Distinct genomic landscapes of gastroesophageal adenocarcinoma depending on PD-L1 expression identify mutations in RAS-MAPK pathway and TP53 as potential predictors of immunotherapy efficacy

BACKGROUND

The impact of molecular alterations on programmed death-ligand 1 (PD-L1) combined positive score (CPS) is not well studied in gastroesophageal adenocarcinomas (GEAs). We aimed to characterize genomic features of tumors with different CPSs in GEAs.

PATIENTS AND METHODS

Genomic alterations of 2518 GEAs were compared in three groups (PD-L1 CPS ≥ 10, high; CPS = 1-9, intermediate; CPS < 1, low) using next-generation sequencing. We assessed the impact of gene mutations on the efficacy of immune checkpoint inhibitors (ICIs) and tumor immune environment based on the Memorial Sloan Kettering Cancer Center and The Cancer Genome Atlas databases.

RESULTS

High, intermediate, and low CPSs were seen in 18%, 54% and 28% of GEAs, respectively. PD-L1 positivity was less prevalent in women and in tissues derived from metastatic sites. PD-L1 CPS was positively associated with mismatch repair deficiency/microsatellite instability-high, but independent of tumor mutation burden distribution. Tumors with mutations in KRAS, TP53, and RAS-mitogen-activated protein kinase (MAPK) pathway were associated with higher PD-L1 CPSs in the mismatch repair proficiency and microsatellite stability (pMMR&MSS) subgroup. Patients with RAS-MAPK pathway alterations had longer overall survival (OS) from ICIs compared to wildtype (WT) patients [27 versus 13 months, hazard ratio (HR) = 0.36, 95% confidence interval (CI): 0.19-0.7, P = 0.016] and a similar trend was observed in the MSS subgroup (P = 0.11). In contrast, patients with TP53 mutations had worse OS from ICIs compared to TP53-WT patients in the MSS subgroup (5 versus 21 months, HR = 2.39, 95% CI: 1.24-4.61, P = 0.016).

CONCLUSIONS

This is the largest study to investigate the distinct genomic landscapes of GEAs with different PD-L1 CPSs. Our data may provide novel insights for patient selection using mutations in TP53 and RAS-MAPK pathway and for the development of rational combination immunotherapies in GEAs.

IPO5 promotes malignant progression of esophageal cancer through activating MMP7

OBJECTIVE

Previous studies have found that IPO5 is a cancer-promoting gene. However, the role of IPO5 in esophageal cancer has not been reported. This study aims to investigate the expression characteristics of IPO5 in esophageal cancer, and to further analyze its relationship with clinical parameters and prognosis of esophageal cancer.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to examine the expression of matrix metalloproteinase 7 (MMP7) in 45 pairs of tumor tissue specimens and adjacent normal ones collected from esophageal cancer patients. The correlation between IPO5 expression and clinical indicators and prognosis of esophageal cancer patients was analyzed. Meanwhile, IPO5 expression in esophageal cancer cell lines was also detected using qRT-PCR. In addition, the influence of IPO5 on esophageal cancer cell functions was analyzed using cell counting kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Finally, Dual-Luciferase reporter assay and cell reverse experiments were conducted to explore its underlying mechanisms.

RESULTS

In this experiment, qRT-PCR results indicated that IPO5 expression in tumor tissues of esophageal cancer patients was significantly higher than that in adjacent normal ones, and the difference was statistically significant. Compared with esophageal cancer patients with low expression of IPO5, those with high expression of IPO5 had higher pathological stage and lower overall survival rate. Compared with control group, the proliferation ability of esophageal cancer cells in IPO5 knockdown group was significantly decreased. In addition, Western Blot results indicated that the key protein MMP7 was conspicuously elevated in the esophageal cancer cell line after knockdown of IPO5. Dual-Luciferase reporter assay results suggested that IPO5 can specifically bind MMP7. Additionally, the cell reverse experiment demonstrated that MMP7 was responsible for IPO5-regulated malignant progression of esophageal cancer.

CONCLUSIONS

IPO5 expression significantly increased in esophageal cancer tissues, which was associated with pathological staging and poor prognosis of esophageal cancer patients. IPO5 may promote malignant progression of esophageal cancer through the regulation of MMP7.

