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Introduction/Aim. Aortic stiffness is a key determinant of cardiovascular morbidity and mortality. Acute Exacerbations of COPD (AECOPD) are accompanied by a spike in systemic stiffness. We investigated an important constituent of systemic stiffness, aortic strain (AS), in a prospective observational cohort study of patients admitted to our tertiary centre with doctor-diagnosed AECOPD. The primary hypothesis was that AS would be increased at exacerbation in comparison to recovery, and the secondary hypothesis was that AS would be associated with clinical and biochemical parameters. Methods. 67 individuals underwent dynamic ECG-gated 256-multidetector CT both during hospitalisation for AECOPD and following discharge and clinical recovery. Ascending aortic cross-sectional area was measured at 10% ECG R-R intervals at the ascending aorta midpoint (mid-way between aortic valve and brachiocephalic trunk). AS was calculated as (maximum area a- minimum area)/minimum area. Paired ttests and Pearson correlations were used for analysis. Results. AS was lower at recovery compared to AECOPD (10.2 +/- 6.4 vs 8.3 +/- 4.2, mean +/- SD, P = 0.01) and it was negatively correlated with age (r = -0.434, P < 0.001). AI was not associated with FEV1, diffusing capacity, emphysema index, left ventricular ejection fraction, coronary artery calcium score, troponin, b-type natriuretic peptide, length of stay, baseline modified Medical Research Council dyspnoea score, Charlson Comorbidity Index or COPD Assessment Test. Conclusion. AS is higher during AECOPD than at recovery. However, it was not associated with other measures of disease and comorbidities beyond that of older age. Our findings suggest that complex mechanisms govern vascular stiffness in COPD; processes that are amplified during AECOPD.

Introduction/Aim. An increased ratio of pulmonary artery (PA) to aortic diameter (PA:A) on computed tomography (CT) correlates with increased pulmonary artery pressure [1]. PA:A > 1 identifies pulmonary hypertension and in COPD is associated with increased risk of hospitalised exacerbations [2]. Conventional CT has been used in previous studies investigating PA:A, however only samples a single asnapshota at a random point in the cardiac cycle. We hypothesised that ECG-gated, dynamic 256-multidetector CT (256-MDCT) would demonstrate variability in PA:A throughout the cardiac cycle, not identifiable with conventional CT [3]. We further hypothesised that PA:A would be higher at exacerbation versus recovery. Methods. Paired dynamic 256-MDCT were performed both during acute exacerbation and following exacerbation recovery. PA:A was based on the maximal PA and aortic diameter at 10% R-R intervals. The primary outcome was to assess the number of cases where the PA:A ratio crossed 1 at any point in the cardiac cycle. The secondary outcome was the change in PA:A ratio from acute scan to recovery scan. Results. Pairs of CT scans were compared in 63 cases admitted to our hospital with a COPD exacerbation. PA:A was variable throughout the cardiac cycle (highest in systole and lowest in diastole). In 12/63 (19.0%) of acute scans and 14/63 (22.2%) of recovery scans, PA:A crossed the threshold of 1. Figure 1 illustrates the variability in PA:A in the overall population during the cardiac cycle at acute exacerbation and at recovery. There was a reduction in mean PA:A ratio between the acute and recovery scans of 0.0159 (P < 0.0001). Maximal PA diameter was increased in the acute scan cohort by a mean of 0.22 mm in comparison to recovery (P = 0.0031). Conclusion. In patients with COPD, PA:A varies throughout the cardiac cycle and the timing of scan acquisition impacts this measurement. Dynamic CT allows better characterisation of PA:A assessment compared to conventional CT. PA:A inc

Certain pulmonary lesions may be challenging to biopsy with conventional computed tomography percutaneous lung biopsy (CTPLB) under local anaesthesia (LA) which requires consistent patient breath holding to minimise complications. We aim to describe and evaluate the feasibility of CTPLB under general anaesthesia (GA) with apnoea, comparing results to patients undergoing biopsy under LA. This was a retrospective analysis of CTPLB with 18 GA and 137 LA patients. All biopsies were performed using a co-axial needle system in the radiology department on a multi-detector CT scanner with patient positioning determined by assessing shortest distance to target lesion. GA cases were performed under relaxant anaesthesia with intermittent positive pressure ventilation. Lower lobar lesion location and a combination of size and location (including proximity to critical structures) were indications for GA biopsy in >90% of patients. Mean lesion size for GA biopsies was 18 mm and control group 30 mm (P < 0.006) and mean pleura to lesion distance 29 and 11 mm, respectively (P < 0.0009). Pneumothorax rates were lower in our GA biopsy group (11%) compared to control group (42%) (P < 0.05). No anaesthetic complications were encountered. All GA samples were diagnostic. Based on a small number of patients, CTPLB under GA with apnoea seems a safe, feasible alternative to conventional CTPLB under LA for technically challenging lesions. This technique is routinely employed at our centre allowing access to lesions previously deemed unsafe to biopsy.Copyright © 2021 The Royal Australian and New Zealand College of Radiologists

BACKGROUND: Both the direct anterior approach (DAA) and posterior approach (PA) to THA have known advantages and disadvantages. The comparison between DAA and PA THA has been widely explored during the early postoperative period. However, few randomized trials have compared these approaches at a minimum follow-up of 5 years; doing so would be important to establish any differences in mid-term outcomes or complications. QUESTIONS/PURPOSES: We performed a randomized trial comparing DAA and PA in THA in terms of (1) patient-reported outcome scores, (2) quality of life and functional outcomes assessed by the EQ-5D and 10-meter walk test results, (3) radiographic analysis, and (4) survivorship and surgical complications at a minimum of 5 years follow-up. METHOD(S): Two hip specialist surgeons performed both DAA and PA THA using the same THA components at two hospital sites. One hundred twelve patients on the elective THA surgical waitlist were invited to participate in the study. Thirty-four patients did not meet the study's inclusion criteria and were excluded, and three patients declined to participate in the study. The remaining 75 patients who were eligible were randomized into DAA and PA groups. Thirty-seven patients were initially randomized to receive DAA THA, but two did not and were excluded, resulting in 48% (35 of 73) of patients who received DAA THA; 52% (38 of 73) of patients were randomized into and received PA THA. Over a minimum 5 years of follow-up, 3% (1 of 35) of DAA patients were lost to follow-up, and none of the patients undergoing PA THA were lost. A per-protocol analysis was adopted, resulting in further patients being excluded from analysis. Of the 73 study patients, 99% (72; DAA: 35, PA: 37) were analyzed at 1 year, 95% (69; DAA: 34, PA: 35) were analyzed at 2 years, and 72% (52; DAA: 23, PA: 29) were analyzed at 5 years. The primary outcome was the Oxford Hip Score (OHS) and WOMAC score. Secondary outcomes included the EQ-5D and EQ-5D VAS score

