Sparing of fatty infiltration around focal hepatic lesions in patients with hepatic steatosis: sonographic appearance with CT and MRI correlation

OBJECTIVE: The purposes of this study were to illustrate the sonographic features of focal hepatic lesions with peritumoral sparing of fatty infiltration in patients with hepatic steatosis, to correlate the sonographic findings with CT and MRI findings, and to discuss the possible mechanisms. CONCLUSION: Various focal hepatic lesions can accompany peritumoral sparing of fatty infiltration in patients with hepatic steatosis, and they can manifest with an atypical sonographic appearance.     

Peritumoral fat-spared area is well correlated with the presence of temporal peritumoral enhancement in hepatic hemangioma in fatty liver

PURPOSE: To assess the relationship between temporal peritumoral enhancement and peritumoral focal fat sparing adjacent to hepatic hemangiomas. MATERIALS AND METHODS: On the basis of MRI and sonographic imaging follow-up, 51 hepatic hemangiomas were identified in 37 patients, who had both hepatic hemangiomas and focal fat-sparing areas in fatty liver. Among them, 36 tumors were associated with peritumoral focal fat spares. The association between the temporal peritumoral enhancement in the early arterial phase of dynamic MRI and peritumoral fat sparing in the same hemangioma was investigated. Furthermore, the configuration of the temporal peritumoral enhancement was correlated with that of the peritumoral focal fat-sparing area. We used Chi square and Fisher's exact test for statistic analysis. RESULTS: A total of 31 out of 36 hemangiomas (86.1%) showed both peritumoral focal fat spares and temporal peritumoral enhancement. The presence of temporal peritumoral enhancement is significantly related to that of peritumoral focal fat-sparing (P < 0.001). A total of 21 of the 31 tumors (67.7%) presented with similar configuration of the peritumoral focal fat-sparing area and temporal peritumoral enhancement area with respect to size and shape. The remaining 10 hemangiomas showed similar shape but slightly different size in these two imaging characteristics. CONCLUSION: Temporal peritumoral enhancement seen in hepatic hemangioma might be related to focal fatty sparing adjacent to the hemangiomas.     

Foci of eosinophil-related necrosis in the liver: imaging findings and correlation with eosinophilia

OBJECTIVE: The purpose of our study was to describe CT and sonographic findings of foci of eosinophil-related hepatic necrosis and to correlate those findings with eosinophil counts in the peripheral blood. MATERIALS AND METHODS: We retrospectively reviewed 17 helical CT and 16 sonographic examinations (including follow-up examinations) in 10 patients with pathologically proven foci of eosinophil-related necrosis. Underlying causes were anisakiasis (n = 2), malignant neoplasms (n = 3), hypereosinophilic syndrome (n = 3), and idiopathic (n = 2). CT and sonographic images were reviewed by consensus by three radiologists, with an emphasis on the morphology and distribution of foci. Imaging findings were correlated with eosinophil counts in the peripheral blood. RESULTS: All foci of eosinophil-related necrosis were observed as focal hypoattenuating lesions on all phases of helical CT and as focal hypoechoic lesions on sonography. Foci varied in size and were round or oval. The number of these foci seemed to be in proportion to the percentage of eosinophils in the peripheral blood. Most foci showed interval regression on follow-up CT or sonography as peripheral blood eosinophil counts decreased. CONCLUSION: Foci of eosinophil-related necrosis cause focal hepatic lesions of varying size, shape, and number on helical CT and sonography. The number and extent of these foci were closely correlated to eosinophil counts in the peripheral blood.     

Computed tomography and sonographic findings of hepatic metastases from gastrointestinal stromal tumors after chemotherapy

OBJECTIVE: The purpose of this study was to evaluate the computed tomography (CT) and sonographic findings in patients with hepatic metastases from gastrointestinal stromal tumors (GISTs) after STI-571 treatment. METHODS: Computed tomography and sonographic findings of 8 lesions in 6 patients with hepatic metastases from GISTs that were treated with STI-571 were retrospectively analyzed. The change in size, attenuation, and echogenicity of the hepatic metastases from GISTs after STI-571 treatment was evaluated. RESULTS: After treatment with STI-571, the hepatic metastases were decreased in size and the attenuation of the hepatic metastases was homogeneously hypodense on CT. Sonography revealed the hepatic metastases to be centrally cystic with a thin wall (n = 4) or predominantly solid (n = 4) after STI-571 treatment. On color Doppler sonography, no blood flow was identified within the solid portion of the mass. CONCLUSION: After treatment with STI-571, although the hepatic metastases from GISTs exhibit a cystic appearance on CT, they may appear as solid masses on sonography.     

