Detection of hepatic metastases in diffuse fatty infiltration by CT: the complementary role of imaging

Six patients undergoing computed tomographic (CT) evaluation for possible abdominal and pelvic metastases were shown to have diffuse fatty infiltration of the liver and findings indeterminate for hepatic metastases. In two patients with diffuse fatty infiltration and no focal hepatic lesions on CT, technetium-99m sulfur colloid imaging demonstrated focal hepatic defects confirmed to represent metastases. In four patients with diffuse fatty infiltration and hyperdense liver foci on CT, radionuclide imaging demonstrated normal uptake in the hyperdense foci confirmed to represent areas of normal liver spared by fatty infiltration. In each of the six patients, clinical management was altered by the radionuclide findings.     

Focal sparing around the gallbladder in fatty liver: an useful sign in the diagnosis of borderline cases by CT

The role of CT in the diagnosis of fatty liver is well established. CT has been proved to be a useful noninvasive tool for the demonstration of fatty infiltration of the liver. The characteristic finding is a diffuse decrease in the attenuation within the liver compared with that of the spleen. Commonly, fatty infiltration of the liver is generalized and both CT scans and sonograms can easily demonstrate changes related to this condition. Sometimes, fatty infiltration of the liver is focal and occasionally, it is generalized with focal sparing of the normal liver tissue creating some problems in the diagnosis. Recently, some reports have mentioned the appearance of a focal sparing area in the generalized fatty liver. We often found a high attenuation region around the gallbladder bed in the fatty liver patients on CT examination. There appears to be some relationship between the high density around the gallbladder area and the fatty liver. A retrospective study was undertaken to evaluate the relationship. In this paper, we presented the CT scans of 57 fatty liver cases and compared them with the CT scans of 50 normal patients to discuss the possible cause of the phenomenon and its usage in the diagnosis of the fatty liver.     

Reversible fatty infiltration of the liver parenchyma in acute pancreatitis

Case studies show that acute pancreatitis occurring independently or combined with a preceding abuse of alcohol may be the cause of fatty infiltration of the liver. These fat areas can evolve in a very short time and provoke in the case of focal incidence diagnostic problems of differentiation against abscesses or metastases. Due to this fact and because of the rapid reversibility of the fatty infiltration under therapy, the safest method to clarify the situation consists of short-term CT controls.     

Loss of echogenic lesion of focal fatty infiltration in fibrotic liver

Five alcoholics with chronic liver disease showed focal low density areas of the liver that varied in distribution on computed tomography (CT) but no corresponding lesions on ultrasonography. The densities of these areas on CT were much lower than that of spleen. All the areas disappeared 2 days to 4 weeks after patients entered the hospital, suggesting that they were focal areas of fatty liver. Four patients had liver cirrhosis and one liver fibrosis. These observations may add further evidence to our previous finding that increased echogenecity of the liver produced by fatty infiltration is attenuated by complicating fibrosis.     

脂肪肝内正常肝岛及正常肝内局灶脂肪变性的CT与MR诊断

目的：探讨脂肪肝内正常肝岛及正常肝内局灶脂肪变性的ＣＴ与ＭＲ征象。方法：６例脂肪肝内正常肝组织岛（Ａ组）与７例正常肝内局灶性脂肪变性（Ｂ组）病人,ＣＴ与常规ＳＥＴ１ 及Ｔ２ 加权及梯度回波Ｔ１ 加权ｉｎ－ ｐｈａｓｅ及ｏｕｔ－ ｐｈａｓｅ ＭＲ成像。结果：增强前、后ＣＴ显示正常肝组织岛保持正常肝组织与脾脏密度关系;肝组织局灶脂肪变性呈相对低密度。ＭＲＩＳＥＴ１、Ｔ２ 加权成像及梯度回波ｉｎ－ ｐｈａｓｅＴ１ 加权成像显示正常肝组织岛相对低信号区;局灶脂肪变性区呈稍高信号。梯度回波ｏｕｔ－ ｐｈａｓｅ Ｔ１ 加权成像正常肝组织岛呈高信号;局灶脂肪变性区呈低信号。脂肪抑制Ｔ２ 加权成像均呈等信号。结论：采用ＭＲ的梯度回波ｏｕｔ－ ｐｈａｓｅＴ１ 加权及ＴＳＥＴ２ 加权脂肪抑制成像可以诊断正常肝岛及正常肝内的局灶脂肪变性。     

