F-18 FDG uptake in focal fatty infiltration of liver mimicking hepatic malignancy on PET/CT images

Rim 18F-fluorodeoxyglucose uptake of hepatic cavernous hemangioma on positron emission tomography/computed tomography: A case report

BACKGROUND

Peripheral FDG accumulation in a hepatic hemangioma presenting in a patient with prolonged fever is rare. Therefore, clinicians should pay close attention to patients with hepatic mass.

CASE SUMMARY

A 54-year-old woman with a 4-wk history of daily fevers was admitted to our hospital. A whole body 18F-Fluordesoxyglucose (PET-FDG) positron emission tomography/computed tomography (PET/CT) was performed to elucidate the source of the fever. However, whole body 18F-FDG PET/CT raised the suspicion of a malignant lesion because of peripheral FDG accumulation (SUVmax 3.5 g/mL) higher than that of the normal liver parenchyma (SUVmax 1.6 g/mL) surrounding a hypoactive area, and no other abnormalities were showed. Subsequently, the patient underwent liver mass resection. Histopathology showed a hepatic cavernous hemangioma with fatty infiltration around the lesion. The fever disappeared four days after surgery and the patient did not present any complications during follow-up.

CONCLUSION

Fatty infiltration in the peripheral parts of hepatic cavernous hemangioma may lead to subacute inflammation which further activate the Kupffer cells. This may cause prolonged fever and peripheral rim FDG accumulation on PET/CT.

The effect of hepatic steatosis on 18F-FDG uptake in PET-CT examinations of cancer Egyptian patients

BACKGROUND

Hepatic steatosis is the most common chronic hepatic disease. Imaging diagnosis of hepatic steatosis has been evaluated as an alternative to invasive histological diagnosis.

STUDY AIMS

The study aimed to assess the effect of hepatic steatosis on Flourine-18 fluorodeoxyglucose (18F-FDG) uptakes in cancer patients.

PATIENTS AND METHODS

Blood samples were collected from 50 cancer patients and analyzed to calculate fatty liver index and Hepatic steatosis index (HIS). Hepatic steatosis examined using high-resolution ultrasound and positron emission tomography-computed tomography (PET-CT). Linear attenuation coefficient, standardized-uptake value (SUV) mean (SUV mean), and SUV maximum (SUVmax) were measured. Accordingly, patients were divided equally into non-fatty liver, and fatty liver groups.

RESULTS

A significant increase in SUVmax and SUV mean was observed in the fatty liver group more than in the non-fatty liver group. HSI significantly increased in the fatty liver group compared to the non-fatty liver group. Liver tissue uptake FDG was significantly correlated with HSI values. SUV max significantly correlated with body mass index (BMI) in the non-fatty group only.

CONCLUSION

Hepatic changes in cancer patients affect the liver metabolic activity and thus the 18 F-FDG uptake. Therefore, further corrections should be considered when the liver is used as a comparator for PET-CT scans of cancer patients.

Subtly Increased Focal FDG Activity in the Liver Due to Paragonimiasis

ABSTRACT

A 32-year-old man underwent 18 F-FDG PET/CT to evaluate suspicious hepatic metastases, which were revealed by ultrasonography and MRI. The FDG PET/CT images demonstrated only one focus of subtly increased activity in the liver without abnormality elsewhere. The pathological result from hepatic biopsy was consistent with Paragonimus westermani infection.