Introduction: Pulmonary hypertension is associated with reduced survival in COPD but is difficult to detect. There are major limitations to clinical application of Echocardiography and cardiac MRI in severe COPD. Dynamic CT can overcome these limitations and simultaneously assess lungs, pulmonary vasculature and cardiac function within the same study acquisition. Method(s): 37 COPD patients (mean/SD FEV1 48/24% predicted) underwent retrospective ECG-gated contrast enhanced 256-slice multidetector CT following clinical recovery from a hospitalized exacerbation. Main PA cross-sectional area (CSA) was measured (perpendicular to long axis at midpoint between pulmonary valve and PA bifurcation) at 10% intervals from 0-90% of the RR interval. Pulsatility was calculated from ((maximum CSA-minimum CSA)/minimum CSA x 100)). Cardiac function was determined using images reconstructed at 10% intervals from 0%-90% of the R-R interval. We assessed pulsatility of the main pulmonary artery in severe COPD and its relationship with %LAA (emphysema) and right ventricular function. Result(s): Mean/SD PA pulsatility was reduced in this patient cohort at 16.9/5.9%. PA pulsatility was significantly correlated with emphysema index (r=-0.365, p=0.031) and with reduced RVEF (r=0.483, p=0.0025). Conclusion(s): Reduced PA pulsatility is common in severe COPD and related to both severity of emphysema and impaired right ventricular ejection fraction. Impairment of PA pulsatility occurs early in pulmonary hypertension and MDCT may permit earlier case detection in COPD.

We investigated five mid carpal instability syndrome patients with four dimensional computer tomography. Each patient underwent a wide field of view CT, with 16 cm Z axis with four motions including flexion/ extension, radial/ulnar deviation, dart throwing and supination/pronation. We present our initial observations of the three abnormalities which were identified and we postulate that 4D CTwill become a significant adjunct to routine management of patients who present with mid carpal instability syndrome.

Introduction/Aim: Pulmonary hypertension (PH) in COPD is associated with increased disability and reduced survival. Detection of PH in COPD is challenging due to limitations of echocardiography and potential risks associated with right heart catheterization (RHC). The main pulmonary arteries (PA) become progressively less distensible in PH. Previous studies have shown PA distensibility to correlate well with measured mPAP at RHC. We assessed relationships between PA distensibility, cardiac function and emphysema index measured using dynamic ECGgated MDCT. Method(s): 34 patients with stable COPD (mean[SD] age 65.8[9.7], FEV1% 43.9[22.5], 18 male) underwent dynamic retrospective ECGgated MDCT. Emphysema was quantified by CT densitometry based upon a density threshold of <-950 Hounsfield Units (HU). The main pulmonary artery cross-sectional area (CSA) was measured at 10% intervals from 0-90% of the R-R interval. PA distensibility (%) was calculated as ((maximum CSA-minimum CSA)/minimum CSA) x 100. Cardiac function parameters were assessed using semi-automated software with manual correction if required. The relationship of PA distensibility with both emphysema index and right ventricular ejection fraction (RVEF) was tested via Pearson's r. Result(s): Mean[SD] PA distensibility was low (16.5[5.9]%). PA distensibility was significantly negatively correlated with emphysema index (r=-0.365, p = 0.031) and positively correlated with reduced RVEF (r=0.483, p=0.0025). Conclusion(s): Dynamic MDCT permits simultaneous evaluation of emphysema, PA pressure and right ventricular performance. Increased severity of emphysema appears associated with reduced PA distensibility. Impaired PA distensibility appears associated with decreased RVEF. Dynamic MDCT provides a valuable tool for assessment of heart-lung interaction in COPD.

Objectives This study describes the feasibility and accuracy of a novel computed tomography (CT) fractional flow reserve (FFR) technique based on alternative boundary conditions. Background Techniques used to compute FFR based on images acquired from coronary computed tomography angiography (CTA) are described. Boundary conditions were typically determined by allometric scaling laws and assumptions regarding microvascular resistance. Alternatively, boundary conditions can be derived from the structural deformation of coronary lumen and aorta, although its accuracy remains unknown. Methods Forty-two patients (78 vessels) in a single institution prospectively underwent 320-detector coronary CTA and FFR. Deformation of coronary cross-sectional lumen and aorta, computed from coronary CTA images acquired over diastole, was used to determine the boundary conditions based on hierarchical Bayes modeling. CT-FFR was derived using a reduced order model performed using a standard desktop computer and dedicated software. First, 12 patients (20 vessels) formed the derivation cohort to determine optimal CT-FFR threshold with which to detect functional stenosis, defined as FFR of <=0.8, which was validated in the subsequent 30 patients (58 vessels). Results Derivation cohort results demonstrated optimal threshold for CT-FFR was 0.8 with 67% sensitivity and 91% specificity. In the validation cohort, CT-FFR was successfully computed in 56 of 58 vessels (97%). Compared with coronary CTA, CT-FFR at <=0.8 demonstrated a higher specificity (87% vs. 74%, respectively) and positive predictive value (74% vs. 60%, respectively), with comparable sensitivity (78% vs. 79%, respectively), negative predictive value (89% vs. 88%, respectively), and accuracy (area under the curve: 0.88 vs. 0.77, respectively; p = 0.22). Based on Bland-Altman analysis, mean intraobserver and interobserver variability values for CT-FFR were, respectively, -0.02 +/- 0.05 (95% limits of agreement: -0.12 to 0.08) and 0