Fatty metamorphosis in hepatocellular carcinoma: radiologic features in 10 cases

We describe the sonographic, CT and angiographic findings in 10 cases of hepatocellular carcinoma in which extensive fatty metamorphosis occurred within the tumors. Fatty change was diffuse in smaller tumors (less than 3.5 cm) and focal in larger tumors (greater than 3.5 cm). Fatty metamorphosis characteristically caused a low-attenuation area on CT (less than -10 H) and a highly echogenic area on sonography. The sonographic appearance of small hepatocellular carcinomas with fatty metamorphosis was identical to the findings in cavernous hemangioma or focal fatty change of the liver. CT correctly revealed the presence of fat in these hepatocellular carcinomas. In these cases, hepatic arteriography showed no tumor stain; however, CT arteriography (dynamic CT during injection of contrast medium into the hepatic artery) was useful in showing the tumor, its capsule, and its internal septa. In the diagnosis of large hepatocellular carcinoma, the presence of intratumoral fat is not likely to be problematic, but small tumors that are diffusely infiltrated by fat must be distinguished from such benign conditions as focal fatty change, lipoma, and angiomyolipoma.     

Benign liver lesions: implications of detection in cancer patients

A review of liver sonograms obtained for cancer patients (excluding primary liver cancers) over a 12 year period found 829 benign lesions: non-parasitic cysts (427 cases), hemangiomas (216 cases), solitary calcifications (79 cases), focal fatty infiltration (62 cases), and miscellaneous lesions (45 cases). These benign pathologies represented 41.8% of the focal hepatic lesions observed during this period in this population; hepatic metastases accounted for the remaining 58.2%. Marked female predilection was noted for the nonparasitic cysts, hemangiomas, and focal fatty infiltration; 63–78.7% of these lesions were solitary, and first-line imaging by US was sufficient for diagnosis of 66.1–98.2% of cases. Analysis of lesion evolution over more than 5 years revealed modifications in 17% of hemangiomas, 23.9% of nonparasitic cysts, and 75% of cases of focal fatty infiltration. Systematic pretherapy liver sonography can be proposed owing to the high frequency of benign liver lesions that can create diagnostic problems during follow-up of cancer patients. Correspondence to: J. N. Bruneton     

Contrast-enhanced second-harmonic sonography in the detection of pseudocapsule in renal cell carcinoma

OBJECTIVE: Our purpose was to assess the capacity of contrast-enhanced second-harmonic sonography to detect a pseudocapsule in renal masses compared with conventional gray-scale sonography. SUBJECTS AND METHODS. Thirty-two patients with 40 renal masses suspicious for renal cancer (mean diameter, 3.1 cm) were prospectively studied with contrast-enhanced second-harmonic sonography during IV administration of a second-generation sonographic contrast agent. The sonographic criteria for the presence of a pseudocapsule were a peritumoral hypoanechoic halo on conventional gray-scale imaging and a rim of perilesional enhancement, increasing in the tardive phase of the examination, on contrast-enhanced second-harmonic imaging. Multiphasic helical CT or dynamic MRI or both were performed in all patients. RESULTS: Final diagnoses of the 40 renal masses were as follows: hemorrhagic cysts, five; angiomyolipomas, four; lymphomas, four; metastasis from lung cancer, one; and renal cell carcinomas (RCCs), 26. Histologic diagnosis of RCC was surgically obtained in all patients. Nephron-sparing surgery was performed in 12 of 26 RCCs, and radical nephrectomy was performed in the remaining 14. At pathologic examination, pseudocapsule was found in 14 (53.8%) of 26 RCCs. On conventional sonography, the presence of a pseudocapsule was detected in 3 of 14 RCCs (sensitivity, 21%). Sonographic contrast-enhanced harmonic imaging revealed the presence of pseudocapsule in 12 of 14 RCCs (sensitivity, 85.7%). In the remaining 12 RCCs with either absent or extensive neoplastic infiltration of pseudocapsule seen at pathologic evaluation, pseudocapsule was not visible on either conventional or contrast-enhanced second-harmonic sonography. The pseudocapsule was not visible in any of the 14 noncancerous renal masses on either conventional or contrast-enhanced sonography. CONCLUSION: Sonographic contrast-specific imaging with a second-generation contrast agent is effective in improving the sonographic visualization of tumoral pseudocapsule. This finding could be useful both in the sonographic diagnosis and in the choice of conservative surgery for renal cell carcinoma. The potential role of second-harmonic contrast-enhanced sonography in the management of renal cell carcinoma should be investigated in larger series and compared with the findings of state-of-the-art MRI and CT.     

