Hepatic angiomyolipoma: various appearances on two-phase contrast scanning of spiral CT.

The purpose of this study was to describe and analyze the various appearances of hepatic angiomyolipoma (AML) on the two-phase contrast scans of spiral CT and find out the valuable signs suggesting the diagnosis. Spiral CT scanning of pre- and post-contrast arterial phase, portal venous phase were performed in 12 cases. We found that 11 of 12 lesions appeared as hypodense, the other one appeared as slightly hyperdense on pre-contrast CT scans. On the arterial phase, 11 lesions were markedly enhanced, with the central vasculature opacification in eight lesions; the only other lesion showed no marked enhancement, but with massive vessels seen within the lesion. On the portal venous phase, eight lesions remained in enhancement with the central vessels also seen in six lesions. Our results revealed that two-phase contrast scanning could demonstrate some characteristic features of AML, such as fat components within the lesions, hypervascular tumors, the absence of capsule. Especially the central vessels within the lesions suggested strongly the diagnosis of AML. As for atypical cases, the diagnosis remained difficult and should be differentiated from other hypervascular lesions by means of other imaging modalities or needle puncture biopsy.     

胸部多层螺旋CT低剂量扫描的研究进展

X线计算机体层成像（X-ray computed tomography,CT）自1972年问世以来,得到了快速发展和普及,其检查范围在逐步扩大。多层螺旋CT容积扫描的实现提高了病变的检出率和诊断的准确率,临床应用日益广泛,受检群体的有效受照剂量也在增加,如何在最大限度地满足CT诊断前提下,降低CT剂量,已受到越来越多的关注。     

Dynamic CT of hepatic masses with intravenous and intraarterial contrast material

Seven patients with primary and metastatic hepatic tumors had dynamic computed tomographic scans obtained after an intravenous and an intrahepatic arterial bolus of contrast media. Four patients had hepatoma and three had hepatic metastasis from either a colonic, pancreatic, or leiomyosarcoma primary malignancy. Computed tomography was also performed after an intravenous drip infusion of contrast material. Time-density curves of the hepatic lesions after contrast administration were analyzed and compared. The results demonstrated that: (1) intrahepatic arterial delivery of contrast fluid resulted in the greatest contrast enhancement of lesions and detected more lesions than the intravenous bolus technique, which was superior to the drip infusion technique; (2) no consistent difference in the pattern of contrast enhancement was found between various hepatic lesions; (3) within multiple lesions of similar pathology in any one liver, a spectrum of contrast enhancement pattern was found; and (4) changes in contrast enhancement occurred rapidly and lesions changed from hypodense to isodense to hyperdense to isodense within 30--45 sec.     

小剂量对比剂胸部CT增强检查

目的 评价小剂量对比剂在胸部CT增强检查中的可行性.方法 抽取104例胸部CT增强检查,常规剂量与小剂量法进行对比分析.结果 46例小剂量胸部CT增强效果较满意,与常规剂量无显著区别.结论 如无高压注射器,小剂量胸部增强可以作为一种常规增强方法.     

Contrast-enhanced spiral CT of the head and neck: comparison of contrast material injection rates.

BACKGROUND AND PURPOSE: Contrast-enhanced spiral CT studies of the head and neck are performed frequently using contrast material volumes of approximately 30 g iodine and a scan delay of 30-45 seconds. Because little is known about the effects of contrast material injection rates on tissue enhancement, this was prospectively investigated in our study. METHODS: Ninety-seven patients underwent spiral CT of the head and neck. Each patient was assigned randomly to one of four groups who received 100 mL of nonionic contrast material (300 mg I/mL) at different monophasic injection flow rates with 1.5, 2, 3, and 4 mL/s. Scanning started after a constant delay of 35 seconds. The attenuation of the carotid artery, jugular vein, and sternocleidomastoid muscle was measured over time and the attenuation of the submandibular and thyroid gland was evaluated. Vascular attenuation of at least 150 HU was considered to be sufficient. RESULTS: The mean scan time was 33+/-5 seconds. The study, using an injection rate of 2 mL/s, showed the longest time of sufficient overall (arterial and venous) vessel attenuation (27+/-4 seconds, P< or =.008). The injection flow rate did not influence significantly muscular attenuation (mean enhancement during scan time: 9+/-7 HU). The 1.5 mL/s protocol showed the lowest attenuation values of the submandibular gland (81+/-12 HU) and the highest attenuation values of the thyroid gland (164+/-22 HU), but the attenuation of the thyroid gland was not statistically different from that revealed by the 2 mL/s protocol. CONCLUSION: Using 100 mL of intravenous contrast material with 300 mg I/mL for spiral CT studies of the entire head and neck, the optimal injection flow is 2 mL/s, whereas lower flow rates resulted in insufficient venous enhancement.     

Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material

PURPOSE: To compare the diagnostic accuracy of focused helical computed tomography (CT) with orally administered contrast material with that of nonfocused helical CT with orally and intravenously administered contrast material. MATERIALS AND METHODS: After receiving oral contrast material, 228 patients with clinically suspected appendicitis underwent focused appendiceal CT (5-mm section thickness, 15-cm coverage in the right lower quadrant). Immediately thereafter, helical CT of the entire abdomen and pelvis was performed following intravenous administration of contrast material (abdomen, 7-mm section thickness; pelvis, 5-mm section thickness). Studies were separated and independently interpreted by three observers who were blinded to patient names. Diagnoses were established by means of surgical and/or clinical follow-up findings. RESULTS: Fifty-one (22.4%) of 228 patients had acute appendicitis. Readers diagnosed appendicitis with 83.3%, 73.8%, and 71.4% sensitivity and 93.0%, 92.3%, and 97.9% specificity with focused nonenhanced appendiceal CT. Readers diagnosed appendicitis with 92.9%, 92.9%, and 88.1% sensitivity and 93.7%, 95.1%, and 96.5% specificity with nonfocused enhanced CT. Summary areas under the receiver operating characteristic curve estimates for focused nonenhanced and nonfocused enhanced CT were 0.916 and 0.964, respectively; the differences were statistically significant (P <.05) for two of three readers. All readers demonstrated higher sensitivities for detecting the inflamed appendix with nonfocused enhanced CT. Appendicitis was missed with focused CT in two patients whose inflamed appendix was not included in the imaging of the right lower quadrant. All readers were significantly more confident in diagnosing alternative conditions with nonfocused enhanced CT. CONCLUSION: Diagnostic accuracy of helical CT for acute appendicitis improved significantly with use of intravenous contrast material.     

多层螺旋CT胰腺检查:两种注射条件对增强效果的影响研究

目的　探讨多层螺旋CT(MSCT)胰腺检查方案中 ,2种注射条件对增强效果的影响。方法　 4 0例无胰腺疾病患者 ,用抽签法将其随机分为 2组 ,每组各 2 0例。A组注射条件为 :对比剂总量为 12 0ml,注射流率为 5ml/s;B组注射条件为 :对比剂总量为 90ml,注射流率为 3ml/s。分别行平扫及胰腺三期 (包括动脉期、胰腺期及肝脏期 )增强扫描 ,比较两组间胰腺期胰腺实质强化程度、胰周主要血管的显示率及显示程度 (根据血管显示的清晰程度评为 0～ 3分 )。结果　A组胰腺期胰腺实质强化程度明显高于B组 (t=3 5 9,P <0 0 1) ,胰周大血管 (动脉指腹腔动脉、肝动脉、脾动脉及肠系膜上动脉 ,静脉指门静脉、脾静脉及肠系膜上静脉 )的显示率 ,A组及B组均为 10 0 % ;胰周其他主要血管(动脉包括胃十二指肠动脉及胰十二指肠前上、后上、前下、后下动脉 ,静脉包括胃结肠干及胰十二指肠前上、后上静脉 )的显示率 ,A组为 5 0 %～ 10 0 % ,B组为 10 %～ 95 % ,两组间差异有显著性意义 (χ2=2 6 2 7,P =0 0 0 )。胰周大血管及胰周其他主要血管的显示程度 ,A组各血管平均评分值分别为2 93～ 3 0 0与 0 6 0～ 2 80 ,B组分别为 2 33～ 2 80与 0 0 7～ 1 5 3,两组间差异均有显著性意义(U =0 0 0及 12 5 0 ,P =0 0 0及 0 0 4 )     

低剂量对比剂320排CT冠状动脉成像可行性研究

目的:探讨单次心跳内采集数据320排CT冠状动脉成像时低对比剂用量的可行性。方法:将131例行冠状动脉CTA检查的病例分为3组,A组对比剂剂量为0.8ml/kg,注射流率4.5ml/s;B组对比剂剂量0.7ml/kg,注射流率5.0ml/s;C组对比剂剂量0.6ml/kg,注射流率5.5ml/s。所有病例心率均<70次/分,单心跳采集心脏数据。分别在主肺动脉干、升主动脉、右冠状动脉和左冠状动脉主干内选择相同的兴趣区测量其CT值,采用单因素方差分析比较3组病例动脉强化程度的差异。结果:C组主肺动脉干CT值为(185.40±46.74)HU,强化程度最低,与A组和B组[分别为(225.77±79.69)和(216.79±51.06)HU]间差异有统计学意义(P<0.05);各组之间升主动脉、右冠状动脉和左冠状动脉主干强化程度差异无统计学意义(P>0.05)。结论:320排CT冠状动脉成像能显著降低单心跳扫描患者对比剂用量,并保证冠状动脉足够程度的强化。     

