Whole-body FDG-PET Research Articles

Development of Combination Methods for Detecting Malignant Uptakes Based on Physiological Uptake Detection Using Object Detection With PET-CT MIP Images.

Deep learning technology is now used for medical imaging. YOLOv2 is an object detection model using deep learning. Here, we applied YOLOv2 to FDG-PET images to detect the physiological uptake on the images. We also investigated the detection precision of abnormal uptake by a combined technique with YOLOv2. Using 3,500 maximum intensity projection (MIP) images of 500 cases of whole-body FDG-PET examinations, we manually drew rectangular regions of interest with the size of each physiological uptake to create a dataset. Using YOLOv2, we performed image training as transfer learning by initial weight. We evaluated YOLOv2's physiological uptake detection by determining the intersection over union (IoU), average precision (AP), mean average precision (mAP), and frames per second (FPS). We also developed a combination method for detecting abnormal uptake by subtracting the YOLOv2-detected physiological uptake. We calculated the coverage rate, false-positive rate, and false-negative rate by comparing the combination method-generated color map with the abnormal findings identified by experienced radiologists. The APs for physiological uptakes were: brain, 0.993; liver, 0.913; and bladder, 0.879. The mAP was 0.831 for all classes with the IoU threshold value 0.5. Each subset's average FPS was 31.60 ± 4.66. The combination method's coverage rate, false-positive rate, and false-negative rate for detecting abnormal uptake were 0.9205 ± 0.0312, 0.3704 ± 0.0213, and 0.1000 ± 0.0774, respectively. The physiological uptake of FDG-PET on MIP images was quickly and precisely detected using YOLOv2. The combination method, which can be utilized the characteristics of the detector by YOLOv2, detected the radiologist-identified abnormalities with a high coverage rate. The detectability and fast response would thus be useful as a diagnostic tool.

Features and clinical impact of extra-cardiac lesions with 18F-fluorodeoxyglucose positron emission tomography in patients with suspected cardiac sarcoidosis.

BackgroundSarcoidosis is a systemic inflammatory disorder and can often affect any other organs beyond the heart. Whole-body 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is used to detect not only cardiac but also extra-cardiac involvement of sarcoidosis. However, the features and clinical impact of extra-cardiac lesions have not yet been fully elucidated. Therefore, this study aimed to clarify these using FDG-PET.Methods and resultsWe enrolled 120 consecutive patients with abnormal findings clinically suggesting cardiac sarcoidosis who underwent whole-body FDG-PET. In this study, a patient with suspected cardiac sarcoidosis was defined as one having both clinically suspected findings and FDG-PET positive cardiac uptake. Subsequently, a total of 36 patients with suspected cardiac sarcoidosis were found and analyzed. Extra-cardiac involvement was detected in 35 lesions of 14 patients (39% per patient). In particular, the extra-cardiac lesions were widely distributed throughout the body, and mediastinal/hilar lymph node involvement was most commonly observed. In most of the patients (93% per patient, 13/14), the extra-cardiac lesions were localized in the regions that were considered more accessible with less risk of complication compared with endomyocardial biopsy (EMB). Based on the FDG-PET findings, 8 patients underwent extra-cardiac biopsy without complication, and its diagnostic sensitivity for histological sarcoidosis was high (75%, 6/8). Moreover, FDG-PET-guided extra-cardiac biopsy could confirm histological sarcoidosis in 4 lesions that EMB failed to prove.ConclusionsExtra-cardiac involvement in patients with suspected cardiac sarcoidosis was relatively high. FDG-PET-guided extra-cardiac biopsy may be safe and useful for the imaging based diagnosis of cardiac sarcoidosis.

FIGO 2018 staging criteria for cervical cancer: Impact on stage migration and survival

