Fungal liver infection in immunocompromised patients: depiction with multiphasic contrast-enhanced helical CT

PURPOSE: To retrospectively assess multiphasic (nonenhanced, arterial phase, and portal venous phase) computed tomography (CT) of the liver for depiction of hepatic fungal infection in immunocompromised patients. MATERIALS AND METHODS: The institutional ethics review board approved the study and waived the requirement for informed consent. Sixty multiphasic hepatic CT examinations were performed in 39 immunocompromised patients who fulfilled the criteria for having probable or proved fungal liver infection. The detection and conspicuity of focal liver lesions were assessed on scans obtained during each CT phase. The lesion enhancement pattern was determined, and, accordingly, lesions were stratified into two groups: lesions suggestive of infection (with ring enhancement patterns or high attenuation) and nonspecific hypoattenuating lesions. Statistical analyses were performed by using logistic regression with generalized estimating equations. RESULTS: A total of 536 liver lesions detected at 36 CT examinations with results positive for fungal infection were assessed. All 36 (100%) examinations yielded positive results during the arterial phase, whereas 25 (69%) of them yielded positive results during the portal venous phase (P < .001). At lesion-by-lesion analysis, the arterial phase scans depicted significantly more lesions (483 of 536 [90%]) than the portal venous phase (329 of 536 [61%]) and nonenhanced (265 of 465 [57%]) scans (P < .001 for both comparisons). In addition, on arterial phase scans, 386 of 483 lesions, as compared with 134 of 329 lesions on portal venous phase scans (P < .001), were judged to have an enhancement pattern suggestive of infection. The CT phases did not differ significantly in terms of the conspicuity of detected lesions. CONCLUSION: In patients suspected of having hepatic fungal infection, arterial phase CT depicts significantly more hepatic lesions than does CT performed during the other phases, and it reveals more lesions with enhancement patterns suggestive of infection. Arterial phase CT should be performed in addition to portal venous phase CT in patients suspected of having hepatic fungal infection.     

Utility of dual phase liver CT for metastatic melanoma staging and surveillance

Rationale and objectives

To evaluate the clinical utility of dual phase computed tomography (CT) for assessment of hepatic metastases in patients with metastatic melanoma.

Materials and methods

A retrospective case–control study of dual phase CT examinations consisting of late hepatic arterial and portal venous phases performed on patients with melanoma was undertaken. In 2010, 420 dual phase CT examinations were performed on 188 patients. Of these, 46 CT examinations on 24 patients with hepatic metastases were combined with 52 control studies for evaluation. Two blinded reviewers independently evaluated single portal venous phase alone and dual phase imaging on separate occasions. The presence of hepatic lesions, the conspicuity of the lesions, and the likelihood that the detected lesions were metastases was recorded. Agreement between readers, sensitivity and specificity was calculated.

Results

In no case was hepatic metastatic disease only apparent on arterial phase imaging. Arterially enhancing hepatic lesions only visible on the arterial phase or much more conspicuous on the arterial phase were present in 10 studies (10%), all of which were benign. Liver metastases were rated as being more accurately assessed on the portal venous phase in up to 100%. In a per scan analysis dual phase and venous phase imaging had similar sensitivities of 96% (95%, CI: 86–100) and 98% (95%, CI: 89–100), respectively.

Conclusion

Single portal venous phase imaging is adequate for staging and surveillance in patients with metastatic melanoma.     

Multiphase contrast-enhanced helical CT of liver metastases from renal cell carcinoma

The aim of this study was to evaluate whether in patients with metastatic renal cell carcinoma (RCC) multiphase liver studies would improve detection of metastatic liver disease. Forty-six consecutive patients with known metastatic RCC underwent standardized non-contrast and triphasic contrast enhanced hepatic CT examinations as part of their routine imaging studies. Once a liver abnormality was detected, it was characterized as metastatic by a panel of three radiologists who followed pre-set criteria. These criteria included change in size, biopsy results and lack of benign features. Presence and conspicuity of liver metastases were graded using a five-point scale by consensus of a panel of three radiologists. The highest number of lesions evaluated per patient was limited to ten. Seventy-two liver metastases were detected in 16 patients. Of these, 54 were seen on unenhanced scans; 47 in the hepatic arterial (HA) phase, at 25 s; 65 in the portal-venous (PV) phase, at 60 s; and 49 in delayed images, at 90 s. Scanning only during the PV phase would have missed seven lesions (10%), six of which were seen on unenhanced images and six were seen in HA phase. All patients with metastatic liver disease would have been identified by combination of unenhanced and PV phase or by HA and PV phase scanning. Forty-two lesions were graded more conspicuous on the PV phase, whereas 18 (25%) were more conspicuous on the HA phase. The combination of unenhanced, HA and PV scanning should be considered in the initial evaluation of patients with metastatic RCC for improved lesion detection and characterization. Subsequently, the combination of unenhanced and PV phase imaging is preferred.     

