Integrated Positron Emission Tomography Research Articles

A Tumor Volume Segmentation Algorithm Based on Radiomics Features in FDG-PET in Lung Cancer Patients, Validated Using Surgical Specimens

Background: Although the integration of positron emission tomography into radiation therapy treatment planning has become part of clinical routine, the best method for tumor delineation is still a matter of debate. In this study, therefore, we analyzed a novel, radiomics-feature-based algorithm in combination with histopathological workup for patients with non-small-cell lung cancer. Methods: A total of 20 patients with biopsy-proven lung cancer who underwent [18F]fluorodeoxyglucose positron emission/computed tomography (FDG-PET/CT) examination before tumor resection were included. Tumors were segmented in positron emission tomography (PET) data using previously reported algorithms based on three different radiomics features, as well as a threshold-based algorithm. To obtain gold-standard results, lesions were measured after resection. Pathological volumes and maximal diameters were then compared with the results of the segmentation algorithms. Results: A total of 20 lesions were analyzed. For all algorithms, segmented volumes correlated well with pathological volumes. In general, the threshold-based volumes exhibited a tendency to be smaller than the radiomics-based volumes. For all lesions, conventional threshold-based segmentation produced coefficients of variation which corresponded best with pathologically based volumes; however, for lesions larger than 3 ccm, the algorithm based on Local Entropy performed best, with a significantly better coefficient of variation (p = 0.0002) than the threshold-based algorithm. Conclusions: We found that, for small lesions, results obtained using conventional threshold-based segmentation compared well with pathological volumes. For lesions larger than 3 ccm, the novel algorithm based on Local Entropy performed best. These findings confirm the results of our previous phantom studies. This algorithm is therefore worthy of inclusion in future studies for further confirmation and application.

What is new in imaging to assist in the diagnosis of giant cell arteritis and Takayasu's arteritis since the EULAR and ACR/VF recommendations?

Over the past decades, fundamental insights have been gained to establish the pivotal role of imaging in the diagnosis of large-vessel vasculitis, including giant cell arteritis (GCA) and Takayasu's arteritis (TAK). A deeper comprehension of imaging modalities has prompted earlier diagnosis leading to expedited treatment for better prognosis. The European Alliance of Associations in Rheumatology (EULAR) recommended in 2023 that ultrasound should be the initial imaging test in suspected GCA, and Magnetic Resonance Imaging (MRI) remains the first-line imaging modality in suspected TAK. We summarize the recent advances in diagnostic imaging in large vessel vasculitis, highlighting use of combination imaging modalities, and discuss progress in newer imaging techniques such as contrast-enhanced ultrasound, shear wave elastography, ocular ultrasound, ultrasound biomicroscopy, integration of Positron Emission Tomography (PET) with MRI, novel tracer in PET, black blood MRI, orbital MRI, and implementation of artificial intelligence (AI) to existing imaging modalities. Our aim is to offer a perspective on ongoing advancements in imaging for the diagnosis of GCA and TAK, particularly innovative technology, which could potentially boost diagnostic precision.

Cyclotron production of manganese-52: a promising avenue for multimodal PET/MRI imaging

BackgroundThe integration of positron emission tomography (PET) and magnetic resonance imaging (MRI) holds promise for advancing diagnostic imaging capabilities. The METRICS project aims to develop cyclotron-driven production of 52Mn for PET/MRI imaging.ResultsUsing the 52Cr(p,n)52Mn reaction, we designed chromium metal targets via Spark Plasma Sintering and developed a separation procedure for isolating 52Mn. Labeling tests were conducted with traditional chelators (i.e. S-2-(4-Isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid) and the 1.4-dioxa-8-azaspiro[4.5]decane-8- carbodithioate ligand to produce radioactive complexes suitable for PET/MRI applications. Our methodology yielded high-quality 52Mn suitable for PET radiopharmaceuticals and PET/MRI imaging. Preliminary studies on phantom imaging using microPET and clinical MRI demonstrated the efficacy of our approach.ConclusionsThe developed technology offers a promising avenue for producing 52Mn and enhancing PET/MRI imaging capabilities. Further in vivo investigations are warranted to evaluate the potential advantages of this hybrid imaging technique.

