Role of fluorodeoxyglucose positron emission tomography in the diagnosis of neurosarcoidosis

Advancements in Positron Emission Tomography/Magnetic Resonance Imaging and Applications to Diagnostic Challenges in Neuroradiology

Since the clinical adoption of magnetic resonance (MR) in medical imaging, MR has proven to be a workhorse in diagnostic neuroradiology, with the ability to provide superb anatomic detail as well as additional functional and physiologic data, depending on the techniques utilized. Positron emission tomography/computed tomography has also shown irreplaceable diagnostic value in certain disease processes of the central nervous system by providing molecular and metabolic information through the development of numerous disease-specific PET tracers, many of which can be utilized as a diagnostic technique in and of themselves or can provide a valuable adjunct to information derived from MR. Despite these advances, many challenges still remain in neuroradiology, particularly in malignancy, neurodegenerative disease, epilepsy, and cerebrovascular disease. Through improvements in attenuation correction, motion correction, and PET detectors, combining the 2 modalities of PET and MR through simultaneous imaging has proven feasible and allows for improved spatial and temporal resolution without compromising either of the 2 individual modalities. The complementary information offered by both technologies has provided increased diagnostic accuracy in both research and many clinical applications in neuroradiology.

Distinguishing neurosarcoidosis from multiple sclerosis based on CSF analysis: A retrospective study

OBJECTIVE

To characterize a cohort of patients with neurosarcoidosis with particular focus on CSF analysis and to investigate whether CSF values could help in distinguishing it from multiple sclerosis (MS).

METHODS

This retrospective cohort study enrolled 85 patients with a diagnosis of neurosarcoidosis (possible, probable, or definite). CSF total protein, white cell count, and angiotensin-converting enzyme levels were measured. CSF and serum oligoclonal immunoglobulin G (IgG) patterns were analyzed with the use of odds ratios and binary logistic regression.

RESULTS

Eighty patients had a probable (nonneural positive histology) or definite (neural positive histology) diagnosis of neurosarcoidosis. Most frequent findings on MRI were leptomeningeal enhancement (35%) and white matter and spinal cord involvement (30% and 23%). PET scan showed avid areas in 74% of cases. CSF analysis frequently showed lymphocytosis (63%) and elevated protein (62%), but CSF-selective oligoclonal bands were rare (3%). Serum ACE levels were elevated in 51% of patients but in only 14% of those with isolated neurosarcoidosis. Elevated CSF ACE was not found in any patient.

CONCLUSIONS

Large elevations in total protein, white cell count, and serum ACE occur in neurosarcoidosis but are rare in MS. The diagnostic use of these tests is, however, limited because minimal changes may occur in both. MS clinical mimics in neurosarcoidosis are not common, and intrathecal synthesis of oligoclonal IgG is a powerful discriminator because it is rare in neurosarcoidosis but occurs in 95% to 98% cases of MS. We suggest caution in making a diagnosis of neurosarcoidosis when intrathecal oligoclonal IgG synthesis is found.

Biomarkers of Metabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the deterioration of motor neurons. However, this complex disease extends beyond the boundaries of the central nervous system, with metabolic alterations being observed at the systemic and cellular level. While the number of studies that assess the role and impact of metabolic perturbations in ALS is rapidly increasing, the use of metabolism biomarkers in ALS remains largely underinvestigated. In this review, we discuss current and potential metabolism biomarkers in the context of ALS. Of those for which data does exist, there is limited insight provided by individual markers, with specificity for disease, and lack of reproducibility and efficacy in informing prognosis being the largest drawbacks. However, given the array of metabolic markers available, the potential exists for a panel of metabolism biomarkers, which may complement other current biomarkers (including neurophysiology, imaging, as well as CSF, blood and urine markers) to overturn these limitations and give rise to new diagnostic and prognostic indicators.

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.

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.

