Hformer:highly efficient vision transformer for low-dose CT denoising

In this paper,we propose Hformer,a novel supervised learning model for low-dose computer tomography(LDCT)denoising.Hformer combines the strengths of convolutional neural networks for local feature extraction and transformer models for global feature capture.The performance of Hformer was verified and evaluated based on the AAPM-Mayo Clinic LDCT Grand Challenge Dataset.Compared with the former representative state-of-the-art(SOTA)model designs under different architectures,Hformer achieved optimal metrics without requiring a large number of learning parameters,with metrics of33.4405 PSNR,8.6956 RMSE,and 0.9163 SSIM.The experiments demonstrated designed Hformer is a SOTA model for noise suppression,structure preservation,and lesion detection.

Low-Dose CT Image Denoising Based on Improved WGAN-gp

In order to improve the quality of low-dose computational tomography (CT)images, the paper proposes an improved image denoising approach based on WGAN-gpwith Wasserstein distance. For improving the training and the convergence efficiency, thegiven method introduces the gradient penalty term to WGAN network. The novelperceptual loss is introduced to make the texture information of the low-dose imagessensitive to the diagnostician eye. The experimental results show that compared with thestate-of-art methods, the time complexity is reduced, and the visual quality of low-doseCT images is significantly improved.

Low-dose CT coronary angiography using iterative reconstruction with a 256-slice CT scanner

AIM:To explore whether computer tomography coronary angiography(CTCA) using iterative reconstruction(IR) leads to significant radiation dose reduction without a significant loss in image interpretability compared to conventional filtered back projection(FBP).METHODS:A consecutive series of 200 patients referred to our institution to undergo CTCA constituted the study population.Patients were sequentially assigned to FBP or IR.All studies were acquired with a 256-slice CT scanner.A coronary segment was considered interpretable if image quality was adequate for evaluation of coronary lesions in all segments ≥ 1.5 mm.RESULTS:The mean age was 56.3±9.6 years and165(83%) were male,with no significant differences between groups.Most scans were acquired using prospective ECG triggering,without differences between groups(FBP 84%vs IR 82%;P=0.71).A total of 3198(94%) coronary segments were deemed of diagnostic quality.The percent assessable coronary segments was similar between groups(FBP 91.7%±4.0% vs IR92.5% ± 2.8%; P=0.12).Radiation dose was significantly lower in the IR group(2.8±1.4 mSvvs 4.6±3.0mSv;P<0.0001).Image noise(37.8±1.4 HUvs 38.2±2.4 HU; P=0.20) and signal density(461.7±51.9HU vs 462.2±51.2 HU; P=0.54) levels did not differ between FBP and IR groups,respectively.The IR group was associated to significant effective dose reductions,irrespective of the acquisition mode.CONCLUSION:Application of IR in CTCA preserves image interpretability despite a significant reduction in radiation dose.

Body Pushers: Low-Dose CT, Always the Best Choice? A Study of the Diagnostic Performance of CT Scout View

Purpose: The purpose of this study has been to evaluate the diagnostic information contained in the CT scout view in the detection of body packing. Materials and methods: Retrospect analysis of 43 CT scans between July 2011 and June 2013 in asymptomatic suspects of body packing (29 men, 14 females, mean age 38 ± 9 years). Results: A total of 11 positive cases of body packing were identified. In 10 (91%) of the cases packets were relatively large and spares in number (3 or less);in 7 (64%) a single packet has been identified. 6 (55%) of the packets were located rectally, 4 (36%) vaginally and in 1 (9%) case multiple small packets of approximately 1 cm in size were found to have been ingested orally. Maximum and minimum diameters were 5.9 ± 3 cm and 2.9 ± 1.4 cm, respectively. The mean weight of packets was 7.5 ± 4.2 g (range 2 - 54 g). In 73% (n = 8) heroin had been detected;other drugs such as cocaine (n = 1) and cannabis (n = 1) were encountered once, respectively. One packet was identified retrospectively and its content could therefore not be identified. The average effective dose was 3.8 ± 2.1 mSv for CT, of that 0.12 ± 0.01 mSv was required for the CT scout view. Conclusion: If CT scout view were treated as a diagnostic image, some CT scans may be omitted, thereby maintaining streamlined operations and achieving further dose reduction jointly in the workup of body packing.

