Diagnostic Accuracy of Split-Bolus Single-Phase Contrast-Enhanced Cone-Beam CT for the Detection of Liver Tumors before Transarterial Chemoembolization

Purpose

To evaluate detectability of hepatocellular carcinoma (HCC) using split-bolus cone-beam CT in intraindividual comparison between cone-beam CT and contrast-enhanced MR imaging.

Low-Tube-Voltage 80-kVp Neck CT: Evaluation of Diagnostic Accuracy and Interobserver Agreement

BACKGROUND AND PURPOSE:Low-tube-voltage acquisition has been shown to facilitate substantial dose savings for neck CT with similar image contrast compared with standard 120-kVp acquisition. However, its potential for the detection of neck pathologies is uncertain. Our aim was to evaluate the effects of low-tube-voltage 80-kV(peak) acquisitions for neck CT on diagnostic accuracy and interobserver agreement.MATERIALS AND METHODS:Three radiologists individually analyzed 80-kVp and linearly blended 120-kVp image series of 170 patients with a variety of pathologies who underwent dual-energy neck CT. Reviewers were unblinded to the clinical indication for CT but were otherwise blinded to any other data or images and were asked to state a final main diagnosis. Findings were compared with medical record charts, CT reports, and pathology results. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each observer. Interobserver agreement was evaluated by using intraclass correlation coefficients.RESULTS:Diagnoses were grouped as squamous cell carcinoma–related (n = 107, presence/absence of primary/recurrent squamous cell carcinoma), lymphoma-related (n = 40, presence/absence of primary/recurrent lymphoma), and benign (n = 23, eg, abscess). Cumulative sensitivity, specificity, positive predictive value, and negative predictive value for 80-kVp and blended 120-kVp images were 94.8%, 93.0%, 95.9%, and 91.1%, respectively. Results were also consistently high for squamous cell carcinoma–related (94.8%/95.3%, 89.1%/89.1%, 94.3%/94.4%, 90.1%/91.0%) and lymphoma-related (95.0%, 100.0%, 100.0%, 95.2%) 80-kVp/120-kVp image series. Global interobserver agreement was almost perfect (intraclass correlation coefficient, 0.82, 0.80; 95% CI, 0.76–0.74, 0.86–0.85). Calculated dose-length product was reduced by 48% with 80-kVp acquisitions compared with the standard 120-kVp scans (135.5 versus 282.2 mGy × cm).CONCLUSIONS:Low-tube-voltage 80-kVp CT of the neck provides sufficient image quality with high diagnostic accuracy in routine clinical practice and has the potential to substantially decrease radiation exposure.

CT is a standard imaging technique in routine clinical practice for detection, staging, and follow-up evaluation of various pathologies of the neck, including squamous cell carcinoma (SCC), cervical lymphoma or lymphadenopathy, and parapharyngeal or retropharyngeal abscess.^1–5 CT examinations contribute a substantial amount of cumulative radiation exposure to patients with cervical pathologies, especially if follow-up CT is required.⁶ Thus, various approaches for dose reduction of CT of the neck, brain, paranasal sinus, and the facial skeleton have been proposed, including reduction of tube current and tube potential, high-pitch acquisition, and application of automated exposure-control software.^7–10 The combination of such techniques with an iterative reconstruction algorithm can also provide similar image quality while substantially reducing exposure to ionizing radiation compared with the standard 120-kVp acquisitions.^11,12Several studies have demonstrated that low-tube-voltage acquisitions at 80 kVp can increase iodine attenuation and image contrast of soft-tissue structures and reduce radiation exposure.^13–15 However, only a few studies have investigated low-tube-voltage acquisition CT techniques for imaging of the neck.^16–18 We hypothesized that an 80-kVp acquisition may provide comparable image quality for evaluation of the neck region. To evaluate the efficacy of this technique in simulated routine clinical practice, we retrospectively assessed the diagnostic accuracy of low-tube-voltage 80-kVp image series from dual-energy neck CT (DECT) for evaluation of a variety of cervical pathologies, and the results were compared with linearly blended images representing a standard 120-kVp acquisition. We also assessed interobserver agreement and calculated the potential radiation dose reduction.     

