scholarly journals Density Estimation for Positron Emission Tomography

2005 ◽  
Vol 4 (2) ◽  
pp. 131-141 ◽  
Author(s):  
Barbara Pawlak ◽  
Richard Gordon
Keyword(s):  
Positron Emission Tomography ◽  
Density Estimation ◽  
3D Imaging ◽  
Diagnostic Techniques ◽  
Emission Tomography ◽  
Experimental Phase ◽  
Positron Emission ◽  
Coincidence Event ◽  
The Mean ◽  
Traditional Approaches

PET (positron emission tomography) scans are still in the experimental phase, as one of the newest breast cancer diagnostic techniques. There are two traditional approaches to the computation of images from data collected in PET. In the first, standard CT (computed tomography) algorithms are used on rays designated by pairs of detectors receiving coincidence events. The problem generated by this approach is that generally only the mean can be used by such algorithms. With the relatively small numbers of events in PET, and with Poisson statistics for which variance equals the mean, the noise sensivity of standard CT algorithms becomes limiting. This is exasperated further by 3D imaging with cylindrical arrays of detectors. Statistical CT algorithms take the variance into account. As in the list-mode approach, we consider each coincidence event individually. However, we estimate the location of the annihilation event that caused each coincidence event, one by one, based on the previously assigned location of events processed earlier. The estimated annihilation locations form the image. To accomplish this, we construct a probability distribution along each coincidence line. This is generated from previous annihilation points by density estimation. In this paper we present our density estimation approach to positron emission tomography. Nonparametric methods of density estimation are overviewed followed by numerical examples. Our goal here is to determine which density estimation approach is most suitable for PET.

Usefulness of positron emission tomography for differentiating gliomas according to the 2016 World Health Organization classification of tumors of the central nervous system

2020 ◽  
Vol 133 (4) ◽  
pp. 1010-1019 ◽  
Author(s):  
Hiroaki Takei ◽  
Jun Shinoda ◽  
Soko Ikuta ◽  
Takashi Maruyama ◽  
Yoshihiro Muragaki ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Who Classification ◽  
Standardized Uptake Value ◽  
Emission Tomography ◽  
World Health ◽  
Pet Tracers ◽  
Positron Emission ◽  
Significant Difference ◽  
The Mean

OBJECTIVEPositron emission tomography (PET) is important in the noninvasive diagnostic imaging of gliomas. There are many PET studies on glioma diagnosis based on the 2007 WHO classification; however, there are no studies on glioma diagnosis using the new classification (the 2016 WHO classification). Here, the authors investigated the relationship between uptake of 11C-methionine (MET), 11C-choline (CHO), and 18F-fluorodeoxyglucose (FDG) on PET imaging and isocitrate dehydrogenase (IDH) status (wild-type [IDH-wt] or mutant [IDH-mut]) in astrocytic and oligodendroglial tumors according to the 2016 WHO classification.METHODSIn total, 105 patients with newly diagnosed cerebral gliomas (6 diffuse astrocytomas [DAs] with IDH-wt, 6 DAs with IDH-mut, 7 anaplastic astrocytomas [AAs] with IDH-wt, 24 AAs with IDH-mut, 26 glioblastomas [GBMs] with IDH-wt, 5 GBMs with IDH-mut, 19 oligodendrogliomas [ODs], and 12 anaplastic oligodendrogliomas [AOs]) were included. All OD and AO patients had both IDH-mut and 1p/19q codeletion. The maximum standardized uptake value (SUV) of the tumor/mean SUV of normal cortex (T/N) ratios for MET, CHO, and FDG were calculated, and the mean T/N ratios of DA, AA, and GBM with IDH-wt and IDH-mut were compared. The diagnostic accuracy for distinguishing gliomas with IDH-wt from those with IDH-mut was assessed using receiver operating characteristic (ROC) curve analysis of the mean T/N ratios for the 3 PET tracers.RESULTSThere were significant differences in the mean T/N ratios for all 3 PET tracers between the IDH-wt and IDH-mut groups of all histological classifications (p < 0.001). Among the 27 gliomas with mean T/N ratios higher than the cutoff values for all 3 PET tracers, 23 (85.2%) were classified into the IDH-wt group using ROC analysis. In DA, there were no significant differences in the T/N ratios for MET, CHO, and FDG between the IDH-wt and IDH-mut groups. In AA, the mean T/N ratios of all 3 PET tracers in the IDH-wt group were significantly higher than those in the IDH-mut group (p < 0.01). In GBM, the mean T/N ratio in the IDH-wt group was significantly higher than that in the IDH-mut group for both MET (p = 0.034) and CHO (p = 0.01). However, there was no significant difference in the ratio for FDG.CONCLUSIONSPET imaging using MET, CHO, and FDG was suggested to be informative for preoperatively differentiating gliomas according to the 2016 WHO classification, particularly for differentiating IDH-wt and IDH-mut tumors.

