18F-FDG positron emission tomography/computed tomography in infective endocarditis

BACKGROUND

The diagnosis of infective endocarditis (IE), especially the diagnosis of prosthetic valve endocarditis (PVE) is challenging since echocardiographic findings are often scarce in the early phase of the disease. We studied the use of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in IE.

METHODS

Sixteen patients with suspected PVE and 7 patients with NVE underwent visual evaluation of 18F-FDG-PET/CT. 18F-FDG uptake was measured also semiquantitatively as maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR). The modified Duke criteria were used as a reference.

RESULTS

There was strong, focal 18F-FDG uptake in the area of the affected valve in all 6 cases of definite PVE, in 3 of 5 possible PVE cases, and in 2 of 5 rejected cases. In all patients with definite PVE, SUVmax of the affected valve was higher than 4 and TBR higher than 1.8. In contrast to PVE, only 1 of 7 patients with NVE had uptake of 18F-FDG by PET/CT in the valve area. Embolic infectious foci were detected in 58% of the patients with definite IE.

CONCLUSIONS

18F-FDG-PET/CT appears to be a sensitive method for the detection of paravalvular infection associated with PVE. Instead, the sensitivity of PET/CT is limited in NVE.

A Unique Case of Increased 18F-FDG Metabolic Activity in the Soft Tissues of the Bilateral Upper Thighs Due to Immunizations in a Pediatric Patient

A case of a 7-month-old white female who was referred for 18F-fluorodeoxyglucose (FDG) Positron emission tomography/computed tomography (PET/CT) initial evaluation of a lytic skull lesion with presumed diagnosis of Langerhans cell histiocytosis is described. Incidentally, she was found to have hypermetabolic nodules in the soft tissues of her anterior thighs.

Reversal of cerebral glucose hypometabolism on positron emission tomography with electroconvulsive therapy in an elderly patient with a psychotic episode

AB, a 74-year-old Caucasian woman, was admitted for acute onset of psychosis, anxiety, and cognitive impairment. Pharmacotherapy was unsuccessful and the patient was referred for electroconvulsive therapy (ECT). Pre-ECT, ¹⁸ F-fluorodeoxyglucose-positron emission tomography (PET)/computed tomography showed extensive frontal, parietal, and temporal cortical hypometabolism suggestive of a neurodegenerative disease. After eight ECT sessions, the psychotic and anxiety symptoms as well as the cognitive impairment resolved. The rapid improvement in symptoms was more suggestive of a psychotic episode rather than dementia. Two days after the ECT course, ¹⁸ F-fluorodeoxyglucose-PET/computed tomography showed improvements in cerebral cortical hypometabolism, especially in the left parietal cortex, left temporal/occipital cortex. and bifrontal regions. At a follow-up visit 2 months after the ECT course, the psychotic episode was still in remission, and ¹⁸ F-fluorodeoxyglucose-PET/computed tomography continued to show improved cerebral cortical hypometabolism in these areas. This case illustrated the effect of ECT in reversing cerebral glucose hypometabolism on PET. The improvement in cerebral glucose hypometabolism may represent the neurophysiological mechanism of ECT in the treatment of a psychotic episode. Improved cerebral glucose hypometabolism was present 2 months post-ECT, which suggests that ECT caused sustained functional neural changes.

An Extremely Rare Intersection: Neurolymphomatosis in a Patient with Burkitt Lymphoma Detected by 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Neurolymphomatosis (NL) is a rarely seen neurologic involvement of the systematic lymphoma. Its diagnosis is challenging, and requires biopsy. In cases where biopsy is not appropriate, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may aid in diagnosis. Here, we present a 54-year old male patient diagnosed with Burkitt lymphoma who underwent FDG-PET/CT in order to evaluate the treatment response after chemotherapy and radiotherapy. On viewing PET/CT images of the patient who complained of pain and weakness in his upper extremities after therapy, linear FDG uptake was observed in bilateral cervical 5 (C5), left cervical 6 (C6), bilateral cervical 7 (C7), and right lumbar 4 (L4) nerve roots. Magnetic resonance imaging (MRI) revealed dilation and thickening of nerve roots consisted with FDG uptake observed on PET/CT images. Since biopsy was not performed, histopathological diagnosis could not be established. However, overlapping of clinical, PET/CT, and MRI findings strongly suggested the presence of NL. As is the case of this patient, in cases with non-Hodgkin lymphoma, a combined evaluation of FDG-PET/CT and MRI modalities aid in the establishment of the diagnosis of NL.

