SUV Values Research Articles

Post-heart transplantation lymphoproliferative diseases (PTLDs) and the diagnostic role of [18f] FDG-PET/CT

The incidence of cancer is higher in transplant patients than in the normal population, mostly due to the assumption of immunosuppressants able to reduce the possibility of rejection. In addition, immunocompromised patients have a greater susceptibility to EBV, HPV and HIV, infectious agents that by themselves may favor the onset of malignancies. Post-transplant lymphoproliferative diseases (PLDs) are among the most frequent neoplasms in transplant patients which like other aggressive neoplasms may be identified by the [18f] fluoro-D-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). We evaluated the clinical use of FDG-PET/CT in detecting PTLDs and other neoplasms performed at the lowest clinical or laboratory suspicion of malignancy in 127 consecutive subjects who underwent heart transplantation. A SUV>4 more confirmed the suspect of malignancy and induced us to further investigations. Of the 127 transplant subjects who underwent FDG-PET/CT, 64 showed a SUV value >4. Of these 64, 8 had PTLDs, 49 other neoplasms (urinary tract tumors, thyroid cancer, HPV cancer related, Kaposi' sarcoma and EBV related head and neck neoplasms) and 7 patients with chronic non-neoplastic inflammatory diseases. In the present study, FDG-PET/CT examination was of great use for an early identification and for an early treatment of PTLDs and other neoplasms.

Importance of attenuation correction in PET/MR image quantification: Methods and applications

The generation of accurate attenuation correction (AC) maps is a basic step to allow for quantitative PET/MR imaging. However, generating MR-based AC maps is a challenge because there is no direct relationship between the PET attenuation coefficients (μ) and the intensity of the MR signal, contrary to what happens with the intensity of CT images. In fact, ignoring the bone causes a distorted and biased distribution of the calculated SUV values. To solve this problem, several MR-based AC methods have been proposed in the literature. In this paper we describe how these methods work, and the challenge they faced to translate into full body applications. Currently, in research environments, the accuracy of AC methods is no longer a limiting factor to solve in order to carry out quantitative in vivo molecular imaging studies. However, many of these methods present a series of limitations for their real implementation in the clinical practice due to insufficient clinical validation and the difficulty of their implementation in a real environment (as described in the examples of clinical applications). Thus, we need the PET/MR community to work on the standardization of the use and assessment of different AC methods. In this scenario, the opening and access by vendors to the implementation of new AC methods in their PET/MR scanners plays a crucial role.

Importancia de la corrección de atenuación en la cuantificación de imagen PET/RM: métodos y aplicaciones

The generation of accurate attenuation correction (AC) maps is a basic step to allow for quantitative PET/MR imaging. However, generating MR-based AC maps is a challenge because there is no direct relationship between the PET attenuation coefficients (μ) and the intensity of the MR signal, contrary to what happens with the intensity of CT images. In fact, ignoring the bone causes a distorted and biased distribution of the calculated SUV values. To solve this problem, several MR-based AC methods have been proposed in the literature. In this paper we describe how these methods work, and the challenge they faced to translate into full body applications. Currently, in research environments, the accuracy of AC methods is no longer a limiting factor to solve in order to carry out quantitative in vivo molecular imaging studies. However, many of these methods present a series of limitations for their real implementation in the clinical practice due to insufficient clinical validation and the difficulty of their implementation in a real environment (as described in the examples of clinical applications). Thus, we need the PET/MR community to work on the standardization of the use and assessment of different AC methods. In this scenario, the opening and access by vendors to the implementation of new AC methods in their PET/MR scanners plays a crucial role.

Prognostic value of pretreatment tumor-to-blood standardized uptake ratio (SUR) in rectal cancer.

The prognostic value of SUV on pretreatment F-18 FDG PET/CT imaging in patients with rectal cancer is a matter of debate. SUR is of prognostic value for survival in different cancers. In this study, we aimed to examine the potential prognostic value of SUR and other parameters in pretreatment F-18 FDG PET/CT for non-metastatic rectal cancer. One hundred four non-metastatic rectal cancer patients who underwent pretreatment PET/CT between March 2012 and January 2018 were included in the study. Firstly, SUVmax, SUVmean, MTV, and TLG were calculated semi-automatically at the workstation. SUR was calculated as the ratio of tumor SUVmax to thoracic aorta blood SUVmean. Univariate Cox regression and Kaplan-Meier analysis were used to evaluate overall survival (OS), progression free survival (PFS), and local recurrence (LR). Then, multivariate Cox regression analysis, which included the parameters that were significant in the univariate analysis, was performed. Multivariate Cox regression analysis revealed that SUR was a prognostic factor for PFS. Age and T stage were prognostic factors for both OS and PFS. MTV was found to be independent risk factors for OS. In our study, SUR was the only F-18 FDG PET/CT parameter found to be significant for PFS. The development of new parameters can increase the prognostic value of F-18 FDG PET/CT.

