Incidental detection of thoracic sarcoidosis on whole-body 18fluorine-2- fluoro-2-deoxy-D-glucose positron emission tomography

Relationships Between Systemic Inflammatory Markers and 18F-FDG PET/CT Imaging and Clinical Findings in Pulmonary Sarcoidosis

Background and aim Sarcoidosis is a multisystem inflammatory disease of unknown aetiology. This study aimed to evaluate the relationship between systemic inflammatory parameters, the systemic immune-inflammation index (SII) and the lymphocyte-to-monocyte ratio (LMR), and disease stage, clinical findings, and 18F-fluoro-2-deoxy-D-glucose (18F-FDG) tomography/computed tomography (PET/CT) uptake. Materials and methods Our study included 73 patients. The general characteristics, radiological features, spirometric tests, PET/CT findings, and laboratory parameters of the patients were recorded. Results Relapse and parenchymal fibrosis were not associated with metabolic parameters, such as LMR and SII. Serum angiotensin-converting enzyme (ACE) levels were lower in the relapsed group than in the non-relapse group. However, the patients' PET/CT images indicated that 18F-FDG parenchym maximum standard uptake value (SUV max), lymph node SUV max, lymph node short axis dimension, SII, and LMR were similar between all patients, relapsed or not. Conclusion Although found to be significant in other inflammatory diseases, we found that SII and LMR alone did not indicate disease prognosis in sarcoidosis due to the small number of patients and the lack of homogeneity between the groups in our study. The usefulness of these markers for clinical use should be investigated by studies that include those with extrapulmonary sarcoidosis, and that calculate these markers at the time of disease diagnosis and during the post-treatment period.

18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging review of benign lesions of the thorax

2-deoxy-2-(Fluorine-18) fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) has been used exclusively to diagnose malignancies. However, increased ¹⁸F-FDG uptake is not always limited to malignant lesions. This imaging review demonstrates the physiological ¹⁸F-FDG uptake of normal structures in the thorax and illustrates many benign pathological lesions with standardized uptake value >2.5. These various conditions can be broadly categorized into three groups: infective lesions, active granulomatous diseases such as sarcoidosis, noninfectious/inflammatory, or proliferative conditions such as radiation pneumonitis, postlung transplant lymphoproliferative disorders, occupational pleuropulmonary complications, and postsurgical conditions, all of which can demonstrate varying degrees of ¹⁸F-FDG uptake on PET/CT based upon the degree of inflammatory activity. Familiarity of false-positive findings improves the PET/CT evaluation accuracy of benign lesions of the thorax. Radiation exposure and surgical history correlation along with imaging cross check evaluation of radiographs and magnetic resonance images for the anatomic location remains the mainstay of PET/CT characterization of positive findings.

Sarcoidosis: sex-dependent variations in presentation and management

Sarcoidosis is an inflammatory disease with a wide range of clinical presentations. The manifestations and prognosis in sarcoidosis are dependent upon not only organ involvement but also age and sex. The purpose of this review is to describe the systemic and ocular manifestations of sarcoidosis with a specific focus on sex-dependent difference in presentation and management. Sarcoidosis is more common in women, particularly in patients who present after age of 50 years. Women with sarcoidosis are more likely to develop cystoid macular edema and the mortality rate is higher than that of men.

PET/CT in Patients with Sarcoidosis or IgG4 Disease

Sarcoidosis as a distinct disease entity was diagnosed more than 100 years ago. The signs and symptoms of the disease are nonspecific, posing a challenge for early and accurate diagnosis. IgG4 disease or syndrome has various clinical manifestations, such as sclerosing pancreatitis, sclerosing cholangitis, prostatitis, tubulointerstitial nephritis, interstitial pneumonia, and enlargement of salivary glands. This article discusses the role of the different diagnostic imaging modalities in sarcoidosis and IgG4 disease, including radiographs, computed tomography, magnetic resonance imaging, and conventional nuclear medicine, with a special emphasis on positron emission tomography as a superior modality for assessing these inflammatory diseases.

Mediastinal hibernoma simulates a malignant lesion on dual time point FDG imaging

Dual time point 2-deoxy-2-[18F] fluoro-d-glucose (FDG) positron emission tomography (PET) imaging has been shown to be useful in helping differentiate benign from malignant lesions. An enhancing mediastinal mass of fat and water density was incidentally detected on computed tomography (CT) in a patient being evaluated for thoracic trauma. He subsequently underwent dual time point FDG PET/CT imaging which revealed a significant rise in standard uptake value (SUV) within the lesion over time, favoring a malignant etiology. Biopsy proved the lesion to represent a hibernoma, an uncommon benign fatty tumor. This case exemplifies the complexity of tissue metabolic properties, and the difficulty in establishing absolute criteria for benign and malignant processes.

