ultidetector row computed tomographyMDCT) is an emerging technique for nonin-asive coronary angiography (1). In direct com-arison to invasive angiography, a high level ofiagnostic accuracy for the detection of signif-
cant coronary artery stenoses has been shown2). Accordingly, MDCT is finding increasingse as an alternative imaging modality in theiagnostic testing of patients with suspectedoronary artery disease (CAD) (3). Because
DCT not only acquires a 3-dimensional3D) volumetric dataset of the entire heart butdditionally can be reconstructed at any desiredime instant during the cardiac cycle, it can alsorovide functional information. Consequently,ardiac MDCT allows for a comprehensive
rom the *Department of Cardiology, Leiden University Medical Cardiology, University of California, Irvine, California. Dr. Bristol-Myers Squibb Medical Imaging, Boston Scientific, Medtro
anuscript received October 5, 2007; revised manuscript received Oct
valuation of cardiac structure and function anday be used for a broad range of applications
1). In this article, the role of MDCT in theoninvasive evaluation of cardiac morphologynd function is discussed. An overview of theide range of noncoronary applications of car-iac MDCT is provided, focusing on the as-essment of left ventricular (LV) function,alvular heart disease, and cardiac venousnatomy.
ardiac Function Assessment With MDCT
V volumes and ejection fraction. For globalunction analysis with MDCT, thick slices (2m) are typically reconstructed in the short-
er, Leiden, the Netherlands; and the †Division ofreceives research grants from GE Healthcare,and St. Jude Medical.
ober 14, 2007, accepted October 17, 2007.
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xis orientation throughout the cardiac cycle (every% or 10% of the RR interval) to identify end-iastolic and -systolic phases. Subsequently, LVnd-diastolic and -systolic volumes are derived toalculate left ventricular ejection fraction (LVEF),ither using the Simpson method or volume thresh-ld method. For the Simpson method, endocardialorders are traced manually or with automatedoftware to obtain LV volumes. The thresholdolume, on the other hand, uses the high contrastetween the LV cavity and myocardium to deriveV volumes automatically after manual definitionf the mitral valve plane and LV axis. Examples ofoth methods are provided in Figure 1. The accu-acy of LV volume and ejection fraction measure-ents with MDCT has been investigated exten-
ively. Comparisons with various other imagingodalities, including 2-dimensional (2D) echocar-
iography (4), gated single-photon emission com-uted tomography (SPECT) (5), and magneticesonance imaging (MRI) (6) have consistentlyemonstrated high accuracy of MDCT for thessessment of LV volumes and LVEF.
With the introduction of newer MDCT technol-gy, such as dual-source computed tomographyCT), additional improvements in accuracy for thessessment of LV function can be expected becausef enhanced temporal resolution (7). It is notewor-hy that “ECG pulsing,” the reduction of radiationxposure in systole that is often applied to reduceadiation doses in cardiac CT, does not preventccurate assessment of LV function. Although sys-olic images may have slightly reduced image qual-ty and higher noise, the endocardial borders aretill visualized with sufficient accuracy.egional wall motion. By displaying images in cine-
oop format, regional wall motion can be evaluated inddition to LVEF. In general, the 17-segment models proposed by Cerqueira et al. (8) is applied for thisurpose and segments are scored as normokinetic,ypokinetic, akinetic, or dyskinetic (the latter 2 ofteneing combined for practical purposes). In a recenttudy, excellent agreement of 64-slice MDCT and 2Dchocardiography was shown, with 96% of segmentscored identically on both techniques, resulting in aappa value of 0.82 (9). However, it is important toealize that the agreement was particularly high foregments displaying normal wall motion (99%),hereas slightly lower agreement was observed for
atient with regional contractile dysfunction is pro-ided in Figure 2.yocardial infarction and perfusion. An emerging ap-lication of MDCT is the evaluation of myocardialerfusion. This concept, dating back to animal studiesn the late 1970s (10), is based on the kinetics of theodinated contrast agent used for noninvasive coronaryngiography. Similar to MRI, MDCT datare acquired during administration of a bolusf contrast agent. As a result, hypoperfusedyocardial regions are identified as areas
isplaying hypoattenuation (Fig. 2). Subse-uent measurements of attenuation inounsfield units allow differentiation be-
ween areas of infarction and remote myo-ardium (11). In comparison to the tech-iques traditionally used to visualizeyocardial infarction (gated SPECT andRI), a good accuracy to detect myocardial
nfarction has been observed for MDCT12–14). However, in general, the area ofnfarction seems to be slightly overestimatedy MDCT (11,14).
