Ajit Kumar Padhy

[18F] FDG PET/CT in patients with fever of unknown origin: a local experience.

Objective2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography ([18F] FDG PET/CT) has become an established imaging tool in oncology and is now emerging in the field of infectious disease. The aim of this study is to assess the value of fluorine [18F] FDG PET/CT in the investigation of patients with fever of unknown origin (FUO). Methods[18F] FDG PET/CT scans and clinical data of 12 patients were reviewed. These patients met the revised definition criteria of FUO (febrile illness of greater than 3 weeks duration, temperature greater than 38.3°C and no diagnosis after at least 3 days of in-patient investigation or 2 weeks of outpatient investigation). A retrospective analysis of our local database was performed and evaluated for the diagnostic contribution of [18F] FDG PET/CT scans. ResultsAn infective cause of the FUO was found in four (33.3%) patients, a neoplasm in two (16.7%) patients, non-infectious inflammatory disease or autoimmune in one (8.3%) patient. A definitive causative agent could not be found in five (41.7%) patients despite extensive investigations.In all, five (41.6%) patients had a PET/CT scan that was abnormal and was deemed ‘helpful’ as part of the investigation that pointed to the final diagnosis. Two (16.7%) patients had abnormal scans, which were deemed ‘not-helpful’ for the final diagnosis. Conclusion[18F] FDG PET/CT can be helpful in some patients with FUO. This study adds value to the limited data published so far on this subject.

Fluorine-18-fluorodeoxyglucose PET/CT for the evaluation of suspected recurrent uterine leiomyosarcomas

Background Uterine leiomyosarcomas are rare and aggressive malignancies of the uterine corpus with high recurrence rates and poor prognoses. The current recommendation for detection of recurrent uterine leiomyosarcoma involves periodic physical examination and conventional imaging such as CT or MRI. The role of fluorine-18-fluorodeoxyglucose positron emission tomography with integrated computed tomography (FDG-PET/CT) in the detection of recurrent uterine leiomyosarcomas is not yet established. Purpose To evaluate the use of FDG-PET/CT as a single integrated modality for the evaluation of suspected recurrent uterine leiomyosarcomas. Material and Methods A retrospective study was performed on patients who underwent FDG-PET/CT scans for suspected recurrent uterine leiomyosarcoma. Only patients with follow-up data were included in the study. FDG-PET/CT was evaluated as a single integrated imaging modality. A positive lesion on FDG-PET/CT was defined as a focal abnormality detected on either the PET or CT components, or both. Results Sixteen consecutive patients over 5 years underwent FDG-PET/CT for suspected recurrent uterine leiomyosarcoma. Five patients were excluded due to incomplete follow-up data. The remaining 11 patients were aged 36–58 years (mean age 48). FDG-PET/CT had a sensitivity of 100% (95% CI 63–100) and specificity of 100% (95% CI 20–100) for the detection of recurrent uterine leiomyosarcomas. Sites of metastases include lungs, peritoneum, liver, pancreas and breast, of which lungs and peritoneum were the most common. Two (18%) patients had discordant findings: FDG-PET negative metastatic nodules in the breast and lung detected on the CT component. The maximum standardized uptake value (SUVmax) of metastatic lesions ranged from 2.0 to 16.0 (mean 7.6). Conclusion FDG-PET/CT as a single integrated modality may be a useful for the evaluation of suspected recurrent uterine leiomyosarcomas. FDG-PET negative discordant nodules detected on the CT component may represent metastases and should be followed up closely.

Clinical features of differentiated thyroid carcinoma in children and adolescents from a sub-Himalayan iodine-deficient endemic zone.

