Potential role of FDG PET imaging in predicting metastatic potential and assessment of therapeutic response to neoadjuvant chemotherapy in Ewing sarcoma family of tumors.

AIMS AND OBJECTIVES: The aim of this study was to retrospectively correlate FDG uptake in primary Ewing sarcoma family of tumors (ESFT) with tumor behavior, and to evaluate whether FDG PET can be used to predict response to neoadjuvant chemotherapy (NACT) in this patient group. METHODS: Out of the total 54 patients of recently diagnosed ESFT who underwent pretreatment FDG PET imaging, group I included patients without metastasis at presentation (n = 34) and group II included those with metastasis at presentation (n = 20). Fourteen of these patients had undergone FDG PET after 4 cycles of induction chemotherapy and surgical resection of primary tumor. In this subgroup of 14 patients, maximum standardized uptake value (SUVmax) of primary tumor was estimated before and after 4 cycles of induction chemotherapy and was correlated with the histopathological response in terms of necrosis in the tumor specimen. RESULTS: Mean SUVmax in the primary tumor in group I patients was 6.84 and in group II patients, it was 11.31. The difference between mean SUVmax of these 2 groups was significant by Wilcoxon test analysis, with P < 0.01. In group II patients, SUVmax in metastasis with maximum FDG uptake was consistently lower as compared with that of primary tumor. In subgroup of 14 patients, Pearson correlation analysis showed that percentage change in SUVmax of primary tumor correlated well with percentage necrosis on histopathological examination (P < 0.01). CONCLUSION: FDG uptake in primary ESFT reflected its metastatic potential and hence the aggressive behavior. The significant correlation between change in metabolic activity of the primary tumor and histopathological response after neoadjuvant chemotherapy suggests that FDG PET may be an ideal noninvasive method to assess tumor behavior and response to therapy in ESFT.

Are the effects of cannabis dependence on glucose metabolism similar to schizophrenia? An FDG PET understanding.

BACKGROUND: Cannabis has been associated with transient psychotic states; however, the causal relationship between cannabis and schizophrenia continues to remain a matter of debate. Epidemiological and some biological studies hint at cannabis being an independent risk factor for schizophrenia; this has not been definitively proved. AIMS: We aimed to understand the patterns of glucose uptake in important brain regions among individuals with cannabis dependence and schizophrenia. Furthermore, we compared the interregional metabolic rates in pertinent neural circuits among individuals with cannabis dependence, schizophrenia and normal controls. SETTING AND DESIGN: This is a case-control cross-sectional study that was carried out by a general psychiatry department in collaboration with a nuclear diagnosis unit. MATERIALS AND METHODS: Male volunteers with cannabis dependence, schizophrenia and normal controls underwent FDG PET scanning. Glucose uptakes in pre-selected regions of interest were compared using MANOVA. Finally, Chow tests were used to compare interregional metabolic relationships in the mesocortical and cortical-subcortical-cerebellum circuits. RESULTS: Significant differences (P<0.05) were noted among individuals with cannabis dependence and schizophrenia in the medial and lateral temporal regions. When the neural circuits were compared, significant interregional differences (P<0.05) were noted between individuals with cannabis dependence and normal controls. However, among individuals with cannabis dependence and schizophrenia, no significant differences (P>0.05) were noted in these patterns. CONCLUSIONS: Our findings suggest that cannabis dependence can alter interregional relationships in a manner similar to schizophrenia. This indicates that cannabis could potentially play a role in the development of psychosis by altering neural circuits.

Cannabis dependence: Effects of cannabis consumption on inter-regional cerebral metabolic relationships in an Indian population.

BACKGROUND: The effects of cannabis consumption on neurophysiological function have been a matter of considerable debate. With the legalization of medical marijuana, understanding the consequences of cannabis dependence has become extremely important. AIM: We attempted to understand the influence of cannabis on cerebral glucose metabolism in certain predetermined regions of interest (ROIs). Furthermore, we also explored inter-regional metabolic relationships between ROIs forming the "addiction" and "cognitive dysmetria" circuit. MATERIALS AND METHODS: 2-fluoro, 2-deoxy-glucose positron emission tomography (FDG PET) scans were carried out in 16 male patients (age: 25.3±10.38 years) with cannabis dependence, 8-12 hours after the last cannabis consumption. Resting glucose uptake in 14 pre-determined ROIs was compared with glucose uptake in 16 non-drug using volunteers (age: 29.2±8.39 years). RESULTS: The two groups differed in their lateral and medial temporal glucose uptakes by approximately 16-24%. The relationships between inter-regional glucose uptakes in the two circuits were compared using the Chow Test. Significant differences in inter-regional correlations in the medial temporo-frontal and parieto-thalamic were noted between the two groups. CONCLUSION: The altered metabolic relationships among various brain regions can have potentially important implications for understanding cannabis dependence and cannabis-induced psychopathology.