The Relationship of SUV Value in PET-CT with Tumor Differentiation and Tumor Markers in Gastric Cancer.

We aimed to investigate the relationship between the use of fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT), maximized standardized uptake value (SUVmax) values of tumors, and tumor differentiation and tumor markers during the initial staging of patients with gastric cancer. The study included 50 patients (14 women and 36 men; mean age: 63±11 years; age range: 31-80 years) who had undergone initial staging with FDG-PET/CT after the diagnosis of gastric cancer with endoscopic biopsy between January and June 2013. Serum alpha fetoprotein (AFP), carcinogenic antigen 19-9 (CA 19.9), carcinoembryonic antigen (CEA), and C-reactive protein (CRP) levels were measured in patients prior to imaging. PET/CT images were evaluated for primary tumors, locoregional spread, and distant organ metastases, and classified by tumor-node-metastasis staging. Semiquantitative data were collected by SUVmax measurements in pathological regions of involvement. Data were analyzed statistically. FDG-PET/CT showed primary gastric cancer with a sensitivity of 87%. Imaging findings were normal in 3 patients (1/3; mucinous adenocarcinoma, 2/3; signet-ring cell adenocarcinoma). With FDG-PET/CT, 3/50 patients were classified into Stage 1B, 3/50 patients into Stage 2, 5/50 patients into Stage 3A, 5/50 patients into Stage 3B, 5/50 patients into 3C and 29/50 patients into Stage 4. The mean SUVmax was calculated as 11.35±4.3 (poorly differentiated adenocarcinoma: 5.4±1.7; moderately differentiated adenocarcinoma: 10.3±4.8) for the primary tumor and 14.9±6.3 for tumor metastasis. A positive correlation was evident between the measured SUVmax and stage and the grade of primary tumor (p<0.05). While the relationship between SUVmax and levels of serum AFP and CRP was statistically significant (p<0.05), the relationship between SUVmax and levels of serum CA 19-9 and CEA was not statistically significant (p>0.05). The SUVmax of primary tumors was associated with the degree of differentiation of primary tumors and the biochemical tumor markers CRP and AFP. The fact that SUVmax of primary tumors is high supplies clues about the presence of the factors affecting prognosis of the disease.

Usefulness of Hybrid PET/MRI in Clinical Evaluation of Head and Neck Cancer Patients.

(1) Background: The novel hybrid of positron emission tomography/magnetic resonance (PET/MR) examination has been introduced to clinical practice. The aim of our study was to evaluate PET/MR usefulness in preoperative staging of head and neck cancer (HNC) patients (pts); (2) Methods: Thirty eight pts underwent both computed tomography (CT) and PET/MR examination, of whom 21 pts underwent surgical treatment as first-line therapy and were further included in the present study. Postsurgical tissue material was subjected to routine histopathological (HP) examination with additional evaluation of p16, human papillomavirus (HPV), Epstein-Barr virus (EBV) and Ki67 status. Agreement of clinical and pathological T staging, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of CT and PET/MR in metastatic lymph nodes detection were defined. The verification of dependences between standardized uptake value (SUV value), tumor geometrical parameters, number of metastatic lymph nodes in PET/MR and CT, biochemical parameters, Ki67 index, p16, HPV and EBV status was made with statistical analysis of obtained results; (3) Results: PET/MR is characterized by better agreement in T staging, higher specificity, sensitivity, PPV and NPV of lymph nodes evaluation than CT imaging. Significant correlations were observed between SUVmax and maximal tumor diameter from PET/MR, between SUVmean and CT tumor volume, PET/MR tumor volume, maximal tumor diameter assessed in PET/MR. Other correlations were weak and insignificant; (4) Conclusions: Hybrid PET/MR imaging is useful in preoperative staging of HNC. Further studies are needed.

Relationship between the Size and Location of the Mass and Hilar and Mediastinal Lymph Node Metastasis in Early and Locally Advanced Non-small Cell Lung Cancer.

