Optimization of Bayesian penalized likelihood reconstruction for 68 Ga-prostate-specific membrane antigen-11 PET/computed tomography.

OBJECTIVE: The objective of this study is to determine the optimal ß value for clinical use in digital 68 Ga-prostate-specific membrane antigen (PSMA-11) PET/computed tomography (CT) imaging. METHODS: 68 Ga PSMA PET/CT of 21 patients with prostate cancer were reconstructed using block-sequential regularized expectation maximization ( ß value of 400-1600) and ordered subsets expectation maximization. Nine independent blinded readers evaluated each reconstruction for overall image quality, noise level and lesion detectability. Maximum standardized uptake value (SUVmax) of the most intense lesion, liver SUVmean and liver SUV SD were recorded. Lesions were then subdivided according to uptake and size; the SUVmax of these lesions were analyzed. RESULTS: There is a statistically significant correlation between improvement in image quality and ß value, with the best being ß 1400. This trend was also seen in image noise ( P  < 0.001), with the least image noise reported with ß 1400. Lesion detectability was not significantly different between the different ß values ( P  =  0.6452). There was no statistically significant difference in SUVmax of the most intense lesion ( P  = 0.9966) and SUVmean of liver background between the different ß values ( P  = 0.9999); however, the SUV SD of the liver background showed a clear trend, with the lowest with ß 1400 ( P  = 0.0008). There was a decreasing trend observed in SUVmax when ß values increased from 800 to 1400 for all four subgroups, and this decrease was greatest in small and low uptake lesions. CONCLUSION: Bayesian penalized likelihood reconstruction algorithms improve image quality without affecting lesion detectability. A ß value of 1400 is optimal.

18F-FDG PET/CT Manifestations of IgG4-related Disease.

Immunoglobulin G4-related disease (IgG4-RD) was not recognised as a systemic condition until 2003, when extra pancreatic manifestations were identified in patients with autoimmune pancreatitis. Since then, IgG4-RD has been described to involve virtually every organ system. It is highly responsive to immunosuppressants but can have detrimental effects if left untreated. Early recognition of the disease is, therefore, critical. The diagnosis of IgG4-RD is frequently challenging owing to its non-specific clinical manifestations, indolent nature and broad differential diagnoses. Although histopathological examination remains the cornerstone of diagnosis, imaging plays an important role in establishing extent of disease and identifying areas suitable for biopsy. 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) has been demonstrated to be useful in assessing organ involvement, guiding biopsy and monitoring disease response. The 18F-FDG PET/CT scan is highly sensitive and able to evaluate multiorgan involvement in a single examination, a key advantage over conventional imaging modalities. A potential pitfall is its low specificity. As such, detailed knowledge of the imaging findings in IgG4-related disease is required to avoid misdiagnosis. This pictorial review aims to depict the diverse spectrum of imaging findings of IgG4-RD and the key imaging features to distinguish it from other important differential diagnoses.

Recombinant human thyrotropin versus thyroid hormone withdrawal in an Asian population.

CONTEXT: To prepare for radioactive iodine therapy in post total thyroidectomy patients with well-differentiated thyroid cancer (WDTC), either thyroid hormone withdrawal (THW) or administration of recombinant human thyrotropin (rhTSH) can be performed. OBJECTIVE: Our objective is to compare quality of life (QoL) parameters using the SF-36v2 questionnaire (Short Form health survey) and a self-evaluated item, and the hypothyroid status using modified Billewicz scores in an Asian population undergoing either THW or rhTSH for remnant ablation or adjuvant treatment following total thyroidectomy for WDTC. We will also assess the proportion of patients achieving TSH level of >30 mU/L after 4 weeks of thyroid hormone withdrawal. RESULTS: Patients in the rhTSH group were better in the QoL domains of physical functioning, role functioning/physical and bodily pain, while patients in THW group were better in mental health. This was however, not statistically significant. Modified Billewicz scores were higher in patients in THW group as compared with rhTSH group and statistically significant. A total of 96.3% of patients achieved TSH level >30 mU/L after 4 weeks of THW. CONCLUSION: Clinical symptoms and signs of hypothyroidism as assessed with modified Billewicz scores were statistically significantly higher in the THW group. However, there was no statistically significant difference in QoL in the rhTSH group.