Screening for distant metastases in head and neck cancer patients using FDG-PET and chest CT: validation of an algorithm

In patients with head and neck squamous cell carcinoma and high-risk factors, the combination of whole body FDG-PET and contrast-enhanced chest CT has the highest sensitivity and accuracy when screening for distant metastases. The aim of the present study was to retrospectively validate an earlier developed algorithm for interpreting the combination of screening PET and CT. The test cohort consisted of 47 consecutive HNSCC patients with high-risk factors for distant metastases, who had previously undergone FDG-PET and CT and had a minimum 12 months of follow-up. In 12 (26 %) patients, distant metastases were detected during screening or within 12-month follow-up. In patients with locoregional control during follow-up, the sensitivity and specificity were 55 % (95 % CI 23-83 %) and 97 % (95 % CI 82-99 %), respectively, for chest CT, 55 % (95 % CI 23-83 %) and 100 % (95 % CI 88-100 %), respectively, for PET and 73 % (95 % CI 39-94 %) and 100 % (95 % CI 88-100 %), respectively, for the combination of PET and CT. The proposed algorithm was considered to have been validated. In this algorithm, all FDG-PET positive scans for distant metastases (regardless of interpretation of a solid lung lesion on CT) and CT scans with suspicious pulmonary lesions of less than 5-mm diameter (regardless of FDG-PET findings) are considered positive for distant metastases.

Characteristics of 18F-fluorodeoxyglucose uptake in anastomotic sinus and fistula following rectal cancer surgery

PURPOSE

To assess the characteristics of 18F-fluorodeoxyglucose (FDG) uptake in persisting anastomotic sinus and fistula following rectal cancer surgery.

METHODS

Eight patients with anastomotic sinus and fistula were retrospectively studied.

RESULTS

A total of 13 anastomotic sinuses (n=11) and fistulas (n=2) were observed. Sixteen FDG-positron emission tomography/computed tomography studies for 13 lesions performed and 26 uptake patterns were evaluated. Twenty-one lesions were found to have diffuse increased uptake, whereas four lesions had focal uptake. There was only one lesion without FDG uptake.

CONCLUSIONS

Increased FDG uptake is frequently observed in anastomotic sinus and fistula, which should be known to avoid making wrong diagnosis.

Dual-time-point 18F-FDG PET/CT in the diagnosis of solitary pulmonary lesions in a region with endemic granulomatous diseases

OBJECTIVE

Granulomatous diseases (GDs) can be metabolically active and indistinguishable from lung cancer on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) imaging. Evaluation of solitary pulmonary lesions remains a diagnostic challenge in regions with endemic GD. This study sought to determine the efficacy of dual-time-point (DTP) ¹⁸F-FDG PET/computed tomography (CT) imaging in diagnosing solitary pulmonary lesions from such regions.

METHODS

A total of 50 patients with solitary pulmonary nodules or masses with confirmed histopathological diagnoses underwent DTP ¹⁸F-FDG PET/CT imaging at 1 and 3 h after tracer injection. The maximum standardized uptake value (SUV_max) on early and delayed scans (SUV_1h and SUV_3h, respectively) and retention index (RI) were calculated for each pulmonary lesion. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the parameters.

RESULTS

There were 37 malignant and 13 benign solitary pulmonary lesions. Eight of the 13 (62 %) benign lesions were GDs. The sensitivity/specificity/accuracy of SUV_1h, SUV_3h and RI were 84/69/80 %, 84/85/84 %, and 81/54/74 %, respectively. SUV_3h had the best diagnostic performance, especially regarding specificity. The values of SUV_1h and SUV_3h were significantly different between malignant lesions and GD, while the RI values of malignant lesions and GD were both high (18.6 ± 19.5 and 18.7 ± 15.3 %, respectively; P = not significant).

CONCLUSION

SUV_3h appeared to improve the diagnostic specificity of ¹⁸F-FDG PET/CT in evaluating solitary pulmonary lesions from regions with endemic GD.

Prognostic Significance of FDG Uptake of Bone Marrow on PET/CT in Patients With Non-Small-Cell Lung Cancer After Curative Surgical Resection

BACKGROUND

This study evaluated the relationship between ¹⁸F-fluorodeoxyglucose (FDG) uptake in bone marrow (BM) on positron emission tomography (PET)/computed tomography (CT) imaging and serum inflammatory markers and assessed the prognostic value of FDG uptake of BM in patients with non-small-cell lung cancer (NSCLC) who underwent curative surgical resection.

