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.     

Nuclear medicine evaluation of focal fatty infiltration of the liver

Focal fatty infiltration of the liver (FFIL) occasionally may be mistaken as metastatic disease, primary liver malignancy, or other space-occupying lesions on CT or ultrasound studies, especially if there is significant mass effect. In these confusing cases, Xe-133 liver imaging has been advocated for confirmation of FFIL, since such studies have been reported to be sensitive and specific. The authors present results of four Xe-133 and four Tc-99m sulfur colloid scans in six patients with FFIL. Xe-133 imaging was found useful for diagnostic confirmation in only one patient and was misleading in the other three. Routine liver-spleen imaging was a more reliable method of confirmation, since no focal defects were found in any of the patients.     

Focal liver lesions in multiple myeloma: ecography, computed tomography, and magnetic resonance findings. A case report

According to autopsy data, diffuse hepatic infiltration occurs in up to 50% of cases with multiple myeloma. However, focal infiltration (single or multiple), although exceptional, is also possible. Therefore, multiple myeloma should be included in the extensive differential diagnosis of space-occupying liver lesions. We present the case of a 71-year-old man diagnosed with multiple myeloma with multiple focal lesions in the liver and spleen studied by different imaging techniques (ultrasound, multi-phase computed tomography and magnetic resonance). The definitive diagnosis was made by immunohistochemical analysis of material obtained by US-guided fine needle aspiration. We review the imaging findings reported in the literature for focal liver lesions in multiple myeloma and in extramedullary plasmacytoma of the liver.     

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.     

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.     

Solitary defect on liver sulfur colloid imaging secondary to focal fatty infiltration

Radionuclide liver-spleen imaging using Tc-99m SC may identify focal defects on routine examinations. Fatty infiltration has generally been described as a diffuse process in the liver that may be manifested on Tc-99m SC liver imaging as a nonhomogeneous pattern of radiopharmaceutical distribution or multiple small defects. This case demonstrates a focal defect on radionuclide imaging, simulating a space-occupying lesion that ultimately proved to be focal fatty infiltration. Although not an uncommon finding on CT, to the authors' knowledge this has not been reported in the nuclear medicine literature to date.     

99mTc red blood cell scintigraphy in evaluating focal liver lesions

To determine the accuracy of blood-pool imaging in the diagnosis of hepatic hemangiomas, 39 patients with various focal hepatic lesions were studied. The diagnoses in these patients were made by biopsy, angiography, surgical exploration, or clinical stability for a minimum of 14 months. The diagnoses were: hemangiomas (13 patients), hepatoma (three), metastases (19), abscesses (two), and liver cysts (two). After modified in vivo labeling of red blood cells with 20 mCi (740 MBq) of 99mTc pertechnetate, an initial flow study and early (1-15 min) and delayed (1-2 hr) static images were obtained. Increased blood-pool activity with a discordant flow pattern was seen in 11 of 13 patients with hemangiomas. False-negative scans occurred in two hemangiomas with extensive fibrosis. Two of three hepatomas had increased blood-pool activity associated with increased flow in a pattern identical to the increased blood-pool activity. None of the metastatic, abscess, or cystic lesions had increased blood-pool activity at any time after injection. It is concluded that 99mTc red blood cell imaging can distinguish hemangiomas from other focal liver lesions.     

Scintigraphic and ultrasound features of giant hemangiomas of the liver

Giant hemangiomas of the liver are clinically distinct from smaller and more innocent hemangiomas as they are more prone to complications. On imaging with ultrasound, they can also be readily confused with hepatoma, metastatic disease, or focal nodular hyperplasia. Nine giant hemangiomas (maximal diameter greater than 8 cm) were studied by scintigraphy and ultrasound. In all instances, the fill-in of the lesion on [99mTc]RBC scintigraphy indicated the diagnosis of hemangioma, adding specificity to the screening sonographic study. The pattern of fill-in on scintigraphy also appeared to be size dependent with lesions less than 11 cm in diameter equilibrating uniformly, while larger abnormalities intensified in centripetal fashion.     

Characteristic sonographic signs of hepatic fatty infiltration

Hepatic fatty infiltration sonographically appears as an area of increased echogenicity. When focal areas of fat are present in otherwise normal liver parenchyma, the fatty area may be masslike in appearance, leading to further imaging evaluation and sometimes even biopsy. This article discusses seven patients with focal fatty infiltration, who had sonographic signs that were highly suggestive of the fatty nature of the masses. These signs included angulated, geometric margins between normal and fatty tissue and interdigitating margins with slender fingers of normal or fatty tissue. These signs may be useful in diagnosing masslike areas of focal fatty infiltration and distinguishing these sonographically from other hepatic mass lesions.     