Value of Molecular Typing Combined with Integrated Positron Emission Tomography/Magnetic Resonance Imaging in Risk Stratification of Endometrial Cancer.

In this study, we investigated the value of molecular typing combined with integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) semi-quantitative indices in endometrial cancer risk stratification. A retrospective study was conducted on 86 patients who were pathologically diagnosed with endometrial cancer and underwent surgical treatment after curettage at the Department of Obstetrics and Gynecology, Xuanwu Hospital, Capital Medical University between January 2017 and March 2023. Prior to surgery, each patient underwent integrated PET/MRI examination. The postoperative samples were subjected to pathological diagnosis, immunohistochemistry, and POLE gene sequencing. The differences in clinicopathological features between the four molecular subtypes and the differences in integrated PET/MRI semi-quantitative indexes (SUV max, ADC min) between the four molecular subtypes were analyzed. The cutoff value of molecular typing combined with integrated PET/MRI semi-quantitative indices for endometrial cancer risk stratification was determined. There were statistically significant differences in pathological types and tumor grades among the four molecular subtypes of endometrial cancer. The values of the four integrated PET/MRI semi-quantitative indices (SUV max and ADC min) of the molecular subtypes were statistically different. The SUV max was greater in the p53abn mutation group than in the POLE mutation group (P < 0.05). The ADC minimum of the POLE mutation group and the MMR-d group was lower than the NSMP group (P <0.05). Molecular typing combined with the integrated PET/MRI semi-quantitative SUV max index can predict the low/medium risk group of endometrial cancer and the medium-high/high risk group, and the cut-off value of SUV max for predicting the risk of early endometrial cancer was 14.72 (sensitivity 66.7%, specificity 68.7%). Molecular typing combined with integrated PET/MRI semi-quantitative indicators is useful to achieve risk stratification in patients diagnosed with endometrial cancer and guide individualized treatment.

Neuroimmune activation and increased brain aging in chronic pain patients after the COVID-19 pandemic onset

The COVID-19 pandemic has exerted a global impact on both physical and mental health, and clinical populations have been disproportionally affected. To date, however, the mechanisms underlying the deleterious effects of the pandemic on pre-existing clinical conditions remain unclear. Here we investigated whether the onset of the pandemic was associated with an increase in brain/blood levels of inflammatory markers and MRI-estimated brain age in patients with chronic low back pain (cLBP), irrespective of their infection history. A retrospective cohort study was conducted on 56 adult participants with cLBP (28 ‘Pre-Pandemic’, 28 ‘Pandemic’) using integrated Positron Emission Tomography/ Magnetic Resonance Imaging (PET/MRI) and the radioligand [11C]PBR28, which binds to the neuroinflammatory marker 18 kDa Translocator Protein (TSPO). Image data were collected between November 2017 and January 2020 (‘Pre-Pandemic’ cLBP) or between August 2020 and May 2022 (‘Pandemic’ cLBP). Compared to the Pre-Pandemic group, the Pandemic patients demonstrated widespread and statistically significant elevations in brain TSPO levels (P =.05, cluster corrected). PET signal elevations in the Pandemic group were also observed when 1) excluding 3 Pandemic subjects with a known history of COVID infection, or 2) using secondary outcome measures (volume of distribution -VT- and VT ratio - DVR) in a smaller subset of participants. Pandemic subjects also exhibited elevated serum levels of inflammatory markers (IL-16; P <.05) and estimated BA (P <.0001), which were positively correlated with [11C]PBR28 SUVR (r’s ≥ 0.35; P’s < 0.05). The pain interference scores, which were elevated in the Pandemic group (P <.05), were negatively correlated with [11C]PBR28 SUVR in the amygdala (r = −0.46; P<.05).This work suggests that the pandemic outbreak may have been accompanied by neuroinflammation and increased brain age in cLBP patients, as measured by multimodal imaging and serum testing. This study underscores the broad impact of the pandemic on human health, which extends beyond the morbidity solely mediated by the virus itself.

