Nawab S. Baghel

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.

Early documentation of therapeutic response at 6 weeks following corticosteroid therapy in extensive sarcoidosis: promise of FDG-PET.

A 52-year-old man, who was treated with antitubercular drugs for 1 year without any benefit for an initial diagnosis of tuberculosis, and was referred for further evaluation. An FDG-PET study was performed to evaluate the whole-body disease status, which showed multiple abnormal foci in bilateral neck nodes, mediastinal, axillary, and multiple abdominal (para-aortic and inguinal) nodes, and the liver, spleen, and thyroid. A rebiopsy of the inguinal nodes for a definitive diagnosis was confirmatory of sarcoidosis. He had a history of hypothyroidism, which is a frequent accompaniment of sarcoidosis due to the association of autoimmunity in this population. He was treated with oral corticosteroids and was referred for reassessment of his disease status with FDG-PET following 6 weeks of therapy. The FDG-PET images showed remarkable improvement with near total resolution of the FDG hypermetabolism at the initially involved sites. The present case underscores the value of FDG-PET imaging in whole-body monitoring of early response to therapy in patients of sarcoidosis (particularly those with extensive disease) that can be of substantial benefit and indicates the promise of this powerful molecular imaging technique in managing this multisystem disorder.

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.

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.

Regional brain metabolism in schizophrenia: An FDG-PET study.

Background: Recent technological advances have established beyond any doubt the biological nature of schizophrenia. Functional neuroimaging using FDG-PET forms an important technique in understanding the biological underpinnings of psychopathology of schizophrenia. Methods: Eighteen male patients diagnosed as having schizophrenia and having active psychosis as determined by PANSS were subjected to FDG-PET scanning under resting conditions. The glucose uptake in selected regions of interest was studied across the spectrum of schizophrenia. Results: Chronicity and severity of illness did not influence cerebral glucose metabolism. Participants with negative schizophrenia had significantly decreased metabolism in all regions of the brain as compared to the positive type. The positive syndrome of schizophrenia was associated with significantly increased glucose metabolism in the medial temporal regions, basal ganglia and left thalamic regions. Hypometabolism was also noted in the cerebellum. Conclusion: While a number of brain areas can be identified as potential causative regions and hypotheses regarding putative mechanisms can be formed, the considerable heterogeneity of schizophrenia poses a great challenge in the precise delineation of the disease process.

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.

FDG PET in ruptured pulmonary hydatid cyst: assessing disease extent and tracking the path of drainage.

A 13-year-old female hailing from a remote village presented with a history of intermittent fever, cough, and expectoration along with multiple episodes of hemoptysis. She was treated for tuberculosis without benefit before was she presented to us. Ultrasonography of the chest was suggestive of a loculated pleural effusion. Computed tomography (CT) scan of the chest revealed a loculated cyst in the left lung lingula and the tapping of the cyst demonstrated transudative fluid. The serum IgG titer for Echinococcus granulosus was raised (1:320). F-18 fluorodeoxyglucose-positron emission tomography (FDG PET) imaging was considered to ascertain the extent of disease involvement and tracking the path of drainage, based upon its potential useful role in assessing infection and inflammation that has been emphasized in the recent literature. The scan showed uptake in the wall of the cyst as well as a linear uptake along a track that was directed anteroinferiorly corresponding to the drainage track of the ruptured pulmonary hydatid cyst. This was in addition to the low grade tracer uptake in both sided hilar and mediastinal regions.

Regional brain metabolism in schizophrenia: The influence of antipsychotics

BACKGROUND Schizophrenia has been associated with a plethora of metabolic changes in the brain that vary with duration and type of psychoses. Additionally, it has been observed that antipsychotics can further alter cerebral glucose metabolism. These changes resulting from antipsychotics have been postulated to be reflective of the duration and mechanism of action of the medication. AIMS We aimed to examine the influence of antipsychotics on brain metabolism in individuals with schizophrenia in a naturalistic setting. SETTINGS AND DESIGN A cross-sectional study was carried out by the psychiatry department of a tertiary care hospital in collaboration with the Radiation Medicine Centre. MATERIALS AND METHODS Eighteen male patients with schizophrenia in different phases of treatment underwent an 18F-deoxyglucose positron emission tomography scan in a resting state 12 hours after the last dose of antipsychotic. STATISTICAL ANALYSIS The types and duration of treatment were then compared with the regional glucose uptake in 14 predetermined regions of interest. The relative Uptake Values were further compared using SPSS 11.0. RESULTS An immediate increase followed by a decrease in cortical uptake was noted while the basal ganglia uptake remained high, albeit with a decreasing trend. Typical antipsychotics were associated with lower frontal cortical and higher basal ganglia and cerebellar uptake as compared to atypical antipsychotics. CONCLUSION The differential influence of the type and duration of antipsychotic on glucose uptake suggests a possible trend towards long-term side effects with typical medications that were not noted on clinical examination. This however needs to be confirmed with larger, controlled studies.

