Evaluation of focal thyroid lesions incidentally detected in fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography images.

Background and Purpose: Increased uptake in the thyroid gland (TG) is often identified as an incidental finding on the whole body fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) in non-thyroid cancer patients. Currently, there is no consensus on the appropriate approach for the management of these cases. Thyroid ultrasound, scintigraphy and fine-needle aspiration biopsy (FNAB) are suggested to exclude malignant thyroid lesions. Our aim is to determine the importance of increased F-18-FDG uptake in the TG on positron emission tomography/computed tomography (PET/CT) scans in patients who are being screened for various forms of non-thyroid cancer. Materials and Methods: We evaluated 2000 cases undergoing whole body PET/CT scanning between April 2011 and October 2012. The age, sex, type of primary cancer, maximum standardized uptake value (SUV max ), size of the thyroid nodules and cervical lymph nodes (CLNs) on 18 F-FDG PET/CT images and if available, the biopsy results were evaluated. Results: In total, 57 patients (23 men, 34 women, mean age ± standard deviation (SD), 60.89 ± 14 years) showed an increased fluorine-18-fluorodeoxyglucose ( 18 F-FDG) uptake by the TG (average SUV max : 4.07 ± 3.7). The CLNs were detected in 19/57 patients (33%). Only 20 cases (35%) received FNAB. The final histopathological diagnosis was papillary thyroid carcinoma in seven patients (mean SUV max ± SD: 6.0 ± 5.43) and benign thyroid disease in seven patients (mean SUV max ± SD: 2.36 ± 0.63). The FNAB results were undetermined for six patients. Conclusion: Focal high 18 F-FDG uptake in the TG may be associated with an increased risk of malignancy, but the clinical significance is unclear. More data are needed to elucidate the role of the SUV in the differentiation of benign and malign thyroid lesions. If a focal increase in 18 F-FDG uptake in the TG on PET/CT is present, a prompt histopathological evaluation should be suggested to clinicians for definitive diagnosis.

Role of 18F-fluorodeoxy glucose PET-CT in asymptomatic epithelial ovarian cancer with rising serum CA-125: A pilot study.

Background. We evaluated the role of 18F-fluorodeoxy glucose (FDG) PET-CT scan in the diagnosis of early relapse in patients with epithelial ovarian cancer (EOC) who were asymptomatic but had a rising serum CA-125 level. Methods. Between May 2006 and July 2008, 16 patients with advanced EOC (stages III and IV) who had achieved complete response after cytoreductive surgery and platinumbased chemotherapy were included. These patients were asymptomatic but had a rising serum CA-125 level with normal physical examination and contrast-enhanced CT scan of the abdomen and pelvis. Patients were evaluated with 18F-FDG PET-CT scan. Written informed consent was taken. Patients with a positive PET-CT scan were advised ultrasoundguided fine-needle aspiration cytology (FNAC) from the area showing increased uptake. Patients in whom FNAC was negative or inconclusive or those with negative PET-CT scan were followed up closely for the next 6 months with repeat clinical evaluation and CT scan. Results. Fifteen patients (15/16) had a positive PET-CT scan. In 9 patients the positive PET lesion was confirmed on FNAC, while in 5 patients this was confirmed on follow-up CT scan after 6 months. One patient who had a single positive lesion in the pelvis on PET-CT was initially considered falsepositive because a follow-up CT scan at 6 months did not show the lesion. However, on regular follow-up after 2 years, she was detected to have an isolated lesion in the PET-positive area which was confirmed on secondary cytoreduction. This patient was considered as true-positive in the current analysis. One patient, who had a negative PET-CT scan and a negative CT scan at 6 months’ follow-up was considered true-negative. The sensitivity and specificity of PET-CT scan was 100%. We could confirm positivity on histopathology/FNAC in 10 of the 15 (66.7%) true-positive cases. Conclusion. 18F-FDG PET-CT scan is a sensitive and specific technique for early diagnosis of relapse in asymptomatic EOC patients with rising CA-125. However, its role in the management of recurrent ovarian cancers needs further evaluation.

