Performance of whole-body PET/CT for the detection of distant malignancies in various cancers: a systematic review and meta-analysis

Reliability of predicting low-burden (≤ 2) positive axillary lymph nodes indicating sentinel lymph node biopsy in primary operable breast cancer - a retrospective comparative study with PET/CT and breast MRI

BACKGROUND

Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in early breast cancer patients with low-burden axillary metastasis (≤ 2 positive nodes). This study aimed to determine the diagnostic performances of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and breast magnetic resonance imaging in detecting axillary lymph node (ALN) metastases and the reliability to predict ALN burden.

METHODS

A total of 275 patients with primary operable breast cancer receiving preoperative PET/CT and upfront surgery from January 2001 to December 2022 in a single institution were enrolled. A total of 244 (88.7%) of them also received breast MRI. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT and breast MRI were assessed. The predictive values to determine ALN burden were evaluated using radio-histopathological concordance.

RESULTS

PET/CT demonstrated a sensitivity of 53.4%, specificity of 82.1%, PPV of 65.5%, NPV of 73.5%, and accuracy of 70.9% for detecting ALN metastasis, and the corresponding values for MRI were 71.8%, 67.8%, 56%, 80.8%, and 69.2%, respectively. Combining PET/CT and MRI showed a significantly higher PPV than MRI (72.7% vs 56% for MRI alone, p = 0.037) and a significantly higher NPV than PET/CT (84% vs 73.5% for PET/CT alone, p = 0.041). For predicting low-burden axillary metastasis (1-2 positive nodes), the PPVs were 35.9% for PET/CT, 36.7% for MRI, and 55% for combined PET/CT and MRI. Regarding patients with 0-2 positive ALNs in imaging, who were indicated for SLNB, the predictive correctness was 96.1% for combined PET/CT and MRI, 95.7% for MRI alone, and 88.6% for PET/CT alone.

CONCLUSIONS

PET/CT and breast MRI exhibit high predictive values for identifying low-burden axillary metastasis in patients with operable breast cancer with ≦ 2 positive ALNs on imaging.

Multimodal Cardiac Imaging in the Assessment of Patients Who Have Suffered a Cardioembolic Stroke: A Review

Cardioembolic strokes account for 20-25% of all ischaemic strokes, with their incidence increasing with age. Cardiac imaging plays a crucial role in identifying cardioembolic causes of stroke, with early and accurate identification affecting treatment, preventing recurrence, and reducing stroke incidence. Echocardiography serves as the mainstay of cardiac evaluation. Transthoracic echocardiography (TTE) is the first line in the basic evaluation of structural heart disorders, valvular disease, vegetations, and intraventricular thrombus. It can be used to measure chamber size and systolic/diastolic function. Trans-oesophageal echocardiography (TOE) yields better results in identifying potential cardioembolic sources of stroke and should be strongly considered, especially if TTE does not yield adequate results. Cardiac computed tomography and cardiac magnetic resonance imaging provide better soft tissue characterisation, high-grade anatomical information, spatial and temporal visualisation, and image reconstruction in multiple planes, especially with contrast. These techniques are useful in cases of inconclusive echocardiograms and can be used to detect and characterise valvular lesions, thrombi, fibrosis, cardiomyopathies, and aortic plaques. Nuclear imaging is not routinely used, but it can be used to assess left-ventricular perfusion, function, and dimensions and may be useful in cases of infective endocarditis. Its use should be considered on a case-by-case basis. The accuracy of each imaging modality depends on the likely source of cardioembolism, and the choice of imaging approach should be tailored to individual patients.

The Superiority of Fibroblast Activation Protein Inhibitor (FAPI) PET/CT Versus FDG PET/CT in the Diagnosis of Various Malignancies

Cancer represents a major cause of death worldwide and is characterized by the uncontrolled proliferation of abnormal cells that escape immune regulation. It is now understood that cancer-associated fibroblasts (CAFs), which express specific fibroblast activation protein (FAP), are critical participants in tumor development and metastasis. Researchers have developed various FAP-targeted probes for imaging of different tumors from antibodies to boronic acid-based inhibitor molecules and determined that quinoline-based FAP inhibitors (FAPIs) are the most appropriate candidate as the radiopharmaceutical for FAPI PET/CT imaging. When applied clinically, FAPI PET/CT yielded satisfactory results. Over the past few years, the utility and effectiveness of tumor detection and staging of FAPI PET/CT have been compared with FDG PET/CT in various aspects, including standardized uptake values (SUVs), rate of absorbance and clearance. This review summarizes the development and clinical application of FAPI PET/CT, emphasizing the diagnosis and management of various tumor types and the future prospects of FAPI imaging.

Comparison of whole-body 18F-FDG PET/CT and PET/MRI for distant metastases in patients with malignant tumors: a meta-analysis

BACKGROUND

As a first-line imaging modality, whole-body fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) and 18F-FDG PET/magnetic resonance imaging (MRI) had been widely applied in clinical practice. However, 18F-FDG PET/MRI may be superior to PET/CT for the diagnosis of distant metastases in patients with advanced-stage. Therefore, it is timely and important to systematically determine the diagnostic accuracy of 18F-FDG PET/MRI compared with that of 18F-FDG PET/CT for the diagnosis of distant metastases.