Importantly, MDCT allows assess-ent of both chronic and acute myocar-
ial infarcts (15). In an animal model ofhronic myocardial infarction, Lardo etl. (16) showed that delayed enhance-ent MDCT imaging could accurately identify
he morphological characteristics of the infarct,ncluding infarct size and transmurality. Further-
ore, the accuracy of MDCT for the assessmentf acute myocardial infarction has been shown inumans (17,18). A close relationship betweennhancement patterns (both early hypoenhance-ent and late hyperenhancement) on MDCT
nd recovery of myocardial function at 3-monthollow-up has been shown, suggesting that
DCT may indeed provide valuable informationor further management after myocardial infarc-ion (18).
Ideally, not only evaluation of scar tissue but alsossessment of myocardial ischemia would be possible.ndeed, one of the major limitations of MDCToronary angiography is the inability to evaluate theunctional significance of detected coronary arteryesions (19). Diagnosis and management, however,ould be substantially improved if this information
ould be obtained in addition to the anatomical data.ecently, the feasibility of adenosine stress myocardialerfusion imaging with MDCT has been shown in aanine model (20). Accordingly, MDCT may have
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erfusion defects in addition to coronary anatomy.owever, it is important to realize that adenosine-
nduced tachycardia may hamper simultaneous inter-retation of the coronary arteries.
ssessment of Valvular Anatomy With MDCT
ecause of the excellent spatial and temporal resolu-ion and the ability to reconstruct the dataset at any
Figure 1. Analysis of LVEF With MDCT
(A) Analysis based on the volumetric threshold method is illustrated4-chamber, and 2-chamber views. The left ventricular end-diastoliclar ejection fraction (LVEF) assessment based on the Simpson methshort-axis slices to calculate volumes and subsequently LVEF. MDCT
Regional Wall Motion With 64-Slice MDCT
ction in end diastole. (B) Short-axis reconstruction in end systole. Aki-e myocardium is observed in the lateral wall (black arrows). In addi-ark endocardial rim) corresponding to previous myocardial infarction. Quantification of left ventricular volumes reveals severely reduced
Cunction (LVEF 28%). Abbreviations as in Figure 1.
ime point during the cardiac cycle, MDCT is aaluable technique for the assessment of valvularisease. However, the recent Appropriateness Criteriaor Cardiac Computed Tomography and Cardiac
agnetic Resonance Imaging (1), from the Americanollege of Cardiology, graded the characterization ofative (and prosthetic) cardiac valves and assessmentf valvular function as an uncertain indication forardiac MDCT. Nonetheless, MDCT permits assess-ent of different aspects of heart valves, including
alvular and annular calcifications, the number ofeaflets, valvular anatomy and geometry, and valve area21–32). Aortic and mitral valves can usually be wellisualized with MDCT, whereas visualization of tri-uspid and pulmonary valves is not reliable. This isikely because the left-sided heart valves are thicker,nd because contrast enhancement in the right atriumnd ventricle is not as homogeneous as in the left-ided chambers. If right-sided heart valves are to beisualized, the contrast injection protocol must bedjusted to ensure enhancement in the right cardiachambers during image acquisition. This usually re-uires a longer injection of contrast as compared with
om left to right, end-diastolic images are displayed in short-axis,me is semi-automatically derived. (B) An example of left ventricu-s provided. Endocardial contours are drawn on reconstructedmultidetector row computed tomography.