双源CT双能量上腹部虚拟平扫临床应用价值的初步探讨

目的 探讨双源CT(dual source computed tomography,DSCT)上腹部双能量虚拟平扫临床应用的可行性.资料与方法 对46例临床拟诊上腹部病变患者行DSCT上腹部常规平扫(CNCT)及动脉期、门静脉期双能量扫描(80 kV/404 mA和140 kV/96 mA).利用Liver VNC软件处理分别得到动脉期、门静脉期2组虚拟平扫数据,并与CNCT对照,比较三者在图像质量、辐射剂量、平均CT值、信噪比(SNR)及病灶检出上差异的统计学意义.结果 3次扫描患者接受的辐射剂量、所测肝、脾平均CT值的差异无统计学意义(P>0.05);虚拟平扫图像SNR明显高于CNCT组(P=0.00),2组虚拟平扫之间差异无统计学意义(P>0.05);虚拟平扫的图像质量较CNCT有所下降(F=241.80,P=0.00),但可满足临床诊断需求,动脉期虚拟平扫图像质量优于门静脉期(P=0.004);虚拟平扫和CNCT病灶检出性能相似.结论 相对门静脉期而言,肝动脉期的双能量虚拟平扫能提供更好的图像质量,可满足诊断需要,并可减少一次平扫的辐射剂量,具有更高的SNR、相似的病灶检出性能,具有潜在的临床应用价值.     

肝脏炎性假瘤的CT及MRI征象

目的:探讨肝脏炎性假瘤的CT和MRI表现。方法:8例经手术病理证实的肝脏炎性假瘤。男5例,女3例,年龄35~65岁,平均53岁。8例均作CT平扫及增强扫描,其中3例行MR对比检查。结果:CT表现为1 个病灶6 例,2个病灶2例,共发现病灶10个。平扫9个病灶表现为低密度,1 个病灶表现为稍高密度。动态增强扫描2 个病灶动脉期显著强化,门脉期及延迟期中度强化;8个病灶动脉期无明显强化,门脉期及延迟期有不同方式的强化,主要表现为周边完整或不完整的环形或结节状强化,中心核心样强化及线状或不规则分隔样强化。MRI表现为2 例病灶T1WI呈低信号,T2WI呈稍高信号,1例病灶T1WI及T2WI均为等信号,动态增强扫描与CT相仿。结论:肝脏炎性假瘤的CT及MRI表现因其病理阶段不同而表现各异,诊断需结合临床,确诊尚依靠病理检查。     

肝脏双期螺旋CT扫描的临床应用价值

目的:研究双期螺旋CT最佳扫描技术及其在肝肿瘤或肝癌探测中的应用。材料与方法:35例无肝肿瘤和17例肝肿瘤患者均经双期螺旋CT行肝脏扫描,于动脉期和门静脉期观察了正常肝脏和肝细胞癌病灶中的CT表现。结果:正常肝脏与肝细胞癌的CT表现有明显不同。在12例肝细胞癌患者中确切看到了14个肝细胞癌病灶,其中13个病灶在动脉期呈高密度,12个病灶在门静脉期呈低密度,动脉期和门静脉期肝细胞癌的检出率分别为92.8％和85.7％。结论:选择最优化扫描参数,可清晰显示肝细胞癌的增强特点,并显著提高其病变的检出率,因此,双期螺旋CT扫描可当作探测肝肿瘤或肝细胞癌的常规方法。     

Eosinophilic hepatic necrosis: magnetic resonance imaging and computed tomography comparison

