Focal nodular hyperplasia and hepatocellular adenoma of the liver: differentiation with multiphasic helical CT

OBJECTIVE: Differences of attenuation and enhancement patterns in focal nodular hyperplasia and hepatocellular adenoma were evaluated and quantified using triphasic single-slice helical CT. MATERIALS AND METHODS: Forty-five histologically proven focal nodular hyperplasias in 27 patients and 18 hepatocellular adenomas in six patients were examined with helical CT. Quantitative evaluation included the following: attenuation of lesions, scar, and liver parenchyma during unenhanced, arterial (20 sec after injection), and portal venous phases (70 sec after injection); relative enhancement of lesions and liver (the ratio between attenuation in arterial phase and portal venous phase, respectively, and attenuation in unenhanced phase); and the prevalence of scar and its central vessel in focal nodular hyperplasia. RESULTS: The study showed no significant difference between mean attenuation values of focal nodular hyperplasia (mean +/- SD, 51.2 +/- 5.9 H) and hepatocellular adenoma (mean +/- SD, 56.3 +/- 7.8 H) in the unenhanced phase. In the arterial phase attenuation values were significantly higher in focal nodular hyperplasia (mean +/- SD, 117.9 +/- 15.1 H) than in hepatocellular adenoma (mean +/- SD, 80.1 +/- 10.5 H). In the portal venous phase no significant differences in attenuation values were detected between focal nodular hyperplasia (mean +/- SD, 112.1 +/- 20.4 H) and hepatocellular adenoma (mean +/- SD, 110.2 +/- 12.9 H). For enhancement parameter thresholds separating focal nodular hyperplasia from hepatocellular adenoma, the following were found: the relative enhancement was higher in 100% of the focal nodular hyperplasias and lower than or equal to 1.6 (accuracy, 96%) in 87% of the hepatocellular adenomas. CONCLUSION: Triphasic helical CT combined with quantitative evaluation of liver lesions offers the possibility of detecting differences in liver lesions that are visually similar on CT. The attenuation and relative enhancement in the arterial phase show significant differences that make accurate differentiation between focal nodular hyperplasia and hepatocellular adenoma possible.     

肝脏炎性假瘤的影像学诊断现状与进展

肝脏炎性假瘤(IPL)是一种少见的良性肿瘤样病变，其影像学表现多样化。超声检查：表现为低回声不均质结节，形态不规则，后方无声能衰减现象。彩色多普勒血流显像(CDFl)多无明确彩色血流信号。CT检查：平扫表现为低密度灶；增强扫描，多数病例动脉期不强化，门静脉期及延迟期可呈现多种强化方式，表现为周边环形强化、整个病灶不均匀强化、病灶内结节状强化及肿块周边和内部高密度分隔等。炎症过程的动态变化及不同程度的纤维组织增生、炎性细胞浸润、凝固坏死是产生多种强化类型的病理基础。MRI检查：由于病灶病理阶段的不同，平扫中T1WI及T2WI信号强度不一，可表现为长T1、长T2或长T1、等T2信号。GD-DTPA增强扫描部分病灶动脉期可见快速明显强化，门静脉期及延迟扫描强化方式与CT增强扫描大致相同。肝脏特异性对比剂增强扫描病灶无明显强化。     

肝脏局灶性结节增生的螺旋CT和MRI诊断

目的 :分析肝脏局灶性结节增生 (FNH)平扫和动态增强的螺旋CT、MRI表现 ,提高FNH诊断符合率。方法 :对 13例经手术病理证实的FNH影像学表现进行回顾性分析。螺旋CT检查 8例 ,MRI检查 6例 ,其中 1例同时做CT和MRI检查。结果 :8例CT平扫病灶均呈低密度 ,均匀或不均匀。增强动脉期扫描除中心疤痕外 ,所有病灶均有明显均匀强化 ,其中 4例还可见到病灶中心或周边增粗、扭曲的动脉。门脉期和延迟期扫描 4例呈略高密度、4例病灶呈等密度或略低密度 ,4例伴有中心疤痕者均有延迟强化。MRI检查 6例 ,病灶均呈不均匀略长或等T1及T2 信号 ,增强动脉期呈明显强化 ,门脉期及延迟期呈等或略高强化 ,4例MRI平扫显示中央瘢痕者有延迟强化。结论 :平扫和动态增强螺旋CT、MRI能较全面显示FNH的病理特征和血供特点 ,明显地提高与其它富血管恶性肿瘤的鉴别诊断能力     