METHODS

This study aimed to compare the diagnostic accuracy of 18F-FDG PET/CT and PET/MRI for the diagnosis of distant metastases in patients with malignant tumors. Relevant studies using both 18F-FDG PET/CT and PET/MRI for assessment of distant metastases in patients with malignant tumors were searched in PubMed, Embase, The Cochrane Library, and Scopus from January 2010 to November 2023. Two reviewers independently selected studies according to the inclusion and exclusion criteria. A reviewer extracted relevant data and assessed the quality of the eligible studies. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and area under the summary receiver operating characteristic curve (AUC) for 18F-FDG PET/CT and PET/MRI were analyzed. Subgroup analysis was performed.

RESULTS

Across 14 studies (1042 patients), 18F-FDG PET/MRI had a higher sensitivity (0.87 versus 0.81), AUC value (0.98 versus 0.95), and similar specificity (0.97 versus 0.97), than PET/CT for detecting distant metastases. In 3 studies of breast cancer (182 patients), 18F-FDG PET/MRI had a higher sensitivity (0.95 versus 0.87) and specificity (0.96 versus 0.94) than PET/CT. In 5 studies of lung cancer (429 patients), 18F-FDG PET/CT had a higher sensitivity (0.87 versus 0.84) and a lower specificity (0.95 versus 0.96) to PET/MRI.

CONCLUSIONS

18F-FDG PET/MRI and PET/CT both performed well as detectors of distant metastases in patients with malignant tumors, and the former has higher sensitivity. The subgroup analysis highlights that 18F-FDG PET/MRI and PET/CT hold different advantages for distant metastases staging in different tumors, PET/MRI has a higher accuracy in patients with breast cancer patients, while PET/CT has a higher accuracy in patients with lung cancer.

Obesity and breast cancer

The paper presents an analysis of the latest literature data on the problem of obesity and breast cancer (BC). This review presents modern approaches to the diagnosis of BC in obese patients, new molecular methods of breast imaging,  analyzes the features of the course of BC with obesity depending on menstrual status, molecular biological subtypes of the tumor, the mechanisms of the development of BC against the background of obesity.

Comparison of 68Ga-FAPI and 18F-FDG PET/CT in the Evaluation of Advanced Lung Cancer

Background Gallium 68 (⁶⁸Ga)-labeled fibroblast-activation protein inhibitor (FAPI) has recently been introduced as a promising tumor imaging agent. Purpose To compare ⁶⁸Ga-FAPI PET/CT with fluorine 18 (¹⁸F)-labeled fluorodeoxyglucose (FDG) PET/CT in evaluating lung cancer. Materials and Methods In this prospective study conducted from September 2020 to February 2021, images from participants with lung cancer who underwent both ⁶⁸Ga-FAPI and ¹⁸F-FDG PET/CT examinations were analyzed. The tracer uptakes, quantified by maximum standardized uptake value (SUV_max) and target-to-background ratio (TBR), were compared for paired positive lesions between both modalities using the paired t test or Wilcoxon signed-rank test. Results Thirty-four participants (median age, 64 years [interquartile range: 46-80 years]; 20 men) were evaluated. From visual evaluation, ⁶⁸Ga-FAPI PET/CT and ¹⁸F-FDG PET/CT showed similar performance in the delineation of primary tumors and detection of suspected metastases in the lungs, liver, and adrenal glands. The metabolic tumor volume in primary and recurrent lung tumors showed no difference between modalities (mean: 11.6 vs 10.8, respectively; P = .68). However, compared with ¹⁸F-FDG PET/CT, ⁶⁸Ga-FAPI PET/CT depicted more suspected metastases in lymph nodes (356 vs 320), brain (23 vs 10), bone (109 vs 91), and pleura (66 vs 35). From semiquantitative evaluation, the SUV_max and TBR of primary or recurrent tumors, positive lymph nodes, bone lesions, and pleural lesions at ⁶⁸Ga-FAPI PET/CT were all higher than those at ¹⁸F-FDG PET/CT (all P < .01). Although SUV_max of ⁶⁸Ga-FAPI and ¹⁸F-FDG in brain metastases were not different (mean SUV_max: 9.0 vs 7.4, P = .32), TBR was higher with ⁶⁸Ga-FAPI than with ¹⁸F-FDG (mean: 314.4 vs 1.0, P = .02). Conclusion Gallium 68-labeled fibroblast-activation protein inhibitor PET/CT may outperform fluorine 18-labeled fluorodeoxyglucose PET/CT in staging lung cancer, particularly in the detection of metastasis to the brain, lymph nodes, bone, and pleura. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Jacobson and Van den Abbeele in this issue.

A comparative analysis: international variation in PET-CT service provision in oncology-an International Cancer Benchmarking Partnership study

Objective

To explore differences in position emission tomography-computed tomography (PET-CT) service provision internationally to further understand the impact variation may have upon cancer services. To identify areas of further exploration for researchers and policymakers to optimize PET-CT services and improve the quality of cancer services.

Design

Comparative analysis using data based on pre-defined PET-CT service metrics from PET-CT stakeholders across seven countries. This was further informed via document analysis of clinical indication guidance and expert consensus through round-table discussions of relevant PET-CT stakeholders. Descriptive comparative analyses were produced on use, capacity and indication guidance for PET-CT services between jurisdictions.

