Cardiac and Paracardiac Masses: Complementary Role of Echocardiography and Magnetic Resonance Imaging

Cardiac CT of non-shunt pathology of the interatrial septum

The development and anatomy of the interatrial septum is complex. With the increasing use of cardiac CT and its precise delineation of the anatomy, it is important for the cardiac imager to become familiar with the normal anatomic structures that compose the interatrial septum and their variants. Furthermore, it is important to recognize pathologic processes occurring in this region other than atrial septal defects and potential imaging pitfalls. This pictorial essay provides a detailed review of these topics with emphasis in CT appearance and related technical aspects.

Large aortic aneurysm mimicking a cardiac tumor

INTRODUCTION

Extrinsic left atrial compression caused by a displaced, crooked descending thoracic aorta is rare. This anomaly may mimic primary cardiac tumors or metastatic neoplasms from the first look.

CASE PRESENTATION

We reported a 78-year-old woman presented to our emergency room with back pain, increased exercise intolerance and intermittent angina. She also had one syncopal event 1 month ago and gastric cancer post gastrectomy history. Subsequent chest plain film showed no mediastinum widening.Two-dimensional echocardiography was performed and revealed a heterogeneous mass as large as 2.3 x 2.4 cm occupying the left atrium (LA). Three-dimensional echocardiography vividly demonstrated that LA was constrained between the aortic valve (AV) and a luminal structure with pulsatile character suggestive of the aorta.

CONCLUSIONS

We successfully demonstrated the detailed structure and location of an anomalous descending aorta on the oblique imaging plane of RT-3DE, which may not be readily available by traditional 2D method.

Fatal cardiac arrest due to an unusual fibroma of the pulmonary valve

Fibroma, the second most common tumor in childhood, usually is a large solitary mass involving the ventricular septum or the left and rarely the right free ventricular wall. An unusual case of a 5.2-year-old boy with a large mass originating from the pulmonary valve is reported. The patient presented for evaluation of a murmur. Echocardiography and cardiac magnetic resonance imaging showed a large tumor extending from the distal right ventricular outflow tract through the pulmonary valve and into the main pulmonary artery causing moderate obstruction. The patient had a fatal cardiac arrest while awaiting surgery. The postmortem examination proved the tumor to be a fibroma.

Lipomatous hypertrophy of the interatrial septum: a pathological and clinical approach

Lipomatous hypertrophy of the interatrial septum (LHIS) is a rare benign disorder that is characterized by accumulation and deposition of fat in the interatrial septum. Its etiology is still unknown, despite the theories that have been suggested. It usually occurs in older, obese people with a higher incidence in women. In most cases, it remains asymptomatic, thus its diagnosis is rarely made during a person's lifetime and it is made incidentally or during autopsy. LHIS can cause atrial arrhythmias, obstructive flow symptoms and sometimes death. The diagnosis of LHIS can be made by the use of imaging techniques, with the best results given by multislice-CT (MSCT) scanning. Surgical intervention is usually avoided and the best management is early diagnosis, reassurance and inactivity. However, in cases of severe superior vena cava obstruction or intractable rhythm disturbance, surgical excision is performed together with reconstruction of the interatrial septum.

Lipomatous Hypertrophy of the Interatrial Septum

OBJECTIVE

To determine the prevalence of lipomatous hypertrophy of the interatrial septum (LHIS) on CT and its metabolic pattern on 18F fluorodeoxyglucose (FDG)-positron emission tomography (PET).

METHOD AND MATERIALS

Eight hundred two CT PET scans were reviewed. Patients were included if the interatrial septum was > or = 1 cm and excluded if there was evidence of malignancy in the adjacent lung, hilum, or mediastinum. CT scans were fused with PET scans, and the mean standardized uptake value (SUV) was calculated over the LHIS, chest wall (CW) fat, and mediastinal blood pool. CT scans were reviewed for presence of excessive fat in the mediastinum, pericardial, peridiaphragmatic, peritoneal, and retroperitoneal regions and for the presence of emphysema. Medical records were reviewed for body mass index (BMI) and history of arrhythmia.

