Positron Emission Tomography With Computed Tomography Research Articles

The Application of Radiomics and AI to Molecular Imaging for Prostate Cancer.

Molecular imaging is a key tool in the diagnosis and treatment of prostate cancer (PCa). Magnetic Resonance (MR) plays a major role in this respect with nuclear medicine imaging, particularly, Prostate-Specific Membrane Antigen-based, (PSMA-based) positron emission tomography with computed tomography (PET/CT) also playing a major role of rapidly increasing importance. Another key technology finding growing application across medicine and specifically in molecular imaging is the use of machine learning (ML) and artificial intelligence (AI). Several authoritative reviews are available of the role of MR-based molecular imaging with a sparsity of reviews of the role of PET/CT. This review will focus on the use of AI for molecular imaging for PCa. It will aim to achieve two goals: firstly, to give the reader an introduction to the AI technologies available, and secondly, to provide an overview of AI applied to PET/CT in PCa. The clinical applications include diagnosis, staging, target volume definition for treatment planning, outcome prediction and outcome monitoring. ML and AL techniques discussed include radiomics, convolutional neural networks (CNN), generative adversarial networks (GAN) and training methods: supervised, unsupervised and semi-supervised learning.

MRI morphological characteristics of lymph nodes in anal squamous cell carcinoma

ObjectivesPre-treatment staging of anal squamous cell carcinoma (ASCC) includes pelvic MRI and [18F]-fluorodeoxyglucose positron emission tomography with computed tomography (PET-CT). MRI criteria to define lymph node metastases (LNMs) in ASCC are currently lacking. The aim of this study was to describe the morphological characteristics of lymph nodes (LNs) on MRI in ASCC patients with PET-CT-positive LNs.MethodsASCC patients treated at Skåne University Hospital between 2009 and 2017 were eligible for inclusion if at least one positive LN according to PET-CT and a pre-treatment MRI were present. All PET-CT-positive LNs and PET-CT-negative LNs were retrospectively identified on baseline MRI. Each LN was independently classified according to pre-determined morphological characteristics by two radiologists blinded to clinical patient information.ResultsSixty-seven ASCC patients were included, with a total of 181 PET-CT-positive LNs identified on baseline MRI with a median short-axis diameter of 9.0 mm (range 7.5–12 mm). MRI morphological characteristics of PET-CT-positive LNs included regular contour (87%), round shape (89%), and homogeneous signal intensity on T2-weighed images (67%). An additional 78 PET-CT-negative LNs were identified on MRI. These 78 LNs had a median size of 6.8 mm (range 5.5–8.0 mm). The majority of PET-CT-negative LNs had a regular contour, round shape, and a homogeneous signal that was congruent to the primary tumor.ConclusionsThere are MRI-specific morphological characteristics for pelvic LNs in ASCC. PET-CT-positive and negative LNs share similar morphological features apart from size, with PET-CT-positive LNs being significantly larger. Further studies are needed to determine discrimination criteria for LNM in ASCC.

Global molecular calcium score: is there a link between sodium fluoride uptake and cardiovascular risk burden?