Micronuclei frequency in peripheral blood lymphocytes of thyroid cancer patients after radioiodine therapy and its relationship with metastasis.

In most cancers peripheral blood lymphocytes exhibit DNA damage. In the case of thyroid cancer the micronucleus (MN) assay has been used to assess DNA damage before and after exposure to iodine-131 ((131)I). The aim of our study was to use this method to assess DNA damage in peripheral blood lymphocytes of thyroid cancer patients and search for its relationship with metastasis as well as (131)I exposure. A significant increase in micronuclei frequency was observed in peripheral blood lymphocytes of 54 thyroid cancer patients in comparison to 38 controls (p=0.000). Further analysis revealed significant elevation in micronuclei index from 48.5 MN/1000 BN cells (range: 25.1-111.2, n=25) in patients without metastasis to 68.1 MN/1000 BN cells (range: 26.2-135.5, n=29, p=0.001) in group of patients with metastasis to one or more sites. There was no clear correlation between the micronuclei frequency and the therapeutic (131)I dose ranging from 0.41 to 31.5 GBq with the exposure interval of <1 to 126 months. In addition, age and sex did not show any influence on micronuclei frequency in either patients or control population. These findings are indicative of increased basal DNA damage in thyroid cancer patients before treatment. Radioiodine treatment did not increase DNA damage measured by the micronuclei frequency for the interval between the last radioiodine dose administered and analysis of blood sample. However a significant increase of peripheral blood lymphocytes micronuclei was observed in thyroid cancer patients with metastasis.

Unsuspected second malignancy detection by FDG PET scan.

A whole body F-18 FDG PET scan was done on a 45-year-old man with a small cell carcinoma of the left lung for a metastatic survey. Imaging showed intense uptake in the left lung (maximum standardized uptake value (SUVmax) of 8.32 corrected for body weight), at the site of the primary and in the hilar lymph nodes. Focal intense uptake was also seen in the rectum (SUVmax of 21.73 corrected for body weight). No anatomic imaging for the pelvis was done, as the patient had no bowel symptoms. Posttreatment PET scan done 9 months after the first scan showed significant reduction in the primary mass in the lung (SUVmax 4.45) but an increase in the rectal mass (SUVmax 83.22). He now complained of bleeding per rectum. Colonoscopy and CT scan of the abdomen showed a mass in the rectum, which on biopsy revealed invasive adenocarcinoma.

Early response assessment in gastrointestinal stromal tumors with FDG PET scan 24 hours after a single dose of imatinib.

Gastrointestinal stromal tumors (GIST), rare mesenchymal tumors of the gastrointestinal tract, are gaining the interest of researchers because of the impressive metabolic response to the targeted molecular therapeutic drug imatinib mesylate. FDG PET is now routinely used to assess treatment response in cases of GIST because this has proven to give metabolic information, which demonstrates response earlier than anatomic imaging modalities. A 50-year-old man presented with abdominal pain and the CT scan showed a large lobulated heterogeneously enhancing mass in the abdomen. Fine needle aspiration cytology (FNAC) confirmed GIST with strong immunoreactivity to C-Kit protein. A baseline FDG PET done before initiation of therapy showed intense nonhomogenous FDG uptake in the mass (standard uptake value maximum, SUVmax of 13.45). A whole body FDG PET, repeated 24 hours after a single dose of imatinib mesylate 400 mg, showed a significant reduction in FDG uptake with a SUVmax of 4.26.

Bronchoalveolar carcinoma of lung masquerading as iodine avid metastasis in a patient with minimally invasive follicular carcinoma of thyroid.

A 52-year-old man with follicular thyroid carcinoma was administered 182 mCi of radioiodine (I-131) a month after total thyroidectomy. Post-therapy scan revealed diffuse uptake of radioiodine in the apical left lung. CT-guided biopsy of this mass revealed mucinous bronchoalveolar carcinoma. Immunohistochemistry for thyroglobulin was negative. An FDG PET scan showed avid uptake in the lung mass. Surgery was ruled out, so he was given chemotherapy, without benefit. The lesion continued to show I-131 uptake even while on daily T3 substitution, suggesting that the mass was thyroid stimulating hormone-independent. Because the mass showed I-131 uptake and chemotherapy was not beneficial, it was decided to treat with I-131. He was continued on T3 substitution therapy and was given 209 mCi of I-131. Follow-up CT scan a few weeks later reported a 1-cm all round reduction of the mass. I-131 scan showed avid tracer uptake in the mass. This case suggests the possibility of this therapeutic option in nonthyroidal tumors that may concentrate radioiodine.