Anechoic halo in solid liver tumors: sonographic, microangiographic, and histologic correlation

The origin of the sonographic halo sign in liver metastases was studied after autopsy in 33 livers with macroscopic tumoral involvement. For 20 lesions a detailed comparison of findings from high-resolution 7.5- and 10-MHz sonography, microangiography, and histology was carried out. Histologic study focused on the tumor periphery and its relationship to the adjacent liver parenchyma. In particular, the type of tumor infiltration, the presence or absence of peritumoral fibrosis, and the degree of liver cell compression were assessed. In all but two cases the halo was extratumoral and was caused by peritumoral liver cell compression. In the remaining two cases the halo was tumoral and was caused by irregular fibrosis or vascularization.     

Role of scintigraphy in focally abnormal sonograms of fatty livers

Fatty infiltration of the liver may cause a range of focal abnormalities on hepatic sonography which may simulate hepatic nodular lesions. Discrete deposits of fat or islands of normal tissue which are uninvolved by fatty infiltration may stand out as potential space-occupying lesions on the sonograms. Twelve patients with such focally abnormal ultrasound images were referred for liver scintigraphy with 133Xe and 99mTc colloidal SPECT studies to clarify the issue. These examinations helped identify, in nine of 12 patients, the innocent nature of the sonographic abnormalities which were simply related to the fat deposition process. Further, [99mTc]RBC scans defined the additional pathologic process in three patients in whom actual space-occupying lesions were indeed present in the liver. Scintigraphy has an important role to play in the understanding of focal hepatic ultrasound abnormalities particularly in unsuspected hepatic steatosis.     

Patterns of contrast enhancement of benign and malignant hepatic neoplasms during bolus dynamic and delayed CT

Bolus dynamic and delayed computed tomographic (CT) scans of the liver were evaluated in 43 patients with 54 hepatic hemangiomas and 111 patients with primary or secondary malignant hepatic neoplasms. Twelve patterns of contrast enhancement were recognized during the bolus dynamic phase and delayed scanning. A "typical" CT pattern for hemangiomas (present in 29 of 54 hemangiomas [53.7%]) was established: (a) diminished attenuation prior to intravenous contrast medium administration (excluding lesions arising in a liver with diffuse fatty infiltration), (b) peripheral contrast enhancement during the bolus dynamic phase, and (c) complete isodense fill-in on delayed scan images. Using these criteria, we distinguished hemangiomas from malignant neoplasms in most patients. Only one of 63 (1.6%) malignant neoplasms manifested these typical CT criteria of hemangioma. There is an 86% chance that a lesion with the typical CT appearance of hemangioma is actually a hemangioma, even when found in a patient with a known nonhepatic primary neoplasm.     

Low mechanical index contrast-enhanced sonographic findings of pyogenic hepatic abscesses

OBJECTIVE: Low mechanical index contrast-specific sonography is a new technique that uses the harmonic capabilities of second-generation contrast agents to produce real-time contrast-enhanced gray-scale images. We describe the contrast-specific sonographic findings of pyogenic hepatic abscesses. CONCLUSION: Contrast-specific sonography was used to assess eight cases of aspiration-confirmed pyogenic liver abscesses. All cases were correlated with multiphasic helical CT findings. Continuous sonographic exploration allowed recognition of morphologic details not detectable on CT images. Contrast-specific sonograms showed features including rim enhancement, arteries along abscess margins and internal septa, dense and persistent septal enhancement, absent microcirculation in fluid and necrotic components, transient arterial phase hypervascularity around abscesses, and portal phase hypovascularity around abscesses. This constellation of findings is suggestive of liver abscess.     