Setting

PET-CT services across 21 jurisdictions in seven countries (Australia, Denmark, Canada, Ireland, New Zealand, Norway and the UK).

Participants

None.

Intervention(s)

None.

Main Outcome Measure(s)

None.

Results

PET-CT service provision has grown over the period 2006–2017, but scale of increase in capacity and demand is variable. Clinical indication guidance varied across countries, particularly for small-cell lung cancer staging and the specific acknowledgement of gastric cancer within oesophagogastric cancers. There is limited and inconsistent data capture, coding, accessibility and availability of PET-CT activity across countries studied.

Conclusions

Variation in PET-CT scanner quantity, acquisition over time and guidance upon use exists internationally. There is a lack of routinely captured and accessible PET-CT data across the International Cancer Benchmarking Partnership countries due to inconsistent data definitions, data linkage issues, uncertain coverage of data and lack of specific coding. This is a barrier in improving the quality of PET-CT services globally. There needs to be greater, richer data capture of diagnostic and staging tools to facilitate learning of best practice and optimize cancer services.

Diabetes, Obesity, and Inflammation: Impact on Clinical and Radiographic Features of Breast Cancer

Obesity, diabetes, and inflammation increase the risk of breast cancer, the most common malignancy in women. One of the mainstays of breast cancer treatment and improving outcomes is early detection through imaging-based screening. There may be a role for individualized imaging strategies for patients with certain co-morbidities. Herein, we review the literature regarding the accuracy of conventional imaging modalities in obese and diabetic women, the potential role of anti-inflammatory agents to improve detection, and the novel molecular imaging techniques that may have a role for breast cancer screening in these patients. We demonstrate that with conventional imaging modalities, increased sensitivity often comes with a loss of specificity, resulting in unnecessary biopsies and overtreatment. Obese women have body size limitations that impair image quality, and diabetes increases the risk for dense breast tis-sue. Increased density is known to obscure the diagnosis of cancer on routine screening mammography. Novel molecu-lar imaging agents with targets such as estrogen receptor, human epidermal growth factor receptor 2 (HER2), pyrimi-dine analogues, and ligand-targeted receptor probes, among others, have potential to reduce false positive results. They can also improve detection rates with increased resolution and inform therapeutic decision making. These emerg-ing imaging techniques promise to improve breast cancer diagnosis in obese patients with diabetes who have dense breasts, but more work is needed to validate their clinical application.

Addition of [18 F]Fluorodeoxyglucose Positron Emission Tomography With Computed Tomography to Cross-Sectional Imaging Improves Staging and Alters Management in Hepatocellular Carcinoma

In this work, we characterize the value of positron emission tomography (PET) with computed tomography (CT) in combination with cross-sectional imaging for staging and prognostication of hepatocellular carcinoma (HCC) patients. In this retrospective cohort study, HCC patients underwent PET-CT after initial staging with contrast-enhanced CT or magnetic resonance imaging (MRI). The benefit of PET-CT was measured by the identification of new HCC lesions, and potential harm was quantified by the number of false positives and subsequent diagnostic evaluation. We used multivariate Cox regression analysis to evaluate the association between the highest grade on PET-CT with the risk of extrahepatic metastasis, progression-free, and overall survival. Among 148 patients, PET-CT detected additional extrahepatic metastasis in 11.9% of treatment-naïve and 13.8% of treatment-experienced patients. PET-CT changed the Barcelona Clinic Liver Cancer (BCLC) staging in 5.9% of treatment-naïve and 18.8% of treatment-experienced patients compared with CT/MRI alone, changing HCC management in 9.9% and 21.3% of patients, respectively. Of the patients, 5% (n = 8) experienced severe physical harm requiring additional procedures to evaluate extrahepatic findings. High tumor grade on PET-CT was independently associated with a higher likelihood of extrahepatic metastasis (hazard ratio [HR], 17.1; 95% confidence interval [CI], 3.6-81.5) and worse overall survival (HR, 2.4; 95% CI, 1.4-4.3). Treatment-experienced patients (versus treatment-naïve patients; HR, 9.7; 95% CI, 1.9-49.4) and BCLC stage A (HR, 8.2; 95% CI, 1.5-45.9; P < 0.01) and BCLC stage B (HR, 20.6; 95% CI, 1.5-282.2; P < 0.05) were more likely to have an upstaging with PET-CT compared with BCLC stage C (reference). PET-CT provides prognostic information and improves tumor staging beyond CT/MRI alone, with subsequent changes in management for patients with HCC.

Accuracy of 18 F-FDG PET/CT in Detection of Neck Metastases of Oral Squamous Cell Carcinoma in Patients Without Large Palpable Lymph Nodes

OBJECTIVE

To measure the efficacy of positron emission tomography/computed tomography (PET/CT) in the diagnosis of neck metastases of oral squamous cell carcinoma (OSCC) in patients without enlarged lymph nodes and to determine the threshold of maximum standardized uptake values (SUV_max) in diagnosis.

STUDY DESIGN

In total, 78 OSCC patients without large palpable lymph nodes were included. PET/CT findings were compared with histopathologic neck status.

RESULTS

Neck dissection was performed in 78 patients with 98 neck sides, and 31 neck sides harbored metastases. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 83.9%, 73.1%, 76.5%, 59.1%, and 90.7%, respectively. The area under the curve in receiver operating characteristic analysis was 0.76, which indicated that SUV_max of lymph nodes was useful in diagnosis of pathologic neck status. The threshold SUV_max was 2.21, which was the best diagnosis threshold of neck metastasis.