. Frvoluod i
Figure 2. Analysis of
(A) Short-axis reconstrunesia and thinning of thtion, hypoattenuation (dis present in this region
T coronary angiography studies.
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The assessment of valve areas in MDCT is basedn direct planimetry because the quantification ofressure gradients and transvalvular flow is notossible with MDCT (33). Correlative studies onDCT and echocardiography for the assessment
f aortic and mitral valve stenosis and regurgitationre summarized in Table 1.ortic valve. Various aspects of the aortic valve cane assessed with MDCT (34). Calcification can beuantified in nonenhanced datasets (35). However,or the accurate assessment of valve morphologynd quantification of the orifice area, contrast-nhanced scans are necessary (33,36,37). In 57atients referred for MDCT coronary angiography,bbara et al. (33) performed planimetry of the
ortic valve at 5 different time points during theardiac cycle (0 to 200 ms after the R-wave). It wasoted that image quality for analysis of the aorticalve area was optimal at 50 ms after the R-wavemidsystole). Finally, MDCT may be of value forhe assessment of aortic stenosis or aortic regurgi-
Table 1. Assessment of Aortic and Mitral Valve Stenosis and Re
Authors (Ref. #)Patients
(n) Referral Reason
Aortic valve stenosis(correlation: AVA)
Feuchtner et al. (21) 46(30 AS)
Pre-operative (CABG)
Alkadhi et al. (22) 40(20 AS)
Coronary angiography
Bouvier et al. (23) 103(30 AS)
Coronary angiography
Piers et al. (24) 30 AS N/A
Laissy et al. (25) 40 AS Pre-operative (AVR)
Habis et al. (26) 52 AS Pre-operative (AVR)
Feuchtner et al. (27) 36 AS Coronary angiography
Aortic valve regurgitation(correlation: ROA)
Feuchtner et al. (28) 71(48 AR)
Several‡
Jassal et al. (29) 64(30 AR)
Coronary angiography
Alkadhi et al. (30) 30 AR Several§
Mitral valve stenosis(correlation: MVA)
Messika-Zeitoun et al. (31) 29 MS N/A
Mitral valve regurgitation(correlation: ROA)
Alkadhi et al. (32) 44(19 MR)
Coronary angiography
*TTE in 27 patients, TEE in 3 patients. †TTE in 32 patients, TEE in 10 patients. ‡Adisese (n � 8), aortic dissection (n � 1), atypical chest pain after cardiac surgeryangioplasty (n � 8).AR � aortic regurgitation; AS � aortic stenosis; AVA � aortic valve area; AVR �
regurgitant orifice area; TEE � transesophageal echocardiography; TTE � transthor
ation. Numerous studies have shown close corre-ation between MDCT and echocardiography forhe assessment of aortic valve opening area andegurgitant orifice area (Table 1).itral valve. It has been shown that contrast-
nhanced MDCT allows visualization of mitralalve annulus, leaflets, papillary muscles, and evenendinous cords (Fig. 3). Typically, a long-axislane reconstructed perpendicular to the mitralalve yields optimal image quality for assessment ofitral valve morphology. Furthermore, the optimal
ystolic and diastolic reconstructions for functionalssessment are at 5% and 65% of the RR interval,espectively (38). Importantly, it has been shownhat there is an excellent agreement between
DCT, echocardiography, and surgery (by meansf direct visualization) for the assessment of thick-ning of the mitral valve leaflets and the assessmentf mitral valve and annular calcifications (39). Sev-ral studies have investigated mitral valve stenosisnd regurgitation with MDCT (Table 1).