Gallium-68-Labeled Prostate-Specific Membrane Antigen-11 PET/CT of Prostate and Nonprostate Cancers.

OBJECTIVE. The purpose of this study is to provide a concise summary of the current experience with 68Ga-labeled prostate-specific membrane antigen (PSMA)-11 imaging of prostate and nonprostate malignancies and benign conditions. CONCLUSION. PSMA is overexpressed in prostate cancer and in the neovasculature of many other malignancies. The relevance of PSMA as a biologic target, coupled with advances in the design, synthesis, and evaluation of PSMA-based radionuclides for imaging and therapy, is anticipated to play a major role in patient care.

Current Status and Growth of Nuclear Theranostics in Singapore.

The concept of theranostics, where individual patient-level biological information is used to choose the optimal therapy for that individual, has become more popular in the modern era of 'personalised' medicine. With the growth of theranostics, nuclear medicine as a specialty is uniquely poised to grow along with the ever-increasing number of concepts combining imaging and therapy. This special report summarises the status and growth of Theranostic Nuclear Medicine in Singapore. We will cover our experience with the use of radioiodine, radioiodinated metaiodobenzylguanidine, peptide receptor radionuclide therapy, prostate specific membrane antigen radioligand therapy, radium-223 and yttrium-90 selective internal radiation therapy. We also include a section on our radiopharmacy laboratory, crucial to our implementation of theranostic principles. Radionuclide theranostics has seen tremendous growth and we hope to be able to grow alongside to continue to serve the patients in Singapore and in the region.

18F-Fluorodeoxyglucose-positron Emission Tomography/Computed Tomography Imaging of Metastatic Nasopharyngeal Cancer with Emphasis on the Distribution of Bone Metastases.

Distant metastases change the prognosis of patients with nasopharyngeal carcinoma (NPC) which most commonly metastasizes to the bone. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is reported as useful in imaging NPC metastases. Our study assesses the incidence and distribution of bone metastases detected by 18F-FDG PET/CT in NPC. 717 18F-FDG PET/CT scan reports of histologically proven NPC patients imaged in Singapore General Hospital, Singapore, between 2003 and 2009 were reviewed for the total number of metastases (scanned from vertex to mid-thigh) and analyzed for distribution. Of the 709 FDG avid metastases in these reports, 357/709 (50.35%) were locoregional nodal metastasis and 352/709 (49.65%) were distant metastases of which 192/709 (27.08%) of total metastases and 54.54% of distant metastases (192/352) were in the bones. The majority of the bone lesions 125/192 (65.1%) were in the axial skeleton with 109/192 (56.77%) in the lower skeleton (thoracolumbar spine, sacrum, and pelvis). The incidence of bone metastases in our study (27.08%) was higher than that reported in other studies, for example, 15% by Liu et al. and 11% (230 patients) by Caglar et al. Bone metastases have been reported in the femurs and the feet and as such some metastases may have been outside the field of view of the scans. In our study, 27% of FDG avid NPC metastases are in the bones.

Dual-phase (18)F-fluorocholine PET/CT to detect locoregional recurrence of prostate cancer: comparison between each time point of imaging and a summation scan.