Efficacy and safety of low-dose cyclophosphamide combined with lenvatinib, pembrolizumab and TACE for unresectable hepatocellular carcinoma:A single-center, prospective,single-arm clinical trial

Objective: Unresectable hepatocellular carcinoma(uHCC) continues to pose effective treatment options. The objective of this study was to assess the efficacy and safety of combining low-dose cyclophosphamide with lenvatinib, pembrolizumab and transarterial chemoembolization(TACE) for the treatment of uHCC.Methods: From February 2022 to November 2023, a total of 40 patients diagnosed with uHCC were enrolled in this small-dose, single-center, single-arm, prospective study. They received a combined treatment of low-dose cyclophosphamide with lenvatinib, pembrolizumab, and TACE. Study endpoints included progression-free survival(PFS), objective response rate(ORR), and safety assessment. Tumor response was assessed using the modified Response Evaluation Criteria in Solid Tumors(mRECIST), while survival analysis was conducted through KaplanMeier curve analysis for overall survival(OS) and PFS. Adverse events(AEs) were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events(version 5.0).Results: A total of 34 patients were included in the study. The median follow-up duration was 11.2 [95% confidence interval(95% CI), 5.3-14.6] months, and the median PFS(mPFS) was 15.5(95% CI, 5.4-NA) months.Median OS(mOS) was not attained during the study period. The ORR was 55.9%, and the disease control rate(DCR) was 70.6%. AEs were reported in 27(79.4%) patients. The most frequently reported AEs(with an incidence rate >10%) included abnormal liver function(52.9%), abdominal pain(44.1%), abdominal distension and constipation(29.4%), hypertension(20.6%), leukopenia(17.6%), constipation(17.6%), ascites(14.7%), and insomnia(14.7%). Abnormal liver function(14.7%) had the most common grade 3 or higher AEs.Conclusions: A combination of low-dose cyclophosphamide with lenvatinib, pembrolizumab, and TACE is safe and effective for u HCC, showcasing a promising therapeutic strategy for managing uHCC.

A NONLOCAL KRONECKER-BASIS-REPRESENTATION METHOD FOR LOW-DOSE CT SINOGRAM RECOVERY

Low-dose computed tomography(LDCT)contains the mixed noise of Poisson and Gaus-sian,which makes the image reconstruction a challenging task.In order to describe the statistical characteristics of the mixed noise,we adopt the sinogram preprocessing as a stan-dard maximum a posteriori(MAP).Based on the fact that the sinogram of LDCT has non-local self-similarity property,it exhibits low-rank characteristics.The conventional way of solving the low-rank problem is implemented in matrix forms,and ignores the correlations among similar patch groups.To avoid this issue,we make use of a nonlocal Kronecker-Basis-Representation(KBR)method to depict the low-rank problem.A new denoising model,which consists of the sinogram preprocessing for data fidelity and the nonlocal KBR term,is developed in this work.The proposed denoising model can better illustrate the generative mechanism of the mixed noise and the prior knowledge of the LDCT.Nu-merical results show that the proposed denoising model outperforms the state-of-the-art algorithms in terms of peak-signal-to-noise ratio(PSNR),feature similarity(FSIM),and normalized mean square error(NMSE).

Malignant glaucoma treated by low-dose laser cycloplasty: a 1-year multicenter prospective noncomparative study

AIM:To report a one-year clinical outcomes of low-dose laser cycloplasty(LCP)among malignant glaucoma patients.METHODS:In this prospective,multicenter,noncomparative clinical study,participants with malignant glaucoma were recruited and underwent LCP at eight ophthalmic centers in China.Patients were followed up at 1wk,1,3,6,and 12mo.Intraocular pressure(IOP),number of glaucoma medications,anterior chamber depth(ACD),and complications were recorded.Anatomical success was defined as the reformation of the anterior chamber based on slit-lamp biomicroscopy.Recurrence was defined by the presence of a shallow orflat anterior chamber after initial recovery from treatment.RESULTS:A total of 34 eyes received LCP.Mean IOP and medications decreased from 36.1±11.5 mm Hg with 3.3±1.5 glaucoma medications pre-treatment to 20.9±9.8 mm Hg(P<0.001)with 2.9±1.6 medications(P=0.046)at 1d,and 17.4±6.7 mm Hg(P<0.001)with 1.3±1.7 medications(P<0.001)at 12mo.The ACD increased from 1.1±0.8 mm at baseline to 1.7±1.0 mm and to 2.0±0.5 mm at 1d and 12mo,respectively.A total of 32(94.1%)eyes achieved initial anatomical success.During follow-up,2(5.9%)eyes failed and 8(23.5%)eyes relapsed,yielding a 12-month anatomical success rate of 64.3%.Complications including anterior synechia(8.82%),choroidal/ciliary detachment(5.88%)and hypopyon(2.94%)were observed within 1wk.CONCLUSION:LCP is simple,safe,and effective in reforming the anterior chamber in malignant glaucoma.