CONCLUSIONS

PET/CT is valuable in diagnosis of neck status. The probability of neck metastasis increased with increasing SUV_max values, but the threshold SUV_max should not be the sole criterion for determining the presence of neck metastases. Fluorodeoxyglucose PET/CT is recommended for evaluation of neck status in OSCC patients without large palpable lymph nodes.

Role of 18F-FDG PET/CT in establishing new clinical and therapeutic modalities in lung cancer. A short review

Lung cancer is a fairly common malignancy. An early diagnosis and a reliable staging and re-staging with the aim to detect both local and distant relapse are of utmost importance in planning the therapeutic management. The imaging diagnostic work-up of patients with lung cancer usually includes conventional imaging (chest X-ray, contrast-enhanced CT, bone scan) and more recently ¹⁸F-FDG PET/CT. Great advances in the management of lung cancer are based on the information provided by ¹⁸F-FDG PET/CT, as it supplies both metabolic and anatomic information (better localisation). There is vast evidence in the literature demonstrating its utility in (a) characterising benign versus malignant solitary nodules, (b) staging and re-staging lung cancer, (c) guiding the type of therapy, (d) monitoring treatment response and (e) predicting outcome. In particular, given its specificity in differentiating ¹⁸F-FDG-avid relapse from post-surgical changes or post-radiation fibrosis (which do not take up ¹⁸F-FDG), PET/CT can detect recurrent disease after initial treatment and (being a whole-body technique) has demonstrated high accuracy in the detection of distant metastases or secondary tumours. In conclusion, ¹⁸F-FDG PET/CT can be considered a highly accurate and reliable method for staging and re-staging lung cancer, and is highly effective in guiding personalised therapies.

Clinical usefulness of 18F-FDG PET/CT for the detection of distant metastases in patients with non-small cell lung cancer at initial staging: a meta-analysis

Background

We undertook a meta-analysis to evaluate the clinical usefulness of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for the detection of distant metastases in patients with non-small cell lung cancer (NSCLC) at initial staging.

Materials and methods

All topic-related studies were comprehensively searched in the MEDLINE and Embase databases. We obtained the summary estimates and constructed the summary receiver operating characteristic curve for ¹⁸F-FDG PET/CT using the bivariate regression model.

Results

Across 10 studies (1333 patients), the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for ¹⁸F-FDG PET/CT were 0.81 (95% confidence interval [CI] = 0.63–0.92), 0.96 (95% CI = 0.94–0.98), 22.9 (95% CI = 13.3–39.5), and 0.20 (95% CI = 0.09–0.42), respectively. Overall weighted area under the curve was 0.97 (95% CI = 0.96–0.98).

Conclusion

¹⁸F-FDG PET/CT has a good diagnostic performance for distant metastasis staging in patients with NSCLC at initial staging.

Clinical value of fluorine-18 2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography in penile cancer

Purpose

This study investigated the value of Fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging in the management of patients with advanced penile cancer.

Patients and Methods

Between January 2009 and August 2012, 48 patients with penile cancer at our center underwent FDG-PET/CT after CT (n=39) or magnetic resonance imaging (MRI; n=9). The accuracy of FDG-PET/CT was assessed with both organ-based and patient-based analyses. FDG-PET/CT findings were validated by either biopsy or serial CT/MRI. Clinician questionnaires performed before and after FDG-PET/CT evaluated whether the scan results affected management.

Results

One hundred fifteen individual lesions were evaluable in 42 patients for the organ-based analysis. Overall sensitivity was 85% and specificity was 86%. In the patient-based analysis, overall sensitivity and specificity were 82% and 93%, respectively. Pre- and post-PET surveys showed that FDG-PET/CT detected more malignant diseases than CT/MRI in 33% patients. Planned treatments were changed in 57% patients after FDG-PET/CT scan.

Conclusion

FDG-PET/CT has good sensitivity and specificity in the detection of metastatic penile cancer. It provides more diagnostic information to enhance clinical management than CT/MRI.

Risk-stratifying capacity of PET/CT metabolic tumor volume in stage IIIA non-small cell lung cancer

OBJECTIVES

Stage IIIA non-small cell lung cancer (NSCLC) is heterogeneous in tumor burden, and its treatment is variable. Whole-body metabolic tumor volume (MTVWB) has been shown to be an independent prognostic index for overall survival (OS). However, the potential of MTVWB to risk-stratify stage IIIA NSCLC has previously been unknown. If we can identify subgroups within the stage exhibiting significant OS differences using MTVWB, MTVWB may lead to adjustments in patients' risk profile evaluations and may, therefore, influence clinical decision making regarding treatment. We estimated the risk-stratifying capacity of MTVWB in stage IIIA by comparing OS of stratified stage IIIA with stage IIB and IIIB NSCLC.

METHODS

We performed a retrospective review of 330 patients with clinical stage IIB, IIIA, and IIIB NSCLC diagnosed between 2004 and 2014. The patients' clinical TNM stage, initial MTVWB, and long-term survival data were collected. Patients with TNM stage IIIA disease were stratified by MTVWB. The optimal MTVWB cutoff value for stage IIIA patients was calculated using sequential log-rank tests. Univariate and multivariate cox regression analyses and Kaplan-Meier OS analysis with log-rank tests were performed.