ObjectiveTo compare FIGO 2009 and FIGO 2018 cervical cancer staging criteria with a focus on stage migration and treatment outcomes. MethodsThis study is based on a database cohort of 1282 patients newly diagnosed with cervical cancer from 1997 to 2019. All underwent standard clinical examination and whole-body FDG-PET. Tumor stage was recorded using the FIGO 2009 system, which excluded surgical pathologic, FDG-PET and other advanced imaging findings, and then re-classified to the FIGO 2018 system, including surgical pathologic and imaging findings. Patient management was based on clinical, surgical, and imaging findings. Stage migration and prognosis were evaluated. ResultsThe distribution per the 2009 staging system was stage I in 593 (46%), stage II in 342 (27%), stage III in 263 (21%), and stage IV in 84 (7%) and the 2018 staging system was stage I in 354 (28%), stage II in 156 (12%), stage III in 601 (47%), and stage IV in 171 (13%). No patients were down-staged. Stage migration occurred in 53% (676/1282) and was attributable to detection of occult lymph node metastasis in 520 (41%), occult distant metastasis in 90 (7%), and tumor size and extent in 66 (5%). The 5-year progression-free survivals (PFS) by FIGO 2009 versus FIGO 2018 were as follows: stage I, 80% vs. 87% (p = 0.02); stage II, 59% vs. 71% (p = 0.002); stage III, 35% vs. 55% (p < 0.001), and stage IV, 20% vs. 16% (p = 0.41). ConclusionInclusion of surgical pathologic and imaging findings resulted in upward stage migration in the majority, mostly related to nodal and distant metastasis. While FIGO 2018 improves survival discriminatory ability for stages I and IV patients, survival remains heterogeneous among stage III substages.

A convolutional neural network-based system to classify patients using FDG PET/CT examinations

BackgroundAs the number of PET/CT scanners increases and FDG PET/CT becomes a common imaging modality for oncology, the demands for automated detection systems on artificial intelligence (AI) to prevent human oversight and misdiagnosis are rapidly growing. We aimed to develop a convolutional neural network (CNN)-based system that can classify whole-body FDG PET as 1) benign, 2) malignant or 3) equivocal.MethodsThis retrospective study investigated 3485 sequential patients with malignant or suspected malignant disease, who underwent whole-body FDG PET/CT at our institute. All the cases were classified into the 3 categories by a nuclear medicine physician. A residual network (ResNet)-based CNN architecture was built for classifying patients into the 3 categories. In addition, we performed a region-based analysis of CNN (head-and-neck, chest, abdomen, and pelvic region).ResultsThere were 1280 (37%), 1450 (42%), and 755 (22%) patients classified as benign, malignant and equivocal, respectively. In the patient-based analysis, CNN predicted benign, malignant and equivocal images with 99.4, 99.4, and 87.5% accuracy, respectively. In region-based analysis, the prediction was correct with the probability of 97.3% (head-and-neck), 96.6% (chest), 92.8% (abdomen) and 99.6% (pelvic region), respectively.ConclusionThe CNN-based system reliably classified FDG PET images into 3 categories, indicating that it could be helpful for physicians as a double-checking system to prevent oversight and misdiagnosis.

SUV variability in EARL-accredited conventional and digital PET

BackgroundA high SUV-reproducibility is crucial when different PET scanners are in use. We evaluated the SUV variability in whole-body FDG-PET scans of patients with suspected or proven cancer using an EARL-accredited conventional and digital PET scanner.In a head-to-head comparison we studied images of 50 patients acquired on a conventional scanner (cPET, Ingenuity TF PET/CT, Philips) and compared them with images acquired on a digital scanner (dPET, Vereos PET/CT, Philips). The PET scanning order was randomised and EARL-compatible reconstructions were applied.We measured SUVmean, SUVpeak, SUVmax and lesion diameter in up to 5 FDG-positive lesions per patient. The relative difference ΔSUV between cPET and dPET was calculated for each SUV-parameter. Furthermore, we calculated repeatability coefficients, reflecting the 95% confidence interval of ΔSUV.ResultsWe included 128 lesions with an average size of 19 ± 14 mm. Average ΔSUVs were 6-8% with dPET values being higher for all three SUV-parameters (p < 0.001). ΔSUVmax was significantly higher than ΔSUVmean (8% vs. 6%, p = 0.002) and than ΔSUVpeak (8% vs. 7%, p = 0.03). Repeatability coefficients across individual lesions were 27% (ΔSUVmean and ΔSUVpeak) and 33% (ΔSUVmax) (p < 0.001).ConclusionsWith EARL-accredited conventional and digital PET, we found a limited SUV variability with average differences up to 8%. Furthermore, only a limited number of lesions showed a SUV difference of more than 30%. These findings indicate that EARL standardisation works.Trial registrationThis prospective study was registered on the 31th of October 2017 at ClinicalTrials.cov. URL: https://clinicaltrials.gov/ct2/show/NCT03457506?id=03457506&rank=1.

Head and Neck Cancer in Belgium: Quality of Diagnostic Management and Variability Across Belgian Hospitals Between 2009 and 2014.