PET/CT Variants and Pitfalls in Liver, Biliary Tract, Gallbladder and Pancreas

A wide variety of pathological anomalies may occur in the liver, biliary system, and pancreas. It is a necessity to use many different imaging techniques in order to distinguish such varied pathologies, especially those from malignant processes. Positron Emission Tomography/Computed Tomography (PET/CT) is an imaging method that has proven its diagnostic value in oncology and can be used for different clinical purposes. Fluoro-18 fluoro-2-deoxy-D-glucose has a wide range of uses as a dominant radiopharmaceutical in routine molecular imaging, however, molecular imaging has started to play a more important role in personalized cancer treatment in recent years with new Fluoro-18 and Gallium-68 labeled tracers. Although molecular imaging has a strong diagnostic effect, the surprises and pitfalls of molecular imaging can lead us to unexpected and misleading results. Prior to PET/CT analysis and reporting, information about possible technical and physiological pitfalls, normal histological features of tissues, inflammatory pathologies, specific clinical features of the case, treatment-related complications and past treatments should be evaluated in advance to avoid misinterpretation. In this review, the physiological and pathophysiological variants as well as pitfalls encountered in PET/CT imaging of the liver, biliary tract, gallbladder, and pancreas will be examined. Other benign and malignant pathologies that have been reported to date and that have led to incorrect evaluation will be listed. It is expected that the devices, software, and artificial intelligence applications that will be developed in the near future will enable much more effective and faster imaging that will reduce the potential causes of error. However, as a result of the dynamic and evolving structure of the information obtained by molecular imaging, the inclusion of the newly developed radiopharmaceuticals in routine practice will continue to carry new potentials as well as new troubles. Although molecular imaging will be the flagship of diagnostic oncology in the 21st century, the correct analysis and interpretation by the physician will continue to form the basis of achieving optimal performance.

Variations of the liver standardized uptake value in relation to background blood metabolism: An 2-[18F]Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography study in a large population from China

To investigate the influence of background blood metabolism on liver uptake of 2-[F]fluoro-2-deoxy-D-glucose (F-FDG) and search for an appropriate corrective method.Positron emission tomography/computed tomography (PET/CT) and common serological biochemical tests of 633 healthy people were collected retrospectively. The mean standardized uptake value (SUV) of the liver, liver artery, and portal vein (i.e., SUVL, SUVA, and SUVP) were measured. SUVL/A was calculated as SUVL/SUVA, while SUVL/P was calculated as SUVL/SUVP. SUV of liver parenchyma (SUVLP) was calculated as SUVL - .3 × (.75 × SUVP + .25 × SUVA). The coefficients of variation (CV) of SUVL, SUVL/A, SUVL/P, and SUVLP were compared to assess their interindividual variations. Univariate and multivariate analyses were performed to identify vulnerabilities of these SUV indexes to common factors assessed using serological liver functional tests.SUVLP was significantly larger than SUVL (2.19 ± .497 vs 1.88 ± .495, P < .001), while SUVL/P was significantly smaller than SUVL (1.72 ± .454 vs 1.88 ± .495, P < .001). The difference between SUVL/A and SUVL was not significant (1.83 ± .500 vs 1.88 ± .495, P = .130). The CV of SUVLP (22.7%) was significantly smaller than that of SUVL (22.7%:26.3%, P < .001), while the CVs of SUVL/A (27.2%) and SUVL/P (26.4%) were not different from that of SUVL (P = .429 and .929, respectively). Fewer variables independently influenced SUVLP than influenced SUVL, SUVL/A, and SUVL/P; Only aspartate aminotransferase, body mass index, and total cholesterol, all P-values <.05.The activity of background blood influences the variation of liver SUV. SUVLP might be an alternative corrective method to reduce this influence, as its interindividual variation and vulnerability to effects from common factors of serological liver functional tests are relatively lower than the commonly used SUVL.

Imaging patterns and focal lesions in fatty liver: a pictorial review

Non-alcoholic fatty liver disease is the most common cause of chronic liver disease and affects nearly one-third of US population. With the increasing trend of obesity in the population, associated fatty change in the liver will be a common feature observed in imaging studies. Fatty liver causes changes in liver parenchyma appearance on imaging modalities including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) and may affect the imaging characteristics of focal liver lesions (FLLs). The imaging characteristics of FLLs were classically described in a non-fatty liver. In addition, focal fatty change and focal fat sparing may also simulate FLLs. Knowledge of characteristic patterns of fatty change in the liver (diffuse, geographical, focal, subcapsular, and perivascular) and their impact on the detection and characterization of FLL is therefore important. In general, fatty change may improve detection of FLLs on MRI using fat suppression sequences, but may reduce sensitivity on a single-phase (portal venous) CT and conventional ultrasound. In patients with fatty liver, MRI is generally superior to ultrasound and CT for detection and characterization of FLL. In this pictorial essay, we describe the imaging patterns of fatty change in the liver and its effect on detection and characterization of FLLs on ultrasound, CT, MRI, and PET.