RESULTS

The optimal MTVWB cut-point was 29.2 mL for the risk-stratification of stage IIIA. We identified statistically significant differences in OS between stage IIB and IIIA patients (p < 0.01), between IIIA and IIIB patients (p < 0.01), and between the stage IIIA patients with low MTVWB (below 29.2 mL) and the stage IIIA patients with high MTVWB (above 29.2 mL) (p < 0.01). There was no OS difference between the low MTVWB stage IIIA and the cohort of stage IIB patients (p = 0.485), or between the high MTVWB stage IIIA patients and the cohort of stage IIIB patients (p = 0.459). Similar risk-stratification capacity of MTVWB was observed in a large range of cutoff values from 15 to 55 mL in stage IIIA patients.

CONCLUSIONS

Using MTVWB cutoff points ranging from 15 to 55 mL with an optimal value of 29.2 mL, stage IIIA NSCLC may be effectively stratified into subgroups with no significant survival difference from stages IIB or IIIB NSCLC. This may result in more accurate survival estimation and more appropriate risk adapted treatment selection in stage IIIA NSCLC.

Tumor Metabolic Features Identified by 18F-FDG PET Correlate with Gene Networks of Immune Cell Microenvironment in Head and Neck Cancer

The importance of ¹⁸F-FDG PET in imaging head and neck squamous cell carcinoma (HNSCC) has grown in recent decades. Because PET has prognostic values, and provides functional and molecular information in HNSCC, the genetic and biologic backgrounds associated with PET parameters are of great interest. Here, as a systems biology approach, we aimed to investigate gene networks associated with tumor metabolism and their biologic function using RNA sequence and ¹⁸F-FDG PET data. Methods: Using RNA sequence data of HNSCC downloaded from The Cancer Genome Atlas data portal, we constructed a gene coexpression network. PET parameters including lesion-to-blood-pool ratio, metabolic tumor volume, and tumor lesion glycolysis were calculated. The Pearson correlation test was performed between module eigengene-the first principal component of modules' expression profile-and the PET parameters. The significantly correlated module was functionally annotated with gene ontology terms, and its hub genes were identified. Survival analysis of the significantly correlated module was performed. Results: We identified 9 coexpression network modules from the preprocessed RNA sequence data. A network module was significantly correlated with total lesion glycolysis as well as maximum and mean ¹⁸F-FDG uptake. The expression profiles of hub genes of the network were inversely correlated with ¹⁸F-FDG uptake. The significantly annotated gene ontology terms of the module were associated with immune cell activation and aggregation. The module demonstrated significant association with overall survival, and the group with higher module eigengene showed better survival than the other groups with statistical significance (P = 0.022). Conclusion: We showed that a gene network that accounts for immune cell microenvironment was associated with ¹⁸F-FDG uptake as well as prognosis in HNSCC. Our result supports the idea that competition for glucose between cancer cell and immune cell plays an important role in cancer progression associated with hypermetabolic features. In the future, PET parameters could be used as a surrogate marker of HNSCC for estimating molecular status of immune cell microenvironment.

Functional ferritin nanoparticles for biomedical applications

Ferritin, a major iron storage protein with a hollow interior cavity, has been reported recently to play many important roles in biomedical and bioengineering applications. Owing to the unique architecture and surface properties, ferritin nanoparticles offer favorable characteristics and can be either genetically or chemically modified to impart functionalities to their surfaces, and therapeutics or probes can be encapsulated in their interiors by controlled and reversible assembly/disassembly. There has been an outburst of interest regarding the employment of functional ferritin nanoparticles in nanomedicine. This review will highlight the recent advances in ferritin nanoparticles for drug delivery, bioassay, and molecular imaging with a particular focus on their biomedical applications.

Study of LAT1 Expression in Brain Metastases: Towards a Better Understanding of the Results of Positron Emission Tomography Using Amino Acid Tracers

Positron emission tomography using radiolabeled amino acid (PET-AA) appears to be promising in distinguishing between recurrent tumour and radionecrosis in the follow-up of brain metastasis (BM). The amino acid transporter LAT1 and its cofactor CD98, which are involved in AA uptake, have never been investigated in BM. The aim of our study was to determine and compare the expression of LAT1 and CD98 in BM and in non-tumoral brain tissue (NT). The expression of LAT1 and CD98 were studied by immunohistochemistry in 67 BM, including 18 BM recurrences after radiotherapy, in 53 NT, and in 13 cases of patients with previously irradiated brain tumor and investigated by [18F] FDOPA-PET. LAT1 and CD98 expression were detected in 98.5% and 59.7% of BM respectively and were significantly associated with BM tissue as compared to NT (p<0.001). LAT1 expression in recurrent BM was significantly increased as compared to newly occurring BM. Ten cases investigated by [18F] FDOPA-PET corresponding to recurrent BM displayed significant [18F] FDOPA uptake and LAT1 overexpression whereas three cases corresponding to radionecrosis showed no or low uptake and LAT1 expression. LAT1 expression level and [18F] FDOPA uptake were significantly correlated. In conclusion, we hypothesized that BM may overexpress the AA transporter LAT1. We have shown that LAT1 overexpression was common in BM and was specific for BM as compared to healthy brain. These results could explain the specific BM uptake on PET-AA.