To determine whether there is a relationship between the size and location of the mass and lymph node metastasis in non-small cell lung cancer. Observational study. Department of Medical Oncology of Trakya University, from November 2013 to November 2018. Records of 112 patients, who were followed up for non-small cell lung cancer, were retrospectively reviewed. Patients with distant organ metastasis (M1) and distant lymph node metastasis (N3), a previous history of malignancy, synchronous or metachronous tumors, and those for whom required data could not be obtained were excluded. Lymph nodes were evaluated according to pathology reports in patients undergoing invasive procedures. In patients without invasive procedures, lymph node larger than 1 cm in thorax CT, SUV above 2.5 in PET, and acceptance of metastasis at the Oncology Council was considered decisive. Diameter of the tumor, the shortest distance between the tumor and the mediastinum, the shortest distance between the tumor and the hilum, and the diameters of the largest mediastinal or hilar lymph nodes were measured from the thoracic computed tomography (CT) taken at the time of the diagnosis. The relationship between these values and lymph node metastasis was statistically evaluated. Upon consideration of thoracic CT measurements, lymph node metastasis was found to have a statistically significant relationship with tumors with a large diameter (>55 mm) (p<0.001), tumors close to the mediastinum (<7 mm) (p=0.003), and tumors close to the hilum (<60 mm) (p=0.045). The evaluation of the distinctiveness of markers in diagnosis through ROC analysis showed AUC of 0.70 (p<0.001) for the largest tumor diameter, and the risk of lymph node metastasis was higher for lesions above 55 mm. In thorax CT, Large tumor size, tumor close to mediastinum, tumor close to hilum, large lymph node, and high SUV value of lymph node in PET-CT are associated with increased chances of metastasis.

Evaluation of non-Gaussian model-based diffusion-weighted imaging in oral squamous cell carcinoma: comparison with tumour functional information derived from positron-emission tomography

To evaluate and compare diffusion-weighted imaging (DWI) parameters derived from a non-Gaussian fitting model and positron-emission tomography (PET) parameters derived from 18F-fluoromisonidazole-PET (FMISO-PET) in patients with oral squamous cell carcinoma (OSCC). Primary sites were evaluated prospectively in 18 patients. DWI was performed using six b-values (0-2,500). Diffusion-related parameters of kurtosis value (K), the kurtosis-corrected diffusion coefficient (DK), diffusion heterogeneity (α), distributed diffusion coefficient (DDC), the slow diffusion coefficient (Dslow), and the apparent diffusion coefficient (ADC) were calculated from four diffusion-fitting models. Maximal standardised uptake values (SUVmax), mean standardised uptake values (SUVmean), and the tumour-to-muscle ration (TMR) of the SUV value were calculated for FMISO-PET. Spearman's correlation coefficient was used to evaluate the correlation between each non-Gaussian diffusion model parameters and PET parameter. There was moderate correlation between FMISO-PET SUVmax and Dslow (ρ=-0.45, p=0.06). In addition, there was good correlation between TMRmax and five non-Gaussian diffusion model parameters (K: ρ=0.65, p=0.004, DK: ρ=-0.72, p=0.0008, DDC: ρ=-0.75, p=0.0003, ADC: ρ=-0.74, p=0.0005, and Dslow: ρ= -0.65, p=0.003), and between TMRmean and five non-Gaussian model parameters (K: ρ=0.64, p=0.005, DK: ρ=-0.61, p=0.007, DDC: ρ=-0.63, p=0.005, ADC: ρ=-0.61, p=0.007, and Dslow: ρ=-0.56, p=0.015). Non-Gaussian diffusion model parameters can be related to tumour hypoxia.

The role of 18FDG PET/CT imaging of aortic atherosclerosis: prospective study and technique optimization

BackgroundAtherosclerosis is an inflammatory disease of the inner wall of large and medium-sized arteries. The progress of atherosclerosis based on a lot of factors, including systemic involvement of disease, the precise vascular arterial affection, and the degree of flow obstruction. We aim in this study to estimate the FDG uptake of the aortic wall in the early and delayed imaging and to correlate this with the morphologic changes detected by CT.ResultsThis is a prospective study that was performed through 1 year. The study included 50 patients [30 males (60%) and 20 females (40%)] with male to female mean ratio 1.5:1 and their mean age 58.3 ± 15.7 years. Each patient underwent dual time-point 18F-FDG PET CT imaging at ~ 60 min (Early images) and 180 min (delayed images) after the administration of 18F-FDG. For each patient, the global 18F-FDG uptake in the aorta was determined by manually drawing regions of interest (ROIs) around the outer part of the arterial wall on every slice of the attenuation-corrected transverse PET CT images. Per-patient, per-time-point, per-vessel, and per-ROI radiotracer decay-corrected and body weight-corrected SUVs were calculated, resulting in a single mean value of maximum SUV for the aorta. The aortic wall FDG uptake was measured in both early and delayed images and expressed in terms of SUVmax. Then Retention index percentage of the aorta was measured. The retention index percentage was calculated by subtracting the SUVmax in early images from the SUVmax in delayed images and dividing by SUVmax in early images.ConclusionAortic wall FDG uptake can be used as an additional parameter as well as a biomarker on evaluation of the arterial atherosclerotic activity. Delayed post 3 h FDG imaging is more accurate than the routine early post 1 h imaging in evaluating the atherosclerotic activity.

