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[Diagnosis of left atrial masses by computed tomography: with special reference to the differentiation between mural
Insights
Computed tomography (CT) effectively differentiates left atrial thrombi from myxomas by analyzing calcification, CT values, shape, and movement. This imaging approach aids in diagnosing these distinct left atrial masses.
Area of Science:
- Radiology
- Cardiovascular Imaging
- Diagnostic Imaging
Background:
- Left atrial masses, including mural thrombi and myxomas, present diagnostic challenges.
- Accurate differentiation is crucial for appropriate patient management and treatment strategies.
Purpose of the Study:
- To compare the computed tomographic (CT) features of left atrial mural thrombi with those of left atrial myxomas.
- To identify characteristic CT findings that facilitate differentiation between these two conditions.
Main Methods:
- Utilized a third-generation computed tomography (CT) system to evaluate left atrial masses.
- Analyzed imaging characteristics such as calcification, mean CT values (Hounsfield units - HU), shape, and movement.
- Reconstructed coronal and sagittal images were employed for detailed anatomical assessment.
Main Results:
- Left atrial mural thrombi (n=12) often showed calcification (approx. one-third) and marked mitral valve calcification. Mean CT values ranged from +17.5 to +89.8 HU (avg +44.5 HU). Thrombi appeared heterogeneous and irregular.
- Left atrial myxomas (n=2) lacked calcification. Mean CT values averaged +30.2 HU, lower than thrombi. Myxomas were ovoid and homogeneous.
- ECG-gated CT revealed pendular movement of myxomas through the mitral orifice, though attachment sites were difficult to discern.
Conclusions:
- Computed tomography (CT) findings including appearance, mitral valve calcification, mean CT value, shape, and movement are key for diagnosing left atrial masses.
- Characteristic CT features allow for reliable differentiation between left atrial mural thrombi and myxomas.
Abstract:
Computed tomographic features of left atrial mural thrombi were compared with those of left atrial myxomas using a third generation system. In seven of 23 patients with mitral valvular disease, computed tomography (CT) demonstrated a total of 12 left atrial mural thrombi. There was calcification in about one-third of the thrombi and marked calcification of the mitral valve in all the seven cases. Mean CT value of the 12 thrombi ranged from +17.5 to +89.8 Hounsfield units (HU) (average +44.5 HU), and in only one it was below +20 HU. All thrombi appeared to be heterogeneous and irregular in shape such as elliptic, triangular or flat on cross-sectional tomogram. In addition, reconstructed coronal and sagittal imagings from serial CT images were very useful for localizing the calcification in the thrombi and determining the site of the attachment of the thrombi to the atrial wall. On the other hand, calcification of the tumor or mitral valve was not detected in two patients with left atrial myxomas by CT. The mean CT value of myxoma was averaged +30.2 HU, which was lower than that of thrombi. Both myxomas were ovoid in shape and appeared to be homogeneous in CT images. ECG gated CT revealed pendular movement of the tumor which prolapsed through the mitral orifice into the left ventricular inflow tract during diastole and backed into the left atrium during systole, although it was slightly difficult to detect the site of the attachment of the tumor. In conclusion, we should evaluate appearances, calcification of the mitral valve, mean CT value, shape and movement in the computed tomographic diagnosis of left atrial masses. In consideration of these characteristic findings, differentiation between mural thrombi and myxomas could be made.