CT dose reduction using prospectively triggered or fast-pitch spiral technique employed in cardiothoracic imaging (the CT dose study)

ObjectivesTo establish current radiation dose levels with contemporary scanners capable of prospectively triggered or high-pitch spiral scan modes to previous generation scanners among patients evaluated for coronary artery disease, pulmonary embolism, aortic disease, and “triple rule out” in a large population of patients at multiple centers.BackgroundPrevious small-scale studies with carefully controlled scan protocols report that CT scanners that facilitate prospectively triggered scanning and provide high-pitch spiral CT scan modes drastically lower radiation doses. However, diagnostic reference levels should be selected by medical bodies on the basis of large surveys of representative sites and reviewed at appropriate time intervals.MethodsScan data including dose and image quality parameters were collected retrospectively from 64 slice scanners (control) and prospectively after sites installed 128-slice dual-source scanners with high-pitch capability (study). Protocol selection was purposely not specified to survey “real world” results. Blinded quantitative image analysis was performed on every fifth scan.ResultsFrom April 2011 to March 2012, 2085 patients at 9 sites completed the study: 1051 coronary artery disease (509 control, 542 study), 528 pulmonary embolism (267 control, 261 study), 419 aortic disease (268 control, 151 study), and 87 triple rule out (53 control, 34 study). There was a significant reduction in median dose-length product (DLP) from 669 mGy∙cm (interquartile range [IQR]: 419–1026 mGy∙cm) in the control group to 260 mGy∙cm (IQR: 159–441 mGy∙cm) in the study group, a reduction by 61% (P < .0001) and was lower in all categories. No significant differences were noted in image quality.ConclusionUse of advanced scanners facilitating prospectively triggered or high-pitch spiral scan modes results in marked dose reduction across a variety of cardiovascular studies, with no compromise in image quality. These findings may contribute to new target dose recommendations in societal guidelines.     

Feasibility of low dose contrast material administration in CT coronary angiography using 320-detector CT scanner

目的:探讨单次心跳内采集数据320排CT冠状动脉成像时低对比剂用量的可行性.方法:将131例行冠状动脉CTA检查的病例分为3组,A组对比剂剂量为0.8ml/kg,注射流率4.5ml/s;B组对比剂剂量0.7ml/kg,注射流率5.0ml/s;C组对比剂剂量0.6ml/kg,注射流率5.5ml/s.所有病例心率均＜70次/分,单心跳采集心脏数据.分别在主肺动脉干、升主动脉、右冠状动脉和左冠状动脉主干内选择相同的兴趣区测量其CT值,采用单因素方差分析比较3组病例动脉强化程度的差异.结果:C组主肺动脉干CT值为(185.40±46.74)HU,强化程度最低,与A组和B组[分别为(225.77±79.69)和(216.79±51.06)HU]间差异有统计学意义(P＜0.05);各组之间升主动脉、右冠状动脉和左冠状动脉主干强化程度差异无统计学意义(P＞0.05).结论:320排CT冠状动脉成像能显著降低单心跳扫描患者对比别用量,并保证冠状动脉足够程度的强化.     

Abdominal multidetector row computed tomography: reduction of cost and contrast material dose using saline flush

OBJECTIVE: To evaluate the potential of a saline solution flush after the contrast material bolus in abdominal multidetector row CT (MDCT) in contrast material dose and cost reduction. METHODS: Abdominal MDCT was performed in 78 patients who were assigned randomly to 2 groups receiving 120 mL nonionic contrast material (300 mgI/mL) alone or 100 mL of the same contrast material pushed with 40 mL of saline solution. Mean attenuation values for both groups were measured in the liver, the spleen, the pancreas, the portal vein, the inferior vena cava, and the abdominal aorta. Cost analyses were performed for both groups. RESULTS: There was no significant difference in parenchymal and vascular enhancement between both groups. The difference of the enhancement was 2 HU for the liver (P = 0.11), 2 HU for the spleen (P = 0.44), 3 HU for the pancreas (P = 0.38), 9 HU for the portal vein (P = 0.11), 3 HU for the inferior vena cava (P = 0.55), and 10 HU for the aorta (P = 0.06). Taking the costs of contrast material, saline solution, and disposal material into account, 7.30 dollars was saved by the patient using a saline solution flush. CONCLUSIONS: Using a saline flush after the contrast material bolus in abdominal MDCT allows an iodine dose reduction of approximately 6 g, or 17%, without impairing mean parenchymal and vascular enhancement and a cost reduction of 7.30 dollars per patient.     

低剂量螺旋CT扫描技术

降低受检者CT检查辐射剂量一直是业内关心的热点问题。本文从CT辐射剂量的表达方法,图像质量评价指标,影响辐射剂量的因素以及低剂量扫描方案的合理应用等方面,介绍了低剂量螺旋CT扫描技术的研究进展。