PATIENTS AND METHODS

We retrospectively enrolled 110 NSCLC patients who underwent FDG PET/CT imaging and subsequent curative surgical resection. The maximum standardized uptake value of NSCLC (Tmax), mean FDG uptake of BM (BM SUV), and BM to liver uptake ratio (BLR) were measured. The relationships between BM SUV, BLR, and serum inflammatory markers were evaluated and the prognostic significance of PET/CT parameters for predicting recurrence-free survival (RFS) and overall survival (OS) were assessed.

RESULTS

BM SUV and BLR were significantly associated with serum C-reactive protein (CRP) level, white blood cell count, and the neutrophil to lymphocyte ratio (NLR). BLR was also significantly correlated with serum albumin and the platelet to lymphocyte ratio. In univariate analysis, tumor, node, metastases (TNM) stage, serum CRP level, NLR, Tmax, and BLR were significant prognostic factors for RFS and OS, whereas histopathology and tumor size were significant prognostic factors for RFS. In multivariate analysis, BLR, histopathology, TNM stage, and Tmax were independent prognostic factors for RFS and TNM stage and Tmax were independent prognostic factors for OS.

CONCLUSION

FDG uptake of BM on PET/CT imaging was correlated with serum inflammatory markers and was an independent predictor for RFS, along with FDG uptake of NSCLC.

Late metastatic recurrence of penile carcinoma after 10 years: Demonstration with (18)F-fluorodeoxyglucose positron emission tomography/computed tomography

Penile cancer is rare cancer. While inguinal and pelvic nodal metastasis is common, distant metastasis is rare. We here present the interesting case of a 59-year-old male patient with penile carcinoma, previously treated with penectomy and inguinal lymphadenectomy 10 years earlier. He presented with bone pains and given history of malignancy he was referred for an (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT). PET/CT demonstrated multiple (18)F-FDG avid bone and lung metastases. No locoregional disease was seen. Biopsy from a lung nodule confirmed the diagnosis, and the patient was started on palliative chemotherapy.

Usefulness of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in dermatofibrosarcoma protuberans on treatment with imatinib

Dermatofibrosarcoma protuberans (DFSP) is a rare locally aggressive tumor with distant metastases being unusual. We present a case of metastatic DFSP treated with imatinib showing complete metabolic response to treatment.

Clinical usefulness of post-operative 18F-fluorodeoxyglucose positron emission tomography-computed tomography in canine hemangiosarcoma

This report describes the usefulness of positron emission tomography-computed tomography (PET-CT) for evaluating recurrent or residual tumors following surgery. CT and 18F-fluorodeoxyglucose PET-CT were pre- and post-operatively applied to multiple masses in a dog with hemangiosarcoma. The distinction between the left subcutaneous mass and the peritoneum was clarified on pre-operative CT examination, and malignancy was suspected based on PET-CT. A recurrent or residual tumor in the left subcutaneous region was suspected on post-operative PET-CT, and confirmed through histopathologic examination.

Evaluation of Apoptosis with 99mTc-rhAnnexin V-128 and Inflammation with 18F-FDG in a Low-Dose Irradiation Model of Atherosclerosis in Apolipoprotein E-Deficient Mice

Low-dose radiation in apolipoprotein E-deficient (ApoE^-/-) mice has a protective effect with less subsequent atherosclerosis. Inflammation and apoptosis play major roles in the development of atherosclerosis. We evaluated the temporal pattern of the development of histologic atherosclerosis, inflammation with ¹⁸F-FDG, and apoptosis with ^99mTc-rhAnnexin V-128 at 3 time points.

METHODS

ApoE^-/- mice were fed a high-fat diet, exposed to low-dose ⁶⁰Co γ-radiation of 25 mGy at 2 mo of age, and evaluated within 1 wk (2-mo group), 1 mo (3-mo group), and 2 mo (4-mo group) from the time of radiation. Mice were divided into 3 subgroups and each received ¹⁸F-FDG, ^99mTc-rhAnnexin V-128, or no radiotracer for autoradiography. Mice underwent euthanasia and aortic root dissection. The extent of atherosclerosis was determined by en face and Oil red O imaging. Aortic arch inflammation (¹⁸F-FDG) and apoptosis (^99mTc-rhAnnexin V-128) were determined with digital autoradiography. Aortic sinus sections were stained with Sudan IV for assessment of lesion area and stage, antiCD68 antibody for inflammation and anti-cleaved-caspase 3 antibody for apoptosis.