gitation With MDCT
CTnique
Collimation(mm)
ComparisonTechnique Correlation (L
-slice 16 � 0.75 TTE r � 0.89, p � 0.001
-slice 16 � 0.75 TTE/TEE TTE: r � 0.95, p � 0.001TEE: r � 0.99, p � 0.001
TTTE
-slice 16 � 0.625 TTE/TEE* N/A
CT N/A TTE r � 0.60, p � 0.01
-slice 16 � 0.4 TTE r � 0.77, p � 0.001
-slice 64 � 0.6 TTE r � 0.76, p � 0.001
-slice 64 � 0.6 TTE/TEE† TTE: r � 0.88, p � 0.001TEE: r � 0.99, p � 0.001
ssess suspected coronary artery(n � ms after previous balloon
aor ography; EBCT � electronphy; � not applicable; ROA �
acic echocardiography.
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anagement of valvular heart disease. An MDCTcan may be of clinical value in the surgical andercutaneous treatment of valvular heart disease. Itas been shown that MDCT has a high diagnosticccuracy to rule out CAD in patients with aortictenosis before surgical aortic valve replacement40). In addition, LV function and valvular anat-
Figure 3. Assessment of Mitral Valve Anatomy With MDCT
This reconstructed long-axis view clearly shows how the anat-omy of the mitral valve and the subvalvular apparatus can beassessed. In the diastolic phase, the mitral valve leaflet (openarrow), the tendinous cords (solid arrow), and the papillarymuscles (PM) are well visualized. Ao � aorta; LV � left ventricle;MDCT � multidetector row computed tomography.
Figure 4. Assessment of the Aortic Valve With MDCT
In this patient, a bicuspid aortic valve is demonstrated with contraspanel). The extent and location of calcifications (white arrows) can
during cardiac surgery (right panel).
my (including the aspect of the mitral and aorticalve [bicuspid/tricuspid], the diameter of the valve,nd the extent of calcifications of the valve andnnulus) can be accurately assessed with MDCT.n example of a bicuspid aortic valve assessed withDCT is shown in Figure 4. Preoperative knowl-
dge of these aspects may influence the surgicaltrategy or type of valvular prosthesis.
Recently, the feasibility of percutaneous mitralnnuloplasty in patients with severe mitral regurgi-ation has been reported (41). The rationale of thisechnique is to remodel the mitral annulus bylacing a device in the coronary sinus, adjacent tohe mitral annulus. In this context, MDCT canrovide useful information by depicting the rela-ionship between the coronary sinus, mitral annu-us, and coronary arteries (42). An example of a 3Dolume-rendered reconstruction depicting this rela-ion is shown in Figure 5. Importantly, it has beenoted that in the majority of the patients, theoronary sinus is located cranial to the mitral valvennulus (43). Furthermore, in 68% of the patients,he circumflex artery coursed between the coronaryinus and the mitral annulus, with an increased riskf occlusion of the circumflex artery when perform-ng percutaneous mitral annuloplasty (43).
ssessment of Left Atrium andulmonary Vein Anatomy
he role of MDCT in catheter ablation proceduresor atrial fibrillation has rapidly expanded in theast few years. Radiofrequency catheter ablation hasecome an important and increasingly used therapyor patients with drug-refractory atrial fibrillation
hanced multidetector row computed tomography (MDCT) (leftwell visualized with MDCT and correlate well with the findings
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44). The aim of these procedures is to electricallysolate the pulmonary veins because these are theominant foci initiating atrial fibrillation (45). Theenoatrial junctions, the antrum, anatomical varia-ions, and other left atrial landmarks, such as theidge between the left superior pulmonary vein andhe left atrial appendage, are critical structures todentify during catheter ablation procedures.
