F-18 fluorodeoxyglucose positron emission tomographic imaging: In search of an unknown primary tumor

Epithelioid sarcoma is a rare tumor that occurs almost exclusively in the distal extremities. The primary site in this case was seen with F-18 fluorodeoxygluclose (FDG) positron emission tomography (PET). This tumor exhibits various histologic growth patterns and diverse clinical presentations, and thus the diagnosis is often delayed for months or years. They have a tendency to spread to noncontiguous areas of skin, subcutaneous tissue, fat, and bone. Many case reports have suggested a causal relation to trauma. Treatment includes wide surgical excision, often involving amputation of the extremity, and regional lymph node dissection

Accessory Findings on F-18 FDG Positron Emission Tomography in Bronchogenic Carcinoma

A 76-year-old man with proved small-cell and non-small-cell lung cancer and symptoms of a paraneoplastic syndrome, including a heliotrope rash; scaly erythematous rash over the face, neck, and upper torso; proximal muscle weakness; and creatine kinase elevation, underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) as part of a work-up to detect (mediastinal) lymph nodes or distant metastases

Standardised FDG uptake: A prognostic factor for inoperable non-small cell lung cancer

The aim of this study was to investigate the relationship between standardised uptake value (SUV) obtained from [18F]fluorodeoxyglucose positron emission tomography (FDG PET) and treatment response/survival of inoperable non-small cell lung cancer (NSCLC) patients treated with high dose radiotherapy. Fifty-one patients were included recording stage, performance, weight loss, tumour volume, histology, lymph node involvement, SUV, and delivered radiation dose. The maximum SUV (SUVmax) within the primary tumour was a sensitive and specific factor for predicting treatment response. Apart from SUVmax, stage and performance were also independent predictive factors for treatment response. In a multivariate disease-specific survival (DSS) analysis, SUVmax (P = 0.01), performance status (P = 0.008) and stage (P = 0.04) were prognostic factors. For overall survival (OS), SUVmax (P = 0.001) and performance (P = 0.06) were important prognostic factors. SUVmax was an important prognostic factor for survival of inoperable NSCLC patients and a predictive factor for treatment response. Although the number of patients was small, the treatment was not homogeneous and the use of FDG SUV may have had constraints, we still conclude that the FDG SUV is potentially a good indicator for selecting patients for different treatment strategies

Screening for distant metastases in patients with head and neck cancer: Is there a role for 18FDG-PET?

The detection of distant metastases and second primary tumours at the time of initial evaluation changes the prognosis and influences the selection of treatment modality in patients with HNSCC. Until recently chest CT was the single most effective test to screen for distant metastases in HNSCC patients. In this observational cohort study we prospectively compared the yield of whole body 18FDG-PET and chest CT to detect distant metastases and synchronous primary tumours. The results of whole body 18FDG-PET and chest CT were analysed in 34 consecutive HNSCC patients with previously established risk factors for the presence of distant metastases. Four patients were diagnosed with distant metastases or second primary tumours: CT as well as 18FDG-PET identified one patient with lung metastases and another with primary lung cancer. In addition, 18FDG-PET detected second primary tumours in two patients (hepatocellular carcinoma and abdominal adenocarcinoma). However increased uptake sites at 18FDG-PET in lung, liver and pelvis in five patients were not confirmed by other imaging modalities. The added value of whole body 18FDG-PET versus chest CT was to identify unknown malignancy in 6% of the patients. Confirmation of positive 18FDG-PET findings is feasible and necessary

Impact of lymphoscintigraphy on sentinel node identification with technetium-99m-colloidal albumin in breast cancer

Identification of the sentinel node by using colloidal tracers and a gamma probe or lymphoscintigraphy could be an effective alternative for the complicated original dye-oriented approach. We studied the sentinel node detection rate using early and delayed imaging in breast cancer patients. Methods: Thirty-seven patients were imaged 2 hr and 18 hr after peritumoral injection of 99mTc-colloidal albumin. Preoperatively, axillary loci were located with a handheld gamma probe that was also used to isolate radiolabeled nodes from the axillary dissection specimens. The predictive value of the sentinel node for the axillary tumorstatus was evaluated with histological examination. Results: Two and 18 hr after injection, lymphoscintigraphy revealed one to three separate axillary lymph nodes in 33 and 34 patients, respectively. In 30 patients the axillary foci were easily localized with the gamma probe preoperatively. In all 34 patients (92%), with visualized axillary foci, at least one radioactive sample could be retrieved using the gamma probe (total 53 samples). Metastases were found in the sentinel nodes of 11 patients, in seven of 11 being the only tumor-positive lymph node in the axilla. There were no false-negative sentinel nodes. Conclusion: The selective targeting and prolonged intranodal retention of 99mTC-colloidal albumin allows successful sentinel node identification in most (92%) patients

Cost-effectiveness of response evaluation after chemoradiation in patients with advanced oropharyngeal cancer using 18F-FDG-PET-CT and/or diffusion-weighted MRI

