Cardiac valvular disease is a cause of considerable morbidity and mortality. In 2006, the total estimated mortality attributable to valve disease in the United States was 19,989 deaths. Aortic valve disease accounted for 12,471 deaths, and mitral valve disease for 2759 deaths, with the remainder divided evenly between the tricuspid and pulmonary valves.
is a third-year Radiology Resident at Massachusetts General
Hospital (MGH) and Harvard Medical School (HMS), Boston, MA. Dr.
Colen received her medical degree in 2003 from Ponce School of
Medicine in Ponce, Puerto Rico, where she also completed her
internship. In 2003, Dr. Colen became the first medical student
from Puerto Rico to be accepted in the Radiology Residency
program at MGH and the first female medical student from Puerto
Rico to be accepted into a residency at MGH and HMS. When this
article was written,
was a Cardiac Fellow at MGH, Boston, MA.
is a Research Fellow, MGH, Boston, MA.
is a Cardiac Radiologist, MRI and CT, and the Director of
Clinical Cardiac MRI, MGH; and an Instructor of Radiology, HMS,
is the Director of Noninvasive Cardiac and Vascular Imaging, and
the Director of Education, Cardiac MR and CT Program, MGH; and an
Instructor, HMS, Boston, MA.
Multidetector computed tomography (MDCT) is expected to
revolutionize the way the evaluation and work-up of the cardiac
patient is performed. Although invasive coronary and cardiac
angiography maintains a 0.2-mm spatial resolution versus 0.4-mm
in 64-slice MDCT, the emergence of retrospectively
electrocardiographic-gated 64-slice MDCT has resulted in high
spatial resolutions that are not achievable with other
noninvasive cardiac imaging modalities. The purpose of this
article is to describe the MDCT qualitative techniques used to
evaluate valvular lesions and to describe and illustrate a
spectrum of congenital and acquired valvular disease with
Cardiac valvular disease is a cause of considerable morbidity
and mortality. In 2006, the total estimated mortality attributable
to valve disease in the United States was 19,989 deaths. Aortic
valve disease accounted for 12,471 deaths, and mitral valve disease
for 2759 deaths, with the remainder divided evenly between the
tricuspid and pulmonary valves.
Transthoracic and transesophageal echocardiography are the
primary imaging modalities used to evaluate valve disease, although
in some patients it may be difficult to obtain accurate
visualization and evaluation of valvular lesions.
User-operator dependency is an inherent disadvantage, and some
patients have an inadequate acoustic window for scanning.
Transesophageal echocardiography is an invasive procedure and is
contraindicated in patients with recent esophageal surgery, recent
oral ingestion, unstable cervical spine injuries, and unevaluated
gastrointestinal bleeding. Although cardiac magnetic resonance
imaging (MRI) is currently regarded as the noninvasive reference
standard for valve evaluation, it is costly, time-consuming, and
has limited availability. Contraindications for MRI include
pacemakers, implantable cardiac defibrillators, intravascular
stents <6 weeks after implantation, aneurysmal clips, heart
valves installed before 1996, and claustrophobia.
Multidetector-row computed tomography (MDCT) is an emerging
modality in noninvasive cardiac imaging. Using data acquired
throughout the cardiac cycle, it is possible to reconstruct
multiple reconstructions at 10% increments of the R-R interval.
These can then be combined sequentially to provide functional
imaging data sets in a cine loop that allows evaluation for
valvular leaflet morphology and function. The purpose of this
article is to describe the cardiac MDCT techniques that allow
optimal depiction of the cardiac valves, describe the
pathophysiology of a spectrum of valvular diseases, and illustrate
their appearances on 64-slice MDCT.