S-phase kinase-associated protein-2 (Skp2) promotes nucleus pulposus cell proliferation by inhibition of p27 in attenuating intervertebral disc degeneration

OBJECTIVE

Nucleus pulposus (NP) cell proliferation plays a key role during the process of intervertebral disc degeneration (IDD). S-phase kinase-associated protein-2 (Skp2) has been proved as an important regulator for cell growth factors in vitro. Nonetheless, whether Skp2 attenuates IDD by mediating NP cell proliferation still remains unclear. Therefore, the aim of this study was to explore how Skp2 affected NP cell proliferation and the potential mechanism in vitro.

PATIENTS AND METHODS

In this study, we first collected different degenerated human NP samples and isolated NP cells from these tissues. NP cell degenerated model was established with IL-1β, and the cells were transfected with lentivirus to achieve Skp2 overexpression. Besides, SKPinC1 was used to suppress Skp2 expression in vitro. Western blot, RT-PCR, and immunocytofluorescence were applied to detect genetic differences among groups. Furthermore, cell viability and cell cycle were determined by CCK-8 assay and flow cytometry, respectively.

RESULTS

Skp2 expression decreased significantly in degenerated disc samples (p<0.05). IL-1β stimulation significantly promoted NP cell degeneration, which could be reversed by Skp2 overexpression (p<0.05). Meanwhile, Skp2 in IDD significantly inhibited the expression level of medial p27 and promoted cell cycle by CDK2 activation (p<0.05). In addition, Skp2 suppression affected NP cell proliferation in vitro.

CONCLUSIONS

NP cells exhibited significantly inhibited proliferation ability when down-regulated the expression level of Skp2. Our findings provided a more meritorious viewpoint of Skp2 in NP cell proliferation. Furthermore, the above results suggested that Skp2 was a novel target in the treatment of IDD.

[Effect of piRNA NU13 in regulating biological behaviors of human Wilms tumor cells in vitro]

OBJECTIVE

To investigate the role of the differential piRNA NU13 derived from piwil2-induced cancer stem-like cells (piwil2-iCSCs) in regulating biological behaviors of Wilms tumor cells (G401).

OBJECTIVE

The expressions of piRNA NU13 and NOP56 were detected in Wilms tumor cell line G401 using RT-qPCR. G401 cells were transfected with piRNA NU13 mimics and inhibitor for its over-expression and inhibition, and the transfection efficiency was verified with RT-qPCR. The changes in proliferation of G401 cells after transfection were detected using CCK8 assay, and cell apoptosis was analyzed using flow cytometry. Wound healing assay and Transwell assay were performed to examine the changes in migration and invasion abilities of the transfected cells. The binding of NOP56 and piRNA NU13 was detected using dual luciferase experiment. The protein expressions of MMP2, MMP9, BAX, Bcl2, and NOP56 in the cells were detected with Western blotting.

OBJECTIVE

RTqPCR showed that the expression of piRNA NU13 decreased significantly in human Wilms tumor G401 cells as compared with that in renal tubular epithelial cell line HK2 (P < 0.05), and NOP56 was highly expressed in G401 cells and Wilms tumor tissues (P < 0.05). Over-expression of piRNA NU13 significantly suppressed the proliferation, migration and invasion of G401 cells, promoted cell apoptosis (P < 0.05), inhibited the expression of MMP2, MMP9 and Bcl2, and enhanced the expression of BAX (P < 0.05). The results of dual luciferase experiment showed that piRNA NU13 did not bind to NOP56 directly but regulated the expression of NOP56 in an indirect manner.

OBJECTIVE

piRNA NU13 is down-regulated and NOP56 is highly expressed in Wilms tumor. piNU13 may regulate the expression of NOP56 indirectly to inhibit the proliferation, migration and invasion and promote apoptosis of Wilms tumor cells in vitro.

