Ajit Shinto

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.

177Lu-EDTMP for Treatment of Bone Pain in Patients with Disseminated Skeletal Metastases

177Lu-labeled ethylenediaminetetramethylene phosphonic acid (177Lu-EDTMP) is an agent that concentrates in areas of enhanced osteoblastic activity. The potential of 177Lu-EDTMP for palliation of metastatic bone pain has been documented in the recent literature. The objective of the present work was to study the efficacy and safety of the agent after administration to a limited number of patients. Methods: Ten patients (median age, 68.5 y) with disseminated skeletal metastases received a single bolus infusion of 177Lu-EDTMP (3.7 GBq). All patients had painful bone metastases in more than one anatomic region that were not relieved by narcotic analgesics. The efficacy of the agent was studied by following pain scores assessed at baseline and at 4, 8, and 12 wk after therapy, by using Karnofsky indices and mobility scores, and by determining the requirement for analgesics at baseline and 4 wk after therapy. The toxicity of the agent was assessed by analyzing complete blood counts. Results: A significant reduction in the mean pain score was noted in all patients. The initial mean pain score of 8.44 dropped to 5.73 within 1 mo of treatment. Six patients who required analgesics for pain management had either reduced or completely withdrawn from their use by 4 wk. Compared with initial scans, scans obtained 1 mo after therapy also showed a decreased uptake of the radiotracer. The mobility scores of all patients were higher at 4 wk. The mean Karnofsky performance score of all patients was initially 45 and increased markedly to 69 at 4 wk. None of the patients experienced blood-related toxicity. Conclusion: 177Lu-EDTMP, with only low bone marrow toxicity, provided significant pain relief to patients and considerably increased their mobility, resulting in an overall improvement in the quality of life. The results of the preliminary clinical studies indicate that 177Lu-EDTMP can be considered an effective and safe therapeutic radiopharmaceutical for pain palliation of patients with disseminated skeletal disease.

18F-FDG PET/CT findings in voltage-gated potassium channel limbic encephalitis.

Limbic encephalitis (LE) can be associated with cancer, viral infection, or be idiopathic. One such rare but treatable form is associated with voltage-gated potassium channel (VGKC) antibodies. Typical abnormalities are seen in FDG PET/CT. We report a 39-year-old female patient who presented with 3 months of progressive faciobrachial dystonic seizures and limbic encephalitis. Her serum and cerebrospinal fluid Lgi1 antibody titers were elevated. FDG PET/CT showed basal ganglial hypermetabolism and associated abnormalities. Serial MRI demonstrated atrophic changes predominantly involving the temporal lobes. She is on immunosuppressive therapy and shows clinical improvement with lowering of antibody titers.

Preparation, evaluation, and first clinical use of 177Lu-labeled hydroxyapatite (HA) particles in the treatment of rheumatoid arthritis: utility of cold kits for convenient dose formulation at hospital radiopharmacy

While radiation synovectomy (RSV) constitutes a successful paradigm for the treatment of arthritis, a major cornerstone of its success resides in the selection of appropriate radiolabeled agent. Among the radionuclide used for RSV, the scope of using (177)Lu [T1/2  = 6.65 d, Eβ(max)  = 497 keV, Eγ  = 113 KeV (6.4%), 208 KeV (11%)] seemed to be attractive owing to its suitable decay characteristics, easy availability, and cost-effective production route. The present article describes a formulation of (177)Lu-labeled hydroxyapatite (HA) using ready-to-use kits of HA particles of 1-10 µm size range. The developed kits enable convenient one-step preparation of (177)Lu-HA (400 ± 30 MBq doses) in high radiochemical purity (>99%) and stability at hospital radiopharmacy. The preparation showed promising results in pre-clinical studies carried out in Wistar rats bearing arthritis in knee joints. In preliminary clinical investigation, significant improvement in the disease conditions was reported in 10 patients with rheumatoid arthritis of knee joints treated with 333 ± 46 MBq doses of (177)Lu-HA. The studies reveal that while (177)Lu labeled HA particles holds considerable promise as a cost-effective agent for RSV, the adopted strategy of using HA kits could be a potential step toward wider clinical utilization of radiolanthanide-labeled HA particles.