Metrics to Evaluate PET Response to Therapy Based on 3D Analysis

The disadvantage of visualizing tomography by slices is that an important attribute of the object, its volume, is not easily perceived or measured. In oncology this creates a problem, which is addressed here: if early detection and response to treatment are an important prognostic element, then volume is important. The literature has proposed surrogates to volume derived from measures on slices, but geometrically they are not well founded. Actual volume analysis is not complex, and the proposed method applies equally well to organs as to tumors. Volume based measures are more sensitive than individual SUV values, of which the commonly most used is the maximum Standardized Uptake Value (SUVm). If the tumor volume is defined, it can be replaced by the total tumor SUV (SUVt). If the metric for change is the ratio after/(before + after), in the patient population analyzed here, the SUVm metric averages 0.132 for response and 0.662 for progression, the total SUVt range is 0.069 to 0.734. In contrast to SUVt, SUVm is based on a weak sampling method since it is based on the value of a single voxel of more than 10 million.

The multidisciplinary team plays an important role in the prediction of small solitary pulmonary nodules: a propensity-score-matching study.

According to guidelines, it is recommended that pulmonary nodules be discussed by a multidisciplinary team (MDT); however, the evidence for the effectiveness of MDT is sparse. To demonstrate the importance of the involvement of an MDT for the prediction of small solitary pulmonary nodules, we conducted this retrospective study. The patient database of those who attended our MDT and the electronic medical record system of our hospital was used; we collected all the data from patients found with small solitary pulmonary nodules (≤2 cm), which were suspected as malignant and who received a resection of the nodules. We summarized their characteristics and analyzed them, and then compared the post-operation pathological diagnosis of the patients who attended an MDT to those who did not participate in an MDT during the same period (2017-2019.2). We also collected the follow-up data. Propensity-score-matching was utilized during the process of analysis to get a more reliable conclusion. Most of the qualified patients were female. Most of the small solitary pulmonary nodules (≤2 cm) were adenocarcinoma and located on the right upper lobe. There were no differences in the SUV value between malignant nodules and benign nodules. After propensity-score matching, the total positive prediction value of small solitary pulmonary nodules (≤2 cm) without an MDT was 69.4%, while that with MDT was 77.6%; the difference was not significant with a P value of 0.30. The negative predictive value of MDT was 76.2%. In developing countries, small solitary pulmonary nodules tend to be more correctly diagnosed with MDT.

Quantitative implications of the updated EARL 2019 PET\u2013CT performance standards

PurposeRecently, updated EARL specifications (EARL2) have been developed and announced. This study aims at investigating the impact of the EARL2 specifications on the quantitative reads of clinical PET–CT studies and testing a method to enable the use of the EARL2 standards whilst still generating quantitative reads compliant with current EARL standards (EARL1).MethodsThirteen non-small cell lung cancer (NSCLC) and seventeen lymphoma PET–CT studies were used to derive four image datasets—the first dataset complying with EARL1 specifications and the second reconstructed using parameters as described in EARL2. For the third (EARL2F6) and fourth (EARL2F7) dataset in EARL2, respectively, 6 mm and 7 mm Gaussian post-filtering was applied. We compared the results of quantitative metrics (MATV, SUVmax, SUVpeak, SUVmean, TLG, and tumor-to-liver and tumor-to-blood pool ratios) obtained with these 4 datasets in 55 suspected malignant lesions using three commonly used segmentation/volume of interest (VOI) methods (MAX41, A50P, SUV4).ResultsWe found that with EARL2 MAX41 VOI method, MATV decreases by 22%, TLG remains unchanged and SUV values increase by 23–30% depending on the specific metric used. The EARL2F7 dataset produced quantitative metrics best aligning with EARL1, with no significant differences between most of the datasets (p>0.05). Different VOI methods performed similarly with regard to SUV metrics but differences in MATV as well as TLG were observed. No significant difference between NSCLC and lymphoma cancer types was observed.ConclusionsApplication of EARL2 standards can result in higher SUVs, reduced MATV and slightly changed TLG values relative to EARL1. Applying a Gaussian filter to PET images reconstructed using EARL2 parameters successfully yielded EARL1 compliant data.