Real-time observation of microcirculatory leukocytes in patients undergoing major liver resection

Ischemia/reperfusion injury and inflammation are associated with microcirculatory dysfunction, endothelial injury and glycocalyx degradation. This study aimed to assess microcirculation in the sublingual, intestinal and the (remnant) liver in patients undergoing major liver resection, to define microcirculatory leukocyte activation and its association with glycocalyx degradation. In this prospective observational study, the microcirculation was assessed at the beginning of surgery (T0), end of surgery (T1) and 24 h after surgery (T2) using Incident Dark Field imaging. Changes in vessel density, blood flow and leukocyte behaviour were monitored, as well as clinical parameters. Syndecan-1 levels as a parameter of glycocalyx degradation were analysed. 19 patients were included. Sublingual microcirculation showed a significant increase in the number of rolling leukocytes between T0 and T1 (1.5 [0.7-1.8] vs. 3.7 [1.7-5.4] Ls/C-PCV/4 s respectively, p = 0.001), and remained high at T2 when compared to T0 (3.8 [3-8.5] Ls/C-PCV/4 s, p = 0.006). The microvascular flow decreased at T2 (2.4 ± 0.3 vs. baseline 2.8 ± 0.2, respectively, p < 0.01). Duration of vascular inflow occlusion was associated with significantly higher numbers of sublingual microcirculatory rolling leukocytes. Syndecan-1 increased from T0 to T1 (42 [25-56] vs. 107 [86-164] ng/mL, p < 0.001). The microcirculatory perfusion was characterized by low convection capacity and high number of rolling leukocytes. The ability to sublingually monitor the rolling behaviour of the microcirculatory leukocytes allows for early identification of patients at risk of increased inflammatory response following major liver resection.

[Pulmonary mucosa-associated lymphoid tissue lymphoma concurrent with lung squamous cell carcinoma: a case report and literature review]

Objective: To explore the clinical manifestations, imaging features, pathological features, diagnosis and treatment of pulmonary mucosal-associated lymphoid tissue(MALT)lymphoma concurrent with lung squamous cell carcinoma, and to improve the understanding of this disease. Methods: Using "Pulmonary mucosa-associated lymphoid tissue, squamous cell carcinoma" as the search term, from January 1, 1983 to August 31, 2020, a total of 3 cases were retrieved in the PubMed database. In the Wanfang database, using "Lung mucosa-associated lymphoid tissue, lung squamous cell carcinoma" as the search term, from January 1, 1990 to August 31, 2020, a total of 1 related document was retrieved. In the CNKI database, "(lung) mucosa-associated lymphoid tissue lymphoma, (lung) squamous cell carcinoma" was used as the search term, and no relevant case reports were retrieved. Results: A 64-year-old man was admitted to the hospital because of chest tightness and shortness of breath for 10 days, cough and fever for one day. Enhanced CT of the chest showed a soft tissue mass shadow in the right lower hilar area, with obstruction of the adjacent bronchus, and local mild enhancement, suggesting of right lower lung cancer. In addition, the CT scan also showed consolidated shadows in the lower lobes of both lungs, scattered nodules, multiple lymphadenopathy in the mediastinum, and a small amount of pleural effusion on the right. Under bronchoscopy, a cauliflower-like neoplasm was seen at the opening of the lower right basal section, about 7 mm×8 mm, and biopsy showed that part of the mucosal structure was destroyed, with disappearance of the squamous epithelial layer, and the nuclei were large and deeply stained, and some were distributed in nests, with poor keratinization and a small amount of necrosis, and fibrous tissue reaction. Immunostaining revealed that the tumor was positive for p40, CK5/6 and EGFR and negative forTTF-1, NapsinA, PD-L1, p53, with about 30% Ki-67 positive cells. A puncture biopsy of the right lower lobe showed that the alveolar cavity was filled with nested lymphoid cells, consisting of small lymphocytes, central cell-like cells and monocyte-like cells, with occasionally large cells. Immunostaining revealed CD₂₀⁺, CD_79a⁺, scattered CD₃+, Bcl2+, SMA vascular+, Bcl6-, CK-, CD10-, CyclinD1-, with about 3% Ki-67 positive cells. The histopathological examinations confirmed the diagnosis of mucosal-associated lymphoid tissue extranodal marginal zone lymphoma(MALT lymphoma),and lung squamous cell carcinoma. Conclusions: Pulmonary mucosa-associated lymphoid tissue lymphoma complicated with lung squamous cell carcinoma is rare and easy to be missed and misdiagnosed. Chest CT imaging shows single or multiple nodules, mass shadows or consolidation, often accompanied by air-bronchial signs in the lesion, bronchiectasis, ground glass density around the lesion, hilar and mediastinal lymphadenopathy. Occasionally, pleural effusion can be seen. Lung biopsy is the gold standard for diagnosis.