Duplex Doppler sonography of the hepatic vein in tricuspid regurgitation

Patients with tricuspid regurgitation may present initially with vague abdominal symptoms and elevated liver enzymes. In the absence of diagnostic sonographic findings, patients may be subjected to an unnecessary invasive liver biopsy for an accurate diagnosis. We recently described the association of the pulsatile portal venous waveform on duplex Doppler sonography with tricuspid regurgitation in 15 patients. In this study I describe the changes in the hepatic venous waveform in these patients and compare the findings with the final diagnosis as determined by Doppler echocardiography (n = 14) or ultrafast CT (n = 1). All patients had clinical findings consistent with liver dysfunction and were referred for sonography to rule out diseases of the liver, biliary tree, or hepatic or portal veins. All patients had persistently dilated hepatic veins and inferior venae cavae. Twenty-four volunteers, 11 of whom had simultaneous ECG tracings, served as a control group. The main findings on the hepatic duplex sonogram in the disease group were a decrease in the size of the antegrade systolic wave with a systolic/diastolic flow velocity ratio of less than 0.6 (n = 4) or reversal of the systolic wave (n = 10). In all volunteers, systolic flow was antegrade and the ratio was more than 0.6. Two diagnoses were false positive and one was false negative. In some patients with sonographic signs of congestive heart failure, duplex Doppler sonography of the hepatic vein may be helpful in the diagnosis of one of the causes of liver dysfunction, tricuspid regurgitation.     

Focal fatty change of the liver adjacent to the falciform ligament: CT and sonographic findings in five surgically confirmed cases

Five cases of surgically confirmed focal fatty infiltration of the liver were detected by CT and sonography. In all five cases, the abnormality was located at the anterolateral edge of the medial segment of the liver. It was seen as a small area of low attenuation adjacent to the falciform ligament on CT and as an echogenic area next to the ligamentum teres on sonography. Dynamic CT performed during infusion of contrast medium via the superior mesenteric artery (arterial portography) showed portal blood flow within the lesion and was useful for excluding the presence of a hepatic tumor. Focal fatty infiltration of the liver adjacent to the falciform ligament constitutes a diagnostic pitfall on CT and sonography.     

Sonography of diabetic muscle infarction with MR imaging, CT, and pathologic correlation

OBJECTIVE: The purpose of this article is to describe the sonographic findings of muscle infarction in patients with diabetes with MR imaging, CT, and pathologic correlation. CONCLUSION: Sonographic findings of diabetic muscle infarction include internal linear echogenic structures coursing through the lesion; an absence of internal motion or swirling of fluid with transducer pressure; and a lack of a predominately anechoic area. We believe that these sonographic characteristics may help differentiate diabetic muscle infarction from abscess or necrotic tumor. Additional study involving direct sonographic comparison of these entities is needed to establish the role of sonography in diagnosis of diabetic muscle infarction.     

Sonography in a clinical algorithm for early evaluation of 1671 patients with blunt abdominal trauma