Association of protein distribution and gene expression revealed by positron emission tomography and postmortem gene expression in the dopaminergic system of the human brain.

The topological distribution of dopamine-related proteins is determined by gene transcription and subsequent regulations. Recent research strategies integrating positron emission tomography with a transcriptome atlas have opened new opportunities to understand the influence of regulation after transcription on protein distribution. Previous studies have reported that messenger (m)-RNA expression levels spatially correlate with the density maps of serotonin receptors but not with those of transporters. This discrepancy may be due to differences in regulation after transcription between presynaptic and postsynaptic proteins, which have not been studied in the dopaminergic system. Here, we focused on dopamine D1 and D2/D3 receptors and dopamine transporters and investigated their region-wise relationship between mRNA expression and protein distribution. We examined the region-wise correlation between regional binding potentials of the target region relative to that of non-displaceable tissue (BPND) values of 11C-SCH-23390 and mRNA expression levels of dopamine D1 receptors (D1R); regional BPND values of 11C-FLB-457 and mRNA expression levels of dopamine D2/D3 receptors (D2/D3R); and regional total distribution volume (VT) values of 18F-FE-PE2I and mRNA expression levels of dopamine transporters (DAT) using Spearman's rank correlation. We found significant positive correlations between regional BPND values of 11C-SCH-23390 and the mRNA expression levels of D1R (r = 0.769, p = 0.0021). Similar to D1R, regional BPND values of 11C-FLB-457 positively correlated with the mRNA expression levels of D2R (r = 0.809, p = 0.0151) but not with those of D3R (r = 0.413, p = 0.3095). In contrast to D1R and D2R, no significant correlation between VT values of 18F-FE-PE2I and mRNA expression levels of DAT was observed (r = -0.5934, p = 0.140). We found a region-wise correlation between the mRNA expression levels of dopamine D1 and D2 receptors and their respective protein distributions. However, we found no region-wise correlation between the mRNA expression levels of dopamine transporters and their protein distributions, indicating different regulatory mechanisms for the localization of pre- and postsynaptic proteins. These results provide a broader understanding of the application of the transcriptome atlas to neuroimaging studies of the dopaminergic nervous system.

Factors predict the adequacy of cervical mediastinoscopy in nonsmall cell lung carcinoma lymph node staging and comparison computed tomography and integrated positron emission tomography

Background Standard cervical mediastinoscopy (SCM) has traditionally been considered the reference standard for grading mediastinal involvement in lung cancer. The objective of this research is to evaluate the impact of surgeon experience and patient-related restrictions on the adequacy of mediastinal lymph node (LN) sampling. Additionally, we aim to assess the effectiveness of PET/computed tomography (CT) in comparison to ECM (extended cervical mediastinoscopy), particularly in identifying metastases in the aortopulmonary window (APW) LN. Methods This prospective cohort study involved sixty individuals diagnosed with nonsmall cell lung cancer (NSCLC). The participants underwent fine needle transthoracic aspiration biopsy or bronchoscopy and subsequently had ECM performed. All participants underwent various diagnostic procedures, including thoracic CT, posteroanterior chest radiograph, pulmonary function tests, PET/CT, electrocardiography, cranial magnetic resonance imaging, and laboratory investigations. Results In terms of our outcomes, we evaluated the specificity, positive predictive value (PPV), sensitivity, negative predictive value (NPV), and accuracy of ECM. The results for ECM were as follows specificity of 100.0%, PPV of 100.0%, sensitivity of 78.3%, NPV of 88.1%, and accuracy of 91.7%. For PET/CT, the results were: a specificity of 90.5%, PPV of 75.0%, sensitivity of 57.1%, NPV of 80.9%, and accuracy of 78.3%. Conclusion The ECM procedure is highly beneficial in identifying APW LN metastasis in individuals diagnosed with nonsmall cell lung cancer. It exhibits a favorable NPV and efficiency. Moreover, it can be easily performed by a team with the necessary experience.

