Sarcoidosis Demonstrated by FDG PET Imaging With Negative Findings on Gallium Scintigraphy

Monitoring the Therapy of Extensive Osseous Sarcoidosis With FDG PET/CT

FDG PET/CT was performed in a 47-year-old man to evaluate possible malignancy of the spine revealed by MRI. The PET images revealed numerous focal FDG activity throughout the skeletal system. In addition, multiple foci of the increased activity in the mediastinal and hilar nodes were noted, suggestive of sarcoidosis, which was proven following biopsy. Therapy for sarcoidosis was initiated. In the subsequent 4 follow-up FDG PET/CT scans, the activity in both the bones and mediastinal/hilar regions fluctuated. However, anatomical abnormality in the bones on the CT images was never visualized during the entire clinical course.

Biomarkers in sarcoidosis

INTRODUCTION

Numerous biomarkers have been evaluated for the diagnosis, assessment of disease activity, prognosis, and response to treatment in sarcoidosis. In this report, we discuss the clinical and research utility of several biomarkers used to evaluate sarcoidosis. Areas covered: The sarcoidosis biomarkers discussed include serologic tests, imaging studies, identification of inflammatory cells and genetic analyses. Literature was obtained from medical databases including PubMed and Web of Science. Expert commentary: Most of the biomarkers examined in sarcoidosis are not adequately specific or sensitive to be used in isolation to make clinical decisions. However, several sarcoidosis biomarkers have an important role in the clinical management of sarcoidosis when they are coupled with clinical data including the results of other biomarkers.

Growing applications of FDG PET-CT imaging in non-oncologic conditions

As the number of clinical applications of 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET-CT) grows, familiarity with the conditions that can be diagnosed by this modality and when relevant pieces of additional information can be obtained becomes increasingly important for both requesting physicians and nuclear medicine physicians or radiologists who interpret the findings. Apart from its heavy use in clinical oncology, FDG PET-CT is widely used in a variety of non-oncologic conditions interconnecting to such disciplines as general internal medicine, infectious diseases, cardiology, neurology, surgery, traumatology, orthopedics, pediatrics, endocrinology, rheumatology, psychiatry, neuropsychology, and cognitive neuroscience. The aim of this review was to summarize the current evidence of FDG PET-CT applications in evaluating non-oncologic pathologies and the relevant information it can add to achieve a final diagnosis.

Positron emission tomography imaging in sarcoidosis

Sarcoidosis is a chronic granulomatous disease of unknown origin. There are several modalities for diagnosis, staging and therapeutic management of patients with sarcoidosis. Among these, whole-body F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography is found to useful in patients with complex and multisystem forms of sarcoidosis. Other modalities include Gallium scanning, assesment of angiotensin converting enzyme levels in blood, chest radiography, mediastinoscopy etcetera.

The scar sign: a useful finding on FDG PET/CT to distinguish sarcoidosis from other causes of lymphadenopathy

Scar involvement is a rare but characteristic cutaneous manifestation of sarcoidosis. The concurrent presence of FDG-avid lymphadenopathy and scar involvement (the "scar sign") is a useful finding on FDG PET/CT to suggest sarcoidosis, especially when biopsy specimens are difficult to obtain. A 46-year-old woman who presented with fever, cough, and weight loss was found to have mediastinal and hilar lymphadenopathy on chest radiography and CT scan. FDG PET/CT scan showed FDG-avid lower cervical, mediastinal, hilar, and inguinal lymphadenopathy. There was also increased FDG uptake along an old hysterectomy scar. Mediastinoscopy and nodal biopsy revealed noncaseating granulomas compatible with sarcoidosis.

Earlier detection of bone metastases from pleomorphic liposarcoma in a pediatric patient by FDG PET/CT than planar 99mTc MDP bone scan

Bone scintigraphy using (99m)TC MDP (technetium-99m methylene diphosphonate) is a routine procedure for evaluation of osteoblastic metastases; however, its sensitivity compared with FDG PET/CT in a variety of malignancies remains to be established. We report a case of multiple osseous metastases revealed by FDG PET/CT in an 8-year-old girl with pleomorphic liposarcoma. Many of these osseous lesions were not visualized on the MDP planar bone scintigraphy performed 24 hours after PET/CT scan, becoming evident only on repeat bone scan performed 3 months later. The case suggests that FDG PET/CT has higher sensitivity in detecting osteoblastic metastases in pleomorphic liposarcoma.