OBJECTIVE: To compare the findings of magnetic resonance (MR) imaging with those of computed tomography (CT) of focal liver lesions related to peripheral eosinophilia. METHODS: For 12 patients with peripheral eosinophilia (>7%) examined with hepatic MR imaging and CT, 52 focal hepatic lesions larger than 0.5 cm, including 31 lesions simultaneously found on the 2 imaging modalities, were subjected to a comparative analysis of their imaging features. RESULTS: The total number of lesions distinguished from background liver was 39 (75%) on MR imaging and 44 (85%) on CT scans. On arterial phase images of 10 patients with comparable data, homogeneously hyperintense lesions were demonstrated more frequently (P = 0.006) on MR imaging (16 [50%] of 32 lesions) than on CT scans (4 [13%] of 32 lesions). Only 7 (22%) of the 32 hypoattenuating lesions on portal phase CT were depicted as hypointense lesions on portal phase MR images in 12 patients. On delayed phase images in 8 patients, the number of hyperintense lesions on MR images (9 [56%] of 16) was greater (P = 0.077) than that seen on the CT scans (4 [25%] of 16). CONCLUSIONS: For many focal hepatic lesions related to peripheral eosinophilia, dynamic MR imaging more easily demonstrates lesional enhancement on arterial and delayed phases than CT scans. Because of the higher degree of lesional enhancement of MR imaging compared with CT, the lesion-to-liver contrast may not be sufficient to distinguish the lesion from the background liver, resulting in decreased sensitivity of portal phase dynamic MR imaging.     

Multidetector CT: contributions in liver imaging

Multidetector CT has had great impact in the evaluation of the liver. Increased speed combined with thin slice collimation improved the spatial and temporal resolution, which in turn provided a higher sensitivity in the detection of focal lesions, particularly for the hepatocellular cancer (HCC) in patients with cirrhosis. There is no consensus as to whether the so-called "double arterial phase scanning" improves the detection rate of hepatocellular cancers, and the majority of the more recent studies suggest acquiring only the late arterial phase images along with the portal venous phase images. However, if the patient is a surgical candidate, the early arterial phase images must also be obtained, because they provide better pre-surgical mapping of the hepatic arteries. In primary and metastatic liver tumors, arterial and portal venous phase images should be acquired with thin collimation and overlapping reconstruction. Maximum intensity projection and volume rendering methods demonstrate the three-dimensional anatomy of the hepatic arteries, portal and hepatic veins successfully, which provide useful information before hepatic resection or intraarterial chemotherapy. In living donor candidates, early arterial and portal venous phase images obtained with thin collimation and overlapping reconstruction are used to reconstruct three-dimensional images with maximum intensity and volume rendering methods. These have a high sensitivity to detect hepatic artery, portal and hepatic vein variations, which could render the surgery difficult or even impossible. Portal venous phase images can also be used to measure total and lobar liver volumes. A virtual hepatectomy plane can be simulated on the three-dimensional model of the liver and hepatic veins, and when necessary, its location can be modified according to the metabolic needs of the recipient and donor. Thin collimation and better temporal resolution may also have beneficial effects in the characterization of liver lesions.     

肝脏囊性转移瘤的CT和MR征象的比较

目的:分析肝脏囊性转移瘤在CT和MR上的表现,比较CT和MR检查对囊性转移瘤的临床诊断价值.材料和方法:18例(共52个病灶)肝脏囊性转移瘤中10例行CT平扫和增强门脉期扫描.8例行MR T1WI和FMP-SPGR多期动态增强扫描.观察肿瘤的大小、形态、数目、囊壁和壁结节的强化情况.结果:2例为单发病灶外,其余均为多发病灶.病灶呈类圆形或椭圆形.CT上8例见到囊壁不规则增厚,其中6例可见向囊腔内突起的壁结节,1例内有分隔.2例薄壁且均匀的病灶误诊为肝囊肿.T1WI上,7例为低信号,1例为混杂信号.T2WI上,病灶均为明显高信号,2例信号均匀,6例信号不均匀,可见到壁结节为略低信号.增强动脉期所有病灶均无强化表现,门脉期和延迟期,可见到边缘环形强化和壁结节的强化.也有1例见到分隔.结论:CT和MR均可显示肝脏囊性转移瘤的特征,MR在显示病灶的出血、囊变、分隔和囊壁的情况等比CT更为敏感、可靠,在鉴别诊断方面价值更大.     

