自适应统计迭代重建算法在儿童头部CT扫描中的应用

目的 探讨自适应统计迭代重建(ASiR)算法在儿童头部CT扫描中的应用价值。方法 对1个水模进行CT扫描,管电压100 kV,管电流分别为200、180、160、140、120和100 mA,ASiR比例分别设置为0、10%、20%、30%、40%、50%,采用FBP和ASiR迭代重建两种重建算法进行图像重建,比较不同条件下图像CNR、SNR和图像噪声。将80例接受头部CT扫描的患儿分为对照组(n=40)和试验组(n=40)。对照组采用管电压100 kV、管电流200 mA,FBP重建算法进行图像重建;试验组采用管电压100 kV、管电流140 mA,分别采用FBP和ASiR两种重建法进行图像重建;将重建后的图像分别记为试验FBP亚组和试验ASiR亚组;对两组中图像的CNR、SNR、图像噪声、CTDIvol、DLP、ED进行比较。结果 水模研究中,采用ASiR(30%)、管电流140 mA、ASiR算法重建图像的SNR、CNR及空气噪声值与管电流 200 mA、FBP重建图像最为接近。对照组与试验ASiR亚组图像的图像噪声、灰白质CNR和灰质SNR值差异均无统计学意义(P均>0.05);对照组和试验ASiR亚组图像的噪声、灰质SNR、灰白质CNR均优于试验FBP亚组,且差异均有统计学意义(P均<0.001)。结论 采用ASiR重建算法的头部CT扫描,既可降低患儿接受的辐射剂量,又保证了图像质量,具有较高的临床应用价值。     

低管电压迭代重建模型在冠状动脉CTA中的应用

目的 探讨低管电压迭代重建模型（IMR）在冠状动脉CTA中的应用价值。方法 选取30例疑似冠状动脉心脏病患者,均进行前瞻性心电门控心脏256层MSCT扫描。若体质量指数（BMI）≥25 kg/m²,管电压为100 kV;反之,则为80 kV。分别采用滤波反投影（FBP,A组）、高级混合迭代重建（iDose⁴,B组）和IMR（C组）进行重建。分别测量3组图像主动脉根部的CT值、噪声,并计算SNR和CNR。对图像伪影、管腔边缘的锐利度、主观噪声、总体图像质量以及冠状动脉各主干血管图像质量进行主观评分,进行统计学分析。结果 3组图像的噪声、SNR以及CNR差异有统计学意义（P均<0.05）。噪声由大到小依次为A组、B组和C组（P均<0.05）。SNR和CNR由大到小依次为C组、B组和A组（P均<0.05）。C组噪声、血管边缘锐利度、总体图像质量、冠状动脉各主干血管主观评分显著高于A组和B组（P均<0.05）。B组图像伪影评分显著高于A组和C组（P均<0.05）,且A组与C组图像伪影评分差异无统计学意义（P>0.05）。结论 IMR可显著降低冠状动脉血管成像的图像噪声,提高图像SNR和CNR。     

自动协议选取能谱联合自适应迭代计算法重建技术降低腹部增强及血管成像辐射剂量及对比剂剂量的可行性

目的 探讨利用自动协议选取能谱（ASIS）扫描模式联合自适应迭代算法重建（ASiR）技术降低腹部增强及血管成像辐射剂量及对比剂剂量的可行性。方法 将64例接受腹部增强患者随机分为两组：试验组32例,采用ASIS扫描模式,应用30% ASiR和50% ASiR重建算法;对照组32例,采用120 kVp管电压,FBP重建。比较两组扫描方法辐射剂量及对比剂剂量;比较70 keV+30% ASiR图像与对照组动脉期及门静脉期肝脏及胰腺噪声、竖脊肌噪声（SMN）、肝脏CNR、胰腺CNR;对55 keV+50% ASiR图像与对照组动脉期腹主动脉及各主要分支血管CNR及门静脉期门静脉CNR以及血管图像主观评分进行统计学分析。结果 试验组动脉期及门静脉期的CTDIvol、DLP较对照组下降23.68%、23.57%和25.59%、18.45%,对比剂注射总量试验组较对照组减少16.86%。70 keV+30% ASiR动脉期及门静脉期肝脏、胰腺和竖脊肌的噪声均低于对照组（P均<0.05）。试验组55 keV+50% ASiR动脉期腹主动脉、肠系膜上动脉、腹腔干的CNR均高于对照组（P均<0.05）;静脉期门静脉的CNR和血管评分与对照组比较差异无统计学意义（P>0.05）。结论 采用ASIS扫描模式联合ASiR技术,70 keV+30% ASiR及55 keV+50% ASiR图像显示腹部脏器及腹部血管图像质量均优于传统120 kVp扫描模式的图像质量,且降低了辐射剂量及对比剂剂量。     