Successful treatment of patients with refractory idiopathic membranous nephropathy with low-dose Rituximab:A single-center experience

BACKGROUND The recognition of idiopathic membranous nephropathy(IMN)as an autoimmune disease has paved the way for the use of B-cell-depleting agents,such as Rituximab(RTX),which is now a first-line drug for treating IMN with proven safety and efficacy.Nevertheless,the usage of RTX for the treatment of refractory IMN remains controversial and challenging.AIM To evaluate the efficacy and safety of a new low-dose RTX regimen for the treatment of patients with refractory IMN.METHODS A retrospective study was performed on refractory IMN patients that accepted a low-dose RTX regimen(RTX,200 mg,once a month for five months)in the Xiyuan Hospital of Chinese Academy of Chinese Medical Sciences’Department of Nephrology from October 2019 to December 2021.To assess the clinical and immune remission data,we performed a 24 h urinary protein quantification(UTP)test and measured the serum albumin(ALB)and serum creatinine(SCr)levels,phospholipase A2 receptor(PLA2R)antibody titer,and CD19+B-cell count every three months.RESULTS A total of nine refractory IMN patients were analyzed.During follow-up conducted twelve months later,the results from the 24 h UTP decreased from baseline[8.14±6.05 g/d to 1.24±1.34 g/d(P<0.05)]and the ALB levels increased from baseline[28.06±8.42 g/L to 40.93±5.85 g/L(P<0.01)].Notably,after administering RTX for six months,the SCr decreased from 78.13±16.49μmol/L to 109.67±40.87μmol/L(P<0.05).All of the nine patients were positive for serum anti-PLA2R at the beginning,and four patients had normal anti-PLA2R titer levels at six months.The level of CD19+B-cells decreased to 0 at three months,and CD19+B-cell count remained at 0 up until six months of follow-up.CONCLUSION Our low-dose RTX regimen appears to be a promising treatment strategy for refractory IMN.

Analysis of the Efficacy of Low-Dose Betaloc Combined with Amiodarone in Treating Ventricular Arrhythmia

Objective:To explore and analyze the clinical effect of low-dose Betaloc combined with amiodarone in treating ventricular arrhythmia.Methods:70 patients with ventricular arrhythmia who were admitted to the Department of Cardiology of our hospital between August 2022 and August 2023 were selected as research subjects.They were divided into two groups using the coin-tossing method:the combination group(n=35)and the reference group(n=35).The combination group was treated with low-dose Betaloc and amiodarone,and the control group was treated with low-dose Betaloc alone.The treatment efficacy,cardiac function indicators,and related tested indicators of the two groups were compared.Results:The total efficacy of the treatment received by the combination group was much higher than that of the control group(P<0.05).Besides,after treatment,the cardiac function indicators such as left ventricular ejection fraction(LVEF),left ventricular end-systolic volume(LVESV),and cardiac index(CI)of the patients in the combination group were significantly better than those of the reference group(P<0.05).Furthermore,the high-sensitivity C-reactive protein(Hs-CRP),N-terminal prohormone of brain natriuretic peptide(NT-proBNP),adiponectin(APN),and other related test indicators of the patients in the combination group were significantly better than those of the reference group(P<0.05).Conclusion:Low-dose Betaloc combined with amiodarone has a noticeable effect in treating ventricular arrhythmia and deserves to be widely promoted.