Status of insecticide resistance and biochemical characterization of chlorpyrifos resistance in Sogatella furcifera (Hemiptera:Delphacidae) in Sichuan Province, China

The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera, Delphacidae), is an energetic rice insect pest in rice production or rice-growing areas. Due to excessive use of the chemical insecticide, S. furcifera has produced the high resistance to some frequently used insecticides. In this paper, the resistance levels of S. furcifera from the eight different areas of Sichuan Province against the five chemicals were monitored by using the rice seedling dipping during 2017-2018 to understand the resistance levels. The results showed that most of all populations have developed low or moderate level of resistance for chlorpyrifos (3.4 to 44.3-fold) and thiamethoxam (3.9- to 15.5-fold), the populations in the LS (1.7 to 5.4- fold)and WS (1.6 to 5.0- fold) regions were still sensitive or low resistance levels compared with other local populations. Almost all populations displayed the susceptible to imidacloprid (0.9- to 5.0-fold), buprofezin (0.9- to 4.3-fold) or low levels of resistance to pymetrozine (1.5- to 6.8-fold). The synergism experiment indicated that P450 enzymes may be important contributed to the metabolic detoxification of chlorpyrifos. The cross-resistance bioassay showed that there was no cross-resistance between chlorpyrifos and triflumezopyrim, but for sulfoxaflor, in the XY17 population. The relative expression level of twelve insecticide resistant-related P450 genes were analyzed by using qRT-PCR and found that CYP4C77, CYP418A1, CYP418A2, CYP408A3 and CYP6ER4 were significantly more expressed in the 3rd-instar nymph of the XY17 and XY18 field populations. To determine the main resistant-related P450 gene for chlorpyrifos, the relative expression level of five P450 genes were detected by using qRT-PCR from the G2 and G4 generation of XY17 under the pressure with LC₅₀ of chlorpyrifos. The results showed that CYP6ER4 was significantly up-regulated expression in XY17 G2 and G4 generations population over 700-fold (P < 0.01). The full length and proteins tertiary structure were also cloned and predicted. Meanwhile, the function of CYP6ER4 was analyzed by RNA interference and the results indicated that the relative expression of CYP6ER4 in the XY17 (G4) population after injected dsRNA was lower than that in the dsGFP injected group. Moreover, the mortality rates of the S. furcifera treated with the LC₅₀ concentration of chlorpyrifos after dsRNA microinjection was significantly higher than that of the dsGFP injected group 72 h after treatment (P < 0.01). Therefore, the overexpression of CYP6ER4 may be one of the primary factors in the development of chlorpyrifos resistance in S. furcifera.

[Current status and research progress of third-line treatment for patients with gastric cancer in China]

Gastric cancer (GC) is one of the most common malignant tumors in the world. The prognosis of advanced GC is extremely poor, characterized by the high recurrence or disease progression rate after the first-line chemotherapy, and the extremely low long-term survival rate. Meanwhile, the options for subsequent treatment are limited. Studies have shown that the third-line therapy can provide significant survival benefits for selected patients with advanced GC. Currently, a series of randomized controlled trials and real-world studies related to chemotherapy, targeted therapy, and immunotherapy are conducted. In addition, the explorations of combination therapy, and screening the optimal clinical features or predictive biomarkers for the suitable population who might benefit from the third-line regimens are the hot spots for researchers. This article will provide a detailed overview of the current status and progress of the third-line treatment for advanced GC, and to illustrate the characteristics of Chinese GC treatment.

Quantitative material analysis using secondary electron energy spectromicroscopy

This paper demonstrates how secondary electron energy spectroscopy (SEES) performed inside a scanning electron microscope (SEM) can be used to map sample atomic number and acquire bulk valence band density of states (DOS) information at low primary beam voltages. The technique uses an electron energy analyser attachment to detect small changes in the shape of the scattered secondary electron (SE) spectrum and extract out fine structure features from it. Close agreement between experimental and theoretical bulk valance band DOS distributions was obtained for six different test samples, where the normalised root mean square deviation ranged from 2.7 to 6.7%. High accuracy levels of this kind do not appear to have been reported before. The results presented in this paper point towards SEES becoming a quantitative material analysis companion tool for low voltage scanning electron microscopy (LVSEM) and providing new applications for Scanning Auger Microscopy (SAM) instruments.