SAFAIR联合双能量单能谱及非线性优化对比技术提高颈根部图像质量的应用

目的 探讨原始数据迭代重建（SAFIRE）-3联合双能CT单能谱或优化对比技术在去除颈根部伪影、提高图像质量中的应用价值。方法 选择CT双能量增强扫描颈根部有明显伪影的30例患者图像,均采用线性融合SAFAIR-3重建、获得A组图像（SAFAIR-3重建组）,之后加行单能谱分析、获得B组图像（重建+单能谱组）,或加行双能量非线性优化对比处理、获得C组图像（重建+优化对比组）。分别对A、B、C组图像SD、SNR、CNR及图像质量对比分析。结果 A、B、C组伪影区SD、SNR及CNR差异有统计学意义（P<0.05）。B、C组伪影区SNR、CNR高于A组,噪声低于A组（P均<0.05）。B组与C组的SD、SNR及CNR比较差异无统计学意义（P均>0.05）。A、B、C组图像主观评分差异有统计学意义（P<0.05）,A组3分及以上的图像少于B组及C组（P均<0.05）;B组与C组图像主观评分差异无统计学意义（P>0.05）。结论 采用SAFIRE技术联合单能谱或非线性优化对比技术可减轻颈根部硬化伪影、提高颈根部图像质量。单能谱与优化对比技术在提高颈根部图像质量方面无差异。     

低管电压结合迭代重建技术配合不同对比剂注射方案在冠状动脉CTA成像中的可行性研究

目的 探讨迭代重建技术（IDose⁴）在降低管电压配合不同对比剂碘流率注射方案下行冠状动脉CT血管成像（CCTA）的可行性。方法 对10只实验猪分别重复9次CCTA扫描[管电压分别为120 kV（A₁）、100 kV（A₂）、80 kV（A₃）,对比剂碘流率分别约为1300 mgI/s（B₁）、1000 mgI/s（B₂）及750 mgI/s（B₃）,两两组合成9组方案];对原始图像分别采用滤波反投影法（FBP）及IDose⁴重建,将A₁B₁+FBP重建设为对照组。比较各组图像的主、客观指标。结果 在相同条件下,IDose⁴重建较FBP重建显著降低图像噪声、提高SNR及CNR（P均<0.001）。随管电压及碘流率的降低,图像噪声增大,SNR、CNR降低。采用IDose⁴重建,除A₃B₁、A₃B₂、A₃B₃组噪声仍明显增加外（P均<0.05）,其余各组噪声、SNR、CNR均与对照组无统计学差异（P均>0.05）。采用FBP重建,A₃B₁、A₃B₂、A₃B₃组及A₂B₃组冠状动脉远段可诊断率较对照组明显减低（P均<0.05）,而经IDose⁴重建后,除A₃B₃组冠状动脉远段可诊断率仍明显低于对照组（P=0.015）外,余各组均明显改善,与对照组无统计学差异（P均>0.05）。结论 采用IDose⁴重建结合低管电压及低碘流率行CCTA是可行的。     