MDCT scan protocol
For this manuscript, images have been acquired using a 64-slice
MDCT scanner (Sensation 64, Siemens Medical Solutions, Erlangen,
Germany). Our protocol involves intravenous beta-blocker
administration (5 to 25 mg of metoprolol) before each scan to
achieve a heart rate of 60 bpm. Nitroglycerin tablets (0.6 mg) are
administered sublingually just before scanning. The scan range,
based on the scout images, is planned from the carina to the base
of the heart. Scans are acquired in full inspiration. A timing
bolus scan is performed to determine peak opac-ification in the
ascending aorta using an injection of 20 mL of iodinated contrast
(iopamidol 300 mgI/mL) at 5 mL/sec is followed by a 20-mL saline
bolus chaser. For the cardiac scan, 60 to 90 mL of iopamidol 370
mgI/mL is injected into the antecubital vein at 5 mL/sec followed
by 40 mL of saline at 5 mL/sec, and the scan is initiated with a
delay according to the timing bolus delay. Cardiac acquisition
parameters include a collimation of 0.6 mm, slice reconstruction
thickness of 0.75 mm, slice overlap of 0.5 mm, gantry rotation time
of 330 msec, table feed of 3.8 mm/rotation, tube voltage of 120
kVp, and tube current of 850 mAs. Axial images are reconstructed
with a slice thickness of 0.75 mm with 0.4-mm slice overlaps using
a half-scan reconstruction algorithm to achieve a temporal
resolution of 165 msec in the center of gantry rotation. In
subjects with a heart rate >65 bpm or insufficient image quality
due to motion artifacts, multisegment reconstruction is performed.
We find the initial reconstruction phase that produces optimum
image quality is 65% of the cardiac cycle, usually representing the
most motion-free phase of the cardiac cycle. Multifunctional data
sets are reconstructed at 10% intervals of the R-R interval for
functional depiction of the valves throughout the cardiac cycle.
Data sets are transferred to a workstation (Leonardo, Siemens
Medical Solutions, Forchheim, Germany) and multiplanar reformatted
images of each valve are rendered. Valve motion is reviewed in
anatomic appropriate planes in both static multi-phase
reconstruction images and in cine-mode images.
Mitral stenosis (MS) is a narrowing of the inlet valve of the
left ventricle. It commonly leads to inadequate diastolic filling
of the left ventricle. The majority of cases are acquired and are
secondary to rheumatic heart disease. Less common causes include
systemic lupus erythematosus, rheumatoid arthritis, and pulmonary
cardiac carcinoid. Less commonly, left atrial myxoma, thrombus, and
malignant tumor may prolapse into the mitral orifice, causing
"hemodynamic MS." Massive mitral annular calcification may cause
Infective endocarditis with large vegetations may cause thickening
and stenosis of the leaflets. Rarely, congenital MS may be caused
by a "parachute mitral valve" (subvalvular MS) or hypoplastic left
Global radiological assessment
Criteria for grading MS using valve area, transvalvular flow
rate, and transvalvular pressure gradient are well established in
The normal mitral valve orifice usually measures between 4 and 6 cm
. Narrowing of the valve area to <2.5 cm
impedes the free flow of blood into the left ventricle. When the
orifice is reduced to <1 cm
, severe MS results. Willmann et al
found that MDCT allows good to excellent morphological detail of
the mitral valve and apparatus (namely, annulus, leaflets, and
papillary muscles), with the exception of the tendinous chords.
Morphologic changes that are seen on cardiac MDCT in patients
with chronic MS result from left atrial outflow obstruction. An
enlarged left atrium (>4 cm in anteroposterior diameter at the
level of the aortic root) and left atrial appendage are commonly
seen, combined with a normal-sized left ventricle. This leads to
chronic venous pulmonary hypertension and, eventually, right heart
Additional cardiac MDCT findings include an enlarged main pulmonary
artery (PA) of >3 cm at the bifurcation, increased lung
parenchymal groundglass opacity, increased septal lines (Kerley B
lines) and pleural and pericardial effusions.
Congenital: Parachute mitral valve
Parachute mitral valve is caused when the chordae converge on a
major papillary muscle instead of diverging to insert into 2
papillary muscles. The usual 2 mitral valvular leaflets and
commissures are present. The effect creates a stenotic mitral
valve, since the leaflets are held in close apposition. The only
effective communication between the left atrium and the left
ventricle is through the interchordal spaces. Parachute mitral
valve associated with subaortic stenosis occurs 40% of the time and
On MDCT, the leaflets resemble the canopy of a parachute; the
chordae, its shrouds or strings; and the papillary muscle, the
harness. The chordae are often short and thick. This, coupled with
their convergent papillary insertion, allows little mobility of the
leaflets (Figure 1).
