Aidan Raney

Cardiac magnetic resonance imaging: infarct size is an independent predictor of mortality in patients with coronary artery disease

BACKGROUND Cardiac magnetic resonance imaging (CMR) can accurately determine infarct size. Prior studies using indirect methods to assess infarct size have shown that patients with larger myocardial infarctions have a worse prognosis than those with smaller myocardial infarctions. OBJECTIVES This study assessed the prognostic significance of infarct size determined by CMR. METHODS Cine and contrast CMR were performed in 100 patients with coronary artery disease (CAD) undergoing routine cardiac evaluation. Infarct size was determined by planimetry. We used Cox proportional hazards regression analyses (stepwise forward selection approach) to evaluate the risk of all-cause death associated with traditional cardiovascular risk factors, symptoms of heart failure, medication use, left ventricular ejection fraction, left ventricular mass, angiographic severity of CAD and extent of infarct size determined by CMR. RESULTS Ninety-one patients had evidence of myocardial infarction by CMR. Mean follow-up was 4.8±1.6 years after CMR, during which time 30 patients died. The significant multivariable predictors of all-cause mortality were extent of myocardial infarction by CMR, extent of left ventricular systolic dysfunction, symptoms of heart failure, and diabetes mellitus (P<.05). The presence of infarct greater than or equal to 24% of left ventricular mass and left ventricular ejection fraction less than or equal to 30% were the most optimal cut-off points for the prediction of death with bivariate adjusted hazard ratios of 2.11 (95% confidence interval 1.02-4.38) and 4.06 (95% confidence interval 1.73-9.54), respectively. CONCLUSIONS The extent of myocardial infarction determined by CMR is an independent predictor of death in patients with CAD.

Right Atrial Cavotricuspid Isthmus: Anatomic Characterization with Multi–Detector Row CT

PURPOSE To retrospectively evaluate the anatomic characteristics of the right atrial cavotricuspid isthmus (CTI) by using 64-section multi-detector row computed tomography (CT). MATERIALS AND METHODS Institutional review board approval and waiver of informed consent were obtained for this HIPAA-compliant study. The anatomic region of the CTI was evaluated in 201 patients (116 men and 85 women; mean age, 58 years +/- 11 [standard deviation]) who underwent coronary multi-detector row CT. CTI length was assessed along three parallel isthmic levels (paraseptal, central, and inferolateral). Central isthmus depth was classified as straight (3 mm), concave (>3 to </=5 mm), or pouchlike (>5 mm). Measurements were obtained during three cardiac phases: midsystole, middiastole, and atrial contraction. Subthebesian recess dimensions and eustachian ridge width were measured. Distances from the atrioventricular node artery to the coronary sinus, from the right coronary artery (RCA) to the inferior vena cava, and from the RCA to the tricuspid valve annulus were measured. Software was used for statistical analysis. RESULTS At middiastole, the paraseptal isthmus (mean length, 20 mm +/- 3.5; range, 11-34 mm) was significantly shorter than the central isthmus (24 mm +/- 4.3; range, 12-43 mm) and the central isthmus was shorter than the inferolateral isthmus (27 mm +/- 4.8; range, 13-45 mm) (P < .001). The longest CTI measurements were obtained during midsystole, and the shortest were obtained during atrial contraction (40% variation per cardiac cycle). Isthmus contraction occurred primarily in the posterior segment of the central isthmus (RCA to inferior vena cava distance). At middiastole, the central isthmus was straight in 8% of patients, concave in 47% of patients, and pouchlike (>5 mm) in 45% of patients. The mean depth was greater during atrial contraction (6.3 mm +/- 2.1) than in midsystole (4.3 mm +/- 1.5) and middiastole (5.1 mm +/- 1.8) (32% variation during cardiac cycle). A subthebesian recess greater than 5 mm deep was identified in 45% of patients. In 24% of patients, a thick eustachian ridge greater than 4 mm was seen. The atrioventricular node artery passed close to the coronary sinus wall (mean distance, 2.1 mm +/- 0.7; range, 1-6 mm). CONCLUSION Cardiac multi-detector row CT provides extensive information regarding the size and morphology of the CTI and its related structures.