超低剂量下不同迭代重建技术在肺动脉成像中的优化

目的 探讨不同迭代重建技术在超低剂量肺动脉成像中的应用价值。方法 对30例临床疑似肺动脉栓塞患者行CT肺动脉成像,扫描采用80 kV管电压并开启自动管电流调制技术,分别采用滤波反投影法(FBP)、iDOSE⁴、迭代模型重建(IMR)重建图像。采用5分制评价肺动脉主干及其分支的图像质量,测量计算图像噪声值、SNR、CNR,记录CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)、计算有效剂量(ED)。比较不同重建技术图像噪声、SNR、CNR及主观图像质量。结果 30例患者的平均体质量指数(BMI)为(25.12±2.48)kg/m²;平均CTDIvol为(0.78±0.28)mGy;平均DLP为(30.46±11.34)mGy·cm,平均ED为(0.43±0.16)mSv。IMR、iDOSE⁴、FBP图像噪声依次增高(P<0.05),SNR、CNR依次降低(P<0.05),CT值差异无统计学意义(P>0.05)。IMR、iDOSE⁴图像的主观评分显著高于FBP(P<0.05);IMR、iDOSE⁴图像可诊断率高于FBP(P<0.05),IMR图像优良率高于iDOSE⁴(P<0.05)。结论 采用80 kV联合IMR可保证肺动脉成像较高的图像质量,同时大大降低患者辐射剂量。     

全模型迭代重建算法评价125I粒子植入术后CT图像

目的 探讨全模型迭代重建（IMR）算法评价¹²⁵I粒子植入术后图像的应用价值。方法 收集接受¹²⁵I粒子植入术及术后CT随访的16例腹部肿瘤患者,对扫描原始数据分别以滤波反投影法（FBP）、IMR和高级重建迭代（iDose⁴）算法进行重建,比较3种重建方法图像的噪声、伪影指数（AI）、CNR和主观评分。结果 FBP重建图像的噪声、CNR及AI分别为（58.65±4.03） HU、1.09±0.43和51.60±9.23,iDose⁴图像分别为（48.38±5.34） HU、1.29±0.48和43.77±4.91,IMR图像分别为（41.46±3.44） HU、1.58±0.56和38.51±4.64,3种重建方法图像的噪声、CNR及AI两两比较差异均有统计学意义（P均<0.05）。IMR图像的主观图像质量评分显著高于FBP和iDose⁴算法图像（调整后P<0.001,P=0.011）。结论 IMR算法获得的图像质量较高,可有效减少¹²⁵I粒子伪影,为¹²⁵I粒子植入术后随访与疗效评估提供了更佳方法。     

基于深度学习的像素闪烁算法对高体质量指数患者低剂量腹部CT平扫图像质量的影响

目的 探讨基于深度学习的像素闪烁（PS）算法对体质量指数（BMI）≥ 25 kg/m²患者低剂量腹部CT平扫图像质量的影响。方法 选取59例接受腹部CT检查、BMI ≥ 25 kg/m²的患者,根据管电压分为A组（100 kVp,n=30）和B组（120 kVp,n=29）。根据不同重建算法和处理方式,将A组分为A1亚组（FBP）、A2亚组（FBP+PS）、A3亚组（50% ASiR-V）和A4亚组（50% ASiR-V+PS）;将B组分为B1亚组（FBP）和B2亚组（50% ASiR-V）。测量2组肝右叶、右侧竖脊肌CT值及SD值,计算肝脏SNR、CNR及容积CT剂量指数（CTDI_vol）,评价2名观察者间所测数值的一致性。结果 2名观察者所测数据的一致性良好（ICC值均> 0.80）。A组各亚组间肝脏及竖脊肌CT值差异无统计学意义（P > 0.05）;肝脏及竖脊肌SD值、肝脏SNR值差异有统计学意义（P均< 0.001）;两两比较SD_A4 < SD_A2 < SD_A3 < SD_A1,SNR_A4 > SNR_A2 > SNR_A3 > SNR_A1;A1与A3亚组间CNR值差异无统计学意义（P=0.078）,其余亚组间两两比较CNR_A4 > CNR_A2 > CNR_A3或CNR_A1（P均< 0.001）。A2亚组肝脏SD值较B1亚组、A4亚组较B2亚组明显降低,SNR及CNR值明显增高（P均< 0.001）。A组CTDI_vol明显低于B组（P均< 0.001）。结论 采用基于深度学习的PS算法可改善高BMI患者低剂量腹部CT平扫图像质量。     