Acquired mitral stenosis: Rheumatic heart disease
Rheumatic heart disease (RHD) is the most serious complication of
rheumatic fever (RF) and occurs following pharyngitis with group A
Although the most common cause of MS is RF, the prevalence of MS
has decreased due to the decline in RF because of antibiotic
treatment of "strep throat." Approximately 40% of patients with RHD
have isolated MS. Conversely, rheumatic involvement is present in
99% of stenotic mitral valves excised at the time of mitral valve
Calcification of the mitral valve leaflets are classically seen in
MS of rheumatic origin. There is a narrowing of the orifice during
diastole. The left atrium can be enlarged, although usually not to
the extent seen in mitral regurgitation (Figure 2).
Acquired mitral stenosis: Cardiac myxoma prolapse into
Cardiac myxoma is a benign neoplasm and the most common primary
tumor of the heart. Clinical presentation depends on the location
and morphology of the tumor and its tendency to embolize. It
classically arises as an endocardial intracavitary mass in the left
atrium attached to the fossa ovalis of the interatrial septum.
Fibrous lesions are more likely to produce valvular obstruction
(mitral stenosis), while polypoid, predominantly myxoid, lesions
are more likely to embolize.
For large lesions causing significant hemodynamic compromise, a
pattern mimicking that of MS and pulmonary venous hypertension may
be seen on radiographs. On MDCT, cardiac myxomas appear with a
well-defined spherical or ovoid intracavitary shape, with smooth
contours (Figure 3A). Tumor enhancement is usually homogenous,
although heterogeneous attenuation of myxomas may reflect
hemorrhage, necrosis, cyst formation, fibrosis, or calcification.
Multifunctional data reconstruction provides a cine loop that is
useful for demonstrating tumor motion and possible prolapse of the
mass into the mitral orifice (Figures 3B through 3D).
Mitral regurgitation occurs because of incomplete coaptation of
the mitral valve leaflets, thereby allowing backward blood flow
into the left atrium. Causes include: 1) leaflet abnormalities,
such as leaflet thickening in rheumatic heart disease, perforation
in infective endocarditis, or floppy redundant leaflets; 2) chordae
tendinae abnormalities seen in mitral valve prolapse; 3) chordae
tendinae rupture from trauma, infection, congenital malformation,
or cystic medial necrosis; 4) papillary muscle rupture from
infarct; and 5) mitral annular dilation from left ventricular
dilation of any cause.
Global radiological assessment
In the acute setting, such as acute myocardial infarction, rapid
left atrial and ventricular volume overload result in acute severe
left heart failure and acute pulmonary edema. In individuals with
chronic mitral regurgitation, adaptation of the left atrium and the
left ventricle to the volume load results in left atrial and left
ventricular dilation, with less severe pulmonary vascular
congestion, and, rarely, if ever, pulmonary hypertension. The left
ventricular mass increases with increased chamber volume, resulting
in thickening of the left ventricular myocardium. Pulmonary
arterial dilation and right heart dysfunction are, therefore, less
commonly seen in compensated patients.
If left atrial enlargement is severe, chest radiography may show a
double density sign over the right heart border, which represents
the edge of the left atrium, and there may be splaying of the
carina. Some complications that are seen in MR include left
ventricular failure, atrial fibrillation, and left atrial
Recent studies show a strong correlation between the regurgitant
orifice area at MDCT and the degree of regurgitation.
Moreover, MDCT accurately depicted the underlying morphological
cause of mitral regurgitation, with the exception of rupture of the
Difficulty in the visualization of the tendinae should be overcome
by increased spatial and temporal resolution of more recently
developed scanners. The prognosis of patients with mitral
regurgitation depends on the underlying etiologies and the state of
the left ventricular function with an 80% 5-year survival rate.
Secondary mitral regurgitation: Mitral annular dilatation
secondary to cardiomyopathy
The most common cause of secondary mitral regurgitation is
ventricular dilatation causing stretching of the mitral valve
annulus and displacement of the papillary muscles.