Aims: The study assessed the quality of diagnosis and staging offered to patients with a head and neck squamous cell carcinoma (HNSCC) and the variability across Belgian hospitals.Methods: In total, 9,245 patients diagnosed with HNSCC between 2009 and 2014, were identified in the population-based Belgian Cancer Registry (BCR). The BCR data were coupled with other databases providing information on diagnostic and therapeutic procedures reimbursed by the compulsory health insurance, vital status data, and comorbidities. The use of diagnosis and staging procedures was assessed by four quality indicators (QI) (i.e., use of dedicated head and neck imaging studies, use of PET-CT, TNM reporting and interval between diagnosis and start of treatment), for which a target was defined before the analysis. The association between the binary QIs and observed survival was assessed using Cox proportional hazard models adjusted for potential confounders.Results: Overall, 82.5% of patients received staging by MRI and/or CT of the head and neck region before the start of treatment. In 47.6% of stage III–IV patients eligible for treatment with curative intent, a whole-body FDG-PET(/CT) was performed. The proportion of patients whose cTNM and pTNM stage was reported to the BCR was 80.5 and 78.4%, respectively. The median interval from diagnosis to first treatment with curative intent was 32 days (IQR: 19–46). For none of these QIs the pre-set targets were reached and a substantial variability between centers was observed for all quality indicators. No binary QI was significantly associated with observed survival.Conclusions: The four quality indicators related to diagnosis and staging in HNSCC all showed substantial room for improvement. For none of them the pre-set targets were met at the national level and the variability between centers was substantial. Each Belgian hospital received an individual feedback report in order to stimulate reflection and quality improvement processes.

Detection of distant metastatic disease by positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) at initial staging of cervical carcinoma.

The detection of distant metastatic disease in cervical cancer patients at diagnosis is critical in accurate prognostication and directing treatment strategies. This study describes the frequency and sites of distant metastatic disease at diagnosis in patients with cervical cancer as detected by positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET). Patients with newly diagnosed cervical cancer underwent pre-treatment whole-body FDG-PET starting in 1997 at an academic institution. Patients with evidence of distant FDG-avid disease, defined as disease outside of typical sites of lymphatic spread, were included for analyses. Patients were not surgically staged, but biopsy to confirm metastatic disease was attempted at the discretion of the treating physicians. Overall survival was calculated using Kaplan-Meier analysis. From 1997 to 2017, 72 (6.2%) of 1158 consecutively evaluated cervical cancer patients exhibited FDG-avid distant disease at diagnosis; 27 (38%) of these had biopsy confirmation of distant disease. Only 35 (49%) of FDG-detected metastases were clinically apparent. The sites of distant disease were lung (35%), multiple sites (25%), omentum (16.5%), bone (16.5%), and liver (7%). There were 12 (17%) patients with distant disease who did not display FDG-avid lymph nodes. Median overall survival among patients with distant FDG-avid disease was 7.0 months (95% CI 4.3 to 9.7). Patients with multiple sites of distant disease demonstrated the worst overall survival. Distant metastatic disease detected by FDG-PET is found in 6.2% of patients with cervical cancer at the time of initial diagnosis and the most common site of disease is the lung. Further prospective investigation is warranted to delineate best treatment practices for cervical cancer patients presenting with distant metastases.

The Prognostic Role of Maximum Standardized Uptake Value of 18 F-FlouroDeoxy Glucose Positron Emission Tomography-Computed Tomography in Head and Neck Cancer Patients Undergoing Chemoradiotherapy.

