F-18 FDG Uptake in Bilateral Pulmonary Artery Leiomyosarcomata, One Mimicking a Pulmonary Embolus

Dual-energy CT-based iodine quantification for differentiating pulmonary artery sarcoma from pulmonary thromboembolism: a pilot study

OBJECTIVES

The purpose of this study was to determine whether dual-energy computed tomography (DECT) angiography could differentiate pulmonary thromboembolism (PTE) from pulmonary artery sarcoma (PAS).

METHODS

We prospectively enrolled 19 patients that had a filling defect in the main pulmonary artery on DECT. Six patients who had PAS and underwent DECT were retrospectively enrolled for comparison. Pathological results or follow-up CT after anticoagulation therapy were used to make the final diagnosis. Two investigators measured the following parameters at the filling defect in the main pulmonary artery: CT attenuation density [Hounsfield units (HU)], iodine-related HU (IHU) and iodine concentration (IC, mg/ml).

RESULTS

From a total of 25 patients (M:F = 10:15; mean age, 65 years old), 19 were categorised into the PTE group and six were categorised into the PAS group. The mean HU values were not significantly different between the PTE and PAS groups (45.5 ± 15.9 vs 47.1 ± 9.2 HU; P = 0.776). However, the mean IHU and IC values of the lesions were significantly different between the PTE and PAS groups (10.6 ± 7.2 vs 27.9 ± 9.1 HU; P = 0.004, and 0.61 ± 0.39 vs 1.49 ± 0.57; P = 0.001).

CONCLUSIONS

DECT angiography using a quantitative analytic methodology can be used to differentiate PTE and PAS.

KEY POINTS

• DECT can be useful for differentiation of PAS and PTE. • With quantitative analysis, DECT offers tissue characterisation by detecting lesion parameter increases. • The patients without predisposing factors for PTE can be candidates for DECT.

Treatment of a recurrent pulmonary artery leiomyosarcoma with a combination of surgery, chemotherapy, and radiotherapy: A case report and literature review

Pulmonary artery (PA) leiomyosarcoma (PAL) is a rare but extremely malignant tumor of the cardiovascular system, which is often misdiagnosed as pulmonary thromboembolism. Although the early detection and surgical resection improves patient survival, the benefits of adjuvant therapy are not well understood. The current study presents the case of a patient with primary PAL who underwent surgical resection along with three courses of chemotherapy. Despite these interventions, the patient experienced recurrence of the PAL within four months following treatment. The patient received localized radiotherapy and subsequently achieved a stable disease state. This case indicates that radiotherapy may offer a benefit to PAL patients, particularly those who do not respond to chemotherapy.

18F-fluorodeoxyglucose positron emission tomography as a noninvasive method for the diagnosis of primary pulmonary artery sarcoma

Pulmonary artery sarcomas are rare, difficult-to-diagnose tumors that frequently mimic chronic pulmonary thromboembolism. We report the cases of two female patients with clinical signs of dyspnea and lung masses associated with pulmonary artery filling defects on chest CT angiography. We performed 18F-fluorodeoxyglucose positron emission tomography, which revealed increased radiotracer uptake in those lesions. Pulmonary artery sarcoma was subsequently confirmed by anatomopathological examination. We emphasize the importance of this type of tomography as a noninvasive method for the diagnosis of these tumors.

Pulmonary artery sarcoma detected on F-18 FDG PET/CT as origin of multiple spinal metastases

A 67-year-old man with back pain was diagnosed as having multiple spinal metastases on MRI. On CT scan, only a filling defect in the right pulmonary artery was observed and suspected as venous thromboembolism. On F-18 fluorodeoxyglucose (FDG) PET/CT, intense hypermetabolism was observed in the right pulmonary artery in addition to the metastatic spine lesions. Biopsy confirmed the lesion as a primary pulmonary artery sarcoma (PAS), and the spine lesions as metastases of PAS. Although PAS is rare and its bone metastasis presenting initial symptom is extremely rare, FDG PET/CT is an effective diagnostic modality for PAS, not only in discrimination from venous thromboembolism, but also in workup of metastatic origin.

Usefulness of F-18 fluorodeoxyglucose positron emission tomography/computed tomography in a case of choriocarcinoma presenting as pulmonary embolism

This case demonstrates the utility of performing F-18 fluorodeoxyglucose positron emission tomography/computed tomography for the investigation of an unresolving pulmonary embolus, where early diagnosis of tumor thrombus or primary neoplastic conditions of the pulmonary artery may be made. Choriocarcinoma presenting within the pulmonary artery is rare although a literature review shows that a number of important differential diagnoses of hypermetabolic pulmonary lesions should be kept in mind.

Role of modern imaging techniques for diagnosis of infection in the era of 18F-fluorodeoxyglucose positron emission tomography

During the past several years, it has become quite evident that positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) imaging can play a major role in the management of patients with suspected infection. Particularly, several groups have demonstrated that this powerful imaging methodology is very effective in the evaluation of osteomyelitis, infected prostheses, fever of unknown origin, and AIDS. In view of its extraordinary sensitivity in detecting disease activity and the ability to quantitate the degree of FDG uptake, PET might prove to be an appropriate modality for monitoring disease activity and evaluating response to therapy. FDG-PET has many advantages over existing imaging techniques for the diagnosis of infectious diseases. These include feasibility of securing diagnostic results within 1.5 to 2 h, excellent spatial resolution, and accurate anatomical localization of sites of abnormality. The availability of PET/computed tomography as a practical tool has further enhanced the role of metabolic imaging in many settings. In the future, this modality is very likely to be employed on a routine basis for detecting, characterizing, and monitoring patients with suspected and proven infection.

Pulmonary artery sarcoma masquerading as saddle pulmonary embolism

Pulmonary artery sarcoma is a highly malignant tumour. Therefore, making the diagnosis is very important. We describe a case which presented with dyspnea on exertion and was initially diagnosed as saddle pulmonary embolism per CT thorax with contrast. Despite adequate anticoagulation, symptoms still progressed. Follow-up CT thorax showed an extension of the presumed filling defect or clots into the left main pulmonary artery with new lung nodules. This prompted suspicion that this may not be a pulmonary embolism. Biopsy of the lung nodule revealed high grade soft tissue sarcoma with primary source from the pulmonary artery. Our case highlights that pulmonary artery sarcoma should always be included in the differential diagnosis of pulmonary embolism especially, if symptoms still progress while on adequate anticoagulation, or any pulmonary nodules develop on follow-up exam.