Cardiac MDCT has recently been shown to illustrate noncoaptation of
the mitral leaflets and to estimate the severity of MR accurately
Ancillary findings as to the mechanism of mitral regurgitation,
such as left ventricular enlargement and the resultant atrial
dilatation, are depicted well on CT.
Primary mitral regurgitation: Myxomatous degeneration with
mitral valve prolapse
Mitral valve prolapse (MVP) is the overall most common cause of MR
and occurs when the valve leaflets "billow" backward into the
atrium during systole. The concept that there is an underlying
defect of the connective tissue, which is possibly systemic, is
favored currently. This is further suggested by the finding that
MVP is a prevalent feature in connective tissue disease, such as
Marfan syndrome and Ehlers-Danlos syndrome. Deposition of mucoid
material causes myxomatous degeneration of the mitral valve
leaflets, and associated structures and the collagenous structures
within tendinae are decreased.
Lengthening of the chordae tendineae is a cardinal feature of the
MVP syndrome. The chordae may be congenitally abnormally long or
may become abnormal secondary to trauma, infection, or cystic
medial necrosis. The posterior leaflet is most commonly affected.
Annular dilatation is characteristic, a finding that is rare in
other causes of primary mitral insufficiency. Cardiac MDCT may show
doming and hooding of the leaflets, which may be thickened. Lack of
complete coaptation of the valve leaflets in systole results in MR.
The entity may be complicated by acute rupture of the chordae
tendinae (Figure 5), which is usually a cata- strophic event that
leads to profound cardiogenic and respiratory shock.
Aortic stenosis is a narrowing of the aortic valve orifice which
causes resistance to blood flow across the aortic valve. In young
patients, the major causes are congenital malformation of the cusps
and rheumatic fever.
In older individuals ( >60 years of age), the major causes are
calcification of a bicuspid aortic valve or "degenerative" senile
calcification of a morphologically normal valve.
Average survival depends on the clinical symptoms as follows:
congestive heart failure, 1.5 to 2 years; dyspnea, 2 years; and
an-gina, 3 years.
Global radiological assessment
Cardiac multiplanar reformats allow imaging in any plane. We
usually image the valves in a true-2-chamber view, 4-chamber view,
and short axis view. We also evaluate the aortic valve in a true
cross-sectional plane, similar to echocardiography. This has 2
advantages: 1) they are usually the optimum imaging planes with
which to view the valves; and 2) they are the views cardiologists
are most familiar with. On cardiac MDCT, the 3 cusps of the normal
aortic valve form a "Y," the sinuses forming a clover-leaf
appearance. The normal aortic valve area measures 3 to 4 cm
. Planimetric measurement of an aortic valve area <2 cm
is clinically significant, and <0.8 cm
defines critical aortic stenosis. Studies have shown a strong
correlation between the degree of aortic valve calcification
assessed on MDCT and transvalvular gradients and aortic valve area
measured on Doppler echocardiography.
One group of researchers has suggested that patients with severe
aortic stenosis and marked calcification on MDCT belong to a
high-risk subgroup that may benefit from early aortic valve
replacement, even in the absence of symptoms.
Concentric left ventricular muscle hypertrophy is seen in all
cases, regardless of the pathogenesis.
Congenital aortic stenosis: Bicuspid aortic valve
Bicuspid aortic valve (BAV) is the most common congenital cardiac
malformation. It results from complex abnormal cusp formation
during valvulogenesis, not just the fusion of 2 cusps. Since BAV
causes premature fibrosis and calcification of the aortic valves,
aortic stenosis is the most common complication of BAV. In contrast
to the degenerative form of AS, AS from bicuspid valve presents
earlier, at an age range of 30 to 50 years.
In the absence of the normal 3 cusp clover-leaf appearance, a
bicuspid valve can be easily diagnosed. The classical bicuspid
valve shows 2 symmetric aortic cusps. During diastole, the open
bicuspid aortic valve assumes an ellipsoid shape (Figure 6).