Aims and Objectives:This retrospective study aims at correlating the pre- and post-therapy maximal standardized uptake values (SUVmax) of the whole-body 18-flourodeoxy glucose positron emission tomography (FDG-PET) scan with tumor response in patients with head and neck squamous cell cancer undergoing chemoradiotherapy.Materials and Methods:Data for this retrospective study were taken from the clinical records of 20 evaluable head and neck cancer patients who had availed treatment and evaluation at our institute during the previous year (March 2017–April 2018). All these above-mentioned patients had undergone chemoradiation at our center for locally advanced squamous cell carcinoma of the head and neck and had undergone pre- and post-therapy whole-body FDG PET scan. The posttherapy PET-computed tomography (CT) was advised after 8 weeks’ postcompletion of therapy. During the PET CT scan, images were acquired 1 h after injection of FDG. Pre- and post-therapy SUVmax were recorded and correlated with immediate treatment response.Results:The mean pretherapy SUVMax of the primary tumor was 10.27 ranging from 4.5 to 26.17. The mean pretherapy SUVMax of the node was 5.34 ranging from 0 to 17.9. The mean time of recording the posttherapy SUVMax was 3 months (range 2–5 months). The mean posttherapy SUVMax of the primary tumor was 1.05 ranging from complete metabolic response to 6.4. The mean posttherapy SUVMax of the node was 0.7 ranging from complete metabolic response to 5.43. The statistical analysis based on Wilcoxon–Signed Rank test revealed a statistically significant difference in the pre- and post-therapy SUVmax values for both primary tumor (P < 0.001) and regional node (P = 0.001). Majority of patients (n = 15) showed clinical remission; however, five patients had progressive disease at the time of evaluation.Conclusion:Although the retrospective study revealed that complete responders had a statistically significant reduction in the posttherapy SUVmax in comparison to the pretherapy SUVmax it failed to identify a cutoff value for pretherapy SUVmax which could predict the probable outcome of therapy. In view of the same further prospective studies need to be conducted with larger patient numbers including various other tumor metabolic markers for greater clarity.

P3.08-04 OMEGA, A Randomized Trial of Local Ablative Therapy Vs. Conventional Treatment in Oligometastatic NSCLC – Trial in Progress

A recent randomized phase 2 study has shown that local ablative therapy in addition to systemic treatment was superior to maintenance therapy in prolonging disease-free survival in NSCLC patients harboring up to three metastatic sites. Oligometastatic lung cancer (OM-NSCLC) seems thus to be associated with a better prognosis than usual Stage IV non-small cell lung cancer when radical local therapy of all metastatic sites is administered but the impact of such an approach on overall survival and quality of life remains unclear A consortium of tertiary referral centres involved in Lung Cancer management at the national level was established with the aim of setting up a randomized trial addressing this issue A randomized trial of local ablative therapy in OM-NSCLC patients with potentially resectable or locally controlled primary tumors has been designed and 7 tertiary referral centers agreed to participate Patients with synchronous or metachronous oligometastatic lung cancer (1-3 metastatic lesions) will be randomized to local ablative therapy + standard treatment Vs. standard treatment. Balancing between study arms will be performed according to synchronous vs. metachronous presentation, Number of oligometastases, Nodal status and Oncogene-addiction or PDL-1 expression. Primary outcome will be Overall Survival (OS) from randomization. The sample size is set to 195 patients. Inclusion criteria include adequate performance status, primary tumor controlled or controllable staging with whole-body FDG PET scan and brain MRI, fit to receive at least 3 cycles of platinum-based doublet chemotherapy, or immunotherapy or targeted agents according to molecular profile. Exclusion criteria include cerebral oligometastasis alone (will receive local therapy in any case), metastasis in sites where normal radiotherapy constraints cannot be met, multiple subsolid nodules in the absence of extrapulmonary metastasis, prior malignant tumor with some exceptions, relevant co-morbidities that would significantly reduce life expectancy on their own, Disease state and life status assessed on a 2-monthly basis by physical examination, whole-body CT scan plus repeat PET-scan if needed and Brain MRI if brain metastasis at enrolment. Toxicity and adverse events will be assessed according to NCI-Common Terminology Criteria. Quality of life will be assessed at randomization and after six months by the SF36/LCSS. There is a clear need for randomized controlled trials with overall survival as their main endpoint to confirm whether local ablative therapy indeed has a role in the management of oligometastatic lung cancer. The Omega trial will try to respond to such a need.

Monitoring scanner calibration using the image-derived arterial blood SUV in whole-body FDG-PET