FDG PET imaging in sarcoidosis

The objective of this review is to highlight the clinical utility of FDG-PET/CT for evaluation of patients with chronic sarcoidosis. The emphasis was on the potential advantages and disadvantages of this technique in these patients based on which recommendations were made. The advantage of FDG-PET/CT technique is that it can visualize FDG accumulation in activated inflammatory cells and simultaneously provide PET and CT images. Of particular interest is the use of FDG-PET/CT for the staging and identification of occult sites and sites suitable for biopsy and for the assessment of inflammatory active sarcoidosis in patients with prolonged symptoms, especially when other markers of the disease are within normal values. FDG-PET/CT also provides a better visualization of extrathoracic sites of active sarcoidosis, such as in the bones, liver, spleen, and retroperitoneal lymph nodes. The use of FDG-PET/CT is of special interest in cardiac sarcoidosis because this potentially life-threatening disease is sometimes present in asymptomatic patients. FDG-PET/CT also has a role in the clinical management of patients with chronic persistent sarcoidosis, such as for planning treatment, monitoring response, and long-term follow-up. The limitations of FDG-PET/CT in patients with sarcoidosis are discussed in the context of a "sarcoidosis-lymphoma syndrome" and potentially excessive radiation exposure. Further prospective multicentre studies are needed to refine the clinical applications of FDG-PET/CT in patients with sarcoidosis and drive the field forward.

Granulomatous lesions in bone marrow: clinicopathologic findings and significance in a study of 48 cases

PURPOSE

Granulomas in bone marrow are an infrequent finding related to various disorders. The aim of this study was to review our clinical experience with granulomatous bone marrow disease and to describe the contributions of recent diagnostic tools, such as (18)F-Fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) and molecular biology.

METHODS

Clinical, laboratory and morphological data on patients with a granuloma based on bone marrow biopsy analysed in the University Hospital Lyon from May 2004 to July 2010 were reviewed.

RESULTS

We identified 57 cases among 9641 bone marrow biopsies, representing an incidence of 0.59% in the series and an annual incidence of 9.5 cases per year. Nine biopsies performed for staging a known pathology were excluded from further analysis. Among the 48 remaining patients, associated disease was demonstrated in 79%, with infections being the most common (33%), following by sarcoidosis (21%), malignancy (19%) and therapy-induced granulomas (6%). One previously unpublished entity is described: infection with Bartonella henselae diagnosed using molecular biology from node and skin biopsies in two renal transplant patients. (18)F-FDG-PET, performed in 13 cases, showed hypermetabolic foci consistent with sarcoidosis in two cases. Positive PCR result for an infectious pathogen was obtained in three bone marrow samples (Mycobacterium tuberculosis, n=1; Mycobacterium genavense, n=2).

CONCLUSION

In comparison to previous research, our study reports high proportions of cases caused by sarcoidosis and unknown causes. (18)F-FDG-PET could show signs consistent with sarcoidosis and molecular biology is useful for the detection of fastidious bacteria in immunocompromised patients.

Isolated spinal neurosarcoidosis: An enigmatic intramedullary spinal cord pathology-case report and review of the literature

Isolated spinal cord neurosarcoidosis (NS) in the absence of systemic disease or intracranial involvement is exceptionally rare. Adjunctive laboratory tests though useful may not be reliable and the absence of any pathognomonic radiological features makes the diagnosis difficult. As spinal cord NS may be a presenting feature of systemic sarcoidosis which may be occult on routine workup, (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) may be of value in unraveling this systemic involvement avoiding biopsying the spinal cord. A case of truly isolated NS is described with review of literature on this enigmatic pathology. Long segment intramedullary signal changes with focal parenchymal along with dural/meningeal enhancement in the absence of significant cervical stenosis in a young patient of northern European or African-American decent is very suggestive of NS and although may be presumably treated with steroids; there should be a low threshold for spinal cord biopsy especially in the absence of response to steroids to confirm isolated spinal cord NS in a patient with clinical neurological deterioration.