能谱CT的SSA技术在前瞻性心电门控冠状动脉成像中的应用

目的 探讨能谱CT snapshot assist（SSA）技术在前瞻性心电门控冠状动脉成像中降低患者辐射剂量中的应用价值。方法 收集行前瞻性心电门控冠状动脉成像的患者59例,分为SSA组及常规组,SSA组采用SSA技术扫描。比较SSA组与常规组图像质量和剂量长度乘积（DLP）、有效辐射剂量（ED）的差异。结果 2组图像质量评分差异无统计学意义（χ²=2.362,P=0.307）,2组冠状动脉CTA左主干起始处的主动脉根部平均CT值差异无统计学意义（Z=-0.061,P=0.951）;噪声、CNR、SNR差异均有统计学意义（P均<0.05）。SSA组DLP为（135.44±37.41）mGy·cm,ED为（1.89±0.52）mSv,常规组DLP为（275.57±36.59）mGy·cm,ED为（3.85±0.51）mSv,2组差异均有统计学意义（t=14.504,P均<0.001）,SSA组较常规组有效辐射剂量降低约50.85%。结论 能谱CT的SSA技术在前瞻性心电门控扫描冠状动脉成像中可以降低患者的有效辐射剂量,具有较高的临床应用价值。     

FBP、iDose4和IMR重建算法对低剂量双下肢CTA图像质量的影响

目的 探讨滤波反投影（FBP）、混合迭代重建（iDose⁴）和基于模型的迭代重建（IMR）技术对低剂量双下肢CTA图像质量的影响。方法 对56例成年患者行双下肢CTA扫描,分别用FBP、iDose⁴和IMR方法重建,测量下肢各段血管（腹主动脉分叉处、髂总动脉分叉处、股动脉近端、股动脉中段和腘动脉近端）的CT值、图像噪声及对比噪声比（CNR）,并采用4分法对3组图像质量分别进行主观评分。结果 FBP、iDose⁴和IMR重建图像的下肢各段血管平均CT值分别为（511.07±195.05）HU、（492.63±178.74）HU、（487.63±197.20）HU,三者间差异无统计学意义（F=1.175,P>0.05）。图像噪声分别为（76.24±20.85）HU、（39.16±11.75）HU、（13.09±2.55）HU,三者间差异有统计学意义（F=1 460.000,P<0.05）。CNR分别为6.35±3.14、12.97±5.10、33.83±15.85,三者间差异有统计学意义（F=646.122,P<0.05）。图像质量主观评分IMR（3.75±0.46）、FBP（1.39±0.51）、iDose⁴（2.61±0.81）差异有统计学意义（χ²=476.79,P<0.05）,膝关节以上、下段动脉可诊断率IMR（98.66%）明显高于FBP（1.34%）、iDose⁴（56.70%）,差异均有统计学意义（χ²=427.9,P<0.05）。结论 行低辐射剂量双下肢CTA扫描时,相比FBP和iDose⁴,IMR可以显著降低图像噪声,提高图像质量,且能满足诊断要求。     

Tissue harmonic imaging, frequency compound imaging, and conventional imaging: use and benefit in breast sonography.

OBJECTIVE: The purpose of this study was to evaluate different sonographic settings (tissue harmonic, frequency compounding, and conventional imaging) and to determine which setting optimizes breast lesion detection and lesion characterization. METHODS: Four hundred thirteen consecutive breast lesions (249 benign and 164 malignant) were evaluated by sonography using 4 different modes (conventional imaging at 14 MHz, tissue harmonic imaging at 14 MHz [THI], and frequency compound imaging at 10 MHz [CI10] and 14 MHz [CI14]). The images were reviewed by consensus by 2 breast radiologists. For each image, the lesion was graded for conspicuity, mass margin assessment, echo texture assessment, overall image quality, and posterior acoustic features. RESULTS: For lesion conspicuity, THI and CI14 were better than conventional imaging (P < .01) and CI10 (P < .01) particularly against a fatty background (P < .01 for THI versus conventional for a fatty background versus P = .13 for a dense background). Frequency compound imaging at 10 MHz performed the best in echo texture assessment (P < .01), as well as overall image quality (P < .01). For margin assessment, CI10 performed better for deep and large (> or =1.5-cm) lesions, whereas CI14 performed better for small (<1.5-cm) and superficial lesions. Finally, THI and CI14 increased posterior shadowing (P < .01) and posterior enhancement (P < .01). CONCLUSIONS: The standard breast examination incorporates 2 distinct processes, lesion detection and lesion characterization. With respect to detection, THI is useful, especially in fatty breasts. With respect to characterization, compound imaging improves lesion echo texture assessment. No single setting in isolation can provide the necessary optimized information for both of these tasks. As such, a combination approach is best.     