Abstract Background Sodium fluoride (18F-NaF) uptake in positron emission tomography with computed tomography (PET-CT) identifies active microcalcification both in atherosclerotic plaques and the aortic valve. Purpose We aimed to evaluate global cardiac microcalcification activity with 18F-NaF, as a measure of the microcalcification burden, in high cardiovascular (CV) risk patients. Additionally, as an exploratory endpoint, we evaluated the association between global cardiac microcalcification and diastolic dysfunction. Methods High CV-risk individuals without previous CV events from a single centre were prospectively scanned with 18F-NaF PET-CT. Total cardiac 18F-NaF uptake was measured as global molecular calcium score (GMCS), which was calculated by summing the product of mean standardized uptake value and volume of the region of interest on every slice within the borders of the heart. The result was then divided by the number of slices to adjust for the volume. Results We included sixty-five patients with a mean age of 64.0 ± 9.0 years and 38.5% females. There was a high rate of CV risk factors, including hypertension (95.4%), diabetes (84.6%), dyslipidemia (78.5%), obesity (58.5%), smoking (26.2%) chronic kidney disease (18.5%), and family history of premature coronary disease (9.2%). The mean 10-year risk of fatal and nonfatal cardiovascular events predicted by ASCVD risk score was 30.54 ± 18.4. Median GMCS was 221.42 [IQR 144.55-317.58]. Individuals with > 5 CV risk factors (46.2%) had increased overall GMCS compared to those with a lower number of CV risk factors (295.29, IQR 159.37-356.87 vs 186.16, IQR 122.57-281.78; p=0.03). Thirty-three patients underwent diastolic dysfunction evaluation by echocardiography. All patients had normal left ventricle ejection fraction, mean of 62.86 ± 3.58%. Mean E/A was 0.88 ± 0.27, mean septal e’ velocity 0.07 ± 0.02 m/s, mean lateral e’ velocity 0.08 ± 0.02 m/s, and mean average E/e’ 10.7 ± 3.3. The mean peak tricuspid regurgitation velocity was 2.14 ± 0.59 m/s and the median indexed left atrium volume was 37, IQR 29-44mL/m2. After applying the algorithm for diagnosis of diastolic dysfunction in subjects with normal ejection fraction, 21.2% had diastolic dysfunction and 36.4% had a normal diastolic function, while 42.4% were indeterminate. There was no correlation between echocardiographic variables of diastolic function and GMCS, except for indexed left atrium volume (r = 0.83, p<0.01). There was no association between GMCS and diastolic function categories. Conclusions In a high CV risk cohort, the global cardiac microcalcification assessed by GMCS was associated with the burden of CV risk factors. Additionally, despite a strong positive correlation between GMCS and indexed left atrium volume, we found no association between GMCS and echocardiographic variables of diastolic function.

Integrating [18F]-Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography with Radiation Therapy and Immunomodulation in Precision Therapy for Solid Tumors.

[18F]-FDG positron emission tomography with computed tomography (PET/CT) imaging is widely used to enhance the quality of care in patients diagnosed with cancer. Furthermore, it holds the potential to offer insight into the synergic effect of combining radiation therapy (RT) with immuno-oncological (IO) agents. This is achieved by evaluating treatment responses both at the RT and distant tumor sites, thereby encompassing the phenomenon known as the abscopal effect. In this context, PET/CT can play an important role in establishing timelines for RT/IO administration and monitoring responses, including novel patterns such as hyperprogression, oligoprogression, and pseudoprogression, as well as immune-related adverse events. In this commentary, we explore the incremental value of PET/CT to enhance the combination of RT with IO in precision therapy for solid tumors, by offering supplementary insights to recently released joint guidelines.

PET/CT scan improves detection of metastatic disease compared with CT scan alone in women with high-grade neuroendocrine cervical cancer: a NeCTuR study

ObjectiveTo determine the optimal imaging modality for women with high-grade neuroendocrine carcinoma of the cervix.MethodsWomen with high-grade neuroendocrine carcinoma of the cervix who had undergone a computed tomography (CT) scan...

Reducing chemotherapy dose intensity by 25% and adding rituximab improves survival in pediatric mature B-cell non-Hodgkin lymphoma in LMIC setting.

Pediatric B-cell non-Hodgkin lymphomas (NHL) in low- and middle-income countries (LMICs) have historically had inferior outcomes due to higher treatment-related mortality (TRM) and relapses. To address this issue, we evaluated the impact of reducing chemotherapy dose intensity by 25% and adding rituximab on outcomes in pediatric B-NHL. Patients, less than 18years of age with group B and C disease as per the Lymphome Malin de Burkitt (LMB) risk stratification were enrolled between September 2017 and October 2022. The LMB-89 protocol, with a 25% reduction in all chemotherapy doses and the addition of rituximab, was administered. The response was assessed using positron emission tomography with computed tomography (PET/CT) after four cycles of chemotherapy (interim) and at the end of treatment. The study included 25 patients with a median age of 6.9years, among whom 20 (80%) were males. Twenty patients had group B and five had group C disease. Complete metabolic response (CMR) was achieved by 22/25 (88%) patients, and three (12%) achieved partial metabolic response (PMR) in the interim PET/CT. At the end of treatment, 22/24 (92%) patients achieved CMR, one had PMR, and one had progressive disease. The median follow-up was 45months (range: 3-71months). The 4-year event-free survival and overall survival were 88% and 92%, respectively. There were two deaths, one due to disease progression and the other due to sepsis. Our study demonstrates a significant improvement in outcomes in pediatric B-NHL compared to previous reports from LMICs, achieved through a 25% reduction in chemotherapy dose intensity and the addition of rituximab.

