Usefulness of positron emission tomography in the differentiation between tumor and infectious lesions in pediatric oncology: a case report

The utility of abdominal ultrasonography in the diagnosis of fungal infections in children: a narrative review

In paediatric patients, ultrasonography is one of the preferred medical imaging modalities due to the lack of ionising radiation. Abdominal ultrasonography can be a useful tool in diagnosing cases of fungal infections but may introduce some risks for further infection in vulnerable patients or cause anxiety and discomfort. The aim of this narrative review is to analyse the utility of abdominal ultrasonography in diagnosing fungal infections in children in terms of its positive hit rates and utility in typical use. Text words and indexed terms related to 'fungal infection and ultrasonography' and 'children' were searched on MEDLINE, EMBASE, Cochrane Library and Scopus. Paediatric oncology patients, neonates and generally immunocompromised children were found to be at-risk groups with increasing susceptibility to risk factors for contracting fungal infections. Abdominal ultrasonography was found to aid in the diagnosis of fungal infection in many cases, but not all patients with the identified risk factors were diagnosed with fungal infections and not all patients diagnosed with fungal infections had identified risk factors. Ultrasonography was found to be overutilised and the current decision process in requesting abdominal ultrasonography in diagnosing fungal infection should be revised. Further study into an effective criterion in requesting abdominal ultrasonography is suggested to reduce the overutilisation of ultrasonography, thus reducing risk of infection and discomfort while also saving time and money.

What, where and why: exploring fluorodeoxyglucose-PET's ability to localise and differentiate infection from cancer

PURPOSE OF REVIEW

To review the utility of FDG-PET imaging in detecting the cause of fever and infection in patients with cancer.

RECENT FINDINGS

FDG-PET has been shown to have high sensitivity and accuracy for causes of neutropenic fever, leading to higher diagnostic certainty in this group. Recent advances in pathogen-specific labelling in PET to identify Aspergillus spp. and Yersinia spp. infections in mice, as well as differentiating between Gram-positive, Gram-negative and mycobacterial infections are promising.

SUMMARY

Patients with cancer are vulnerable to infection and fever, and the causes of these are frequently unclear using conventional diagnostic methods leading to high morbidity and mortality, length of stay and costs of care. FDG-PET/CT, with its unique complementary functional and anatomical information as well as its whole-body imaging capability, has demonstrated use in detecting occult infection in immunocompromised patients, including invasive fungal and occult bacterial infections, as well as defining extent of infection. By demonstrating disease resolution following treatment and allowing earlier cessation of therapy, FDG-PET acts as a key tool for antimicrobial and antifungal stewardship. Limitations include at times poor differentiation between infection, malignancy and sterile inflammation, however, exciting new technologies specific to infectious pathogens may help alleviate that issue. Further prospective randomised research is needed to explore these benefits in a nonbiased fashion.

Imaging fungal infections in children

Fungal infections in children rarely occur, but continue to have a high morbidity and mortality despite the development of newer antifungal agents. It is essential for these infections to be diagnosed at the earliest possible stage so appropriate treatment can be initiated promptly. The addition of high-resolution computer tomography (HR CT) has helped in early diagnosis making; however, it lacks both sensitivity and specificity. Metabolic changes precede anatomical changes and hybrid imaging with positron emission tomography (PET) integrated with imaging modalities with high anatomical resolution such as CT or magnetic resonance imaging (MRI) is likely to detect these infections at an earlier stage with higher diagnostic accuracy rates. Several authors presented papers highlighting the advantages of PET/CT in imaging fungal infections. These papers, however, usually involve a limited number of patients and mostly adults. Fungal infections behave different in children than in adults, since there are differences in epidemiology, imaging findings, and response to treatment with antifungal drugs. This paper reviews the literature and explores the use of hybrid imaging for diagnosis and therapy decision making in children with fungal infections.