Diagnostic Performance of Whole-Body PET/MRI for Detecting Malignancies in Cancer Patients: A Meta-Analysis

Background

As an evolving imaging modality, PET/MRI is preliminarily applied in clinical practice. The aim of this study was to assess the diagnostic performance of PET/MRI for tumor staging in patients with various types of cancer.

Methods

Relevant articles about PET/MRI for cancer staging were systematically searched in PubMed, EMBASE, EBSCO and the Cochrane Library. Two researchers independently selected studies, extracted data and assessed the methodological quality using the QUADAS tool. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated per patient and per lesion. The summary receiver-operating characteristic (SROC) curves were also constructed, and the area under the curve (AUC) and Q* estimates were obtained.

Results

A total of 38 studies that involved 753 patients and 4234 lesions met the inclusion criteria. On a per-patient level, the pooled sensitivity and specificity with 95% confidence intervals (CIs) were 0.93 (0.90–0.95) and 0.92 (0.89–0.95), respectively. On a per-lesion level, the corresponding estimates were 0.90 (0.88–0.92) and 0.95 (0.94–0.96), respectively. The pooled PLR, NLR and DOR estimates were 6.67 (4.83–9.19), 0.12 (0.07–0.21) and 75.08 (42.10–133.91) per patient and 10.91 (6.79–17.54), 0.13 (0.08–0.19) and 102.53 (59.74–175.97) per lesion, respectively.

Conclusion

According to our results, PET/MRI has excellent diagnostic potential for the overall detection of malignancies in cancer patients. Large, multicenter and prospective studies with standard scanning protocols are required to evaluate the diagnostic value of PET/MRI for individual cancer types.

Quantification of metabolic tumor activity and burden in patients with non-small-cell lung cancer: Is manual adjustment of semiautomatic gradient-based measurements necessary?

PURPOSE

Metabolic tumor burden (MTB) measurements including metabolic tumor volume and total lesion glycolysis have been shown to have prognostic value in non-small-cell lung cancer (NSCLC). The calculation of MTB typically utilizes software to semiautomatically draw volumes of interest around the tumor, which are subsequently manually adjusted by the radiologist to include the entire tumor. The manual adjustment step can be time-consuming and observer-dependent. We compared the agreement of MTB values obtained using the semiautomatic method with and without manual adjustment in NSCLC patients.

METHODS

This IRB-approved prospective study included 134 patients with histologically proven NSCLC who underwent fluorine-18 fluorodeoxyglucose PET/computed tomography. The MTB of the primary tumor was measured with a semiautomatic gradient-based method without manual adjustment (the semiautomatic gradient method) and with manual adjustment (the manually adjusted semiautomatic gradient method) by two radiologists using the MIM PETedge tool. The paired t-test, Wilcoxon signed-rank test, and concordance correlation coefficient (CCC) were calculated to evaluate the agreement between MTB measures obtained with these two methods, as well as agreement between the two radiologists for each method.

RESULTS

Maximum standardized uptake value was identical between the two methods. No statistically significant difference was present for peak standardized uptake value, metabolic tumor volume, and total lesion glycolysis values between the two methods (P=0.23, 0.45, and 0.37, respectively). Excellent agreement between the two methods was found in terms of CCC (CCC>0.98 for all measures). Interobserver reliability was excellent for all measures (CCC>0.90).

CONCLUSION

The semiautomatic gradient-based tumor-segmentation method can be used without the additional manual adjustment step for MTB quantification of primary NSCLC tumors.

[18F]Fluorodeoxyglucose (FDG)-Positron Emission Tomography (PET)/Computed Tomography (CT) in Suspected Recurrent Breast Cancer: A Prospective Comparative Study of Dual-Time-Point FDG-PET/CT, Contrast-Enhanced CT, and Bone Scintigraphy

PURPOSE

To prospectively investigate the diagnostic accuracy of [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) with dual-time-point imaging, contrast-enhanced CT (ceCT), and bone scintigraphy (BS) in patients with suspected breast cancer recurrence.

PATIENTS AND METHODS

One hundred women with suspected recurrence of breast cancer underwent 1-hour and 3-hour FDG-PET/CT, ceCT, and BS within approximately 10 days. The study was powered to estimate the precision of the individual imaging tests. Images were visually interpreted using a four-point assessment scale, and readers were blinded to other test results. The reference standard was biopsy along with treatment decisions and clinical follow-up (median, 17 months).

RESULTS

FDG-PET/CT resulted in no false negatives and fewer false positives than the other imaging techniques. Accuracy of results were similar for 1-hour and 3-hour FDG-PET/CT. For distant recurrence, the area under the receiver operating curve was 0.99 (95% CI, 0.97 to 1) for FDG-PET/CT, 0.84 (95% CI, 0.73 to 0.94) for ceCT, and 0.86 (95% CI, 0.77 to 0.94) for the combined ceCT+BS. Of 100 patients, 22 (22%) were verified with distant recurrence, and 18 of these had bone involvement. Nineteen patients (19%) had local recurrence only. In exploratory analyses, diagnostic accuracy of FDG-PET/CT was better than ceCT alone or ceCT combined with BS in diagnosing distant, bone, and local recurrence, shown by a greater area under the receiver operating curve and higher sensitivity, specificity, and superior likelihood ratios.