Association Between 18F-Fluorodeoxyglucose Uptake and Mutation Status of Epidermal Growth Factor Receptor in Sinonasal Tract Cancer.

The Warburg effect of cancer has been applied to detect various carcinomas though the 18F-fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography with computed tomography (PET/CT). 18F-FDG-PET/CT in lung cancer predicted the mutation status of epidermoid growth factor receptor (EGFR). This study aimed to investigate whether 18F-FDG uptake parameters were significantly related to EGFR mutation status in patients with sinonasal tract squamous cell carcinoma (STSCC). Twenty-nine tumor specimens of primary STSCC from patients with definitive treatment were collected. The 18F-FDG uptake from primary tumors was not different between mutant- and wild-status of EGFR on either Mann-Whitney U-test or the receiver operating curve. A metabolic tumor volume of ≥25 with the minimum p-value from the log-rank test for STSCC-specific survival was associated with a significantly shorter STSCC-specific, disease-free, local recurrence-free survival on the univariate and multivariate analyses adjusted for the clinical stage, treatment, and EGFR status. 18F-FDG-PET/CT did not predict mutation of the EGFR status in STSCC.

A comparative study of establishing rabbit vertebral tumor model by two ways of CT-guided percutaneous puncture

ObjectiveTo investigate the difference of tumor formation rate of rabbit vertebral tumor model established by percutaneous injection of V×2 tumor tissue suspension and tumor mass under computed tomography (CT) guidance, and the imaging findings of CT, magnetic resonance images (MRI) and positron emission tomography with computed tomography (PET/CT) at 7 days, 14 days and 21 days after implantation, and preliminarily verify the safety and feasibility of microwave ablation (MWA), percutaneous vertebroplasty (PVP) and microwave ablation combined with percutaneous vertebroplasty (MWA + PVP) in rabbit VX2 vertebral tumor model. MethodsThirty healthy New Zealand rabbits were randomly allocated to tissue suspension group and tumor block group, with 15 rabbits for each group. The VX2 tumor block and mixed suspension were inoculated into the L5 vertebral body under CT-guided percutaneous puncture. The PET/CT, MRI and CT examinations were performed at 7, 14 and 21 days after implantation. Fisher exact probability test was used to compare the success rate of the two implantation methods and the tumor display rate at each time point of the three examination methods. Observe the paralysis of tumor-forming rabbits, and immediately perform MWA/PVP/MWA + PVP treatment according to groups after paralysis to verify the safety and feasibility of treatment. ResultsA total of 18 experimental rabbits were successfully modeled in two groups, of which the success rate was 26.6% (4/15) in tissue suspension group and 93.3% (14/15) in tumor block group, with statistically significant differences between two groups (P < 0.01). The tumor display rates by PET/CT, MRI and CT at each time point after implantation were: 83.3% (15/18), 16.6% (3/18), and 0% (0/18) at 7 days after implantation; 100% (18/18), 88.8% (16/18), and 11.1% (2/18) at 14 days after implantation; and 100% (18/18), 100% (18/18), 77.7% (14/18) at 21 days after implantation. The average paralysis time of 18 experimental rabbits successfully modeled was 24.44 ± 2.38 days, and MWA/PVP/MWA + PVP treatment was performed in groups immediately after paralysis. Except for 2 rabbits who died due to anesthesia overdose during anesthesia before treatment, the remaining 16 rabbits were successfully treated with MWA/PVP/MWA + PVP, and the technical success rate was 100% (16/16). In MWA group, one experimental rabbit was randomly selected and killed after ablation, and histopathological examination (H and E staining) was performed together with 2 experimental rabbits who died of anesthesia. The pathological changes before and after ablation were compared. The survival time of the remaining 15 experimental rabbits varied from 3 to 8 days after treatment. ConclusionThe success rate of establishing rabbit vertebral tumor model by injecting tumor masses under the CT-guided percutaneous puncture is high, and the following MWA and PVP treatment can be successfully conducted. PET/CT is the most sensitive method for early detection of tumor compared with MRI and CT. Spectral Presaturation with Inversion Recovery (SPIR) sequence can significantly improve the detection rate of smaller tumors by MRI and shorten the detection time.