Unsuspected FDG–PET findings in the follow-up of patients with lymphoma

18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET) plays an increasing role in the management of patients with lymphoma, for which it is successfully used for staging and treatment monitoring. We report seven patients with a history of lymphoma who presented a positive FDG-PET suggestive of lymphoma relapse and for which FDG-PET oriented biopsies revealed alternative diagnoses. Early in lymphoma follow-up, persistence of focal increased FDG activity corresponded to inflammatory or infectious lesions in two patients: one aspergillosis and one sarcoidosis. Later in the follow-up, five cases of secondary malignancies were identified (three lung cancers, one epidermoid carcinoma, and one villous tumor) in this particularly exposed population. The routine use of FDG PET to evaluate lymphoma significantly increases the probability of detecting unexpected diseases. These cases illustrate the potential pitfalls in PET follow-up. Because FDG is not lymphoma-specific, a relapse suspected only on FDG-PET imaging requires biopsy, as alternative diagnoses--infectious or malignant--are possible. Our data draws clinician's attention to potential false-positive FDG-PET findings, which may lead to therapeutic mistakes. Our data also suggests that FDG-PET might be a new imaging modality for long-term monitoring of late effects, especially second cancer occurrence.

Simple pulmonary eosinophilia evaluated by means of FDG PET: the findings of 14 cases

Objective

We wanted to describe the findings of simple pulmonary eosinophilia with using 18 fluorodeoxyglucose (FDG) positron emission tomography (PET).

Materials and Methods

We analysed the findings of 14 patients who underwent thoracic computed tomography (CT) and PET, and then they were subsequently proven to have simple pulmonary eosinophilia. PET studies were performed in four patients with malignancy to evaluate for cancer metastasis, and PET scans were also done in 10 healthy subjects who underwent volunteer cancer screening. The PET scans were evaluated by using the maximum standardized uptake values (SUVs). The subjects' CT findings also were reviewed and correlated with the PET findings.

Results

A total of 42 nodules were detected on the CT scans. There were single nodules in three patients and multiple nodules in 11 patients (mean number of nodules: 3, range: 1-10, mean diameter: 9.5 mm ± 4.7). Twelve of 42 (28.6%) nodules showed FDG uptake and their mean maximum SUV was 2.5 ± 1.6 (range: 0.6-5.3). Five of six solid nodules showed FDG uptake (2.2 ± 1.1, range: 0.9-3.6), six of 11 semisolid nodules showed FDG uptake (3.1 ± 1.8, range: 0.6-5.3) and one of 25 pure ground-glass opacity nodule showed a maximum SUV of 0.8. The maximum SUVs of seven nodules in five patients were greater than 2.5. The maximum SUVs were significantly different according to the nodule types (p < 0.001).

Conclusion

Simple pulmonary eosinophilia commonly causes an increase in FDG uptake. Therefore, correlation of the PET findings with the CT findings or the peripheral eosinophil counts can help physicians arrive at the correct diagnosis of simple pulmonary eosinophilia.

State-of-the-art FDG-PET imaging of lung cancer

The D-glucose analog 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (FDG) is the most commonly used radionuclide in positron emission tomography (PET) of lung cancer. FDG-PET is a molecular imaging technique that images the preferential accumulation of FDG in malignant tissues with increased metabolism. Although FDG-PET is sensitive in the detection of lung cancer, FDG is not tumor specific and may accumulate in a variety of nonmalignant conditions. Occasional false-negative results may also occur. Whole body FDG-PET is a useful noninvasive technique to stage known or suspected non-small-cell lung cancer. The results allow more efficient use of invasive methods for histopathological staging. The combined use of CT and PET in dual imaging increases the number of patients with correctly staged non-small-cell lung cancer. CT/PET is also useful in the assessment of recurrent or residual disease. Future imaging agents are being developed which may allow more selective accumulation of radiopharmaceutical in malignant tissues.

Applications of fluorodeoxyglucose-PET imaging in the detection of infection and inflammation and other benign disorders

FDG-PET has great potential in the evaluation of a variety of inflammatory and infectious disorders and possibly other benign disorders. FDG-PET is very helpful in the evaluation of chronic osteomyelitis, sarcoidosis, FUO, and differentiating toxoplasmosis from lymphoma in the central nervous system in HIV-positive patients. The assessment of efficacy of FDG-PET in the evaluation of arthroplasty-associated infection, large-vessel vasculitis, and other inflammatory and infectious disorders is ongoing but seems quite promising at this time.

