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Case 2 - Cardiac pseudotumor due to lipomatous hypertrophy of the interatrial septum
- from Section 1 - Cardiac pseudotumors and other challenging diagnoses
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- By Pejman Motarjem, Desert Radiologists, Stefan L. Zimmerman, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
- Print publication:
- 21 May 2015, pp 4-7
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- Chapter
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Summary
Imaging description
Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign process of the heart characterized by fatty infiltration of the interatrial septum. The diagnosis is made when fat in the interatrial septum measures greater than 20 mm in thickness and it is usually an incidental finding at cardiac imaging.
At echocardiography, LHIS is recognized by echogenic thickening of the interatrial septum. On multiple detector computed tomography (MDCT) (with or without contrast) LHIS is a low-attenuation, < 0 Hounsfield units, bilobed mass with smooth margins that spares the fossa ovalis. It is this sparing of the fossa ovalis which gives this entity its characteristic bilobed or dumbbell-shaped morphology (Figure 2.1). Often, there is cranial extension to the level of the cavoatrial junction and fat may surround the distal superior vena cava (Figure 2.2).
On MRI the morphology of LHIS is similar to MDCT. The LHIS demonstrates hyperintensity on T1-weighted imaging with homogenous signal drop out on a fat-suppressed T1 sequence characteristic of macroscopic fat (Figure 2.2). On post-gadolinium sequences no enhancement is seen.
FDG uptake within the atrial septum at positron emission tomography (PET) examinations may be seen, and is attributed to the variable presence of brown fat within LHIS (Figure 2.3). It is important to note that the benign FDG uptake in LHIS must not be mistaken for a malignant process such adenopathy or metastatic tumor. Fusion PET-CT will help localize radiotracer uptake to the atrial septum and differentiate it from surrounding structures such as the right hilum, pleura or mediastinum. In difficult cases, it may be necessary to correlate PET-CT findings with either MRI or MDCT in order to prevent inappropriate staging of the patient.
Importance
The condition of LHIS is a benign incidental finding and typically does not cause any symptoms. Since it may demonstrate increased FDG uptake on PET/CT, it must not be confused with a malignant process, leading to misdiagnosis, inappropriate follow-up imaging or inappropriate biopsy.
Case 57 - Ductus diverticulum mimicking ductus arteriosus aneurysm
- from Section 7 - Acute aorta and aortic aneurysms
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- By Pejman Motarjem, Diagnostic Radiologist, Stefan L. Zimmerman, Johns Hopkins University
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
-
- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
- Print publication:
- 21 May 2015, pp 181-185
-
- Chapter
- Export citation
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Summary
Imaging description
Ductus diverticulum (DD) is an anatomic variant incidentally found at cardiovascular imaging characterized by a smooth bulge of the anterior wall of the aorta at the aortic isthmus, just distal to the origin of the left subclavian artery.
DD is best visualized on sagittal oblique reconstructions on CT, MRI, or digital subtraction angiography (DSA) (Figures 57.1 and 57.2). DD may be difficult to appreciate on standard axial images. On reconstructions, it is recognized as an anteriorly directed bulge of the undersurface of the aortic arch that extends to the proximal descending thoracic aorta. DD has smooth, gentle margins, and obtuse shoulders.
Importance
DD must not be confused with traumatic aortic transection or ductus arteriosus aneurysm, both of which can occur at the same location and have a greater risk of morbidity and mortality.
Typical clinical case scenario
DD is typically encountered as an incidental finding on CT, MR or DSA and is of no clinical significance. It occurs in approximately 26% of adults and requires no follow-up or treatment.
Differential diagnosis
Traumatic aortic transection, also known as post-traumatic pseudoaneurysm, is found in patients with a history of highvelocity trauma. At cross-sectional imaging, aortic transections arise from the anterior wall of the aorta at the isthmus, similar to DD. However, aortic transections have acute angles with the aortic wall, are irregular in shape and size, and often have a visible intimal flap (Figure 57.3). There may be a narrow neck that communicates with the aorta. Associated periaortic and mediastinal hematoma are typically present with traumatic aortic transection.
Aneurysm of the ductus arteriosus is a rare entity characterized by a saccular aneurysm of the undersurface of the aortic arch in the region of the ductus arteriosus (Figure 57.4). Wall calcifications and partial thrombosis are frequently present. Some believe this entity is due to incomplete obliteration of the patent ductus arteriosus during early development that results in a blind-ending stump communicating with the aortic lumen. Progressive enlargement occurs over years.