Diagnostic performance of FDG PET/MRI for cervical lymph node metastasis in patients with clinically N0 head and neck cancer.

Treatment management in cases of head and neck squamous cell cancer (HNSCC) that are clinically negative for lymph node metastases (cN0) is still an important topic of discussion. There is increasing interest in sensitive imaging modalities that can detect the risk of occult metastases at levels below 20%. This study aimed to examine the efficacy of integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) in determining neck nodal metastasis status in cN0 patients with HNSCC. In this retrospective study, 44 patients who underwent neck dissection with the diagnosis of HNSCC between January 2018 and August 2020 were analyzed. Clinical examinations, including ultrasonography, were performed to identify cervical metastases in HNSCC patients with preoperative cN0. A nuclear medicine specialist visually evaluated the MRI, PET, and PET/MRI results. Histopathologically, 86.4% of patients were classified as N0. According to the histopathological results, MRI showed 50% sensitivity, 89.5% specificity, 91.8% negative predictive value (NPV), 42.8% positive predictive value (PPV) and 84% accuracy, while PET showed 83.3% sensitivity, 68.4% specificity, 96.2% NPV, 29.4% PPV and 70.4% accuracy. PET/MRI was more successful in distinguishing pathological N0 and N+ patients (83.3% sensitivity, 92.1% specificity, 97.2% NPV, 62.5% PPV and 90.9% accuracy). PET/MRI is more sensitive and has a higher NPV compared to MRI alone, while its sensitivity was found to be comparable to that of PET. In addition, with its ability to detect pathological N0 patients, PET/MRI may significantly decrease the number of unnecessary neck dissections.

The value of 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance whole-body scans and local enhancement scans in the preoperative staging and resectability assessment of pancreatic adenocarcinoma.

In addition to contrast-enhanced multiphase computed tomography (CT) and magnetic resonance imaging (MRI), integrated positron emission tomography (PET)/magnetic resonance (MR) is increasingly being used for the preoperative evaluation of pancreatic cancer. The purpose of this study was to explore the value of hybrid 18F-fluorodeoxyglucose (18F-FDG) PET/MR imaging in preoperative assessment and treatment decision-making. A retrospective data collection (of imaging, clinical, and pathological information) was conducted on patients who underwent 18F-FDG PET/MR with clinically diagnosed or suspected pancreatic cancer from March 2018 to March 2022 in Ruijin Hospital. The data of 76 patients were initially included, with 1 of the 76 patients eventually being excluded due to a misdiagnosis of inflammatory disease. Of the 75 patients, 38 underwent pancreatic tumor resection and 10 underwent laparoscopic exploration. The accuracy of 18F-FDG PET/MR for pancreatic cancer staging and the assessment of pancreatic resectability was evaluated based on pathological results, intraoperative findings, and documented final clinical stages of illness. The adjustments to patient treatment plans were also analyzed before and after 18F-FDG PET/MR examination. The accuracy of clinical tumor node metastasis (TNM) staging of pancreatic cancer by 18F-FDG PET/MR was 73.3% (55/75). The area under the curve (AUC) of 18F-FDG PET/MR for diagnosing the advanced stage (III-IV) versus the nonadvanced stage (I-II) of disease was 0.922 [95% confidence interval (CI): 0.852-0.993]. The treatment regimen of 20.0% (15/75) of patients was impacted. The accuracy of the evaluation of the resectability of pancreatic cancer with 18F-FDG PET/MR was 91.9% (34/37). With the surgical and pathological results being used as a reference, the overall accuracy of preoperative 18F-FDG PET/MR for T staging was 62.2%, and the AUC for diagnosing T4 versus T1-3 was 0.872 (95% CI: 0.660-1.000). 18F-FDG PET/MR performs well in diagnosing advanced pancreatic cancer and thus may impact the treatment decisions for a considerable number of patients. 18F-FDG PET/MR has a high level of accuracy in evaluating the resectability of pancreatic cancer before surgery.