Positron tomographic imaging of the liver: 68 Ga iron hydroxide colloid

A new radiopharmaceutical, 68Ga ion hydroxide colloid, for hepatic imaging by positron emission tomography was prepared from the eluate of a 68Ge-68Ga solvent extraction generator. In rats, 84% of the administered dose of colloid localized in the liver and 4.6% accumulated in the spleen. Initial imaging studies in normal dogs showed close correspondence of the findings by positron tomography and transmission computed tomography. Emission tomography with 68Ga-colloid was performed in 10 patients with hepatic metastases demonstrated by conventional 99mTc sulfur colloid scintigraphy. All focal defects noted on the conventional scintigrams were easily identified and generally were seen more clearly by positron tomography. In one patient, additional lesions not identified on the initial 99mTc sulfur colloid images were demonstrated. The positron tomographic images were compared with those obtained by transmission computed tomography in seven patients; the two studies showed comparable findings in five patients, whereas positron tomography more clearly showed multiple lesions in two. Our results suggest that positron emission tomography is a suitable technique for obtaining high contrast, cross-sectional images of large abdominal organs.     

Simultaneous 99mTc double labelling of the hepatic reticuloendothelial system and of the red blood cells: a simplified method for the detection of liver hemangiomas

Sonographic images of liver hemangioma are not specific. Causal detection imposes further investigations (angiography, CT, NMR) which are not always practicable. 99mTc-red blood cells study after 99mTc colloid liver scintigraphy has been already proposed. Ten patients with hepatic hemangiomas were evaluated by simplified, simultaneous in vivo double labelling of the reticuloendothelial system and red blood cells by means of successive i.v. injections of SnCl2, 99mTc colloid albumin and 99mTc-pertechnetate. Focal colloid defects filled with the labelled RBC were revealed in 9/10 liver hemangiomas. Angioscintigraphy showed decreased perfusion and RBC scintigraphy an increased blood volume in the focal colloid defects due to the hemangiomas.     

Xenon-133 hepatic retention ratio: a useful index for fatty liver quantification

Xenon-133 hepatic retention ratio was developed for quantifying fatty liver. Data were acquired in frame mode in the hepatic region and both lung bases for 5 min after rebreathing 20 mCi of gaseous 133Xe and for another 5 min during washout. Static [99mTc]sulfur colloid liver imaging was performed with the patient in the identical position immediately after the ventilation study and data were stored for liver localization. A hepatic time-activity curve corrected for background activity was generated. The 133Xe retention ratio was derived by dividing the activity at 3.5 min after washout by the peak activity. The data of 16 controls and 20 patients with fatty liver were analyzed. The retention ratio (mean +/- s.d.) was greatly increased in patients with fatty infiltration (0.43 +/- 0.20 vs. 0.04 +/- 0.08 in controls, p less than 0.001). There was a strong positive correlation between the 133Xe retention ratios and percentage of fat on biopsy as assessed by the amount of the liver tissue occupied by fat globules on H & E stained sections. The 133Xe hepatic retention ratio is a simple, accurate and clinically useful index of detecting, quantifying and managing fatty infiltration of the liver.     

CT and MR appearance of focal nodular hyperplasia of the liver in children with biliary atresia

Two children with biliary atresia are described in whom focal nodular hyperplasia of the liver occurred following portoenterostomy. The lesions were low-or iso-dense on unenhanced CT and became hypodense post-contrast enhancement. There was normal 99mTc phytate on hepatic colloid scintigraphy. On T2-weighted spin echo MR images, there was increased signal intensity within the masses, and the surrounding liver parenchyma was divided by linear septa in one of the two cases.     

Triple radioisotope technique in etiologic evaluation of space-occupying lesions of the liver.

The findings from 43 patients with histologically proven focal liver disease examined by triple isotope tracer study are presented. The method consisted in a three step technique, the first step being an isotope scan after injection of 99mTc-sulfur colloid and 131I rose bengal. As a second step dynamic hepatic scintiangiography was carried out with 99mTc human serum albumin in order to assess the vascularity of a lesion detected on the initial scan. Thirdly, the patient was administered 67Ga to evaluate further the pathologic process. According to our results this triple radioisotope technique provides the clinician with valuable information on the possible etiology of focal liver disease.     

Atypical appearance of an hepatic hemangioma with technetium-99m red blood cell scintigraphy

Three-phase 99mTc red blood cell scintigraphy is an established technique for distinguishing hemangiomas from other focal liver lesions. The most widely recognized feature is the perfusion to blood-pool "mismatch" characterized by decreased or normal arterial perfusion, with lesion activity which progressively increases over 1-2 hr. Although increased arterial vascularity of hemangiomas has been described, such cases either involved small portions of the lesion only or occurred in lesions not conclusively proven to be hemangiomas. We report a case of an angiography proven hemangioma with increased arterial vascularity involving a significant portion of the lesion as well as intense early blood-pool activity similar to that seen on delayed imaging. This case emphasizes the diverse appearance of hepatic hemangiomas using 99mTc blood cell scintigraphy.     