The Role of MRI and PET/CT in Radiotherapy Target Volume Determination in Gastrointestinal Cancers-Review of the Literature.

Positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (MRI) could improve accuracy in target volume determination for gastrointestinal cancers. A systematic search of the PubMed database was performed, focusing on studies published within the last 20 years. Articles were considered eligible for the review if they included patients with anal canal, esophageal, rectal or pancreatic cancer, as well as PET/CT or MRI for radiotherapy treatment planning, and if they reported interobserver variability or changes in treatment planning volume due to different imaging modalities or correlation between the imaging modality and histopathologic specimen. The search of the literature retrieved 1396 articles. We retrieved six articles from an additional search of the reference lists of related articles. Forty-one studies were included in the final review. PET/CT seems indispensable for target volume determination of pathological lymph nodes in esophageal and anal canal cancer. MRI seems appropriate for the delineation of primary tumors in the pelvis as rectal and anal canal cancer. Delineation of the target volumes for radiotherapy of pancreatic cancer remains challenging, and additional studies are needed.

Post-operative PET/CT improves the detection of early recurrence of squamous cell carcinomas of the oral cavity

BackgroundWe evaluate the impact of post-operative 18-fluorodeoxyglucose positron emission tomography with computed tomography (PET/CT) for radiation planning on the detection of early recurrence (ER) and treatment outcomes in oral squamous cell carcinoma (OSCC). MethodsWe retrospectively reviewed the records of patients treated with post-operative radiation between 2005 and 2019 for OSCC at our institution. Extracapsular extension and positive surgical margins were classified as high risk features; pT3-4, node positivity, lymphovascular invasion, perineural invasion, tumor thickness >5 mm, and close surgical margins were considered intermediate risk features. Patients with ER were identified. Inverse probability of treatment weighting (IPTW) was used to adjust for imbalances between baseline characteristics. Results391 patients with OSCC were treated with post-operative radiation. 237 (60.6%) patients underwent post-operative PET/CT planning vs. 154 (39.4%) who were planned with CT only. Patients screened with post-operative PET/CT were more likely to be diagnosed with ER than those planned with CT only (16.5 vs. 3.3%, p < 0.0001). Among patients with ER, those with intermediate features were more likely than those high risk features to undergo major treatment intensification, including re-operation, the addition of chemotherapy, or intensification of radiation by ≥ 10 Gy (91% vs. 9%, p < 0.0001). Post-operative PET/CT was associated with improved disease-free and overall survival for patients with intermediate risk features (IPTW log-rank p = 0.026 and p = 0.047, respectively) but not high risk features (IPTW log-rank p = 0.44 and p = 0.96). ConclusionsUse of post-operative PET/CT is associated with increased detection of early recurrence. Among patients with intermediate risk features, this may translate to improved disease-free survival.

A Comparative Evaluation of Mediastinal Nodal SUVmax and Derived Ratios from 18F-FDG PET/CT Imaging to Predict Nodal Metastases in Non-Small Cell Lung Cancer.