Long-term follow-up of hepatitis using computed tomography

Computed tomography of the liver was performed on two patients with subacute hepatitis. The CT findings included the presence of multiple regenerative nodules in the atrophied liver, shown by decreased CT attenuation. Complications due to hepatitis, such as massive ascites and splenomegaly, were also observed. The CT observations during the course of the disease suggested that the hepatic necrosis had been repaired by hypertrophy of regenerating nodules, not by an increase in the number of nodules, which ultimately gave rise to postnecrotic cirrhosis. Scintigraphy confirmed atrophy and repair of the liver. Thus, CT and scintigraphy were considered to be useful for the diagnosis of extensive hepatic necrosis and for evaluating the process of liver repair.     

Focal nodular hyperplasia: CT findings with emphasis on multiphasic helical CT in 78 patients

PURPOSE: To evaluate features of focal nodular hyperplasia (FNH) at multiphasic helical computed tomography (CT). MATERIALS AND METHODS: Clinical, pathologic, and preoperative imaging findings were retrospectively reviewed in 78 patients. Conventional liver CT was performed in nine patients; helical multiphasic CT, in 69. Diagnosis was based on complete resection (n = 20), biopsy (n = 42), or clinical and imaging follow-up for a minimum of 6 months (n = 16). Number, size, location, margins, surface, homogeneity of enhancement, and presence of a central scar, mass effect, exophytic growth, calcification, pseudocapsule, or vessels feeding or draining the lesion were evaluated. RESULTS: CT depicted 124 tumors (mean diameter, 4.1 cm; range, 1-11 cm); 62 were small (< or =3 cm). FNHs were hypervascular and hyperattenuating to liver on 106 of 106 arterial phase scans and were isoattenuating to liver on 82 of 89 delayed scans. Of the 124 tumors, 111 enhanced homogeneously, 109 had a smooth surface, 101 were subcapsular, 89 had ill-defined margins, and 62 had a central scar that was observed more often in large lesions (40 of 62 lesions) than in small lesions (22 of 62 lesions). FNHs less frequently exerted a mass effect (43 lesions), had vessels around or within the lesion (42 lesions), demonstrated exophytic growth (40 lesions), or showed a pseudocapsule (10 lesions). Only one FNH had calcification. CONCLUSION: Helical CT demonstrates characteristic features that may allow confident diagnosis of FNH. In typical cases, neither biopsy nor further imaging is necessary.     

螺旋CT多期扫描诊断肝脏局灶性结节增生研究

目的 探讨肝脏局灶性结节增生(FNH)的螺旋CT平扫和多期增强扫描表现特征,以提高CT对FNH的诊断准确性.资料与方法 回顾性分析16例经病理证实的FNH患者螺旋CT平扫及动脉期、门静脉期、延迟期增强扫描的资料.结果 16例患者16个FNH病灶中,平扫显示所有病灶均为略低密度,位于肝包膜下,其中14个可见更低密度瘢痕,从病灶中心向周围呈辐射状或不规则状.肿块实质呈"快进慢出"强化,中心瘢痕及辐射状分隔、假包膜"延迟强化",延迟期整个肿块密度趋于均匀一致.结论 平扫和多期增强螺旋CT扫描能全面显示FNH的病理特征及血流动力学特点,螺旋CT多期扫描有助于FNH的诊断及鉴别诊断.     