Multidetector CT of the liver and hepatic neoplasms: effect of multiphasic imaging on tumor conspicuity and vascular enhancement

OBJECTIVE: Our aim was to determine which of three contrast-enhanced phases (early arterial, late arterial, or portal venous) was optimal for achieving maximal enhancement of the celiac artery, portal vein, and hepatic parenchyma. We also wanted to learn which phase provided the maximal tumor-to-parenchyma difference when using multidetector CT (MDCT) with fixed timing delays. MATERIALS AND METHODS: Fifty-two patients with suspected or known hepatic tumors underwent multiphasic contrast-enhanced MDCT using double arterial (early and late arterial) and venous phase acquisitions with fixed timing delays. All patients were administered 150 mL of IV contrast material at an injection rate of 4 mL/sec. Images were acquired at 20 sec for the early arterial phase, 35 sec for the late arterial phase, and 60 sec for the portal venous phase. Attenuation measurements of the celiac artery, portal vein, normal hepatic parenchyma, and the hepatic tumor were compared. Three reviewers independently and subjectively rated tumor conspicuity for each of the three phases. Ratings were compared using kappa statistics. RESULTS: Late arterial phase images showed maximal celiac axis attenuation, whereas portal venous phase images revealed the highest portal vein and normal hepatic parenchymal attenuation. Maximal tumor-to-parenchyma differences for hypovascular tumors was superior in the portal venous phase, but we found no significant differences in maximal tumor-to-parenchyma differences for hypervascular tumors among the evaluated phases. On subjective analysis, interobserver agreement was moderate to very good for the three phases. All three reviewers graded both hypovascular and hypervascular tumor conspicuity as superior in either the late arterial phase or the portal venous phase in most patients. In only one patient was the early arterial phase graded as superior to the late arterial and portal venous phases (by two of the three reviewers). CONCLUSION: When MDCT of the liver is performed using fixed timing delays, maximal vascular and hepatic parenchymal enhancement is achieved on either late arterial phase or portal venous phase imaging. In most patients, early arterial phase imaging does not improve tumor conspicuity by either quantitative or subjective analysis.     

小肠平滑肌类来源肉瘤肝转移CT及血管造影表现(附7例报告)

目的　分析小肠平滑肌类来源肉瘤肝转移的CT表现和肝动脉造影表现。材料与方法　回顾性分析 7例小肠平滑肌类肉瘤肝转移病例 ,肝脏转移肿瘤共 46个。 7例均行肝脏CT三期扫描和肝动脉造影。结果　肝脏转移病灶CT平扫呈低密度实性或囊实性占位。肿瘤膨胀生长 ,与周围肝实质分界清楚。动脉期增强扫描肿瘤实质部分明显强化 ,门脉期与周围肝实质强化差异缩小。肿瘤囊变坏死区无强化。肝动脉造影示转移肿瘤血管和染色丰富。结论　小肠平滑肌类来源肉瘤肝转移以肝动脉供血为主 ,为富血供肿瘤 ,类似于肝细胞癌。肿瘤多伴有明显囊变坏死     

Discrimination of small hepatic hemangiomas from hypervascular malignant tumors smaller than 3 cm with three-phase helical CT

PURPOSE: To compare the appearance of small hepatic hemangiomas at nonenhanced and contrast material-enhanced helical computed tomography (CT) with that of small (<3-cm) hypervascular malignant liver tumors and to evaluate the accuracy of multiphase helical CT for differentiating small hemangiomas from small hypervascular malignant tumors. MATERIALS AND METHODS: Radiologists reviewed multiphase helical CT liver images in 86 patients with 37 hemangiomas and 49 malignant liver tumors. They evaluated lesion type and degree of enhancement for change from arterial to portal venous phase. They rated their confidence in the discrimination of hemangiomas from malignant tumors. RESULTS: At arterial phase CT, enhancement similar to aortic enhancement was observed in 19%-32% of hemangiomas and 0%-2% of malignant tumors; globular enhancement, in 62%-68% and 4%-12%, respectively. At portal venous phase CT, enhancement similar to blood pool enhancement was observed in 43%-54% of hemangiomas and 4%-14% of malignant tumors; globular enhancement, in 46%-49% and 0%-2%, respectively. For all readers and all phases of enhancement, the area under the receiver operating characteristic curves was 0.81-0.87, indicating that inherent accuracy of CT is high and that there was no significant difference (P >.28) in overall accuracy. Readers diagnosed hemangiomas with 47%-53% mean sensitivity with all enhancement phases and diagnosed malignant lesions with 95% mean specificity. CONCLUSION: Small hemangiomas frequently show atypical appearances at CT. Two-phase helical CT does not improve sensitivity but does improve specificity for differentiating hemangiomas from hypervascular malignant tumors.     

