Malignant disease as an incidental finding at ¹⁸F-FDG-PET/CT scanning in patients with granulomatous lung disease

Immune PET Imaging

Fluorodeoxyglucose (FDG) PET/CT is sensitive to metabolic, immune-related, and structural changes that can occur in tumors in cancer immunotherapy. Unique mechanisms of immune checkpoint inhibitors (ICIs) occasionally make response evaluation challenging, because tumors and inflammatory changes are both FDG avid. These response patterns and sequelae of ICI immunotherapy, such as immune-related adverse events, are discussed. Immune-specific PET imaging probes at preclinical stage or in early clinical trials, which may help guide clinical management of cancer patients treated with immunotherapy and likely have applications outside of oncology for other diseases in which the immune system plays a role, are reviewed.

Characterization of 18F-fluorodeoxyglucose metabolic spatial distribution improves the differential diagnosis of indeterminate pulmonary nodules and masses with high fluorodeoxyglucose uptake

Background

The aim of this study was to investigate the value of visual assessment of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) metabolic spatial distribution (V-FMSD) in the diagnosis of indeterminate pulmonary nodules and masses with high ¹⁸F-FDG uptake.

Methods

A total of 301 patients with indeterminate pulmonary nodules or masses who underwent ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) imaging were retrospectively studied. The characteristics of ¹⁸F-FDG metabolic spatial distribution (FMSD) in the proximal and distal regions of the lesions were visually analyzed using a 5-point scoring system. The sensitivity, specificity, accuracy, and area under receiver operating characteristic curve (AUC) were compared between V-FMSD and conventional PET/CT methods for the diagnosis of hypermetabolic indeterminate pulmonary nodules and masses.

Results

The V-FMSD results showed that 180 (92.8%) malignant lesions had a score of ≥3 and 78 (72.9%) benign lesions had a score of ≤2. This indicated that the FMSD in the proximal region of malignant lesions was significantly higher than that of the distal region, and the FMSD in the proximal region of benign lesions was significantly lower than that of the distal region. V-FMSD had a specificity of 72.9%, which was markedly higher than those of the maximum standard uptake value (SUV_max; 0%, P<0.001) and the retention index (RI; 26.2%, P<0.001). The AUC of V-FMSD was 0.886, which was significantly larger than those of the SUV_max (0.626, P<0.001), RI (0.670, P<0.001), and PET/CT (0.788, P<0.05).

Conclusions

Our study found that pulmonary benign and malignant lesions have distinct FMSD characteristics. V-FMSD can therefore be used as a novel auxiliary marker to improve the diagnostic accuracy of hypermetabolic indeterminate pulmonary nodules and masses.

Lung Cancer Screening, Version 3.2018, NCCN Clinical Practice Guidelines in Oncology

Lung cancer is the leading cause of cancer-related mortality in the United States and worldwide. Early detection of lung cancer is an important opportunity for decreasing mortality. Data support using low-dose computed tomography (LDCT) of the chest to screen select patients who are at high risk for lung cancer. Lung screening is covered under the Affordable Care Act for individuals with high-risk factors. The Centers for Medicare & Medicaid Services (CMS) covers annual screening LDCT for appropriate Medicare beneficiaries at high risk for lung cancer if they also receive counseling and participate in shared decision-making before screening. The complete version of the NCCN Guidelines for Lung Cancer Screening provides recommendations for initial and subsequent LDCT screening and provides more detail about LDCT screening. This manuscript focuses on identifying patients at high risk for lung cancer who are candidates for LDCT of the chest and on evaluating initial screening findings.