Secondary aortic stenosis: Degenerative aortic valve
Degenerative (se-nile) calcific stenosis is thought to develop
secondary to normal "wear and tear" from hemodynamic injury and
manifests itself usually in the eighth decade. In de-generative
aortic stenosis, the degree of calcification is the strongest
independent risk factor for disease progression and an adverse
MDCT shows 3 distinct separate cusps, thickened by calcifying
fibrosis and distorted by calcified nodular excrescence. The
"updoming" of valve leaflets and the stenosis of the aortic valve
orifice is also seen (Figure 7).
Aortic regurgitation is the diastolic flow of blood from the
aorta into the left ventricle. Incompetence of the aortic valve or
any disturbance of the valvular apparatus (eg, leaflets, annulus of
the aorta) results in aortic regurgitation and may be caused by
abnormalities of the valve leaflets (commonly due to rheumatic
heart disease, bacterial endocarditis) or by dilatation of the
aortic root (commonly due to Marfan syndrome, syphilitic aortitis).
Global radiological assessment
On cardiac MDCT, the severity of valvular dysfunction may be
reflected by the size of the aortic caliber, as well as how far
toward the aortic arch the aortic dilatation extends. The impact of
aortic regurgitation on cardiac hemodynamics is dependent on the
speed of onset of regurgitation. In acute regurgitation, such as in
infective endocarditis (IE) or aortic dissection, the left
ventricle has no time for adaptation, whereas in chronic
regurgitation hypertrophy of the left ventricle allows some
adaptation and clinical presentations may be less severe.
Acute aortic regurgitation: Infective endocarditis
Infective endocarditis (IE) is an infection of the endocardial
surface of the heart, most com- monly the cardiac valves. Most
people have a pre-existing underlying cardiac valve condition
predisposing them to the development of left-sided IE.
is the most common organism.
In the acute setting, vegetations can be clearly depicted (Figure
8A) and are classically on the ventricular side of the aortic valve
in the direction of intracardiac blood flow. Multifunctional
reconstructions can depict incomplete coaptation of the cusps
(Figures 8B and 8C). Multidetector CT may also show complications,
such as aortic wall erosion by infected vegetations and subsequent
endovascular leak into the epicardial fat (Figure 9).
Tricuspid regurgitation occurs because of incomplete coaptation
of the tricuspid valve leaflets, allowing blood to flow backward
into the right atrium. Similar to mitral regurgitation, tricuspid
regurgitation occurs when there is an abnormality of any of the 5
components of the atrio-ventricular valve apparatus, which includes
the leaflets, chordae, annulus, papillary muscles and adjacent
right ventricular (RV) muscle abnormalities. Ebstein's anomaly
accounts for the most common congenital form of this abnormality.
Other causes include endocarditis, carcinoid, floppy valve
syndrome, and connective tissue disorders, such as Marfan
Global radiographic assessment
The normal tricuspid valve area measures 3 to 9 cm
. On MDCT, tricuspid regurgitation is seen by incomplete leaflet
coaptation and the presence of reflux of contrast into the inferior
vena cava and hepatic veins during the first pass of a
contrast-enhanced CT. The presence of reflux can be associated with
tricuspid regurgitation and has a very high specificity and
sensitivity. Tricuspid regurgitation results in right atrial and
ventricular dilation (Figure 10) and clockwise cardiac rotation, in
severe cases. Furthermore, the etiology of tricuspid regurgitation
can usually be inferred from associated morphologic abnormalities
depicted with cardiac MDCT. For example, enlargement of the
pulmonary arteries indicates that pulmonary hypertension may have
mediated the tricuspid regurgitation.
Left heart dilation with left ventricular dysfunction indicates
left heart disease as the likely etiology of the right heart
dysfunction. Rheumatic heart disease may cause calcification of the
tricuspid as well as the mitral valve leaflets.
Congenital tricuspid regurgitation: Ebstein's anomaly
The pathophysiology and morphology of Ebstein's anomaly reflect the
embryological develop- ment of the tricuspid valve. The anterior
leaflet develops first, arising from the mesenchyme. The posterior
and septal leaflets arise through the creation of a diverticulum
and the undermining of the right ventricular myocardium. Failure or
partially occurring undermining of the myocardium causes Ebstein's
anomaly. This explains why the proximal portion of the anterior
valve leaflet is not usually displaced and the anterior leaflet is
the most dysplastic leaflet.