Doughnut sign on FDG-PET scan in a ruptured lung hydatid cyst.

A 13-year-old girl, complained of fever and cough with mucoid expectoration associated with episodes of streaky haemoptysis. Past history was not significant. On examination vital signs were normal with a pulse oximetry saturation of 98 percent. Chest examination revealed decreased breath sounds in the left mammary and infra-mammary area.

Utility of PET in unknown primary with cervical metastasis: A retrospective study.

Background: FDG-PET is recommended as an investigation in unknown primary tumors, but its definitive role and cost effectiveness are yet to be established. Aims: dditional value of FDG-PET over conventional imaging in unknown primary tumors with cervical metastasis. Setting and Design: Retrospective study in a tertiary level oncology centre. Materials and Methods: A total of 112 patients were divided into three groups; 53 with conventional modalities (either computed tomography or magnetic resonance imaging) (group I), 59 with FDG-PET (group II), and group III (subgroup of group II) with both (40 patients). Statistical Analysis: Sensitivity and specificity of both conventional modality and PET were calculated. Association between neck nodes and distant metastasis was analysed using multivariate logistic regression analysis. Results: Sensitivity and specificity for conventional modalities was 92.3% and 50% and sensitivity and specificity of FDG-PET was 92.8% and 71.4%, respectively. FDG-PET detected metastasis in 52.54% of patients. Multivariate logistic regression analysis showed statistically significant association between distant metastasis and multiplicity of nodes (N2b, N2c) (P = 0.007). Among all patients with low neck nodes in group II, FDG-PET detected primaries in 12 patients, 9 of which were infraclavicular (75%). FDG-PET added information to conventional imaging in 32.5% of patients and influenced an overall change in management in 38.9% of patients. Conclusions: FDG-PET is a valuable tool influencing change of management in unknown primary with cervical metastasis. It is recommended especially in the presence of low or multiple neck nodes in view of high incidence of infraclavicular primary and distant metastasis, respectively.

Complimentary role of FDG-PET imaging and skeletal scintigraphy in the evaluation of patients of prostate carcinoma.

Prostate cancer is one of the most common malignancies of elderly males. Management depends on the accurate estimation of disease both at initial diagnosis and in its subsequent course. In the present study, we evaluated the diagnostic utility of positron emission tomography with 18 F-fluorodeoxyglucose (FDG-PET) in patients having prostate cancer. The findings were compared with the results of bone scan (BS) for the detection of bone metastases. Sixteen patients (age range, 55-83 years) with confirmed diagnosis of prostate cancer were included in the prospective study. Three patients had undergone bilateral orchidectomy, 1 had hormonal therapy, 9 had undergone both, and 3 had no therapy. All the patients underwent wholebody BS and FDG-PET within 1 week. Interpretation of BS and FDG-PET were performed qualitatively. Osseous abnormalities detected by both methods were compared. Involvement of the disease in other sites as seen on FDG-PET was also noted. BS detected 197 osseous lesions, whereas FDG-PET could detect 97 (49%) bone lesions. However, in 3 patients without any prior therapeutic intervention, FDG-PET results were superior or equivalent to that of BS. FDG-PET also detected extensive involvement of the disease in the bone marrow in 4 patients, lymph node metastases at various sites in 8, liver metastases in 2, and lung metastases in 1 patient. FDG-PET could demonstrate less number of osseous metastases in comparison with BSs, but the results have to be interpreted in the background of prior treatment administered and the tumor biology of the lesion. It is evident that FDG-PET could detect the unknown soft tissue involvement of the disease with good sensitivity, which might play an important role in the management of prostate cancer. Overall, in the absence of novel PET tracers, both skeletal scintigraphy and FDG-PET imaging can play a complimentary role in the management of prostate cancer.

Exploring the role of FDG-PET in the assessment of bone marrow involvement in lymphoma patients as interpreted by qualitative and semiquantitative disease metabolic activity parameter.