Introduction/Aim: Pulmonary hypertension is an important complication of Chronic Obstructive Pulmonary Disease (COPD), however it can be difficult to identify. Reduction in Carbon Monoxide Transfer Factor (TLCO) is a feature of both emphysema and pulmonary hypertension. CT can quantify emphysema via the emphysema index (EI). In addition, pulmonary artery distensibility (PAD) is known to correlate with mean pulmonary artery pressure measured at right heart catheterisation and can be measured simultaneously using ECG-gated CT. The impact of pulmonary artery distensibility on the relationship of FEV1 and Emphysema Index (EI) with TLCO has never been examined. The aim of this study is to determine the effect of PAD, FEV1(%) and EI on TLCO, with the hypothesis that the addition of PAD data would help account for variability in TLCO unexplained by the other two parameters. Method(s): Patients were analysed from the 4C cohort, a prospective group of patients who were recruited over a 1 year period during acute exacerbations of COPD and had subsequent ECG gated CT and pulmonary function tests performed during stable periods. After excluding patients with missing data, significant motion artefact on CT and those unable to perform TLCO, 34 patients were entered into a multiple linear regression model. Result(s): TLCO corrected for haemoglobin was entered as the dependent variable and in order FEV1(%), EI and PAD were entered into the regression model as independent variables. Overall, the model was able to explain 62.5% of the variation in TLCO (Corrected R2 0.625). Both FEV1(%) and EI were significantly correlated with TLCO after controlling for the other variables (FEV1(%) r = 0.512 and P<0.001, EI r =-0.431 and p = 0.003) However, after controlling for FEV1pp and EI, PAD was not significantly correlated with TLCO (r =-0.055, p = 0.637). Conclusion(s): FEV1(%) was significantly positively correlated and Emphysema Index was significantly negatively correlated with TLCO after

Introduction/Aim: Acute cardiac dysfunction during COPD exacerbations is associated with poor prognosis. It is common, yet consistently under-recognized in clinical practice. This partly reflects the specific limitations of echocardiography, chest X-ray (CXR) and ECGin an emphysematous population.We utilized a novel dynamic cardiopulmonary CT approach to explore cardiac dysfunction during COPD exacerbation. Method(s): Forty-five patients with acute exacerbation of COPD underwent low radiation contrast enhanced 256-slice dynamic cardiac function CT. The additional diagnostic yield of dynamic CT was compared to usual clinical care-history/examination/ECG/CXR. Result(s): Only 20% of the population had known IHD. CT identified significant coronary artery calcification in 53.3% (p = 0.001). Amongst those with extensive plaque (AU > 400, n = 16) 50% were not taking antiplatelets or statins, and only 6.3% were taking beta-blockers. Acute LV dysfunction (EF < 55%) was identified in 15.6% by CT compared to 6.7% on clinical grounds (p = 0.19). CT identified RV dysfunction (EF < 45%) in 27.9% v 15.6% on clinical grounds (p = 0.2). Pulmonary artery distensibility was significantly impaired (cross-sectional area change <15%) in 34.1% with only 11.1% having clinically diagnosed pulmonary hypertension. The study population had severe underlying emphysema-mean emphysema index 15.5% +/- 12.9(SD). Median radiation dose was low at 3.6 mSV. Conclusion(s): Dynamic CT frequently identifies 'clinically occult' cardiac dysfunction in COPD exacerbation. This technique can performsimultaneous heart and lung evaluation at low radiation dose to optimize patient selection for therapeutic intervention.

Background: Cardiac computed tomography (CCTA) has excellent negative predictive value for exclusion of significant coronary disease. Recent advances in 320-slice multi-detector scanner technology (Aquilion ONE VISION Edition, Toshiba Medical Systems) has increased gantry rotation speed (from 0.35 to 0.275 s/revolution) with the potential for enhanced temporal resolution. We examined the effect of this change on radiation dose and image quality. Method(s): Between July 2011 and February 2013 we prospectively analysed radiation dose and its determinants in two cohorts of consecutive patients (n = 211) undergoing CCTA immediately pre-and post implementation of increased rotation speed. Baseline characteristics (age, sex, BMI, HR) were similar between cohorts. Image quality was assessed by number of segments deemed uninterpretable by co-reporting cardiologists and radiologists using the AHA 17-segment coronary artery model. Summary statistics were compared as means or medians (S.D. or interquartile range). Distribution of diagnostic and non-diagnostic segments between cohorts were compared by chi square test. Comparison of radiation dose between cohorts was by independent samples median test. Result(s): There was no significant change in median radiation dose (DLP) from 155.80mGycm (IQR 99.20-264.95) to 181.15mGycm (IQR 121.75-288.48) in cohort 1 versus 2 (P = 0.30). In cohort 1 compared with cohort 2 there were 47 non-diagnostic segments with 25 were due to motion artefact compared with 25 and six respectively in cohort 2 (both P < 0.005). Conclusion(s): Increased gantry rotation speed has been associated with significant reduction in non-interpretable coronary artery segments due to motion artefact without any significant increase in radiation dose.

Left atrial occlusion devices are a recognized treatment option in patients with difficult to treat atrial fibrillation or intolerance to warfarin therapy. There are an increasing number of devices on the market, and good quality preoperative imaging is crucial to assess the feasibility of the procedure and help plan the occlusion. Electrocardiography-gated cardiac CT is ideal for this purpose as the high spatial and temporal resolution allow accurate measurements and reformats in multiple planes. As the imaging specialist reporting the CT may not necessarily be the interventionalist performing the implantation, this review will illustrate the important points in reporting the preimplant CT. The expected postoperative appearances and potential complications will also be described.Copyright © 2015 Society of Cardiovascular Computed Tomography.