Accuracy of Nonenhanced CT vs Contrast-Enhanced CT for Diagnosis of Acute Appendicitis in Adults

BackgroundAcute appendicitis is one of the most common causes of acute abdominal pain requiring emergency intervention. It is often difficult for the clinician to make an accurate diagnosis due to nonspecific and overlapping clinical symptoms. Computed tomography (CT) has become the imaging modality of choice for the evaluation of suspected acute appendicitis. The main purpose of our study was to compare nonenhanced CT (NECT) with contrast-enhanced CT (CECT) for the diagnosis of acute appendicitis.Material and MethodsA total of 140 patients were enrolled in the study. Two abdominal radiologists—masked to both the clinical information and the final diagnosis—retrospectively reviewed the computed tomographic findings and made an imaging diagnosis based on (1) NECT only, (2) CECT only, and (3) both NECT and CECT. With the final diagnosis as the reference standard, the accuracy of each CT technique was estimated.ResultsThe respective sensitivity, specificity, and accuracy for NECT, CECT, and NECT + CECT for the diagnosis of acute appendicitis were 80.7%, 86.7%, and 84.3%; 86.0%, 81.9%, and 83.6%; and, 87.7%, 80.7%, and 83.6%. There was no significant difference in the diagnosis of acute appendicitis among the 3 techniques. In order to make a correct diagnosis, the presence of at least 3 imaging findings for NECT or at least 4 for CECT had the best diagnostic accuracy. We also found that 9.25 mm was the optimal cut-off threshold for the detection of patients with acute appendicitis.ConclusionOur study allowed direct comparison between NECT, CECT, and NECT + CECT combined. There was no difference in the ability of each CT technique for diagnosing patients with acute appendicitis. For a patient whom iodinated contrast media is contraindicated or a patient who has an increased risk of severe adverse reaction, we would encourage the use of NECT because it provides comparable diagnostic accuracy without further exposing such patient to the contrast media.     

Impact of Model-Based Iterative Reconstruction on Image Quality of Contrast-Enhanced Neck CT

BACKGROUND AND PURPOSE:Improved image quality is clinically desired for contrast-enhanced CT of the neck. We compared 30% adaptive statistical iterative reconstruction and model-based iterative reconstruction algorithms for the assessment of image quality of contrast-enhanced CT of the neck.MATERIALS AND METHODS:Neck contrast-enhanced CT data from 64 consecutive patients were reconstructed retrospectively by using 30% adaptive statistical iterative reconstruction and model-based iterative reconstruction. Objective image quality was assessed by comparing SNR, contrast-to-noise ratio, and background noise at levels 1 (mandible) and 2 (superior mediastinum). Two independent blinded readers subjectively graded the image quality on a scale of 1–5, (grade 5 = excellent image quality without artifacts and grade 1 = nondiagnostic image quality with significant artifacts). The percentage of agreement and disagreement between the 2 readers was assessed.RESULTS:Compared with 30% adaptive statistical iterative reconstruction, model-based iterative reconstruction significantly improved the SNR and contrast-to-noise ratio at levels 1 and 2. Model-based iterative reconstruction also decreased background noise at level 1 (P = .016), though there was no difference at level 2 (P = .61). Model-based iterative reconstruction was scored higher than 30% adaptive statistical iterative reconstruction by both reviewers at the nasopharynx (P < .001) and oropharynx (P < .001) and for overall image quality (P < .001) and was scored lower at the vocal cords (P < .001) and sternoclavicular junction (P < .001), due to artifacts related to thyroid shielding that were specific for model-based iterative reconstruction.CONCLUSIONS:Model-based iterative reconstruction offers improved subjective and objective image quality as evidenced by a higher SNR and contrast-to-noise ratio and lower background noise within the same dataset for contrast-enhanced neck CT. Model-based iterative reconstruction has the potential to reduce the radiation dose while maintaining the image quality, with a minor downside being prominent artifacts related to thyroid shield use on model-based iterative reconstruction.

