Multiple Liver Amoebic Abscesses Detected on FDG PET/CT

Elevated 68 Ga-FAPI Activity in Klebsiella pneumoniae Invasion Syndrome

ABSTRACT

Klebsiella pneumoniae invasion syndrome is a rare disease associated with primary liver abscess and secondary extrahepatic infection. We report a case of K. pneumoniae invasion syndrome with elevated 68 Ga-FAPI uptake, mimicking malignancy with multiple metastases. Our case illustrated that K. pneumoniae invasion syndrome should be considered as a possible etiology when diagnosing multiple 68 Ga-FAPI-avid liver foci with metastatic lesions. Besides, PET/CT could be an integrated tool to search for systemic occult lesions in K. pneumoniae invasion syndrome.

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.

Acute Findings on FDG PET/CT: Key Imaging Features and How to Differentiate Them from Malignancy

PURPOSE OF REVIEW

To review acute findings commonly encountered during routine clinical FDG PET/CT studies and present key imaging features to differentiate them from malignant counterparts.

RECENT FINDINGS

FDG PET/CT is extensively used in routine clinical practice for oncology patients. Incidental acute findings in patients undergoing FDG PET/CT are increasingly common, and awareness of these findings and their mimics are important in delivering a clinically relevant and accurate radiological report for directing further management.

SUMMARY

This article will review examples of common acute findings encountered during routine FDG PET/CT scans, compare them against examples of FDG-avid malignancy that can mimic these findings and emphasize key imaging findings to differentiate acute findings from their malignant mimics.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

Liver Disease in Sri Lanka

Liver disease in Sri Lanka is mainly due to alcoholic liver disease and nonalcoholic fatty liver disease. In contrast to other South Asian countries, the prevalence of hepatitis B and C is low in Sri Lanka and prevalence of hepatitis A is intermediate. The few reported cases of hepatitis E in Sri Lanka are mainly in people who have traveled to neighboring South Asian countries. Wilson's disease, autoimmune hepatitis, hemochromatosis, drug-induced liver disease, and primary biliary cirrhosis are recognized causes of liver disease in Sri Lanka. Pyogenic and amebic liver abscesses and dengue infection are the other causes of liver disease. Some of the commonly used plants as traditional herbal medicine in Sri Lanka have been shown to have deleterious effects on the liver in animal studies. Considering the high popularity of traditional herbal medicine in the country, it is likely that herbal medicine is an etiological factor for liver disease in Sri Lanka, but no published data are available. Address reprint requests to: Wijewantha HS. Liver Disease in Sri Lanka. Euroasian J Hepato-Gastroenterol 2017;7(1):78-81.

Focally Increased FDG Activity in the Liver Related to Hydropic Degeneration

A 50-year-old man, who had diffuse large B-cell lymphoma in the neck and just finished 4 cycles of chemotherapy, presented to our department to evaluate the status of the disease. FDG PET/CT revealed a focally increased activity in the right lobe of the liver. However, pathological examination showed hepatocyte hydropic degeneration with associated inflammatory cells without evidence of malignancy.

FDG PET/CT Findings in Multiple Splenic Amebomas (Amebic Granulomas)

Splenic ameboma (amebic granuloma) is rare. A 38-year-old man with a severe pneumonia due to inhalation of swimming pool water 18 months ago complained of night sweat, tiredness, and anorexia for 1 month. Abdominal ultrasound showed multiple nodules in the spleen. These nodules showed slight enhancement on enhanced CT and intense FDG uptake on PET/CT. Splenectomy was performed. Multiple splenic amebomas were confirmed by pathology. Free-living amoebae were also detected in samples of pleural effusion and blood. Splenic ameboma, although rare, should be included in the differential diagnosis with isolated focally increased FDG activity in the spleen.

Diffuse Hepatic FDG Activity From Nonmalignant Etiologies

Diffuse increased ¹⁸F-FDG activity is commonly caused by malignant involvement. We describe here cases of diffuse, uniformly increased ¹⁸F-FDG activity due to nonmalignant illnesses in 2 patients: one had parvovirus B19 infection, whereas the other had porphyria, a heme synthesis disorder.