Background: Few studies have evaluated the suitability of CCTA as a gatekeeper for invasive coronary angiography (ICA) by assessing its accuracy to detect functional stenosesandpredict need for revascularisation. We sought to determine the accuracy of 320-detector-row coronary computed tomography angiography (320-CCTA) to detect functional stenoses using fractional flow reserve (FFR) as reference standard and to predict the need for revascularisation in stable coronary artery disease. Method(s): 115 patients (230 vessels) underwent 320- CCTA, ICA, quantitative coronary angiography (QCA) and FFR assessment and were followed for 18 months. Diameter stenosis on ICA and CCTA were assessed by consensus by two observers and significant stenosis defined as>=50%. FFR<=0.8 indicated functionally significant stenoses. Result(s): 320-CCTA had 94% sensitivity and 94% negative predictive value (NPV) for FFR<=0.8. Overall accuracy was 70%, specificity 54% and positive predictive value 65%. On receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) for CCTA to predict FFR<=0.8 was 0.74 which was comparable with QCA (0.71, P = 1.0) and visual ICA 0.81 (P = 0.2) respectively. The absence of a significant stenosis on 320-CCTA was associated with a 6% revascularisation rate. 320-CCTApredicted the need for revascularisation with an AUC of 0.71, which was comparable with QCA (0.69, P = 1.0) and visual ICA (0.77, P = 0.5). Conclusion(s): 320-CCTA has excellent sensitivity and NPV for functional stenoses and therefore can act as an effective gatekeeper to defer ICA and revascularisation. Similar to ICA, 320-CCTA however lacks specificity for functional stenoses and has moderate accuracy to predict need for revascularisation.

Background: The comparative image quality of computed tomographic coronary angiography (CTCA) from second generation 320-detector-row CT in patients with high heart rates at the time of imaging has not been reported. Aim(s): To compare image quality of second generation versus first generation 320-detector-row CTCA in patients with heart rate >=65 bpm. Method(s): Consecutive subjects in a single institution cardiac CT service scanned with high heart rates using the Toshiba AQUILION ONE VISION 320-CTCA were studied (Group 1). Age and heart rate matched subjects who had undergone 320-multi-detector CTCA on the first-generation Toshiba AQUILION ONE at the same institution were retrospectively identified (Group 2). Image quality for each coronary artery segment was assessed by two blinded CT angiographers using the five point Likert scale (1-poor, 2-adequate, 3-good, 4-very good and 5-excellent). Result(s): A total of 529 coronary segments in 46 subjects (24 in group 1) were studied. Groups did not differ by age (52.3 vs. 52.7 years, P = 0.911), heart rate during acquisition (68 vs 68.5 bpm, P = 0.636), or body mass index (29.6 vs. 30.1, P = 0.848). The use of lower tube potential (100 kV) for imaging was greater in group 1 (16 vs. 5 subjects, P = 0.003). Scan image quality was superior in group 1 (mean 4.1 vs. 3.5, P = 0.018) and was associated with lower radiation (2.8 vs. 7.5mSv, P = 0.019). Conclusion(s): Second generation 320-detector-rowCTCA is capable of imaging in subjects presenting with elevated heart rate without loss of image quality and with a lower radiation exposure compared to first generation 320-detector-row CTCA.

Background: Coronary-computed-tomographyangiography (CTA) has limited specificity for predicting functionally significant stenoses. Contrast attenuation along an arterial lesion may provide assessment of functional significance of coronary stenosis. 320- detector-row CT, enabling near isophasic, single-beat imaging of the entire coronary tree may be ideal for transluminal-attenuation-gradient (TAG) and contrastopacification- difference (CO-difference) assessment. Method(s): We studied TAG320 and CO-difference with 320-detector-row CT on consecutive patients undergoing invasive-coronary-angiography and FFR for stable chest pain. The luminal-radiological-contrast-attenuation (Hounsfield-Units, HU) was measured at 5-mm intervals along the artery from ostium to a distal level where the cross-sectional-area fell below 2.0 mm2. TAG320 was defined as the linear-regression-coefficient between luminal attenuation and axial distance. CO difference was defined as mean difference in radiologicalcontrast- attenuation pre and post-stenosis. Functionallysignificant- coronary-stenosis was defined as <=0.8 on FFR. Result(s): In 54 patients (age 62.7+/-8.7 years, 35 males, 78 vessels), TAG320 in FFR-significant-vessels was significantly lower when compared with FFR non-significantvessels [-21 (-27;-16) vs -11 (-16;-3) HUs/10mm, P < 0.001]. On receiver-operating-characteristic (ROC) analysis, the AUC for TAG320 predicting FFR <=0.8 was 0.8 (0.7-0.9) compared to CTA 0.8 (0.72-0.88) and COdifference 0.74 (0.62-0.87).The combinedTAG320 and CTA assessment had an area-under-the-curve (AUC) of 0.88. There was incremental value of adding TAG320 to CTA assessment for detection of significant FFR by integrated discrimination improvement (IDI) index (0.11, P = 0.002). Conclusion(s): TAG320 and CO-difference are novel noninvasive techniques for detecting functionally significant coronary stenoses. Combined TAG320 and CTA assessment may have incremental predictive value over CTA alone for detecti

Objectives The goal of this study was to compare the diagnostic accuracy of combined computed tomography perfusion (CTP) + computed tomography angiography (CTA), transluminal attenuation gradient by 320-detector row computed tomography (TAG320) + CTA, and CTP + TAG320 + CTA (multidetector computed tomography-integrated protocol [MDCT-IP]) assessment in predicting significant fractional flow reserve (FFR). Background CTA has limited specificity for predicting functionally significant stenoses. Novel CT techniques, including adenosine stress CTP and TAG320, may improve the diagnostic accuracy of CTA. Methods CTA, CTP, and TAG320 were assessed using 320-detector row MDCT. Patients who underwent CTA, CTP, and FFR assessment on invasive coronary angiography were included. CTP was assessed using the visual perfusion assessment. TAG320 was defined as the linear regression coefficient between luminal attenuation and axial distance. A TAG320 cutoff value of -15.1 HU/10 mm as previously described was defined as significant. Functionally significant coronary stenosis was defined as FFR >=0.8. Results The cohort included 75 patients (age 64.1 +/- 10.8 years, 52 men) and 44 (35%) FFR-significant vessels. In 127 vessels, CTA predicted FFR-significant stenosis with 89% sensitivity and 65% specificity compared with MDCT-IP, which showed 88% sensitivity and 83% specificity. In 97 vessels in which the results of all techniques were available, TAG320 + CTA (area under the curve [AUC] = 0.844) and CTP + CTA (AUC = 0.845) had comparable per-vessel diagnostic accuracy (p = 0.98). The diagnostic accuracy of MDCT-IP (AUC = 0.91) was superior to TAG320 + CTA or CTP + CTA (p = 0.01). Conclusions In vessels without significant calcification or artefact, TAG320 + CTA and CTP + CTA provide comparable diagnostic accuracy for functional assessment of coronary artery stenosis. MDCT-IP may provide the best diagnostic accuracy for functional assessment of coronary artery stenosis. © 2014 by the Amer