OBJECTIVE: The purpose of this study was to evaluate the efficacy of sonography in our algorithm when differentiating patients with blunt abdominal trauma who need immediate surgery from patients who would benefit from further diagnostic workup or who need no treatment. SUBJECTS AND METHODS: We performed abdominal sonography as the primary screening tool in 1671 consecutive patients in our prospective study. Radiologists performed sonography in the trauma room within minutes of the arrival of each patient. Hemodynamic instability in conjunction with positive sonographic findings led to emergency laparotomy. Otherwise, positive sonographic findings warranted additional diagnostic tests. Observing free fluid or organ injury caused us to categorize sonographic findings as positive. RESULTS: Sonography correctly identified all patients requiring emergency laparotomy. No inconclusive laparotomies were performed in this group. The sensitivity of sonography for revealing intraabdominal injury was 88%, the specificity was 100%, and the accuracy was 99%. In 132 patients (8%), abdominal CT was performed. CT revealed relevant posttraumatic abnormalities in 61% of all patients. Four hundred seventy patients with negative sonographic findings were discharged approximately 12 hr after admission; two of these patients (0.4%) were mistakenly discharged. Trauma scores did not influence the efficacy of sonography. CONCLUSION: Our algorithm that uses sonography as the primary diagnostic tool provides accurate, fast, cost-effective, and noninvasive initial management of patients with blunt abdominal trauma. Our test characteristics were excellent indicators of the need for emergency laparotomy. Sonography also achieves high values in revealing relevant injury. Our algorithm produced medically satisfactory and economically prudent management of patients with blunt abdominal trauma.     

The hyperechogenic liver in children: cause and sonographic appearance

The clinical records of 28 patients seen in one institution during a recent 2 year period who, on sonography, had been identified as having a hyperechogenic (bright) liver were reviewed. Seven children were diagnosed as having metabolic diseases, four were malnourished, four were receiving hyperalimentation, 10 were receiving chemotherapy, and three were undiagnosed. The sonograms of all the patients and the histologic sections on those who had biopsies, were reevaluated in order to assess the sonographic pattern in greater detail, and these findings were correlated with fatty infiltration and fibrosis of the liver. The bright liver corresponded to the pathologic finding of fatty change. This sonographic finding in children is important, as further evaluation (hepatic biopsy with fat stain, enzymatic analyses, amino acid screens) can be suggested to identify underlying metabolic disorders in those not on therapy. Often the complications of metabolic diseases can be prevented or delayed by early diagnosis and appropriate therapy.     

Imaging of atypical hemangiomas of the liver with pathologic correlation.

Compared with the imaging features of typical hepatic hemangiomas, the imaging features of atypical hepatic hemangiomas have not been well studied or well described. Knowledge of the entire spectrum of atypical hepatic hemangiomas is important and can help one avoid most diagnostic errors. A frequent type of atypical hepatic hemangioma is a lesion with an echoic border at ultrasonography. Less frequent types are large, heterogeneous hemangiomas; rapidly filling hemangiomas; calcified hemangiomas; hyalinized hemangiomas; cystic or multilocular hemangiomas; hemangiomas with fluid-fluid levels; and pedunculated hemangiomas. Adjacent abnormalities consist of arterial-portal venous shunt, capsular retraction, and surrounding nodular hyperplasia; hemangiomas can also develop in cases of fatty liver infiltration. Associated lesions include multiple hemangiomas, hemangiomatosis, focal nodular hyperplasia, and angiosarcoma. Types of atypical evolution are hemangiomas enlarging over time and hemangiomas appearing during pregnancy. Complications consist of inflammation, Kasabach-Merritt syndrome, intratumoral hemorrhage, hemoperitoneum, volvulus, and compression of adjacent structures. In some cases, such as large heterogeneous hemangiomas, calcified hemangiomas, pedunculated hemangiomas, or hemangiomas developing in diffuse fatty liver, a specific diagnosis can be established with imaging, especially magnetic resonance imaging. However, in other atypical cases, the diagnosis will remain uncertain at imaging, and these cases will require histopathologic examination.     

Hepatic cavernous hemangioma: temporal peritumoral enhancement during multiphase dynamic MR imaging