Clinical value of 2-deoxy-[18F]fluoro-d-glucose positron emission tomography in patients with cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is one of the most common spinal cord disorders in the elderly. It is usually diagnosed by MRI, but in a significant number of patients the clinical course of CSM does not correlate with the extent of the spinal cord compression. Recent studies have suggested that a distinct metabolic pattern of the cervical cord, as assessed by PET with 2-deoxy-[18F]fluoro-d-glucose (18F-FDG) may predict a patient's clinical outcome after decompressive surgery for cervical spine stenosis. The authors provide an overview of the recent literature regarding the value of PET with 18F-FDG of the cervical cord in patients with CSM, paying attention to prognostic aspects and the potential role of inflammatory processes in the acute phase of the disease.

Spinal magnetic resonance imaging manifestations at neurological onset in Japanese patients with spinal cord sarcoidosis

OBJECTIVE

We retrospectively investigated spinal magnetic resonance imaging (MRI) manifestations at neurological onset in Japanese patients with spinal cord sarcoidosis.

METHODS

Between July 2000 and April 2012, we reviewed our database and recruited patients with spinal cord sarcoidosis. On spinal MRI performed at neurological onset, the following items were evaluated: the vertebral-segment distribution and length of intramedullay T2-elongated lesions, abnormal enhancement patterns and distributions and the concomitant presence of spondylosis and associated extraspinal lesions. If available, brain MRI scans were concomitantly assessed.

RESULTS

Nine patients were enrolled (four men and five women; median, 49 years). Reflecting Japanese epidemiological backgrounds, a predilection for occurrence was observed in young men and middle-aged women. Intramedullary T2-elongated lesions were present in eight patients, peaking at the C5 level, with a mean length of 3.7 ± 2.6 vertebral segments. Spondylosis coexisted in the middle-aged patients. Abnormal intramedullary enhancement with concomitantly involved the nerve roots was observed in six patients, comprised of two types reflecting the disease progression: linear- and/or nodular enhancement along the surface of the spinal cord and intramedullary enhancement consisting of patchy, broad-based enhancement adjacent to the cord surface. Five patients had associated extraspinal lesions, including lymphadenopathy in four patients and brain involvement in four patients.

CONCLUSION

Spinal cord sarcoidosis exhibits a predilection for young men and middle-aged women among Japanese individuals and is characterized by intramedullary T2-elongated lesions spreading more than three vertebral segments peaking at the C5 level, two types of abnormal intramedullary enhancement reflecting disease progression, frequent nerve root involvement and lymphadenopathy.

Neurosarcoidosis: guidance for the general neurologist

Neurosarcoidosis (NS) more commonly occurs in the setting of systemic disease. The diagnosis is based on a clinical history suggestive of NS, presence of noncaseating granulomas, and supportive evidence of sarcoid pathology, laboratory, and imaging studies. NS could involve any part of the nervous system and often demands high doses of steroids for symptom control. It presents low response to isolated steroids administration and frequently requires immunosuppressive agents. In NS, lymphocytes are polarized toward an excessive Th1 response, leading to overproduction of TNF-alpha and INF-gama, as well as lL-2 and IL-15. Infliximab, a chimeric monoclonal antibody that neutralizes the biological activity of TNF-alpha, is a new option in the NS treatment. We revised pathophysiology, clinical manifestations, diagnostic work up, and treatment of NS as guidance for the general neurologist.

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.

Bilateral Vestibular Hypofunction in Neurosarcoidosis: A Case Report

We describe the case of a 59-year-old woman who presented with progressive bilateral vestibidar hypofunction and who was found to have bilateral granulomatous mass lesions of the mesial temporal lobe. Initially, her condition stabilized neurologically with corticosteroids, but a diagnosis of neurosarcoidosis was delayed because of the unusual presentation and persistently normal chest imaging results and serum angiotensin-converting enzyme (ACE) levels. Approximately 1 year after her initial presentation, the patient died of complications of a myocardial infarction and pulmonary embolism. Sarcoidosis should be considered in the differential diagnosis of idiopathic bilateral vestibular hypofunction even if the chest imaging and serum ACE levels are normal, particularly when there is evidence of a multisystem process.

