Vilma Derbekyan

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

PurposeThe 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.MethodsWe 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.ResultsSufficient 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.ConclusionThe 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.

Hemodynamic effects of encainide in patients with ventricular arrhythmia and poor ventricular function

Gated cardiac scanning was used to evaluate the hemodynamic effects of encainide in 19 patients (1 woman) with complex ventricular arrhythmia and depressed left ventricular (LV) function (ejection fraction less than 45%). Patients were 36 to 80 years old (average 61). All were candidates for long-term encainide therapy after having failed with currently available antiarrhythmics. Sixty-three percent had congestive heart failure before they received encainide. All were evaluated in the hospital before encainide therapy by a gated cardiac scan performed at least 3 days after discontinuing all antiarrhythmic drugs. Patients received oral encainide in doses of 75 to 200 mg. Gated cardiac scans were repeated 1 to 2 weeks later when an 80% reduction in frequency of premature ventricular complexes was observed on a 24-hour Holter recording. No patient had worsening of congestive heart failure during encainide therapy. Encainide did not significantly affect ejection fraction, which averaged 22 +/- 10% before and 25 +/- 14% (SD) after encainide (difference not significant [NS]). Other hemodynamic variables, including heart rate, blood pressure, stroke volume and end-diastolic volume, remained unchanged during encainide therapy. Digoxin blood levels in 10 patients averaged 1.04 +/- 0.43 before and 1.22 +/- 0.47 mg/ml (NS) during encainide therapy. Thus, encainide given orally in clinically effective doses does not appear to have significant hemodynamic effects in patients with ventricular arrhythmia and depressed LV function.

Myeloid sarcoma presenting as an anterior mediastinal mass invading the pericardium: Serial Imaging With F-18 FDG PET/CT.

Myeloid sarcoma is a tumor formed by extramedullary accumulation of myeloblasts or immature myeloid cells. These tumors can develop in lymphoid organs, bone, skin, soft tissue, and other organs, and may precede or occur concurrently with acute myeloid leukemia. This is a case of a 42-year-old man who presented with a 2-week history of cough and shortness of breath on exertion. A computed tomography (CT) scan showed a large mediastinal mass and pericardial effusion. An F-18 fluorodeoxyglucose positron emission tomography-CT scan showed intense fluorodeoxyglucose (FDG) uptake in the mediastinal mass with invasion of the parietal pericardium. Biopsy of the mediastinal mass and pericardium revealed myeloid sarcoma. The pericardial effusion was drained and the patient was treated with high-dose cytosine arabinoside (HiDAC) chemotherapy. A follow-up positron emission tomography-CT was done 2 months after the last cycle, showing poor response to therapy and significant progression of disease with invasion through the anterior chest wall. Myeloid sarcoma can be added to the differential diagnosis of F-18 FDG avid anterior mediastinal masses, as well as F-18 FDG uptake in the pericardium.

Early diagnosis of myositis ossificans with Tc-99m diphosphonate imaging

Myositis ossificans is primarily a disorder of young adults, whereby an area of muscle mass undergoes progressive ossification. The authors review a case in which the patients presentation was somewhat atypical, and where the course of disease was unusually prolonged. Examination of the soft tissue lesion using Tc-99m diphosphonate bone scans was helpful in establishing the diagnosis and in determining the full extent of the process early in its evolution.

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.

Tc-99m red blood cell venography in deep venous thrombosis of the lower limb. An overview

Tc-99m red blood cell venography is a simple and sensitive technique for the diagnosis of deep vein thrombosis of the lower limb. The static high count blood pool images of the deep venous system of the leg are readily interpretable and show good correlation with contrast venography. The advantages and limitations of this technique in the clinical setting are discussed in detail in this review.

The relationship between central venous pressure and pulmonary capillary wedge pressure during aortic surgery