Background: Considerable variation exists in diagnostic tests used for local response evaluation after chemoradiation in patients with advanced oropharyngeal cancer. The yield of invasive examination under general anesthesia (EUA) with biopsies in all patients is low and it may induce substantial morbidity. We explored four response evaluation strategies to detect local residual disease in terms of diagnostic accuracy and cost-effectiveness. Methods: We built a decision-analytic model using trial data of forty-six patients and scientific literature. We estimated for four strategies the proportion of correct diagnoses, costs concerning diagnostic instruments and the proportion of unnecessary EUA indications. Besides a reference strategy, i.e. EUA for all patients, we considered three imaging strategies consisting of 18FDG-PET-CT, diffusion-weighted MRI (DW-MRI), or both 18FDG-PET-CT and DW-MRI followed by EUA after a positive test. The impact of uncertainty was assessed in sensitivity analyses. Results: The EUA strategy led to 96% correct diagnoses. Expected costs were €468 per patient whereas 89% of EUA indications were unnecessary. The DW-MRI strategy was the least costly strategy, but also led to the lowest proportion of correct diagnoses, i.e. 93%. The PET-CT strategy and combined imaging strategy were dominated by the EUA strategy due to respectively a smaller or equal proportion of correct diagnoses, at higher costs. However, the combination of PET-CT and DW-MRI had the highest sensitivity. All imaging strategies considerably reduced (unnecessary) EUA indications and its associated burden compared to the EUA strategy. Conclusions: Because the combined PET-CT and DW-MRI strategy costs only an additional €927 per patient, it is preferred over immediate EUA since it reaches the same diagnostic accuracy in detecting local residual disease while leading to substantially less unnecessary EUA indications. However, if healthcare resources are limited, DW-MRI is the strategy of choice because of lower costs while still providing a large reduction in unnecessary EUA indications

Initial experience with a prototype dual-crystal (LSO/NaI) dual-head coincidence camera in oncology

The aim of this study was to evaluate the in vivo performance of a prototype dual-crystal [lutetium oxyorthosilicate (LSO)/sodium iodide (NaI)] dual-head coincidence camera (DHC) for PET and SPET (LSO-PS), in comparison to BGO-PET with fluorine-18 fluorodeoxyglucose (FDG) in oncology. This follows earlier reports that LSO-PS has noise-equivalent counting (NEC) rates comparable to partial ring BGO-PET, i.e. clearly higher than standard NaI DHCs. Twenty-four randomly selected oncological patients referred for whole-body FDG-PET underwent BGO-PET followed by LSO-PS. Four nuclear medicine physicians were randomised to read a single scan modality, in terms of lesion intensity, location and likelihood of malignancy. BGO-PET was considered the gold standard. Forty-eight lesions were classified as positive with BGO-PET, of which LSO-PS identified 73% (95% CI 60-86%). There was good observer agreement for both modalities in terms of intensity, location and interpretation. Lesions were missed by LSO-PS in 13 patients in the chest (n=6), neck (n=3) and abdomen (n=4). The diameter of these lesions was estimated to be 0.5-1 cm. Initial results justify further evaluation of LSO-PS in specific clinical situations, especially if a role as an instrument of triage for PET is foreseen

Biologic correlates of 18fluorodeoxyglucose uptake in human breast cancer measured by positron emission tomography

Purpose: Variable uptake of the glucose analog 18fluoradeoxyglucose (FDG) has been noticed in positron emission tomography (PET) studies of breast cancer patients, with low uptake occurring especially in lobular cancer. At present, no satisfactory biologic explanation exists for this phenomenon. This study compared 18FDG uptake in vivo with biomarkers expected to be involved in the underlying biologic mechanisms. Patients and Methods: Preoperative 18FDG-PET scans were performed in 55 patients. 18FDG activity was assessed visually by three observers using a four-point score. Tumor sections were stained by immunohistochemistry for glucose transporter-1 (Glut-1); Hexokinase (HK) I, II, and III; macrophages; hypoxia-inducible factor-1-alfa (HIF-1α); vascular endothelial growth factor a(VEGF165); and microvessels. Mitotic activity index (MAI), amount of necrosis, number of lymphocytes, and tumor cells/volume were assessed. Results: There were positive correlations between 18FDG uptake and Glut-1 expression (P < .001), MAI (P = .001), amount of necrosis (P = .010), number of tumor cells/volume (P = .009), expression of HK I (P = .019), number of lymphocytes (P = .032), and microvessel density (r = .373; P = .005). HIF-1α, VEGF165, HK II, HK III, and macrophages showed no univariate correlation with 18FDG. In logistic regression, however, HIF-I α and HK II added value to MAI and Glut- 1. Conclusion: 18FDG uptake in breast cancer is a function of microvasculature for delivering nutrients, Glut-1 for transportation of 18FDG into the cell, HK for entering 18FDG into glycolysis, number of tumor cells/volume, proliferation rate (also reflected in necrosis), number of lymphocytes (not macrophages), and HIF-1 α for upregulating Glut-1. Together, these features explain why breast cancers vary in 18FDG uptake and elucidate the low uptake in lobular breast cancer