Focal fatty infiltration of the liver: analysis of prevalence and CT findings in children and young adults

OBJECTIVE: Focal fatty infiltration of the liver, a benign entity that can be confused with a malignant lesion, is well characterized in adults but not in children. The goal of this study was to determine by CT the prevalence and characteristics of focal fatty infiltration in children and young adults. MATERIALS AND METHODS: We retrospectively analyzed 305 consecutive contrast-enhanced abdominal CT examinations of 218 children and young adults with no known liver disease, performed during 2 years at our institution, to identify focal fatty infiltration of the liver. The imaging criterion for focal fatty infiltration of the liver on helical CT was a geometric or ovoid low-attenuation area adjacent to the falciform ligament, gallbladder fossa, or porta hepatis. If a patient's findings met the CT criterion for focal fatty infiltration of the liver, all previous abdominal CT and MR imaging examinations performed for that patient were reviewed to assess the evolution of focal fatty infiltration of the liver. RESULTS: Of 218 children and young adults, 20 (9.2%) met the CT criterion for focal fatty infiltration of the liver. In our population, focal fatty infiltration of the liver was identified only adjacent to the falciform ligament. The prevalence of focal fatty infiltration of the liver increased significantly with advancing age: 0% for ages 1 month-4 years; 7.3% for 5-9 years; 10.2% for 10-14 years, and 25.6% for 15-19 years (p < 0.0001). CONCLUSION: Focal fatty infiltration of the liver was identified in 9.2% of patients in our population, and occurrence of this lesion in children increases significantly with advancing age. However, focal fatty infiltration of the liver is uncommon in infants and young children and should be a diagnosis of exclusion.     

Focal sparing in fatty infiltration of the liver

Four cases of focal sparing in otherwise diffuse fatty infiltration of the liver are reported. The characteristic features are described as shown at sonography, computed tomography (CT) and scintigraphy. It is emphasised that, with ultrasound, if the increased echogenicity of the majority of the liver is not appreciated, then the area of normal hepatic parenchyma may be misinterpreted as a pathological hypoechoic lesion.     

Large focal defect on liver/spleen scan caused by fatty liver and masquerading as neoplasm.

Focal fatty infiltration of the liver may be mistaken for metastatic disease, primary tumor or other space-occupying lesions on CT or ultrasound. Usually, a 99mTc-sulfur colloid scan is sensitive in documenting the presence of Kupffer's cell in such a process. We present a case that was suggestive of focal fatty infiltrate on a CT scan, nondiagnostic on ultrasound, and seen as a large focal defect on the 99mTc-sulfur colloid liver/spleen scan. A 133Xe inhalation study, however, did show uptake in the area of fatty infiltration. A needle biopsy confirmed the diagnosis.     

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.     

MR spectroscopy in the diagnosis of cerebral amyloid angiopathy presenting as a brain tumor

We present two cases of focal, tumefactive, masslike lesions of diffuse cerebral amyloid angiopathy (CAA) that presented as areas of increased signal intensity on long TR sequences without contrast enhancement or restricted diffusion. MR spectroscopy revealed normal metabolite ratios and unremarkable spectra. Pathologic tissue showed CAA and CAA with angitis of the CNS. Tumefactive CAA is a rare condition, and we describe its characteristics at MR spectroscopy and diffusion-weighted imaging.     

CT arteriographic confirmation of focal hepatic fatty infiltration adjacent to the falciform ligament associated with drainage of inferior vein of Sappey: a case report

We experienced a case of focal fatty infiltration in the anteromedial edge of the medial segment of the liver adjacent to the falciform ligament associated with advanced esophageal cancer. By using CT during selective right internal thoracic arteriography, we confirmed that the inferior vein of Sappey drained into the area of focal fatty infiltration. This is the first case to directly establish the relationship between drainage of the inferior vein of Sappey and occurrence of focal fatty infiltration of the liver.     