Objective The purpose of this study was to assess the diagnostic accuracy of TAG320 in predicting functional stenosis severity evaluated by fractional flow reserve (FFR). Background(s): Coronary computed tomography angiography (CCTA) has limited specificity for predicting functionally significant stenoses. Recent studies suggest that contrast gradient attenuation along an arterial lesion, or transluminal attenuation gradient (TAG), may provide assessment of functional significance of coronary stenosis. The use of 320-detector row computed tomography (CT), enabling near isophasic, single-beat imaging of the entire coronary tree, may be ideal for TAG functional assessment of a coronary arterial stenosis. Method(s): We assessed the diagnostic accuracy of TAG320 using 320-row CCTA with FFR for the evaluation of functional stenosis severity in consecutive patients undergoing invasive coronary angiography and FFR for stable chest pain. The luminal radiological contrast attenuation (Hounsfield units [HU]) was measured at 5-mm intervals along the artery from ostium to a distal level where the cross-sectional area decreased to <2.0 mm2. TAG320 was defined as the linear regression coefficient between luminal attenuation and axial distance. Functionally significant coronary stenosis was defined as <=0.8 on FFR. Result(s): In our cohort of 54 patients (age 62.7 +/- 8.7 years, 35 men, 78 vessels), TAG320 in FFR-significant vessels was significantly lower when compared with FFR nonsignificant vessels (-21 [-27; -16] vs. -11 [-16; -3] HU/10 mm, p <= 0.001). On receiver-operating characteristic analysis, a retrospectively determined TAG320 cutoff of -15.1 HU/10 mm predicted FFR <=0.8 with (a bootstrapped resampled) a sensitivity of 77%, specificity of 74%, positive predictive value of 67%, and negative predictive value of 86%. The combined TAG320 and CCTA assessment had an area under the curve of 0.88. There was incremental value of adding TAG320 to CCTA assessment for detection of

Objectives: To determine the accuracy of 320-row multidetector coronary computed tomography angiography (M320-CCTA) to detect functional stenoses using fractional flow reserve (FFR) as the reference standard and to predict revascularisation in stable coronary artery disease. Method(s): One hundred and fifteen patients (230 vessels) underwent M320-CCTA and FFR assessment and were followed for 18 months. Diameter stenosis on invasive angiography (ICA) and M320-CCTA were assessed by consensus by two observers and significant stenosis was defined as >=50 %. FFR <=0.8 indicated functionally significant stenoses. Result(s): M320-CCTA had 94 % sensitivity and 94 % negative predictive value (NPV) for FFR <=0.8. Overall accuracy was 70 %, specificity 54 % and positive predictive value 65 %. On receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) for CCTA to predict FFR <=0.8 was 0.74 which was comparable with ICA. The absence of a significant stenosis on M320-CCTA was associated with a 6 % revascularisation rate. M320-CCTA predicted revascularisation with an AUC of 0.71 which was comparable with ICA. Conclusion(s): M320-CCTA has excellent sensitivity and NPV for functional stenoses and therefore may act as an effective gatekeeper to defer ICA and revascularisation. Like ICA, M320-CCTA lacks specificity for functional stenoses and only has moderate accuracy to predict the need for revascularisation. Key Points: * Important information about the heart is provided by 320-row multidetector CT coronary angiography (M320-CCTA). * M320-CCTA accurately detects and excludes functional stenoses determined by fractional flow reserve (FFR). * Non-significant stenoses on M320-CCTA associated with fewer cardiac events and less revascularisation. * M320-CCTA may act as a gatekeeper for invasive angiography and inappropriate revascularisation. * Like ICA, M320-CCTA only has moderate accuracy to predict vessels requiring revascularisation. © 2013 European So

Purpose: Surgical resection offers the best curative potential for lung cancer, and accurate staging is crucial in predicting operability and surgical planning.1,2We aimed to use Dynamic wide field of view 4D CT to assess differential motion between lung cancer and an adjacent structure for determining surgical resectability. Methods and Materials: Fifteen subjects with biopsy proven lung carcinoma, no evidence of metastasis, and suspected invasion of an adjacent structure in staging CT underwent respiratory dynamic 4D CT. Imaging was done using 320-slice MDCT (Aquilion ONE, Toshiba Medical Systems, Tochigi, Japan) with z-axis coverage of 16 cm.3 The principle was to undertake a CT volume scan without table motion and applying patient motion in the form of inspiration-expiration, to produce a 4D dataset. Acquisition was initiated in full expiration and terminated after two respiratory cycles, producing six volume image datasets per second. Intravenous contrast was administered for lesions adjacent to vascular structures. The images were assessed, in multiple planes, for presence or absence of differential motion, defined as disparate movement (either in direction and/or in qualitative speed) between tumor and adjacent chest wall/mediastinal structure. Previous staging was altered where necessary according to TNM classification.4 Results: Overall there was excellent correlation between preoperative 4D CT and surgical findings. Of the fifteen cases assessed, pre-surgical assessment of lack of differential movement and possible tethering was made in five, which were all surgically confirmed. Differential motion and hence absence of invasion was diagnosed in 10 subjects, resulting in significant down staging directly attributable to 4D CT. This was substantiated surgically in nine while the remaining one was a false negative study, the tumour adjacent to the SVC being unresectable at surgery. However, on review of his imaging, though most of the tumour confirmed differe

Cardiomyopathies are increasingly being detected on both routine and non-routine imaging. Furthermore, the diagnosis of cardiomyopathy is changing from the traditional method of clinical presentation and cardiac morphology to a quantifiable method based on both cardiac morphology and function. With cardiac magnetic resonance imaging, coronary computed tomography and nuclear medicine increasingly being utilized along with echocardiography in the diagnostic process, it is important for the radiologist to be aware of the relevant criteria in formulating a diagnosis. We aim to provide an overview of the imaging characteristics of the most commonly encountered cardiomyopathies. © 2013 Elsevier Ireland Ltd.