肝脏局灶性结节增生影像分析

目的 :分析肝脏局灶性结节增生 (FNH )的CT、MR及DSA表现 ,提高对本病的认识。方法 :6例经证实的FNH ,均行CT、MR及DSA检查。结果 :6例病灶CT平扫低密度者 4例 ,均匀或不均匀 ,2例为等密度。增强动脉期所有病灶均有明显强化 ,除中心瘢痕外病灶强化均匀一致 ,3例可见到中心或周边增粗、扭曲的动脉。门脉期和延迟期扫描 4例病灶为等密度 ,2例为略高密度。 3例伴有中心瘢痕 ,1例无强化 ,2例延迟强化。 2例行DSA检查 ,病灶内分布较均匀的新生血管团。MR检查 4例 ,T1 WI呈等信号或略低信号 ,T2 WI呈略高信号。 1例行Gd DTPA增强延迟期呈略高信号 ,中心瘢痕无明显强化。结论 :CT、MR及DSA检查可充分反映FNH的血供特点和病理特征 ,动态增强是诊断FNH最有效的影像学手段 ,在诊断和鉴别诊断中具有很大价值     

Imaging well-differentiated hepatocellular carcinoma with dynamic triple-phase helical computed tomography

To investigate the imaging appearance of well-differentiated hepatocellular carcinoma (HCC) on dynamic CT, a total of 38 histopathologically proven well-differentiated HCC were included in a retrospective study. We reviewed the contrast-enhanced dynamic CT of all 38 tumours for attenuation of each tumour in unenhanced scan, arterial-dominant and delayed portal venous phases. Our results showed that dynamic CT identified 26 (68.4%) out of the 38 lesions. The remaining 12 lesions were isodense compared with surrounding liver parenchyma in each dynamic CT phase. There was no statistically significant difference between the mean size of tumours detected by dynamic CT and that of tumours not detected by dynamic CT (p = 0.1). Of a total of 38 tumours, most were isodense (n = 19) or hypodense (n = 16) in unenhanced scan, mostly hyperdense (n = 18) or isodense (n = 15) in arterial-dominant phase and mostly isodense (n = 22) or hypodense (n = 15) in delayed portal venous phase. Enhancement of tumour was observed in 19 (50.0%) of 38 lesions. In conclusion, the ability of dynamic CT to detect well-differentiated HCC is poor, and negative CT findings cannot exclude the presence of well-differentiated HCC, especially if there is well-grounded clinical suspicion for HCC.     

肝局灶性结节增生的MRI诊断价值与CT征象比较

目的:评价肝局灶性结节增生(FNH)的MRI诊断价值。方法:经手术或穿刺活检病理证实的FNH19例,共21个病灶。全部病例进行了CT和MRI检查,CT检查常规行平扫和双期增强扫描;MRI平扫序列如下:用快速恢复快速自旋回波序列(FRFSE)采集压脂T2W图像,用快速扰相梯度回波序列(FSPGR)采集压脂T1W图像,用真稳态进动梯度回波序列(FIESTA)采集T2/T1比值加权图像,用FSPGR序列同时采集无脂肪抑制的反相位和同相位T1W图像。所有病例均行Gd-DTPA动态增强扫描,其中3例进行细胞特异性对比增强扫描。结果:17个FNH在平扫T2WI fs为等信号或略高信号,在T1WI fs上呈等信号或略低信号。MRI平扫共见中心瘢痕12个、中央粗大血管3条、假包膜数2个,均多于CT平扫所见。Gd-DTPA动态增强扫描时,21个FNH于动脉期均明显强化,16个FNH于门脉期或延迟期的信号强度与肝组织接近,中心瘢痕和假包膜延迟强化。行细胞特异性对比增强扫描的3个FNH实质均明显强化,中心瘢痕无强化。结论:绝大多数FNH在MRI上有特征性的征象,MRI可以明确诊断,MRI对FNH的诊断价值高于CT。     

Solid organizing hepatic abscesses mimic hepatic tumor: Multiphasic computed tomography and magnetic resonance imaging findings with histopathologic correlation

OBJECTIVE: To describe the computed tomography (CT) and magnetic resonance imaging (MRI) findings of solid organizing hepatic abscesses and correlate them with the pathologic findings. METHODS: Ten patients with 10 pathologically proven solid organizing hepatic abscesses who underwent 3-phase CT (n = 10) or MRI (n = 7) were enrolled in this study. Images were retrospectively analyzed by consensus of 2 radiologists for attenuation (signal intensity), shape, and margin of the lesions as well as for their enhancement patterns. Their imaging findings were correlated with their pathologic findings. RESULTS: The main imaging finding on CT or MRI was the well-defined target appearance of a central enhancing area with a low-attenuation (signal intensity) rim on arterial and portal phases. On the delayed phase, most of lesions showed slightly low attenuation (signal intensity) with an enhancing rim, and 1 showed diffuse enhancement. Pathologically, the central areas and peripheral rims corresponded to granulation tissue and fibrosis, respectively. Nine lesions demonstrated a tiny necrotic cystic portion in the center. CONCLUSION: The target appearance of solid organizing hepatic abscesses on CT and MRI can be helpful in differentiating them from other focal liver lesions. These imaging findings are well correlated with the pathologic findings.     