Prognostic value of pretreatment (18)F-FDG PET-CT metabolic parameters in patients with advanced extranodal NK/T cell lymphoma

Objective: To investigate the prognostic values of the maximum standardized uptake value (SUV(max)), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) calculated from pretreatment (18)F-fluorodeoxy glucose ((18)F-FDG) PET-CT results of patients with advanced extranodal NK/T cell lymphoma (ENKTL). Methods: The clinic data, follow-up data and pretreatment (18)F-FDG PET-CT data of 45 patients with ENKTL of stage Ⅳ were collected. The optimal cutoff value of progression-free survival (PFS) of SUV(max), MTV and TLG were analyzed by using receiver-operating characteristic (ROC) curve. The Kaplan-Meier method, Log-rank test and COX proportional hazards model were used for survival analysis, univariate analysis and multivariate analysis, respectively. Results: The median SUV(max), MTV and TLG of 45 ENKTL patients were 17.98, 70.18 and 755.42, respectively. ROC curve showed that the area under the curve (AUC) of SUV(max), MTV and TLG were 0.504 (P=0.970), 0.868 (P<0.001) and 0.848 (P=0.001), respectively. The value of SUV(max) was too small to fit for calculating the cutoff value of AUC. The cutoff value of MTV was 42.54 (sensitivity =78.1% and specificity =84.6%), and the cutoff value of TLG was 435.15 (sensitivity=75.0% and specificity =76.9%). Univariate analysis showed that lactate dehydrogenase (LDH) level, epstein-barr virus (EBV)-DNA, Eastern Cooperative Oncology Group (ECOG) score, bone marrow, Korean prognostic index (KPI), MTV, TLG were significantly related with PFS (all P<0.05), and lactate dehydrogenase (LDH) level, EBV-DNA, ECOG score, primary tumor location, KPI, MTV, TLG were significantly related with overall survival (OS) (all P<0.05). Multivariate analysis showed that KPI, MTV and TLG were independent prognostic predictors of PFS and OS (all P<0.05). Conclusions: MTV and TLG of pretreatment (18)F-FDG PET-CT are independent prognostic factors for PFS and OS of patients with advanced ENKTL. MTV and TLG may be more fit for evaluating the prognosis of ENKTL patients than SUV(max).

Correlation of SUVmax and Apparent Diffusion Coefficient Values Detected by Ga-68 PSMA PET/MRI in Primary Prostate Lesions and Their Significance in Lymph Node Metastasis: Preliminary Results of an On-going Study

Objectives:Gallium-68 (Ga-68) prostate specific membrane antigen (PSMA) positron emission tomography (PET) has been shown to be more accurate than multiparametric prostate magnetic resonance imaging (MRI) in detection of primary prostate lesions. Using hybrid PET/MRI we aim to detect the correlation between SUVmax and apparent diffusion coefficient (ADC) in primary prostate lesions and to assess their prognostic value in detection of lymph node (LN) metastasis.Methods:Twenty-six patients, who were diagnosed as having prostate cancer with biopsy and underwent Ga-68 PSMA PET/MRI together with biparametric prostate MRI (bpMRI) were included. SUVmax, SUVmean and ADC were recorded for index lesions drawing a region of interest (ROI) of 1 cm2 around the pixel with the highest SUVmax (ROI-1) and another ROI following borders of prostate tumor detected by bpMRI (ROI-2). Presence of LN metastasis was recorded according to PSMA PET/MRI.Results:SUVmax was inversely correlated with ADC (ROI-1: p=0.010; ROI-2: p=0.017 for b=800). SUVmax and SUVmeans were both higher in patients with LN metastasis and ADC was lower in patients with LN metastasis for ROI-1. SUVmax cut-off value of 19.8 for ROI-1 and 20.9 for ROI-2 had sensitivity and specificity of 77.8% and 76.5%, respectively for detection of LN metastasis, whereas ADC (b=800) cut-off value of 0.92x10-3 mm2/s had sensitivity and specificity of 87.5% and 76.5%, respectively. SUVmax/ADC (b=800) ratio increased the sensitivity and specificity to 100% and 82.4%, respectively.Conclusion:SUV and ADC values are inversely correlated in primary prostate lesions and the combined use of both values increases the diagnostic accuracy of hybrid PET/MRI in the detection of primary prostate lesions.