With the use of standard orthogonal planes and 3Dolume-rendered reconstructions, MDCT can depicthe number, location, and size of the pulmonary veins46). Thereby, MDCT can accurately visualize varia-ions in pulmonary vein anatomy. Anatomical varia-ions include single insertions (common ostium) ofhe pulmonary veins and additional pulmonary veinsFig. 6). In a large cohort of 201 patients undergoing
DCT scanning, Marom et al. (47) noted a left-ided common ostium in 14% of patients, and andditional right-sided pulmonary vein in 28% ofatients. In addition, wide variation in left atrialnatomy in patients with atrial fibrillation may exist. Itas been shown that the anatomy and size of the lefttrial appendage, roof, and septum varies considerablyn patients with atrial fibrillation (48). All of theseariations in left atrial and pulmonary vein anatomyave important implications for catheter ablation pro-edures. Therefore, a detailed “road map” of the lefttrium and pulmonary veins is needed, both beforend during the actual ablation procedure. In addition,etailed knowledge on surrounding structures such ashe esophagus and the coronary arteries is of criticalmportance for avoiding complications such as atrioe-ophageal fistula (49) and coronary artery injury (50).ecause MDCT can provide highly detailed informa-
ion on left atrial and pulmonary vein anatomy and theurrounding structures, it can provide the necessarynatomical reference for ablation procedures.mage integration. Ideally, the anatomical informa-ion derived from the MDCT scan is available on-lineuring the catheter ablation procedure. Recently, im-ge integration systems have been introduced thatllow the fusion of MDCT images and conventionallectroanatomical maps (51). With dedicated algo-ithms, the left atrial cavity and pulmonary veins arextracted from the raw MDCT data (Fig. 7). The 3Dolume-rendered reconstruction of the left atrium andulmonary veins can then be aligned with the recon-tructed electroanatomical map during the actual ab-ation procedure. This registration process is based on
inimizing the distance between the MDCT imagend the electroanatomical map (Fig. 7). Eventually,
he catheter ablation can then be performed with the e
se of the real anatomy of the left atrium and pulmo-ary veins.Both pre-clinical (52) and clinical (53) validation
tudies have shown the feasibility of importing theDCT scan into the electroanatomical mapping
ystem, and the subsequent use of the MDCT scanuring the actual catheter ablation procedure. Theeported accuracy (or registration error) ranges be-ween 1.9 � 0.6 mm and 2.4 � 0.4 mm (52–55).he accuracy of the image integration process maye limited by motion caused by respiration, changesn heart rhythm and heart rate, and different fluidtatus during scanning and during the ablationrocedure. Furthermore, variation of pulmonaryein location throughout the cardiac cycle mayecrease the accuracy (56). However, potential ad-antages of the integration of MDCT and thelectroanatomical map include the possibility toonitor the exact catheter position in relation to
he endocardial border, the pulmonary veins, andhe surrounding structures. This may facilitate cath-
Figure 5. Coronary Venous Anatomy and Relation BetweenCoronary Sinus and Mitral Annulus
With the use of 3D volume rendered reconstructions, the anat-omy of the coronary venous system and the relation betweenthe coronary sinus (CS) and the mitral valve annulus can beassessed. In this patient, the CS courses along the posterior wallof the left atrium (LA), rather than along the mitral valve annu-lus. In patients with a large distance between the CS and themitral annulus (indicated by the white arrow), a percutaneousmitral annuloplasty may not be feasible. GCV � great cardiacvein; LMV � left marginal vein; PIV � posterior interventricularvein; PVLV � posterior vein of the left ventricle.
ter ablation procedures and may help in avoiding
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otential complications such as pulmonary veintenosis, radiation skin burns, and the like.