¹⁸F-FDG uptake by spleen helps rapidly predict the dose level after total body irradiation in a Tibetan minipig model

OBJECTIVES

To investigate whether (18)F- FDG uptake can be applied in dosimetry to facilitate the rapid and accurate evaluation of individual radiation doses after a nuclear accident.

METHODS

Forty-eight Tibetan minipigs were randomised into a control group (n = 3) and treatment groups (n = 45). (18)F-FDG combined positron-emission tomography and computed tomography (PET/CT) were carried out before total body irradiation (TBI) and at 6, 24 and 72 h after receiving TBI doses ranging from 1 to 11 Gy. Spleen tissues and blood samples were also collected for histological examination, apoptosis and blood analysis.

RESULTS

Mean standardised uptake values (SUVs) of the spleen showed significant differences between the experimental and the control groups. Spleen SUV at 6 h post-irradiation showed significant correlation with radiation dose; Spearman's correlation coefficient was 0.97 (P < 0.01). Histological observations showed that damage to the splenic lymphocyte became more severe with an increase in the radiation dose. Moreover, apoptosis was one of the major routes of splenic lymphocyte death, which was also confirmed by flow cytometry analysis.

CONCLUSIONS

In the Tibetan minipig model, radiation doses have a close relationship with the (18)F-FDG uptake of the spleen. This finding suggests that (18)F-FDG PET/CT may be useful for the rapid detection of individual radiation doses.

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.

Lung imaging in asthmatic patients: the picture is clearer

Imaging of the lungs in patients with asthma has evolved dramatically over the last decade with sophisticated techniques, such as computed tomography, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography. New insights into current and future modalities for imaging in asthmatic patients and their application are discussed to potentially shed a clearer picture of the underlying pathophysiology of asthma, especially severe asthma, and the proposed clinical utility of imaging in patients with this common disease.

Imaging of inflammation by PET, conventional scintigraphy, and other imaging techniques

Nuclear medicine imaging procedures play an important role in the assessment of inflammatory diseases. With the advent of 3-dimensional anatomic imaging, there has been a tendency to replace traditional planar scintigraphy by CT or MRI. Furthermore, scintigraphic techniques may have to be combined with other imaging modalities to achieve high sensitivity and specificity, and some may require time-consuming labeling procedures. On the other hand, new developments such as combined SPECT/CT increase the diagnostic power of scintigraphy. Also, the advent of PET had a considerable impact on the use of nuclear medicine imaging techniques. In this review, we aim to provide nuclear medicine specialists and clinicians with the relevant information on rational and efficient use of nuclear medicine imaging techniques in the assessment of patients with osteomyelitis, infected vascular prostheses, metastatic infectious disease, rheumatoid arthritis, vasculitis, inflammatory bowel disease, sarcoidosis, and fever of unknown origin.

Early documentation of therapeutic response at 6 weeks following corticosteroid therapy in extensive sarcoidosis: promise of FDG-PET

A 52-year-old man, who was treated with antitubercular drugs for 1 year without any benefit for an initial diagnosis of tuberculosis, and was referred for further evaluation. An FDG-PET study was performed to evaluate the whole-body disease status, which showed multiple abnormal foci in bilateral neck nodes, mediastinal, axillary, and multiple abdominal (para-aortic and inguinal) nodes, and the liver, spleen, and thyroid. A rebiopsy of the inguinal nodes for a definitive diagnosis was confirmatory of sarcoidosis. He had a history of hypothyroidism, which is a frequent accompaniment of sarcoidosis due to the association of autoimmunity in this population. He was treated with oral corticosteroids and was referred for reassessment of his disease status with FDG-PET following 6 weeks of therapy. The FDG-PET images showed remarkable improvement with near total resolution of the FDG hypermetabolism at the initially involved sites. The present case underscores the value of FDG-PET imaging in whole-body monitoring of early response to therapy in patients of sarcoidosis (particularly those with extensive disease) that can be of substantial benefit and indicates the promise of this powerful molecular imaging technique in managing this multisystem disorder.