Associations between FDG-PET and Ki 67-index in head and neck cancer: A meta-analysis.

Background:FDG-PET might be able to reflect histopathology features of tumors. Ki 67 in head and neck carcinomas (HNSCC). The present study sought to elucidate the association between Ki 67 index and SUVmax based upon a large patient sample.Methods:PubMed database was screened for studies analyzed the relationship between Ki 67 and SUV in HNSCC. Nine studies comprising 211 patients were suitable for analysis.Results:SUVmax increased with tumor grade and was statistically significant different between G1, G2, and G3 tumors. The ROC analysis for discrimination between G1/G2 and G3 tumors revealed an area under curve of 0.71. In the overall patient sample, SUVmax correlated statistically significant with Ki 67 index (r = 0.154, P = .032).Conclusion:The present study identified a weak correlation between SUV values and proliferation index Ki 67 index in HNSCC in a large patient sample. Therefore, SUVmax cannot be used as surrogate parameter for proliferation activity in HNSCC.

301P - A novel PET parameter for cancer stem cell metabolism: Early prediction of chemosensitivity to neoadjuvant chemotherapy in locally advanced breast cancer

BackgroundEarly predicting the pathologic complete response (pCR) after neoadjuvant chemotherapy in patients with locally advanced breast cancer (LABC) is closely associated with clinical outcomes. However, conventional metabolic parameters using baseline 18F-FDG PET/CT have failed to accurately predict the pCR. Breast cancer stem cells (CSCs) are known for their established role in chemoresistance. We designed a new PET parameter for CSC metabolism (MTVcsc) from pretreatment 18F-FDG PET/CT by using distinctive glucose metabolism between CSCs and differentiated cancer cells, and aimed to evaluate the prognostic value of the MTVcsc. MethodsA total of 71 patients with LABC who underwent initial 18F-FDG PET/CT before NAC were included in this study. The SUV values of single voxels within the primary tumor were clustered by performing k-means clustering using R version 3.5.3 and MTVcsc was derived by calculating the volume of the most glycolytic cluster. The predictive values of the MTVcsc, as well as clinicopathologic and conventional metabolic parameters (SUVmax, MTV, TLG) for pCR, were analyzed by multivariable logistic regression. ResultsSeventeen patients were excluded from the final analysis due to small tumor size (< 64 voxels). The lower MTVcsc and non-luminal subtypes were significantly associated with achieving pCR following NAC (Table). The MTVcsc outperformed the conventional PET parameters in predicting pCR. Table Univariable and multivariable logistic regression model of clinicopathologic and metabolic parameters for predicting pathologic complete response.Table: 301PTable: 301PParametersUnivariable analysisMultivariable analysisOR95% CIP valueOR95% CIP valueKi-67Low, < 20% High, ≥ 20%1.005.571.06-29.270.043Molecular subtypeLuminal A and B HER2 positive Triple negative1.001.0011.462.07-63.360.00513.71.75-107.360.0136.551.05-40.670.04417.421.41-215.040.026Metabolic parametersSUVmax Metabolic tumor volume (MTV) Total lesion glycolysis (TLG) MTVcsc0.980.83-1.160.8140.980.94-1.020.2810.990.98-1.000.2310.290.10-0.890.0310.210.05-0.820.025 ConclusionsMTVcsc, a novel PET parameter for CSC metabolism, provides predictive value for pCR. By further stratifying LABC patients with a combination of MTVcsc and molecular subtype at initial staging workup, achieving pCR after NAC can be early predicted more accurately. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Evaluating Utility of 4D PET-CT Motion Freeze Imaging for Lung SABR