Introduction: Reference values for measurements of the aortic root have been obtained by Transthoracic echocardiography (TTE), and TTE is used for the detection, follow-up and surgical decision making in aortic disease because of the outcome data that have been published with this approach. Contemporary gated CT studies provide a 3 dimensional data set offering the potential for more precise measurement of the aorta, although it is unclear which measurement is most interchangeable with TTE. Objective(s): We aim to compare various CT based measurements of the aortic root with those from echocardiograms to determine which is most consistent with echocardiography. Method(s): 40 patients with dilatation of the aortic root on echocardiography who also underwent prospective gated cardiac CT scan less than 4 months apart were evaluated. TTE images were evaluated by a blinded reader measuring the max antero-posterior (AP) diameter of the trans-sinus region with calipers from the PLAX view,utilising inner edge to inner edge method. CT images were evaluated by a separate reader who manipulated data using the "double oblique" technique to create an on-axis en face view of the aortic root. Measurements included the distance from each aortic sinus to their opposing commissure (S-C) and also the trans-sinus dimensions (S-S). Additionally CT images were manipulated to create a long axis view similar to the view obtained from echocardiography (CTLAX) where the maximum AP diameter was obtained. Result(s): All CT related measurements demonstrated good correlation with echocardiographic measurements. CT sinus to sinus distance measurements were consistently larger than echo, while the average S-C was significantly smaller. The measurements showing no significant difference with TTE were the maximal S-C and CTLAX aortic root measurement, although the S-C had a slightly better correlation.(Table Presented) Conclusion(s): In patients with aortic dilatation undergoing gated CT scanning, d

Objectives: We sought to determine the accuracy of combined coronary computed tomography angiography (CTA) and computed tomography stress myocardial perfusion imaging (CTP) in the detection of hemodynamically significant stenoses using fractional flow reserve (FFR) as a reference standard in patients with suspected coronary artery disease. Background(s): CTP can be qualitatively assessed by visual interpretation or quantified by the transmural perfusion ratio determined as the ratio of subendocardial to subepicardial contrast attenuation. The incremental value of each technique in addition to coronary CTA to detect hemodynamically significant stenoses is not known. Method(s): Forty symptomatic patients underwent FFR and 320-detector computed tomography assessment including coronary CTA and CTP. Myocardial perfusion was assessed using the transmural perfusion ratio and visual perfusion assessment. Computed tomography images were assessed by consensus of 2 observers. Transmural perfusion ratio <0.99 was used as the threshold for abnormal perfusion. FFR <=0.8 indicated hemodynamically significant stenoses. Result(s): Coronary CTA detected FFR-significant stenoses with 95% sensitivity and 78% specificity. The additional use of visual perfusion assessment and the transmural perfusion ratio both increased the specificity to 95%, with sensitivity of 87% and 71%, respectively. The area under the receiver-operating characteristic curve for coronary CTA + visual perfusion assessment was significantly higher than both coronary CTA (0.93 vs. 0.85, p = 0.0003) and coronary CTA + the transmural perfusion ratio (0.93 vs. 0.79, p = 0.0003). Per-vessel and per-patient accuracy for coronary CTA, coronary CTA + the transmural perfusion ratio, and coronary CTA + visual perfusion assessment was 83% and 83%, 87% and 92%, and 92% and 95%, respectively. Conclusion(s): In suspected coronary artery disease, combined coronary CTA + CTP identifies patients with hemodynamically significant sten

Aims: Adenosine stress computed tomography myocardial perfusion imaging (CTP) is an emerging non-invasive method for detecting myocardial ischaemia. Its value when compared with fractional flow reserve (FFR), a highly accurate index of ischaemia, is unknown. Our aim was to determine the diagnostic accuracy of CTP and its incremental value when used with computed tomography coronary angiography (CTA) for detecting ischaemia compared with FFR. Methods and Results: Forty-two patients (126 vessel territories), who had at least one <50% angiographic stenosis on invasive angiography considered for non-urgent revascularization, were included and underwent FFR and CT assessment, including CTP, delayed contrast enhancement scan and CTA all acquired using 320-detector row CT, and prospective ECG gating. Fractional flow reserve was determined in 86 territories subtended by vessels with <50% stenosis upon visual assessment. Fractional flow reserve <=0.8 was considered to indicate significant ischaemia. Computed tomography myocardial perfusion imaging correctly identified 31/41 (76%) ischaemic territories and 38/45 (84%) non-ischaemic territories. Per-vessel territory sensitivity, specificity, positive, and negative predictive values of CTP were 76, 84, 82, and 79%, respectively. The combination of a <50% stenosis on CTA and perfusion defect on CTP was 98% specific for ischaemia, while the presence of <50% stenosis on CTA and normal perfusion on CTP was 100% specific for exclusion of ischaemia. Mean radiation for CTP and combined CT was 5.3 and 11.3 mSv, respectively. Conclusion(s): Computed tomography myocardial perfusion imaging is moderately accurate in identifying perfusion defects associated with ischaemia as assessed by FFR in patients considered for revascularization. In territories, where CTA and CTP are concordant, CTA/CTP is highly accurate in the detection and exclusion of ischaemia. This is achievable with acceptable radiation exposure using 320-detector row CT and p