BackgroundThe current de facto standard for quantification of tumor metabolism in oncological whole-body PET is the standardized uptake value (SUV) approach. SUV determination requires accurate scanner calibration. Residual inaccuracies of the calibration lead to biased SUV values. Especially, this can adversely affect multicenter trials where it is difficult to ensure reliable cross-calibration across participating sites. The goal of the present work was the evaluation of a new method for monitoring scanner calibration utilizing the image-derived arterial blood SUV (BSUV) averaged over a sufficiently large number of whole-body FDG-PET investigations.Data of 681 patients from three sites which underwent routine 18F-FDG PET/CT or PET/MR were retrospectively analyzed. BSUV was determined in the descending aorta using a three-dimensional ROI concentric to the aorta’s centerline. The ROI was delineated in the CT or MRI images and transferred to the PET images. A minimum ROI volume of 5 mL and a concentric safety margin to the aortic wall was observed. Mean BSUV, standard deviation (SD), and standard error of the mean (SE) were computed for three groups of patients at each site, investigated 2 years apart, respectively, with group sizes between 53 and 100 patients. Differences of mean BSUV between the individual groups and sites were determined.ResultsSD (SE) of BSUV in the different groups ranged from 14.3 to 20.7% (1.7 to 2.8%). Differences of mean BSUV between intra-site groups were small (1.1–6.3%). Only one out of nine of these differences reached statistical significance. Inter-site differences were distinctly larger (12.6–25.1%) and highly significant (P<0.001).ConclusionsImage-based determination of the group-averaged blood SUV in modestly large groups of whole-body FDG-PET investigations is a viable approach for ensuring consistent scanner calibration over time and across different sites. We propose this approach as a quality control and cross-calibration tool augmenting established phantom-based procedures.

PET/CT incidental detection of second tumor in patients investigated for pancreatic neoplasms

BackgroundPositron Emission Tomography/computed tomography (PET/CT) is an imaging technique which has a role in the detection and staging malignancies (both in first diagnosis and follow-up). The finding of an unexpected region of FDG (Fluorodeoxyglucose) uptake can occur when performing whole-body FDG-PET, raising the possibility of a second primary tumor. The aim of this study was to evaluate our experience of second primary cancer incidentally discovered during PET/CT examination performed for pancreatic diseases, during the initial work-up or follow-up after surgical resection.MethodsIn this study, a retrospective evaluation of a prospectively collected data base was performed. Three hundred ninety- nine patients with pancreatic pathology were evaluated by whole body PET/CT imaging from January 2004 to December 2014. Among them, 348 patients were scanned before surgical resection and 51 during the course of their follow-up (pancreatic cancer). Median follow-up time was 29 months (range 14-124).ResultsFifty-six patients (14%) had incidental uptake of FDG in their organs: 31 patients had focal uptake and 25 showed diffuse with or without focal uptake. All patients with focal uptake were investigated, and invasive malignancy was diagnosed in 22 patients: 14 colon, 4 lung, 1 larynx, 1 urothelial, 1 breast cancer, and 1 colon metastasis from pancreatic cancer. Twenty patients underwent resection, and 6 endoscopic removal of colonic polyps. Three patients were not operated for advanced disease, and two patients did not show any pathology (PET/CT false positive). Of the 10 patients investigated for diffuse uptake, no malignancy was found; none of these patients developed a second cancer during the follow-up.ConclusionsAs in other malignancies, unexpected FDG uptake can occur in patients having PET/CT investigation for pancreatic diseases. Focal uptake is likely to be a malignancy and deserves further investigations, although the stage and the poor prognosis of primary pancreatic cancer should be kept in mind. Some selected patients may benefit from the aggressive treatment of incidental lesions and show survival benefit.

Staging in childhood lymphoma: differences between FDG-PET and CT.

The clinical value of positron emission tomography using fluorine-18 fluoro-deoxy-glucose (FDG-PET) in the staging of adult lymphoma has been shown in many studies. However, there are only few data regarding childhood lymphoma. The purpose of this retrospective study was to compare the staging of childhood lymphoma using FDG-PET and the established computed tomography (CT). Whole-body FDG-PET was performed in 25 children with histologically proven Hodgkin's disease (n = 18) and non-Hodgkin's lymphoma (n = 7) using a dedicated PET. The findings were compared with the CT results. Both examinations, FDG-PET and CT, were assessed by two experienced physicians. In each patient, 30 regions were analysed (22 nodal, 8 extranodal). Each region was assessed using a five value scale (definitely/probably positive, equivocal, probably/definitely negative). 662 regions (470 nodal, 192 extranodal) were compared. 91 regions (81 nodal, 10 extranodal; 14%) were concordant positive and 517 regions (347 nodal, 170 extranodal; 78%) were concordant negative. In 47 regions, 48 discordant findings (7%) were described: 27 findings (22 nodal, 5 extranodal) were positive using FDG-PET and negative using CT whereas 21 findings (17 nodal, 4 extranodal) were positive using CT and negative using PET. A total of 7 regions (1%) were judged equivocal in one imaging modality (1 FDG-PET, 6 CT). Using FDG-PET as compared to CT, resulted in a higher staging in 4 of 25 patients and in a lower staging in 2 of 25 patients. Staging of childhood lymphoma using FDGPET shows differences compared with CT resulting in a different staging in 6 of 25 patients. Prospective studies are required to evaluate the impact of these discrepancies on the clinical management of pediatric patients.