18-Fluoro-deoxyglucose uptake in inflammatory hepatic adenoma: A case report

Positron emission tomography computed tomography (PET-CT) using 18-Fluoro-deoxyglucose (¹⁸FDG) is an imaging modality that reflects cellular glucose metabolism. Most cancers show an uptake of ¹⁸FDG and benign tumors do not usually behave in such a way. The authors report herein the case of a 38-year-old female patient with a past medical history of cervical intraepithelial neoplasia and pheochromocytoma, in whom a liver lesion had been detected with PET-CT. The tumor was laparoscopically resected and the diagnosis of inflammatory hepatic adenoma was confirmed. This is the first description of an inflammatory hepatic adenoma with an ¹⁸FDG up-take.

The predictive ability of liver function indexes on 18F-FDG uptake in the liver

AIM

The liver is an important reference organ for positron emission tomography/ computed tomography (PET-CT) examination using 18F-fluorodeoxyglucose (18F-FDG). However, 18F-FDG uptake by the liver is affected by many factors. We therefore investigated the effect of hepatic function on 18F-FDG uptake in the liver.

METHODS

A retrospective analysis of data on the hepatic function and the mean liver standardized up-take value (SUV) of 18F-FDG uptake in the liver during PET-CT examination of 500 (381 males, 119 females, aged 27-71) physical examinees.

RESULTS

The mean liver SUV was 1.88 ± 0.20. The correlation coefficient and partial correlation coefficient for age, the levels of conjugated bilirubin, globulin, AST and the mean liver SUV were statistically significant (r' = 0.119, -0.197, -0.089 and 0.151, all p < 0.05). Multiple linear regression analysis showed that age and the levels of conjugated bilirubin, globulin and aspartate amino-transferase (AST) were independent factors that influenced changes in the mean liver SUV (β = 0.008, -0.025, -0.151 and 0.005, all p < 0.05). The globulin level had the biggest predictive ability (β' = -0.151, p < 0.05).

CONCLUSIONS

The uptake of 18F-FDG in the liver was influenced by some liver function indexes. The levels of conjugated bilirubin, globulin and AST were independent factors for predicting changes in the uptake of 18F-FDG in the liver. Liver function test results should be combined with an evaluation of the metabolic activity of the liver.

Fat-Containing Hypermetabolic Masses on FDG PET/CT: A Spectrum of Benign and Malignant Conditions

OBJECTIVE

This article focuses on identifying the imaging appearances of hypermetabolic fatty masses and masslike lesions on PET/CT and understanding the diagnostic challenges radiologists may face while interpreting findings of these lesions on PET/CT. This article provides an approach to aid in the diagnosis of these lesions and the appropriate management of patients.

CONCLUSION

Both malignant and benign fat-containing masses and masslike lesions can show hypermetabolic activity on PET/CT. Although the differential diagnosis is broad, clinical history, anatomic location, and knowledge of anatomic variants and imaging features can help radiologists avoid misinterpretation of benign fatty lesions as malignancy.

Magnetic Resonance Imaging of Liver Metastasis

Liver magnetic resonance imaging (MRI) is becoming the gold standard in liver metastasis detection and treatment response assessment. The most sensitive magnetic resonance sequences are diffusion-weighted images and hepatobiliary phase images after Gd-EOB-DTPA. Peripheral ring enhancement, diffusion restriction, and hypointensity on hepatobiliary phase images are hallmarks of liver metastases. In patients with normal ultrasonography, computed tomography (CT), and positron emission tomography (PET)-CT findings and high clinical suspicion of metastasis, MRI should be performed for diagnosis of unseen metastasis. In melanoma, colon cancer, and neuroendocrine tumor metastases, MRI allows confident diagnosis of treatment-related changes in liver and enables differential diagnosis from primary liver tumors. Focal nodular hyperplasia-like nodules in patients who received platinum-based chemotherapy, hypersteatosis, and focal fat can mimic metastasis. In cancer patients with fatty liver, MRI should be preferred to CT. Although the first-line imaging for metastases is CT, MRI can be used as a problem-solving method. MRI may be used as the first-line method in patients who would undergo curative surgery or metastatectomy. Current limitation of MRI is low sensitivity for metastasis smaller than 3mm. MRI fingerprinting, glucoCEST MRI, and PET-MRI may allow simpler and more sensitive diagnosis of liver metastasis.