Focal sparing of segment 2 in fatty liver: US appearance

PURPOSE: To determine the frequency and sonographic features of focal sparing of fatty liver at segment 2. MATERIALS AND METHODS: The sonographic database was searched over the preceding three years. The criteria for sonographic diagnosis of focal sparing of fatty liver was an area of liver parenchyma of relatively low echogenicity with lack of mass effect. RESULTS: Six (0.9%) of 686 patients with diffuse fatty liver showed focal sparing at segment 2. The areas showed spherical or ovoid hypoechoic mass-like lesions measuring 2 to 6 cm in longest diameter (average, 3.8 cm). These all abutted on the posterior surface of segment 2 adjacent to the ligamentum venosum. These were segmental in two cases and subsegmental in four. CONCLUSION: In diffuse fatty liver, segment 2 is infrequently spared, and this may be a helpful adjunct sign of fatty liver.     

Focal manifestations of diffuse liver disease at MR imaging.

Detection and exclusion of focal liver lesions is especially difficult in patients with diffuse liver disease. Magnetic resonance (MR) imaging may be particularly valuable in these patients. By judicious comparison of appropriate pulse sequences, normal and hypertrophic liver may be distinguished from atrophic, neoplastic, or otherwise abnormal hepatic parenchyma. Chemical shift (lipid-sensitive) techniques allow definitive identification of fatty liver, including focal fatty infiltration or focal sparing. T2-weighted and T2*-weighted images allow identification of iron overload, depicting malignancies as focal masses without iron. Analysis of signal intensity and internal morphology allows confident distinction between regenerative nodules and hepatocellular carcinoma in most instances, and allows diagnosis of early carcinoma within regenerative nodules. MR imaging provides capabilities for noninvasive characterization of liver tissue beyond those available with other noninvasive modalities.     

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.     

Radiocolloid liver imaging in hepatic steatosis

In a review of 60 patients with fatty infiltration of the liver documented by Xe-133 imaging, 43% had normal radiocolloid liver images, and 57% had abnormal images with various combinations of hepatomegaly, mottling, splenomegaly, and splenic shift of radioactivity. None, however, showed focal defects. Fatty infiltrates do not simulate mass lesions on the radiocolloid study of the liver, and an area of photon deficiency in the presence of hepatic steatosis points to an additional pathologic process. The interpretation of the radiocolloid liver image is unhindered by fatty infiltration when searching for discrete space-occupying lesions.     

Role of MRI for the diagnosis and prognosis of multiple myeloma

For the correct staging of patients with multiple myeloma sensitive detection is mandatory in order to estimate prognosis and to decide for adequate therapy. Magnetic resonance imaging (MRI) is superior to radiography for both, focal and diffuse involvement. Five different infiltration patterns can be differentiated: (1) normal appearance of bone marrow despite minor microscopic plasma cell infiltration, (2) focal involvement, (3) homogeneous diffuse infiltration, (4) combined diffuse and focal infiltration, (5) "salt-and-pepper"-pattern with inhomogeneous bone marrow with interposition of fat islands. For the fast and complete assessment of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique should be employed. The focal involvement is clearly demonstrated as areas of high signal intensity on, e.g. STIR images. Diffuse involvement is best detected on unenhanced T1-weighted SE sequences and it manifests as homogeneous signal reduction. It can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. With parallel imaging and special coil devices, such as total imaging matrix (Siemens systems, Avanto) a "screening" of the whole red bone marrow as for myeloma infiltration is possible within a reasonable time. Patients without bone marrow infiltration have a significantly longer survival than patients with bone marrow infiltration in MRI at the time of diagnosis. However, even in stage I disease (Durie and Salmon) and negative X-ray films bone marrow infiltration in MRI may be detected in 29-50% of patients. Those patients typically show an earlier disease progression. Recently, MRI has been implemented in the clinical staging of patients with multiple myeloma. MRI may also monitor response to therapy. Signs of good response in cases with focal involvement are: reduction of signal intensity on T2-weighted spin echo images, lack or rim-like enhancement after contrast material injection or even a normalisation of bone marrow signal. In case of diffuse involvement a partly patchy reconversion to fatty marrow can be seen.     