Improving the rates of Aspergillus detection: an update on current diagnostic strategies

INTRODUCTION

The spectrum of disease caused by Aspergillus spp. is dependent on the immune system of the host, and ranges from invasive aspergillosis (IA) to chronic pulmonary aspergillosis (CPA). Early and reliable diagnosis of Aspergillus disease is important to decrease associated morbidity and mortality. Areas covered: The following review will give an update on current diagnostic strategies for the diagnosis of IA and CPA. Expert commentary: Several new diagnostics for IA (including point-of-care tests) are now available to complement galactomannan testing. In particular, immunoPET/MRI imaging may be a promising approach for diagnosing IA in the near future. Notably, nearly all new biomarkers and tests for IA have been evaluated in the hematology setting only. Validation of biomarkers and tests is therefore needed for the increasing proportion of patients who develop IA outside the hematology setting. As an important first step, reliable definitions of IA are needed for non-hematology settings as clinical presentation and radiologic findings differ in these settings. CPA diagnosis is based on a combination of radiological findings in chest CT, mycological evidence (e.g. by the Aspergillus-specific IgG assay), exclusion of alternative diagnosis and chronicity. ([18F]FDG) PET/CT and immuno PET/MRI imaging are promising new imaging approaches.

Differential diagnosis of granulomatous lung disease: clues and pitfalls

Granulomatous lung diseases are a heterogeneous group of disorders that have a wide spectrum of pathologies with variable clinical manifestations and outcomes. Precise clinical evaluation, laboratory testing, pulmonary function testing, radiological imaging including high-resolution computed tomography and often histopathological assessment contribute to make a confident diagnosis of granulomatous lung diseases. Differential diagnosis is challenging, and includes both infectious (mycobacteria and fungi) and noninfectious lung diseases (sarcoidosis, necrotising sarcoid granulomatosis, hypersensitivity pneumonitis, hot tub lung, berylliosis, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, rheumatoid nodules, talc granulomatosis, Langerhans cell histiocytosis and bronchocentric granulomatosis). Bronchoalveolar lavage, endobronchial ultrasound-guided transbronchial needle aspiration, transbronchial cryobiopsy, positron emission tomography and genetic evaluation are potential candidates to improve the diagnostic accuracy for granulomatous lung diseases. As granuloma alone is a nonspecific histopathological finding, the multidisciplinary approach is important for a confident diagnosis.

A multidisciplinary approach is crucial for the accurate differential diagnosis of granulomatous lung diseaseshttp://ow.ly/FxsP30cebtf

18F-FDG PET/CT in the Initial Assessment and for Follow-up in Patients With Tuberculosis

PURPOSE

The aim of this retrospective study was to assess the value of 18F-FDG PET/CT in the initial evaluation and follow-up of patients with tuberculosis (TB).

PATIENTS AND METHODS

Thirty-five patients (18 men) with pulmonary or extrapulmonary TB were included. Diagnosis of TB was based either on histology or microbiological assessment in 32 patients and was based on typical morphological features of TB in CT and improvement on antimycobacterial medication in 3 patients. Eighty-eight 18F-FDG PET/CT scans were performed at initial assessment and during treatment, on a Siemens Biograph PET/CT. Diagnostic contrast-enhanced CT scans were performed on the 40-slice multidetector CT of the PET/CT scanner. Mean (SD) anti-TB treatment duration was 16.1 (8.9) months.

RESULTS

The initial 18F-FDG PET identified 64 affected regions in 34 among 35 patients, whereas CT identified 34 affected organs in 23 patients. Matching image results between PET and CT were observed at first visit in 11 patients (31.4%), with relevant differences in 23 (65.7%). In 1 patient, both modalities remained negative. During follow-up 18F-FDG PET scans, we recorded 15 cases with remission of disease, 16 with residual disease (2 patients with multidrug-resistant infection), and 4 cases with progressive disease or delayed onset of adequate immunological response. In only 3 patients, both modalities, PET and CT, showed completely equivalent results.

CONCLUSIONS

Both components of 18F-FDG PET/CT provide complementary information at initial evaluation and during follow-up; however, 18F-FDG showed more abnormal findings than CT. 18F-FDG PET/CT might be useful for the establishment of individualized treatment regimes, but this requires further prospective studies.

