Enhanced detectability of recurrent brain tumor using glucose-loading F-18 FDG PET

A 43-year-old man with a history of lung cancer, brain metastasis, and gamma knife radiosurgery underwent FDG PET/CT to differentiate recurrence from radiation necrosis. Basal PET/CT scan showed equivocal uptake in the margin of necrotic tumor. After glucose loading (10% glucose 50 mL for 5 minutes), marginal FDG uptake was more easily depicted. Proton magnetic resonance spectroscopy (1H-MRS) showed increased Cho/Cr ratio (1.7), which was consistent with tumor recurrence. The patient underwent whole brain radiotherapy thereafter. It is implicated that hyperglycemia-induced reduction of glucose uptake in recurrent brain tumors was less than in a normal brain, resulting in higher tumor-to-gray matter ratio.     

Differentiation between carcinoid and sarcoid with F-18 FDG PET and In-111 pentetreotide

A patient who presented with weight loss and recurrent left lower lobe pneumonia was diagnosed with endobronchial carcinoid. Chest CT scan demonstrated extensive mediastinal and hilar lymphadenopathy suggesting stage IIIB disease, but radionuclide imaging with In-111 pentetreotide and F-18 FDG PET diagnosed 2 distinct pathologic processes based on functional differences between neuroendocrine tumors (expressing somatostatin receptors) and sarcoidosis (intensely FDG-avid). The possible association of carcinoid with sarcoidosis and sarcoid-like reactions in regional lymph nodes should always be considered, and the staging process should include both anatomic and functional imaging and biopsy confirmation of suspected metastatic lesions.     

Myelofibrosis on F-18 FDG PET Imaging

A 60-year-old male was referred for a positron emission tomography (PET) scan using F-18 fluoro-2-deoxyglucose (F-18 FDG) for evaluation of a right lung opacity identified on a computed tomography (CT) scan. The patient also had a history of idiopathic myelofibrosis. The PET scan revealed markedly increased uptake throughout the spleen and liver, which were massively enlarged. There was also significantly increased uptake diffusely throughout the bone marrow. These findings are a reflection of the patient's myelofibrosis.     

F-18 FDG PET demonstration of sclerosing mesenteritis

Sclerosing mesenteritis is a rare, combined inflammatory and fibrotic process of unknown etiology. Detailed cross-sectional imaging of this entity has been reported with computed tomography. The author presents an additional case of sclerosing mesenteritis demonstrated on fluorine-18 fluorodeoxyglucose positron emission tomography with multidetector computed tomographic correlation.     

A case of three synchronous primary tumors demonstrated by F-18 FDG PET

We present an F-18 FDG PET scan which demonstrates 3 synchronous primary malignancies. The patient is a 61-year-old man who presented with weight loss and dysphagia. He was initially diagnosed with squamous cell carcinoma of the midesophagus, and was then found to have an adenocarcinoma in the right lung. A staging PET scan additionally showed increased left tonsillar uptake. Subsequent biopsy confirmed squamous cell carcinoma of the left tonsil. The demonstration of 3 synchronous primaries by PET is probably rare.     

F-18 FDG PET in detecting uterine leiomyoma

PURPOSE: Uterine leiomyoma, benign tumors of the human uterus, are clinically apparent in about 25% of women and the most common solid pelvic tumors. The purpose of this study was to investigate the F-18 2-fluoro-2-deoxy-D-glucose (FDG) uptake in the uterine leiomyoma and assess the correlation between the intensity of FDG uptake in the uterine leiomyomas and menstrual cycle. METHODS: A total of 589 charts of healthy females examined by whole body FDG positron emission tomography (PET) for health screening examination were reviewed retrospectively. Twenty-two of them were suspected gynacecological tumors and referred to the department of gynacecology to ascertain the nature of the causes. Final diagnosis as uterine leiomyomas were made based on uterine sonography, pelvic computed tomography, or pelvic magnetic resonance imaging scans. We defined FDG uptake as Grade I when FDG uptake was less than liver uptake, Grade II when FDG uptake was equal to liver uptake, and Grade III when FDG uptake was greater than liver uptake. The menstrual cycle was recorded on the day of performing FDG PET in premenopausal women. RESULTS: The FDG uptake in the uterine region is Grade I in three of these 22 females (13.65%), Grade II in 16 (72.7%), and Grade III in 3 (13.65%). CONCLUSION: There is no significant correlation between the intensity of FDG uptake in the uterine leiomyomas and menstrual cycle (P=.914).     

F-18 FDG PET in insular thyroid cancer

PURPOSE: Insular thyroid cancer (ITC) is known to be a rare subtype of follicular thyroid carcinoma showing poor differentiation and an unfavorable prognosis. The authors evaluated the use of F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) for restaging and follow-up in ITC. METHODS: Five patients (2 male, 3 female) with elevated thyroglobulin levels (mean, 86 ng/mL; range 1.3-180 ng/mL) during follow-up underwent FDG PET (Siemens ECAT Exact 47). PET results were correlated to histopathologic and radiologic findings as well as to the results of whole-body radioiodine scintigraphy. In 1 patient a series of 4 PET scans was done. RESULTS: FDG PET showed a total of 10 tumor sites, at least 1 in each patient. Four of those lesions were detected by computed tomography (CT) as well, which in addition revealed 3 lesions that had normal glucose consumption. Five PET lesions were missed by the CT scan because they were found outside the examined volume of CT. Only 1 PET-positive lesion was also radioiodine positive. Three radioiodine-positive lesions with normal glucose metabolism were detected. CONCLUSION: As known for well and poorly differentiated thyroid cancer of the follicular epithelium, ITC may also show discordance between radioiodine studies and FDG-positive lesions. Given their initially poor differentiation, the ITC clearly showed the expected dominance of less well-differentiated, FDG-positive lesions. Therefore, FDG PET seems to be a very useful tool for the staging and restaging of such tumors.     

F-18 FDG PET Findings for Vogt-Koyanagi-Harada Disease

Vogt-Koyanagi-Harada disease is a rare multisystemic granulomatous autoimmune disorder affecting pigmented tissues such as the choroid, meninges, inner ear, and the skin. Neurologic symptoms are usually mild. Clinical manifestations include generalized muscle weakness, headache, meningismus, vertigo, decreased visual acuity, hearing loss and mental changes ranging from mild confusion to psychosis, hemiparesis, dysarthria, and aphasia. Seizures are very rare. We describe a case of ¹⁸F-fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) and software-fused PET-magnetic resonance imaging (MRI) in Vogt-Koyanagi-Harada disease with seizure.     

F-18 FDG PET/CT imaging of solitary genital tuberculosis mimicking recurrent lymphoma

A 65-year-old man who had multiple lymph nodes swelling was pathologically diagnosed with diffuse large B cell lymphoma. After initiation of induction chemotherapy, F-18 FDG PET/CT showed a significantly decreased extent of previous lymphomatous lesions except for 2 newly developed focal hypermetabolic lesions in the prostate and left epididymis. The specimens from the prostate and orchiectomy revealed tuberculosis lesions. After a 3-month antituberculosis regimen, there was definitively decreased glucose uptake in the prostate on F-18 FDG PET. F-18 FDG PET may be helpful for characterizing genitourinary tuberculosis and monitoring antituberculosis treatment.