RESULTS

The extent of aortic atherosclerosis increased from 2 to 3 mo and from 3 to 4 mo. Inflammation (CD68) decreased and apoptosis (anti-cleaved-caspase 3 antibody) increased in aortic sinus slices measured as percentage of lesion by 4 mo. With increasing lesion stage, lesion inflammation decreased and lesion apoptosis increased. Aortic arch inflammation (¹⁸F-FDG uptake) did not differ over time and did not correlate with average lesion stage. However, aortic arch apoptosis (^99mTc-rhAnnexin V-128) increased significantly by 4 mo and correlated with average lesion stage. There were no differences between the treatment subgroups (¹⁸F-FDG, ^99mTc-rhAnnexin V-128, or no radiotracer).

CONCLUSION

The temporal pattern of development of inflammation and apoptosis differ during the development of atherosclerosis in ApoE^-/- mice treated with low-dose radiation. Advanced lesions are characterized by increased apoptosis and either less or similar amounts of inflammation, shown on immunohistochemistry and autoradiography. Treatment with radiotracers had no significant effects on extent of atherosclerosis, inflammation, or apoptosis.

Expression and clinical significance of glucose transporter-1 in pancreatic cancer

Increasing evidence has demonstrated that malignant cells exhibit increased glucose uptake, which facilitates survival and growth in a hypoxic environment. The glucose transporter-1 (GLUT-1) is overexpressed in a variety of malignant tumors. However, the association between GLUT-1 expression and clinicopathological factors, ¹⁸F-fluorodeoxyglucose uptake and tumor proliferation in pancreatic cancer has not been investigated to date. In the present study, the expression of GLUT-1 in 53 pancreatic cancer tissues was analyzed, which revealed that GLUT-1 was overexpressed in pancreatic tissue and correlated with poor prognosis and clinicopathological characteristics, including increased tumor size, clinical stage and lymph node metastasis, maximum standardized uptake value (SUV_max) and Ki-67 expression. The receiver operating characteristic curve analysis indicated that a cut-off SUV_max value of 4.830 was associated with optimal sensitivity (88%) and specificity (71.4%) for the detection of strong positive GLUT-1 expression. In addition, as the expression of GLUT-1 was found to correlate with Ki-67 expression, GLUT-1 may exhibit a significant effect on cell proliferation in pancreatic cancer. Overall, these findings indicate that GLUT-1 may represent a prognostic indicator, and a potential therapeutic target for pancreatic cancer.

The effects of 18-h fasting with low-carbohydrate diet preparation on suppressed physiological myocardial (18)F-fluorodeoxyglucose (FDG) uptake and possible minimal effects of unfractionated heparin use in patients with suspected cardiac involvement sarcoidosis

BACKGROUND

(18)F-fluorodeoxyglucose (FDG) PET plays an important role in the detection of cardiac involvement sarcoidosis (CS). However, diffuse left ventricle (LV) wall uptake sometimes makes it difficult to distinguish between positive uptake and physiological uptake. The aims of this study were to evaluate the effects of 18-h fasting with low-carbohydrate diet (LCD) vs a minimum of 6-h fasting preparations on diffuse LV FDG uptake and free fatty acid (FFA) levels in patients with suspected CS.

METHODS

Eighty-two patients with suspected CS were divided into 2 preparation protocols: one with a minimum 6-h fast without LCD preparation (group A, n = 58) and the other with a minimum 18-h fast with LCD preparation (group B, n = 24). All patients also received intravenous unfractionated heparin (UFH; 50 IU/kg) before the injection of FDG.

RESULTS

Group A showed a higher percentage of diffuse LV uptake than did group B (27.6 vs 0.0%, P = .0041). Group B showed higher FFA levels (1159.1  ±  393.0, 650.5  ±  310.9 μEq/L, P < .0001) than did group A. Patients with diffuse LV uptake (n = 16) showed lower FFA levels than did other patients (n = 66) (432.1  ±  296.1, 888.4  ±  381.4 μEq/L, P < .0001). UFH administration significantly increased FFAs in both groups, even in the patients with diffuse LV FDG uptake.