PURPOSE: To determine whether temporal parenchymal enhancement around hepatic cavernous hemangiomas can be correlated with the rapidity of intratumoral contrast material enhancement and/or tumor volume at dynamic magnetic resonance (MR) imaging. MATERIALS AND METHODS: Dynamic MR images obtained in 94 patients with 167 hemangiomas were retrospectively reviewed for peritumoral enhancement. Tumor volume was estimated by using the longest dimension on nonenhanced images. Speed of intratumoral contrast material enhancement was determined with early nonequilibrium phase images and was categorized as rapid (>75% of tumor volume), intermediate (25%-75% of tumor volume), or slow (<25% of tumor volume). RESULTS: Thirty-two of the 167 hemangiomas (19%) had temporal peritumoral enhancement, which was more common in hemangiomas with rapid enhancement (20 of 49 [41%]) than in those with intermediate (12 of 62 [19%]) and slow (0 of 56 [0%]) enhancement (P: <.001). The mean diameter of the hemangiomas with peritumoral enhancement was not significantly different from that of hemangiomas without peritumoral enhancement (P: >.05). Hemangiomas with rapid enhancement (mean diameter, 16 mm +/- 8), however, were significantly smaller than those with intermediate enhancement (mean diameter, 33 mm +/- 34) (P: <.001). CONCLUSION: Temporal peritumoral enhancement on dynamic MR images of hepatic hemangiomas correlates well with the speed of intratumoral contrast material enhancement and was most commonly encountered in rapidly enhancing small lesions. There was no statistically significant relationship, however, between peritumoral enhancement and tumor volume.     

Phase-inversion sonography during the liver-specific late phase of contrast enhancement: improved detection of liver metastases

OBJECTIVE: The purpose of our study was to assess whether phase-inversion sonography during the late, liver-specific phase of contrast enhancement using Levovist improves the detection of hepatic metastases relative to unenhanced conventional B-mode sonography. SUBJECTS AND METHODS: Sixty-two patients were studied with unenhanced B-mode sonography and phase-inversion sonography 2.5 min after the injection of Levovist. All patients underwent one reference examination (CT, MR imaging, or intraoperative sonography). The conspicuity, number, size, and distribution of metastases before and after contrast administration as judged by a sonographer (who was unaware of other imaging findings) were compared with each other and with reference imaging. RESULTS: The conspicuity of metastases was improved by contrast-enhanced phase inversion in 94% of patients. Thirty-nine patients showed metastases on reference imaging; 36 of these were positive on baseline sonography and 38 on phase-inversion sonography. Phase-inversion sonography showed more reference imaging-confirmed metastases than baseline sonography in 28 patients (45%). The average number of confirmed metastases per patient was 3.06 for baseline sonography and 5.42 for contrast-enhanced phase-inversion sonography (p < 0.01). The average sensitivity for detecting individual metastases improved from 63% to 91%. Metastases of less than 1 cm were shown in 14 patients on baseline sonography, in 24 patients on phase-inversion sonography, and in 26 on reference imaging. Both sonographic techniques showed false-positive lesions in six patients. CONCLUSION: Contrast-enhanced phase-inversion sonography in the liver-specific phase of contrast enhancement using Levovist provides a marked improvement in the detection of hepatic metastases relative to unenhanced conventional sonography, without loss of specificity. Phase-inversion sonography was particularly advantageous in detecting small metastases and may be a competitive alternative to CT and MR imaging.     

Temporal peritumoral enhancement of hepatic cavernous hemangioma: findings at multiphase dynamic magnetic resonance imaging

OBJECTIVE: To evaluate the occurrence rate of temporal peritumoral enhancement associated with hepatic cavernous hemangiomas and to correlate that with the speed of intratumoral contrast enhancement and tumor volume. METHODS: Dynamic magnetic resonance imaging (MRI) of 69 consecutive patients with 136 hemangiomas was reviewed for peritumoral enhancement. Tumor volume was estimated by the largest diameter on T2-weighted images. Speed of intratumoral contrast enhancement was determined by portal phase image and was categorized as rapid (>75% of tumor volume), intermediate (25%-75% of tumor volume), or slow (<25% of tumor volume). RESULTS: Temporal peritumoral enhancement was found in 37 (26.6%) of 136 hemangiomas. It was more common in hemangiomas with rapid enhancement (30 of 67 cases [44.8%]) than in those with intermediate (3 of 22 cases [13.6%]) and slow (4 of 47 cases [8.5%]) enhancement (P < 0.05). There was no statistically significant relation between lesion size and presence of temporal peritumoral enhancement (P > 0.05). CONCLUSIONS: Temporal peritumoral enhancement is not uncommonly seen in hepatic cavernous hemangiomas at dynamic MRI. It is most commonly encountered in rapidly enhancing small lesions. There is no statistically significant relation between temporal peritumoral enhancement and tumor volume, however.