The value of coronary artery calcium scores based on non-gated chest CT in predicting perioperative cardiovascular risk in patients with lower-risk lung cancer surgery

Objectives

This study evaluated whether coronary artery calcium scores (CACS) that were measured with non-gated chest CT predicted perioperative cardiovascular events in patients who were undergoing lower-risk lung cancer surgery.

Method

In this retrospective single center study, we evaluated 3112 consecutive lung cancer patients with non-gated chest CT before low-medium risk surgeries in 2017. We measured CACS and assessed clinical risk factors according to the revised cardiac risk index (RCRI) scores and predictable surgery factors. Perioperative cardiovascular events were defined as cardiac death, acute coronary syndrome, pulmonary edema, atrial and ventricular arrhythmia with hemodynamic compromise, and complete heart block during hospitalization.

Result

83 patients (2.7%) had perioperative cardiac events, 71 (85.5%) of them were atrial fibrillation. Coronary calcification CT findings were seen in 761 (24.5%) patients. CACS were associated with incidence of cardiac events (p&lt;0.001). In the receiver-operating characteristic (ROC) curve analysis of CACS for prediction of cardiac events, the cutoff value was 1 (sensitivity, 0.60; specificity, 0.75; area under the curve, 0.680). In the multivariate analysis, CACS &gt;1 (OR=1.75, 95% CI: 1.08–2.84, p=0.023), age (OR=1.06, 95% CI: 1.03–1.10, p&lt;0.001), pulmonary function classification (p&lt;0.001) and thoracotomy (OR=3.06, 95% CI: 1.78–5.26, p&lt;0.001) were predictive of cardiovascular complications.

Conclusion

Predicative value of CACS based on non-gated chest CT is high for perioperative cardiovascular risk in lung cancer patients with lower-risk lung surgery. It may be considered as a valuable tool for preoperative risk assessment in these patients without additional testing.

Funding Acknowledgement

Type of funding source: None

PEAR1 rs12041331 polymorphisms and the risk of adverse cardiovascular outcomes in patients with acute coronary syndrome and/or percutaneous coronary intervention: a systematic review and meta-analysis

Background

Platelet endothelial aggregation receptor-1 (PEAR1), expressed in endothelium, platelets, and other tissues, is a platelet transmembrane tyrosine kinase receptor involved in platelet aggregation and platelet-platelet contact. The minor allele (A) in intron 1 of the PEAR1 gene (rs12041331, G&gt;A) is associated with an reduced PEAR1 protein expression and suppressed platelet aggregation response toward multiple agonists. But current evidences on the association between PEAR1 rs12041331 polymorphisms and cardiovascular outcomes in patients with acute coronary syndrome (ACS) and/or percutaneous coronary intervention (PCI) are discordant.

Purpose

To characterize and quantify the association between PEAR1 rs12041331 polymorphisms and cardiovascular outcomes in patients with ACS and/or PCI.

Methods

We conducted a systematic review and meta-analysis by searching MEDLINE via PubMed, EMBASE, Cochrane Central Register of Controlled Trials, SinoMed, CNKI, and Wanfang Data before Dec 7, 2019 to identify studies evaluating the association between PEAR1 rs12041331 polymorphisms and cardiovascular outcomes in patients with ACS and/or PCI. The primary outcome was the major adverse cardiovascular outcomes (MACEs) defined by each study. We adopted the Mantel-Haenszel method to calculate the relative risks (RRs) with 95% confidence intervals (CIs) and the corresponding P values using the random effect model. To assess the effect of ethnicity, we performed the subgroup analyses per ethnic population using the fix effect model.

Results

Among 542 citations identified along with 1 from additional sources, we included 4 studies, which documented 218 MACEs in 8180 patients. The A allele frequency in each study was comparable with that reported in the 1000 Genome Project, but varied among ethnic populations, that is 45.8% in East Asians, 46.5% in American Africans, and 9.2% in Caucasians, adopted from the 1000 Genome Project. A-allele carriers are associated with a 54% increase in MACEs than non-A-carriers (RR, 1.54; 95% CI, 1.10–2.16; P=0.01) with a low but non-significant heterogeneity. Subgroup analyses showed that A-allele carriers tend to have more MACEs than non-A-allele carriers despite of ethnicity, that is 1.32-fold increase in East Asians (RR, 1.32; 95% CI, 0.99–1.77; P=0.06), 2.43-fold in Caucasians (RR, 2.43; 95% CI, 0.99–5.98; P=0.05), and 3.56-fold (RR, 3.56; 95% CI, 1.08–11.70; P=0.04) in American Africans.

