Echocardiography remains the primary imaging modality for diagnosing infective endocarditis (IE). However, in cases of poor TTE quality or high clinical suspicion, TEE is recommended. Despite its utility, TEE has limitations due to artifacts from prosthetic valves and difficulty in assessing extracardiac complications.

Cardiac CT overcomes these challenges, demonstrating high sensitivity (96%) and specificity (97%) for detecting valvular and perivalvular lesions, particularly in the aortic position [1,2,3]. It is especially valuable in prosthetic valve endocarditis (PVE), where artifacts limit TEE accuracy. CT excels in detecting abscesses, pseudoaneurysms, intracardiac fistulas, and valve dehiscence, making it indispensable when TEE is inconclusive or when paravalvular complications are suspected.

• Valvular Vegetations: These appear as low- to moderate-attenuation lesions or focal valve leaflet thickening. Larger, mobile vegetations (>10 mm) pose a higher embolization risk and often necessitate surgical intervention. Prosthetic valve vegetations present unique diagnostic challenges due to artifacts, mitigated by advanced techniques like dual-energy CT.

  

  Fig 3: A 22-year-old male patient with a history of surgically corrected D-TGA. Axial (A) and sagittal (B) cardiac CT images showed vegetations (arrows) on the biological pulmonary valve, with associated perivalvular inflammation. The diagnosis of infective endocarditis (IE) on the biological prosthetic valve was confirmed, with Exophiala dermatidis as the causative fungal pathogen. Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 4: Orthogonal aortic valve- (A) and left ventricular outflow tract- (B,C) oriented contrast-enhanced chest CT images showed vegetations on the prosthetic aortic valve in a 73-year-old male patient. Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 5: Orthogonal aortic valve- (A) and left ventricular outflow tract- (B,C) oriented contrast-enhanced chest CT images showed a prosthetic aortic valve with an abundant amount of irregular soft-tissue density material on the valve. This material predominantly involved the free edge of the valve, extending to the aortic root and causing irregular involvement of the cusps, primarily the non-coronary cusp. Additionally, soft-tissue density material was observed in the periaortic region (50 HU on non-contrast and approximately 100 HU post-contrast administration), without evidence of hypodense collections to suggest abscess formation. Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.

• Perivalvular Pseudoaneurysm: An abnormal cavity adjacent to heart valves that communicates with surrounding structures, typically resulting from the drainage of a perivalvular abscess into vessels such as the aorta.

  

  Fig 6: Orthogonal aortic valve-oriented contrast-enhanced chest CT images revealed (A) a low-attenuation soft-tissue valvular lesion with irregular borders, located on the low-pressure ventricular side of the aortic valve (arrow), and (B) a cavity (*) in contact with the aortic root, showing contrast enhancement (200-400 HU) with a sacular morphology and a narrow neck. Notably, there was loss of the periaortic fat plane, suggestive of phlegmonous changes or early abscess formation (O). Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  In prosthetic valves, pseudoaneurysms are frequently associated with valve dehiscence. High-resolution cardiac CT visualizes pseudoaneurysms as contrast-filled outpouchings (200–400 HU), distinguishing them from abscesses, which exhibit peripheral enhancement. Dynamic systolic expansion and diastolic compression are observed. Additional findings, such as an internal thrombus, adjacent inflammatory changes, and pericardial effusion, may aid diagnosis. Due to the risk of rupture, surgical intervention is generally required.
  

  Fig 7: A 36-year-old male with a history of congenital heart disease presented to the emergency department with a one-week history of progressive dyspnea, which worsened with minimal exertion, and fever. Non-invasive coronary artery CT angiography images (ECG gating): (A) Axial, (B) Coronal, and (C) Sagittal views showed a large periprosthetic pseudoaneurysm (yellow arrow) located at the medial contour of the aortic valve. A smaller pseudoaneurysm was also observed at the lateral contour of the aortic valve (blue arrow). Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 9: Axial images from non-invasive coronary artery CT angiography showing a large periprosthetic pseudoaneurysm (*) with a wide communication (arrow), located at the medial contour of the aortic valve. The lesion is positioned below the left coronary trunk, exerting a moderate mass effect (yellow). Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 11: Coronal volume-rendered CT images (A,B) show a large periprosthetic pseudoaneurysm located at the medial contour of the aortic valve from the same patient as in figure 7.

• Perivalvular Abscess and Fistula: A perivalvular abscess is a necrotic collection adjacent to the valve, which can evolve into a pseudoaneurysm if it communicates with the cardiovascular lumen. Echocardiography shows irregular hypoechoic fluid collections or non-homogeneous thickening[4]. Cardiac CT reveals low-attenuation collections with peripheral enhancement, best seen in the delayed contrast phase. Signs of early infection include fat stranding and extension into the myocardium or pericardium.