Northern India is an identified sub-Himalayan iodine-deficient endemic zone. We retrospectively analysed the case files of children with differentiated thyroid carcinoma from this endemic zone and attempted to define the disease in terms of its presentation, clinical course and outcome of radioiodine therapy. Between 1967 and June 2000, 1135 patients with thyroid cancer were treated in our centre and 80 (7%) were less than 20 years of age. There were 45 females and 35 males. Histologically, 85% of patients had papillary carcinoma and the rest follicular carcinoma. Cervical lymph node involvement was seen in 66% of patients, and distant metastasis, mainly pulmonary, in 29%. In children less than 10 years of age, 75% of patients had distant metastasis at the time of presentation. The post-surgery 48 h radioiodine neck uptake was 12.2±9.6%. Ninety-six per cent of the residual thyroid, 90% of nodal metastases and 57% of pulmonary metastases were ablated. Although nine patients had nodal recurrence between surgery and radioiodine treatment, no recurrence was observed thereafter, and three disease-related deaths (all in children less than 10 years of age) were seen in the mean follow-up of 6 years. We conclude that, except for the relatively higher incidence of follicular thyroid cancer and the higher mortality in the less than 10 year age group, the course and outcome of differentiated thyroid carcinoma in children from iodine-deficient areas is no different from that in children in iodine-sufficient areas.

Insular carcinoma of thyroid : a subset of anaplastic thyroid malignancy with a less aggressive clinical course

Insular carcinoma of the thyroid appears to represent an entity situated morphologically and biologically in an intermediate position between the well-differentiated and undifferentiated (anaplastic) tumors. The retention of I-131 concentrating ability by this variant, unlike anaplastic, is very encouraging and amenable to detection and therapy by radioiodine after initial aggressive surgery. A 46-year-old man with a histologic label of anaplastic thyroid carcinoma has had an unusually prolonged disease-free survival and histopathologic review confirmed insular carcinoma. Postoperative radioiodine evaluation revealed avid concentration of tracer in the thyroid bed. Thus, it is possible to ablate with radioiodine. The insular carcinoma should be considered as a distinct clinicopathologic entity and widespread awareness of this variant of tumor may help pathologists, surgeons, and nuclear medicine practitioners to aggressively treat the condition after initial diagnosis.

Dosimetric Considerations in Radioimmunotherapy and Systemic Radionuclide Therapies: A Review

Radiopharmaceutical therapy, once touted as the “magic bullet” in radiation oncology, is increasingly being used in the treatment of a variety of malignancies; albeit in later disease stages. With ever-increasing public and medical awareness of radiation effects, radiation dosimetry is becoming more important. Dosimetry allows administration of the maximum tolerated radiation dose to the tumor/organ to be treated but limiting radiation to critical organs. Traditional tumor dosimetry involved acquiring pretherapy planar scans and plasma estimates with a diagnostic dose of intended radiopharmaceuticals. New advancements in single photon emission computed tomography and positron emission tomography systems allow semi-quantitative measurements of radiation dosimetry thus allowing treatments tailored to each individual patient.

Spontaneous perforation of the common bile duct in infancy: role of Tc-99m mebrofenin hepatobiliary imaging.

A 2-month-old infant had jaundice that began 3 days after birth. The clinical features were suggestive of biliary obstruction. Tc-99m mebrofenin hepatobiliary imaging confirmed the diagnosis of spontaneous perforation of the common bile duct, and surgical intervention resulted in progressive recovery.

Planar Tc99m--sestamibi scintimammography should be considered cautiously in the axillary evaluation of breast cancer protocols: results of an international multicenter trial.

BackgroundLymph node status is the most important prognostic indicator in breast cancer in recently diagnosed primary lesion. As a part of an interregional protocol using scintimammography with Tc99m compounds, the value of planar Tc99m sestamibi scanning for axillary lymph node evaluation is presented. Since there is a wide range of reported values, a standardized protocol of planar imaging was performed.MethodsOne hundred and forty-nine female patients were included prospectively from different regions. Their mean age was 55.1 ± 11.9 years. Histological report was obtained from 2.987 excised lymph nodes from 150 axillas. An early planar chest image was obtained at 10 min in all patients and a delayed one in 95 patients, all images performed with 740–925 MBq dose of Tc99m sestamibi. Blind lecture of all axillary regions was interpreted by 2 independent observers considering any well defined focal area of increased uptake as an involved axilla. Diagnostic values, 95% confidence intervals [CI] and also likelihood ratios (LR) were calculated.ResultsNode histology demonstrated tumor involvement in 546 out of 2987 lymph nodes. Sestamibi was positive in 30 axillas (25 true-positive) and negative in 120 (only 55 true-negative). The sensitivity corresponded to 27.8% [CI = 18.9–38.2] and specificity to 91.7% [81.6–97.2]. The positive and negative LR were 3.33 and 0.79, respectively. There was no difference between early and delayed images. Sensitivity was higher in patients with palpable lesions.ConclusionThis work confirmed that non tomographic Tc99m sestamibi scintimammography had a very low detection rate for axillary lymph node involvement and it should not be applied for clinical assessment of breast cancer.