18F-FDG positron emission tomography with computed tomography (PET/CT) is a standard imaging modality for the nodal staging of non-small cell lung cancer (NSCLC). To improve the accuracy of pre-operative staging, we compare the staging accuracy of mediastinal lymph node (LN) standard uptake values (SUV) with four derived SUV ratios based on the SUV values of primary tumours (TR), the mediastinal blood pool (MR), liver (LR), and nodal size (SR). In 2015-2017, 53 patients (29 women and 24 men, mean age 67.4 years, range 53-87) receiving surgical resection have pre-operative evidence of mediastinal nodal involvement (cN2). Among these, 114 mediastinal nodes are resected and available for correlative PET/CT analysis. cN2 status accuracy is low, with only 32.5% of the cN2 cases confirmed pathologically. Using receiver operating characteristic (ROC) curve analyses, a SUVmax of N2 LN performs well in predicting the presence of N2 disease (AUC, 0.822). Based on the respective selected thresholds for each ROC curve, normalisation of LN SUVmax to that for mediastinum, liver and tumour improved sensitivities of LN SUVmax from 68% to 81.1-89.2% while maintaining acceptable specificity (68-70.1%). In conclusion, normalised SUV ratios (particularly LR) improve current pre-operative staging performance in detecting mediastinal nodal involvement.

Metabolic parameters of [18F]FDG PET-CT before and after radiotherapy may predict survival and recurrence in cervical cancer

Background Cervical cancer is the fourth most common female malignancy. [18F]-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET-CT) is routinely performed in patients with locally advanced cervical cancer for staging and treatment response evaluation. With this retrospective, observational cohort study, we wanted to investigate the prognostic value of the maximum standardised uptake value (SUVmax) and the volumetric parameters of metabolic tumour volume (MTV) and total lesion glycolysis (TLG) before and after treatment in women with cervical cancer, with overall survival (OS) and recurrence as outcome measures. Methods Women with cervical cancer referred for curative radiotherapy and who underwent two PET-CT scans (before treatment and approximately 7 months post-treatment) were included. SUVmax, MTV and TLG were measured at baseline and post-treatment on the primary tumour, pelvic and distant lymph node metastases, distant organ metastases, and on total tumour burden. The PET parameters were associated with OS by Cox regression and recurrence by multivariable logistic regression. Kaplan-Meier curves and C-index were used to visualise the prognostic potential of the different measures. Results A total of 133 patients were included. At the primary tumour level and on total tumour burden, age- and clinical-stage adjusted analyses showed a significant association between PET parameters and OS and recurrence when measured post-treatment. At baseline (pre-treatment), MTV and TLG were associated with OS and recurrence, whereas SUVmax was not. C-index from adjusted Cox models on total tumour burden showed higher values for the post-treatment PET compared to baseline. Kaplan-Meier curves demonstrated a greater prognostic potential for MTV and TLG compared to SUVmax, both at baseline and post-treatment. Conclusions The FDG PET-CT-derived parameters SUVmax, MTV, and TLG measured post-treatment can predict OS and recurrence in cervical cancer. Parameters measured before treatment had overall lower prognostic potential, and only MTV and TLG showed significant association to OS and recurrence.

Incidental Diagnosis of Prostate Cancer by 18F-FDG PET-CT Imaging in a Patient During Post-operative Evaluation for Cecal Cancer

Incidental high fluorine-18 FDG (fluorodeoxyglucose) uptake in well-differentiated prostate cancer is rare. We reported the case of a 75-year-old man who underwent a whole-body FDG PET-CT (positron emission tomography with computed tomography) scan for post-operative evaluation of caecal cancer and demonstrated no evidence of recurrence. However, a focal hypermetabolic lesion was detected in the right lateral lobe of the prostate. The patient’s prostatic biopsy from the right lobe revealed well-differentiated adenocarcinoma with a Gleason score of six and a raised serum PSA level. Incidental, focally intense FDG uptake in the prostate gland should be considered for further investigations to confirm the presence of prostate cancer. Bangladesh J. Nuclear Med. 26(1): 51-53, 2023

Evaluation of Pendrin Expression Using Nuclear Imaging Modalities and Immunohistochemistry in Animal Thyroid Cancer Model.