CONCLUSION

FDG-PET/CT was accurate in diagnosing recurrence in breast cancer patients. It allowed for distant recurrence to be correctly ruled out and resulted in only a small number of false-positive cases. Exploratory findings suggest that FDG-PET/CT has greater accuracy than conventional imaging technologies in this patient group.

Value of FDG PET/CT in staging of oral cancer: four simultaneous primary malignancies

Patients with squamous cell cancer (SCC) of the head and neck are at increased risk for second primary malignancies (SPMs). We report on a 53-year-old patient with primary diagnosis of SCC in the anterior floor of the mouth. Panendoscopy suspected an SPM of the right vocal cord. FDG PET/CT, as a whole-body imaging method, confirmed this suspicion and raised concern for further SPM of both esophagus and colon. All malignancies were confirmed by biopsy. Subsequently, the patient underwent radiochemotherapy. In summary, FDG PET/CT revealed unexpected multiple SPMs, prevented unnecessary resection of the oral SCC, and enabled individualized therapeutic management.

PET/CT imaging correlates with treatment outcome in patients with multidrug-resistant tuberculosis

Definitive clinical trials of new chemotherapies for treating tuberculosis (TB) require following subjects until at least 6 months after treatment discontinuation to assess for durable cure, making these trials expensive and lengthy. Surrogate endpoints relating to treatment failure and relapse are currently limited to sputum microbiology, which has limited sensitivity and specificity. We prospectively assessed radiographic changes using 2-deoxy-2-[(18)F]-fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) at 2 and 6 months (CT only) in a cohort of subjects with multidrug-resistant TB, who were treated with second-line TB therapy for 2 years and then followed for an additional 6 months. CT scans were read semiquantitatively by radiologists and were computationally evaluated using custom software to provide volumetric assessment of TB-associated abnormalities. CT scans at 6 months (but not 2 months) assessed by radiologist readers were predictive of outcomes, and changes in computed abnormal volumes were predictive of drug response at both time points. Quantitative changes in FDG uptake 2 months after starting treatment were associated with long-term outcomes. In this cohort, some radiologic markers were more sensitive than conventional sputum microbiology in distinguishing successful from unsuccessful treatment. These results support the potential of imaging scans as possible surrogate endpoints in clinical trials of new TB drug regimens. Larger cohorts confirming these results are needed.

Comparison of the diagnostic performance of 18F-fluorothymidine versus 18F-fluorodeoxyglucose positron emission tomography on pulmonary lesions: A meta analysis

A pulmonary lesion is an extremely common and clinically challenging disorder worldwide, and an accurate diagnosis of lung cancer is crucial for early treatment and management. The aim of the present study was to perform a comprehensive meta analysis to compare the diagnostic performance of ¹⁸F-fluorothymidine (¹⁸F-FLT) positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET in evaluating patients with pulmonary lesions. Relevant studies were identified using the PubMed, EMBASE and Cochrane library databases. The pooled estimated sensitivity, specificity, positive-likelihood ratio, negative-likelihood ratio, and diagnostic odds ratio (DOR) for ¹⁸F-FLT PET versus ¹⁸F-FDG PET were calculated as the main outcome measures. Summary receiver operating characteristic curves were also constructed by Meta-Disk 1.4 software using a Mose's constant of linear model. The meta analysis showed that ¹⁸F-FLT PET had a higher specificity (0.70; 95% CI, 0.61-0.77), but lower sensitivity (0.81; 95% CI, 0.74-0.87) compared to ¹⁸F-FDG PET (0.50; 95% CI, 0.41-0.58 for specificity; 0.92; 95% CI 0.86-0.95 for sensitivity). For DOR, ¹⁸F-FLT PET (12.58; 95% CI, 6.81-23.24) was higher compared to ¹⁸F-FDG PET (10.72; 95% CI, 5.51-20.87). The area under the curve was 0.8592 and 0.9240 for ¹⁸F-FLT PET and ¹⁸F-FDG PET, respectively (Z=0.976, P>0.05). In conclusion, ¹⁸F-FLT PET and ¹⁸F-FDG PET had good diagnostic performance for the overall assessment of pulmonary lesions, and ¹⁸F-FLT PET had a higher specificity compared to ¹⁸F-FDG PET, but was less sensitive than ¹⁸F-FDG PET. Therefore, ¹⁸F-FLT and ¹⁸F-FDG together could add diagnostic confidence for pulmonary lesions.

Prognostic value of volumetric parameters of (18)F-FDG PET in non-small-cell lung cancer: a meta-analysis

PURPOSE

We conducted a comprehensive systematic review of the literature on volumetric parameters from (18)F-FDG PET and a meta-analysis of the prognostic value of metabolic tumour volume (MTV) and total lesion glycolysis (TLG) in patients with lung cancer.

METHODS

A systematic search of MEDLINE and EMBASE was performed using the keywords "positron emission tomography (PET)", "lung cancer", and "volume". Inclusion criteria were: (18)F-FDG PET used as an initial imaging tool; studies limited to non-small-cell lung cancer (NSCLC); volume measurement of lung cancer; patients who had not undergone surgery, chemotherapy, or radiotherapy before the PET scan; and studies that reported survival data. Event-free survival and overall survival were evaluated as outcomes. The impact of MTV and TLG on survival was measured in terms of the hazard ratio (HR) effect size. Data from each study were analysed using Review Manager 5.2.

