Malignant peripheral nerve sheath tumours of the pericardium in a patient with Neurofibromatosis type 1: The diagnostic value of 18F-FDG PET-CT and I-123 MIBG SPECT-CT.

A 25 year old female with known neurofibromatosis type 1 with a large anterior mediastinal mass was investigated. F18-FDG PET-CT revealed a radiotracer avid anterior mediastinal mass with SUVmax of 4.3 and demonstrating a hypoactive center. The Iodine-123 MIBG SPECT-CT study performed subsequently did not demonstrate any uptake, thereby excluding for the most part the diagnoses of paraganglioma or neuroblastoma. At final pathology, a malignant peripheral nerve sheath tumour (MPNST) of the pericardium with areas of chondrosarcomatous and angiosarcomatous differentiation was diagnosed.

Detection of Intrathoracic Bleeding by 99mTc-Labeled Red Blood Cell SPECT/CT After Wedge Biopsy of Pulmonary Angiosarcoma.

A 52-y-old man presenting with dyspnea and a massive effusion in the right pleural cavity underwent wedge biopsies of pulmonary lesions found on thoracic CT, leading to a diagnosis of pleural angiosarcoma. Bleeding developed postoperatively and was investigated using pulmonary CT angiography, which failed to identify a site of active bleeding. (99m)Tc-labeled red blood cell (RBC) SPECT/CT of the chest was performed, and the site was rapidly located. To our knowledge, this is the first case reported in the literature of localization of intrathoracic bleeding using (99m)Tc-RBC SPECT/CT.

The relative value of 18F-FDG PET interpretation criteria in generating a probabilistic approach for characterization of pulmonary nodules.

PURPOSE: The evaluation of pulmonary nodules constitutes a large part of PET-CT studies. In this study, we aimed to evaluate the different interpretation criteria in F-fluorodeoxyglucose PET attenuation-corrected and non-attenuation-corrected studies as individual predictors of malignancy in order to propose a useful combination of criteria that can be used in daily practice to classify nodules appropriately. PATIENTS AND METHODS: We performed a historical prospective survey of all consecutive patients referred to our service for the initial assessment of pulmonary nodules and sought the final characterization of these nodules either from tissue sampling or from radiological and clinical follow-up. RESULTS: A total of 104 nodules from 82 patients were included, with a prevalence of malignancy of 53%. Absence of uptake on non-attenuation-corrected studies was found to be the best predictive criterion for benignancy, with a negative predictive value of 97%, and the highest relative risk for malignancy, with a value of 20.9. Uptake higher than that of the mediastinum on attenuation-corrected images was found to be the best criterion for predicting malignancy, with a positive predictive value of 89% and a sensitivity of 73%, which is slightly better than the use of a maximal standardized uptake value cutoff of 3.0. By combining our best negative and positive criteria, we were able to classify 71% (74/104) of the lung nodules with a high level of confidence. More specifically, these two criteria allowed the correct classification of 72% (40/55) of malignant nodules and 57% (28/49) of benign nodules. The 30 remaining nodules were equally distributed in terms of malignancy and had similar characteristics on both PET and CT images. CONCLUSION: A probabilistic approach to pulmonary nodule characterization may help the reading physician to appropriately classify lung nodules into useful categories for the treating physician, moving away from nonstandardized reporting terms.

Metabolic activity measured on PET/CT correlates with clinical outcomes in patients with limb and girdle sarcomas.

OBJECTIVE: To explore the relationship between metabolic activity and outcome in patients with extremity sarcomas. METHODS: Between June 2004 and December 2011, 120 patients with newly diagnosed limb and girdle sarcomas underwent FDG-PET/CT for disease staging prior to curative intent treatment. The maximum standardized uptake value (SUV(max)) was measured for each primary tumor and correlated with outcome. Progression-free survival and overall survival (OS) were analyzed using the Kaplan-Meier method. RESULTS: Soft-tissue sarcomas were more frequent (68%) than bone (27%) or cartilage (5%) tumors. Median follow-up was 33.2 months. 51% of patients progressed during the follow-up interval and 38% died. SUV(max) was dichotomized with a cut-point of 10.3. Patients with SUV(max) < 10.3 had better DFS and OS compared with patients with SUV(max) ≥ 10.3 (P < 0.001 and P < 0.001, respectively [log-rank test]). Multivariate analysis confirmed that even after adjusting for age, sex, site, tumor type (bone vs. soft-tissue), grade, and stage; an SUV(max) ≥ 10.3 correlated with a twofold risk of progression and 2.4 times greater risk of death (hazard ratio [HR] 2.0, 95% CI, 1.1-3.7, and HR, 2.4, 95% CI, 1.1-4.9). CONCLUSION: SUV(max) is an independent adverse prognostic factor for both progression and OS in patients with extremity sarcomas.