Strided Self-Supervised Low-Dose CT Denoising for Lung Nodule Classification

Lung nodule classification based on low-dose computed tomography(LDCT)images has attracted major attention thanks to the reduced radiation dose and its potential for early diagnosis of lung cancer from LDCT-based lung cancer screening.However,LDCT images suffer from severe noise,largely influencing the performance of lung nodule classification.Current methods combining denoising and classification tasks typically require the corresponding normal-dose CT(NDCT)images as the supervision for the denoising task,which is impractical in the context of clinical diagnosis using LDCT.To jointly train these two tasks in a unified framework without the NDCT images,this paper introduces a novel self-supervised method,termed strided Noise2Neighbors or SN2N,for blind medical image denoising and lung nodule classification,where the supervision is generated from noisy input images.More specifically,the proposed SN2N can construct the supervision infor-mation from its neighbors for LDCT denoising,which does not need NDCT images anymore.The proposed SN2N method enables joint training of LDCT denoising and lung nodule classification tasks by using self-supervised loss for denoising and cross-entropy loss for classification.Extensively experimental results on the Mayo LDCT dataset demonstrate that our SN2N achieves competitive performance compared with the supervised learning methods that have paired NDCT images as supervision.Moreover,our results on the LIDC-IDRI dataset show that the joint training of LDCT denoising and lung nodule classification significantly improves the performance of LDCT-based lung nodule classification.

新型^(18)F-FES PET/CT无创功能性诊断乳腺癌迟发性肺转移致霍纳综合征一例

激素受体阳性、人表皮生长因子受体2型阴性(HR^(+)/HER2^(-))乳腺癌是最常见的乳腺癌分子亚型,可表现为术后10~15年以上的迟发性复发,且其肺转移病灶需与原发性肺癌相鉴别。本文报道1例HR^(+)/HER2^(-)乳腺癌术后16年迟发性肺转移致霍纳综合征患者,采用^(18)F-FDG PET/CT难以判断肿瘤来源,穿刺活检风险高,经北京协和医院新型^(18)F-FES PET/CT无创功能性诊断为乳腺癌肺上叶雌激素受体(estrogen receptor,ER)阳性转移,给予CDK4/6抑制剂+芳香化酶抑制剂内分泌解救治疗后获得缓解。本文总结该患者的临床表现及诊治经过,为新型^(18)F-FES PET/CT评估乳腺癌患者转移灶的ER表达情况及指导后续个体化诊疗提供借鉴。

CT血管成像对ACI患者颈动脉狭窄程度及侧支循环的价值研究

目的分析、探究CT血管成像技术在ACI患者颈动脉狭窄、侧支循环等病情诊断方面的成效。方法对我院2021.3-2022.3月期间收治的100例急性脑梗死(ACI)患者一般病理资料进行回顾性分析,以数字减影血管造影(DSA)结果为诊断金标准,对CT血管成像技术(CTA)的诊断价值进行分析,以临床出具的数字减影血管造影(DSA)结果为金标准,分析CT血管成像技术(CTA)在临床上的诊断价值,评估此技术在临床诊断中的效能。结果与临床金标准相比,CTA诊断技术具有较高的临床评估价值[Kappa>0.8~1.0,曲线下面积(AUC)>0.9,P<0.01];CTA诊断技术在评估颈动脉狭窄程度等方面与临床金标准具有一定的一致性[Kappa>0.6~0.8,曲线下面积(AUC)>0.7~0.9,P<0.01];而在评估侧支循环临床诊断中,CTA诊断技术与临床金标准具有一致性,具有较高的评估价值[Kappa>0.8~1.0,曲线下面积(AUC)>0.9,P<0.01]。结论以临床“金标准”的诊断结果为依据分析,CTA诊断技术能够对ACI患者出现病变的血管形态及侧支循环状态等进行全面的评估,CTA诊断结果可为治疗工作提供准确性相对较高且客观的医学依据,确实是评估ACI患者颈动脉狭窄程度、侧支循环状态的可靠办法;而与DSA技术相比,CTA与之具有较高的一致性,说明在病情发作早期为ACI患者实施CTA检查可获悉颈动脉的狭窄及侧支循环状态,有利于改善患者群体的预后。