PET-avid hepatocellular adenomas: incidental findings associated with HNF1-α mutated lesions

BACKGROUND

Hepatocellular adenoma (HCA) is the second most common benign liver neoplasm and occurs predominantly in women in their reproductive years. Positron emission tomography (PET) using [18F] fluorodeoxyglucose (FDG) is commonly used in cancer staging, surveillance and evaluation of treatment response. PET-avid HCA are rare and can be falsely interpreted as malignancies.

METHODS

A retrospective review of four institutions' database was performed to identify the PET-avid HCAs with clinico-pathological correlation.

RESULTS

Nine patients with histological proven PET-avid HCA was identified. Eight out of 9 patients were female with a median age at diagnosis of 44 years. All patients' tumors with available histological subtyping (8/8) were HNF1-α mutated and had no inflammatory changes; 6 out the 9 lesions had prominent (>50%) steatotic changes.

CONCLUSION

Hepatocellular adenomas, specifically the HNF1-α subtype, can cause false-positive PET findings when seeking to identify malignancy. Concomitantly, PET-CT may have the potential to identify the HCA histopathologic variant with the lowest malignant and hemorrhagic potential.

Impacts of biological and procedural factors on semiquantification uptake value of liver in fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging

BACKGROUND

Increased metabolic activity of fluorodeoxyglucose (FDG) in tissue is not only resulting of pathological uptake, but due to physiological uptake as well. This study aimed to determine the impacts of biological and procedural factors on FDG uptake of liver in whole body positron emission tomography/computed tomography (PET/CT) imaging.

METHODS

Whole body fluorine-18 ((18)F) FDG PET/CT scans of 51 oncology patients have been reviewed. Maximum standardized uptake value (SUVmax) of lesion-free liver was quantified in each patient. Pearson correlation was performed to determine the association between the factors of age, body mass index (BMI), blood glucose level, FDG dose and incubation period and liver SUVmax. Multivariate regression analysis was established to determine the significant factors that best predicted the liver SUVmax. Then the subjects were dichotomised into four BMI groups. Analysis of variance (ANOVA) was established for mean difference of SUVmax of liver between those BMI groups.

RESULTS

BMI and incubation period were significantly associated with liver SUVmax. These factors were accounted for 29.6% of the liver SUVmax variance. Statistically significant differences were observed in the mean SUVmax of liver among those BMI groups (P<0.05).

CONCLUSIONS

BMI and incubation period are significant factors affecting physiological FDG uptake of liver. It would be recommended to employ different cut-off value for physiological liver SUVmax as a reference standard for different BMI of patients in PET/CT interpretation and use a standard protocol for incubation period of patient to reduce variation in physiological FDG uptake of liver in PET/CT study.

PET-avid hepatocellular adenomas: incidental findings associated with HNF1-α mutated lesions

BACKGROUND

Hepatocellular adenoma (HCA) is the second most common benign liver neoplasm and occurs predominantly in women in their reproductive years. Positron-emission tomography (PET) using [18F] fluorodeoxyglucose (FDG) is commonly used in cancer staging, surveillance and evaluation of the treatment response. PET-avid HCA is rare and can be falsely interpreted as malignancies.

METHODS

A retrospective review of four institutions' database was performed to identify the PET-avid HCAs with clinico-pathological correlation.

RESULTS

Nine patients with histological proven PET-avid HCA was identified. Eight out of nine patients were female with a median age at diagnosis of 44 years. All patients' tumours with available histological subtyping (8/8) were HNF1-α mutated and had no inflammatory changes; six out the nine lesions had prominent (>50%) steatotic changes.

CONCLUSION

Hepatocellular adenomas, specifically the HNF1-α subtype, can cause false-positive PET findings when seeking to identify malignancy. Concomitantly, PET-CT may have the potential to identify the HCA histopathological variant with the lowest malignant and haemorrhagic potential.