Esophageal cancer: evaluation with triple-phase dynamic CT--initial experience

PURPOSE: To prospectively assess which phase of a triple-phase dynamic contrast material-enhanced multi-detector row computed tomography (CT) protocol is optimal for visualization of esophageal cancer. MATERIALS AND METHODS: The study was supported by the local ethical committee; all patients gave written informed consent. Thirty-one lesions in 28 consecutive patients (26 men, two women; mean age, 65 years; range, 53-87 years) with histopathologically confirmed esophageal cancer were evaluated with triple-phase dynamic CT performed at 5, 35, and 65 seconds (first arterial, second arterial, and venous phases) after attenuation of 200 HU was obtained at the descending aorta. Qualitative image analysis was performed to assess appearance and conspicuity of the tumor. Appearances of all 31 lesions were classified into three categories-not identifiable, focal enhancement with or without minimal (<1 cm) wall thickening, and focal mass lesion or obvious (>1 cm) wall thickening. Results were compared with surgical or endoscopic ultrasonographic findings. Quantitative assessment included regions-of-interest measurement of the tumor and normal esophageal wall and the difference between those measurements. A paired t test was used to determine which phase showed the highest tumor attenuation and tumor-to-normal esophageal wall attenuation differences. RESULTS: At visual assessment, 30 lesions were identified in the second arterial phase. Of these 30 lesions, eight were focal enhancements; the best conspicuity was during the second arterial phase. Furthermore, seven of these eight lesions were T1 cancers. The remaining 22 lesions were enhanced masses or wall thickening. Twenty-one of these 22 tumors also showed best conspicuity in the second arterial phase. The greatest attenuation of tumors in the second arterial phase was 130.0 HU, and the difference in attenuation between tumor and normal esophageal wall was 50.6 HU in the second arterial phase, which were significantly higher than those in the other two phases (P<.01, each). CONCLUSION: The second arterial phase of dynamic CT is the optimal phase for visualization of esophageal cancer.     

Value of dual-energy CT in differentiating focal fatty infiltration of the liver from low-density masses

Focal (irregular, partial) fatty infiltration of the liver may simulate neoplastic or other hypodense masses on CT. On the basis of previous observations of the phenomenon that differences in X-ray attenuation diminish with increasing energy of X-rays used, we performed a preliminary study to determine if dual-energy CT could be used to discriminate between fatty infiltration and hypodense liver masses. Dual-energy CT at 140 and 80 kVp was performed in 14 patients undergoing liver biopsy and in seven control subjects with presumedly normal liver. Attenuation measurements were taken, and the changes in attenuation between 140 and 80 kVp were calculated. The mean changes in attenuation were 3.5 H for normal liver (n = 7), 2.5 H for hypodense liver masses (n = 6), 13 H for fatty liver (n = 5), 0.3 H for fatty liver combined with hemochromatosis or hemosiderosis (n = 3), and 2 H for the spleen (n = 18). The change in attenuation increased as the fat content in the liver increased. Analysis of variance showed a statistically significant difference (p less than .001) between fatty liver and the other groups. A difference greater than 10 H was unique to fatty infiltration. These results suggest that dual-energy CT may help to differentiate focal fatty infiltration of the liver from low-density neoplastic or other lesions, but only if the iron content of the liver is not increased.     