The impaired ability of thyroid cancer (TC) cells to uptake and concentrate iodine represents a major therapeutic challenge in malignant TC management. This has been reported probably due to reduced or loss of expression of pendrin in thyroid tumors. In view of this, we evaluated the pendrin expression in the chemically induced (using N-bis[2-hydroxypropyl] nitrosamine [DHPN]) TC model in Wistar rats. Uptake in the thyroid gland was evaluated by positron emission tomography with computed tomography (PET-CT) and scintigraphy imaging. Further histopathology (HP) and immunohistochemistry (IHC) were performed for confirming malignancy. The altered uptake in the thyroid gland was observed by PET-CT and scintigraphy imaging. Significant pathological changes in the thyroid were observed using 2-deoxy-2-(fluorine-18) fluoro-D-glucose PET-CT, technetium-99m pertechnetate imaging, and reduced iodine-131 uptake (n = 4) in DHPN-induced animals compared to control indicative of thyroid cell proliferation. In treated groups, tissue HP revealed hyperplastic follicular to papillary cell proliferation with variable mitotic activity. The malignant nature of the tissue and variable uptake of the tracer were further reconfirmed by IHC. IHC revealed reduced pendrin expression in malignant thyroid tissue. Hence, nuclear imaging techniques can be of aid in the early identification and evaluation of cellular changes during the early development of tumor models in laboratory animals. In conclusion, our study reveals that pendrin expression plays a vital role in thyroid uptake, and its reduction was observed in TC in a chemically induced TC model.

Prognostic Value of Month 1 Bone Marrow and PET MRD Status in CAR-T Therapy for Myeloma

Background: Minimal residual disease (MRD) is prognostic for survival in multiple myeloma (MM). MRD is usually assessed in the bone marrow (BM) by flow cytometry or NGS. Guideline is also available for MRD assessment by positron emission tomography with computed tomography (PET/CT) to provide a global representation of the tumor burden beyond osteolytic lesions and evaluate for response to extra-medullary disease (EMD). We examined MRD status in MM patients using a combination of BM and PET/CT MRD during the first-year post CAR-T infusion. Methods: We conducted a retrospective chart review of MM patients infused with different CAR-T products between Apr 2018 and Jun 2022 at Mayo Clinic. All PET/CT scans were assessed as per IMWG criteria. BM MRD was assessed by flow cytometry with a sensitivity of 10-5 (minimum 2x106 events acquired). Patient best response was defined as per IMWG criteria. The Kruskal-Wallis rank sum test was used to determine associations between continuous variable and categories, and Pearson's chi-square test were used to evaluate associations for categorical variables. PFS was analyzed using Kaplan-Meier analysis and statistical significance was assessed using the two-tailed log-rank test. Results: In our cohort of 94 CAR-T recipients, including 40 patients who received FDA-approved CAR-T in standard of care practice, median age was 63 years, 50% (47/94) were males, 40% (38/94) had high risk cytogenetics with median of 5 prior lines of therapy, 16% (15/94) had bone independent EMD and 29% (27/94) had bone associated EMD. Incidence of CRS was 81%, 5% grade ≥ 3 CRS. Incidence of ICANS was 21%, 4% grade ≥ 3 ICANS. CR/sCR rate was 32%. At median follow-up of 12.8 months, median PFS was 10.8 (95% CI: 7.8, 26.4) mo. Eighty-three patients (88%) had evaluable BM at month (mo) 1, 80% (67/83) were BM MRDneg at mo 1. Baseline demographics were comparable between the two groups except age (BM MRDneg;63 years vs BM MRDpos;58 years, p<0.05). Among the MRDneg patients, IMWG response at month 1 was CR/sCR in 42% (27/67), VGPR in 39% (25/67), PR in 15% (10/67), SD in 3% (2/67) and 1% (1/67) patients were not evaluable. 16/26 (62%) had sustained BM MRDneg at month 6 and 9/20 (45%) at month 12. At median follow-up of 14.7 months, median PFS among patients with BM MRDneg at 1 mo was 17.5 (95% CI: 10.8, NA) mo vs 2.9 (95%CI: 1.5, NA) for BM MRDpos (p<0.0001). At month 1, 58 pts had both BM and PET/CT assessments available, 26/58 (45%) were both BM MRDneg/PET MRDneg, 22/58 (38%) were MRDneg for either BM or PET and 10/58 (17%) were positive for both BM and PET (BM MRDpos/PET MRDpos). Baseline demographics except age were comparable between the 2 groups (Table 1). Rate of sustained BM MRDneg/PET MRDneg was 33% (6/18) at 6 mo and 44% (7/16) at 12 mo post CAR-T. Two patients who were BM MRDneg/PET MRDpos at mo 1 had eventual radiologic conversion to PET MRDneg at mo 3 and 12 (2/58, 3.4%). The median PFS for BM MRDneg/ PET MRDneg was significantly longer as compared to others (p<0.001, Figure 1). Conclusion: MRD status at month 1 is prognostic for prolonged PFS. The rate of dual BM/PET MRDneg rate is lower than BM MRD alone. The PFS is longer for patients with dual MRDneg for BM and PET. These results highlight the need for additional interventions among patients with evidence of residual disease early after CART infusion. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Comparing Radiation Dose Between Contrast-Enhanced and Non-Contrast-Enhanced CTAC Acquisition in 18F-FDG-PET/CT Examination