Hyperosmolar blood-brain barrier disruption in baboons: an in vivo study using positron emission tomography and rubidium-82

1996 ◽  
Vol 84 (3) ◽  
pp. 494-502 ◽  
Author(s):  
Bernhard Zünkeler ◽  
Richard E. Carson ◽  
Jeffrey Olson ◽  
Ronald G. Blasberg ◽  
Mary Girton ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Emission Tomography ◽  
Brain Barrier ◽  
Blood Brain ◽  
Positron Emission ◽  
The Mean ◽  
Rubidium 82

✓ Hyperosmolar blood-brain barrier (BBB) disruption remains controversial as an adjuvant therapy to increase delivery of water-soluble compounds to extracellular space in the brain in patients with malignant brain tumors. To understand the physiological effects of BBB disruption more clearly, the authors used positron emission tomography (PET) to study the time course of BBB permeability in response to the potassium analog rubidium-82 (82Rb, halflife 75 seconds) following BBB disruption in anesthetized adult baboons. Mannitol (25%) was injected into the carotid artery and PET scans were performed before and serially at 8- to 15-minute intervals after BBB disruption. The mean influx constant (K1), a measure of permeability-surface area product, in ipsilateral, mannitol-perfused mixed gray- and white-matter brain regions was 4.9 ± 2.4 µl/min/ml (± standard deviation) at baseline and increased more than 100% (ΔK1 = 9.4 ± 5.1 µl/min/ml, 18 baboons) in brain perfused by mannitol. The effect of BBB disruption on K1 correlated directly with the total amount of mannitol administered (p < 0.005). Vascular permeability returned to baseline with a halftime of 24.0 ± 14.3 minutes. The mean brain plasma volume rose by 0.57 ± 0.34 ml/100 ml in ipsilateral perfused brain following BBB disruption. This work provides a basis for the in vivo study of permeability changes induced by BBB disruption in human brain and brain tumors.

scholarly journals Positron Emission Tomography-Computed Tomography Parameters Predict Efficacy of Immunotherapy in Head and Neck Squamous Cell Carcinomas

2021 ◽  
Vol 11 ◽  
Author(s):  
Songtao Zhang ◽  
Runfang Zhang ◽  
Wenbo Gong ◽  
Chao Wang ◽  
Chen Zeng ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Survival Analysis ◽  
Head And Neck ◽  
Clinical Response ◽  
Squamous Cell ◽  
Emission Tomography ◽  
Positron Emission ◽  
The Mean ◽  
The Difference

BackgroundThis study aims to assess the association between positron emission tomography-computed tomography (PET-CT) parameters and the response to immune checkpoint inhibitors in unresectable head and neck squamous cell carcinoma (HNSCC).MethodsA total of 105 patients receiving immunotherapy (pembrolizumab or sintilimab with/without cisplatin) were retrospectively enrolled in this study; pretreatment data regarding metabolic tumor volume (MTV) and maximum standardized uptake value (SUVmax) were collected. The primary interest of the study was objective response rate (ORR), and the secondary was progression−free survival (PFS).ResultsThe mean total MTV was 40.6 cm3 (range: 8.5–100.3), ORRs in tumors with total MTV of ≥40.6 and &lt;40.6 cm3 were 43.1% and 23.1%, respectively; the difference was statistically significant (p = 0.018). Survival analysis indicated similar PFS rates in the two groups (p = 0.057). The mean total SUVmax was 12.5, ORRs in tumors with total SUVmax ≥12.5 and &lt;12.5 were 40.0% and 26.0%, respectively; the difference was not significant (p = 0.092). Survival analysis reported patients with total SUVmax of ≥12.5 had significantly worse PFS (p = 0.001) than patients with total SUVmax of &lt;12.5.ConclusionsIn HNSCC, total MTV ≥40.6 cm3 translated into improved clinical response but not into better PFS; total SUVmax had no effect on clinical response, but total SUVmax ≥12.5 was associated with worse PFS.