CT灌注成像参数对急性脑梗死侧支循环的评估价值及与术后近期预后的相关性

目的探讨CT灌注成像(CTPI)参数对急性脑梗死(ACI)侧支循环的评估价值及与术后近期预后的相关性。方法选取我院2022年1月-2023年2月收治的106例ACI患者,以数字血管造影(DSA)作为诊断“金标准”,将其分有侧支循环组(46例)与无侧支循环组(60例)。两组患者均进行CTPI检查,对比两组受试者CTPI参数[脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)及达峰时间(TTP)],采用受试者工作特征(ROC)曲线分析CTPI参数对ACI侧支循环的预测价值;比较CTPI参数评估急性缺血性脑梗死侧支循环与DSA检查的一致性;采用Pearson相关性分析ACI患者的CTPI参数与美国国立卫生研究院卒中量表(NIHSS)、改良Ranking量表(mRS)评分的相关性。结果有侧支循环组CBV、CBF均高于无侧支循环组(P<0.05),MTT、TTP均低于无侧支循环组(P<0.05)。ROC曲线分析显示,CBV、CBF、MTT、TTP及联合检测对ACI侧支循环均有预测效能(P<0.05),其AUC分别为0.793、0.705、0.841、0.669、0.879,单独检测中MTT效能最高,但仍低于联合检测效能。CTPI参数联合检查对ACI侧支循环的诊断灵敏性为84.78%、特异性为90.00%、准确率为87.74%、阳性预测值为86.67%、阴性预测值为88.52%、Kappa值为0.750。有侧支循环组NIHSS、mRS评分均低于无侧支循环组(P<0.05);Pearson相关分析发现,CBV、CBF与NIHSS、mRS评分呈负相关(P<0.05),MTT、TTP与NIHSS、mRS评分呈正相关(P<0.05)。结论ACI有侧支循环患者的CBV、CBF均较无侧支循环患者高,MTT、TTP均较无侧支循环患者低,CTPI参数用于评估ACI侧支循环具有较高的诊断效能,且有侧支循环患者近期预后较好,同时CBV、CBF、MTT、TTP与ACI患者近期预后均存在相关性,可通过检测CBV、CBF、MTT、TTP预测患者近期预后。

低剂量CT结合SHOX2、RASSF1A甲基化在肺癌早期预警中的应用

目的探讨低剂量CT结合Ras相关区域家族蛋白1A(RASSF1A)、矮小同源盒基因2(SHOX2)甲基化在肺癌早期预测中的应用价值。方法选取2021年1月~2023年1月我院90例拟行肺结节手术患者,根据手术病理学分为肺良性结节组和肺癌组。2组均于术前行低剂量CT检查、SHOX2、RASSF1A甲基化检测,采用Kappa指数分析上述检查结果与手术病理学一致性,分析低剂量CT、SHOX2、RASSF1A甲基化与血清肿瘤标志物[癌胚抗原(CEA)、神经元特异性烯醇化酶(NSE)、鳞状细胞癌抗原(SCC-Ag)、细胞角蛋白19片段(CYFRA21)]对肺癌诊断效能,采用Spearman低剂量CT检查、SHOX2、RASSF1A甲基化与临床病理特征相关性。结果低剂量CT、SHOX2、RASSF1甲基化及三者联合分别确定40例、43例、46例、58例肺癌,三者联合与手术病理学诊断肺癌效能一致性Kappa值为0.951;三者联合诊断肺癌敏感度96.67%、准确度97.78%均高于三者单一诊断效能(P<0.05);肺癌患者血清CEA、SCC、NSE、CYFRA21水平均高于肺良性结节患者(P<0.05);低剂量CT联合SHOX2、RASSF1甲基化诊断肺癌效能的AUC为0.983,近似于四种血清肿瘤标志物诊断肺癌效能的AUC 0.933;不同肿瘤直径、临床分期、组织学分化肺癌患者低剂量CT检出率及SHOX2、RASSF1A甲基化阳性率比较差异有统计学意义(P<0.05);肺癌患者低剂量CT检出率、SHOX2及RASSF1A甲基化阳性率与肿瘤直径、临床分期呈正相关,与组织学分化呈负相关(P<0.05)。结论低剂量CT联合SHOX2及RASSF1A甲基化可用于肺癌早期预警中,临床可通过其进行早期诊断、评估病情进展程度,以针对性展开后续治疗,改善预后。