Bone marrow biopsy (BMB) is currently the standard method to evaluate marrow involvement in malignant lymphomas. However, there exist a number of pitfalls in this technique that can have important implications for initial staging, prognostification, and treatment of the disease. The present study was undertaken to investigate the utility of FDG-PET imaging in the detection of bone marrow involvement in untreated lymphoma patients. Forty untreated patients (36 males and 12 females) with either Hodgkin's disease (HD) (n = 17) or non-Hodgkin's lymphoma (NHL) (n = 31) underwent whole body FDG-PET study for disease evaluation. Bone marrow uptake of FDG was graded as absence or presence of disease activity at marrow sites by qualitative assessment. Semiquantitative analysis involved deriving disease metabolic index (DMI) using the following formula: DMI = SUV max of suitable circular ROI over PSIS or trochanteric region/ SUVmax of similar ROI over adjoining background. Findings of BMB and FDG-PET were compared for final analysis. Eleven out of 17 HD patients (12 males and 5 females) demonstrated concordance between FDG PET findings and BMB reports. Remaining 6 cases showed discordance of FDG-PET demonstrating presence of marrow involvement at marrow sites and uninvolved marrow on BMB. Twenty six of the 31 NHL cases (24 males and 7 females) demonstrated concordance between FDG PET findings and BMB reports. Remaining 5 cases showed discordance of FDG-PET demonstrating presence of marrow involvement at marrow sites and uninvolved marrow on BMB. All the BMB positive patients (2 of HD and 5 of NHL) demonstrated disease activity in bone marrow on FDG-PET study. All patients with absence of disease activity at marrow sites on FDG-PET scan (9 of HD and 21 of NHL) had histology proven uninvolved marrow. The quantitative assessment by DMI showed a mean of >2.5 in HD and NHL patients at the PSIS region and the trochanteric region bilaterally in cases of bone marrow involvement by the disease. FDG-PET is a useful adjuvant to BMB for the evaluation of bone marrow involvement in lymphoma patients. The disease metabolic index of >2.5 at the marrow sites can serve as a semiquantitative parameter for such diagnosis on FDG-PET in untreated patients of lymphoma.

PET and PET-CT imaging in infection and inflammation: Its critical role in assessing complications related to therapeutic interventions in patients with cancer.

Over the past decade, there has been an increasing evidence of false-positive FDG uptake in several infectious diseases and aseptic inflammatory processes. With the widespread application of FDG-PET imaging in oncology, the interpreting physicians have come across these conditions frequently leading to false-positive diagnosis. Such conditions can coexist with metastatic lesions in patients with cancer, and hence, early and accurate diagnosis or exclusion of infection and inflammation is of utmost importance for the optimal management of these patients. Also, this powerful imaging modality can play an invaluable role for the appropriate management of these complicated benign conditions. The present communication on this non-oncological application of FDG is intended as an educative primer for practicing oncologists on this very important aspect of PET-CT imaging with an ultimate aim for bettering patient management.

PET/CT-guided radiation therapy planning: From present to the future.

Molecular imaging using 18F-fluoro-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been successfully used in the diagnosis, initial staging, and response assessment of various malignant tumors. Advances in radiation therapy planning and delivery have ushered in the era of high-precision conformal radiotherapy allowing generation of dose distributions that conform closely to the shape of the target volume while minimizing high-dose regions in the surrounding normal tissues. Traditionally, radiation therapy planning has relied heavily on CT imaging, but recent times have witnessed tremendous enthusiasm for the use of PET/CT-guidance in radiotherapy planning. This has been largely stimulated by widespread availability and integration with treatment planning systems. However, several issues need to be addressed and challenges overcome to realize the full potential of this exciting technology. Integrating PET/CT fusion imaging into routine clinical practice can be challenging due to technical, administrative, financial, geographic, and personnel issues. Concerted efforts are urgently needed for the development of guidelines for appropriate application of this technology using standardized methodology. There is accumulating evidence that incorporating PET/CT imaging in radiotherapy planning for lung cancer, head and neck cancer and cervical cancer has a significant impact. This review highlights the promises and pitfalls of PET/CT imaging in radiotherapy treatment planning with a critical appraisal of the current best evidence for its application in the modern radiotherapy clinic, and provides a sneak preview into the future of such technology.