Fluorodeoxyglucose PET Scan in Pulmonary Sarcoidosis during Treatment with Inhaled and Oral Corticosteroids

The objective was to investigate longitudinal changes in fluorodeoxyglucose PET scan (FDG-PET) in a patient with pulmonary sarcoidosis prior to and during treatment with inhaled corticosteroids followed by systemic corticosteroids. The patient was a 41-year-old man presenting with stage I pulmonary sarcoidosis (hilar adenopathy), which had progressed to stage II (pulmonary infiltrates) 19 months later. FDG-PET was performed at 19, 29 and 33 months after presentation. No treatment was given prior to the 1st PET. Subsequently, before the 2nd PET, the patient was treated with inhaled beclomethasone (QVAR Autohaler) 0.8 mg/day for 8 months. Finally, prior to the 3rd PET, the patient was treated with oral prednisolone 30 mg/day for 3 months. The 1st PET showed a high FDG uptake in the hilar and mediastinal lymph nodes and a high focal uptake in the peripheral parts of the lungs. The 2nd PET showed a slight uptake in a few mediastinal lymph nodes and an unchanged high focal uptake in the peripheral parts of the lungs and the pleura. The 3rd PET showed no abnormal uptake at all. In conclusion, as assessed by FDG-PET, inhaled beclomethasone had no recognizable influence on sarcoid inflammatory activity. Treatment with oral prednisolone depressed the inflammatory activity to such a degree that it was undetectable by PET. The results are in accordance with clinical studies on pulmonary sarcoidosis, showing a marginal effect of inhaled corticosteroids and a marked effect of systemic corticosteroids.

Positron emission tomography imaging in nonmalignant thoracic disorders

The role of the fluorodeoxyglucose (FDG) technique positron emission tomography (PET) is well established in the management of patients with lung cancer. Increasingly, it is becoming evident that FDG-PET can be effectively employed to diagnose a variety of benign pulmonary disorders. Knowledge of such applications further expands the domain of this powerful modality and further improves the ability to differentiate benign from malignant diseases of the chest. We describe pertinent technical factors that substantially contribute to optimal imaging of the thoracic structures. Particularly, the complementary role of attenuation correction (AC) to that of non-AC images is emphasized. We further outline the need for and the state of the art for co-registration of PET and anatomic images for diagnostic and therapeutic purposes. We then review patterns of physiologic uptake of FDG in thoracic structures, including the lung, the heart, the aorta and large arteries, esophagus, thymus, trachea, thoracic muscles, bone marrow, and joints and alterations following radiation therapy to the thorax. A great deal of information is provided with regard to differentiating benign from malignant nodules and in particular, we emphasize the role of dual time point imaging and partial volume correction for accurate assessment of such lesions. Following a brief review of the diagnostic issues related to the assessment of mediastinal adenopathies, the role of FDG-PET imaging in environment-induced lung diseases, including pneumoconiosis, smoking, and asthma are described. A large body of information is provided about the role of this technology in the management of patients with suspected infection and inflammation of the lungs such as acquired immunodeficiency syndrome, fever of unknown origin, sarcoidosis, chronic granulomatous disease and monitoring the disease process and response to therapy. Finally, the value of FDG-PET in differentiating benign from malignant diseases of the pleura including asbestosis-related disorders is described at the conclusion of this comprehensive review.

18-fluorodeoxyglucose positron emission tomographic imaging in the detection and monitoring of infection and inflammation

During the past decade, 18-fluorodeoxyglucose (FDG) positron emission tomography (PET) has rapidly evolved from a pure research modality to a clinical necessity. FDG-PET was introduced to determine the state of brain function in physiologic and pathologic states. Its use as a powerful tool to diagnose, stage, and monitor patients with a variety of malignancies has been truly revolutionary. However, FDG is a nonspecific tracer and it has been found to accumulate at sites of infection and inflammation. It is becoming evident that PET imaging will play a major role in the treatement of patients with suspected infection and inflammation. PET has been shown to be particularly valuable in the evaluation of chronic osteomyelitis, infected prostheses, sarcoidosis, fever of unknown origin, and acquired immunodeficiency syndrome. Because of its ability to quantitate the rate of FDG uptake, PET may prove to be a powerful modality for the monitoring of disease activity and response to therapy. Novel PET tracers are being tested for imaging infection and inflammation that may further enhance the role of this technique in the appropriate clinical setting. PET imaging to detect and characterize infection and inflammation may become a major clinical indication in the day-to-day practice of medicine.

Sarcoidosis presenting as an enlarging solitary pulmonary nodule

Sarcoidosis is generally not considered in the differential diagnosis of solitary pulmonary nodules. We recently encountered a case in which preoperative awareness of this presentation of sarcoidosis allowed a limited pulmonary resection with resultant lower morbidity and potential preservation of lung function to be performed. Although rare, sarcoidosis should be considered in the differential diagnosis of solitary pulmonary nodules.