CONCLUSIONS

The 18-h fast with LCD preparation significantly reduced diffuse LV uptake and increased FFA levels. In particular, the FFA level was significantly lower in patients with LV diffuse uptake than in patients without LV diffuse uptake. Acutely increasing plasma FFA through the use of UFH may not have a significant role in reducing physiological LV FDG uptake.

Diverging longitudinal changes in astrocytosis and amyloid PET in autosomal dominant Alzheimer's disease

See Schott and Fox (doi: 10.1093/brain/awv405 ) for a scientific commentary on this article.

Alzheimer’s disease is a multifactorial dementia disorder characterized by early amyloid-β, tau deposition, glial activation and neurodegeneration, where the interrelationships between the different pathophysiological events are not yet well characterized. In this study, longitudinal multitracer positron emission tomography imaging of individuals with autosomal dominant or sporadic Alzheimer’s disease was used to quantify the changes in regional distribution of brain astrocytosis (tracer ¹¹ C-deuterium-L-deprenyl), fibrillar amyloid-β plaque deposition ( ¹¹ C-Pittsburgh compound B), and glucose metabolism ( ¹⁸ F-fluorodeoxyglucose) from early presymptomatic stages over an extended period to clinical symptoms. The 52 baseline participants comprised autosomal dominant Alzheimer’s disease mutation carriers ( n = 11; 49.6 ± 10.3 years old) and non-carriers ( n = 16; 51.1 ± 14.2 years old; 10 male), and patients with sporadic mild cognitive impairment ( n = 17; 61.9 ± 6.4 years old; nine male) and sporadic Alzheimer’s disease ( n = 8; 63.0 ± 6.5 years old; five male); for confidentiality reasons, the gender of mutation carriers is not revealed. The autosomal dominant Alzheimer’s disease participants belonged to families with known mutations in either presenilin 1 ( PSEN1 ) or amyloid precursor protein ( APPswe or APParc ) genes. Sporadic mild cognitive impairment patients were further divided into ¹¹ C-Pittsburgh compound B-positive ( n = 13; 62.0 ± 6.4; seven male) and ¹¹ C-Pittsburgh compound B-negative ( n = 4; 61.8 ± 7.5 years old; two male) groups using a neocortical standardized uptake value ratio cut-off value of 1.41, which was calculated with respect to the cerebellar grey matter. All baseline participants underwent multitracer positron emission tomography scans, cerebrospinal fluid biomarker analysis and neuropsychological assessment. Twenty-six of the participants underwent clinical and imaging follow-up examinations after 2.8 ± 0.6 years. By using linear mixed-effects models, fibrillar amyloid-β plaque deposition was first observed in the striatum of presymptomatic autosomal dominant Alzheimer’s disease carriers from 17 years before expected symptom onset; at about the same time, astrocytosis was significantly elevated and then steadily declined. Diverging from the astrocytosis pattern, amyloid-β plaque deposition increased with disease progression. Glucose metabolism steadily declined from 10 years after initial amyloid-β plaque deposition. Patients with sporadic mild cognitive impairment who were ¹¹ C-Pittsburgh compound B-positive at baseline showed increasing amyloid-β plaque deposition and decreasing glucose metabolism but, in contrast to autosomal dominant Alzheimer’s disease carriers, there was no significant longitudinal decline in astrocytosis over time. The prominent initially high and then declining astrocytosis in autosomal dominant Alzheimer’s disease carriers, contrasting with the increasing amyloid-β plaque load during disease progression, suggests astrocyte activation is implicated in the early stages of Alzheimer’s disease pathology.

The Clinical Usefulness of (18)F-Fluorodeoxyglucose Positron Emission Tomography (PET) to Predict Oncologic Outcomes and PET-Based Radiotherapeutic Considerations in Locally Advanced Nasopharyngeal Carcinoma

Purpose

We investigated ¹⁸F-fluorodeoxyglucose positron emission tomography (PET)-derived parameters as prognostic indices for disease progression and survival in locally advanced nasopharyngeal carcinoma (NPC) and the effect of high-dose radiotherapy for a subpopulation with PET-based poor prognoses.

Materials and Methods

Ninety-seven stage III and Iva-b NPC patients who underwent definitive treatment and PET were reviewed. For each primary, nodal, and whole tumor, maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis (TLG) were evaluated.