Non-FDG PET in the practice of oncology.

Fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET) is utilized in more than 90% of cancers in staging, re-staging, assessing therapy response and during the follow-up. However, not all tumors show significant increase of metabolic activity on FDG-PET imaging. This is particularly true for prostate cancer, neuroendocrine tumors and hepatic tumors. In this review we have considered those already used for clinical applications such as 11C- and 18F-Choline, 11C-Methionine and 18F-FET, 18F-DOPA, 68Ga-DOTA-somatostatine analogues, 11C-Acetate and 18F-FLT. Choline presents a high affinity for malignant prostate tissue, even if low grade. Choline can be labeled with either 11C or 18F, the former being the preference due to lower urinary excretion and patients exposure. The latter is more useful for possible distribution to centers lacking in on-site cyclotron. Methionine is needed for protein synthesis and tumor cells require an external supply of methionine. These tracers have primarily been used for imaging of CNS neoplasms. The most appropriate indication is when conventional imaging procedures do not distinguish between edema, fibrosis or necrosis and disease relapse. In addition, the uptake of 11C-Methionine is proportional to the tumor grade and, therefore, the maximum small unilamellar vesicles (SUV) inside the brain mass before therapy is somehow considered a prognostic value. Neuroendocrine tumors (carcinoids, pheocromocytoma, neuroblastoma, medullary thyroid cancer, microcytoma, carotid glomus tumors, and melanoma) demonstrate an increased activity of L-DOPA decarboxylase, and hence they show a high uptake of 18FDOPA. For the study of NETs, 68Ga-DOTA-TOC/DOTA-NOC has been introduced as PET tracer. This compound for PET imaging has a high affinity for sst2 and sst5 and has been used in the detection of NETs in preliminary studies; 68Ga-DOTA-NOC PET is useful before metabolic radiotherapy in order to evaluate the biodistribution of the therapeutic compound; 18F-FLT is a specific marker of cell proliferation and the most important field of application of FLT is lung cancer. Other tracers are used in PET utilized as markers of hypoxia inside big neoplastic masses include 18F-MISO, 64Cu-ATSM, 18F-EF5, which highlight the presence of hypoxic areas are useful for patients that must be treated with radiotherapy.

Clinical applications of positron emission tomography-computed tomography in oncology.

Positron emission computed tomography (PET) is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a variety of radiopharmaceuticals. The ability of PET to study various biological processes (glucose, amino acid, phospholipids, receptors etc.) opens up new possibilities for both day-to-day clinical use and research applications in the practice of oncology. Addition of CT to PET has resulted in better specificity and sensitivity than either of the modalities alone, as the combined approach has the ability to demonstrate functional and structural details in the same setting. F-18 fluoro-2-deoxy-D-glucose (FDG), an analogue of glucose, is the most commonly used radiotracer in PET-CT imaging. The F-18 FDG uptake in tumor cells is directly proportional to glucose metabolism in the cells. Since glucose metabolism is increased several folds in the malignant tumors, PET-CT images show preferential higher FDG uptake in malignant cells as compared to normal cells. F-18 FDG PET-CT has been found to be useful in the initial staging, detection of recurrent disease and monitoring the response to the therapy in malignancies including lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer, breast cancer.

Positron emission tomography / computerized tomography evaluation of primary Hodgkin's disease of liver.

Occurrence of primary Hodgkin's lymphoma (PHL) of the liver is extremely rare. We report on a case of a 60-year-old male who presented with liver mass and B-symptomatology. Hepatoma or hepatic metastasis from a gastrointestinal primary was initially suspected. Tumor markers like AFP, CEA, Total PSA, and CA-19.9 were within normal limits. Positron Emission Tomography / Computerized Tomography (PET/CT) revealed a large hepatic lesion and a nodal mass in the porta hepatis. A liver biopsy was consistent with Hodgkin's lymphoma. There was complete regression of the hepatic lesion and evidence of shrinkage of the nodal mass following four cycles of chemotherapy. 18F Fluro -de-oxy Glucose (FDG) PET / CT in this case helped in establishing a primary hepatic lymphoma by demonstrating the absence of pathologically hypermetabolic foci in any other nodes or organs. PET / CT scan is a useful adjunct to conventional imaging and histopathology, not only to establish the initial diagnosis, but also to monitor treatment response in PHL.