RESULTS

Twenty-three of 802 patients (2.8%) had LHIS on CT (9 women and 14 men); average age was 75.6 years (range, 58 to 95 years). Average BMI of 17 patients (+/- SD) was 31 +/- 4.9 (range, 22.1 to 39.9). Mean CT values were as follows: thickening of LHIS, 1.47 +/- 0.35 cm (range, 1.07 to 2.25 cm); LHIS, - 79.6 + 24.5 Hounsfield unit (HU) [range, - 11 to - 121 HU]. LHIS was dumbbell shaped in 18 patients. Mean SUVs were as follows: LHIS, 1.84 +/- 0.10 (range, 0.48 to 3.48); CW fat, 0.36 + 0.37 (range, 0.04 to 1.98); blood pool, 1.74 + 0.51 (range, 0.25 to 2.71). The SUV of LHIS was greater than the SUV of CW wall fat in all patients (p < 0.0001). There was significant correlation between SUV and thickness of the LHIS on CT (p < 0.0001, r = 0.883). Those with dumbbell-shaped LHIS (p < 0.003) and presence of emphysema (p < 0.0377) had greater LHIS mean SUV.

CONCLUSION

The SUV of LHIS was greater than the SUV of CW fat in all patients. LHIS with greater thickness or dumbbell shape had greater FDG uptake. These findings on CT and PET are important to recognize in order to avoid false-positive FDG-PET interpretations.

Ruptured aneurysm of the left sinus of valsalva discovered 41 years after a decelerational injury

We present an unusual case of ruptured aneurysm of the left sinus of Valsalva discovered 41 years after a car accident. Echocardiography was a key element in establishing the diagnosis of this rare anomaly, which is often congenital but has also been reported as acquired or traumatic in origin.

Lipomatous hypertrophy of the interatrial septum: a prospective study of incidence, imaging findings, and clinical symptoms

BACKGROUND

Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by fat accumulation in the interatrial septum. It typically occurs in elderly, obese patients and may cause arrhythmia.

OBJECTIVES

The purpose of this study was to determine the imaging features of this cardiac pathology using multislice CT (MSCT), and its relationship with clinical findings.

MATERIALS AND METHODS

A total of 1,292 consecutive patients who underwent MSCT of the thorax from September 2001 to August 2002 were prospectively studied. Beside the analysis of patient records, the amount of fat in the interatrial septum, and its size and shape were determined.

RESULTS

Among the 1,292 patients investigated, we found 28 (2.2%) with LHIS. The mean age of affected patients was 72.2 years. MSCT studies revealed a mass of fat attenuation with sharp margins and sparing of the fossa ovalis, resulting in a dumbbell shape in all patients. The median thickness of the interatrial septum was 32 mm (range, 20 to 62 mm), and the median craniocaudal extend was 62 mm (range, 51 to 89 mm). Twenty-one patients (75.0%) showed increased epicardial fat, 18 patients (64.3%) had significant pulmonary emphysema, and 13 of 21 patients (61.9%) showed ECG abnormalities. Three patients underwent functional cardiac MRI studies. In one patient, hemodynamic obstruction by LHIS was shown.

CONCLUSIONS

MSCT scanning is a useful method to diagnose LHIS, a cardiac condition that in our series reached a 2.2% incidence. The lesion shows characteristic features, thus differentiating it from other cardiac tumors. Advanced age, obesity, pulmonary emphysema, and atrial arrhythmias are common additional findings in patients with LHIS.

Role of magnetic resonance imaging for evaluation of tumors in the cardiac region

The aim of this study was to review the role of MRI in the assessment of heart neoplasm, 25 cases with heart neoplasm (10 myxoma, 6 rhabdomyoma, 5 angiosarcoma, 2 mesothelioma, 1 lymphoma, and 1 fibroma) were examined with MRI and echocardiography. Multislice T1- and T2-weighted spin-echo images and static gradient-echo images were taken in appropriate directions with electrocardiogram gating. Gadolinium enhancement was performed in 21 cases. Transthoracic echocardiography was performed in all cases. Except for the 5 patients with rhabdomyoma, the pathological diagnosis was obtained. MRI proved to be useful for tissue characterization of myxoma, angiosarcoma, mesothelioma, and fibroma in cases with tuberous sclerosis. MRI also proved to be useful for detection of the tumor, depiction of contour, relation with other cardiac structures, in cases with myxoma, angiosarcoma, mesothelioma, lymphoma, and fibroma. In the differential diagnosis, MRI provided important information in cases with myxoma, rhabdomyoma, angiosarcoma, and fibroma. In cases with tumors expanding into the mediastinum, such as mesothelioma and fibroma in this report, MRI was useful in determining the location and border. In cases with tumors adjacent to pericardium, MRI was useful in detecting pericardial invasion. Gadolinium enhancement added useful information in cases with myxoma, rhabdomyoma, angiosarcoma, and mesothelioma. The role of MRI with and without Gd enhancement differs somewhat in individual types of heart neoplasm, and adaptation must be considered in each kind of neoplasm. On the other hand, MRI is an essential examination in all cases with a cardiac mass, which has not been diagnosed, since it may provide useful information for the differential diagnosis.