Since the introduction of CT for medical imaging in the early 1970s, there has been tremendous advancement in overall image quality with concomitant shortening of requisite scan times. Additional major effort has been undertaken to reduce the radiation dose to improve patient safety while maintaining image quality. In particular, image reconstruction algorithms have evolved from the traditional analytic algorithms such as filtered back-projection (FBP) to newer iterative reconstruction methods such as adaptive statistical iterative reconstruction (ASiR; GE Healthcare, Milwaukee, Wisconsin) and most recently model-based iterative reconstruction (MBIR; GE Healthcare), which models system noise statistics and optics.Both phantom and clinical studies have confirmed that the application of the MBIR algorithm results in an improved contrast-to-noise ratio (CNR), lower background noise (BN),^1–4 and reduction of helical conebeam artifacts.^2,4 Clinical studies in the delineation of arteries in the posterior fossa on 3D brain CT angiography,¹ improved liver lesion detection,^3,5 general evaluation of abdominopelvic CT,² and pediatric chest CT⁶ all support the use of MBIR, with or without radiation-dose reduction. In this study, we compared objective and subjective image quality in neck CT images reconstructed with 2 different iterative reconstruction algorithms (MBIR versus 30% adaptive statistical iterative reconstruction [ASiR30]) by using the same raw dataset.     

螺旋CT强化方式在肝脏局灶性病变定性诊断中的价值

目的 探讨螺旋CT强化方式对肝脏局灶性病变的定性诊断价值. 方法 回顾性分析行肝脏螺旋CT多期增强扫描且发现局灶性病变的44例患者(54个病灶)的诊断结果,重点分析各类病灶的强化方式. 结果 (1)78%(14/18)的肝细胞癌表现为"快进快出"的强化方式,83%存在肝硬化背景,22%门脉可见癌栓;(2)9个肝血管瘤表现为"快进慢出",边缘明显强化逐渐向中心充填;(3)4例胆管细胞型肝癌表现为"慢进慢出",部分瘤灶内包埋胆管,周围可见扩张的肝内胆管;(4)14个肝转移瘤和5例肝脓肿表现为环形强化,肝转移瘤为周边程度不一的环形强化,肝脓肿则为单环或多环强化;(5)3例肝局灶性结节增生和1例肝细胞腺瘤表现为"快进慢出",2例局灶性结节增生存在中央瘢痕并延迟强化.结论螺旋CT强化方式能充分显示肝脏局灶性病变的血供特点,对定性诊断有较高的临床价值.     

双螺旋CT增强扫描对外伤性肾损伤的诊断价值

肾损伤是较常见的腹部闭合性外伤性疾病,文献报道肾损伤约占腹部闭合性外伤的10%左右[1],近年并有上升趋势.对于肾损伤的分类和范围以及肾脏周围脏器的损伤情况,CT均优于其它影像技术[2].本文收集28例外伤性肾损伤患者,对其CT平扫和增强扫描的影像学表现进行对比研究,以进一步提高CT诊断的准确率.     

多层螺旋CT对下颈部病变的诊断价值

目的 探讨多层螺旋CT(MSCT)在诊断下颈部病变中的价值. 资料与方法 对50例经手术病理或临床证实的下颈部病变患者行MSCT检查,并行最大密度投影(MIP)、多平面重组(MPR)及曲面重组(CPR)等图像后处理,确定病变所在的间隙,根据CT征象确定初步诊断,与最后结果进行对照. 结果 50例中器官间隙病变5例:甲状舌管囊肿3例,部分胸腺颈部异位2例.颈动脉间隙病变10例:副神经节瘤3例,第2鳃裂囊肿2例,淋巴结化脓性炎症2例,癌淋巴结转移3例(合并颈静脉血栓形成2例).咽后间隙病变5例:4例咽后脓肿,1例咽后间隙蜂窝织炎伴反应性淋巴结增生.颈后间隙病变18例:淋巴管瘤4例,海绵状血管瘤3例,脂肪瘤1例,神经纤维瘤病I型1例,淋巴结炎3例,淋巴结结核1例,淋巴瘤1例,癌淋巴结转移4例.多间隙病变12例:颈淋巴结炎及蜂窝织炎2例,淋巴结结核1例,淋巴瘤2例,癌淋巴结转移6例,炎性肌纤维母细胞瘤1例.50例均确定病变所在间隙,42例(84%)病变初步诊断正确. 结论 MSCT可更好地显示下颈部病变所在的解剖间隙,在此基础上结合病变的CT征象可做出准确诊断.     

Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas

BACKGROUND AND PURPOSE:Dynamic contrast-enhanced MR imaging parameters can be biased by poor measurement of the vascular input function. We have compared the diagnostic accuracy of dynamic contrast-enhanced MR imaging by using a phase-derived vascular input function and “bookend” T1 measurements with DSC MR imaging for preoperative grading of astrocytomas.MATERIALS AND METHODS:This prospective study included 48 patients with a new pathologic diagnosis of an astrocytoma. Preoperative MR imaging was performed at 3T, which included 2 injections of 5-mL gadobutrol for dynamic contrast-enhanced and DSC MR imaging. During dynamic contrast-enhanced MR imaging, both magnitude and phase images were acquired to estimate plasma volume obtained from phase-derived vascular input function (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function (K^trans_Φ) as well as plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K^trans_SI). From DSC MR imaging, corrected relative CBV was computed. Four ROIs were placed over the solid part of the tumor, and the highest value among the ROIs was recorded. A Mann-Whitney U test was used to test for difference between grades. Diagnostic accuracy was assessed by using receiver operating characteristic analysis.RESULTS:Vp_ Φ and K^trans_Φ values were lower for grade II compared with grade III astrocytomas (P < .05). Vp_SI and K^trans_SI were not significantly different between grade II and grade III astrocytomas (P = .08–0.15). Relative CBV and dynamic contrast-enhanced MR imaging parameters except for K^trans_SI were lower for grade III compared with grade IV (P ≤ .05). In differentiating low- and high-grade astrocytomas, we found no statistically significant difference in diagnostic accuracy between relative CBV and dynamic contrast-enhanced MR imaging parameters.CONCLUSIONS:In the preoperative grading of astrocytomas, the diagnostic accuracy of dynamic contrast-enhanced MR imaging parameters is similar to that of relative CBV.

Conventional MR imaging by using gadolinium contrast enhancement has been reported to have high sensitivity but low specificity in the preoperative grading of gliomas.^1–4 The accuracy of conventional imaging might be improved by adding perfusion-weighted imaging. In clinical practice, DSC imaging remains the most commonly used perfusion technique and provides semiquantitative measurements such as relative CBV (rCBV), which can be influenced by the presence of susceptibility artifacts and contrast leakage from tumor vessels.^5,6Dynamic contrast-enhanced (DCE)-MR imaging is an alternate technique that can potentially provide absolute values of plasma volume (Vp) and a measurement of vascular permeability referred to as the volume transfer constant (K^trans). This technique generally involves additional measurements and postprocessing steps. Measurements of precontrast tissue T1 and the vascular input function (VIF) in the brain are usually needed for proper quantification of DCE-MR imaging.^7,8 Recently, some authors have suggested that measuring changes in the phase of the MR signal rather than its magnitude following gadolinium injection might provide a more accurate VIF because phase change inside the vessel is linearly related to the concentration of contrast agent.^9–12 While measurement of precontrast tissue T1 is typically included in DCE-MR imaging studies, an additional measurement of tissue T1 postinjection (“bookend” method) might also improve the reproducibility of perfusion values in gliomas.^13,14To our knowledge, there have been few comparative studies between DCE and DSC imaging in patients with gliomas.^15,16 The main objective of our study was to compare the diagnostic accuracy of DCE-MR imaging with DSC-MR imaging in the preoperative grading of astrocytomas at 3T by using a high-relaxivity agent. For DCE-MR imaging analysis, we performed 2 different methods: 1) using phase-derived VIF with bookend T1 measurements; and 2) using magnitude-derived VIF without T1 mapping.     