螺旋CT双期或三期扫描对肝脏占位性病变的诊断

目的：分析肝脏螺旋CT双期或三期扫描表现，探讨其对原发性肝癌、肝转移瘤、肝血管瘤的诊断及鉴别诊断的意义。方法：经临床证实25例，均作螺旋CT平扫、动脉期、门脉期及部分平衡期和延迟期扫描，并分析螺旋CT多期扫描表现。结果：原发性肝癌动脉期明显强化而肝脏无强化，形成鲜明的对比，门脉期呈相对低密度或恢复到平扫时表现。肝血管瘤CT特征为动脉期呈边缘性环状、结节样强化，门脉期病灶边缘强化向中心强化并充满病灶呈高密度，平衡期呈等密度或低密度肝转移瘤表现多样化，周边强化或不均匀强化或不强化。结论：螺旋CT双期或三期扫描已作为对肝脏占位性病变的主要检查方法，并作为常规。     

原发性肝癌多层面CT双动脉期与门静脉期增强扫描分析

目的：探讨原发性肝癌多层面CT（multi-slices CT,MSCT）双动脉期与门静脉期增强扫描各期强化特征及癌灶的检出率。方法：104例原发性肝癌治疗前行MSCT的平扫与三期扫描（双动脉期与门静脉期扫描）,对比剂用量100 ml,以3 ml/s的速率肘静脉注射,采集时间动脉早期20～22 s,动脉晚期34～37 s,门静脉期60 s。测病灶平扫及各增强期CT值,分析病灶的强化情况及检出情况,以增强各期检出的肿瘤数目为肿瘤灶总数。结果：三期增强扫描共显示470个病灶,34个均匀强化;436个不均匀强化,〈3 cm病灶动脉早期检出117个（56.25%）,动脉晚期检出171个（82.21%）,门静脉期检出137个（65.86%）,≥3 cm的病灶动脉早期检出237个（90.45%）,动脉晚期检出250个（95.41%）,门静脉期检出244个（93.12%）。56个仅在三期增强扫描的一期显示,动脉早期5个,动脉晚期25个,门静脉期26个。结论：动脉晚期的检出率明显高于门静脉期与动脉早期。双动脉期与门静脉期增强扫描有利于提高肝癌检出效率。     

肝腺瘤的综合影像诊断

目的：描述肝腺瘤的超声（US），CT和MRI表现与病理基础，探讨综合影像对肝腺瘤的诊断价值。方法：回顾性分析经手术切除，病理症实的6例肝腺瘤的US，CT和MRI表现，并与病理所见对照。结果：6例肝腺瘤均为单发肿块，1例术前综合影像诊断为肝腺瘤，4例误诊为肝癌，例误诊为肝局灶结节性增生。US：6例呈稍低或低回声，4例有低回声晕，彩色多普勒显示6例肿块内有较丰富的门脉样血流和低速动脉样血流，CT：6例为稍低或低密度，4例有假包膜，4例动脉期，门脉期均轻度强化，1例动脉期中度强化，门脉期轻度强化，MRI：T1WI和T2WI上，6例表现为以高信号为主的混杂信号，用脂肪抑制后T1WI上的高信号无变化；2例动脉期显著强化，门脉期和延迟期轻度强化，3例动脉期，门脉期和延迟基匀轻度强化。6例均有假包膜，且在门脉期或延迟期现轻度强化。结论：肝腺瘤的综合影像表现缺乏特性性。对有假包膜和混杂高信号（用脂肪抑制后T1WI上的高信号无变化）的多血供肿块应考虑到肝腺瘤的诊断。     

Multiple-phase spiral computerized tomography of small hepatocellular carcinoma: technique optimization and diagnostic yield