Multi-technique imaging of sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder of unknown aetiology. The diagnosis is suggested on the basis of wide ranging clinical and radiological manifestations, and is supported by the histological demonstration of non-caseating granulomas in affected tissues. This review highlights the multisystem radiological features of the disease across a variety of imaging methods including multidetector computed tomography (CT), magnetic resonance imaging (MRI) as well as functional radionuclide techniques, particularly 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT). It is important for the radiologist to be aware of the varied radiological manifestations of sarcoidosis in order to recognize and suggest the diagnosis in the appropriate clinical setting.

[Granulomatous interstitial nephritis: A retrospective study of 44 cases]

PURPOSE

Granulomatous interstitial nephritis (GIN) are identified in 0.5 to 1,3% of all renal biopsies. Renal outcome and treatment modalities are not clearly established in the literature.

METHODS

We retrospectively analyzed a case series of 44 GIN identified among all renal biopsies performed between 1984 and 2005 in the Rhône-Alpes area.

RESULTS

The study population included 25 men and 19 women with a mean age of 56 years, and mean diagnostic delay was 11 months. Renal function was severely impaired (mean creatinine clearance 24mL/min). Proteinuria was observed in 77% (mean value 0,9 g/24h) of the patients and associated with microscopic hematuria and leukocyturia in 30% and 25%, respectively. The most common diagnosis was sarcoidosis (25%, n = 11), followed by drug-induced GIN (9%, n = 4), tuberculosis (6,8%, n=3), hemopathy-related paraneoplastic GIN (6,8%, n = 3), HIV infection (n = 1) and chronic renal allograft rejection (n = 1). In other patients, no aetiology was found (48%, n = 21). Severity of renal failure justified hemodialysis in 34% (n = 15) of the patients. Three patients underwent renal transplantation. Nonetheless, renal outcome was generally favorable: renal function improved in 41% (n = 18) and stabilized in 34% (n = 15) of patients.

CONCLUSIONS

Sarcoidosis, drug-induced and infections represent the main causes of GIN. Histologic features are not specific enough to determine the aetiology. Corticosteroids is the gold standard in sarcoidosis, drug-induced, and idiopathic GIN. Treatment is etiologic in the other cases.

Isolated bilateral trigeminal neuropathy in sarcoidosis presenting with neurotrophic corneal ulcers

Sarcoidosis is a multisystem granulomatous disease that may affect various organs. Nevertheless, involvement of the trigeminal nerve is exceedingly uncommon. This report presents a rare case of isolated bilateral trigeminal neuropathy presenting with neurotrophic corneal ulcers. The patient was treated with topical chloramphenicol and lubricants, as well as botulinum toxin injection to the upper eyelid to induce ptosis. Our case illustrates the importance of recognizing that bilateral corneal ulceration might be a manifestation of sarcoidosis. Physicians should be aware of this rare association, when treating sarcoidosis patients with eye related symptoms.

Fluorodeoxyglucose positron emission tomography (FDG-PET) is useful in the diagnosis of neurosarcoidosis

A 45-year-old man presented with a progressive transverse spinal cord syndrome. MRI scanning revealed bitemporal and multiple spinal lesions with significant enhancement after gadolinium administration mimicking an acute disseminated encephalomyelitis. CSF analyses showed a lymphocytic pleocytosis. After treatment with high dose steroids clinical improvement was observed with a secondary decline shortly thereafter. MRI rescanning showed no remarkable alterations of the lesions. Further diagnostic work-up included a fluorodeoxyglucose positron emission tomography (FDG-PET) of the whole body to search for occult inflammation or neoplasia. The FDG-PET showed hypermetabolic foci corresponding to the lesions on MRI and additionally increased uptake in mediastinal and pulmonary hilar lymph nodes. A mediastinal lymph node was biopsied. Pathology was consistent with the diagnosis of sarcoidosis. The usual diagnostical tools to evaluate a sarcoidosis, such as serum angiotensin converting enzyme (ACE) and computed tomography of the chest were performed initially and revealed no pathological results. Therefore, in this case FDG-PET was crucial for the diagnostic work-up leading to an accessible inflammatory lesion outside the CNS for biopsy and the final diagnosis of sarcoidosis.