Early 2'-deoxy-2'-[18F]fluoro-D-glucose PET metabolic response after corticosteroid therapy to differentiate cancer from sarcoidosis and sarcoid-like lesions

PURPOSE

We aimed at investigating whether early metabolic response to corticosteroid therapy may be used as a diagnostic tool to discriminate between cancer and sarcoidosis, a well-known cause of false-positive 2-deoxy-2-[F-18]fluoro-D: -glucose-positron emission tomography (FDG-PET) findings in oncology.

PROCEDURE

Two cancer patients with biopsy-proven sarcoidosis or sarcoid-like reaction had multiple thoracic FDG foci. After infectious disease had been excluded, patients received oral corticosteroids for 16 and 14 days, respectively, and underwent posttherapeutic FDG-PET examination.

RESULTS

Posttreatment PET revealed a complete metabolic response in both patients, and clinical and imaging follow-up showed no sign of cancer progression.

CONCLUSION

Early metabolic response to systemic corticosteroid treatment may be used as a tool in the establishment of final diagnosis when sarcoidosis is suspected in a cancer patient and could be capable of differentiating cancer from sarcoidosis in the case of coexisting diseases.

Functional imaging of inflammatory diseases using nuclear medicine techniques

Molecular imaging with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) is increasingly used to diagnose, characterize, and monitor disease activity in the setting of inflammatory disorders of known and unknown etiology. These disorders include sarcoidosis, atherosclerosis, vasculitis, inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and degenerative joint disease. Gallium-67 ((67)Ga) citrate, labeled leukocytes with technetium-99m ((99m)Tc) or indium-111 ((111)In), and (18)F-fluorodeoxyglucose (FDG) represent the most widely used radiopharmaceutical agents. However, other preparations, such as labeled murine monoclonal antigranulocyte antibodies and labeled human polyclonal nonspecific immunoglobulin G, chemotactic peptides, interleukins, chemokines, and liposomes, have been used to image inflammation. Also, (99m)Tc nanocolloid scintigraphy has been found to be suitable for bone and joint diseases, especially RA. Among the single photon emitting imaging agents, the recommended radiotracer for abdominal inflammation has been (99m)Tc-hexamethylpropylene amine oxime (HMPAO)-labeled leukocytes. During the last several years, FDG-PET imaging has been shown to have great value for the detection of inflammation and has become the centerpiece of such initiatives. This very powerful technique will play an increasingly important role in the management of patients with inflammatory conditions. FDG-PET can provide valuable information in patients with pulmonary and extrapulmonary sarcoidosis, and is a useful tool for testing the efficacy of various treatments. FDG-PET combined with computed tomography holds great promise for assessing atherosclerosis of the large arteries. This modality is very sensitive in detecting large-vessel vasculitis and can be used to monitor the disease course. FDG-PET is also being used to study the inflamed synovial joints both in the experimental and clinical settings, especially for the investigation and management of RA and degenerative joint disease. This technique also has the potential to become the imaging modality of choice in assessing IBD, replacing radiolabeled autologous leukocyte imaging in this setting. Detection of inflammation in the lungs and airways may improve our knowledge about a multitude of disorders that affect these structures. Therefore, functional imaging, led by FDG-PET imaging, is likely to play an increasingly critical role in assessing inflammatory disorders of known and unknown etiologies, and will improve their management immensely in the future.

18F-FDG PET/CT in sarcoidosis management: review and report of 20 cases

PURPOSE

To evaluate the interest of (18)F-fluoro-2-deoxy-D: -glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for diagnosis and therapeutic follow-up of patients with sarcoidosis.

METHODS

Twenty consecutive patients with biopsy-proven sarcoidosis were retrospectively included, in particular, 13 and seven cases of thoracic and extra-thoracic sarcoidosis, respectively. All patients underwent (18)F-FDG PET/CT, and 12 of them also (67)Ga scintigraphy. Five patients were re-examined by (18)F-FDG PET/CT to assess response to corticosteroid (CS) treatment.

RESULTS

Sensitivity of (18)F-FDG PET/CT in detecting active sarcoidosis localizations was determined considering only biopsy-proven sites. For thoracic, sinonasal, and pharyngo-laryngeal localizations, (18)F-FDG PET/CT sensitivity was 100%, 100%, and 80%, respectively. Overall sensitivity for all 36 biopsy-proven localizations improved from 78% to 87% after excluding skin involvement. Considering only the 12 patients who underwent both scintigraphic examinations, overall sensitivity of (67)Ga scintigraphy and (18)F-FDG PET/CT was 58% and 79%, respectively and improved to 67% and 86% after excluding all sites of skin involvement. To evaluate the efficacy of CS treatment, five enrolled patients underwent second (18)F-FDG PET/CT. Complete regression of all foci of pathological tracer uptake was showed in two cases, permitting CS withdrawal after 2 and 6 months. Improvement but incomplete regression of mediastino-pulmonary disease occurred in two patients treated with CS for 19 and 21 months. Disease progression was assessed in one patient treated with decreasing doses of CS during 16 months.