• Perivalvular Fistula: Abnormal communications between adjacent chambers or major vessels, often due to infective endocarditis. These are common in PVE and may lead to severe hemodynamic consequences, including heart failure. The most frequent type, an aortocavitary fistula, may connect the sinus of Valsalva to the right ventricle or left atrium[5]. Gerbode defects (left ventricle to right atrium) are another serious complication. Multimodal imaging (TEE, cardiac CT angiography, and color Doppler ultrasound) is required for accurate diagnosis. Aortocavitary fistulas are associated with poor prognosis due to complications such as ventricular septal defects and atrioventricular block.

  

  Fig 10: A 62-year-old male with a history of endocarditis on a native aortic valve, with a known pseudoaneurysm, presented with dyspnea. Cardiac CT images in axial (A) and sagittal (B) slices, and cardiac MRI SSFP in the aortic valve plane (C) showed a known paravalvular aortic pseudoaneurysm (*), extending circumferentially around the entire left sinus. In its portion closest to the valve, a fistula with a 5mm orifice and high velocity was present, extending toward the right ventricular outflow tract (yellow arrow).

• Prosthetic Valve Dehiscence: Occurs when infection at the valve annulus leads to prosthetic valve separation, causing paravalvular leaks. More common with mechanical valves, this condition can be identified on echocardiography by detecting regurgitant flow and prosthetic rocking motion. Cardiac CT reveals malalignment of the prosthesis and tissue defects between the annulus and prosthesis. Dynamic CT assesses rocking motion (>15°), and phase-contrast MRI quantifies regurgitant flow. Accurate diagnosis requires multimodal imaging to differentiate leaks from artifacts and assess paravalvular channels.

• Systemic Embolization: Despite advances in IE management, embolic events (EEs) remain a major cause of morbidity, affecting 10% to 50% of cases. The central nervous system is most commonly involved, worsening prognosis. The spleen is highly susceptible to embolization, leading to infarcts and abscesses. Even sterile embolization can result in splenic abscesses due to vascular occlusion. Renal involvement includes glomerulonephritis (immune-mediated), renal infarction, and renal abscesses, with infarction being the most frequent. The liver may also be affected through hematogenous seeding, although hepatic abscesses are more often associated with direct spread from biliary disease or gastrointestinal infections. Many embolic events are clinically silent, suggesting they are underdiagnosed.

  

  Fig 12: A 64-year-old patient with fever and blood culture results positive for Staphylococcus aureus. (A) Non-invasive coronary CT angiography showed calcification and thickening of the cardiac valve cusps, compatible with endocarditis. A pseudoaneurysm was seen on the anterior aspect of the annulus, arising from the commissure between the non-coronary and right coronary valve cusps. Another pseudoaneurysm was observed on the posterior aspect of the annulus, arising from the annulus/left ventricular outflow tract (arrows). (B, C) Axial and sagittal contrast-enhanced abdominal CT images showed a lytic lesion on the anterior part of L2, involving the L1-L2 intervertebral disc space, compatible with spondylodiscitis. (D) Axial contrast-enhanced abdominal CT image showed a hypoattenuating wedge-shaped lesion (*) in the posterior aspect of the splenic upper pole, likely related to endocarditis, suggestive of splenic infarction. (E) Axial contrast-enhanced abdominal CT image showed a low-attenuation wedge-shaped lesion in the right kidney, suggestive of embolic infarction. Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 13: A 43-year-old male, ex-IVDU, HCV positive, with acute endocarditis on a native mitral valve and severe mitral insufficiency, presented with neurological focality. An urgent brain non-contrast CT (A) showed hypodensity in the right basal ganglia, consistent with an ischemic lesion in the deep MCA territory (*), and a slight mass effect on the frontal horn of the lateral ventricle (yellow arrow). Two cortical-subcortical hypodensities with hemorrhagic components were noted in the left temporo-occipital (blue arrow) and left parietal regions, along with a small right temporal hemorrhagic focus (red arrow), consistent with septic emboli. A follow-up non-contrast CT (B,C), performed 5 days later, showed persistent hypodensity in the right basal ganglia with hemorrhagic transformation (blue arrow). The previously noted cortical-subcortical hypodensities were evolving (green arrows). Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.
  

  Fig 14: (A) Axial contrast-enhanced chest CT image showed a low-attenuation soft-tissue lesion with irregular borders located on the non-coronary cusp of the prosthetic aortic valve (arrow). (B) Axial contrast-enhanced abdominal CT image showed a hypoattenuating wedge-shaped lesion () in both kidneys, with a cortical ring sign, suggestive of embolic infarction. (C) Coronal contrast-enhanced abdominal CT image showed a hypoattenuating wedge-shaped lesion () in both kidneys, with a cortical ring sign, suggestive of embolic infarction. Department of Radiology, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain.