Assessment of Suspected Malignancy or Infection in Immunocompromised Patients After Solid Organ Transplantation by [18F]FDG PET/CT and [18F]FDG PET/MRI

Algorithmic Approach to an Abnormal Computed Tomography of the Chest in the Immunocompromised Host

The immunocompromised host is a patient who is at risk for life threatening complications. This article offers a structured approach to interpreting abnormal chest computed tomography (CT) scans in these patients. Immune defects are categorized as innate or adaptive and each is linked to specific infectious risks. CT scan findings are grouped into 5 categories: nodules and/or masses, consolidation or ground glass opacity, large airway abnormalities, pleural effusions, and lymphadenopathy. This algorithmic approach can guide clinicians in establishing a differential diagnosis for immunocompromised patients with abnormal chest CT scans and help them reach a faster and more accurate diagnosis.

Rheumatoid arthritis complicated with cervical actinomycosis and ureteral obstruction: A case report and literature review

Actinomycosis is a rare chronic granulomatous disease characterized by granuloma formation and tissue fibrosis with sinus tracts, often misdiagnosed due to its similarity to many infectious and non-infectious diseases. This report presents a case of a 60-year-old female with more than 10 years history of rheumatoid arthritis who developed actinomycosis infection after long-term treatment with immunosuppressants and biologics, including methotrexate, leflunomide, and infliximab, leading to recurrent joint pain, poorly controlled rheumatoid arthritis activity, and persistent elevation of white blood cell counts. Abdominal CT revealed a pelvic mass and right ureteral dilation. Pathological examination of cervical tissue showed significant neutrophil infiltration and sulfur granules, indicating actinomycosis. The patient received 18 months of doxycycline treatment for the infection and continued rheumatoid arthritis therapy with leflunomide, hydroxychloroquine sulfate, and tofacitinib, resulting in improved joint symptoms and normalized white blood cell counts. After 2 years of follow-up, the patient remained stable with no recurrence. This case highlights the importance of clinicians being vigilant for infections, particularly chronic, occult infections from rare pathogens, in rheumatoid arthritis patients on potent immunosuppressants and biologics, advocating for early screening and diagnosis.

[18F]FDG PET/CT Findings of Mass-Forming Actinomycosis in an Uncontrolled Diabetic Patient

We report a case of cervicofacial actinomycosis mimicking malignant sarcoma in a 78-year-old man with diabetes. High lesion uptake and decreased cerebral uptake on [18F]FDG PET/CT provide a potentially important diagnostic clue suggesting infectious disease in a poorly controlled diabetic patient.

The progress of PET/MRI in clinical management of patients with pancreatic malignant lesions

Recently, the morbidity and mortality of pancreatic cancer have been increasing year by year. Because of its deep anatomical location and because most presented patients often suffer from abdominal pain or jaundice, it is difficult to diagnose pancreatic cancer at an early stage, leading to late clinical stage and poor prognosis. integrated positron emission tomography/magnetic resonance imaging (PET/MRI) fusion imaging not only has the characteristics of high resolution and multi-parameter imaging of MRI, but also combines the high sensitivity and the semi-quantitative characteristics of PET. In addition, the continuous development of novel MRI imaging and PET imaging biomarkers provide a unique and precise research direction for future pancreatic cancer research. This review summarizes the value of PET/MRI in the diagnosis, staging, efficacy monitoring, and prognosis evaluation of pancreatic cancer, and prognosis for developing emerging imaging agents and artificial intelligence radiomics in pancreatic cancer.

FDG PET/CT to Detect Incidental Findings in Patients With Hepatocellular Carcinoma-Additional Benefit for Patients Considered for Liver Transplantation?