Detection of unsuspected metachronous second primary malignancy giving rise to supposed "non-iodine avid metastasis" in differentiated thyroid carcinoma.

We, herein, explore the added aspect of FDG-PET to investigate an I-131 scan negative for differentiated thyroid carcinomas (DTCs), namely the identification of previously unsuspected second primary malignancies. We present 2 cases of DTC, showing metastatic lesions in the liver and the lungs but showing no I-131 uptake and hence was initially thought to be due to dedifferentiation. FDG-PET was performed as a part of a study to prospectively evaluate its usefulness in "noniodine concentrating metastases" of DTC and to look into the validity of the traditionally described "flip-flop" between I-131 whole-body scan (reflecting the sodium-iodide symporter status in the tumor) and FDG-PET (reflecting the glucose transporter status in the tumor). In addition to the uptake in the metastatic sites, FDG-PET demonstrated unusually intense foci of hypermetabolism in the gut and the right kidney. These were subsequently found to harbor clinically silent coexisting second primary malignancies at those sites giving rise to hepatic and pulmonary metastases. Thus FDG-PET, in both these cases, provided the correct explanation for the absence of radioiodine uptake in the metastatic sites, which were otherwise thought to be due to the loss of differentiation of DTC. This role of FDG-PET in incidentally detecting a coexisting additional primary malignancy giving rise to extensive metastases is relatively unexplored and adds a new dimension to its routine application of a metastatic survey in so-called noniodine avid thyroid carcinoma, which can have a significant bearing on subsequent patient management.

Unusual metastasis of poorly differentiated thyroid carcinoma to the masticator space.

We report an unusual case of metastasis to the masticator space from a poorly differentiated carcinoma of the thyroid. A 34-year-old woman presented with a swelling in the left parotid region of 4 to 5 months' duration, which was progressively increasing in size. A CT scan of the head and neck revealed a heterogeneous, hypervascular mass in the left masticator space. Metastatic disease to the masticator space and to the jaws is a rare event.

Substitution of oral (18)F-FDG for intravenous (18)F-FDG in PET scanning.

UNLABELLED: The aim of this study was to see whether oral administration of (18)F-FDG could be substituted-without significant loss of information-for intravenous injection of (18)F-FDG in patients with difficult intravenous access of any cause, such as that often seen in cancer patients after many cycles of chemotherapy. METHODS: PET after both oral and intravenous administration of (18)F-FDG was performed on 2 healthy volunteers and 7 patients. An interval of 48 h was maintained between the oral administration and the intravenous administration. All scans were visually analyzed. Semiquantitative analysis of specific areas was done by calculating standardized uptake values (SUVs). Scanning was performed 60 min after intravenous tracer administration and 90 min after oral tracer administration. RESULTS: All lesions seen after intravenous administration were visualized on the oral study as well. SUVs were lower on the oral study than on the intravenous study. CONCLUSION: Oral (18)F-FDG can successfully be substituted for intravenous (18)F-FDG in patients with difficult intravenous access. However, because of the large amount of (18)F-FDG retained in the gut, careful interpretation will be required when disease of the gastrointestinal tract is being evaluated.

F-18 FDG PET scan findings in a case of carcinoma of the breast with a rare site of metastases to the gingival region.

Malignant tumors of the breast have an inherent potential to metastasize more often to the regional lymph nodes. It is rare to find a metastasis to the oral region from a primary in the breast, but when this does occur, it usually involves the jawbones rather than the soft tissues. A 33-year-old premenopausal woman, a diagnosed case of locally advanced right breast carcinoma, underwent right modified radical mastectomy followed by chemotherapy as per the institutional protocol. She presented after 2 years with an exophytic growth in the upper alveolar region of the oral cavity. Biopsy indicated gingival metastasis from a poorly differentiated adenocarcinoma of the breast. She was referred for F-18 FDG PET scan to evaluate the disease status before planning radiotherapy to the gingival metastasis. F-18 FDG PET scan was done after intravenous injection of 370 MBq (10 mCi) of tracer. Whole-body PET images were reconstructed in iterative algorithm (OSEM). Whole-body F-18 FDG PET scan showed hypermetabolic foci in the midmaxillary region (SUV max: 6.5), upper end of the right humerus, a large hypermetabolic area in the upper zone of the right lung with contiguous hilar node involvement on the right side of the lung, and an area of intense hypermetabolic activity in the left acetabular and ischial region. The present case demonstrates a rare site of metastasis in the oral region from carcinoma of the breast.