A Pilot Study of [18F]Fluorodeoxyglucose Positron Emission Tomography Scans During and After Radiation-Based Therapy in Patients With Non–Small-Cell Lung Cancer

2007 ◽  
Vol 25 (21) ◽  
pp. 3116-3123 ◽  
Author(s):  
Feng-Ming Spring Kong ◽  
Kirk A. Frey ◽  
Leslie E. Quint ◽  
Randall K. Ten Haken ◽  
James A. Hayman ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Positron Emission Tomography ◽  
Metabolic Response ◽  
Small Cell ◽  
Emission Tomography ◽  
Fluorodeoxyglucose Positron Emission Tomography ◽  
Small Cell Lung ◽  
Positron Emission ◽  
The Mean ◽  
Fluorodeoxyglucose Positron Emission

Purpose To study whether changes of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) during treatment correlate with post-treatment responses in tumor and normal lung in patients with non–small-cell lung cancer (NSCLC). Patients and Methods Patients with stage I to III NSCLC requiring a definitive dose of fractionated radiation therapy (RT) were eligible. FDG-PET/computed tomography scans were acquired before, during, and after RT. Tumor and lung metabolic responses were assessed qualitatively by physicians and quantitatively by normalized peak FDG activity (the ratio of the maximum FDG activity divided by the mean of the aortic arch background). Results The study reached the goal of recruiting 15 patients between February 2004 and August 2005. Of these, 11 patients had partial metabolic response, two patients had complete metabolic response, and two patients had stable disease at approximately 45 Gy during RT. The mean peak tumor FDG activity was 5.2 (95% CI, 4.0 to 6.4), 2.5 (95% CI, 2.0 to 3.0), and 1.7 (95% CI, 1.3 to 2.0) on pre-, during, and post-RT scans, respectively. None of the patients had appreciable changes in the lung during RT. The peak FDG activity of the lung was 0.47 (95% CI, 0.36 to 0.59), 0.52 (95% CI, 0.40 to 0.64), and 1.29 (95% CI, 0.82 to 1.76), on pre-, during-, and post-RT scans, respectively. The qualitative response during RT correlated with the overall response post-RT (P = .03); the peak tumor FDG activity during RT correlated with those 3 months post-RT (R2 = 0.7; P < .001). Conclusion This pilot study suggests a significant correlation in tumor metabolic response and no association in lung FDG activity between during RT scans and 3 months post-RT scans in patients with NSCLC. Additional study with a large number of patients is needed to validate these findings.

scholarly journals Positron Emission Tomography as a Surrogate Marker for Evaluation of Treatment Response in Patients with Desmoid Tumors under Therapy with Imatinib

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Bernd Kasper ◽  
Antonia Dimitrakopoulou-Strauss ◽  
Lothar R. Pilz ◽  
Ludwig G. Strauss ◽  
Christos Sachpekidis ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Progressive Disease ◽  
Surrogate Marker ◽  
Standardized Uptake Value ◽  
Response Prediction ◽  
Emission Tomography ◽  
Desmoid Tumors ◽  
Positron Emission ◽  
The Mean ◽  
Magnetic Resonance Imaging Mri

We used 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography (PET) to evaluate patients with desmoid tumors undergoing therapy with imatinib. The study included 22 patients with progressive disease (PD) of a biopsy proven desmoid tumor treated orally with imatinib 800 mg daily. Patients were examined using PET prior to onset of therapy and during treatment. Restaging was performed in parallel using computed tomography (CT) and/or magnetic resonance imaging (MRI). Outcome of 22 evaluable patients was as follows: five patients with partial response (PR); twelve patients with stable disease (SD) accounting for 77% with non-progressive disease; five patients showed PD. A 30% decrease of the mean average standardized uptake value (SUV) of sequential PET examinations could be demonstrated; no patient demonstrated a substantial increase in SUV. Patients with PR/SD were matched to a group of nonprogressive disease and tested versus PD. The initial average SUV and seem to be candidates for a response prediction with an approximate -value of0.06553and0.07785, respectively. This is the first larger series of desmoid patients monitored using PET showing that early SUV changes may help to discriminate responders from nonresponders and, thus, to decide whether imatinib therapy should be continued.