Neurosarcoidosis

Although neurosarcoidosis seems to occur in only 5% to 10% of patients who have sarcoidosis, it may lead to significant complications. The diagnosis of neurosarcoidosis usually relies on indirect information from imaging and spinal fluid examination. Although MR imaging remains the most sensitive technique for detecting neurologic disease, other tests, including positron emission tomography scanning and cerebral spinal fluid examination, can provide important information. The role of immunosuppressive agents such as methotrexate, cyclophosphamide, and azathioprine has been expanded, and these agents should be considered for the treatment of some manifestations of neurosarcoidosis. Reports of the antitumor necrosis factor agent infliximab suggest that this drug can be helpful for patients who have neurosarcoidosis.

Apport de la tomographie par émission de positons pour le diagnostic de sarcoïdose au cours d'une myopathie granulomateuse

INTRODUCTION

Granulomatous myositis is a rare condition that has been described in association with sarcoidosis. In the absence of sarcoidosis or other underlying disease, a diagnosis of isolated granulomatous myositis is considered.

OBSERVATION

A 61-year-old African man presented with progressive limitation in running and proximal atrophy of the lower limbs for the past year. Quadricipital muscle biopsy revealed non-caseating epithelioid granulomas and multinuclear giant cells. Whole body fluorodeoxyglucose positron emission tomography ((18)FDG-PET) revealed hypermetabolic activity of salivary and lachrymal glands, and mild hypermetabolism in the mediastinal lymph nodes. Minor salivary gland biopsy was consistent with sarcoidosis.

CONCLUSION

To our knowledge, this is the first reported case of sarcoid myopathy demonstrating the diagnostic usefulness of (18)FDG-PET.

[Positron emission tomography in internal medicine]

FDG-PET is now an established diagnostic tool in oncology. Fluorodeoxyglucose is not a specific tracer for malignant lesions but rather for elevated glucose metabolism, present not only in cancer but also in inflammatory and infectious lesions. FDG-PET has thus been suggested for diagnosis of fevers of unknown origin, deep bone or visceral infectious foci, inflammatory vasculitis or sarcoidosis and unknown primary tumors, all frequent situation in internal medicine. The main characteristics of FDG-PET are its ability to rule out focal inflammation or infection with a high degree of certainty when the examination is negative because of its good negative predictive value and its usefulness as an early marker of therapeutic response, compared with anatomy-based or conventional scintigraphic imaging. Large-scale prospective studies are necessary, however, before FDG-PET is integrated into routine clinical use. It should be compared with different techniques already validated (biology, radiology, conventional scintigraphic imaging) and its cost-effectiveness should be evaluated.

Impact of [18F]-fluorodeoxyglucose ([18F]-FDG) imaging in sarcoidosis: unsuspected neurosarcoidosis discovered by [18F]-FDG PET and early metabolic response to corticosteroid therapy

A 46-year-old woman, with biopsy proven pulmonary sarcoidosis, was referred for an [18F]-FDG PET/CT scan that depicted multivisceral involvement and an unusual [18F]-FDG focus located in the pituitary fossa consistent with pituitary sarcoidosis. This was confirmed by decreased antidiuretic hormone blood levels and contrast-enhanced CT scan. This unsuspected neurosarcoidosis prompted corticosteroid therapy. A [18F]-FDG-PET/CT examination performed 10 weeks after initiation of treatment revealed complete recovery. It is suggested that the skull base should be included in the PET scanning of patients with sarcoidosis. [18F]-FDG imaging may be useful in the early evaluation of response to treatment.