Contribution of tissue harmonic imaging and frequency compound imaging in interventional breast sonography.

OBJECTIVE: The purpose of this study was to retrospectively compare conventional imaging, frequency compound imaging (CI), and tissue harmonic imaging (THI) in interventional breast sonography. METHODS: Institutional Review Board approval and patient informed consent were not required. The authors reviewed 104 sonographically guided breast procedures in 83 patients. For each biopsy, 4 images obtained with conventional imaging, frequency CI at 10 and 14 MHz (CI10 and CI14), and THI were graded independently by 2 radiologists for lesion conspicuity, needle conspicuity, lesion and needle conspicuity, and overall image quality. Frequency CI at 10 MHz, CI14, and THI were compared with conventional imaging. Different clinical scenarios (fatty versus glandular background, fine needle versus core needle, and oblique versus horizontal needle direction) were evaluated. RESULTS: Statistical analysis showed that for overall image quality, CI10 was the best setting (odds ratios [OR], 3.67 and 7.48). For lesion conspicuity, CI14 (OR, 3.55) and THI (OR, 1.77) improved lesion visibility in a fatty background, whereas THI (OR, 0.26) was very limited in a glandular background. For needle conspicuity, no setting was better than conventional, whereas THI was the least valuable setting (OR, 0.011 and 0.049). For lesion and needle conspicuity, CI10 showed significantly better results than conventional for a dense background (P = .0268 and .4028; OR, 2.435 and 1.383) with 1 reviewer, whereas THI was the least valuable setting (OR, 0.014 and 0.042). CONCLUSIONS: Conventional imaging provided the best assessment of lesion and needle conspicuity. Frequency compounding is a useful setting for dense breast and for fine-needle aspiration. Tissue harmonic imaging has a role in the visualization of a lesion against a fatty background but is of limited value in needle visualization.     

Gallbladder adenomyomatosis: imaging findings

In this pictorial essay, we describe the imaging findings of adenomyomatosis of the gallbladder and emphasize high-resolution ultrasound and magnetic resonance cholangiopancreatography in its diagnosis.     

MR imaging of intrahepatic cholangiocarcinoma

Background: The purpose of this study was to determine the magnetic resonance (MR) features of intrahepatic cholangiocarcinoma. Methods: MR imaging studies of seven cases of pathologically proven intrahepatic cholangiocarcinoma were retrospectively reviewed. Results: On MR images the tumors presented as a single mass (N = 5) or multiple nodules (N = 2), as welldelineated (N = 5) or ill-defined (N = 2), and as non-encapsulated (N = 7). Mean tumor diameter ranged from 6–14 cm (mean, 10 cm). On T1-weighted (TR/TE = 400–600/10–17 msec) images, the tumors were hypointense compared to the liver. The five tumors studied with dynamic MR imaging showed progressive centripetal filling-in after intravenous administration of a gadolinium chelate. On T2-weighted (TR/TE = 2000–2500/80–100 msec) images, all tumors were hyperintense compared to the liver; five were markedly hyperintense and two moderately hyperintense. Vascular encasement, bile duct dilatation within the tumor, and central scar were depicted on MR images in four, three, and two tumors respectively. Conclusion: The typical MR appearance of intrahepatic cholangiocarcinoma is a large well-delineated nonencapsulated tumor associated with intrahepatic venous encasement.     