Prognostic implication of the lymphangitic carcinomatosis pattern on perfusion lung scan.

PURPOSE: Findings not associated with thromboembolic disease on routine perfusion lung scan may sometimes have particular clinical significance. We wanted to assess the clinical importance and overall survival after the recognition of a lymphangitic carcinomatosis pattern on perfusion lung scan. CASE REPORT: We report a case of lymphangitic carcinomatosis pattern on perfusion lung scan performed in a previously healthy patient who had rapid progressive course and died the next day. METHOD: A Medline search of case reports that describes either lymphangitic carcinomatosis or tumour microemboli on perfusion lung scan. RESULTS: There were a total of 32 patients identified in 21 articles from various countries, including our case. The studied perfusion pattern was reported more often in female patients (81%) was associated with a progressive history of dyspnea (69%) and normal or mild findings on chest radiograph (58%). Of the 29 patients with available outcome data, 79% (23/29) had a progressive course after the lung scan interpretation. In 18 of these 23 cases, the actual interval of survival was given: 67% of these patients (12/18) died within the first month. DISCUSSION: A lymphangitic carcinomatosis perfusion pattern on scintigraphic imaging is associated with a poor prognosis. Nuclear medicine physicians should be aware of this association and that raising the suspicion for a metastatic process may make a difference in the treatment plan of these patients.

FDG PET/CT imaging in primary osseous and soft tissue sarcomas: a retrospective review of 212 cases.

PURPOSE: The aims of this study are to evaluate the sensitivity of FDG PET/CT for detection of soft tissue and osseous sarcomas on the basis of FDG avidity. METHODS: We retrospectively evaluated 212 consecutive patients with known soft tissue or osseous sarcoma who had undergone a FDG PET/CT study for the initial staging or assessment of recurrence of disease. The maximum standardized uptake value (SUVmax) of each primary and/or most intense metastatic lesion was measured and compared with the histological data provided in the final pathological reports. An SUVmax of 2.5 or greater was considered positive for our analysis. RESULTS: Sufficient histopathological data were available for 160 soft tissue sarcomas and 52 osseous sarcomas. FDG PET/CT detected 93.9% of all sarcomas with a sensitivity of 93.7% for soft tissue sarcomas and 94.6% for osseous sarcomas. The sensitivities of the most common sarcoma histologies were 100% for leiomyosarcomas, 94.7% for osteosarcomas, 100% for Ewing's sarcomas, 88.9% for liposarcomas, 80.0% for synovial sarcomas, 100% for gastrointestinal stromal tumors, 87.5% for malignant peripheral nerve sheath tumors, 100% for fibroblastic and myoblastic sarcomas, and 100% for malignant fibrohistiocytic tumors. The receiver-operating characteristic curve revealed an area under the curve of 94% for the discrimination of low-grade and high-grade sarcomas imaged for initial staging by FDG PET/CT. CONCLUSION: The combined metabolic and morphological information of FDG PET/CT imaging allows high sensitivity for the detection of various sarcomas and accurate discrimination between newly diagnosed low-grade and high-grade sarcomas.

Intensity of FDG uptake is not everything: synchronous liposarcoma and fibrous dysplasia in the same patient on FDG PET-CT imaging.

A growing number of studies have demonstrated the usefulness of FDG PET-CT in the preoperative assessment of soft tissue sarcomas. We report a case of a patient with a known low-grade liposarcoma demonstrating only mild hypermetabolism on a FDG PET-CT study. An incidental osseous lesion was found in the distal tibia of the same extremity during the initial workup. This tibial lesion was significantly more intense on the FDG PET-CT study than the primary sarcoma. Further investigation showed this to be an unexpected benign fibrous dysplasia. We present this case as an example of the discrepancy of FDG activity, which may exist between truly malignant and benign lesions that may arise from soft tissue and osseous structures. A benign process should remain in the differential diagnosis for hypermetabolic lesions when evaluating a case of known malignancy, especially when the degree of uptake of that lesion differs significantly from that of the primary lesion.