Importantly, it has been shown that the use ofDCT during the catheter ablation procedure may
educe procedure and fluoroscopy times, and even
Figure 6. Pulmonary Vein Anatomy Assessment With MDCT
Three-dimensional volume-rendered reconstructions of 64-slice MDCTanatomy is shown. Four pulmonary veins with separate insertions in thanatomy. (B) A common ostium of the left-sided pulmonary veins is sh(D) An aberrant insertion of the additional pulmonary vein is present (may likely impact catheter ablation procedures. LIPV � left inferior pultor row computed tomography; RIPV � right inferior pulmonary vein;
Figure 7. Image Integration: Fusion of MDCT and Electroanatom
The process of image integration consists of several steps. First, mu(left panel). With the use of dedicated algorithms based on settinginto different structures (middle panel). During the catheter ablatiostructed electroanatomical map (registration). Finally, the actual ablpulmonary veins (right panel). Based on the real anatomy derived
red dots, right panel) can be targeted around the pulmonary veins.
ay improve the outcome of the ablation proce-ure. Kistler et al. (55) treated a total of 94 patients,sing conventional mapping alone (n � 47) andith MDCT image integration (n � 47). It wasoted that in the image integration group, fluoros-
s to illustrate pulmonary vein anatomy. (A) Normal pulmonary veinft atrium (LA) are present. (B to D) Variations in pulmonary vein(arrows). (C) An additional right-sided pulmonary vein (arrow).
w). All of these anatomical variations in pulmonary vein anatomyary vein; LSPV � left superior pulmonary vein; MDCT � multidetec-� right superior pulmonary vein.
l Mapping
tector row computed tomography (MDCT) scanning is performednsity levels for Hounsfield units, the MDCT scan is segmentedocedure, the segmented left atrium is aligned with the recon-n can be performed guided by the anatomy of the left atrium andthe MDCT scan, the radiofrequency lesions (represented by the
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opy times were significantly shorter (49 � 27 mins. 62 � 26 min, p � 0.05) and the number ofatients with maintenance of sinus rhythm withoutntiarrhythmic medication was significantly higher83% vs. 60%, p � 0.05). However, these data needo be confirmed in larger, randomized trials.
ssessment of Coronary Venous Anatomyith MDCT
umerous clinical trials have shown that in appropri-te patients, cardiac resynchronization therapy (CRT)rovides substantial symptomatic benefit and reducesortality (57–59). The implantation of a CRT device
equires the insertion of an LV pacing lead, generallyt the posterolateral wall of the LV. In more than 90%f patients, this can be accomplished via a transvenouspproach. The main factor determining the success oftransvenous LV lead implantation is cardiac anat-
my, particularly of the coronary venous system.owever, there is large interindividual variation in the
Figure 8. Congenital Anomaly of the Coronary Venous System i
This patient has a persistent left superior vena cava (LSVC) and a mupper panel shows a 3-dimensional volume-rendered reconstructioels show multiplanar reformatted images, where the target vein (po(arrows). Left ventricular lead implantation for cardiac resynchronizthese. A noninvasive pre-procedure evaluation with multidetector r
very helpful.
natomy of the cardiac veins (60). Ideally, the anatomyf the cardiac venous system should therefore bessessed noninvasively before the implantation proce-ure. Several studies (43,61,62) have shown the fea-ibility of MDCT for the noninvasive assessment ofardiac venous anatomy (Fig. 5). In particular, inatients with abnormal venous anatomy, MDCT canrovide valuable information on the course of theoronary sinus and its tributaries. Abnormal venousnatomy assessed with MDCT is shown in Figure 8.n addition to the anatomical data, MDCT can alsorovide quantitative data of the coronary venous struc-ures, including dimensions of the ostium of theoronary sinus and the diameter of the target veins61).
Importantly, with the use of MDCT, an associ-tion between anatomical variations and the historyf a previous myocardial infarction has been shown62). In patients with a history of infarction, a leftarginal vein was significantly less often observed
s compared with control patients and CAD pa-
Patient Referred for CRT
dly enlarged coronary sinus and great cardiac vein (GCV). Thelustrating the LSVC and coronary venous system. The lower pan-olateral branch) for left ventricular lead implantation is identifiedtherapy (CRT) is significantly more complicated in patients likeomputed tomography for elucidation of the “road map” can be
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ients (Fig. 9). None of the patients with a lateralnfarction and only 22% of patients with anteriornfarction had a left marginal vein (62). Thisre-procedural identification of patients who lackhe presence of posterolateral branches with a suf-cient diameter to allow passage of a pacemaker
ead has important implications for clinical practice.ccordingly, MDCT may be used to identify pa-
ients who do not have suitable target branches, andherefore could be referred directly for a minimallynvasive surgery for epicardial LV lead placement.