The Relevance of Increased Tonsil Uptake When Restaging Lymphoma with Positron Emission Tomography

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3133-3133
Author(s):  
Javier Munoz ◽  
Belisario Arango ◽  
Jessica Schering ◽  
James Morrison ◽  
Ishani Dalal ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Conflicts Of Interest ◽  
Standardized Uptake Value ◽  
Emission Tomography ◽  
Invasive Approach ◽  
Fdg Uptake ◽  
Tonsillar Tissue ◽  
Positron Emission ◽  
Lymphomatous Involvement ◽  
The Mean

Abstract Abstract 3133 Introduction: Significant tonsil uptake is sometimes observed in F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) after treatment. Some patients undergo tonsillectomy or FNA (fine needle aspiration) to rule out malignant involvement particularly when management depends on restaging (Figure 1). Our study describes the incidence and degree of tonsil FDG uptake in a large group of lymphoma patients that underwent PET scanning. Patients and Methods: Single institution, retrospective chart review by ICD code, 617 lymphoma patients that underwent PET at our institution from 2004 to 2009. Results of PET were compared to pathological diagnosis of tonsillectomy (Table 1) or FNA biopsy (Table 2) when available which was performed at physician's discretion. Patients that were diagnosed with lymphoma during restaging studies performed for a different primary malignancy were excluded. Results and Discussion: All 8 tonsillectomies and FNA biopsies performed after a restaging PET that showed increased tonsil uptake were negative for malignancy (Figure 2). All of these 8 patients had an initial previous PET that did not show increased tonsil uptake and also these 8 patients remained in remission from their lymphoma after the procedure was performed. In contrast, 6 out of 7 patients that underwent tonsillectomy or FNA at diagnosis were positive for malignancy (Table 3). Differences among tonsil FDG uptake has been thought to reflect differences in activity of “physiological” inflammation of the palatine tonsils. Increased glucose metabolism during active inflammation in the case of chronic tonsillitis or lymphocyte proliferation in the case of a patient that has received prior chemotherapy (likely experiencing compensatory extra medullar lymphoid hyperplasia) were thought to be causes of high FDG uptake in the tonsils. The significance of such increased tonsil FDG uptake is currently unknown however previous studies suggest that normal pharyngeal palatine tonsil uptake was generally symmetrical and that the difference in maximal standardized uptake value (SUVmax) between right and left tonsils (right-to-left ratio or a surrogate of symmetry) in the same patient might be helpful in detecting malignant tissue. The mean right-to-left ratio of tonsillar SUV was 4.55 in patients with confirmed malignant pathology and 1.53 in patients with documented benign tonsillar tissue (Table 4). The mean tonsillar SUVmax was 15.35 in patients with confirmed malignant pathology and 7.05 in patients with documented benign tonsillar tissue hence SUVmax seems to be useful in differentiating tumor from physiological accumulation. Younger patients with low SUV max symmetric tonsillar uptake and no other abnormal FDG areas seen during restaging PET could probably be watched non-invasively. Conclusions: At the time of initial staging PET, increased tonsil uptake showed true lymphomatous involvement in most cases. At restaging, increased tonsil uptake displayed no cases positive for lymphomatous involvement as all tonsillectomies and FNA biopsies were negative for malignancy. These findings seem to be valid irrespective of the subtype of lymphoma. Our study supports a conservative non-invasive approach because physiologic uptake is the most common cause of increased tonsil uptake when restaging lymphoma patients after treatment has been completed. Disclosures: No relevant conflicts of interest to declare.