Adult leukoencephalopathies with prominent infratentorial involvement can be caused by Erdheim-Chester disease.

Leukoencephalopathies with prominent involvement of cerebellum and brainstem, henceforward called prominent infratentorial leukoencephalopathies (PILs), encompass a variety of inherited and acquired white matter diseases. Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis likely under-diagnosed as cause of adult PIL. We reviewed the clinical and laboratory information of ten consecutive sporadic adult patients with PIL of unknown origin, who were investigated for ECD. There were seven males and three females; mean age at clinical onset was 49.6years (range 38-59); cerebellar ataxia with or without other neurological symptoms was the only or the main clinical manifestation; diabetes insipidus was present in three individuals. Eight patients had white matter focal supratentorial abnormalities, in addition to the infratentorial white matter changes. Six out of eight patients had spinal cord lesions. Thoraco-abdominal CT showed periaortic sheathing in two patients, whole-body FDG-PET revealed increased glucose uptake in the long bones of the legs in five patients, brain FDG-PET showed overt infratentorial hypermetabolism in one patient. In eight patients, ECD was confirmed by bone scintigraphy, pathological data, or both. Two ECD patients treated with vemurafenib showed a marked improvement of neurological symptoms and brain MRI abnormalities at 1 year follow-up. Symptoms of PIL can be the only clinical manifestation of ECD. Adult patients with PIL of unknown origin should undergo investigations aimed at unveiling ECD, including bone scintigraphy and whole-body FDG-PET. The early diagnosis allows starting disease-modifying therapies of an otherwise life-threatening disease.

Predictive value of initial FDG-PET features for treatment response and survival in esophageal cancer patients treated with chemo-radiation therapy using a random forest classifier.

PurposeIn oncology, texture features extracted from positron emission tomography with 18-fluorodeoxyglucose images (FDG-PET) are of increasing interest for predictive and prognostic studies, leading to several tens of features per tumor. To select the best features, the use of a random forest (RF) classifier was investigated.MethodsSixty-five patients with an esophageal cancer treated with a combined chemo-radiation therapy were retrospectively included. All patients underwent a pretreatment whole-body FDG-PET. The patients were followed for 3 years after the end of the treatment. The response assessment was performed 1 month after the end of the therapy. Patients were classified as complete responders and non-complete responders. Sixty-one features were extracted from medical records and PET images. First, Spearman’s analysis was performed to eliminate correlated features. Then, the best predictive and prognostic subsets of features were selected using a RF algorithm. These results were compared to those obtained by a Mann-Whitney U test (predictive study) and a univariate Kaplan-Meier analysis (prognostic study).ResultsAmong the 61 initial features, 28 were not correlated. From these 28 features, the best subset of complementary features found using the RF classifier to predict response was composed of 2 features: metabolic tumor volume (MTV) and homogeneity from the co-occurrence matrix. The corresponding predictive value (AUC = 0.836 ± 0.105, Se = 82 ± 9%, Sp = 91 ± 12%) was higher than the best predictive results found using the Mann-Whitney test: busyness from the gray level difference matrix (P < 0.0001, AUC = 0.810, Se = 66%, Sp = 88%). The best prognostic subset found using RF was composed of 3 features: MTV and 2 clinical features (WHO status and nutritional risk index) (AUC = 0.822 ± 0.059, Se = 79 ± 9%, Sp = 95 ± 6%), while no feature was significantly prognostic according to the Kaplan-Meier analysis.ConclusionsThe RF classifier can improve predictive and prognostic values compared to the Mann-Whitney U test and the univariate Kaplan-Meier survival analysis when applied to several tens of features in a limited patient database.

Application of whole-body FDG-PET for cancer screening in a cohort of hospital employees.