Results

Based on the C-index (0.666) and incremental area under the curve (0.669), the whole tumor TLGwas the most useful predictorfor progression-free survival (PFS); thewhole tumor TLG cut-off value showing the best predictive performance was 322.7. In multivariate analysis, whole tumor TLG was a significant prognostic factor for PFS (hazard ratio [HR], 0.3; 95% confidence interval [CI], 0.14 to 0.65; p=0.002) and OS (HR, 0.29; 95% CI, 0.11 to 0.79; p=0.02). Patients with low whole tumor TLG showed the higher 5-year PFS in the subgroup for only patients receiving intensity modulated radiotherapy (77.4% vs. 53.0%, p=0.01). In the subgroup of patients with high whole tumor TLG, patients receiving an EQD₂ ≥ 70 Gy showed significantly greater complete remission rates (71.4% vs. 33.3%, p=0.03) and higher 5-year OS (74.7% vs. 19.6%, p=0.02).

Conclusion

Our findings demonstrated that whole tumor TLG could be an independent prognostic factor and high-dose radiotherapy could improve outcomes for NPC showing high whole tumor TLG.

Evidence of 18F-FCH Uptake in Human T98G Glioblastoma Cells

AIM

Tumor and chemo/radiotherapy-damaged brain tissues are hardly distinguishable by conventional morphological imaging. (18)F-FCH was compared against (18)F-FDG in the T98G glioblastoma cell line with regard to their radiopharmaceutical uptake, in order to test its diagnostic power on brain tumor lesions.

MATERIALS AND METHODS

Equimolar amounts of (18)F-FCH and (18)F-FDG were added to human glioblastoma T98G cells and human dermal fibroblasts for 20, 40, 60, 90 and 120 min of incubation. Radiopharmaceutical uptake was expressed as a percentage of the administered dose. Cold choline was used for binding competition experiments.

RESULTS

In T98G cells (18)F-FCH was taken-up in higher amounts than 18F-FDG after 60 min. In fibroblasts, uptake was lower than 1% for both radiopharmaceuticals. Cold choline reduced the uptake of FCH to 1% similarly to fibroblasts.

CONCLUSION

Our results prove the efficacy of (18)F-FCH as a promising tracer, better than (18)F-FDG in establishing the tumor-to-background ratio in brain tumors.

(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography in patients with Kikuchi-Fujimoto disease: a nine-case series in China

This study observed the image characteristics and clinico-imaging relationships of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the patients with Kikuchi-Fujimoto disease (KFD). Nine consecutive patients with histologically proven KFD who underwent (18)F-FDG PET/CT were recruited. The (18)F-FDG uptakes of bone marrow (BM), spleen and lymph nodes (LNs) were systematically evaluated and maximum standardized uptake values (SUVmax) were measured. The number, locations and size factors of LNs were also assessed. The correlations were calculated between (18)F-FDG uptake and laboratory data and size factors of LNs, and the findings of LNs were compared between subgroups with different clinical features. (18)F-FDG uptakes were positive in the BM (SUVmax, 3.2 ± 1.2), spleen (SUVmax, 2.8 ± 0.7) and 122 affected LNs (SUVmax, 4.2 ± 2.2) for all patients. The affected LNs presented a systemically (region, 4 ± 1), multiple (number, 14 ± 5) and small-sized (long axis diameter, 11.4 ± 2.7 mm; short axis diameter, 8.0 ± 2.1 mm; area, 81.1 ± 44.6 mm(2)) pattern. The SUVmax of BM correlated to neutrophil count, and the SUVmax of affected LNs correlated to size factors and was lower in patients with long imaging interval and positive anti-nuclear antibody (ANA) (P < 0.05). We conclude that (18)F-FDG PET/CT can be characterized by the generalized distribution of relatively small-sized LNs and involvement of BM and spleen with high (18)F-FDG avidity in patients with KFD. The imaging interval, neutrophil count and ANA level should be synthetically considered during imaging evaluation.

Venous thrombosis of sarcoidosis as an unusual incidental finding on 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Sarcoidosis is defined as a multisystem granulomatous disorder of unknown cause. Venous thrombosis (VT) in the sarcoidosis is rare. The routine use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has resulted in clinicians detecting many incidental findings, which have proven to be clinically significant such as thrombosis. Here, we present a case with VT of sarcoidosis in the inferior vena cava and portal vein as an unusual incidental finding on 18F-FDG PET/CT.