Assessing short-term effects and costs at an early stage of innovation: The use of positron emission tomography on radiotherapy treatment decision making

2008 ◽  
Vol 24 (02) ◽  
pp. 212-220 ◽  
Author(s):  
Raphaël Remonnay ◽  
Magali Morelle ◽  
Pascal Pommier ◽  
Francesco Giammarile ◽  
Marie-Odile Carrère
Keyword(s):  
Lung Cancer ◽  
Decision Making ◽  
Positron Emission Tomography ◽  
Hodgkin's Disease ◽  
Hodgkin’S Disease ◽  
Emission Tomography ◽  
Positron Emission ◽  
The Mean ◽  
Mean Cost ◽  
Radiotherapy Treatment

Objectives:Positron emission tomography (PET) is an innovative imaging tool. Associated with computed tomography (CT), it allows a better definition for the tumor volume for radiotherapy, compared with CT only. The aim of this study was to assess the effects of PET on resource allocation (costs and savings) and on the choice of the following treatment in radiotherapy.Methods:In 2004 and 2005, 209 patients were enrolled (97 patients with Hodgkin's disease and 112 with non-small cell lung cancer) in a national study conducted in eight hospitals. Two treatment decisions made on the basis of CT only or CT associated with PET, were compared in a prospective study where each subject was his/her own control. The direct medical cost of using PET was assessed by microcosting, using data collected from specific questionnaires. The costs of new tests and the costs and savings associated with changes in the chosen treatment were calculated on the basis of reimbursement rates.Results:The mean cost of using PET was approximately €800 per patient (50 percent for the radionuclide18F-FDG [2-[18F]fluoro-2-deoxy-D-glucose]). Radiotherapy treatments were modified for 10 percent of patients with Hodgkin's disease versus 40 percent of patients with lung cancer. Overall, the use of PET induced both increases and decreases in the mean cost per patient: the net effect was a €425 and €931 cost increase in lung cancer and Hodgkin's disease, respectively.Conclusions:The use of PET for radiotherapy decision making seems more valuable for lung cancer than for Hodgkin's disease, both in terms of costs and changes in radiotherapy treatment. This result might help policy makers for prioritization.

scholarly journals Calculation of the FDG Lumped Constant by Simultaneous Measurements of Global Glucose and FDG Metabolism in Humans

1998 ◽  
Vol 18 (2) ◽  
pp. 154-160 ◽  
Author(s):  
Steen G. Hasselbalch ◽  
Peter L. Madsen ◽  
Gitte M. Knudsen ◽  
Søren Holm ◽  
Olaf B. Paulson
Keyword(s):  
Positron Emission Tomography ◽  
Conversion Factor ◽  
Venous Blood ◽  
Mean Value ◽  
Emission Tomography ◽  
Brain Glucose ◽  
Positron Emission ◽  
Lumped Constant ◽  
Net Uptake ◽  
The Mean

The lumped constant defined as the conversion factor between the net uptake of fluoro-2-deoxy-D-glucose (FDG) and glucose was calculated from global CMRglc and from positron emission tomography (PET) using FDG as tracer (CMRFDG). Fifteen healthy, normal volunteers (mean age 24 ± 4 years) were studied. Global CBF and CMRglc were measured with the Kety-Schmidt technique using 133Xe as tracer, and values were corrected for errors from incomplete diffusion equilibrium for inert gas tracer between brain tissue and cerebral venous blood. Measurements of CMRFDG were obtained with PET using the dynamic and single-scan methods and the K1–k3 model. Measurements with the Kety-Schmidt technique and PET-FDG were performed simultaneously. Global CBF was 47.1 ± 8.0 mL · 100 g−1 · min−1, and CMRglc was 22.8 ± 4.1 μmol · 100 g−1 · min−1. No difference in CMRFDG was found with the two methods (17.8 ± 1.6 and 18.2 ± 1.3 μmol · 100 g−1 · min−1, dynamic and single scan methods, respectively). Accordingly, the lumped constant ranged from 0.80 ± 0.16 to 0.82 ± 0.15, with a mean value of 0.81 ± 0.15. The mean ratio between phosphorylation of FDG and glucose (k3*/k3) was 0.39 ± 0.25. The discrepancy between the lumped constant determined in this study and previously obtained values can be explained partly by methodologic problems, and we conclude that most of the discrepancy results from previous overestimation of global CBF. Key Words: Positron emission tomography—18F-Fluro-deoxy-D-glucose—Lumped constant—Brain glucose metabolism.

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