Introduction: Hybrid Positron Emission Tomography with Computed Tomography (PET/CT) imaging is well established in the oncology setting. However, in the current cancer diagnostic imaging approach in Malaysia patients need separate CT and PET/CT examinations for morphologic and physiologic cancer staging, respectively, as PET/CT is unable to produce images with optimum diagnostic quality. Therefore, introducing contrast media into CT attenuation correction (CTAC) acquisition to increase image quality have raised concerns on heightened radiation exposure. This study aimed to verify the amount of external radiation exposure irradiated to the patient converging to the scanning protocol implemented in whole-body (WB) 18F-FDG-PET/CT examination. Methods: A retrospective study was conducted to determine the radiation dose delivered during CTAC acquisition of 18F-FDG-PET/CT examination at three hospitals providing PET/CT imaging services in Penang State. The implemented scanning protocols and parameters, and the effective dose received by the patient were analysed based on dose length product (DLP) and CTDIvol reported by the scanner. Results: CTAC of WB 18F-FDG-PET/CT imaging was executed as either non-contrast (NC-CTAC) or contrast-enhanced (CE-CTAC). CE-CTAC produced a 250% higher radiation dose compared to NC-CTAC. The scanning parameter differences that significantly contributed to increased radiation dose were the tube current and pitch value. Conclusion: CE-CTAC delivered a higher radiation dose than NC-CTAC acquisition in WB 18F-FDG PET/CT imaging due to different mAs and pitch as scanning parameters. Malaysian Journal of Medicine and Health Sciences (2022) 18(SUPP15): 132-139. doi:10.478

Behandlung von Staphylococcus-aureus-Blutstrominfektionen

Staphylococcus aureus bloodstream infections (SAB) represent a distinct clinical entity. Due to the frequency and the associated high morbidity and mortality, special requirements apply to the clinical management. Thus, in contrast to coagulase-negative staphylococci, even the detection of S. aureus in a single blood culture bottle is considered to be an infection requiring treatment. A classification into complicated versus uncomplicated bloodstream infections is carried out, with implications for the recommended duration of treatment (2 vs. 4–6 weeks). The use of transesophageal echocardiography to exclude endocarditis is indicated in the vast majority of cases. Because of frequent clinically silent septic metastases, positron emission tomography with computed tomography (PET-CT) is a useful tool for detection of nidi. For methicillin-sensitive S. aureus (MSSA), flucloxacillin and cefazolin are applied as basic treatment and for methicillin-resistant S. aureus (MRSA), vancomycin or daptomycin are used depending on the focus and comorbidity. If foreign material is present, a combination of basic treatment with rifampicin or fosfomycin should be considered. Source control by abscess drainage or removal of infected intravascular catheters, intracardiac devices or if necessary artificial joints is important. Studies show that infectious disease consultations improve the quality of care and mortality in SAB. Current open questions address the identification of subpopulations that benefit from combination treatment, the effectiveness and timing of stepdown oral antibiotic treatment, and a possible reduction in the overall duration of treatment. This review article summarizes the current standards for diagnostics and treatment of patients with SAB and presents recent relevant studies on this condition.