眼球突出CT诊断价值的探讨（附64例分析）

本文通过６４例眼球突出病例的ＣＴ分析，认为ＣＴ能清楚的显示病变位置及与邻近结构间的关系，且能详细观察病变的内部结构。定位准确率达９６．８８％，定性准确率为８９．６６％。讨论了ＣＴ的诊断价值及某些病变的ＣＴ特征。     

X线、CT对肺癌诊断的评价

目的:评估X线与CT对肺癌的诊断价值。材料与方法:本组收集110例肺癌经X线平片和体层摄影所见及CT表现与手术病理对照分析两者的诊断价值。结果:肿块型(主要为周围型肺癌)在显示分叶和毛刺征像上CT类同X线,但在显示肺内隐蔽部位病灶CT明显优于X线胸片,且CT显示纵隔肺门淋巴结转移较好,其诊断率为72％。但X线胸片及体层摄片在显示肿块整体形态比CT好,特别对中央型肺癌,气管分层能清晰显示受累气管腔内新生物及阻塞面形态。结论:X线平片加体层摄片对肺癌的诊断优于CT,其诊断率96％(CT为93％)。两者互相结合其诊断率达99％。     

CT对嗜铬细胞瘤诊断价值的探讨

本文分析 24例经病理证实的嗜铬细胞瘤CT表现,并与B超手术结果进行了对照,旨在探讨 CT对该病定位、定性诊断价值和对临床治疗的指导作用。24例中,男11例,女13例。起源于肾上腺的肿瘤19例,异位嗜铬细胞瘤5例。CT扫描发现嗜铬细胞瘤具有一些特点:肿块一般较大、密度多不均匀、可伴有液化、坏死、钙化或囊变,增强时肿瘤实质明显强化,而坏死区无或略有强化。结果表明,CT对该病的定位率（95.8％）、定性率（87.5％）均高于B超（定位率83.3％,定性率62.5％）,提示CT是目前嗜铬细胞瘤影像诊断的主要方法。根据肿瘤的CT特点并结合典型的临床表现和生化异常,可进一步提高对嗜铬细胞瘤的诊断率。     

Advanced Modeled Iterative Reconstruction in Low-Tube-Voltage Contrast-Enhanced Neck CT: Evaluation of Objective and Subjective Image Quality

BACKGROUND AND PURPOSE:Dose-saving techniques in neck CT cause increased image noise that can be counteracted by iterative reconstruction. Our aim was to evaluate the image quality of advanced modeled iterative reconstruction (ADMIRE) in contrast-enhanced low-tube-voltage neck CT.MATERIALS AND METHODS:Sixty-one patients underwent 90-kV(peak) neck CT by using third-generation 192-section dual-source CT. Image series were reconstructed with standard filtered back-projection and ADMIRE strength levels 1, 3, and 5. Attenuation and noise of the sternocleidomastoid muscle, internal jugular vein, submandibular gland, tongue, subscapularis muscle, and cervical fat were measured. Signal-to-noise and contrast-to-noise ratios were calculated. Two radiologists assessed image noise, image contrast, delineation of smaller structures, and overall diagnostic acceptability. Interobserver agreement was calculated.RESULTS:Image noise was significantly reduced by using ADMIRE compared with filtered back-projection with the lowest noise observed in ADMIRE 5 (filtered back-projection, 9.4 ± 2.4 Hounsfield units [HU]; ADMIRE 1, 8.3 ± 2.8 HU; ADMIRE 3, 6.7 ± 2.0 HU; ADMIRE 5, 5.4 ± 1.7 HU; all, P < .001). Sternocleidomastoid SNR and internal jugular vein–sternocleidomastoid contrast-to-noise ratios were significantly higher for ADMIRE with the best results in ADMIRE 5 (all, P < .001). Subjective image quality and image contrast of ADMIRE 3 and 5 were consistently rated better than those for filtered back-projection and ADMIRE 1 (all, P < .001). Image noise was rated highest for ADMIRE 5 (all, P < .005). Delineation of smaller structures was voted higher in all ADMIRE strength levels compared with filtered back-projection (P < .001). Global interobserver agreement was good (0.75).CONCLUSIONS:Contrast-enhanced 90-kVp neck CT is feasible, and ADMIRE 5 shows superior objective image quality compared with filtered back-projection. ADMIRE 3 and 5 show the best subjective image quality.

