Hepatocellular Carcinoma Mimicking Neuroendocrine Tumor Metastasis on 68Ga-DOTATATE PET/CT

Primary Hepatocellular Carcinoma Revealed on 68Ga-DOTATATE in a Patient With Nasopharyngeal Carcinoma

ABSTRACT

A 56-year-old man underwent a prospective study (ChiCTR2300070081), which is a head-to-head comparison of 18F-FDG and 68Ga-DOTATATE PET/MR in EB-positive nonkeratinizing nasopharyngeal carcinoma after chemotherapy. Bilateral cervical abnormal lymph nodes were both detected by 18F-FDG and 68Ga-DOTATATE PET/MRI, whereas 2 hepatic lesions only were shown on 68Ga-DOTATATE, which subsequent pathologically proved to be primary hepatocellular carcinoma.

18 F-MFBG PET/CT Is an Effective Alternative of 68 Ga-DOTATATE PET/CT in the Evaluation of Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

The current guidelines state that the functional imaging choice in the evaluation of metastatic pheochromocytoma and paraganglioma (PPGL) is 68 Ga-DOTATATE PET/CT. 18 F-meta-fluorobenzylguanidine ( 18 F-MFBG) is a new PET tracer and an analog of meta-iodobenzylguanidine (MIBG). This study aimed to compare 18 F-MFBG and 68 Ga-DOTATATE PET/CT in patients with metastatic PPGL.

PATIENTS AND METHODS

Twenty-eight patients with known metastatic PPGL were prospectively recruited for this study. All patients underwent both 18 F-MFBG and 68 Ga-DOTATATE PET/CT studies within 1 week. Lesion numbers detected were compared between these 2 studies.

RESULTS

18 F-MFBG PET/CT was positive for detecting metastases in all patients, whereas positive results of 68 Ga-DOTATATE PET/CT were in 27 (96.4%) patients. A total of 686 foci of metastatic lesions were detected by both 18 F-MFBG and 68 Ga-DOTATATE imaging. In addition, 33 foci of abnormal activity were only detected by 18 F-MFBG, whereas 16 foci were only shown on 68 Ga-DOTATATE PET/CT.

CONCLUSIONS

Our data suggest that 18 F-MFBG PET/CT is an effective imaging method in the evaluation of metastatic PPGL and could be alternative of 68 Ga-DOTATATE PET/CT in this clinical setting.

Treatment of Recurrent Nasopharyngeal Carcinoma: A Sequential Challenge

Simple Summary

Recurrent nasopharyngeal carcinoma is one of the major causes of death among NPC patients. However, there are no international guidelines for the treatment of patients with recurrent NPC now. In this article, we summarize past publications on clinical research and mechanistic studies related to recurrent NPC, combined with the experience and lessons learned by our institutional multidisciplinary team in the treatment of recurrent NPC. We propose an objective protocol for the treatment of recurrent NPC.

Abstract

Recurrent nasopharyngeal carcinoma (NPC), which occurs in 10–20% of patients with primary NPC after the initial treatment modality of intensity-modulated radiation therapy (IMRT), is one of the major causes of death among NPC patients. Patients with recurrent disease without distant metastases still have a chance to be saved, but re-treatment often carries more serious toxicities or higher risks. For this group of patients, both otolaryngologists and oncologists are committed to developing more appropriate treatment regimens that can prolong patient survival and improve survival therapy. Currently, there are no international guidelines for the treatment of patients with recurrent NPC. In this article, we summarize past publications on clinical research and mechanistic studies related to recurrent NPC, combined with the experience and lessons learned by our institutional multidisciplinary team in the treatment of recurrent NPC. We propose an objective protocol for the treatment of recurrent NPC.

Variants and Pitfalls in PET/CT Imaging of Gastrointestinal Cancers

In the past two decades, PET/CT has become an essential modality in oncology increasingly used in the management of gastrointestinal (GI) cancers. Most PET/CT tracers used in clinical practice show some degree of GI uptake. This uptake is quite variable and knowledge of common patterns of biodistribution of various radiotracers is helpful in clinical practice. 18F-Fluoro-Deoxy-Glucose (FDG) is the most commonly used radiotracer and has quite a variable uptake within the bowel. 68Ga-Prostate specific membrane antigen (PSMA) shows intense uptake within the proximal small bowel loops. 11C-methyl-L-methionine (MET) shows high accumulation within the bowels, which makes it difficult to assess bowel or pelvic diseases. One must also be aware of technical artifacts causing difficulties in interpretations, such as high attenuation oral contrast material within the bowel lumen or misregistration artifact due to patient movements. It is imperative to know the common variants and benign diseases that can mimic malignant pathologies. Intense FDG uptake within the esophagus and stomach may be a normal variant or may be associated with benign conditions such as esophagitis, reflux disease, or gastritis. Metformin can cause diffuse intense uptake throughout the bowel loops. Intense physiologic uptake can also be seen within the anal canal. Segmental bowel uptake can be seen in inflammatory bowel disease, radiation, or medication induced enteritis/colitis or infection. Diagnosis of appendicitis or diverticular disease requires CT correlation, as normal appendix or diverticulum can show intense uptake. Certain malignant pathologies are known to have only low FDG uptake, such as early-stage esophageal adenocarcinoma, mucinous tumors, indolent lymphomas, and multicystic mesotheliomas. Response assessment, particularly in the neoadjuvant setting, can be limited by post-treatment inflammatory changes. Post-operative complications such as abscess or fistula formation can also show intense uptake and may obscure underlying malignant pathology. In the absence of clinical suspicion or rising tumor marker, the role of FDG PET/CT in routine surveillance of patients with GI malignancy is not clear.

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.