In Lung stereotactic ablative radiotherapy (SABR), 4D PET-CT gives an edge over static 3D PET-CT in target volume delineation given its ability to reduce motion artifacts. Motion Freeze (MF) PET imaging combines the quantitative benefits of 100% counts of 4D phase-matched PET-CT imaging into a single static image by collecting CT & PET data at each phase of the breathing cycle, then matching the data for attenuation consistency. This provides further robustness of biologic target volume delineation with reduced image noise. The authors evaluated the utility of 4D PET-CT MF imaging in lung SABR treatments & the consequent dosimetric impact when either motion inclusive (retrospective imaging) technique or gating technique were to be used. Five patients of lung SABR were included for purpose of this dosimetric study (1 Ca lung and 4 lung oligo-metastasis). All patients underwent 4D CT /PET scan with the RPM system on 16 slice PET-CT scanner. The 4D CT and 4D PET data were binned in 10 phases of respiratory cycle. The Motion match software was utilized to create a MF image of all the 10 PET bins (MF-10) and 3 bins corresponding to end expiratory phase 40%,50%,60% (MF-3) in which tumor position was relatively stable. For study purpose we analyzed 3 clinical scenarios for target delineation (a) target volume generated using 4D CT alone (b) 4D CT all bins deformably registered with MF-10 (c) 4D-CT 3 bins deformably registered with corresponding MF-3, using gradient based intensity based registration algorithm. Three VMAT 6 MV FFF plans were generated for all the above all 3 volumes. The dosimetric parameters analysed included Target volume coverage, dose spillage (high, intermediate and low dose) & OAR doses as per RTOG protocol. Statistical comparison was done using paired sample t test in statistical analysis software. The target volume was reduced using 4D PET MF 10 & MF 3 as compared to 4D CT alone though the values were statistically insignificant [P=0.75(MF10), P=0.68 (MF3)]. There was statistically insignificant difference in target volume coverage parameters i.e. Conformity index, Heterogeneity index, dose spillage (high, intermediate and low dose) among all the plans. However the trend towards reduced OAR doses was seen in MF 10 plan & MF 3 plan as compared to 4D CT plan {Lungs V20 [P=0.06(MF10), P=0.08(MF3)], Heart Dmax [P=0.02(MF10), P=0.03(MF3)], Spinal cord Dmax [P=0.08(MF10), P=0.07(MF3)], Chest wall Dmax [P=0.001(MF10), P=0.037(MF3)], Great Vessel Dmax [P=0.03(MF10), P=0.045 (MF3)]}. Inclusion of 4D PET-CT MF scan 10 bins (non gated delivery) or 3 bins (gated delivery) can improvise the robustness of Lung SABR in terms of better target volume delineation, OAR doses & estimation of SUV values helping in better treatment response evaluation in follow up. While this study, first of its kind for Lung SABR, gives proof-of-concept & integration into workflow, a larger sample size evaluating 4D PET-CT MF would address the target delineation issue.

18F-FDG-PET/CT in Canine Mammary Gland Tumors.

Medical imaging techniques play a central role in clinical oncology, helping to obtain important information about the extent of disease, and plan treatment. Advanced imaging modalities such as Positron Emission Tomography–Computed Tomography (PET/CT), may help in the whole-body staging in a single procedure, although the lesions should be carefully interpreted. PET/CT is becoming commonly used in canine cancer patients, but there is still limited information available on specific tumors such as mammary cancer. We evaluated the utility of fluorine-18 fluorodeoxyglucose (18F-FDG)-PET/CT to detect malignant lesions in eight female dogs with naturally occurring mammary tumors. A whole-body scan was performed prior to surgery, and mammary and non-mammary lesions detected either on PET/CT or during pre-surgical physical exam were resected when possible and submitted for histopathological examination. Multiple mammary lesions involving different mammary glands were detected in 5/8 dogs, for a total of 23 lesions; there were 11 non-mammary-located lesions in 6/8 dogs, three of these were lung or lymph node metastasis. A total of 34 lesions were analyzed: 22 malignant (19 mammary tumors and three metastatic lesions), and 12 benign (four mammary lesions and eight of non-mammary tissues). Glucose uptake by maximum standardized uptake value (SUVmax) was analyzed and correlated with tumor size, and benign vs. malignant pathology. We found that the minimum tumor size needed to distinguish malignant lesions according to the SUVmax was 1.5 cm; benign and malignant lesions <1.5 cm did not differ in glucose uptake (mean SUVmax = 1.1). In addition, a SUVmax value >2 was 100% sensitive for malignancy. Combining these data, lesions >1.5 cm with a SUVmax >2 had a positive predictive value of 100%. Finally, we did not find an association between SUVmax and histologic subtype or grade, which may be present in a larger sample. Thus, 18F-FDG PET/CT is useful for distinguishing malignant from benign lesion but further imaging of dogs with diverse tumors, should establish characteristic SUV value cutoffs for detecting primary and metastatic disease, and distinguishing them from benign lesions.