Contrast-enhanced CT is a well-established initial cross-sectional imaging technique for examination of the head and neck region.^1–3 Several strategies have been developed for both radiation dose reduction and improvement of image quality. These typically involve adjusting CT acquisition parameters such as tube voltage, tube current, tube rotation time, pitch, and collimation to the patient body and examined body region.^4–6 The interaction of these parameters is complex, and manual adjustments may result in nondiagnostic images. Thus, commercially available techniques, including tube current modulation,⁷ automatic exposure control,^8,9 automated tube voltage adaptation,^10,11 iterative reconstruction,^12–15 and selective in-plane shielding (thyroid, eye lens, breast, and gonads),¹⁶ have been introduced to support the radiologic technologist, physicist, and radiologist team in developing appropriate CT protocols.Reduced tube voltage can increase contrast-to-noise ratio (CNR) of iodine enhancing soft-tissue structures, while the radiation dose is substantially reduced.⁴ The drawback of an increased image noise in low-tube-voltage examinations can be counteracted by iterative reconstruction, which reduces image noise compared with filtered back-projection (FBP).^12,14 Recently introduced advanced modeled iterative reconstruction (ADMIRE) performs detailed modeling in the projection data domain, resulting in less noise and improved artifact suppression.¹⁷ ADMIRE includes a local signal-to-noise relationship analysis and decomposes the image data into information and noise.¹⁸ Further technical details have been described in recent studies.^14,17,18 Thus, neck CT may potentially be performed with a reduced tube voltage and therefore lower radiation dose without impairing image quality.The purpose of our study was to evaluate the impact of ADMIRE on image quality in low-tube-voltage contrast-enhanced neck CT compared with FBP on a 192-section third-generation dual-source CT (DSCT).     

CT导向下经皮纵隔病变自动切割活检准确率分析

目的探讨影响CT导向下经皮纵隔病变自动切割活检(automated cutting needle biopsy,ACNB)准确性的相关影响因素。资料与方法回顾性分析89例采用CT导向下经皮纵隔病变ACNB的患者资料,以最终诊断结果为金标准,计算穿刺活检诊断恶性病变的敏感性、特异性、阳性预测值、阴性预测值及准确性。应用χ2检验分析不同病变部位、大小、良、恶性及穿刺次数等对穿刺活检准确性的影响。结果 89例纵隔病变穿刺活检患者中有80例与最终诊断结果相符,穿刺活检诊断恶性病变的敏感性、特异性、阳性预测值、阴性预测值、准确性及其95%可信区间分别为90.5%(84.4%～96.6%)、86.7%(79.6%～93.8%)、97.1%(93.6%～100%)、65.0%(55.0%～75.0%)、89.9%(83.6%～96.2%)。经统计学分析,经皮纵隔病变ACNB活检准确性与病灶大小、穿刺次数有统计学意义,穿刺层面病灶越大,活检准确性越高;穿刺次数为3次组活检准确性高于<3次组,而与>3次组无明显差异。结论 CT导向下经皮纵隔病变ACNB对纵隔病变定性诊断准确性高且安全,纵隔病变大小及活检次数可影响活检诊断的准确...     

Diagnostic Accuracy of F-18 FDG-PET in the Assessment of Posttherapeutic Recurrence of Head and Neck Cancer

The purpose of this study was to compare whole-body fluorine-18-fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) with conventional imaging modalities (CI: CT/MRI) in the detection of recurrent head and neck cancer. Whole-body F-18 FDG-PET was performed in 45 patients (recurrence = 39; no recurrence = 16) with previous head and neck cancer. We compared detectability by the period from initial cancer treatment and treatment modalities. Thirty were PET-positive and 15 were PET-negative. The sensitivity, specificity, and accuracy of PET were 97%, 88%, and 93%, respectively (corresponding figures of CI were 73%, 85%, and 77%). In 18 patients who underwent PET less than 3 months after the completion of cancer treatment, the sensitivity, specificity, and accuracy were 100%, 86%, and 94%, while for CI, the corresponding figures were 67%, 71%, and 69%. In 18 patients who had undergone surgery, PET results were 14 true positive and 4 were true negative; significantly higher detectability than CI. Among the patients who were evaluated for more than 6 months or treated by radiotherapy without surgery, diagnostic accuracy was almost the same. Whole body F-18 FDG-PET was a valuable tool in the evaluation of post-therapeutic recurrence of head and neck cancer.     