Theranostic Treatment of Metastatic Bone Pain With 177Lu-DOTMP.

Radiochemical studies and biological evaluation in animal models have shown superior radiochemical properties and better clearance pattern for Lu-DOTMP compared with Lu-EDTMP, an agent recently proven to be efficacious and safe for metastatic bone pain palliation. This prompted us to initiate the clinical evaluation of Lu-DOTMP. The images represent the whole-body scans of a prostate cancer patient (man, 67 years) with skeletal metastases recorded after administering 3.7 GBq (100 mCi) of Lu-DOTMP.

Persistent High Grade Flurodeoxyglucose Uptake in Lipomatous Hypertrophy of the Interatrial Septum on Dual Time Point Imaging and with Ambient Warming

Lipomatous hypertrophy of the interatrial septum (LHIS) is a relatively uncommon disorder of the heart characterized by benign fatty infiltration of the interatrial septum that usually spares the fossa ovalis. LHIS showing flurodeoxyglucose uptake has been reported, and is presumed to be due to activated brown adipose tissue (BAT). We here report a case of a patient who had isolated mediastinal uptake in interatrial septum, mimicking metastasis. Rescanning with external warming to deactivate BAT and a delayed time point image was done, which showed persistent and progressively increasing metabolic uptake respectively, suggesting that LHIS uptake might be unrelated to activated BAT or inflammation.

Faciobrachial dystonic seizures result from fronto–temporo–basalganglial network involvement

Highlights • Faciobrachial dystonic seizures (FBDS) are caused by autoantibodies to leucine-rich glioma-inactivated1 proteins, a component of the voltage-gated potassium channel complex (VGKC-complex) and precede the clinical presentation of limbic encephalitis.• The exact pathophysiology of FBDS is not known and whether they are seizures or movement disorder is still debated.• We suggest the fronto-temporo-basal ganglia network involving the medial frontal and temporal regions along with the corpus striatum and substantia nigra being responsible for the clinical phenomenon of FBDS.• The varied clinical, electrical and imaging features of FBDS in our cases and in the literature are best explained by involvement of this network.• Entrainment from any part of this network will result in similar clinical expression of FBDS, whereas other electro-clinical associations and duration depends on the extent of involvement of the network.

Empiric Therapy with Low-Dose I-131 in Differentiated Cancer Thyroid: What is the Magic Number?

Low dose radioactive iodine-131 (RAI) has been widely reported in the treatment of patients with differentiated thyroid cancer (DTC) since 1970s. However, the clinical outcomes, dosage of I-131 and criteria for successful ablation are different in various studies. The aim of this study was to assess clinical outcome 18-month after RAI therapy in selected DTC patients and identify factors associated with a good response. In this experimental study, among patients with DTC referred to the Nuclear Medicine Department and had an indication for RAI therapy in the period between December 2008 and January 2011, 108 subjects were selected randomly. The patients were randomly divided into three groups and empiric low dose therapy with 30, 50 or 75 mCi of I-131 was administered. Patients were monitored closely clinically and with serum thyroglobulin assays and I-131 whole-body scans at 6 monthly intervals for 18-month after treatment. Among 105 patients who completed follow-up, 86% were successfully ablated with a single low dose of I-131. There was no statistically significant difference in ablation rates in the subgroups receiving 30.50 or 75 mCi of I-131. Cumulative ablation rate was 99% in patients after the second dose of low dose therapy. If appropriate selection criteria are used in DTC, successful remnant ablation can be achieved with low doses of I-131 in the range of 30-75 mCi. No significant differences were found in results achieved with 30.50 or 75 mCi of I-131. As the majority of the DTC patients fall within the inclusion criteria of this study, they can be treated on an ambulatory basis with associated low cost, convenience, and low whole-body radiation-absorbed dose to the patients.