ssessment of Cardiac Morphology:pecific Conditions
ongenital heart disease. The role of cardiacDCT in the diagnosis and follow-up of congen-
tal heart disease has increased over the past fewears. Detailed anatomical information, even inomplex situations, including congenital coronaryrtery anomalies, atrial and/or ventricular septalefects, aortic coarctation, and pulmonary anoma-
ies, can be obtained by MDCT (63). An examplef an anomalous pulmonary venous connectionssessed with MDCT is shown in Figure 8. In
Normals CAD Myocardial Infarction
PIV PVLV LMV
Variations in Coronary Venous Anatomy
se of 64-slice multidetector row computed tomography, the preva-e PIV, PVLV, and LMV was assessed in 28 normal control patients, 38th coronary artery disease (CAD), and 34 patients with a history ofinfarction. The LMV was less frequently identified in patients with ayocardial infarction as compared with CAD patients and control% vs. 61% and 71%, respectively). This may hamper left ventricularning in case of CRT. *p � 0.01. **p � 0.0001. Abbreviations as indapted from Van de Veire et al. (62).
ddition, accurate visualization of cardiac anatomy d
y MDCT may facilitate interventional procedures,uch as catheter ablation procedures for atrial ar-hythmias after surgical correction of congenitaleart disease (64). Although the use of radiation
imits repeated MDCT scanning in the follow-upf congenital heart disease patients, MDCT is lessampered by metal artifacts compared with MRI,nd MDCT may be particularly valuable for pa-ients with implanted pacemakers or defibrillators.ardiac masses. An MDCT scan may be of value inhe evaluation of patients with suspected cardiacasses (tumor or thrombus), in particular in pa-
ients with technically limited images from echo-ardiography or MRI (1). Intracardiac thrombi,ost frequently located in the left atrial appendage,ay be depicted as contrast-filling defects, and can
e detected with a high sensitivity (but rather lowpecificity) using MDCT (65).ericardial abnormalities. Abnormal pericardial con-itions, such as pericardial thickening and calcifi-ation, can be evaluated with MDCT. In particular,fter cardiac surgery or when echocardiography isnconclusive, MDCT can provide detailed informa-ion on the presence or absence of pericardialffusion (66).
ssessment of Surrounding Structures
hrenic nerves. Phrenic nerve injury after catheterblation for atrial fibrillation is a rare but seriousomplication (67). In addition, phrenic nerve stim-lation and subsequent diaphragmatic stimulationas been commonly associated with LV lead place-ent for CRT (68). Both injury and stimulation of
he phrenic nerves can be explained by the proxim-ty of the phrenic nerves to the pulmonary andoronary veins (69). Most commonly, the phrenicerves are identified with the use of high-outputacing maneuvers. However, noninvasive evalua-ion of phrenic nerve anatomy and the relationshipith the pulmonary and coronary veins may help
he cardiologist in planning ablation and LV leadmplantation procedures.
Unfortunately, it is difficult to image thin, iso-ated nerve fibers with MDCT. Matsumoto et al.70) visualized the blood vessels that accompany thehrenic nerve and used the course of these vessels asmarker of the phrenic nerve. Along with the
ericardiophrenic artery and vein, the phrenicerves form a neurovascular bundle (right pericar-iophrenic bundle and left pericardiophrenic bun-
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le). Using 3D volume-rendered reconstructions of
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Figure 10. Assessment of the Pericardiophrenic Bundles With MDCT
Examples of the left (left panel) and right (right panel) pericardiophrenic bundles as shown with 64-slice multidetector row computed
tomography (MDCT). The yellow arrows indicate the course of the neurovascular bundles.