原发性肝癌经下肢静脉注射造影剂多层螺旋CT增强技术探讨

目的 探讨原发性肝癌经下肢静脉注射造影剂多层螺旋CT(MSCT)增强技术的方法.方法 80例原发性巨块型肝癌按2 ml/kg的剂量注射造影剂行MSCT阈值触发增强扫描.实验组60例分为3个亚组采用3 ml/s、4 ml/s、5 ml/s的注射速率经下肢静脉注射.对照组20例采用3 ml/s的注射速率经上肢静脉注射.分别测量平扫、动脉期、门脉期、平衡期的肝实质、腹腔动脉、肝内肿块的最大增强CT值,统计分析各组间的差异.结果动脉期及门脉期,对照组与实验组5 ml/s组之间的腹腔动脉、肿瘤组织的CT值无统计学差异(P＞0.05),而与实验组3 ml/s、4 ml/s组之间的腹腔动脉、肿瘤组织的CT值有统计学差异(P＜0.05);平衡期,对照组与实验组各组之间的肝实质CT值、以及与实验组4 ml/s、5 ml/s组的腹腔动脉、肿瘤组织的CT值无统计学差异(P＞0.05).结论 在造影剂注射用量相对恒定的条件下,采用MSCT的阈值触发扫描技术,原发性肝癌经下肢静脉5 ml/s的注射速率可以达到经上肢静脉3 ml/s注射速率的增强效果.     

Noise-Optimized Virtual Monoenergetic Dual-Energy CT Improves Diagnostic Accuracy for the Detection of Active Arterial Bleeding of the Abdomen

Purpose

To evaluate diagnostic accuracy of a noise-optimized virtual monoenergetic imaging (VMI+) reconstruction technique for detection of active arterial abdominal bleeding on dual-energy (DE) CT angiography compared with standard image reconstruction.

口服法螺旋CT胆管造影临床应用价值探讨

目的探讨口服法螺旋CT胆管造影对胆系疾病的诊断价值和对胆系手术的指导价值。方法可疑胆系病变患者18例。服用碘番酸后12~14h行CT扫描,并行2D、3DMIP重建。据碘番酸剂量分大剂量组(6.0g)5例,中剂量组(3.0g)10例和小剂量组(1.0g)3例。显影程度分未显影、轻度显影、良好显影和过度显影4级。造影结果与病理和/或临床结果对照。结果(1)胆管显影与碘番酸剂量有关。观察肝内胆管用量不应<6.0g,观察肝总管和胆总管3.0g基本满足要求。(2)口服法螺旋CT胆管造影可显示肝内外胆管特别是肝外胆管的解剖结构,反映胆系功能和其通畅情况以及病变与胆管之间的关系,对胆囊阴性结石和胆囊息肉诊断的敏感度为80%,对胆总管阴性结石诊断的敏感度为88.89%,特异度为100%。(3)2D和3DMIP重建空间感好,是原始图像的重要补充。结论口服法螺旋CT胆管造影简便、无创,是显示肝内外胆管解剖结构和诊断胆系病变的一种较好方法,对胆系手术有指导作用。     

婴幼儿颈部包块超声及临床病理比较研究

目的探讨超声在婴幼儿颈部非炎性肿块诊断中的作用。材料和方法90例非炎性颈部肿块患儿。所有病儿肿块均用ACUSON128xP作探查。得出临床诊断和超声诊断。其中,67例手术治疗获得病理诊断。结果先天性疾病占本组91．1％。常见为囊状水瘤、先天性胸锁乳突肌假性肿瘤、甲状舌管囊肿、血管瘤等。与病理诊断比较,有2例病儿超声误诊,8例病儿临床误诊。超声与临床诊断准确率差别显著。结论对婴幼儿颈部非炎性包块,超声不仅能确定肿块的范围、定位及显示肿块内部回声性质,而且有利于诊断和鉴别诊断。