18F-fluorodeoxyglucose positron emission tomography/computed tomography for primary thyroid langerhans histiocytosis: A case report and literature review

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disease, with an incidence rate of 4.0-5.4/1 million individuals. LCH encompasses a spectrum of disorders with diverse clinical presentations ranging from a single organ to multiple organ involvement. LCH rarely involves the thyroid gland. We presented a case with LCH of thyroid gland. The patient had painless progressive neck enlargement and then diabetes insipidus. Ultrasonic scan and magnetic resonance imaging scan revealed nodular goiter and pituitary stalk enlargement, respectively. Histopathological analysis revealed features of histiocytoid cells. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) was performed in order to rule out the presence of whole body infiltration. 18F-FDG PET/CT also demonstrated increased uptake in the thickening pituitary stalk and maxillofacial skin lesion, in addition to the bilateral thyroid nodules, CT showed the left lung nodule and the skull destruction without 18F-FDG uptake. This report emphasizes the role of 18F-FDG PET/CT in multiple organs involvement of patients with LCH.

Adult granulosa cell tumor presenting with massive ascites, elevated CA-125 level, and low (18)F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography

Adult granulosa cell tumors (AGCTs) presenting with massive ascites and elevated serum CA-125 levels have rarely been described in the literature. An ovarian mass, massive ascites, and elevated serum CA-125 levels in postmenopausal women generally suggest a malignant ovarian tumor, particularly advanced epithelial ovarian cancer. AGCT has low ¹⁸F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography due to its low metabolic activity. In the present report, we describe a case of an AGCT with massive ascites, elevated serum CA-125 level, and low ¹⁸F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography.

Association Between (18)F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

PURPOSE

The BRAF mutation, a potential prognostic factor in papillary thyroid carcinoma (PTC), is associated with a high expression of the glucose transporter gene. We investigated which clinicopathologic factors, including BRAF mutation status, influence (18)F-fluoro-2-deoxyglucose ((18)F-FDG) avidity.

METHODS

We retrospectively reviewed 55 patients who underwent BRAF analysis from biopsy-confirmed PTC and (18)F-FDG positron emission tomography/computed tomography within 6 months before undergoing thyroid surgery from September 2008 to August 2014. Tumors were considered to be (18)F-FDG avid if the uptake was greater than that of the liver. (18)F-FDG uptake of PTCs was also analyzed semiquantitatively using SUVmax. The association between (18)F-FDG avidity and clinicopathologic variables (age, tumor size, perithyroidal extension, cervical lymph node status, and BRAF mutation status) was investigated.

RESULTS

Twenty-nine (52.7 %) of 55 patients had (18)F-FDG-avid PTCs. PTCs with the BRAF mutation showed higher (18)F-FDG avidity (24/38, 63.2 %) than those without (5/17, 29.4 %). The BRAF mutation (p = 0.025) and tumor size (p = 0.003) were significantly associated with (18)F-FDG avidity in univariate analysis, and the BRAF mutation status remained significant after adjusting for tumor size in multivariate analysis (p = 0.015). In the subgroup of tumor size ≥ 1 cm, the BRAF mutation was the only factor significantly associated with (18)F-FDG avidity (p = 0.021). The mean SUVmax of PTCs with the BRAF mutation was significantly higher than that of those without (4.89 ± 6.12 vs. 1.96 ± 1.10, p = 0.039).

CONCLUSIONS

The BRAF mutation must be one of the most important factors influencing (18)F-FDG avidity in PTCs, especially in those with a tumor size ≥ 1 cm.

18F-FLT PET/CT in the Evaluation of Pheochromocytomas and Paragangliomas: A Pilot Study

(18)F-FDG PET/CT has been proven to be a highly sensitive method for pheochromocytomas/paragangliomas (PHEOs/PGLs) associated with succinate dehydrogenase (SDH) mutations. This finding has been attributed to altered tumor cell metabolism resulting from these mutations and does not provide additional prognostic information to genotype. Therefore, identification of new biomarkers for aggressiveness is needed. A high Ki-67 index was proposed to be an additional prognostic factor. This pilot study aimed to evaluate 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) PET/CT, a PET proliferation tracer, as a potential imaging agent in a series of 12 PHEO/PGL patients with different genetic backgrounds, to compare (18)F-FLT uptake with (18)F-FDG PET/CT, and to evaluate classic factors of aggressiveness.

