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Abhinav Jaimini,
Madhavi Tripathi,
Maria M D'Souza,
Puja Panwar,
Rajnish Sharma,
Saloni Mehta, Santosh Pandey,
Sanjiv Saw,
Dinesh Singh,
Yachna Solanki,
Anil K Mishra,
Anupam Mondal
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ABSTRACT: AIM: The striatal-to-occipital ratio (SOR) is commonly used as an analytical parameter in L-3,4-dihydroxy-6-F-fluorophenylalanine (FDOPA) PET studies. It has been shown to be useful in differentiating idiopathic Parkinson's disease (IPD) patients from healthy individuals. We assessed the performance of SORs and subregional ratio of striatal-to-occipital ratios (RSORs) in the clinical assessment of nigrostriatal dopaminergic function for differentiating typical IPD from atypical parkinsonian disorders (APD). MATERIALS AND METHODS: A total of 117 patients referred from movement disorder clinics in speciality neurology centres underwent an FDOPA PET study and were kept under follow-up for at least 2 years. Sixty-five patients (43 IPD and 22 APD) completed the 2-year follow-up and were included in the final analysis. Their PET images were spatially normalized to occipital counts and analysed with three striatal subregional regions of interest (caudate, anterior putamen and posterior putamen) and two occipital regions of interest. The RSORs of the caudate and posterior putamen, the caudate and anterior putamen, the caudate and whole putamen and the anterior putamen and posterior putamen were also calculated and compared between the IPD and APD groups using the t-test. RESULTS: The P values for these SORs were found to be insignificant between IPD and APD patients (caudate: 0.1325; anterior putamem: 0.5469; and posterior putamen: 0.9835). However, the RSORs of the caudate and posterior putamen showed significant differences between these two populations of patients. CONCLUSION: The SOR method is already known to be a good diagnostic tool to differentiate between IPD patients and the normal population. SOR, however, fails to distinguish IPD from APD patients, and hence the RSOR of the caudate and posterior putamen can be utilized to differentiate between them.
Nuclear Medicine Communications 02/2013; · 1.40 Impact Factor
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ABSTRACT: Anaplastic thyroid carcinoma is an uncommon, highly aggressive malignancy usually presenting in the elderly. An eighteen year old boy was recently diagnosed as anaplastic carcinoma of the thyroid. PET/CECT scan performed for staging, revealed a large FDG avid heterogeneously enhancing thyroid mass with bilateral jugular venous thrombosis, which also showed increased FDG uptake, thus pointing towards tumor thrombus. To our knowledge, this is the first case wherein the PET/CT diagnosis of tumor thrombosis from anaplastic thyroid carcinoma was made in a young patient.
07/2012;
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ABSTRACT: 18F-fluorodeoxyglucose (18F-FDG) has limited specificity in the evaluation of intracranial lesions as it is taken up by inflammatory and granulomatous lesions as well. 11C-methionine is known to have a higher specificity in tumor detection, delineation, and differentiation of benign from malignant lesions. However, its uptake in granulomatous lesions remains unclarified.
The aim of this study was to explore the value of 11C-methionine PET/CT and 18F-FDG in the evaluation of intracranial tuberculomas.
11C-methionine PET/CT followed by 18F-FDG PET/CT study was performed on 12 patients with intracranial tuberculomas. The diagnosis was confirmed for all cases on histopathological evaluation and/or follow-up. Quantitative analysis was performed for all cases by measuring the lesion-to-normal gray matter uptake ratio.
A high lesion-to-normal gray matter uptake ratio was observed on both 11C-methionine (1.8 ± 0.38) and 18F-FDG scans (1.64 ± 0.26) in all newly diagnosed cases. Lesion detection and delineation was superior on 11C-methionine PET/CT. In addition, 11C-methionine appeared to be a more sensitive indicator for assessing early therapeutic response and incomplete therapeutic response in intracranial tuberculomas. There was complete concordance in the number and sites of lesions detected on 11C-methionine PET/CT and radiological imaging modalities (namely, CT and MRI).
This preliminary study suggests that in newly diagnosed, untreated intracranial tuberculomas, 11C-methionine, like 18F-FDG, may have limited specificity in distinguishing it from a neoplastic lesion. However, it may play an important role in assessing the response to antitubercular treatment. Further studies are warranted to explore the potential of 11C-methionine in this regard.
Nuclear Medicine Communications 04/2012; 33(4):408-14. · 1.40 Impact Factor
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Madhavi Tripathi,
Rajnish Sharma,
Raunak Varshney,
Abhinav Jaimini,
Jyotika Jain,
Maria M D Souza,
Jaspriya Bal, Santosh Pandey,
Nitin Kumar,
Anil K Mishra,
Anupam Mondal
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ABSTRACT: With the availability of multiple positron emission tomography (PET) tracers for neurooncology, there is a need to define the appropriate tracer in a given clinical setting, and it is in this regard that we undertook this study to directly compare F-18 flurodeoxyglucose (FDG) PET and C-11 methionine (MET) PET for the evaluation of recurrence in primary brain tumors.
Thirty-seven patients with a history of treated primary brain tumors referred for evaluation of recurrent disease were initially included in the study. Two patients had to be excluded because of insufficient follow-up. There were 23 males and 12 females, mean age: 33.7 ± 16.4 years; range: 5 to 65 years. All patients underwent the MET and FDG study on the same day. Visual image interpretation was performed independently by 2 PET physicians for each tracer using the plain PET and fused PET/CT images; the FDG images were evaluated first. Images were analyzed semiquantitatively using tumor to normal contralateral cortex ratios (T/N). Each patient was followed up for a minimum of 18 months. Imaging results were compared with histopathology on tumor excision or biopsy in 14 patients and with clinical follow-up and MRI/MRS at the end of 18 months in 21 patients.
The final diagnosis was tumor recurrence in 24 patients and no recurrence/stable disease in 11 patients. On FDG, findings in 15/35 (42%) were suggestive of recurrent tumors. On MET, findings in 24/34 (70.5%) cases were suggestive of recurrent tumors. Spatially separated secondary lesions including intraventricular deposits were clearly delineated in 5 cases, 3 were glioblastoma multiforme (GBM) and 2 were anaplastic astrocytomas. One of the secondary lesions was missed on FDG PET. Using a cutoff for T/N ratio on FDG of >0.75 to differentiate recurrence from no recurrence, sensitivity of FDG was 81.2% (confidence interval [CI] = 54.4%-96%), whereas specificity was 88.9% (CI = 51.8%-99.7%). Area under the curve was 0.819 (CI = 0.615-0.943), P = 0.0003. Using a cutoff for T/N ratio of >1.9 to differentiate recurrence from no recurrence, sensitivity of MET was 94.7% (CI = 74.0%-99.9%), whereas specificity was 88.89% (CI = 51.8%-99.7%). Area under the curve was 0.942 (CI = 0.785-0.995), P < 0.0001. Interobserver agreement, κ coefficient, for MET was 0.93, suggesting good interobserver agreement, whereas for FDG, it was fair (0.23).
MET should be the radiotracer of choice in the evaluation of recurrence of primary brain tumors because the sensitivity for detection and delineation of the possible recurrent tumor, as well as secondary deposits, is higher with MET. MET-PET is an easier technique to interpret, irrespective of the glioma grade, with less interobserver variability and straightforward localization of tumorous accumulation.
Clinical nuclear medicine 02/2012; 37(2):158-63. · 3.92 Impact Factor
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Rajnish Sharma,
Madhavi Tripathi,
Maria M D'Souza,
Abhinav Jaimini,
Raunak Varshney,
Puja Panwar,
Aruna Kaushik,
Sanjeev Saw,
Romana Seher, Santosh Pandey,
Dinesh Singh,
Yachna Solanki,
Anil K Mishra,
Anupam Mondal,
Rp Tripathi
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ABSTRACT: A variety of neurodegenerative disorders produce significant abnormal brain function which can be detected using fluorodeoxyglucose positron emission tomography (FDG PET) scan even when structural changes are not detected on CT or MRI Scan. A study was undertaken at our institute to evaluate the FDG PET/CT findings in Indian population suffering from mild cognitive impairment (MCI), Alzheimer's disease (AD), fronto-temporal dementia (FTD), dementia with lewy body disease (DLBD) and other miscellaneous causes of dementia.
117 subjects having neurocognitive deficits and 36 normals were included in our study. All patients underwent a detailed history and clinical examination. This was followed by a mini mental state examination. Subsequently an FDG brain PET scan and an MRI were done.
In the patient population included in our study group 36 were normal, 39 had MCI, 40 had AD, 14 had FTD, and 13 had DLBD and 11 dementia due to other miscellaneous causes. MCI patients showed primarily reduced tracer uptake in the mesio-temporal cortex. AD patients showed reduced tracer concentration in temporo-parietal lobes, while patients with advanced diseases showed frontal lobe disease additionally. In subjects of FTD, reduced radiotracer uptake in the fronto-temporal lobes was noted. In addition, FTD patients also showed basal ganglia defects. In contrast the DLBD patients showed globally reduced FDG uptake including severely affecting the occipital cortices.
In the current study the F18-FDG PET scans have been shown to be highly useful in the diagnosis of various neurocognitive disorders of the brain. AD was found to be the most common dementia in the Indian population followed by MCI. Diffuse Lewy body disease, FTD and other miscellaneous categories of dementia had a near similar incidence.
Indian Journal of Nuclear Medicine 04/2011; 26(2):67-77.