Deep learning model integrating positron emission tomography and clinical data for prognosis prediction in non-small cell lung cancer patients

BackgroundLung cancer is the leading cause of cancer-related deaths worldwide. The majority of lung cancers are non-small cell lung cancer (NSCLC), accounting for approximately 85% of all lung cancer types. The Cox proportional hazards model (CPH), which is the standard method for survival analysis, has several limitations. The purpose of our study was to improve survival prediction in patients with NSCLC by incorporating prognostic information from F-18 fluorodeoxyglucose positron emission tomography (FDG PET) images into a traditional survival prediction model using clinical data.ResultsThe multimodal deep learning model showed the best performance, with a C-index and mean absolute error of 0.756 and 399 days under a five-fold cross-validation, respectively, followed by ResNet3D for PET (0.749 and 405 days) and CPH for clinical data (0.747 and 583 days).ConclusionThe proposed deep learning-based integrative model combining the two modalities improved the survival prediction in patients with NSCLC.

PET/MR imaging of inflammation in atherosclerosis.

Myocardial infarction, stroke, mental disorders, neurodegenerative processes, autoimmune diseases, cancer and the human immunodeficiency virus impact the haematopoietic system, which through immunity and inflammation may aggravate pre-existing atherosclerosis. The interplay between the haematopoietic system and its modulation of atherosclerosis has been studied by imaging the cardiovascular system and the activation of haematopoietic organs via scanners integrating positron emission tomography and resonance imaging (PET/MRI). In this Perspective, we review the applicability of integrated whole-body PET/MRI for the study of immune-mediated phenomena associated with haematopoietic activity and cardiovascular disease, and discuss the translational opportunities and challenges of the technology.

Medication overuse headache associated with decreased dopamine transporter availability in the medial but not in the lateral orbitofrontal cortex: a 11CFT PET/MR study

Backgrounds Dysfunction of the mesocorticolimbic dopamine system in medication overuse headache (MOH) is unknown. This study aimed to determine dopamine transporter (DAT) availability, which is sensitive to dopamine levels, in the mesocorticolimbic dopamine system in MOH patients. Methods This case–control study investigated eligible MOH patients admitted to the International Headache Centre in the neurological department of Chinese PLA General Hospital between July 2018 and August 2019. All subjects underwent an integrated positron emission tomography (PET)/magnetic resonance (MR) brain scans with 11CFT, a radioligand that binds to DAT. Standardised uptake value ratio (SUVr) images were compared voxelwise between MOH patients and healthy controls (HCs). SUVr values from significantly changed regions were extracted, and partial correlation analyses with clinical measures were conducted. Results We examined 17 MOH patients and 16 HCs. MOH patients had lower SUVr levels in the medial rather than lateral orbitofrontal cortex (OFC) than HCs (T = −5.0317, P GRF < 0.01), which showed no correlation with clinical features. Conclusions MOH is characterised by decreased DAT availability in the medial OFC, which might reflect compensatory downregulation due to low dopamine signalling within the mesocorticolimbic dopamine system and provide a new perspective to understand the pathogenesis of MOH.