CONCLUSION

(18)F-FDG PET/CT allows to obtain a complete morpho-functional cartography of inflammatory active localizations and to follow treatment efficacy in patients with sarcoidosis, particularly in atypical, complex, and multisystemic forms.

Role of modern imaging techniques for diagnosis of infection in the era of 18F-fluorodeoxyglucose positron emission tomography

During the past several years, it has become quite evident that positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) imaging can play a major role in the management of patients with suspected infection. Particularly, several groups have demonstrated that this powerful imaging methodology is very effective in the evaluation of osteomyelitis, infected prostheses, fever of unknown origin, and AIDS. In view of its extraordinary sensitivity in detecting disease activity and the ability to quantitate the degree of FDG uptake, PET might prove to be an appropriate modality for monitoring disease activity and evaluating response to therapy. FDG-PET has many advantages over existing imaging techniques for the diagnosis of infectious diseases. These include feasibility of securing diagnostic results within 1.5 to 2 h, excellent spatial resolution, and accurate anatomical localization of sites of abnormality. The availability of PET/computed tomography as a practical tool has further enhanced the role of metabolic imaging in many settings. In the future, this modality is very likely to be employed on a routine basis for detecting, characterizing, and monitoring patients with suspected and proven infection.

Critical role of 18F-labeled fluorodeoxyglucose PET in the management of patients with arthroplasty

The most frequent complications after arthroplasty are aseptic loosening and infection. It is often difficult to differentiate aseptic loosening from infection. The management of these two distinct clinical identities is quite different, however. Treatment of aseptic loosening usually requires one-step revision surgery, whereas treatment of infection requires antimicrobial therapy for an extended period before inserting a new prosthesis. Infection associated with arthroplasty is a serious complication and should be treated adequately before proceeding with a surgical intervention. PET with 18F-labeled fluorodeoxyglucose (FDG) has been proposed as an accurate technique for evaluating painful arthroplasty. This review addresses the applications of FDG-PET in such clinical settings. In addition, the potential of PET in the assessing the viability of bone grafts in revision arthroplasty is discussed.

F-18 FDG PET/CT Following Dental Extraction in a Patient With Head and Neck Cancer

A 48-year-old man with squamous-cell carcinoma of the left tonsillar fossa and cervical lymph node metastases was being staged before radiation and chemotherapy. The patient had periodontal disease, and extraction of 2 teeth was performed before therapy. A staging PET/CT was performed 1 week after extraction. This case demonstrates increased FDG uptake at the extraction sites, which could be potentially mistaken for metastatic lesions, especially without the fused PET/CT images.

PET/CT: form and function

Functional imaging with positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of malignant disease, image-guided therapy planning, and treatment monitoring. PET with the labeled glucose analogue fluorine 18 fluorodeoxyglucose (FDG) is a relatively recent addition to the medical technology for imaging of cancer, and FDG PET complements the more conventional anatomic imaging modalities of computed tomography (CT) and magnetic resonance imaging. CT is complementary in the sense that it provides accurate localization of organs and lesions, while PET maps both normal and abnormal tissue function. When combined, the two modalities can help both identify and localize functional abnormalities. Attempts to align CT and PET data sets with fusion software are generally successful in the brain; other areas of the body is more challenging, owing to the increased number of degrees of freedom between the two data sets. These challenges have recently been addressed by the introduction of the combined PET/CT scanner, a hardware-oriented approach to image fusion. With such a device, accurately registered anatomic and functional images can be acquired for each patient in a single scanning session. Currently, over 800 combined PET/CT scanners are installed in medical institutions worldwide, many of them for the diagnosis and staging of malignant disease and increasingly for monitoring of the response to therapy. This review will describe some of the most recent technologic developments in PET/CT instrumentation and the clinical indications for which combined PET/CT has been shown to be more useful than PET and CT performed separately.