RESULTS

Thirteen eligible studies including 1,581 patients were analysed. Patients with high MTV showed a worse prognosis with an HR of 2.71 (95% CI 1.82 - 4.02, p < 0.00001) for adverse events and an HR of 2.31 (95% CI 1.54 - 3.47, p < 0.00001) for death. Patients with high TLG also showed a worse prognosis with an HR of 2.35 (95% CI 1.91 - 2.89, p < 0.00001) for adverse events and an HR of 2.43 (95% CI 1.89 - 3.11, p < 0.00001) for death. The prognostic value of MTV and TLG remained significant in a subgroup analysis according to TNM stage as well as the methods for defining cut-off values and tumour delineation.

CONCLUSION

Volumetric parameters from (18)F-FDG PET are significant prognostic factors for outcome in patients with NSCLC. Patients with a high MTV or TLG are at higher risk of adverse events and death. MTV and TLG were significant prognostic factors in patients with TNM stage I/II and stage III/IV NSCLC.

Main controversies in breast cancer

In this article, we have reviewed available evidence for diagnosis, treatment, and follow-up in female breast cancer (BC). Into daily clinical practice some controversies are occurred. Especially, in the diagnosis field, despite the fact that the optimal age in which screening mammography should start is a subject of intense controversy, there is a shift toward the beginning at the age of 40 although it is suggested that the net benefit is small for women aged 40 to 49 years. In addition, a promising tool in BC screening seems to be breast tomosynthesis. Other tools such as 3D ultrasound and shear wave elastography (SWE) are full of optimism in BC screening although ultrasonography is not yet a first-line screening method and there is insufficient evidence to recommend the systemic use of the SWE for BC screening. As for breast magnetic resonance imaging (MRI), even if it is useful in BC detection in women who have a strong family history of BC, it is not generally recommended as a screening tool. Moreover, based on the lack of randomized clinical trials showing a benefit of presurgical breast MRI in overall survival, it's integration into breast surgical operations remains debatable. Interestingly, in contrast to fine needle aspiration, core biopsy has gained popularity in presurgical diagnosis. Furthermore, after conservative surgery in patients with positive sentinel lymph nodes, the recent tendency is the shift from axillary dissection to axillary conserving strategies. While the accuracy of sentinel lymph node after neoadjuvant chemotherapy and second BC surgery remains controversial, more time is needed for evaluation and for determining the optimal interval between the two surgeries. Additionally, in the decision between immediate or delayed breast reconstruction, there is a tendency in the immediate use. In the prevention of BC, the controversial issue between tamoxifen and raloxifene becomes clear with raloxifene be more profitable through the toxicities of tamoxifen. However, the prevention of bone metastasis with bisphosphonates is still conflicting. Last but not least, in the follow-up of BC survivors, mammography, history and physical examination are the means of an early detection of BC recurrence. ed.

Prognostic value of metabolic tumor burden in lung cancer

Accurate prognosis in patients with lung cancer is important for clinical decision making and treatment selection. The TNM staging system is currently the main method for establishing prognosis. Using this system, patients are grouped into one of four stages based on primary tumor extent, nodal disease, and distant metastases. However, each stage represents a range of disease extent and may not on its own be the best reflection of individual patient prognosis. (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) can be used to evaluate the metabolic tumor burden affecting the whole body with measures such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). MTV and TLG have been shown to be significant prognostic factors in patients with lung cancer, independent of TNM stage. These metabolic tumor burden measures have the potential to make lung cancer staging and prognostication more accurate and quantitative, with the goal of optimizing treatment choices and outcome predictions.

[Rational radiological diagnostics of pneumonia]

As one of the most common infectious diseases pneumonia is associated with a high morbidity and mortality. A rapid and rational diagnostic work-up is crucial to improve patient prognosis and outcome. The diagnosis of pneumonia requires the detection of pulmonary infiltrates; therefore, radiological methods are a key part of the diagnostic algorithm to demonstrate the presence of infiltrates and to confirm the diagnosis. The accepted standard method is chest X-ray at two levels, posteroanterior (PA) and lateral radiographs. Computed tomography is mainly used for immunocompromised patients, patients with pre-existing structural lung disease, therapy refractory pneumonia and in the differential diagnosis of suspected underlying diseases, such as pulmonary embolism or malignancy. Increasing evidence suggests that lung ultrasound is a promising, precise technology which is readily available and with no irradiation of patient.

PET/CT in Oncology: Current Status and Perspectives

The discovery of the Warburg effect in the early twentieth century followed by the development of the fluorinated glucose analogue 18F-fluorodeoxyglucose (18F-FDG) and the invention of positron emission tomographs laid the foundation of clinical PET/CT. This review discusses the challenges and obstacles in clinical adoption of this technique. We then discuss advances in instrumentation, including the critically important introduction of PET/CT and current PET/CT protocols. Moreover, we provide evidence for the clinical utility of PET/CT for patient management and its potential impact on patient outcome, and address its cost and cost-effectiveness. Although this review largely focuses on 18F-FDG imaging, we also discuss a variety of additional molecular imaging approaches that can be used for cancer phenotyping with PET. Throughout this review we emphasize the critical contributions of CT to the strength of PET/CT.