Accessory left atrial appendages and atrial diverticula have an incidence of 10-27%. Their association with atrial fibrillation needs to be confirmed. This study determined the prevalence, number, size, location and morphology of accessory left atrial appendages/atrial diverticula in patients with atrial fibrillation compared with those in sinus rhythm. A retrospective analysis of 47 consecutive patients with atrial fibrillation who underwent 320 multidetector Coronary CT angiography (CCTA) was performed. A random group of 47 CCTA patients with sinus rhythm formed the control group. The presence, number, size, location and morphology of accessory left atrial appendages and atrial diverticula in each group were analysed. Twenty one patients had a total of 25 accessory left atrial appendages and atrial diverticula in the atrial fibrillation group and 22 patients had a total of 24 accessory left atrial appendages and atrial diverticula in the sinus rhythm group. Twenty-one atrial diverticula were identified in 19 patients in the atrial fibrillation group and 19 atrial diverticula in 17 patients in the sinus rhythm group. The mean length and width of accessory left atrial appendage was 6.9 and 4.7 mm, respectively in the atrial fibrillation group and 12 and 4.6 mm, respectively, in the sinus rhythm group, P = ns (not significant). The mean length and width of atrial diverticulum was 4.7 and 3.6 mm, respectively in the atrial fibrillation group and 6.2 and 5 mm, respectively in the sinus rhythm group (P = ns). Eighty-four%and 96% of the accessory left atrial appendages/atrial diverticula in the atrial fibrillation and sinus rhythm groups were located along the right anterosuperior left atrial wall. Accessory left atrial appendages and atrial diverticula are common structures with similar prevalence in patients with atrial fibrillation and sinus rhythm. © Springer Science+Business Media, B.V. 2011.

Background: CT myocardial perfusion imaging is an emerging CT application using density measurements of contrast-enhanced left ventricular (LV) myocardium. Objective(s): Using a 320-MDCT we have consistently observed lower Hounsfield unit (HU) values in the lateral LV myocardium, potentially mimicking perfusion defects. This study aimed to evaluate contrast-enhancement patterns of the LV myocardium in normal studies. Method(s): Twenty-one clinical cases with normal coronary MDCT-based angiography findings, as determined by 2 qualified readers, were selected for retrospective evaluation. Using 8 identically sized and positioned ROIs, the HU measurements were recorded from short axis axial reconstructions through the LV myocardium in middle, apical, and basal locations. Scans were acquired on a 320-slice MDCT unit. Result(s): The middle short axis location demonstrated HU densities of 79.4 (range 42.3-162.7) in the lateral myocardial wall (regions 2, 3, and 4) compared with 103.9 (range 11.4-159.6) in the inferior, septal, and anterior walls (regions 1, 5, 6, 7, and 8; P < 0.001). HU densities for the basal slice were 82.3 (range 51.5-168.4) in the lateral wall compared with 94.9 (range 35.3-144) in the inferior, septal, and anterior walls (P < 0.001). In the apical location, HU densities were 79.9 (range 42.3-139.3) in the lateral wall compared with 100.9 (range 69.0-170.5) in the inferior, septal, and anterior walls (P < 0.001). Conclusion(s): Normal LV myocardial enhancement using a 320-slice MDCT demonstrates significantly lower densities in the lateral wall when compared with the anterior, septal, and inferior walls in patients with normal coronary vascular anatomy. Assessment of CT myocardial perfusion studies should therefore be undertaken with caution, to prevent misrepresenting these lower-density values in the LV lateral wall. © 2011.

Objectives: 320-slice computed tomography (CT) provides 3-dimensional and dynamic imaging, resulting in the ability to assess motion analysis between two adjacent structures (the 4th dimension). Differential movements between two adjacent structures would indicate there is no fixation between the two structures. Method(s): Eight patients with non-small-cell lung cancers located adjacent to vital structures (e.g. the great vessels, n=4) or chest wall (n=4) where conventional CT was unable to exclude local invasion, underwent dynamic 4-dimensional CT assessment. In four patients, the lung tumour was abutting the chest wall. The remaining patients included a patient with a large 14 cm left lower lobe cancer abutting the descending thoracic aorta who had previous pleurodesis; a patient with an apical right upper lobe 6 cm cancer with static imaging appearances suggestive of tumour invasion into the apex and mediastinal surface (superior vena cava) of the thorax; a patient with a 3.5 cm cancer which had a broad 2.5 cm base abutting the distal aortic arch; and a patient with a 14 cm left upper lobe cancer abutting the aortic arch, descending thoracic aorta and chest wall. Differential movements between the tumour and adjacent structure on 4-D CT was considered indicative of the absence of frank invasion. Result(s): Dynamic 4-D imaging revealed differential movements between the tumour and the adjacent structures in all cases suggesting the absence of overt malignant invasion. Intraoperative assessment confirmed resectability of the cancers in all eight patients. Conclusion(s): Dynamic 4-dimensional 320-slice CT is useful in the preoperative assessment of lung cancer direct invasion into adjacent structures and hence resectability.

Learning Objectives: The aim is to provide an overview of the cardiomyopathies (CM) which may be suspected and diagnosed on CCTA, both in the inpatient and outpatient. Main: Coronary computed tomographic angiography (CCTA) is an established tool for the investigation of chest pain. CCTA acquisition techniques can be varied according to the clinical indication whilst the overall aim being to maintain optimal imaging with lowest possible radiation exposure. Although the strength of CCTA is its very high negative predictive value for the exclusion of significant coronary artery disease, it also may provide important additional information on the presence of CM, which can coexist with various causes of chest pain including obstructive coronary artery disease. Furthermore, symptoms such as shortness of breath and chest pain that the clinician may suspect are secondary to coronary disease leading to investigation with CCTA, may be secondary to CM. We review several important types of CM including hypertensive CM, hypertrophic CM, dilated CM, left ventricular non compaction syndrome, arrythmogenic right ventricular complex, Takotsubo CM, that may be detected by CCTA, which are important for radiologists to identify given the implications for further management and prognosis. We also aim to review the imaging acquisition technique which will assist with cardiomyopathy evaluation.