METHODS

Twelve patients (7 metastatic and 5 nonmetastatic) were prospectively evaluated with (18)F-FDG and (18)F-FLT and followed for at least 2 y after the initial imaging work-up. Uptake was assessed at a lesion level, visually and quantitatively by maximum standardized uptake values (SUVmax) for both tracers. (18)F-FLT uptake was compared with risk factors known to be linked with a poor prognosis in PGLs (SDHB-mutated status, lesion size, dopaminergic phenotype) and with (18)F-FDG uptake.

RESULTS

In 12 patients, 77 lesions were assessed. All lesions had low (18)F-FLT uptake (median SUVmax, 2.25; range, 0.7-4.5). There was no apparent superiority of (18)F-FLT uptake in progressive lesions, and most of the lesions showed a mismatch, with high (18)F-FDG uptake (median SUVmax, 10.8; range, 1.1-79.0) contrasting with low (18)F-FLT uptake.

CONCLUSION

This study suggests that PHEOs/PGLs-even those that progress-do not exhibit intense (18)F-FLT uptake. It provides the first in vivo demonstration that proliferation may not be a major determinant of (18)F-FDG uptake in these tumors. These findings provide new insight into the biologic behavior of PGL and suggest that antiproliferative agents may be suboptimal for treatment of these tumors.

Relationship Between 18F-FDG Uptake on PET and Recurrence Patterns After Curative Surgical Resection in Patients with Advanced Gastric Cancer

This study evaluated the predictive value of 18F-FDG PET for distant metastasis-free survival and peritoneal recurrence-free survival as well as recurrence-free survival and overall survival after curative surgical resection in patients with advanced gastric cancer (AGC).

METHODS

Two hundred seventy-nine patients with AGC who underwent preoperative 18F-FDG PET and subsequent curative surgical resection were included. The tumor-to-normal liver uptake ratio (TLR) of cancer lesions was measured, and the prognostic significance of TLR and tumor factors for distant metastasis-free survival, peritoneal recurrence-free survival, recurrence-free survival, and overall survival was assessed.

RESULTS

The 5-y recurrence-free survival, peritoneal recurrence-free survival, distant metastasis-free survival, and overall survival rates were 46.9%, 68.5%, 76.0%, and 58.1%, respectively. Depth of tumor invasion, lymph node metastasis, lymphovascular invasion, and TLR were independent prognostic factors for both recurrence-free survival and overall survival (P<0.05). For distant metastasis-free survival, lymphovascular invasion and TLR were independent risk factors (P<0.05). In patients with a TLR of 2.0 or less, the 5-y distant metastasis-free survival rate was 95.5%; in patients with a TLR greater than 2.0, the 5-y distant metastasis-free survival rate was 68.8%. For peritoneal recurrence-free survival, TLR showed no statistical significance (P=0.7) whereas pT stage, lymph node metastasis, Lauren classification, and Bormann type were independent prognostic factors (P<0.05).

CONCLUSION

18F-FDG uptake of AGC is an independent prognostic factor for distant metastasis-free survival, recurrence-free survival, and overall survival. The possibility of distant metastasis during follow-up should be considered in patients with high 18F-FDG uptake.

Clinical significance of incidental FDG uptake in the prostate gland detected by PET/CT

The value of FDG-positron emission tomography/computed tomography (PET/CT) for detecting prostate cancer is unknown. We aimed to investigate the clinical value of incidental prostate FDG uptake on PET/CT scans. We reviewed 6128 male patients who underwent FDG-PET/CT scans and selected cases that reported hypermetabolic lesion in the prostate. The patients who have prior history of prostate carcinoma or prostate surgery were excluded from the study. We have analyzed the correlation between PET/CT findings and serum prostate-specific antigen (PSA) levels, imaging (USG), urological examinations and biopsy. Incidental 18F-FDG uptake of the prostate gland was observed in 79 patients (1.3%). While sixteen of them were excluded due to inadequate clinical data, the remaining 63 patients were included for further analysis. The patients were divided into two groups; 8 patients (12.7%) in the malignant group and 55 patients (87.3%) in the benign group. The SUVmax values were not significantly different between the two groups. In 6 (75%) patients with prostate cancer, FDG uptake was observed focally in the peripheral zone of the prostate glands. There was no significant correlation between the SUVmax and the PSA levels. Incidental 18F-FDG uptake in the prostate gland is a rare condition, but a substantial portion of it is associated with the cancer. Benign and malignant lesions of the prostate gland in FDG-PET/CT imaging could not be reliably distinguished. The peripheral focally FDG uptake of prostate glands should be further examined with the clinical and labaratory evaluations.