Twenty-three ASA physical status II-III patients scheduled for elective abdominal aortic surgery were studied preoperatively with multiple unit gated acquisition angiography (MUGA) scan to determine the resting left ventricular and right ventricular ejection fractions (LVEF and RVEF respectively). lntraoperatively pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) were measured in each patient at five different time periods in the horizontal, 24° head up, and 24° head down table tilt positions. The correlation between absolute values and changes in PCWP and CVP, and the degree to which preoperative knowledge of LVEF and RVEF predicted these correlations were examined. Resting LVEF ranged from 0.1 to 0.84. Thirteen of the 23 patients failed to show significant correlation (p < 0.05) between the absolute values of PCWP and CVP either before and/or after aortic crossclamp. When the correlation coefficients from this analysis were ranked against LVEF, there was a weak but significant correlation before aortic crossclamp (r = 0.41), but not after. The correlation between a change in PCWP and a change in CVP was significant for the 23 patients at all lime intervals, before and after aortic crossclamp. However, the prediction of a change of PCWP value from a known change of CVP value ranged in accuracy from ± 3 mmHg to ± 12.5 mmHg. The study suggests that if the filling pressures of both ventricles need to be assessed during aortic surgery, then the PCWP and CVP must be independently measured. Preoperative knowledge of LVEF and RVEF as determined by MUGA scan did not identify a subgroup of patients in whom PCWP and CVP correlated consistently throughout aortic surgery.RésuméNous avons mesuré la fraction ďéjection des ventricules droit et gauche, par ventriculographie isotopique, chez 23 patients de classe ASA I et II, devant subir une chirurgie de ľaorte abdominale. Durant ľopération, nous avons pris la tension veineuse centrale (TVC) et la pression ďocclusion de ľartère pulmonaire (POAP) chez tous les patients, à cinq moments différents, et ce en position horizontale, en trendelenbourg (24°) et en anti-trendelenbourg (24°). Nous avons cherché une corrélation entre les valeurs absolues de la TVC et de la POAP et leurs fluctuations respectives. On a tenté de prédire des corrélations à la lumière desfractions ďéjection ventriculaires. Les valeurs de fraction ďéjection du ventricule gauche, au repos, s’étendaient de 0.1 à 0.85. On n’a pas trouvé de corrélation (p < 0.05) chez 13 des 23 patients, entre les valeurs absolues de la POAP et de la TVC et ce avant, durant et après le clampage aortique. Nous avons identifié une corrélation entre les fluctuations du wedge et de la TVC chez les 23 patients, à tous les intervalles étudiés avant et aprés le clampage aortique. Les différences entre les valeurs mesurées de TVC et les valeurs prédites de POAP s’étendaient de ± 3 à 12.5 mmHg. Cette étude suggère que si les pressions de remplissage des deux ventricules doivent être evaluées au cours de la chirurgie de ľaorte, la tension veineuse et la tension pulmonaire de capillaire bloquée “wedge” doivent faire ľobjet de mesure indépendante. De plus la connaissance des fractions ďéjection ventriculaires, avant ľopération, n’a pas permis ďidentifier un sous groupe de patients chez qui on pouvait prédire de façon exacte la corrélation entre la TVC et la POAP.

Spectrum of Malignant Pleural and Pericardial Disease on FDG PET/CT

OBJECTIVE The purpose of this article is to illustrate a wide spectrum of malignant primary and secondary pleural and pericardial diseases imaged with (18)F-FDG PET/CT. CONCLUSION A wide variety of malignant pleural and pericardial diseases can be detected, staged, and monitored by FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas is to show that the spectrum of pleural and pericardial disease that can be evaluated with PET/CT is much broader than current literature would suggest. PET/CT readers and oncologists should be aware of the wide variety of malignancies that can affect the pleura and pericardium and some of the patterns of FDG uptake that can be observed in these cases.

Improvement in Resting Ventricular Performance Following Coronary Bypass Surgery

To assess the changes in resting left ventricular (LV) function following coronary bypass surgery, technetium 99m-labeled multiple equilibrated blood pool gated scans were performed in 53 consecutive patients at rest, before operation, and at 24 hours and 1 week after operation. Left ventricular ejection fraction (LVEF) and end-diastolic volume (EDV) were measured. The LVEF increased significantly from a preoperative value of 49 +/- 2% to 56 +/- 2% at 24 hours after operation (p less than 0.05) and 56 +/- 2% at 1 week following operation (p less than 0.05 compared with the preoperative value). The EDV also exhibited significant changes, decreasing from a preoperative value of 148 +/- 8 ml to 91 +/- 11 ml at 24 hours (p less than 0.001) and 114 +/- 9 ml at 1 week (p less than 0.01 compared with the preoperative value). When the patients were divided into two groups according to the preoperative LVEF (Group 1, LVEF of greater than or equal to 50%; Group 2, LVEF of less than 50%), the observed changes were similar. This study demonstrates significant improvement in resting LV function 24 hours following coronary bypass surgery. This improvement persists at 1 week and is not related to the degree of preoperative impairment. We conclude that the combination of successful revascularization and optimal myocardial protection can result in significant improvement of LV function at rest.

Angiomatoid fibrous histiocytoma: staging and evaluation of response to therapy with F-18 FDG PET/CT.

Angiomatoid fibrous histiocytoma is a very rare tumor that accounts for 0.3% of all soft-tissue tumors, and occurs predominantly in the extremities of adolescents and young adults. It has been classified by the World Health Organization as a tumor of uncertain differentiation with intermediate malignant potential, although recent evidence suggests a myoid or myofibroblastic cell origin. Most examples behave in an indolent manner with a regional recurrence rate of 15% and a rate of metastasis of 1%. We present a 29-year-old woman who was referred for an F-18 FDG PET/CT to evaluate a left shoulder mass. She had multiple local FDG-avid lymph nodes, and initial biopsy was suggestive of epithelioid sarcoma. She was treated with chemotherapy, but a post-therapy PET/CT showed minimal response and radical surgical excision was performed. The histopathology and immunohistochemistry was consistent with angiomatoid fibrous histiocytoma. This case highlights a potential new utility for F-18 FDG PET/CT in the staging and evaluation of response to therapy for this very rare soft-tissue tumor.