Imaging of Patent Foramen Ovale with 64-Section Multidetector CT

PURPOSE To investigate the feasibility of 64-section multidetector computed tomography (CT) by using CT angiography (a) to demonstrate anatomic detail of the interatrial septum pertinent to the patent foramen ovale (PFO), and (b) to visually detect left-to-right PFO shunts and compare these findings in patients who also underwent transesophageal echocardiography (TEE). MATERIALS AND METHODS In this institutional review board-approved HIPAA-compliant study, electrocardiographically gated coronary CT angiograms in 264 patients (159 men, 105 women; mean age, 60 years) were reviewed for PFO morphologic features. The length and diameter of the opening of the PFO tunnel, presence of atrial septal aneurysm (ASA), and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet (grade 1, <or=1 cm; grade 2, >1 cm to 2 cm; grade 3, >2 cm). In addition, 23 patients who underwent both modalities were compared (Student t test and linear regression analysis). A difference with P < .05 was significant. RESULTS A flap valve, seen in 101 (38.3%) patients, was patent at the entry into the right atrium (PFO) in 62 patients (61.4% of patients with flap valve, 23.5% of total patients). A left-to-right shunt was detected in 44 (16.7% of total) patients (grade 1, 61.4%; grade 2, 34.1%; grade 3, 4.5%). No shunt was seen in patients without a flap valve. Mean length of PFO tunnel was 7.1 mm in 44 patients with a shunt and 12.1 mm in 57 patients with a flap valve without a shunt (P < .0001). In patients with a tunnel length of 6 mm or shorter, 92.6% of the shunts were seen. ASA was seen in 11 (4.2%) patients; of these patients, a shunt was seen in seven (63.6%). In 23 patients who underwent CT angiography and TEE, both modalities showed a PFO shunt in seven. CONCLUSION Multidetector CT provides detailed anatomic information about size, morphologic features, and shunt grade of the PFO. Shorter tunnel length and septal aneurysms are frequently associated with left-to-right shunts in patients with PFO.

Multidetector computed tomography shows intramyocardial fat deposition

BACKGROUND Intramyocardial fat deposition occurs as an age-related process and in multiple pathologic processes. OBJECTIVE We evaluated the presence of left ventricular (LV) and right ventricular (RV) intramyocardial fat with 64-slice multidetector computed tomography (MDCT). METHODS One hundred persons with no history of coronary artery disease (47 women, 53 men; mean age [+/- SD], 53 +/- 12.2 years) and 25 patients with CT findings of myocardial infarction (17 men, 8 women; mean age, 71.3 +/- 9.6 years) were studied for intramyocardial fat in defined segments of the ventricles (17 LV and 10 RV segments) at 3 levels. Fat deposition was defined as density range of -30 to -190 Hounsfield units on images both before and after contrast. RESULTS In healthy persons, LV intramyocardial fat was primarily located in the basal segments (5% anteroseptal, 5% inferior), and RV intramyocardial fat was primarily located in the anterolateral (24% of base, 23% of mid) and inferolateral (27% base, 27% mid) segments. Older age was associated with an increased odds of RV (sex-adjusted odds ratio [OR] per decade increment, 1.61; 95% confidence interval [CI], 1.11-2.33; P = 0.012) but not LV (OR, 0.97; 95% CI, 0.67-1.40; P = 0.85) intramyocardial fat. Compared with women, men had a lower risk of LV (95% CI, 0.1-0.64; P = 0.004) but not RV (95% CI, 0.35-1.87; P = 0.62) intramyocardial fat. Patients with old myocardial infarction (>3 years) had increased percentage of fat in infarcted left ventricles at all 3 levels (P <or= 0.004). CONCLUSIONS Intramyocardial fat can be detected by MDCT and is common in healthy and infarcted myocardium.

Integrated IVUS-OCT Imaging for Atherosclerotic Plaque Characterization

For the diagnosis of atherosclerosis, biomedical imaging techniques such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed. The combined use of IVUS and OCT is hypothesized to remarkably increase diagnostic accuracy of vulnerable plaques. We have developed an integrated IVUS-OCT imaging apparatus, which includes the integrated catheter, motor drive unit, and imaging system. The dual-function imaging catheter has the same diameter of current clinical standard. The imaging system is capable for simultaneous IVUS and OCT imaging in real time. Ex vivo and in vivo experiments on rabbits with atherosclerosis were conducted to demonstrate the feasibility and superiority of the integrated intravascular imaging modality.

Integrated IVUS-OCT for real-time imaging of coronary atherosclerosis.

Objective Combined use of optical coherence tomography (OCT) and intravascular ultrasound (IVUS) is a potential method for accurate assessment of plaques characteristics and vulnerability. The aim of this study is to develop and evaluate the feasibility of a fully integrated intracoronary OCT-IVUS imaging technique to visualize plaques in living animals.

Integrated intravascular optical coherence tomography (OCT) - ultrasound (US) catheter for characterization of atherosclerotic plaques in vivo

A miniature integrated intravascular optical coherence tomography (OCT) - ultrasound (US) catheter for real-time imaging of atherosclerotic plaques has been developed, providing high resolution and deep tissue penetration at the same time. This catheter, with an outer diameter of 1.18mm, is suitable for imaging in human coronary arteries. The first in vivo 3D imaging of atherosclerotic microstructure in a rabbit abdominal aorta obtained by an integrated OCT-US catheter is presented. In addition, in vitro imaging of cadaver coronary arteries were conducted to demonstrate the imaging capabilities of this integrated catheter to classify different atherosclerotic plaque types.

Integrated IVUS-OCT catheter for in vivo intravascular imaging

For the diagnosis of atherosclerosis, biomedical imaging techniques such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed. The combined use of IVUS and OCT is hypothesized to remarkably increase diagnostic accuracy. We report our progress on the probe design and imaging system for achieving a miniature catheter that is capable for in vivo animal study. The integrated IVUS-OCT catheter is featured by a sequential arrangement of an ultrasound transducer and an OCT probe. The capability of the integrated IVUS-OCT imaging catheter and system is demonstrated by in vitro and in vivo imaging experiments of rabbit abdominal aorta.