MLTI-18. PRECISION IMAGING OF METASTATIC AND PRIMARY BRAIN TUMORS AFTER RADIATION WITH 18F-FDOPA PET-MRI IS FEASIBLE AND COST EFFECT

PURPOSE: Post-radiation changes in the brain can mimic tumor recurrence on MRI, requiring multiple short term follow-ups to differentiate tumor progression from radiation necrosis. We propose combining functional and anatomic imaging with FDOPA PET tracer in hybrid PET-MRI to improve detection of tumor recurrence. MATERIALS AND METHODS: Seventeen adult patients treated with radiation therapy were identified - four with metastatic disease from breast and lung cancer and thirteen with primary brain glioma (11 IDH wildtype glioblastoma and 2 astrocytoma). Patients were scanned on hybrid PET-MRI (GE Healthcare) with clinical MRI brain sequences and dynamic FDOPA uptake. Dynamic FDOPA uptake within these tumors over 45 minutes after tracer injection was analyzed and compared to ADC histogram analysis. RESULTS: For each of the patients, clinical multi sequence gadolinium enhanced MRI and dynamic PET imaging for up to 45 minutes with 18F-FDOPA amino acid tracer was obtained. The total cost savings of scanning 17 patients in groups was 51.4% ($28,321), as opposed to the cost of individual radiosynthesis performed for each study. Quantitative analysis of tracer uptake in striatum, internal carotid artery, and superior sagittal sinus were performed with appropriate accumulation and subsequent washout of tracer respectively. Successful dynamic FDOPA uptake within the tumor was seen in all patients and ratio of tumor to contralateral ROI were found to range from 1.8–4.5. While raw SUV values did not differentiate between recurrent tumor and radiation changes, T/C SUVmax ratios were elevated to 4.5 in recurrent glioblastoma, 2.5 in hypoxic treated glioblastoma, and 1.8 in non-recurrent metastatic breast cancer after gamma knife treatment. CONCLUSION: Batch imaging of patients with [18F]FDOPA PET-MRI is feasible and cost effective. Understanding radionuclide synthesis process is critical for increasing accessibility of novel PET tracers to patients and results in significant cost savings.

Biodistribution and radiation dosimetry of [18F]-JK-PSMA-7 as a novel prostate-specific membrane antigen-specific ligand for PET/CT imaging of prostate cancer

AimWe investigated the whole-body distribution and the radiation dosimetry of [18F]-JK-PSMA-7, a novel 18F-labeled PSMA-ligand for PET/CT imaging of prostate cancer.MethodsTen patients with prostate cancer and biochemical recurrence or radiologic evidence of metastatic diseases were examined with 329–384 MBq (mean 359 ± 17 MBq) [18F]-JK-PSMA-7. Eight sequential positron emission tomography (PET) scans were acquired from 20 min to 3 h after injection with IRB approval. The kidneys, liver, lungs, spleen, and salivary glands were segmented into volumes of interest using the QDOSE dosimetry software suite (ABX-CRO, Germany). Absorbed and effective dose were calculated using the ICRP-endorsed IDAC 1.0 package. The absorbed dose of the salivary glands was determined using the spherical model of OLINDA 1.1. PSMA-positive lesions were evaluated separately. Quantitative assessment of the uptake in suspicious lesions was performed by analysis of maximum (max) and peak SUV values. The gluteus maximus muscle (SUVmean) served as a reference region for the calculation of tumor-to-background ratios (TBR’s).ResultsPhysiologic radiotracer accumulation was observed in the salivary and lacrimal glands, liver, spleen, and intestines, in a pattern resembling the distribution known from other PSMA-tracers with excretion via urinary and biliary pathways. The effective dose from [18F]-JK-PSMA-7 for the whole body was calculated to be 1.09E−02 mGy/MBq. The highest radiation dose was observed in the kidneys (1.76E−01 mGy/MBq), followed by liver (7.61E−02 mGy/MBq), salivary glands (4.68E−02 mGy/MBq), spleen (1.89E−02 mGy/MBq), and lungs (1.10E-2 mGy/MBq). No adverse effects of tracer injection were observed. Six out of ten patients were scored as PSMA-positive. A total of 18 suspicious lesions were analyzed, which included six bone lesions, nine lymph nodes, and three local lesions within the prostate fossa. The values for the SUVmax and SUVpeak in the PSMA-positive lesions increased until 60 min p.i. and remained at this intensity in the PET/CT scans until 140 min. In the period between 170 and 200 min after injection, a further significant increase in SUVmax and SUVpeak within the PSMA-positive lesions was observed.ConclusionsThe highest TBR of [18F]-JK-PSMA-7 was found 3 h after injection. From the kinetically collected data, it can be concluded that this trend may also continue in the further course. The start of the PET/CT acquisition should be chosen as late as possible. The high uptake in suspicious lesions in terms of absolute SUVmax and relative TBR values indicates potentially high sensitivity of the tracer for detection of prostate cancer manifestations.