OBJECTIVES: Prostate carcinoma is a major health problem, and routine imaging shows only modest results in detecting and restaging clinically localized prostate cancer recurrence. Recent studies have shown promise of radiolabeled analogues of choline for positron emission tomography (PET) scans in patients of biochemical recurrence and that sequentially incremental Fluorocholine (FCH) uptake is associated with malignancy, whereas decreasing tracer activity suggests a benign aetiology. However, this pattern of tracer uptake has not been fully validated, and no standardized (18)F-Fluorocholine ((18)F-FCH) scan protocol is in place yet. This study aimed to better define the role of dual-phase (18)F-FCH PET/computed tomography (CT) imaging using retrospective masked reading focusing on detection of locoregional recurrence/metastasis in patients with biochemical failure after definitive local primary treatment. METHODS: A total of 32 subjects were enrolled during the period 04/2010 to 05/2014 with histologically proven prostate cancer that was treated with curative intent and had biochemical recurrence. Early scans and delayed imaging of the pelvis were graded separately by blinded readers. Final evaluation using the combination of information from dual-phase studies as a "summation scan" was also performed. Maximum standardized uptake value was computed using regions of interest constructed over focal hyperactivity. Calculations were performed using Statistical Product and Service Solutions, Version 20 for Windows. A composite reference consisting of histopathology, correlation with other imaging, or serum prostate specific antigen (PSA) trend with clinical follow-up of at least 6months was used to determine the true disease status of the patient. RESULTS: Early-phase pelvis imaging sensitivity and specificity were calculated to be 73.1% and 90.9%, respectively. Late-phase pelvis imaging sensitivity and specificity were 80.8% and 100%, respectively. Summation scan sensitivity and specificity were 76.9% and 100%, respectively. The odds ratio of having recurrent disease with an uptrend of SUVmax on dual-phase imaging was 33.3. The optimal cutoff value of PSA was 1.85ng/mL with 80% sensitivity and 62.5% specificity. CONCLUSIONS: Single late-phase FCH PET/CT imaging is a reliable scan modality which can detect sites of disease at low levels of PSA which still fulfil the criteria of biochemical recurrence. This will allow clinicians to identify sites for potential biopsy or start locoregional treatment.

Gender, Race, and Age at Diagnosis as Risk Factors for Metastasis or Recurrence among 1,657 Thyroid Cancer Patients Treated with Radioiodine across 40 Years in Singapore.

BACKGROUND: To obtain descriptive data on Singaporean thyroid cancer patients treated with radioiodine and to assess gender, race, and age at diagnosis as risk factors for metastasis or recurrence. METHODS: This is a retrospective study of all thyroid cancer patients treated with radioiodine of any prescribed activity at our institution. Data collected included: age at diagnosis, gender, race, histopathological type, duration of follow-up, and metastasis at diagnosis (locoregional or distant) or recurrence at any time. Gender, race, and age at diagnosis were analyzed for possible associations with metastasis or recurrence. RESULTS: A total of 1,657 thyroid cancer patients were treated with radioiodine across a 40-year period; mean follow-up 6.4 ± 6.9 years (median 4.2 years). 656 (39.6%) patients had metastasis or recurrence over the duration of their follow-up. Male gender (odds ratio (OR) 1.38; p = 0.006), Malay race (OR 1.71; p < 0.0001), and age at diagnosis of > 46 years (OR 1.31; p = 0.007) were significantly associated with metastasis or recurrence. CONCLUSION: Male gender, Malay race, and age at diagnosis of > 46 years were significant risk factors for metastasis or recurrence in Singaporean thyroid cancer patients treated with radioiodine.

The incidence and sites of Nasopharyngeal carcinoma (NPC) metastases on FDG PET/CT scans.

INTRODUCTION: The only investigation to determine if a whole body FDG PET/CT scan is helpful in the evaluation of NPC is a study from Stanford. In this study, 26 patients with whole body PET/CT, were evaluated for lesions below adrenals and showed that 7.7% of distant metastases were below adrenals. Our study comparing distant metastases below diaphragm with Stanford study to evaluate the need for whole body PET/CT. MATERIAL AND METHODS: Reports of NPC patients in Singapore General Hospital were reviewed. The lesions were analyzed for total number and number below diaphragm. The lesions below the diaphragm were further analyzed if they were solitary or involved multiple areas and if any additional lesions were above diaphragm. RESULTS: 717 reports were included in final analysis. The number of FDG avid lesions in these reports was 709. Distant metastases represented 352 of the 709 lesions. The number of lesions below diaphragm was 152, of the lesions below diaphragm only 16 of lesions have no co-existing distant metastases above diaphragm. From these lesions, there were only 12 solitary lesions. The other 4 has concurrent metastases but all localized below diaphragm. CONCLUSION: Compared to Stanford study, number of reports is more representative in this study and the yield is much lower (7.7% versus 2.26%). From the results of our study we can consider limiting the scan area from vertex to below diaphragm. However, the symptoms and clinical presentation of the patient will further direct the requesting physician in the area to be imaged.