Assessing the accuracy of [18F]PSMA-1007 PET/CT for primary staging of lymph node metastases in intermediate- and high-risk prostate cancer patients

Background[18F]PSMA-1007 is a promising tracer for integrated positron emission tomography and computed tomography (PET/CT).ObjectiveOur aim was to assess the diagnostic accuracy of [18F]PSMA-1007 PET/CT for primary staging of lymph node metastasis before robotic-assisted laparoscopy (RALP) with extended lymph node dissection (ePLND).Design, Setting and ParticipantsThe study was a retrospective cohort in a tertiary referral center. Men with prostate cancer that underwent surgical treatment for intermediate- or high-risk prostate cancer between May 2019 and August 2021 were included.Interventions[18F]PSMA-1007 PET/CT for initial staging followed by RALP and ePLND.Outcome measurements and statistical analysesSensitivity and specificity were calculated both for the entire cohort and for patients with lymph node metastasis ≥ 3 mm. Positive (PPV) and negative (NPV) predictive values were calculated.Results and limitationsAmong 104 patients included in the analyses, 26 patients had lymph node metastasis based on pathology reporting and metastases were ≥ 3 mm in size in 13 of the cases (50%). In the entire cohort, the sensitivity and specificity of [18F]PSMA-1007 were 26.9% (95% confidence interval (CI); 11.6–47.8) and 96.2% (95% CI; 89.2–99.2), respectively. The sensitivity and specificity of [18F]PSMA-1007 to detect a lymph node metastasis ≥ 3 mm on PET/CT were 53.8% (95% CI; 25.1–80.8) and 96.7% (95% CI; 90.7–99.3), respectively. PPV was 70% and NPV 93.6%.ConclusionsIn primary staging of intermediate- and high-risk prostate cancer, [18F]PSMA-1007 PET/CT is highly specific for prediction of lymph node metastases, but the sensitivity for detection of metastases smaller than 3 mm is limited. Based on our results, [18F]PSMA-1007 PET/CT cannot completely replace ePLND.Patient summaryThis study investigated the use of an imaging method based on a prostate antigen-specific radiopharmaceutical tracer to detect lymph node prostate cancer metastasis. We found that it is unreliable to discover small metastasis.

Novel carbon nanotube-composite for electromagnetic shielding of radiation detectors: A step toward fully integrated positron emission tomography and magnetic resonance imaging systems

Carbon nanotubes (CNT) have shown promising properties, as a filler, for increasing the electrical conductivity of composites entering in the fabrication of high-frequency shielding materials. However, up to now, their features at low-frequency range have received little attention. In this study, composite layers based on pristine CNT and polydimethylsiloxane (PDMS) have been synthesized. Both multi-wall and single-wall CNTs were investigated to determine the specific electrical properties of the composite for eliminating the impact of low-frequency electromagnetic interferences in positron emission tomography/magnetic resonance imaging (PET/MRI) scanners. The CNT dispersibility was studied in various solvents. To fabricate a homogeneous composite, a hybrid method based on ultra-sonication and shear mixing of CNT mixtures was developed. The impedance measurements on thin layers confirmed that a well-processed composite provides the required conductivity (>103 S/cm) for electromagnetic interference shielding in the desired frequency range. Such composite layers achieved a shielding effectiveness of >68 dB in the MRI gradient range (10–100 kHz), and exceeded 80 dB in the MRI RF range (50–500 MHz). The results demonstrated that using these CNT-composite shielding layers, the artifacts due to the electromagnetic interferences of gradient and RF coils in the MRI environment can be avoided for PET imaging.

Integrated Positron Emission Tomography/Magnetic Resonance Imaging for Resting-State Functional and Metabolic Imaging in Human Brain: What Is Correlated and What Is Impacted.

Integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) could simultaneously obtain both functional MRI (fMRI) and 18F-fluorodeoxyglucose (FDG) PET and thus provide multiparametric information for the analysis of brain metabolism. In this study, we aimed to, for the first time, investigate the interplay of simultaneous fMRI and FDG PET scan using a randomized self-control protocol. In total, 24 healthy volunteers underwent PET/MRI scan for 30–40 min after the injection of FDG. A 22-min brain scan was separated into MRI-off mode (without fMRI pulsing) and MRI-on mode (with fMRI pulsing), with each one lasting for 11 min. We calculated the voxel-wise fMRI metrics (regional homogeneity, amplitude of low-frequency fluctuations, fractional amplitude of low-frequency fluctuations, and degree centrality), resting networks, relative standardized uptake value ratios (SUVr), SUVr slope, and regional cerebral metabolic rate of glucose (rCMRGlu) maps. Paired two-sample t-tests were applied to assess the statistical differences between SUVr, SUVr slope, correlation coefficients of fMRI metrics, and rCMRGlu between MRI-off and MRI-on modes, respectively. The voxel-wise whole-brain SUVr revealed no statistical difference (P > 0.05), while the SUVr slope was significantly elevated in sensorimotor, dorsal attention, ventral attention, control, default, and auditory networks (P < 0.05) during fMRI scan. The task-based group independent-component analysis revealed that the most active network components derived from the combined MRI-off and MRI-on static PET images were frontal pole, superior frontal gyrus, middle temporal gyrus, and occipital pole. High correlation coefficients were found among fMRI metrics with rCMRGlu in both MRI-off and MRI-on mode (P < 0.05). Our results systematically evaluated the impact of simultaneous fMRI scan on the quantification of human brain metabolism from an integrated PET/MRI system.

PET parametric imaging based on MR frequency-domain texture information

An integrated positron emission tomography (PET)/magnetic resonance (MR) system combines the unique advantages of the two separate systems to achieve dual modality imaging in the same spatiotemporal region. With this advantage, PET parametric imaging guided by coregistered MRI can effectively improve the spatial resolution of an image. The existing guided imaging methods generally use only the neighborhood intensity information of MR and ignore the texture features in images, but these features can be used as a priori information. Therefore, we propose a novel method of MR-guided kernel reconstruction in this paper. First, a new kernel matrix is constructed by using Gabor texture and voxel intensity information from MR, including diverse image information in the frequency and spatial domains. Then, a new kernel matrix is applied for iterative parametric imaging to obtain improved images. Simulation experiments with PET/MR digital phantom and clinical patient images demonstrate that the additional a priori texture features extracted from the images can further improve the quality of parametric imaging. Compared with the maximum likelihood expectation maximum (MLEM) algorithm and the original kernel algorithm, the proposed method effectively improves tumor recovery and noise reduction in parametric imaging.

Novel Carbon Nanotube-Composite for Electromagnetic Shielding of Radiation Detectors: A Step Toward Fully Integrated Positron Emission Tomography and Magnetic Resonance Imaging Systems

Novel Carbon Nanotube-Composite for Electromagnetic Shielding of Radiation Detectors: A Step Toward Fully Integrated Positron Emission Tomography and Magnetic Resonance Imaging Systems

Comparison of Image Quality According to Phantom Fluid Material in MR-based Attenuation Correction PET Imaging in PET/MR

Integrated positron emission tomography (PET)/magnetic resonance (MR) imaging is gradually being used to improve the rate of cancer lesion detection in the medical field. To enhance the quality of PET/MR images, attenuation correction (AC) techniques are used by applying MR pulse sequences of the controlled aliasing in parallel imaging results in higher acceleration (CAIPI; MR ACSUBDixon-Caipi/SUB) and the generation autocalibrating partially parallel acquisition (GRAPPA; MR ACSUBDixon-Grappa/SUB), based on the T1-weighted two-point Dixon pulse sequence. In addition, quality control using a Jaszczak phantom filled with water and radioisotopes is frequently performed when scanning the patient. When acquiring MR-based AC PET images in the phantom study, artifacts are caused by high permittivity in water, and there is a limitation in the acquisition of uniform image quality. Therefore, the purpose of this study was to compare the image quality using phantom fluids with lower permittivity than water (sodium chloride (NaCl) NaCl+nickel sulfate (NiSO₄)) according to MR ACSUBDixon-Caipi/SUB and MR ACSUBDixon-Grappa/SUB pulse sequences using various quantitative analysis parameters: percent of non-uniformity (PNU), percent contrast recovery (PCR), signal to noise ratio (SNR), and coefficient of variation (COV). The results indicated that the image quality with NaCl+NiSO₄ fluid based on the results was 1.2-, 1.6-, 1.4-, and 1.1 times superior to that of NaCl fluid, respectively. In conclusion, NaCl+NiSO₄ fluid is suitable as a phantom fluid material in PET/MR images.