The role of endobronchial ultrasonography for mediastinal lymphadenopathy in cases with extrathoracic malignancy

INTRODUCTION

Many extrathoracic malignancies can metastasize to lungs and mediastinal lymph nodes. Whether mediastinal lesions are metastasis in these patients changes staging, prognosis, and treatment strategy. In this study, we aimed to find out the contribution of EBUS-TBNA to the diagnosis in cases with extrathoracic malignancy.

MATERIALS AND METHODS

Patients who had been previously diagnosed as extrapulmonary solid organ malignancy and in whom mediastinal or hilar lymphadenopathy developed during their follow-up and EBUS-TBNA was applied for diagnostic purposes were retrospectively included in this study.

RESULTS

A total of 91 patients consisting of 35 females (38.5 %) and 56 males (61.5 %) were included in the study. The mean age of the patients was 60.5 (±11.4). Malignancy was not observed in 54 (59.3 %) patients; primary malignancy metastasis was detected in 33 (36.3 %) patients, and primary lung cancer was detected in 4 (4.4 %) patients with EBUS-TBNA. The sensitivity of EBUS-TBNA in extrathoracic malignancies was determined as 90.2 %; its specificity was determined as 100 %, its negative predictive value as 92.5 %, its positive predictive value as 100 %, and its diagnostic accuracy as 95.6 %. The highest rate was determined in the left lower paratracheal lymph node when they were examined in terms of malignancy detection rate in lymph node stations.

CONCLUSION

EBUS-TBNA is a minimally invasive method with quite a low complication rate that does not require general anesthesia. It should be the first step method to be used in the diagnosis of mediastinal and hilar lymphadenopathies seen in extrathoracic malignancies since it has high diagnostic accuracy, sensitivity, and specificity. EBUS-TBNA significantly reduces the need for surgical intervention. Further surgical interventions can be planned in patients in whom diagnostic competence is not ensured.

PET/CT imaging of Mycobacterium tuberculosis infection

Tuberculosis has a high morbidity and mortality worldwide. Mycobacterium tuberculosis (Mtb) has a complex pathophysiology; it is an aerobic bacillus capable of surviving in anaerobic conditions in a latent state for a very long time before reactivation to active disease. In the latent tuberculosis infection, the individual has no clinical evidence of active disease, but exhibits a hypersensitive response to proteins of Mtb. Only some 5–10 % of latently infected individuals appear to have reactivation of tuberculosis at any one time point after infection, and neither imaging nor immune tests have been shown to predict tuberculosis reactivation reliably. The complex pathology of the organism provides multiple molecular targets for imaging the infection and targeting therapy. Positron emission tomography (PET) integrated with computer tomography (CT) provides a unique opportunity to noninvasively image the whole body for diagnosing, staging and assessing therapy response in many infectious and inflammatory diseases. PET/CT is a powerful noninvasive tool that can rapidly provide three-dimensional views of disease deep within the body and conduct longitudinal assessment over time in one particular patient. Some PET tracers, such as ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG), have been found to be useful in various infectious diseases for detection, assessing disease activity, staging and monitoring response to therapy. This tracer has also been used for imaging tuberculosis. ¹⁸F-FDG PET relies on the glucose uptake of inflammatory cells as a result of the respiratory burst that occurs with infection. Other PET tracers have also been used to image different aspects of the pathology or microbiology of Mtb. The synthesis of the complex cell membrane of the bacilli for example can be imaged with ¹¹C-choline or ¹⁸F-fluoroethylcholine PET/CT while the uptake of amino acids during cell growth can be imaged by 3′-deoxy-3′-[¹⁸F]fluoro-l-thymidine. PET/CT provides a noninvasive and sensitive method of assessing histopathological information on different aspects of tuberculosis and is already playing a role in the management of tuberculosis. As our understanding of the pathophysiology of tuberculosis increases, the role of PET/CT in the management of this disease would become more important. In this review, we highlight the various tracers that have been used in tuberculosis and explain the underlying mechanisms for their use.