PURPOSE: Spiral imaging has dramatically increased the diagnostic capabilities of Computed Tomography (CT) in the evaluation of small hepatocellular carcinomas (HCCs, O < 3 cm). We report our experience with multiple-phase CT of small HCC relative to both examination technique and lesion patterns. We compared the yield of biphasic (arterial-dominant + portal-dominant phases) and triphasic (arterial-dominant + portal-dominant + delayed phases) and also reviewed the literature for a meta-analysis of the techniques used. MATERIAL AND METHODS: December 1996 to July 1998, forty-eight patients with small nodular HCCs were examined--98 nodules in all (range 1-9, mean 2 per patient). After baseline CT, a nonionic contrast agent (350 mgI/mL, 130-140 mL, 4 mL/s) was administered through a power injector and a 16-gauge needle. Biphasic volume images were acquired in 19 subjects (early-phase delay 24 s, venous-phase delay 75 s) and triphasic images in 29 (early-phase delay 24 s, venous-phase delay 60 s, delayed-phase delay 100 s). Retrospectively we assessed the number of nodules detected with each protocol in every phase, nodule conspicuity (graded I-IV) relative to surrounding parenchyma, and nodule patterns in the various phases. Nodule patterns were distinguished into homogeneous, peripheral, central and mixed hyperdensity, and homogeneous hypodensity. RESULTS: Thirty-seven lesions were found in the patients examined with the biphasic technique: baseline images showed 35% of the nodules, arterial images 92%, portal images 76% and combined arterial and portal acquisitions 95%. Sixty-one lesions were found in the patients examined with the triphasic technique: baseline images showed 43% of the nodules, arterial images 93%, portal images 70%, and delayed images 77%; combined arterial and portal acquisitions detected 93% of the nodules, combined arterial and delayed images 95%, combined arterial and delayed images 80%. Finally, 95% of lesions were demonstrated when the three phases were combined. Overall conspicuity grades were I in 44% of cases, II in 28%, III in 18% and IV in 10% of cases at baseline scanning; I in 9%, II in 24%, III in 34% and IV in 33% in the arterial phase; I in 28%, II in 41%, III in 18% and IV in 13% in the portal phase; I in 23%, II in 30%, III in 26% and IV in 21% of cases in the delayed phase. At baseline, 10% of lesions were hyperdense (homogeneously and peripherally in 5% each); mixed density was seen in 8%, and hypodensity in 82%. In the arterial phase, 93% of lesions were hyperdense (homogeneously in 80%, peripherally in 10% and centrally in 3%); mixed density was seen in 5%, and hypodensity in 1%. In the portal phase, 4% of lesions were hyperdense (homogeneously in 1% and centrally in 3%); mixed density was seen in 11%, and hypodensity in 85%. In the delayed phase, the lesions appeared mixed in 11% of cases and hypodense in 89%. CONCLUSIONS: Spiral CT scanning of small HCCs requires dedicated and meticulous technique. Multipassage assessment is mandatory, with 2 or 3 dynamic acquisitions of the whole liver. No major difference in nodule detection was demonstrated between these two options and thus the choice rests with the radiologist's preference. Early CT images proved best for lesion detection, followed by delayed, venous, and baseline studies; lesion recognition depends largely on nodular diameter. The same applies to conspicuity, which however depends on tumor volume less. Lesion patterns are quite typical and constant in all phases and are independent of lesion diameter.     

Helical computed tomography of liver injuries: A trial of dual phase imaging

This study was performed to evaluate whether consecutive arterial phase and portal venous phase scans of the upper abdomen are contributory in the evaluation of the liver in patients with blunt abdominal trauma. The purpose of the study was to determine whether such dual acquisition using helical computed tomography (HCT) provides improved definition of injuries and significant information about the dynamics of posttraumatic hemorrhage.During a 10-month period, all patients referred for evaluation of blunt abdominal trauma were scanned using a dual phase imaging technique. Two consecutive and comparable scan clusters were programmed to study the upper abdomen, with a slice collimation of 10 mm and a 11 pitch. Intravenous contrast medium was delivered at a rate of 2 ml/sec for a total of 125 ml, with scan delays of 30 and 70 seconds (arterial and venous phases of hepatic enhancement).Thirty-two patients with hepatic lacerations were encountered, and the images from both acquisitions were compared and graded according to lesion conspicuity. The presence of contrast medium extravasation associated with parenchymal injuries was also recorded.In 23 (72%) of the 32 patients, the liver injuries were better defined in the portal venous phase, and in eight (25%) patients, the lesions were equally shown in both phases. In only one case, the lesion was better demonstrated in the arterial phase. Contrast medium extravasation was noted in two patients at the site of liver laceration. In three additional cases, contrast medium extravasation was also noted in associated splenic injuries. In all of these patients, the extravasation (bleeding laceration) was seen only in the images corresponding to the portal venous phase.Dual phase HCT of the upper abdomen does not provide significant additional information in the evaluation of patients with liver injuries resulting from blunt abdominal trauma. With a single scan cluster through the upper abdomen after a 70-second injection-scan delay, lesion definition is optimal, and vascular opacification remains adequate.     