双能量CT非线性融合和噪声优化的虚拟单能量图像技术在喉鳞状细胞癌中的应用

目的:探讨双能量CT线性融合图像(linear blending imaging,LBI)、非线性融合图像(nonlinear blending image,NBI)和噪声优化的虚拟单能量图像(noise-optimized virtual monoenergetic image,VMI+)技术在喉鳞状细胞癌中的应用价值。方法:回顾性分析2019年6月至2022年3月61例经病理证实为喉鳞状细胞癌患者的双能量CT资料。双能量图像采用LBI[融合系数为1(80 kV)和0.6(M0.6)]、NBI和VMI+(40 keV、55 keV)技术重建。比较5组图像的客观图像质量[对比噪声比(contrast-tonoise ratio,CNR)、肿瘤CT值、噪声]和主观图像质量(肿瘤边界评分和整体图像质量评分)。结果:40 keV的CNR、肿瘤CT值和肿瘤边界评分均明显高于80 kV、M0.6、NBI和55 keV,差异均有统计学意义(均P<0.05)。NBI的整体图像质量评分明显高于80 kV、M0.6、40 keV和55 keV,差异均有统计学意义(均P<0.05)。NBI的噪声明显低于80 kV、40 keV和55 keV,差异均有统计学意义(均P<0.05)。结论:在喉鳞状细胞癌的双能量CT中,采用VMI+技术(40 keV)能提供更好的CNR、肿瘤CT值和肿瘤边界,采用NBI技术能提供更低的噪声和更好的整体图像质量。

乳腺癌患者腋窝淋巴结转移的危险因素及行X线摄影与CT检查的诊断效能分析

目的:探讨乳腺癌患者腋窝淋巴结转移的危险因素及X线与CT检查的诊断效能比较。方法:选取2021年1月至2023年5月在我院治疗的乳腺癌患者112例,分析发生和未发生腋窝淋巴结转移患者临床资料差异;同时分析X线、CT检查诊断腋窝淋巴结转移的价值。结果:112例患者中,腋窝淋巴结转移患者32例,腋窝淋巴结转移率为28.57%;发生腋窝淋巴结转移患者组织低分化比例、组织类型为浸润性癌比例、有脉管浸润比例、肿瘤直径≥5cm比例、组织Ki-67表达≥14%比例分别为68.75%、90.63%、28.13%、31.25%和84.38%,明显高于未发生腋窝淋巴结转移患者(P<0.05);Logistic回归分析显示:分化程度、病灶组织类型、脉管浸润、Ki-67表达是乳腺癌患者发生腋窝淋巴结转移的影响因素(P<0.05);X线诊断腋窝淋巴结转移与病理结果一致性Kappa值为0.500,P<0.05,一致性较差;CT诊断腋窝淋巴结转移与病理结果一致性Kappa值为0.825,P<0.05,一致性较好;CT诊断腋窝淋巴结转移的准确性、灵敏性和阴性预测值分别为92.86%、87.50%和95.00%,明显高于X线检查(P<0.05)。结论:乳腺癌患者腋窝淋巴结转移受分化程度、病灶组织类型、脉管浸润、Ki-67表达的影响;相较于X线,CT诊断腋窝淋巴结转移的价值较高。

基于高维PDE投影恢复的低剂量CT重建方法

目的提出一种基于高维偏微分方程(PDE)投影恢复的低剂量CT重建方法。方法先将原始的投影数据映射到高维空间中,构造投影数据的高维表示,通过移动高维空间中的点来对高维表示进行更新,再使用偏微分方程对投影数据进行滤波,最后将恢复后的数据使用FBP算法重建出最终CT图像。结果在Shepp-Logan体模实验中,与FBP,PWLS-QM和TGV-WLS方法相比,新方法在相对均方根误差指标上分别降低了68.87%、50.15%和27.36%,结构相似性上分别提高了23.50%,8.83%和1.62%,特征相似性上分别提高了17.30%、2.71%和2.82%。在腹部临床数据实验中,与FBP,PWLS-QM和TGV-WLS方法相比,新方法在相对均方根误差中分别降低了42.09%、31.04%和21.93%,结构相似性上分别提高了18.33%、13.45%和4.63%,特征相似性上分别提高了3.13%、1.46%和1.10%。结论本研究提出的新方法在有效去除低剂量CT图像中的条形伪影和噪声的同时,可以保持图像的空间分辨率。