Vesicoureteric reflux deterioration in monozygotic twins.

Primary vesicoureteric reflux (VUR) is the most common inherited structural urinary tract disorder, conforming closely to autosomal dominant transmission. A pair of monozygotic siblings is described exhibiting a remarkably parallel clinical course. VUR grade II was diagnosed in girl A during urinary tract infection at the age of 2 yr; screening of her asymptomatic sister (girl B) revealed the same. Renal cortical scintigraphy unveiled unilateral hypo-dysplasia in both the twins. Despite trimethoprime-sulfamethoxazole prophylaxis, infection recurred in girl A after 7 months, while girl B had a first episode 2 months later that prompted regimen switch to nitrofurantoin. Follow-up at the age of 4 depicted bilateral reflux deterioration; an urodynamics study that followed revealed functional bladder instability in both girls and the oral antispasmodic oxybutynin was initiated with good results. Evaluation for reflux should be prompt in infants with urinary infection. Patient siblings display a higher relative reflux risk, being highest in identical twins. Heredity issues, the impact of age and dysfunctional voiding in the clinical course, and the contribution of nuclear medicine in VUR management are discussed.

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.

Cancer screening with whole-body PET/CT for healthy asymptomatic people in Japan: re-evaluation of its test validity and radiation exposure.

The use of Positron Emission Tomography (PET) or PET/CT for voluntary cancer screening of asymptomatic individuals is becoming common in Japan, though the utility of such screening is still controversial. This study estimated the general test validity and effective radiation dose for PET/CT cancer screening of healthy Japanese people by evaluating four standard indices (sensitivity, specificity, positive/negative predictive values), and predictive values with including prevalence for published literature and simulation-based Japanese data. CT and FDG-related dosage data were gathered from the literature and then extrapolated to the scan parameters at a model PET center. We estimated that the positive predictive value was only 3.3% in the use of PET/CT for voluntary cancer screening of asymptomatic Japanese individuals aged 50-59 years old, whose average cancer prevalence was 0.5%. The total effective radiation dose of a single whole-body PET/CT scan was estimated to be 6.34 to 9.48 mSv for the average Japanese individual, at 60 kg body weight. With PET/CT cancer screening in Japan, many healthy volunteers screened as false positive are exposed to at least 6.34 mSv without getting any real benefit. More evaluation concerning the justification of applying PET/CT for healthy people is necessary.

Role of radionuclide scintigraphy in the detection of parathyroid adenoma.

BACKGROUND: Preoperative detection of parathyroid adenoma is a diagnostic challenge. The sonography and computerized tomography (CT) scan demonstrate high sensitivity but low specificity. The advent of radionuclide scanning technique has enhanced the specificity in this context. AIM: We undertook a study to assess the role of radionuclide scanning in suspected cases of parathyroid adenomas. MATERIALS AND METHODS: Totally 28 cases were incorporated in the study. The suspicion was raised either due to raised PTH levels or recurrent calcinosis. Most of these patients had estimation of calcium done as a routine or specific investigation. The parathyroid scan was performed using either of the two techniques - Dual isotope subtraction or Sestamibi washout technique. We also used the recent approach of fusion imaging (CT + tomographic nuclear images) in selected cases. RESULTS: There were 16 true positive, 10 true negative, 1 false negative and 1 equivocal scan findings. The findings were compared with sonography, CT Scan and PTH values. The true positive yield in our study was 57%, true negative 35% and the overall sensitivity and specificity was found to be 94% and 100% respectively. CONCLUSION: We conclude that parathyroid scintigraphy is a reliable and sensitive technique in the preoperative detection of parathyroid adenomas and should be the first choice of imaging modality in suspicion of parathyroid adenoma.