Figure 11. Use of MDCT in LV Lead Implantation
(A) A 3-dimensional volume-rendered reconstruction demonstrates the left pericardiophrenic bundle (LPCB), representing the left phrenicnerve. The course of the LPCB is indicated by white and yellow arrows. (B) The same view as in (A), after adjustment of the windowlevel. The course of the LPCB is again represented by yellow arrows. In this reconstruction, the GCV and the lateral marginal branch(white arrow) are well visualized. Consequently, the relationship between the phrenic nerve and the cardiac veins can be well appreci-ated. (C) An occlusive venogram of the coronary sinus. The tortuous lateral marginal branch (white arrow) is clearly visualized. A goodcorrelation with the noninvasive evaluation by MDCT (B) is seen. This vein was chosen as the target branch because it was not seen tointersect the course of the LPCB. (D) A unipolar lead placed in the target vein (white arrows). High-output pacing from the lead during
the procedure did not reveal any diaphragmatic capture. Abbreviations as in Figures 3 and 5.
ccptvirwianfehnpErbaaaitvbmuoeev
Hdilaisapt
C
TuactittotcM
ATV
RTM
R
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ontrast-enhanced MDCT scans, the anatomicalourse of the right pericardiophrenic bundle and leftericardiophrenic bundle can be assessed and rela-ions between the left phrenic nerve and cardiac andascular structures may be analyzed (Fig. 10). Non-nvasive visualization of the phrenic nerves and theirelation with the pulmonary and coronary veinsith the use of MDCT may be of value in planning
nterventional procedures. An example of the visu-lization of the coronary veins and the phrenicerves with the use of MDCT in a patient referredor CRT is shown in Figure 11. By depicting thexact course of the phrenic nerves, MDCT mayelp avoid injury or stimulation of the phrenicerves during catheter ablation and LV lead im-lantation procedures.sophagus. Visualization of the esophagus and itselation to the posterior wall of the left atrium maye of interest in patients referred for catheterblation of atrial fibrillation. The development oftrioesophageal fistulas is a lethal complication ofblation procedures, likely caused by direct thermalnjury of the esophagus (44,49). The relation be-ween the esophagus and the left atrium is highlyariable (71), and visualization of the esophagusefore and during the catheter ablation proceduresay be important. It has been shown that with the
se of MDCT, the relationship, size, and thicknessf the tissue layers between the left atrium and thesophagus can be determined (72). Importantly, thesophagus lies close to the ostia of the pulmonaryeins in more than 90% of the patients, and the left
agutti P, et al. Diagnostic performance with echocardiogra
owever, the early enthusiasm has considerablyied down, and it is increasingly realized that staticmages of the esophagus and the left atrium are ofimited to no value in patients undergoing left atrialblation. This is in large part because the esophaguss a mobile structure. It has been frequently ob-erved to move during the course of a singleblation procedure (73). Therefore, if imaging iserformed to determine the atrioesophageal rela-ionship, it has to be done in real time.
onclusions
he imaging modality of MDCT has potential forse in diagnosis of a wide variety of cardiac diseasesnd in guiding a variety of invasive and surgicalardiac procedures. The main attraction of thisechnology is the ability to provide comprehensivenformation and likely decrease the need for addi-ional testing. The 4-dimensional character of theechnique allows an evaluation of cardiac morphol-gy and function. Whereas assessment of LV sys-olic function is well validated, evaluation of myo-ardial infarction and myocardial perfusion with
DCT warrants further study.
cknowledgmenthe authors acknowledge the assistance of J. M.an Werkhoven in preparing the figures.
eprint requests and correspondence: Dr. Laurens F.ops, Department of Cardiology, Leiden Universityedical Center, Albinusdreef 2, 2333 ZA Leiden, the
atrial and esophageal walls are very thin (72). Netherlands. E-mail: [email protected].
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