Whole-body positron emission tomography/computed tomography with the glucose analog 2-[18F]fluoro-2-deoxy-d-glucose (FDG-PET/CT) has been extensively used to screen for underlying malignancies in asymptomatic individuals. We were able to survey a cohort of hospital employees using FDG-PET/CT and to report the results herein.A total of 116 hospital employees older than 55 years old were offered whole-body FDG-PET in our hospital. Ninety-seven employees (83.6%) completed the assessment from February 2014 to August 2014 in our PET center. The final confirmation of cancer was based on pathologic examination and follow-up after more than 1 year.Among the 97 participants, 92 were asymptomatic and 5 presented with previously diagnosed cancers. Six of the 92 asymptomatic participants (6.6%) with significant nodular lesions were referred for histological or cytological evaluation of the possibility of malignancy, and 1 case was considered clinically important and required surgical resection. The cancer discovery rate was 3.3% (3/92) with positive predictive value of 50% (3/6). In the 5 participants with previously identified cancers, no recurrence or metastasis was detected.The offer of whole-body FDG-PET for cancer screening was welcomed with enthusiasm by most of the hospital employees. PET/CT combines the merits of PET and CT and can be administered to and provide benefits to a select group of hospital employees.

Impact of muscular uptake and statistical noise on tumor quantification based on simulated FDG-PET studies

PurposeThe aim of this work is to study the effect of physiological muscular uptake variations and statistical noise on tumor quantification in FDG-PET studies. MethodsWe designed a realistic framework based on simulated FDG-PET acquisitions from an anthropomorphic phantom that included different muscular uptake levels and three spherical lung lesions with diameters of 31, 21 and 9mm. A distribution of muscular uptake levels was obtained from 136 patients remitted to our center for whole-body FDG-PET. Simulated FDG-PET acquisitions were obtained by using the Simulation System for Emission Tomography package (SimSET) Monte Carlo package. Simulated data was reconstructed by using an iterative Ordered Subset Expectation Maximization (OSEM) algorithm implemented in the Software for Tomographic Image Reconstruction (STIR) library. Tumor quantification was carried out by using estimations of SUVmax, SUV50 and SUVmean from different noise realizations, lung lesions and multiple muscular uptakes. ResultsOur analysis provided quantification variability values of 17–22% (SUVmax), 11–19% (SUV50) and 8–10% (SUVmean) when muscular uptake variations and statistical noise were included. Meanwhile, quantification variability due only to statistical noise was 7–8% (SUVmax), 3–7% (SUV50) and 1–2% (SUVmean) for large tumors (>20mm) and 13% (SUVmax), 16% (SUV50) and 8% (SUVmean) for small tumors (<10mm), thus showing that the variability in tumor quantification is mainly affected by muscular uptake variations when large enough tumors are considered. In addition, our results showed that quantification variability is strongly dominated by statistical noise when the injected dose decreases below 222MBq. ConclusionsOur study revealed that muscular uptake variations between patients who are totally relaxed should be considered as an uncertainty source of tumor quantification values.

Towards real-time topical detection and characterization of FDG dose infiltration prior to PET imaging

To dynamically detect and characterize 18F-fluorodeoxyglucose (FDG) dose infiltrations and evaluate their effects on positron emission tomography (PET) standardized uptake values (SUV) at the injection site and in control tissue. Investigational gamma scintillation sensors were topically applied to patients with locally advanced breast cancer scheduled to undergo limited whole-body FDG-PET as part of an ongoing clinical study. Relative to the affected breast, sensors were placed on the contralateral injection arm and ipsilateral control arm during the resting uptake phase prior to each patient's PET scan. Time-activity curves (TACs) from the sensors were integrated at varying intervals (0-10, 0-20, 0-30, 0-40, and 30-40min) post-FDG and the resulting areas under the curve (AUCs) were compared to SUVs obtained from PET. In cases of infiltration, observed in three sensor recordings (30%), the injection arm TAC shape varied depending on the extent and severity of infiltration. In two of these cases, TAC characteristics suggested the infiltration was partially resolving prior to image acquisition, although it was still apparent on subsequent PET. Areas under the TAC 0-10 and 0-20min post-FDG were significantly different in infiltrated versus non-infiltrated cases (Mann-Whitney, p < 0.05). When normalized to control, all TAC integration intervals from the injection arm were significantly correlated with SUVpeak and SUVmax measured over the infiltration site (Spearman ρ ≥ 0.77, p < 0.05). Receiver operating characteristic (ROC) analyses, testing the ability of the first 10min of post-FDG sensor data to predict infiltration visibility on the ensuing PET, yielded an area under the ROC curve of 0.92. Topical sensors applied near the injection site provide dynamic information from the time of FDG administration through the uptake period and may be useful in detecting infiltrations regardless of PET image field of view. This dynamic information may also complement the static PET image to better characterize the true extent of infiltrations.