肝脏局灶性结节增生的MRI和MSCT征象比较

目的：比较分析肝脏局灶性结节增生（FNH）的MRI、MSCT征象,以提高对FNH影像诊断水平。方法：回顾性分析13例经手术病理证实为FNH病例的影像资料,所有病例均行MRI、MSCT检查,且两种检查间隔时间为1个月以内。结果：12例为肝内单发病灶、1例为多发（2个）病灶。病灶中79%（11/14）MRI平扫T2WI为等或稍高信号,T1WI为等或稍低信号,21%（3/14）T2WI为高信号、T1WI为低信号;所有病灶（14/14）MSCT平扫均呈等或稍低密度;同时在显示病灶内部结构时MRI中79%（11/14）、MSCT中57%（8/14）见中央瘢痕或纤维分隔。MRI及MSCT两种检查方法的动态增强中,病灶表现为动脉期实质部分明显强化的比率MRI为100%（14/14）、MSCT为93%（13/14）;病灶周边或中央异常增粗、扭曲的血管影MRI为14%（2/14）、MSCT为43%（6/14）;病灶周边假包膜MRI为21%（3/14）、MSCT为7%（1/14）;所有病灶均表现出＂快进慢出＂强化方式;中央瘢痕延迟强化MRI为82%（9/11）、MSCT为63%（5/8）。结论：绝大多数FNH在MRI和MSCT上有特征性的征象,MRI对其中央瘢痕病理特征的显示优于MSCT,MSCT则在病灶周边或中央增粗、扭曲血管病理特征的显示上优于MRI。     

Glycogen content in rat liver. Importance for CT and MR imaging

PURPOSE: CT and MR imaging are appropriate modalities for imaging of the liver. Contrast media are used to obtain a greater difference in attenuation and signal intensity, respectively, between normal liver tissue and focal lesions. However, no studies have attempted to determine whether physiological nutritional status of the liver during fasting is of importance for the native signal of normal liver tissue. MATERIAL AND METHODS: Using normal and fasting rats, we performed hepatic CT and MR imaging and glycogen analyses from excised tissue. RESULTS: A significantly higher liver attenuation in normal rats compared to fasting rats was found in CT. In MR images, there was a small but significantly lower liver signal-to-noise ratio in normal rats compared to fasting rats in T1-weighted and proton density-weighted images. Glycogen analyses showed depleted glycogen deposits in fasting rats and a mean glycogen content of 50.1 mg glucose equivalent/g liver tissue in normal rats. CONCLUSION: In CT, a normal nutritional status increases the native attenuation in normal liver tissue. The changes in attenuation in normal liver tissue correlate well with the additional attenuation of glycogen storage in the hepatocyte. The results indicate that the nutritional status is of less importance in MR imaging.     

Computed tomography attenuation measurements for the characterization of hepatic haemangiomas.

The attenuation values of 21 hepatic haemangiomas in 19 patients were measured on non-enhanced computed tomographic (CT) scans and compared with the attenuation of adjacent liver and the inferior vena cava (IVC). The attenuation of hepatic haemangiomas was lower than that of the surrounding liver, but there was no correlation between these two measurements. There was a highly significant correlation between the attenuation of haemangiomas and blood in the vena cava (r = 0.905, p less than 0.001). All the haemangiomas had attenuations within 7 HU of caval blood. By comparison, in 34 hypodense hepatic lesions that did not show contrast-enhanced appearances characteristic of haemangioma, there was no significant correlation between the attenuation of the lesions and the IVC. Nineteen (56%) of these lesions had attenuations differing more than 7 HU from that of caval blood. The influence of this observation on the requirement for dynamic contrast-medium-enhanced and delayed post-contrast CT in the assessment of hepatic lesions is discussed.     

肝脏局灶性结节增生的螺旋CT诊断

目的探讨肝脏局灶性结节增生的螺旋CT影像表现,旨在提高对该病的诊断准确性。方法经手术病理证实的肝脏局灶性结节增生19例均经螺旋CT平扫与增强扫描,对其影像特征回顾性分析。结果肝脏局灶性结节增生多发生于青壮年患者,主要分布在肝脏表面,病变边界清晰,动态增强肝动脉期病灶总体显著强化,病灶内见点状、小星状、大片放射状低密度中央瘢痕影,其中大片放射状中央瘢痕延时扫描可见轻度-中度强化。结论螺旋CT动态增强扫描对肝脏局灶性结节增生的定性诊断有较高价值。     