Conclusions

Our study indicates that the PEAR1 rs12041331 is prognostic in patients with ACS and/or PCI and treated with DAPT, which might be not caused by the associations with pharmacological response to antiplatelet agents. Further investigations are thus required to address the unrevealing mechanisms of PEAR1, especially on the development of atherosclerosis and the occurrence of acute adverse ischemic events.

Figure 1

Funding Acknowledgement

Type of funding source: None

Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

SF1670 inhibits apoptosis and inflammation via the PTEN/Akt pathway and thus protects intervertebral disc degeneration

OBJECTIVE

Intervertebral disc degeneration (IVDD) is associated with the apoptosis of nucleus pulposus (NP) cells. Previous studies have shown that PTEN plays crucial roles in cell survival and apoptosis. The effect of PTEN inhibitors on cell survival following IVDD has been rarely examined. In this study, we investigated the protective effect of SF1670, as a specific PTEN inhibitor, on an in vitro NP cells degenerated model.

PATIENTS AND METHODS

We collected human disc samples from IVDD patients and detected PTEN expression in them with different degenerated degrees. NP cells were isolated from the samples and exposed to IL-1β with or without SF1670. Then, cells viability was determined by CCK-8 assay. We also measured the levels of collagen II, p16, p53, PTEN, Akt, aggrecan, caspase 3/9, Bax, Bcl-2, and several inflammatory factors in NP cells.

RESULTS

We found that the expression of PTEN markedly increased in severely degenerated disc tissues. The data showed that IL-1β upregulated the expressions of p16, p53, PTEN, caspase 3/9, and Bax, but decreased the expressions of collagen II, Akt, aggrecan, and Bcl-2. Surprisingly, the treatment with SF1670 could significantly reverse the regulatory effects of IL-1β. Moreover, relative levels of IL-6, IL-8, TNF-α, and MMP3/9/13 were significantly suppressed by SF1670 stimuli compared with IL-1β group.

CONCLUSIONS

Overall, these results demonstrated that SF1670 prevented NP degradation via suppressing apoptosis and inflammation through inhibition of PTEN and activation of Akt. SF1670 may become a novel target for the therapy of IVDD in the future.

Low-dose CT of paediatric paranasal sinus using an ultra-low tube voltage (70 kVp) combined with the flash technique

AIM

To evaluate the radiation dose and diagnostic image quality of low-dose computed tomography (CT) of the paranasal sinus in children, with acquisition at an ultra-low tube voltage (70 kVp) combined with the Flash technique.

MATERIALS AND METHODS

Eighty paediatric patients underwent CT of the paranasal sinus and were divided into two groups according to different protocols (group A: 80 kVp protocol with conventional spiral mode [n=40] and group B: 70 kVp protocol with Flash scan mode [n=40]). For each examination, the CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED) were estimated. The image noise, signal-to-noise ratio (SNR), and overall subjective diagnostic image quality were also evaluated.

RESULTS

For radiation dose, the CTDIvol (mGy), DLP (mGy·cm), and ED (mSv) values of the 70 kVp protocol were significantly lower than those of the 80 kVp protocol (CTDIvol: 1.57±0.009 versus 0.39±0.004 mGy, p<0.001; DLP: 19.88±2.01 versus 6.31±0.52 mGy·cm, p<0.001; ED: 0.079±0.016 versus 0.024±0.005 mSv, p<0.001). Compared with those of the 80-kVp protocol, the image noise increased by 40.7% (p=0.113), the SNR_soft-tissue decreased by 48.9%, and the SNR_bone increased by 10.1% with the 70-kVp protocol (p=0.176 and 0.227, respectively). There was no significant difference in the overall subjective image quality grades between these two groups (p=0.15).

CONCLUSION

When imaging the paranasal sinus in children, an ultra-low tube voltage (70 kVp) combined with the Flash CT technique can reduce the radiation dose significantly while maintaining diagnostic image quality with clinically acceptable image noise.