Mitral valve insufficiency –
Pre-operative dynamic CT assessment

Yingying Zhuang, MD1; Lili Guo, MD1; Jiandong Zhang, MD1; Xi Zhao, MD2
1 Department of Radiology, Huai’an No.1 People’s Hospital Affiliated to Nanjing Medical University
2 Siemens Healthineers, China

A 52-year-old female patient, with a 10-year history of uncontrolled hypertension and chronic bronchitis, was hospitalized due to a severe pneumonia complicated by acute heart and respiratory failure. She was intubated and placed on a ventilator due to a severe dyspnea. An echocardiography revealed an enlarged left ventricle (LV), as well as a mitral insufficiency (MI) caused by a prolapse of the anterior mitral leaflet. However, it was inconclusive about a mitral valve (MV) vegetation. Despite various anti-infection efforts, the patient developed septicemia. An infective endocarditis was suspected. A surgical MV replacement was planned and a cardiac CT examination was requested to evaluate the coronaries and to rule out a MV vegetation prior to surgery.

CT images showed normal coronary arteries, apart from a mild stenosis (about 30%) in the distal left anterior descending artery (LAD) and the right coronary artery (RCA) (Fig. 1). The anterior leaflet of the MV was thickened and prolapsed (Fig. 2) showing a "whip-like" motion. LV function analysis (Fig. 3) revealed an increased volume at both end-systole (ES) and end-diastole (ED) suggesting a LV enlargement. The myocardial mass was increased, indicating LV hypertrophy. Stroke volume and cardiac output were significantly increased with a normal ejection fraction (EF). No MV vegetation or calcification were observed. Subsequently, a mechanical valve replacement was performed, confirming a moderate to severe MI caused by multiple chordae tendineae ruptures in the A2 and A3 areas. The patient recovered and was discharged.

Curved MPR images show normal coronary arteries, except for a mild stenosis (about 30%) in the distal LAD and the RCA.

Fig. 1: Curved MPR images show normal coronary arteries, except for a mild stenosis (about 30%) in the distal LAD (Fig. 1b) and the RCA (Fig. 1a).

VRT images of the LV long axis show the prolapse of the thickened anterior leaflet of the MV at the ES and the ED.

Courtesy of Department of Radiology, Huai’an No.1 People’s Hospital Affiliated to Nanjing Medical University

Fig. 2: VRT images of the LV long axis show the prolapse of the thickened anterior leaflet of the MV at the ES (Fig. 2a) and the ED (Fig. 2b).

LV function analysis reveals an increased volume at both ES and ED suggesting LV enlargement. An increased myocardial mass indicates LV hypertrophy. Stroke volume and cardiac output are significantly increased with a normal EF.

Courtesy of Department of Radiology, Huai’an No.1 People’s Hospital Affiliated to Nanjing Medical University

Fig. 3: LV function analysis reveals an increased volume at both ES and ED suggesting LV enlargement. An increased myocardial mass indicates LV hypertrophy. Stroke volume and cardiac output are significantly increased with a normal EF.

This movie shows the dynamic movement of the MV. The anterior leaflet of the MV is prolapsed showing a "whip-like" motion.

Courtesy of Department of Radiology, Huai’an No.1 People’s Hospital Affiliated to Nanjing Medical University

Fig. 4: This movie shows the dynamic movement of the MV. The anterior leaflet of the MV is prolapsed showing a "whip-like" motion.

MI is a heart valve disorder that requires surgical repair or replacement of the MV. Transthoracic echocardiography is the main evaluation method; however, it has a few limitations that depend on the operators experience, patients, and instruments. Although a cardiac CT is primarily performed to evaluate coronary artery disease, it shows high diagnostic performance in helping the physicians to detect a MV prolapse and to predict a MV replacement before surgery.

Among the CT findings, bi-leaflet prolapse and valve morphology features, such as leaflet thickening, calcification or mitral annular calcification (MAC), are the most important predictors of an unrepairable MV.[1] Recent advances in 3D and 4D imaging techniques for cardiac CT enable detailed visualizations of the MV anatomy, complexity and dynamics.[2] In this case, a retrospective ECG gated spiral scanning is performed acquiring data throughout the complete cardiac cycle. Multiple series are then reconstructed at every 5% of the cardiac cycle, allowing for visualization of the MV morphology and dynamic movement. The same data is also used for LV function analysis, which reveals LV enlargement and hypertrophy with normal output.

A tube voltage of 90 kV is selected for better contrast and lower radiation dose. Other advanced techniques, such as CARE Dose4D™ (real-time anatomic exposure control) and ADMIRE (advanced modeled iterative reconstruction), are also applied to further reduce the radiation exposure to the patient. Due to the inherent high temporal resolution of 66 ms of the dual source scanner SOMATOM Force, optimal image quality is achieved for evaluation of both coronaries and MV, with only one bolus of 40 mL contrast agent. This case shows that cardiac CT can be used as an alternative or complimentary imaging modality to echocardiography for pre-operative MV evaluation.

Scanner

Scan area

Heart

Scan mode

Retrospective ECG-gated spiral scan

Scan length

141 mm

Scan direction

Cranio-caudal

Scan time

2.1 s

Tube voltage

90 kV

Effective mAs

570 mAs

Dose modulation

CARE Dose4DTM

CTDIvol

43.23 mGy

DLP

750.3 mGy cm

Rotation time

0.25 s

Pitch

0.3

Slice collimation

192  x 0.6 mm

Slice width

0.75 mm

Reconstruction increment

0.5 mm

Reconstruction kernel

BV40, ADMIRE 3

Heart rate

85-86 bpm

Contrast

350 mgL/mL

Volume

40 mL + 40 mL saline

Flow rate

5 mL/s

Start delay

4 s