18F-FDG PET-CT versus MRI for detection of skeletal metastasis in Ewing sarcoma.

OBJECTIVE: To determine the level of discrepancy between magnetic resonance imaging (MRI) and 18F-FDG PET-CT in detecting osseous metastases in patients with Ewing sarcoma. METHODS: Twenty patients with histopathologically confirmed Ewing sarcoma between 2000 and 2017 who underwent 18F-FDG PET-CT and MRI within a 4-week range were included. Each imaging modality was evaluated by a separate observer. Reference diagnosis of each lesion was based on histopathology or consensus of an expert panel using all available data, including at least 6 months' follow-up. Sensitivity, specificity, and predictive values were determined. Osseous lesions were analyzed on a patient and a lesion basis. Factors possibly related to false-negative findings were evaluated using Pearson's Chi-squared or Fisher's exact test. RESULTS: A total of 112 osseous lesions were diagnosed in 13 patients, 107 malignant and 5 benign. Seven patients showed no metastases on either 18F-FDG PET-CT or MRI. Forty-one skeletal metastases (39%) detected with MRI did not show increased 18F-FDG uptake on 18F-FDG PET-CT (false-negative). Lesion-based sensitivities and specificities were 62% (95%CI 52-71%) and 100% (48-100%) for 18F-FDG PET-CT; and 99% (97-100%) and 100% (48-100%) for MRI respectively. Bone lesions were more likely to be false-negative on 18F-FDG PET-CT if hematopoietic bone marrow extension was widespread and active (p = 0.001), during or after (neo)-adjuvant treatment (p = 0.001) or when the lesion was smaller than 10 mm (p < 0.001). CONCLUSION: Although no definite conclusions can be drawn from this small retrospective study, it shows that caution is needed when using 18F-FDG PET-CT for diagnosing skeletal metastases in Ewing sarcoma. Poor contrast between metastases and active hematopoietic bone marrow, chemotherapeutic treatment, and/or small size significantly decrease the diagnostic yield of 18F-FDG PET-CT, but not of MRI.

Chronic temporomandibular joint pain: two cases of osteoid osteoma and a review of the literature.

Osteoid osteoma is a benign bone tumour with self-limiting growth potential occurring in any part of the body. Two rare cases of a pathologically proven osteoid osteoma invading the temporomandibular joint (TMJ) are reported herein. This article also reviews the cases of osteoid osteoma of the craniofacial complex reported in the English-language literature to date. Although the clinical presentation of osteoid osteoma in the jaw differs from that of osteoid osteoma in the more common locations, the radiographic features are similar. In both cases presented, computed tomography revealed a small round osseous lesion with sharp margins in the TMJ. Bone scintigraphy was performed in order to differentiate the lesions from other osseous lesions. Both patients underwent surgical excision of the lesion with immediate relief of the pain. The importance of early recognition of the clinical and imaging characteristics of an osteoid osteoma of the TMJ is emphasized, in order to prevent misdiagnosis and avoid discouraging therapies.

Cost-effectiveness of FDG-PET/CT for cytologically indeterminate thyroid nodules: a decision analytic approach.

CONTEXT: Patients with thyroid nodules of indeterminate cytology undergo diagnostic surgery according to current guidelines. In 75% of patients, the nodule is benign. In these patients, surgery was unnecessary and unbeneficial because complications may occur. Preoperative fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) was found to have a very high negative predictive value (96%) and might therefore avoid futile surgery, complications, and costs. In the United States, two molecular tests of cytology material are routinely used for this purpose. OBJECTIVE: Five-year cost-effectiveness for routine implementation of FDG-PET/CT was evaluated in adult patients with indeterminate fine-needle aspiration cytology and compared with surgery in all patients and both molecular tests. DESIGN: A Markov decision model was developed to synthesize the evidence on cost-effectiveness about the four alternative strategies. The model was probabilistically analyzed. One-way sensitivity analyses of deterministic input variables likely to influence outcome were performed. SETTING AND SUBJECTS: The model was representative for adult patients with cytologically indeterminate thyroid nodules. MAIN OUTCOME MEASURES: The discounted incremental net monetary benefit (iNMB), the efficiency decision rule containing outcomes as quality-adjusted life-years and (direct) medical cost, of implementation of FDG-PET/CT is displayed. RESULTS: Full implementation of FDG-PET/CT resulted in 40% surgery for benign nodules, compared with 75% in the conventional approach, without a difference in recurrence free and overall survival. The FDG-PET/CT modality is the more efficient technology, with a mean iNMB of €3684 compared with surgery in all. Also, compared with a gene expression classifier test and a molecular marker panel, the mean iNMB of FDG-PET/CT was €1030 and €3851, respectively, and consequently the more efficient alternative. CONCLUSION: Full implementation of preoperative FDG-PET/CT in patients with indeterminate thyroid nodules could prevent up to 47% of current unnecessary surgery leading to lower costs and a modest increase of health-related quality of life. Compared with an approach with diagnostic surgery in all patients and both molecular tests, it is the least expensive alternative with similar effectiveness as the gene-expression classifier.