一种新的术中X线与术前CT图像配准方法

目的本研究旨在配准胸主动脉血管内修复术(thoracic endovascular aortic repair,TEVAR)术中X线与术前CT图像,为TEVAR支架植入提供精确安全的导航。然而,现有配准算法存在无法有效弥合投影CT图像生成的数字重建影像(digitally reconstructed radiography,DRR)与X线图像之间的域间差异和难以获得图像分割标签的问题。因此,需要提出新的方法来改善这一问题。方法本文提出了一种新的配准框架,该框架结合了基于生成对抗网络(generative adversarial network,GAN)的域自适应网络和基于Transformer的配准网络。基于GAN的域自适应网络将X线图像的风格迁移到DRR图像上,使两者在图像风格上更接近。基于Transformer的配准网络采用CNN与跨模态变换器(cross-modality transformer,CMT)相结合的模式,直接配准X线与CT图像,无需进行图像分割。结果本文在208对标定的TEVAR术中X线与CT图像对上对新的配准方法进行了验证。与其他域适应方法相比,本文所采用的CycleGAN网络作为风格转换模块,有效减小了DRR图像与X线图像之间的域间差异。消融实验结果进一步证实,配准网络中的全局局部感知模块(global-local perception module,GLPM)对提高配准精度具有明显作用,而空间缩减(spatial reduction,SR)则有效缩短了配准时间。通过对比现有方法和本文方法在真实患者X线与CT图像对上的配准效果,本文的方法在配准精度和成功率方面均表现出最佳性能。结论本文提出的新的X线与CT图像配准方法有效克服了现有方法存在的域间差异以及难以获得分割标签的问题。

一种改进的全变分降噪算法在低剂量工业CT重建图像中的应用

针对低剂量CT重建中的噪声抑制问题,文章将全变分降噪模型应用到CT重建的图像投影域,并介绍了ROF模型及能量泛函的建立,以及在低剂量CT图像处理中的应用。提出一种改进的ROF模型的实现方法。首先,利用梯度下降算法对投影图进行迭低降噪处理。其次,使用滤波反投影算法对工业CT图像进行重建。最后,通过CUDA并行运算实现了整个改进算法的过程,提高了算法的运行时间。通过模拟噪声和锂电池快速在线工业CT设备图像处理结果证明:所提出的方法能有效降低重建图像的噪声,提高图像峰值信噪比。

^(99m)TcO4-SPECT/CT甲状腺核素显像联合超声及TSH对甲状腺结节性质的诊断价值

目的通过高锝酸钠-单光子发射计算机断层显像/电子计算机X射线断层扫描技术(^(99m)TcO4-SPECT/CT)核素显像提供甲状腺结节功能状态、结节解剖特点以及超声检查联合血清促甲状腺激素(TSH)水平进一步鉴别诊断甲状腺结节的良恶性,客观评价甲状腺结节的良恶性情况,对甲状腺结节的良恶性做出早期诊断。方法对因甲状腺结节同时行^(99m)TcO4-SPECT/CT甲状腺核素显像、甲状腺B超及TSH水平检查的患者共80例(92个结节)进行回顾性分析,对比不同方法及联合检查对甲状腺结节的诊断效能。结果92个结节中良性74个,恶性18个;^(99m)TcO4-SPECT/CT甲状腺显像与超声检查比较灵敏度(77.8%)高,特异度(70.2%)及准确度(71.7%)低,假阳性率(29.7%)高,假阴性率(22.2%)低,两者之间灵敏度、特异度、准确度、假阳性率、假阴性率差异均具有统计学意义(P<0.05);两者准确度比较差异无统计学意义(P>0.05)。^(99)mTcO4-SPECT/CT甲状腺显像与超声检查比较灵敏度高,特异性及准确度低,假阳性率高,假阴性率低,两者之间灵敏度、特异度、准确度、假阳性率、假阴性率差异均具有统计学意义(P<0.05);两者准确度比较差异无统计学意义(P>0.05);^(99m)TcO4-SPECT/CT甲状腺显像与超声检查联合较单独核素、单独超声检查灵敏度(88.9%)、特异度(87.8%)、准确度(81.5%)高,假阳性率(12.1%)、假阴性率(11.1%)低;联合检查与单独核素特异度、准确度、假阳性率比较差异有统计学意义(P<0.05),灵敏度与假阴性率比较差异无统计学意义(P>0.05);联合检查与单独超声灵敏度、准确度、假阴性率比较差异有统计学意义(P<0.05);特异度与假阳性率比较差异无统计学意义(P>0.05)。结论超声可以作为甲状腺结节的首选检查方法,其特异性高,但灵敏度低。^(99m)TcO4-SPECT/CT甲状腺显像在提供功能和代谢信息的同时,能提供解剖信息;而血清TSH水平则可为甲状腺结节的良恶性鉴别提供重要的参考依据,尤其对于核素冷结节且超声实性结节的患者,更应参考其TSH水平,将三者结合起来判断甲状腺结节的性质,为临床提供恰当的治疗方案,这具有重要意义。