MR imaging of adrenal lymphoma

A case of lymphoma of the adrenal glands is presented. Both computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated large bilateral adrenal masses with no other associated abdominal abnormalities. MR was better able to demonstrate inferior vena caval patency than CT, and effectively exclude pheochromocytoma as a differential diagnostic consideration due to signal characteristics of the masses.     

Dynamic imaging for swallowing reeducation

Dynamic imaging is frequently indispensable for the rational treatment of disordered swallowing. The effects of test feeding techniques, bolus modification, patient positioning, and respiratory maneuvers are all best documented by visualizing and recording the swallowing of radiopacified boluses. What is seen becomes the basis of patients' reeducation in swallowing. Greatest effectiveness results when the radiologic examination is shared with those responsible for the patient's rehabilitation in swallowing.     

二维斑点追踪成像与组织多普勒评价早期系统性硬皮病患者右心室功能

目的 采用超声二维斑点追踪成像(STI)及组织多普勒(TDI)评价早期硬皮病(SSc)患者右心室功能.方法 采用STI及TDI评价35例SSc患者(SSc组)及40名正常人(NOR组)的右心室游离壁基底段、中间段及心尖段应变.结果 STI与TDI均显示SSc组右心室游离壁基底段、中间段及心尖段应变均低于NOR组,差异具有统计学意义(P＜0.05);STI与TDI所测应变显著相关(P＜0.01).结论 SSc患者右心室功能减低.STI及TDI均可评价SSc患者右心室功能.     

Magnetic resonance imaging of bladder hemangioma

An 18-year-old woman with a bladder hemangioma is described. The tumor had a low signal intensity with multilocular pattern on T1-weighted magnetic resonance (MR) images and high signal intensity on T2-weighted MR images. MR images were useful in evaluating tumor character and its extent.     

MR imaging of ulcerative colitis

High-resolution magnetic resonance imaging (MRI) was used to study 16 resected rectosigmoid specimens of patients treated with total colectomy for severe ulcerative colitis (UC). Six normal colon specimens were also studied as a control group. Moreover, a parallel study of the pelvis of 24 patients with a proven diagnosis of UC was performed with the same MR system. Both in vitro and in vivo MRI findings [thickening and signal intensity (SI)] of the mural layers were qualitatively evaluated by two radiologists and compared with gross and microscopic aspects. In vitro results showed that MRI was able to identify all layers of the colonic wall. In particular in UC specimens, MRI identified thickening and the peculiar abnormal hyperintensity of the mucosal and submucosal layers on spin-echo (SE) T1-weighted images. In vivo results confirmed the high-signal intensity of the mucosal and submucosal layers. These findings were not observed in the control group in which the superficial layers appeared low in intensity on SE T1 images. Our preliminary experience suggests that MRI should be considered a new imaging modality for detecting UC colonic wall changes.     

核素肾动态显像当日再进行骨显像的可行性

目的 观察肾动态显像当日进行全身骨显像对骨显像图像质量及患者的安全性的影响。方法 选取检查申请中既有肾动态显像又有全身骨显像检查的成年患者53例为观察组,常规接受⁹⁹Tc^m-DTPA肾动态显像检查2 h后,再注射⁹⁹Tc^m-MDP,按骨显像流程接受全身检查;另选取53例仅接受骨显像检查患者为对照组。两组于注射⁹⁹Tc^m-MDP后即刻、30 min、1 h、2 h、4 h、6 h、24 h观察患者不良反应。观察两组患者骨显像图像质量,统计图像质量优良率。测量骨后位像T12、L4、髂嵴、肱骨中段、股骨中段和髂骨上2 cm处软组织的放射计数,计算各部位靶/非靶比值（T/NT）值;对两组数据进行统计学分析。结果 两组患者均无不良反应。观察组和对照组肉眼观察图像质量优良率为90.57%（48/53）、92.45%（49/53）,差异无统计学意义（χ²=0.12,P > 0.05）。两组间T12、L4、肱骨中段、股骨中段T/NT值差异均无统计学意义（P均> 0.05）,髂嵴T/NT值差异有统计学意义（t=3.45,P<0.05）。结论 核素肾动态显像检查同日行全身骨显像检查对图像质量无明显影响。