PURPOSE

FDG PET/CT has been described for noninvasive grading, detection of extrahepatic spread, and recurrence in hepatocellular carcinoma (HCC). As compared with localized imaging approaches (MRI, ultrasonography), FDG PET/CT not only focuses on the liver, but covers a long field of view from the base of the skull to the thighs, visualizing pathologic findings not related to HCC. The aims of this retrospective study were to (1) describe the frequency of relevant incidental findings on FDG PET/CT in HCC patients, (2) evaluate the impact on treatment strategy in HCC patients considered for liver transplantation, and (3) to discuss the role of FDG PET/CT in patients considered for transplantation in general.

METHODS

Four hundred thirty-nine FDG PET/CT examinations of 345 HCC patients were screened for incidental findings. The clinical information system was searched for examinations performed after FDG PET/CT and aimed at verification of incidental findings. Of 345 HCC patients, 81 patients were considered for liver transplantation. The impact of incidental findings was recorded separately for this subgroup.

RESULTS

One hundred one patients with incidental findings in 439 FDG PET/CT examinations were identified. The incidental findings comprised 22 neoplasms (9 malignant) and 52 inflammations. Liver transplantation was not performed because of an incidental finding on FDG PET/CT in 9 (11.1%) of 81 patients.

CONCLUSIONS

FDG PET/CT is capable of identifying relevant incidental findings (ie, secondary malignancy, benign tumors, and inflammation) in HCC patients and HCC patients considered for liver transplantation and thus influencing HCC patient management. FDG PET/CT might also be beneficial in patients considered for transplantation of different organs.

18F-FDG PET/CT for Evaluation of Post-Transplant Lymphoproliferative Disorder (PTLD)

Post-transplant lymphoproliferative disorders (PTLD) are a spectrum of heterogeneous lymphoproliferative conditions that are serious and possibly fatal complications after solid organ or allogenic hematopoietic stem cell transplantation. Most PTLD are attributed to Epstein-Barr virus reactivation in B-cells in the setting of immunosuppression after transplantation. Early diagnosis, accurate staging, and timely treatment are of vital importance to reduce morbidity and mortality. Given the often nonspecific clinical presentation and disease heterogeneity of PTLD, tissue biopsy and histopathological analysis are essential to establish diagnosis and most importantly, determine the subtype of PTLD, which guides treatment options. Advanced imaging modalities such as ¹⁸F-FDG PET/CT have played an increasingly important role and have shown high sensitivity and specificity in detection, staging, and assessing treatment response in multiple clinical studies over the last two decades. However, larger multicenter prospective validation is still needed to further establish the clinical utility of PET imaging in the management of PTLD. Significantly, new hybrid imaging modalities such as PET/MR may help reduce radiation exposure, which is especially important in pediatric transplant patients.

FDG PET/CT for Detection of Infectious Complications Following Solid Organ Transplantation

Infectious complications after solid organ transplantation (SOT) are often more severe and remain a diagnostic challenge due to vague and atypical clinical presentations. Diagnostic performance of conventional diagnostic tools is frequently inadequate which may lead to delayed diagnosis with the risk of poorer outcomes. This literature review aimed to investigate the current evidence on the use of ¹⁸F-fluoro-deoxy-glucose (FDG) Positron Emission Tomography (PET)/computer tomography (CT) in infectious complications after SOT. Based on search in PubMed, Medline, and Cochrane databases, 13 articles and 46 case reports were included. For inclusion, articles were to include data on patients with infectious complications after SOT, and where FDG PET/CT was part of the work-up. Final searches were conducted on 02 September 2020. Overall, in the absence of initial diagnostic clues, FDG PET/CT should be considered as the imaging technique of choice as it may guide further investigations and eventually reveal the diagnosis in most of the patients. However, the available literature of the role of FDG PET/CT in SOT recipients with infectious complications is scarce and well-designed prospective studies including control groups are warranted to establish the role of FDG PET/C/ in SOT recipients. The main drawback of FDG PET/CT is the lack of ability to differentiate between cancer and infectious diseases which are both highly prevalent in this patient group. Accordingly, the main reasons for "false" results of FDG PET/CT is the misdiagnosis of cancer in benign inflammatory or infectious processes, information which nonetheless can be useful.