Comparison of two region of interest definition methods for metabolic response evaluation with [18F]FDG-PET.

AIM: In therapy response monitoring by [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), different tumor delineations are used, resulting in different values for change in glucose metabolic rate (DMRglu). We propose a technique to compare metabolic rates in a region of interest (ROI) based on fixed volumes rather than on fixed thresholds. This method involves change in lesion size. METHODS: In 49 patients with colorectal carcinoma (CRC) and 50 patients with non-small cell lung carcinoma (NSCLC) scheduled for chemotherapy, FDG-PET was performed at baseline and during chemotherapy. A ROIfixed thresholds was determined by using a 50% threshold on both baseline and follow-up FDG-PET. A ROIfixed volumes was determined by using a 50% threshold, determined on the series with the largest tumor volume. This ROIfixed volumes is used on consecutive scans. Predictive effects of both methods were investigated by survival analysis for overall and progression free survival. RESULTS: In CRC, only ROIfixed volumes based DMRglu showed significant predictive ability. In NSCLC, both techniques showed significant predictive ability. During multivariate analysis, ROIfixed volumes determined DMRglu was an independent predictor for both overall and progression free survival in NSCLC whereas ROIfixed thresholds determined MRglu was not. After dichotomization at the median DMRglu, median survival ratio was higher in ROIfixed volumes than ROIfixed thresholds for CRC (overall survival: 1.78 vs 1.25, progression free survival: 1.57 vs 1.21) and NSCLC (overall survival: 2.01 vs 2.01, progression free survival: 2.93 vs 2.13). CONCLUSION: ROIfixed volumes based DMRglu shows better correlation with survival than DMRglu determined from a ROIfixed thresholds.

Comparison of two region of interest definition methods for metabolic response evaluation with [¹8F]FDG-PET.

AIM: In therapy response monitoring by [¹8F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), different tumor delineations are used, resulting in different values for change in glucose metabolic rate (ΔMR(glu)). We propose a technique to compare metabolic rates in a region of interest (ROI) based on fixed volumes rather than on fixed thresholds. This method involves change in lesion size. METHODS: In 49 patients with colorectal carcinoma (CRC) and 50 patients with non-small cell lung carcinoma (NSCLC) scheduled for chemotherapy, FDG-PET was performed at baseline and during chemotherapy. A ROI(fixed thresholds) was determined by using a 50% threshold on both baseline and follow-up FDG-PET. A ROI(fixed volumes) was determined by using a 50% threshold, determined on the series with the largest tumor volume. This ROI(fixed volumes) is used on consecutive scans. Predictive effects of both methods were investigated by survival analysis for overall and progression free survival. RESULTS: In CRC, only ROI(fixed volumes) based ΔMR(glu) showed significant predictive ability. In NSCLC, both techniques showed significant predictive ability. During multivariate analysis, ROI(fixed volumes) determined ΔMR(glu) was an independent predictor for both overall and progression free survival in NSCLC whereas ROI(fixed thresholds) determined MRglu was not. After dichotomization at the median ΔMR(glu), median survival ratio was higher in ROI(fixed volumes) than ROI(fixed thresholds) for CRC (overall survival: 1.78 vs 1.25, progression free survival: 1.57 vs 1.21) and NSCLC (overall survival: 2.01 vs 2.01, progression free survival: 2.93 vs 2.13). CONCLUSION: ROI(fixed volumes) based ΔMR(glu) shows better correlation with survival than ΔMR(glu) determined from a ROI(fixed thresholds).

Tailoring therapy in colorectal cancer by PET-CT.

Positron emission tomography (PET) using [(18)F]-fluoro-2'-deoxy-D-glucose (FDG) has an added value in the clinical management of patients with colorectal carcinoma (CRC). This includes restaging patients before surgical resection or local recurrence of liver metastases, assessment whether residual lesions are scar or recurrence and in pinpointing recurrence in case of unexplained increase in serum levels of carcinoembryonic antigen. At present, there is an increasing interest in new roles for FDG-PET, especially for characterization of lesions, for prognosis and response prediction and for early evaluation of treatment response to commenced therapy. FDG-PET may lead to better selection of patients for different therapeutic options or to early individual adjustment of current treatment. This systematic review aims to provide an up-to-date overview of literature on the current and potential value of FDG-PET in CRC patients by addressing staging and recurrence detection, prognosis and response prediction and evaluation of preoperative (chemo)radiotherapy for primary rectal carcinoma, ablative treatment for unresectable liver metastases and chemotherapy for advanced CRC.