Skeletal scintigraphy as an important complement for detecting bone metastasis from nasopharyngeal carcinoma

Bone metastasis occurs frequently in patients with nasopharyngeal carcinoma (NPC). Although fluorine-18 fluorodeoxyglucose positron emission tomography with computed tomography (PET/CT) has been proven to be more sensitive at detecting bone metastases than Technetium-99m methylene diphosphonate skeletal scintigraphy in pretreatment patients with NPC in most clinical settings, there have been metastatic lesions that were positive on skeletal scintigraphy but negative on PET/CT scans. Herein, we report the case of a patient with stage IV NPC that manifested as multiple metabolically abnormal lesions on pretreatment skeletal scintigraphy and were considered malignant although they were negative on PET/CT examination. Follow-up evaluations with both skeletal scintigraphy and PET/CT scans as post-therapeutic imaging are also presented.

Cardiac microcalcification burden: Global assessment in high cardiovascular risk subjects with Na[18F]F PET-CT

BackgroundFluorine-18 sodium fluoride (Na[18F]F) atherosclerotic plaque uptake in positron emission tomography with computed tomography (PET-CT) identifies active microcalcification. We aim to evaluate global cardiac microcalcification activity with Na[18F]F, as a measure of unstable microcalcification burden, in high cardiovascular (CV) risk patients. Methods and ResultsThirty-four high CV risk individuals without previous CV events were scanned with Na[18F]F PET-CT. Cardiac Na[18F]F uptake was assessed through the global molecular calcium score (GMCS), which was calculated by summing the product of the mean standardized uptake value times the area of the cardiac regions of interest times the slice thickness for all cardiac transaxial slices, divided by the total number of slices. Mean age is 63.5 ± 7.8 years and 62% male. Median GMCS is 320.9 (240.8-402.8). Individuals with more than five CV risk factors (50%) have increased GMCS [356.7 (321.0-409.6) vs. 261.1 (225.6-342.1), P = 0.01], which is positively correlated with predicted fatal CV risk by SCORE (rs = 0.32, P = 0.04). There is a positive correlation between GMCS and weight (rs = 0.61), body mass index (rs = 0.66), abdominal perimeter (rs = 0.74), thoracic fat volume (rs = 0.47), and epicardial adipose tissue (rs = 0.41), all with P ≤ 0.01. There is no correlation between GMCS and coronary calcium score nor coronary artery wall Na[18F]F uptake. ConclusionsIn a high CV risk group, the global cardiac microcalcification burden is related to CV risk factors, metabolic syndrome variables and cardiac fat. Cardiac GMCS is a promising risk stratification tool, combining a straightforward and objective methodology with a comprehensive analysis of both coronary and valvular microcalcification.

The value of FDG PET/CT in the management of malignant melanoma: a retrospective study

Objectives: Positron Emission Tomography with Computed Tomography (PET/CT) is a valuable imaging method for the restaging of malignant diseases as well as the evaluation of treatment outcomes. Malignant melanoma is an aggressive tumor. Surgical resection is the primary treatment. As melanoma lesions are mostly FDG-avid, whole-body 18F-fluorodeoxyglucose (18F-FDG) PET/CT imaging modality can be used to determine the spread of the tumor. In the present study, we intended to share our clinical experience with FDG PET/CT in malignant melanoma patients under different kinds of treatment. Methods: In this retrospective study, the data sets of 122 patients who had surgical resection of known primary tumors, all of which were histopathology-proven malignant melanoma, were analyzed. All patients underwent baseline 18F-FDG PET/CT scan no sooner than 45 days and at least once after surgery. Clinical information, radiological imaging, histopathology, and treatment modalities were noted for all patients, and 18F-FDG PET/CT findings were examined. Results: All patients were histopathology-proven and 47 of them had acral lentiginous, 37 nodular, 23 amelanotic, and 15 atypical malignant melanoma. Local recurrence was detected by 18F-FDG PET/CT in 13 (10.6%; 3 male, 10 female) of the 122 patients, and the mean recurrence time after diagnosis was 3 ± 1.4 years. 10 patients with brain and bone metastases underwent radiotherapy. 19 patients with lung, bone, and hepatic metastases received chemotherapy and 22 patients immunotherapy. Conclusions: Malignant melanoma is a type of skin cancer that may involve any organ. In localized cases, complete surgical resection may be adequate for a cure. If diagnosed with the latter type, the whole body of the patient must be examined.