A Report on the Implementation Aspects of the International Atomic Energy Agency’s First Doctoral Coordinated Research Project, “Management of Liver Cancer Using Radionuclide Methods With Special Emphasis on Trans-Arterial Radio-Conjugate Therapy and Internal Dosimetry”

Liver cancer is one of the most dreaded cancers, and it is highly prevalent in the developing countries, where the resources are extremely scarce to deal with this disease using the current commercially available and expensive therapeutic radiopharmaceuticals. The International Atomic Energy Agency (IAEA), in pursuit of its mandate to promote the application of nuclear technology in the health care in its Member States, has developed and clinically evaluated a new and cost-effective therapeutic radio-conjugate, rhenium-188 ((188)Re)-lipiodol for the treatment of hepatocellular carcinoma through its first Doctoral Coordinated Research Project. The ready availability of no-carrier-added (188)Re from the tungsten-188/(188)Re generator represents a potentially important source of a therapeutic radioisotope for a broad range of therapeutic applications in nuclear medicine. The alumina-based tungsten-188/(188)Re generator system comes with reasonable cost and exhibits attractive therapeutic properties, excellent performance and very long useful shelf-life. Because of the long shelf-life of several months, the use of this generator offers a unique opportunity for the cost-effective and routine availability of a versatile therapeutic radioisotope on an on-demand basis. Further, using its extensive global network and outreach, the IAEA has also transferred the technology of the in-house preparation and use of (188)Re-labeled lipiodol to many institutions around the world, which can now prepare (188)Re-labeled lipiodol in their own radiopharmacy laboratories and treat patients. This effort of the IAEA in trying to address some of the challenges of liver cancer therapy in developing countries has been and truly a global venture with involvement and contributions from several organizations, institutions and numerous individuals. This article discusses some of the implementation aspects of this very important activity of the Agency.

Thyroid Incidentalomas on Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography: Incidence, Malignancy Risk, and Comparison of Standardized Uptake Values

Introduction To determine the incidence of fluorine-18-fluorodeoxyglucose (FDG) avid thyroid incidentalomas detected on positron emission tomography (PET) with integrated computed tomography (CT), and correlate the FDG–PET-CT findings to cytology. Methods A total of 942 FDG–PET-CT reports were retrospectively reviewed. Patients with FDG-avid thyroid incidentalomas were further reviewed for correlative cytology. Results The incidence of FDG-avid thyroid incidentalomas is 2.2%. Thyroid malignancies were identified in 3 of 6 patients who underwent cytologic correlation, with a positive predictive value of 50% (95% confidence interval, 14%-86%). The mean maximum standardized uptake values of benign and malignant FDG-avid thyroid incidentalomas were 5.6 and 6.6, respectively. Conclusion A FDG-avid thyroid incidentaloma may predict underlying malignancy. Cytologic assessment should be considered for FDG-avid thyroid incidentalomas.

Pancreatic metastasis detected by F-18 FDG PET/CT in a patient with breast cancer.

Pancreatic involvement by metastasis from other primaries is rare and accounts for approximately 2% to 4% of pancreatic tumors. In this article, we describe FDG-avid pancreatic involvement in a patient with diagnosis of breast cancer. We conclude that FDG PET can be a convenient noninvasive method of early detection of recurrence and in monitoring metastatic disease during follow-up in such patients. A positive FDG PET warrants histopathologic correlation for appropriate treatment.