Nodular sarcoidosis of the liver and spleen: Appearance on MR images

Small nodular lesions in the liver and spleen have been reported as an infrequent manifestation of sarcoidosis. Five patients with this appearance on either dynamic contrast material—enhanced computed tomographic (CT) or ultrasound scans underwent magnetic resonance (MR) imaging with and without dynamic gadolinium enhancement. The lesions were relatively uniform in size, ranging from 0.5 to 1.5 cm. On CT scans, they were hypoattenuating relative to surrounding parenchyma. On MR images, the lesions were hypointense relative to background parenchyma with all sequences. No substantial enhancement was observed in the lesions, although lesion conspicuity decreased over time on serial postcontrast images. Lesion conspicuity was greatest on either T2-weighted fat-suppressed (T2FS) images or early-phase dynamic contrast-enhanced images. Abdominal adenopathy was seen in three of the five patients and was hyperintense relative to liver on T2FS images in two and intermediate in intensity in one patient.     

Computed tomography of benign hepatic tumors

Computed tomography (CT) was performed on five patients with focal benign liver lesions: two cases of focal nodular hyperplasia (FNH) and three cases of hepatic adenoma (HA). All five patients had low density lesions seen best on noncontrast scans. Focal nodular hyperplasia often presents as an asymptomatic, well circumscribed lesion with a central, stellate, fibrous scar. Hepatic adenoma, which is associated with the use of oral contraceptives, is a smooth bordered mass that exhibited foci of hemorrhage in two of our three cases. Both of these benign liver lesions enhance to a variable degree of following intravenous contrast medium administration. It is concluded that a specific diagnosis of FNH or HA may be suggested when appropriate CT findings are detected.     

小儿肝脏恶性肿瘤的CT诊断（附9例报告）

报告小儿肝脏恶性肿瘤９例（原发性７例）其中肝母细胞瘤３例，肝细胞癌４例；转移性２例）。原发性肝脏恶性肿瘤的ＣＴ征象为：（１）平扫肝实质内单个或多个低密度肿块，增强扫描病灶不均质增强；（２）大多数肿瘤较大，常使肝脏变形；（３）肿瘤通常累及肝脏一叶，右叶多见，但可以累及两叶或多中心；（４）胸部是最常见的转移部位。分析和讨论了肝母细胞瘤和肝细胞癌之间的鉴别诊断。转移性肝脏肿瘤平扫显示为单个或多个边界清楚的低密度病灶，增强扫描更清楚地显示之，但其表现无特异性。     

Telangiectatic focal nodular hyperplasia: US,CT, and MR imaging findings with histopathologic correlation in 13 cases

PURPOSE: To review the ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) imaging findings in 13 patients with telangiectatic focal nodular hyperplasia (FNH) and to compare imaging features with histopathologic results from resected specimens. MATERIALS AND METHODS: US, helical multiphasic CT, and MR images in 13 patients with pathologically proven telangiectatic FNH were reviewed retrospectively. Two abdominal radiologists evaluated lesions for number, size, heterogeneity, surface characteristics, presence of a central scar, presence of a pseudocapsule, US appearance, attenuation at CT, signal intensity at MR imaging, and presence of associated lesions. Imaging and pathologic findings were compared. RESULTS: Sixty-one lesions (5-140 mm in diameter) were seen at imaging. Lesions were multiple in eight of 13 (62%) patients. Imaging characteristics were heterogeneity in 26 of 61 lesions (43%), well-defined margins in 43 of 61 (70%), lack of a central scar in 56 of 61 (92%), presence of a pseudocapsule in three of 61 (5%), hyperintensity on T1-weighted MR images in 17 of 32 (53%), strong hyperintensity on T2-weighted MR images in 24 of 54 (44%), and persistent enhancement on delayed contrast material-enhanced CT or T1-weighted MR images in 23 of 38 (61%). No specific US pattern was noted. Two patients had additional lesions: One had classic FNH, and the other had a cavernous hemangioma. Hyperintensity on T1-weighted MR images was due to sinusoidal dilatation. Hyperintensity on T2-weighted MR images correlated well with the presence of inflammation. CONCLUSION: Telangiectatic FNH differs from typical FNH at imaging: Atypical FNH features often observed with telangiectatic FNH are lack of a central scar, lesion heterogeneity, hyperintensity on T1-weighted MR images, strong hyperintensity on T2-weighted MR images, and persistent contrast enhancement on delayed contrast-enhanced CT or T1-weighted MR images.