Rare Case of Hepatic Gaucheroma in a Child on Enzyme Replacement Therapy.

We present a 6 year old boy with type I Gaucher treated from 16 months with ERT, developing focal Gaucheroma in the liver at 3.5 years. The subject presented at 13 months of age with anaemia, thrombocytopenia and hepatosplenomegaly. Gaucher disease was confirmed by leucocyte enzyme assay. A homozygous change: c.1193G>A (p.Arg398Gln) in the GBA gene was identified. He had normal neurology with normal saccades. Imiglucerase was administered at 60IU/kg/fortnight from 15 months as per Australian regulations with good clinical response. At 3.5 years hepatic ultrasound demonstrated a nodular cystic lesion measuring 7 × 5.3 × 5.1cm in the right lobe of liver, confirmed on MRI. Biopsy demonstrated acellular hyaline necrosis, portal-portal bridging fibrosis and nodules of Gaucher cells. Cystic fluid comprised necrotic debris and Gaucher cells. Further evaluation over 18 months including repeat MRI, biopsy, alpha-fetoprotein monitoring and whole-body FDG-Pet scan demonstrate no malignancy. GD is the most common lysosomal storage disorder. The aetiology, natural history and optimal management strategy of rare Gaucheroma in paediatric cases has not been defined particularly in regards to malignancy risk.

Intravascular large B-Cell lymphoma (IVLBCL) presenting as lumbosacral polyradiculopathy

Background: IVLBCL is potentially treatable but difficult to diagnose. Methods: A case of progressive leg weakness and sphincter dysfunction diagnosed only at autopsy. Results: A 72 year old female presented with three weeks of increasing leg weakness and three days of urine and stool incontinence. Electrophysiological testing showed reduced tibial and peroneal CMAPs, preserved sural SNAPs, and bilateral gastrocnemius fibrillations, consistent with a pre-ganglionic lesion. Lumbosacral MRI with gadolinium showed no abnormalities. CSF was examined three times (protein 1.18-1.25, glucose 2.6-3.1, normal cell count and cytology). Whole-body FDG PET scanning showed hypermetabolic foci at the tongue base and in the mediastinum, but biopsy of both revealed no abnormality. Leg weakness progressed over three months and spread to the arms despite a course of IVIg. Four months later she died of cardiorespiratory arrest. Autopsy revealed the presence of large atypical B-cells within the lumen of small and medium sized vessels in numerous organs. There was evidence of anterior spinal artery obstruction with lymphocytes and anterior horn infarction in the lumbar cord. Conclusions: Although the literature reports that IVLBCL responds well to chemotherapy, this patient illustrates the difficulty of ante-mortem diagnosis. Nerve root biopsy may be warranted in such patients.

Derivation of the scan time requirement for maintaining a consistent PET image quality

Objectives: the image quality of PET for larger patients is relatively poor, even though the injection dose is optimized considering the NECR characteristics of the PET scanner. This poor image quality is due to the lower level of maximum NECR that can be achieved in these large patients. The aim of this study was to optimize the PET scan time to obtain a consistent PET image quality regardless of the body size, based on the relationship between the patient specific NECR (pNECR) and body weight.Methods: eighty patients (M/F=53/27, body weight: 059 ± 1 kg) underwent whole-body FDG PET scans using a Philips GEMINI GS PET/CT scanner after an injection of 0.14 mCi/kg FDG. The relationship between the scatter fraction (SF) and body weight was determined by repeated Monte Carlo simulations using a NEMA scatter phantom, the size of which varied according to the relationship between the abdominal circumference and body weight. Using this information, the pNECR was calculated from the prompt and delayed PET sinograms to obtain the prediction equation of NECR vs. body weight. The time scaling factor (FTS) for the scan duration was finally derived to make PET images with equivalent SNR levels.Results: the SF and NECR had the following nonlinear relationships with the body weight: SF=0.15 ⋅ body weight0.3 and NECR = 421.36 (body weight)−0.84. The equation derived for FTS was 0.01⋅ body weight + 0.2, which means that, for example, a 120-kg person should be scanned 1.8 times longer than a 70 kg person, or the scan time for a 40-kg person can be reduced by 30%.Conclusion: the equation of the relative time demand derived in this study will be useful for maintaining consistent PET image quality in clinics.