Effect of preconditioning by light load eccentric exercise versus heat on markers of muscle damage in collegiate males.

BACKGROUND: Delayed onset muscle soreness (DOMS) occurs following unaccustomed or intense bouts of exercise. Previous research has demonstrated that that preconditioning with low load exercise or heat relieves muscle soreness. However, actively warming up the muscles with exercise may be an effective alternative. OBJECTIVES: This study compared preconditioning effect of light load eccentric exercise and heat using microwave diathermy on markers of muscle damage in collegiate males. PATIENTS AND METHODS: Thirty six sedentary collegiate males were randomly assigned into two experimental groups: 10% Eccentric exercise group (10% ECC group) and Microwave diathermy group (MWD group). Both the groups performed 30 repetitions of maximal eccentric exercise (Max-ECC) of the elbow flexors. The 10% ECC group performed light load eccentric exercise (10% ECC), five sets, six repetitions using a dumbbell set at 10% of maximal voluntary isometric contraction strength (MVC), 2 days prior to Max-ECC. The MWD group received heat using microwave diathermy (150 watts, 20 minutes) one day prior to Max-ECC. Changes in MVC, range of motion (ROM), upper arm circumference, soreness, were assessed before and 24-72 hours after whereas serum creatine kinase activity and lactate dehydrogenase (LDH) activity up to 48 hours following the Max-ECC were compared between groups by a mixed model ANOVA. RESULTS: No significant difference (P > 0.05) were found between the groups for changes in all variables post Max-ECC, except for LDH activity showing significant interaction effect (P = 0.04). CONCLUSIONS: Preconditioning with light load eccentric exercise and heat using microwave diathermy treatment did not differ in their effects on muscle damage markers after Max-ECC. However, with time their effects on LDH activity were found to be different.

Post-thyroidectomy neck ultrasonography in patients with thyroid cancer and a review of the literature.

The importance of routine neck ultrasonography for the detection of unsuspected local or nodal recurrence of thyroid cancer following thyroidectomy (with or without neck dissection) is well documented in many journal articles and international guidelines. Herein, we present a pictorial summary of the sonographic features of benign and malignant central neck compartment nodules and cervical lymph nodes via a series of high-quality ultrasonographic images, with a review of the literature.

Use of Ga-68 DOTATATE PET/CT to confirm portal vein tumor thrombosis in a patient with pancreatic neuroendocrine tumor.

A 37-year-old man complained of increasing severity and frequency of abdominal pain over a 2-year period. Initial contrast-enhanced computed tomography of the abdomen demonstrated diffuse enlargement of the pancreas associated with a filling defect in the portal vein, splenomegaly with wedge-shaped peripheral splenic hypodensities and multiple hepatic hypodensities. Findings were suggestive of a pancreatic malignancy complicated by hepatic metastases, splenic infarcts, and portal vein thrombosis. We describe the use of gallium-68 DOTA-DPhe1, Tyr3-octreotate positron emission tomography/computed tomography (Ga-68 DOTATATE PET/CT) in confirming the diagnosis of a pancreatic neuroendocrine tumor with portal vein tumor thrombosis.

Usefulness of F-18 fluorodeoxyglucose positron emission tomography/computed tomography in a case of choriocarcinoma presenting as pulmonary embolism.

This case demonstrates the utility of performing F-18 fluorodeoxyglucose positron emission tomography/computed tomography for the investigation of an unresolving pulmonary embolus, where early diagnosis of tumor thrombus or primary neoplastic conditions of the pulmonary artery may be made. Choriocarcinoma presenting within the pulmonary artery is rare although a literature review shows that a number of important differential diagnoses of hypermetabolic pulmonary lesions should be kept in mind.