脂肪肝：MRI影像表现及MRI序列选择

目的：选择评估脂肪肝的MRI序列和认识脂肪肝的MRI影像表现以帮助鉴别诊断,方法：18例脂肪肝病人进行了肝脏平扫和增强MRI,采用屏气同,反相位T1加权梯度回波序列,2D FLASH加脂肪抑制T1WI以及HASTE T2WI。结论：18例肝脂肪变中伴有7例肝癌,2例血管瘤,1例囊肿,5例肝硬化;弥漫型脂肪浸润6例,局灶型脂肪浸润12例,脂肪肝影像表现,T1WI同相位表现为稍高或等信号,反相位或加压脂T1WI呈低信号;T2WI呈稍高或等信号,部分脂肪肝伴脂内肿块在反相位或加压脂TWI上可见低信号肿块周边全周或部分环状高信号带,在增强MRI上无明显强化,有时见少量小血管进入其内,结论：同与反相位MRI能较好鉴别诊断脂肪肝,两者互补,缺一不可,可避免脂肪肝的误诊或汤诊。建议对疑有脂肪肝患者行同,反相位T1加权MRI扫描。     

Comparison of 99mTc and 123I for thyroid imaging.

Thyroid images were obtained with 99mTc and 123I, using a scintillation camera and pinhole collimator, from 85 patients selected from over 1,000 patients predisposed to the development of thyroid neoplasms by prior radiotherapy. In 66 of 85 patients 99mTc and 123I gave essentially similar information, whereas in 19 patients some thyroid-image disparity was seen. In 11 of these 19, focal areas of increased 99mTc concentration were not seen with 123I. Radioiodide images showed slightly better contrast than the 99mTc images but required a longer imaging time and usually did not provide more information; in a few cases 99mTc showed abnormalities more readily. Regardless of which radionuclide was used, oblique views were needed to define some abnormalities. Currently 123I does not provide significant advantages over 99mTc for routine thyroid imaging. However, 123I is preferred in patients with very poor thyroid function and in those with suspected retrosternal thyroid tissue. In addition, areas of increased 99mTc concentration should also be studied with 123I.     

Computed tomographic and ultrasound appearances of focal spared areas in fatty infiltration of the liver

Computed tomography (CT) and ultrasound (US) appearances of diffuse and focal fatty infiltration of the liver (FIL) are well recognized. We have recently seen 10 cases with "fat spared" areas in FIL presenting as pseudo tumours of the liver. Characteristic appearances of fat free areas in FIL which help differentiate these areas from other focal liver lesions include (i) location in the medial segment of the left lobe of the liver, (ii) absence of mass effect on surrounding vessels and liver tissue, and (iii) presence of typical changes of FIL elsewhere in the liver on CT or US examination.     

Ultrasonography of alcoholic liver disease with histological correlation

In alcoholic liver disease (fatty infiltration, alcoholic cirrhosis), the liver is diffusely abnormal on ultrasound. Changes in size, dilatation of the hepatic veins, and ascites may also occur. The authors conducted a histological correlation of these abnormalities in 22 alcoholic patients and 16 controls, grading the changes on a scale of 0 to 4+ for fat, fibrosis, and necrosis and noting tumor whenever present. Ultrasound detected abnormality in 21 cases (sensitivity = 95%) and correctly identified 15 controls (specificity = 94%). Of the 5 tumors seen, 4 hepatomas were detected and biopsied and 1 metastatic squamous-cell carcinoma was missed. Applications of commercially available A-scan module are considered and its limitations discussed. With the exception of minimal change (1+ fat or fibrosis), ultrasound detected many of the pathological changes seen in alcoholic liver disease.     

Usefulness of 111In labeled leukocytes scintigraphy combined with 99mTc phytate liver scintigraphy for diagnosis of hepatic abscess comparing with CT and US]

111In labelled leukocyte scintigraphy (ILLS) was performed in five patients with hepatic abscess. For the accurate diagnosis of hepatic abscess, ILLS was superimposed on 99mTc phytate liver scintigraphy. The results of ILLS were compared with CT and US findings. Four of five patients (80%) showed abnormal accumulations in the liver. The smallest abscess detected was 46 mm x 43 mm. CT scan showed rim enhancement, which was a specific finding for hepatic abscess, in three patients. It was rather difficult to diagnose hepatic abscess by US. In two cases without definite rim enhancement on CT, the abscesses were diagnosed as hot spots by ILLS. We conclude that ILLS combined with 99mTc liver scintigraphy is useful for the diagnosis of hepatic abscess.