The combined effects of serum lipids, BMI, and fatty liver on 18F-FDG uptake in the liver in a large population from China: an 18F-FDG-PET/CT study

OBJECTIVES

The aim of the study was to investigate the combined effects of serum lipids, BMI, and fatty liver on the liver uptake of fluorine-18 fluorodeoxyglucose ((18)F-FDG).

METHODS

A total of 676 individuals were retrospectively studied. The mean standardized uptake value (SUV) was used to quantify liver (18)F-FDG uptake. Univariate analyses and multivariate regression models identified variables that predicted the mean liver SUV before and after dichotomizing participants into low and high BMI groups.

RESULTS

The mean liver SUV (1.831 ± 0.417) differed significantly among nutritional categories (P = 0.005) and degrees of fatty liver (P < 0.001). An increase in mean liver SUV was noted in individuals with mild and moderate fatty liver compared with normal individuals and in overweight individuals compared with underweight individuals, whereas a downward trend was identified in both individuals with severe fatty liver and those who were obese. BMI had the strongest association with severity of fatty liver (r = 0.443, P < 0.001). Triglyceride, HDL, apolipoprotein-A, age, and BMI were independent variables predicting liver SUV mean in the whole population, whereas fatty liver severity presented as an independent variable only in the low BMI population (P = 0.031).

CONCLUSION

BMI, age, triglyceride, HDL, and apolipoprotein-A were independent variables predicting liver (18)F-FDG uptake. Mild and moderate degree of fatty liver had a positive effect on liver (18)F-FDG uptake, whereas a severe degree of fatty liver negatively affected (18)F-FDG uptake. Attention should be paid to liver metabolism in patients with fatty liver before using liver as the comparator in determining focal (18)F-FDG uptake elsewhere within the abdomen.

Hepatic adenoma mimicking a metastatic lesion on computed tomography-positron emission tomography scan

Positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is an imaging modality which reflects cellular glucose metabolism. Most malignant cells accumulate and trap ¹⁸F-FDG, allowing the visualisation of increased uptake. It is hence widely used to differentiate malignant from benign lesions. “False positive” findings of hepatic lesions have been described in certain instances such as hepatic abscesses, but are rare in cases involving hepatocellular adenomas. To our knowledge, there have been only 7 reports in the English literature documenting PET-avid hepatocellular adenomas; 6 of the 7 reports were published in the last 3 years with the first report by Patel et al. We report the case of a 44-year-old Chinese female patient with a history of cervical adenocarcinoma, referred for a hepatic lesion noted on a surveillance computed tomography (CT) scan. A subsequent CT-PET performed showed a hypermetabolic lesion (standardized uptake value 7.9) in segment IVb of the liver. After discussion at a multi-disciplinary hepato-pancreato-biliary conference, the consensus was that of a metastatic lesion from her previous cervical adenocarcinoma, and a resection of the hepatic lesion was performed. Histology revealed features consistent with a hepatocyte nuclear factor-1 α inactivated steatotic hepatocellular adenoma.

[Variations of the hepatic SUV in relation to the body mass index in whole body PET-CT studies]

OBJECTIVE

To evaluate SUV changes in the liver in relation to body mass index (BMI) of patients who undergo whole body PET-CT scans.

MATERIAL AND METHODS

A retrospective study was performed. The variables studied were injected dose of (18F)FDG (mCi), age (years), blood glucose level (mg/dL), height (cm) and weight (kg). BMI was calculated and the SUV mean value was expressed according to gender and BMI. A linear regression analysis was applied to identify the independent variables that best predict the SUV value.

RESULTS

Six hundred and three patients were studied (305 women, 298 men; mean age: 54.9±15.2 years old). Mean SUV measurement was significantly higher in males than females and increased significantly both in male and female patients who were overweight and even more in obese patients. The independent variables that best predicted the SUV value were gender, age, and BMI. In those patients having similar characteristics related to the analyzed variables, the SUV value increased by 0.002 for each increase in one year, and by 0.066 per unit increase in the BMI value.

CONCLUSIONS

Hepatic uptake of (18F)FDG increases according to the patient's BMI. The independent variables that best predict the hepatic SUV value are age and sex of patients. Our findings show that the practice of using the physiological hepatic metabolic activity level as a reference regarding questionable deposits elsewhere in the abdomen and pelvis is not useful, at least in male patients with overweightness and obesity.