肝局灶性结节增生的多种影像学表现分析

目的分析肝局灶性结节增生(FNH)的CT、DSA及18FDG正电子发射体层摄影术(PET)的影像表现,认识FNH的多种影像学特征.资料与方法 10例FNH经手术病理证实,回顾分析其多种影像学表现.10例均行CT平扫及动态增强扫描,其中4例行DSA肝动脉造影,2例行18FDG PET显像.结果 10例FNH均为单发性结节,位于肝右叶8例,肝左叶2例.肿瘤直径1.1～9.3 cm,平均5.1 cm.CT检查10例,平扫均为低密度,其中8例病灶(直径均＞3.0 cm)中央区有星芒状的更低密度区;增强扫描,动脉期9个结节明显强化,1个中等强化,病灶中央更低密度区无强化,2个病灶中央或周边见增粗迂曲血管,其中1个尚可见动脉-门脉、动脉-静脉分流现象;门脉期病灶密度稍有下降,8个高于或等于肝实质,2个低于肝实质;延迟期7个等于或略高于肝实质,3个低于肝实质,5个病灶中央更低密度有强化.血管造影:4例FNH的供血动脉均来自肝动脉系统,供血动脉增粗、扭曲, 1例血管分支放射状分布,周围呈环绕状聚集染色,中央局限性缺损,另3个分支血管紊乱并呈抱球征,1个尚见动脉-门脉、动脉-静脉分流.2例18FDG PET显像均未见异常放射性浓聚.结论 FNH CT平扫为低密度,增强扫描以"快进慢出"为主要特征,而血管造影显示肝动脉供血为主,表现为供血动脉增粗、扭曲,呈轮辐状向周围发散.这些影像特征有利于FNH的定性诊断.     

MSCT对肝硬化中非肿瘤性APS的诊断探讨

目的 探讨MDCT对肝硬化中非肿瘤性肝动脉门静脉分流(APS)的诊断价值. 资料与方法 对照数字减影血管造影术(DSA)结果 分析23例肝硬化患者的MDCT增强扫描及多平面重组(MPR)图像的表现. 结果 23例患者中发现28个APS灶,在动脉期均显示为高密度,门脉期为等密度,24个位于肝包膜下.在CT横断面上13个病灶表现为楔形或不规则形,另外15个虽表现为小结节样病灶但在MPR图像上13个也表现为楔形或不规则形.26个病灶DSA表现为门脉小分支早期显影,另2个DSA表现未见异常. 结论 肝硬化患者的MDCT增强扫描动脉期显示肝脏周边较小的楔性、结节样或不规则形高密度灶而在门脉期呈等密度提示非肿瘤性APS.     

细菌性肝脓肿早期CT与MRI诊断现状及进展

在肝脓肿早期影像诊断中,CT增强扫描动脉期可能出现肝一过性密度（衰减）差异,静脉期"花簇征"或"蜂窝征",延迟期"逐渐充填征",为诊断该病的可靠征象;在肝动脉灌注成像（hepatic arterial perfusion,HAP）上,脓肿病变区及脓肿邻近区呈明显高灌注,脓肿内坏死区无灌注。肝脓肿在MRI平扫T₂WI上表现为高信号,而在T₁WI上为稍低信号;增强扫描动脉期可出现一过性强化信号,静脉期、延迟期与CT表现相似;在扩散加权成像（diffusionweighted imaging,DWI）上,脓肿未完全液化时表观扩散加权系数（apparent diffusion coefficient,ADC）值相对较低,DWI表现为高信号;灌注成像表现为时间-信号曲线（time-signal curve,TSC）呈速升-缓升型式。