La tomographie d'émission de positons en médecine interne : applications actuelles et perspectives d'avenir

PURPOSE

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a promising imaging technique that has already proven effective in modifying patient care in oncology. Fluorodeoxyglucose still remains the main radiopharmaceutical agent routinely used for PET imaging. A growing interest has recently lead to broaden PET research on benign disorders. The field of inflammatory or immune diseases and globally the field of internal medicine could also be impacted by FDG-PET.

MAIN POINTS

Great vessels vasculitides and fever of unknown origin have both been studied by several teams and could become indications for PET. In addition, current indications now extend to paraneoplastic syndromes. It is thus possible to foresee that the clinical applications for PET will continue to expand in these patients.

PERSPECTIVES AND PROJECTS

In the future, inflammatory arthritis, chronic inflammatory bowel diseases, systemic erythematous lupus, histiocytosis, or pulmonary and retroperitoneal fibrosis might benefit from PET even if, available data remains scarce to this day. Although PET will probably alter the landscape of patient management in internal medicine in the near future, additional clinical research is still needed to ascertain the exact role of PET.

Apport de la consultation interniste dans le diagnostic étiologique des uvéites. Étude comparative portant sur 66 patients

BACKGROUND

After exclusion of a masquerade syndrome, uveitis may be associated with infection, systemic diseases, specific ocular diseases, or may be drug-induced. In order to improve diagnostic strategy in uveitis, we performed a comparative study to assess the importance of internist and ophtalmologist's collaboration and we proposed a well-adapted diagnostic procedure.

MATERIAL AND METHODS

A comparative study was performed in a tertiary centre. The population was divided in two groups. The first one was retrospective and consisted of patients treated at the Ophthalmology department of Croix Rousse Hospital from 1991 to 2002 without internist's collaboration. The second one was prospective and consisted of patients referred in the same centre in 2003 and 2004 with intervention of an internist. Patients of less than 18 years of age with pre-existent diagnosis, specific ocular diseases, toxoplasmosis infection, or with human immunodeficiency virus infection were excluded.

RESULTS

Sixty-six patients were included. Anterior uveitis was the most frequent form (25 cases), followed by panuveitis (20 cases), posterior uveitis (14) and intermediate uveitis (7). The most frequent cause of uveitis was systemic disease (19 cases) followed by infection (7 cases) and neurological entities (4 cases). The rate of diagnosis was 30.3% without internist's intervention and 60.6% when patients were referred to an internist (P=0,01). The internist intervention was contributive in 75% of diagnoses.

CONCLUSIONS

The internist intervention significantly enhances the rate of etiological diagnoses in uveitis. These results should further strengthen the internist/ophthalmologist collaboration for patients with uveitis.

Combined C-11 Methionine and F-18 FDG PET Imaging in a Case of Neurosarcoidosis

PURPOSE

PET scanning of the brain with F-18 FDG and C-11 methionine (MET) is useful for characterizing brain lesions discovered at MRI or CT. Most positive PET scans indicate malignancy. However, this case report demonstrates positive F-18 FDG and C-11 MET PET scans in a patient with a nonmalignant condition, neurosarcoidosis.

MATERIALS AND METHODS

We detail the history and evaluation of a 59-year-old woman who presented with ataxia. The patient's evaluation included a contrast-enhanced MRI followed by PET scanning of the brain with C-11 MET and of the brain and trunk with F-18 FDG. The patient subsequently underwent biopsy of a lesion as directed by MRI and PET.

RESULTS

The MRI demonstrated multiple enhancing leptomeningeal lesions consistent with metastatic disease. PET with F-18 FDG and C-11 MET demonstrated lesions in both cerebellar hemispheres with F-18 FDG accumulation in the mediastinum and left hilum. Biopsy of a brain lesion directed by MRI and PET revealed sarcoidosis.

CONCLUSIONS

In evaluating brain lesions, PET with F-18 FDG and C-11 MET can help localize the lesion best suited for biopsy. However, not all lesions that have increased uptake on C-11 MET or F-18 FDG PET are malignant. Granulomatous inflammatory diseases such as neurosarcoidosis should also be considered in the differential diagnosis.