Ebstein's anomaly is defined by apical displacement of the septal
and posterior tricuspid valve leaflets, leading to atrialization of
the inlet of the right ventricle with a variable degree of
dysplasia of an enlarged anterior leaflet. The posterior and septal
tricuspid valves may be deficient or absent (Figure 11).
Most patients exhibit septal bowing due to the increased volume of
the right side of the heart. Roughly 90% of patients have a
concomitant patent foramen ovale or secundum atrial septal
Since the surgical method is tailored for each patient, accurate
assessment of morphologic features and type of Ebstein's anomaly is
important and cardiac MDCT is ideal for such evaluation.
Acquired tricuspid regurgitation: Carcinoid heart
Cardiac involvement has been recognized in more than half of the
patients with carcinoid syndrome and heralds a worse prognosis.
Carcinoid tumors are rare neuroendocrine malignancies that arise
from neural crest amine precursor uptake decarboxylation cells.
Approximately 90% of all carcinoid tumors are located in the
gastrointestinal system. Carcinoid syndrome is characterized by
facial flushing, intractable secretory diarrhea, and
bronchoconstriction. Carcinoid valve lesions characteristically
manifest as fibrous white plaques located on the valvular and mural
endocardium. The valve leaflets are thickened, rigid, and reduced
in area with fibrous tissue proliferation that is present on both
the atrial and ventricular surfaces of the valve.
Carcinoid heart disease is characterized by pathognomonic
plaquelike deposits, resulting in fibrous endocardial thickening,
retraction, and fixation of valvular cusps of the tricuspid valve
and, less frequently, the pulmonary valve. Tricuspid regurgitation
is found in nearly all patients with carcinoid heart disease and
leads to right-heart enlargement.
Cardiac MDCT in cardiac carcinoid depicts thickened tricuspid
valves, which show restricted movement. There may also be thickened
chordinae tendinae (Figure 12). There is almost always concomitant
right atrial enlargement, and, in severe cases, an enlarged
superior vena cava and inferior vena cava. The liver also contains
hypervascular carcinoid metastases.
Pulmonic stenosis is most commonly congenital and can be
valvular (90%), subvalvular, or peripheral (supravalvular).
Valvular pulmonic stenosis is typically an isolated anomaly and
comprises 10% of all congenital heart disease. Acquired causes of
pulmonic stenosis are rare and include carcinoid, rheumatic fever,
and infective endocarditis. Although uncommon in isolated valvular
pulmonic stenosis, a bicuspid valve is found in as many as 90% of
patients with tetralogy of Fallot.
Global radiographic assessment
The normal trileaflet pulmonic valve area measures 2 cm
of body surace area (2.5 to 4.0 cm
). Mild pulmonic stenosis is defined as <1 cm
and severe as <0.5 cm
. Classically, the 3 leaflets are thin and pliant, with partially
fused commissures, resulting in a conical or dome-shaped structure
with a narrowed central orifice. Poststenotic pulmonary artery
dilatation may occur owing to "jet-effect" hemodynamics.
Valvular pulmonary stenosis: Dysplastic pulmonic
Approximately 10% to 15% of patients with valvular pulmonic
stenosis have dysplastic pulmonic valves, which are composed of
myxomatous tissue. Failure of normal development of the pulmonic
valves at 6 to 9 weeks gestation can result in the following
malformations: fusion of 2 cusps, 3 leaflets that are thickened and
partially fused at the commisures, or a single cone-shaped
MDCT depicts a valvular annulus that is small, and the
supravalvular area of the pulmonary trunk is usually hypoplastic.
Poststenotic dilatation is less common with dysplastic valve
stenosis than it is with classic pulmonic stenosis (Figure 13).
Approximately two thirds of patients with Noonan syndrome have
pulmonic stenosis due to dysplastic valves.
Cardiac MDCT continues to broaden its role in the evaluation of
cardiac valve diseases. It may provide an alternative imaging
method for valve evaluation in patients in whom alternative imaging
modalities are unable to provide optimal valve depiction.