Response to low-dose oral capecitabine monotherapy in an elderly frail patient with metastatic breast carcinoma and impaired renal function: documentation by fluorodeoxyglucose positron emission tomography

The effi cacy of chemotherapy with drugs used alone (monotherapy) or in sequence (serial single-agent therapy) has been recently highlighted in the literature with the viewpoint of being both safe and better tolerated and hence applicable to elderly patients with poor health status and who are intolerant to cytotoxic chemotherapy. In a case vignette, we describe the clinical value of fl uorodeoxyglucose positron emission tomography (FDGPET) imaging for monitoring and documenting a response to a novel approach. It involves using the better-tolerated capecitabine monotherapy in an elderly, frail female patient with metastatic breast carcinoma who demonstrated progressive disease 5 years after a modifi ed radical mastectomy. She could not be administered other cytotoxic complex chemotherapy regimens because of her poor health status and impaired renal function. The patient was a 78-year-old woman with a referral diagnosis of infi ltrating ductal carcinoma of the right breast. The baseline FDG-PET demonstrated large-volume metastatic disease in the liver, abdominal nodes, and mediastinum, the left chest and lung, the right arm subcutaneous tissue, and the left femur trochanteric region (Fig. 1). She was administered low-dose oral capecitabine (500 mg/m/day), a fl uoropyrimidine carbamate with antineoplastic activity, for three cycles before a repeat FDG-PET study. The second series of FDG-PET scans (Fig. 2) demonstrated a signifi cant reduction in the overall disease burden, particularly in the liver and abdomen. The foci in the subcutaneous tissue of the right arm and in the left femur trochanteric region were no longer visualized. The FDG-PET studies were acquired following standard protocol: The patient fasted for at least 6 h before the injection. At 60 min after intravenous injection of 444 MBq FDG, the scan was undertaken using a whole-body single-ring dedicated bismuth germinate (BGO) detector crystal-based GE Advance PET scanner (General Electric Medical Systems, Milwaukee, WI, USA). Images were reconstructed using the attenuation weighted Ordered Subsets Expectation Maximization (OSEM) algorithm. Novel therapeutics are being continuously explored in oncology and by functional imaging, with FDG-PET playing a pivotal role. The obvious benefi t of early documentation of a therapeutic response with FDG-PET imaging makes this the modality of choice for monitoring disease activity when a patient is being treated with Received: September 13, 2010 / Accepted: November 3, 2010

Meckel scan findings in an infant with ileocolic intussusception.

A 7-month-old male infant who presented with bleeding per rectum was evaluated and diagnosed to have ileocolic intussusception on ultrasonography. Despite ultrasonography-guided saline reduction, there was persistence of bleeding per rectum. He was given blood transfusion and referred for Tc-99m pertechnetate scan to rule out ectopic gastric mucosa. The scan was done as per the standard institution protocol and the images revealed a focus of progressively increasing tracer uptake in the right lower abdominal quadrant suggesting the presence of ectopic gastric mucosa. An exploratory laparotomy revealed ileocolic intussusception secondary to Meckel diverticulum acting as a pathologic lead point (PLP). A wedge resection of the intestinal wall containing the diverticulum with suture closure was performed. The presence of Meckel diverticulum and ectopic gastric mucosa was confirmed on subsequent histopathological examination of the specimen. The patient rapidly improved postoperatively and was discharged 9 days after surgery. Bleeding per rectum can be seen in both intussusception and in Meckel diverticulum with ectopic gastric mucosa. Intussusception originating from a Meckel diverticulum as PLP remains a diagnostic challenge because of the overlapping symptoms.The Meckel scan findings, in this case, avoided the further CT scan, angiography, and endoscopy for the diagnosis of the cause of symptoms, sparing not only the time but cost of investigations and unnecessary radiation exposure to the patient.