Pseudotumor of the quadrate lobe in hepatic sonography: a sign of generalized fatty infiltration

Sonograms of 43 patients demonstrated a focal area of decreased echogenicity in the medial segment of the left hepatic lobe (quadrate lobe). The shape ranged from ovoid to sheetlike, and the diameter ranged from 0.7 to 8.6 cm. The echogenicity of the right hepatic lobe was abnormally increased in 34 of 37 scans graded. In 20 patients with follow-up sonograms, 11 showed no change, six disappeared and three decreased in size. In 12 patients with unenhanced CT scans, 10 had decreased attenuation of the hepatic parenchyma and normal attenuation in the observed quadrate lobe focus. The hypoechoic focus in the quadrate lobe represents focal sparing in generalized fatty infiltration of the liver. When present, this focus represents a useful qualitative sign of generalized fatty infiltration in the rest of the liver.     

Pseudomass of the bladder neck after prostatectomy: report of two cases

The authors reviewed ultrasonographic (US) images, cystoscopic findings, and biopsy results at the vesicourethral anastomosis in two patients suspected of having local recurrence after radical prostatectomy. A focal, masslike bulge was identified with US at the posterior aspect of the bladder neck, just above the anastomosis. This bulge mimicked the appearance of local recurrence of cancer; however, diagnostic studies, biopsy results, and clinical follow-up failed to demonstrate recurrent cancer. A review of the surgical technique led the authors to conclude that a pseudomass at the vesicourethral anastomosis may result from focal infolding of normal bladder mucosa.     

Diagnostik des Plasmozytoms mit der MRT

Background. In multiple myeloma 5 different infiltration patterns can be differentiated: 1. normal appearance of bone marrow, 2. focal involvement, 3. homogeneous diffuse infiltration, 4. combined diffuse and focal infiltration, 5. “salt- and pepper” pattern with inhomogeneous bone marrow with interposition of fat islands. Methods. For the fast and total acquisition of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique is superior. The focal involvement is clearly demonstrated as areas of high signal intensity on e. g. STIR images. Diffuse involvement can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. MRI is superior to X-ray in focal and diffuse involvement. With ultrafast sequences a “screening” of the whole red bone marrow as for myeloma infiltration is possible. Prognosis. In prognosis studies diffuse infiltration is inferior to focal involvement. Patients without bone marrow infiltration have a significantly longer survival than patients with bone marrow infiltration in MRI at the time of diagnosis. However, even patients in stage one of disease (Durie and Salmon) and negative X-ray films can show bone marrow infiltration in MRI. Those patients often show an early disease progression. Good response to therapy in focal involvement are: reduction of signal intensity on T2- weighted spin echo images, lack or rim- like enhancement after contrast material injection or even a normalisation of bone marrow signal. In case of diffuse involvement a partly patchy reconversion to fatty marrow can be seen.     

Value of MR imaging in evaluating focal fatty infiltration of the liver: preliminary study.

Focal fatty infiltration of the liver is a well-known entity that occasionally mimics metastatic disease on ultrasonographic (US) and computed tomographic (CT) scans and requires biopsy for diagnosis. To determine if high-field-strength magnetic resonance (MR) imaging might be useful in the differential diagnosis of the lesions, the authors compared US, CT, and MR findings in three patients with biopsy-proved fatty hepatic lesions. Areas of focal fatty infiltration were hyperechoic on US scans and had low attenuation on CT scans. No mass effect of the lesions on vascular structures or liver contours was observed, particularly on contrast material-enhanced CT scans. For all three patients, MR findings suggested the correct diagnosis by demonstrating focal high signal intensity on spin-echo T1- and T2-weighted images. On the basis of these preliminary findings, it appears that focal fatty infiltration of the liver may be differentiated from metastatic disease by means of high-field-strength MR imaging.