.1). Hyperplasic polyps with no sign of dysplasia were found in the last patient (SUV_max = 3.3). Concomitant CT abnormalities were found on PET/CT fusion in eight patients and consisted of wall thickening (n = 5) or nodular mass (n = 3). Conversely, PET was falsely positive in six patients (21 %), with no concomitant CT abnormalities and no abnormal findings at endoscopy (SUV_max = 6.2 ± 2.8, no significant difference with true positive lesions).ConclusionOur findings emphasize the need to perform a colonoscopy in front of incidental nodular colorectal foci of FDG uptake because malignant or pre-malignant neoplasms, which are not clinically apparent, are found in more than three-quarter of cases.     

Accuracy of target delineation by positron emission tomography-based auto-segmentation methods after deformable image registration: A phantom study

PurposeDiagnostic positron emission tomography and computed tomography (PET/CT) images can be fused to the planning CT images by a deformable image registration (DIR). The aim of this study was to evaluate the standardized uptake value (SUV) and target delineation on deformed PET images.MethodsWe used a cylindrical phantom and removable inserts of four spheres (16–38 mm in diameter) and three ellipsoids with a volume equal to the 38-mm-diameter sphere (S38) in each. S38 was filled with 18F-fluorodeoxyglucose activity, and then PET/CT images were acquired. The contours of S38 were generated using original PET images by PET auto-segmentation (PET-AS) methods of (1) SUV2.5, (2) 40% of maximum SUV (SUV40%max), and (3) gradient-based (GB), and were deformed to the other inserts by DIR. We compared the volumes and the SUV_max with the generated contours using the deformed PET images.ResultsThe SUV_max was slightly decreased by DIR; the mean absolute difference was −0.10 ± 0.04. For SUV2.5 and SUV40%max, the differences in S38 volumes between the original and deformed PET images were less than 5%, regardless of deformation type. For the GB, the contoured volumes obtained from deformed PET images were larger than those of the original PET images for the deformation type of ellipsoids. When the S38 was deformed to the 16-mm-diameter sphere, the maximum volume difference was −22.8%.ConclusionsAlthough SUV fluctuations by DIR were negligible, the target delineation on deformed PET images by the GB should be carefully considered owing to the distortion of intensity profiles.