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BACKGROUND: We sought to determine the utility of PET-MRI in diagnosing Idiopathic Inflammatory Myositis (IIM), and look for association between FDG uptake and clinical, pathological and laboratory parameters. METHODS: A retrospective, observational study was conducted on IIM patients having positive serum autoantibodies and who underwent PET-MRI (3-Tesla SIEMENS Biograph MR scanner) between 2017 and 2021. Thirty patients who underwent PET-MRI to detect systemic metastasis without muscle involvement formed the control group. RESULTS: In the IIM cohort, female: male sex ratio was 1.73, mean age at diagnosis was 40.33 years, and the mean duration of illness was 7 months. 33.33% of patients had severe limb weakness. Mi2B (43.33%), Mi2A (43.33%), PL-7(10%), PL-12(6.67%), SRP (16.67%), Tif1gamma (3.33%), NxP2 (3.33%), Ro-52(40%), PM-Scl, U1-RNP, ANA (26.67%) were the serum autoantibodies identified. Using SUV max Ratio to quantify FDG uptake, PET-MRI showed a sensitivity of 100% with 93.3% specificity in diagnosing IIM.FDG uptake was maximum in proximal lower limb region followed by proximal upper limb. Multivariate regression analysis showed that the severity of muscle weakness, serum Mi2B antibody positivity and serum creatinine kinase levels had a significant positive correlation with FDG uptake (value of 0.005, 0.043, 0.042, respectively for whole-body FDG uptake). FDG uptake also showed good correlation with histopathological features and muscle MRI, but there was no significant association with treatment response. Three female patients in our cohort had primary malignancy involving the breast, uterus, and cervix. CONCLUSIONS: PET-MRI is a promising diagnostic modality for IIM. PET-MRI reflects the severity of muscle inflammation, showing good association with various clinical/laboratory parameters, histopathology, and muscle MRI. Parameters associated with severe muscle inflammation in PET-MRI-clinical severity of muscle weakness, Mi2B positivity, and serum creatine kinase levels-may be used as clinical/laboratory markers of disease severity in IIM. PET-MRI has the added advantage of detection of systemic malignancy.
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PURPOSE: The aim of this study is to compare the diagnostic accuracy of amino acid PET, MR perfusion and diffusion as stand-alone modalities and in combination in identifying recurrence in post-treatment gliomas and to qualitatively assess spatial concordance between the three modalities using simultaneous PET-MR acquisition. METHODS: A retrospective review of 48 cases of post-treatment gliomas who underwent simultaneous PET-MRI using C11 methionine as radiotracer was performed. MR perfusion and diffusion sequences were acquired during the PET study. The following parameters were obtained: TBRmax, TBRmean, SUVmax, and SUVmean from the PET images; rCBV from perfusion; and ADCmean and ADCratio from the diffusion images. The final diagnosis was based on clinical/imaging follow-up and histopathology when available. ROC curve analysis in combination with logistic regression analysis was used to compare the diagnostic performance. Spatial concordance between modalities was graded as 0, 1, and 2 representing discordance, < 50% and > 50% concordance respectively. RESULTS: There were 35 cases of recurrence and 13 cases of post-treatment changes without recurrence. The highest area under curve (AUC) was obtained for TBRmax followed by rCBV and ADCratio. The AUC increased significantly with a combination of rCBV and TBRmax. Amino acid PET showed the highest diagnostic accuracy and maximum agreement with the final diagnosis. There was discordance between ADC and PET in 22.9%, between rCBV and PET in 16.7% and between PET and contrast enhancement in 14.6% cases. CONCLUSION: Amino acid PET had the highest diagnostic accuracy in identifying recurrence in post-treatment gliomas. Combination of PET with MRI further increased the AUC thus improving the diagnostic performance.
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Primary hyperparathyroidism is caused by parathyroid adenomas in 85% of the cases. Since parathyroid adenomas are known for their ectopic location, presurgical localization of the suspected site of adenoma is desirable. However, current imaging modalities are not always successful in localizing ectopic parathyroid adenomas. The aim of this case report is to show that (11)C-methionine positron emission tomography could accurately localize ectopic parathyroid adenomas in patients in whom conventional imaging had failed or is inconclusive.
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Positron emission tomography/computed tomography (PET/CT) using 2-deoxy-2-(fluorine-18) fluoro-D-glucose ((18)F-FDG) has become a standard diagnostic modality in oncological practice. F18-FDG PET/CT is sensitive in detecting malignancy; however, specificity is low in differentiating infections or inflammatory diseases from tumor. In the present case study, we report a patient with postoperative carcinoma of tongue presenting with cervical lymphadenopathy and fever. The PET/CT scan showed metabolically active generalized lymphadenopathy, and a possibility of lymphoma was suggested. Fine needle aspiration cytology showed the Ziehl-Neelsen staining to be strongly positive for acid-fast bacilli and first line of antitubercular drug was administrated. Six months later after the initiation of therapy, a follow-up PET/CT showed remarkable improvement of the disease status. This case study illustrates that tubercular infection can be a pitfall in F18-FDG PET/CT imaging. PET positive lesions do not always indicate malignancy, and histological confirmation of lesions with biopsy should always be performed. Once diagnosed to be tubercular, FDG PET/CT is a powerful imaging tool in monitoring the therapy.
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INTRODUCTION: A photon-deficient ('cold') vertebra on fluorine-18 fluorodeoxyglucose (F-FDG) PET is a known entity and can arise as a result of varying etiologies. A proper interpretation of this observation is required to make an accurate diagnosis for appropriate management. METHODS: Twelve cases with 'cold' vertebrae on F-FDG PET/computed tomography (CT) were selected and analyzed from a population of 600 patients with a known malignancy who had undergone whole-body F-FDG PET/CT for staging, disease viability assessment, response to treatment, or suspected recurrence purposes. The patterns were studied and correlated with clinical history and the results of the low-dose CT performed with the PET scan for attenuation correction and anatomical localization. RESULTS: The most common cause for cold vertebrae was found to be postexternal radiotherapy, causing photopenia involving multiple vertebrae corresponding to the radiotherapy portals. Two other causes found in the study were the destruction of the vertebral marrow cavity by metastatic tumor cells and vertebral hemangioma. Characteristic features of 'cold' vertebrae have been described in the study with illustrations. CONCLUSION: Pattern recognition coupled with clinical history and CT correlation of 'cold' vertebrae on F-FDG PET/CT can help in diagnosing the correct underlying etiology, which can help in better management of the patients.