Can High b Value Diffusion Be a Surrogate Marker for PET-A MR/PET Study in Neurooncology Set Up.

Purpose: Hybrid whole-body magnetic resonance/positron emission tomography (MR/PET) systems are new diagnostic tools enabling the simultaneous acquisition of morphologic and multiparametric functional data, which allow for a diversified characterization of oncological diseases. This study aimed to compare the diagnostic ability of MRI with the diffusion-weighted image (DWI), and simultaneous integrated positron emission tomography MR/PET to detect malignant lesions and elucidate the utility and limitations of these imaging modalities in preoperative and postoperative follow up in cancer patients.Material and Methods: A total of 45 patients undergoing simultaneous MR/PET for CNS ICSOL in our institution between January 2016 and July 2020 were considered in this study. Post-processing was done in Siemens syngo software to generate a b2000 image. This image was then inverted to grayscale and compared with the NAC image of PET.Results: The lesion-based sensitivity, specificity, positive predictive value, and negative predictive value for DWI were 92.3, 83.3, 97.3, and 62.5%, respectively (at 95% CI and p was 0.000). The lesion-based sensitivity, specificity, positive predictive value, and negative predictive value for PET were 97.4, 71.4, 94.9, and 83.3%, respectively (at 95% CI and p was 0.000). The lesion-based sensitivity and specificity of DWI were comparable with those of PET.Conclusions: Although DWI and FDG-PET reflect different tissue properties, there is an association between the measures of both methods in CNS tumors probably because of the coupling of cellularity with tumor metabolism as seen on FDG and other PET tracers. Our study shows that DWI acts as a surrogate biomarker for FDG PET and other tracers in tumors. The method of DWI image generation is simple, radiation-free, and cost-effective in a clinical setup. The simultaneous DWI-PET study provides evidence and confirms the role of DWI in surveillance imaging of tumors.

Radiobiological risks in terms of effective dose and organ dose from 18F-FDG whole-body PET/CT procedures.

IntroductionIntegrated Positron Emission Tomography (PET) with Computerized tomography (CT) (PET/CT) are widely used to diagnose, stage and track human diseases during whole body scanning. Multi-modality imaging is an interesting area of research that aims at acquiring united morphological-functional image information for accurate diagnosing and staging of the disease. However, PET/CT procedure accompanied with high radiation dose from CT and administered radioactivity. The aim of the present study was to estimate the patients’ dose from 18F-fluorodeoxyglucose imaging (18F-FDG) hybrid PET/CT whole body scan.Materials and methodsRADAR (Radiation Dose Assessment Resource) software was used to estimate the effective dose for 156 patients (110 (70.5%)) males and 46 (39.5%) female) examined using Discovery PET/CT 710, GE Medical Systems installed at Kuwait Cancer Control Center (KCCC).ResultsThe effective dose results presented in this PET/CT study ranged from (1.56–9.94 mSv). The effective dose was calculated to be 3.88 mSv in females and 3.71 mSv in males. The overall breast (female), lung, liver, kidney and thyroid were 7.4, 7.2, 5.2, 4, 3 and 2.9, respectively.For females, the body mass index (BMI) was 28.49 kg/m2 and for males it was 26.50 kg/m2 which showed overweight values for both genders. Conclusions: The findings indicate that the effective dose of 18F-FDG in both male and female patients was not substantially different. The study suggested that the risk–benefit proportions of any 18F-FDG whole body PET/CT scan should be clarified and carefully weighed. Patient’s doses are lower compared with previous studies.