F-18 FDG PET/CT Imaging in Normal Variants, Pitfalls and Artifacts in the Abdomen and Pelvis

Since its introduction into clinical practice, multimodality imaging has revolutionized diagnostic imaging for both oncologic and non-oncologic pathologies. 18F-fluorodeoxyglucose (18F-FDG) PET/CT imaging which takes advantage of increased anaerobic glycolysis that occurs in tumor cells (Warburg effect) has gained significant clinical relevance in the management of most, if not all oncologic conditions. Because FDG is taken by both normal and abnormal tissues, PET/CT imaging may demonstrate several normal variants and imaging pitfalls. These may ultimately impact disease detection and diagnostic accuracy. Imaging specialists (nuclear medicine physicians and radiologists) must demonstrate a thorough understanding of normal and physiologic variants in the distribution of 18F-FDG; including potential imaging pitfalls and technical artifacts to minimize misinterpretation of images. The normal physiologic course of 18F-FDG results in a variable degree of uptake in the stomach, liver, spleen, small and large bowel. Urinary excretion results in renal, ureteric, and urinary bladder uptake. Technical artifacts can occur due to motion, truncation as well as the effects of contrast agents and metallic hardware. Using pictorial illustrations, this paper aims to describe the variants of physiologic 18F-FDG uptake that may mimic pathology as well as potential benign conditions that may result in misinterpretation of PET/CT images in common oncologic conditions of the abdomen and pelvis.

Intravascular leiomyomatosis with cardiac extension: a case report

Background Intravascular leiomyomatosis with intracardiac extension is a rare benign tumor seen exclusively in women, characterized by proliferation of uterine smooth muscle cells through the venous circulation into the inferior vena cava and the right heart chambers. Case summary A 47 years old women with history of previous hysterectomy due to myomatosis, presented with nausea, anorexia and bilateral lower limb swelling over the preceding two months. An outpatient abdominal ultrasound discovered a mass in the Inferior vena cava. Echocardiogram and Computed tomography demonstrated a large intravascular mass extending from the pelvis to the right heart chambers. The tumor was completely removed in a concomitant open-heart surgery and laparotomy. Post operative course was uncomplicated. A month later the patient was feeling well and in good clinical condition. The histological analysis consisted with intravascular leiomyomatosis. Discussion Intracardiac leiomyomatosis is a rare clinical condition which requires high index of suspicion. Multimodality imaging is usually required to establish the preoperative diagnosis, although the final diagnosis is achieved with tissue investigation. Complete surgical resection of the tumor is curative and associated with good long-term prognosis.

Systemic Artery to Pulmonary Artery Shunt Mimicking Acute Pulmonary Embolism, Unmasked by a Multimodality Imaging Approach

In this report, we describe the functional imaging findings of systemic artery to pulmonary artery shunt in V/Q SPECT CT imaging. A 63-year-old man with small-cell lung cancer underwent CT pulmonary angiography (CTPA) for suspected acute pulmonary embolism (PE). The CTPA showed an isolated segmental filling defect in the right lower lobe, which was initially interpreted as positive for PE but was actually the consequence of a systemic artery to pulmonary artery shunt due to the recruitment of the bronchial arterial network by the adjacent tumor. A V/Q SPECT/CT scan was also performed, demonstrating a matched perfusion/ventilation defect in the right lower lobe.

Multimodality Imaging Assessment of Anomalous Aortic Origin of the Left Main Coronary Artery Presenting With Syncope and Non-ST Elevation Myocardial Infarction

ABSTRACT Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital abnormality associated with myocardial ischemia and sudden cardiac death. We present a case of a 20 year old previously healthy male presenting with exertional syncope and non-ST elevation myocardial infarction. Coronary computed tomography angiography showed an anomalous left main coronary artery arising from the right coronary cusp with a slit-like appearance, acute angle origin, intramural course, and a subsequent inter-arterial course between the main pulmonary artery and the proximal aorta. Cardiac magnetic resonance imaging demonstrated myocardial infarction in the distribution of the left main coronary artery. The patient underwent successful surgical correction with unroofing of the left main coronary artery. He has had no syncopal episodes or recurrence of chest pain and returned to full duty status in the United States Marine Corps. This case report demonstrates the evaluation and management of a patient with AAOCA.

Purposeful use of multimodality imaging in the diagnosis of caseous mitral annular calcification: a case series report

Background Caseous mitral annular calcification (CMAC) is a rare liquefactive variant of mitral annular calcification (MAC) and superficially mimics a cardiac vegetation or abscess. CMAC is viewed as a benign condition of MAC, while MAC has clinical implications for patients’ lives. Correctly diagnosing CMAC is essential in order to avoid unnecessary interventions, cardiac surgery or even psychological suffering for the patient. Case presentation We report on 6 patients with suspected intra-cardiac masses of the mitral annulus that were referred to our institution for further clarification. A definitive diagnosis of CMAC was achieved by combining echocardiography (Echo), cardiac magnetic resonance imaging (MRI) and cardiac computed tomography (CT) for these patients. Echo assessed the mass itself and possible interactions with the mitral valve. MRI was useful in differentiating the tissue from other benign or malign neoplasms. CT revealed the typical structure of CMAC with a “soft” liquefied centre and an outer capsule with calcification. Conclusion CMAC is a rare condition, and most clinicians and even radiologists are not familiar with it. CMAC can be mistaken for an intra-cardiac tumour, thombus, vegetation, or abscess. Non-invasive multimodality imaging (i.e. Echo, MRI, and CT) helps to establish a definitive diagnosis of CMAC and avoid unnecessary interventions especially in uncertain cases.

The Role of Multimodality Imaging in Left-Sided Prosthetic Valve Dysfunction

Prosthetic valve (PV) dysfunction (PVD) is a complication of mechanical or biological PV. Etiologic mechanisms associated with PVD include fibrotic pannus ingrowth, thrombosis, structural valve degeneration, and endocarditis resulting in different grades of obstruction and/or regurgitation. PVD can be life threatening and often challenging to diagnose due to the similarities between the clinical presentations of different causes. Nevertheless, identifying the cause of PVD is critical to treatment administration (thrombolysis, surgery, or percutaneous procedure). In this report, we review the role of multimodality imaging in the diagnosis of PVD. Specifically, this review discusses the characteristics of advanced imaging modalities underlying the importance of an integrated approach including 2D/3D transthoracic and transesophageal echocardiography, fluoroscopy, and computed tomography. In this scenario, it is critical to understand the strengths and weaknesses of each modality according to the suspected cause of PVD. In conclusion, for patients with suspected or known PVD, this stepwise imaging approach may lead to a simplified, more rapid, accurate and specific workflow and management.