Objective: This study sought to determine the accuracy of adenosine stress computed tomography myocardial perfusion imaging (CTP) using fractional flow reserve (FFR) as reference standard. We also sought to compare the relative accuracy of CTP and quantitative coronary angiography (QCA) against FFR. Method(s): 31 patients with at least one >=50% artery stenosis underwent invasive angiography (IA), FFR and CT protocol, which included prospectively ECG triggered CT coronary angiography, delayed enhanced acquisition and CTP performed on 320 slice CT. Images were interpreted by 2 independent blinded readers. 93 vessel territories including 66 which underwent FFR interrogation were included for analysis. Territories are defined as ischemic, if supplied by an artery with FFR <=0.8, and non ischemic, if supplied by an artery with <50% stenosis or FFR >0.8. Result(s): All patients (19 male, 64+/-8 years) completed the CT protocol with a mean radiation exposure of 11.5+/-4.1 mSv. CTP correctly identified 28/38 ischemic territories and 49/55 non ischemic territories. Sensitivity, specificity, and positive and negative predictive values of CTP for detecting ischemia were 74%, 89%, 82%, 83%, compared to QCA>=70% of 29%, 100%, 100%, and 67% respectively. Conclusion(s): CTP can accurately detect perfusion defects associated with ischemia as assessed by fractional flow reserve. This can be achieved with an acceptable radiation dose using prospectively ECG triggered acquisition. CTP appears to have a favourable relative accuracy compared against QCA in the detection for ischemia.

CT perfusion (CTP) has an important role in the acute management of stroke by confirming the diagnosis and providing quantification of infarct core and salvageable penumbra. The main limitation has been a limited scan volume. The newer multidetector 320 slice (MD320) scanners have a scan volume of 16 cm with the ability to cover the whole brain. It also has the ability to provide a dynamic CT angiogram (CTA) of the brain in the same acquisition. The aim of the study was to compare 4 cm vs 16 cm z-axis in the assessment of CTP. Retrospective non-randomised review of CTP carried out on MD320 scanner between 09/2008 and 01/2009 was undertaken. Two experienced readers reviewed the studies along with the 4 and 16 cm Z-axis CTP image data set. The outcome parameters assessed were extent of the original finding, additional findings and change to diagnosis. A total of 27 patients were reviewed, 14 patients were found to have abnormal CTP (mean age 58.1 years, 9 males and 5 females). The 16 cm z-axis increased the accuracy of infarct core in 78% and ischaemic penumbra quantification in 100% of the cases. It also diagnosed additional infarcts in the same vascular territory in 28% of cases and in a different vascular territory in 14%. The increased field of view with MD320 better defines the true extent of the infarct core and ischaemic penumbra. It also identified other areas of infarction that were not identified on the 4 cm Z-axis.

Background: Contemporary Emergency Department (ED) investigation of low-to-intermediate risk chest pain involves serial troponin measurement and subsequent stress testing. We sought to assess the impact on length of stay (LOS) of a CT-guided approach by comparing patients discharged after a single negative troponin and normal coronary CT angiogram (CCTA) with those discharged after serial troponin measurement on the basis of CCTA showing mild to moderate coronary artery disease. Method(s): 130 patients were included after we prospectively evaluated 161 consecutive patients who underwent 320-slice CCTA (dose-modulated retrospective electrocardiogram-triggering) after presenting to ED with low-to-intermediate risk ischaemic-type chest pain (TIMI 0-4) with normal initial troponin and electrocardiogram, and no known>50% coronary stenoses or previous revascularisation. Patients with no overt plaque or stenoses on CCTA were discharged after a single negative troponin, whilst patients with <50% stenoses were discharged after repeat negative 6-h troponin. Patients with <50% stenoses were admitted for invasive angiography and excluded from analysis. Result(s):Meanagewas59 +/-11years(62%male).53(41%) patients had no overt plaque or stenoses and were discharged after a single troponin.77(59%) patients had<50% stenoses and were discharged after repeat troponin. Mean ED LOS for patients discharged after a single troponin was 389 min (+/-20) compared to 576 min (+/-21) for patients requiring repeat troponin (p< 0.01). Conclusion(s): Discharging patients after a single negative troponin and normal 320-slice CCTA significantly reduces ED LOS compared to patients requiring serial troponin measurement, illustrating the benefit of a CCTA-guided approach to investigation.

Introduction: Patient specific factors such as high heart rate (HR) and body mass index (BMI) may influence cardiac CT (CCT) image quality. We aim to evaluate the influence of BMI on image quality of coronary 320-multidetector computed tomography (MDCT) in patients with high HR above 65 beats/min (bpm). Method(s): A retrospective analysis was performed. Patients were divided into different HR (? 65 bpm, n = 30 and > 65 bpm, n = 30) and BMI groups (18.5 - 24.99, 25.0 - 29.99 and ? 30.0). Two reviewers were blinded to the patient groups and evaluated CCT images performed on 320-MDCT using a workstation (Vitrea Fx Workstation, Vital Images). The image quality was scored subjectively as 1 (excellent quality; diagnostic), 2 (suboptimal quality; diagnostic) or 3 (poor quality; non-diagnostic). 15-segment coronary arterial tree was utilized. Anatomically absent segments were excluded from analysis. Groups were compared using Mann-Whitney U or Chisquare tests. Result(s): There was no statistical difference in the demographic characteristics of the patient groups (p > 0.05). The majority of coronary artery images were of diagnostic quality (scores of 1 and 2) in patients with HR ? 65 bpm independent of BMI; 97.0%, 97.2% and 96.3% were of diagnostic quality for BMI groups 18.5 - 24.99, 25.0 - 29.99 and ? 30.0, respectively (p > 0.05). For patients with HR > 65 bpm, we noted no significant difference in diagnostic quality of images as BMI increases; 100%, 96.3% and 91.2% were of diagnostic quality for BMI groups 18.5 - 24.99, 25.0 - 29.99 and ? 30.0, respectively (p > 0.05). However, our study was limited by the number of patients retrospectively analyzed. Conclusion(s): Our initial experience suggests that high BMI does not significantly affect image quality of coronary 320-MDCT in patients with HR > 65 bpm. The vast majority of coronary artery images obtained using 320-MDCT were of diagnostic quality independent of BMI. Due to our relatively small sample sizes, we propose la

Introduction: Left atrial appendages (LAA) and diverticula (AD) have an incidence of 10-27% on coronary CT angiography(CCTA). AD/LAA are associated with supraventricular arrhythmias and electric dissociation. A recent report confirmed ectopic activity within LAA in a patient with Atrial fibrillation(AF). The study aimed to determine the prevalence, number, size, location and morphology of LAA/AD in patients with AF compared with those in sinus rhythm(SR). Method(s): A retrospective analysis of 47 consecutive patients with AF who underwent 320 multidetector CCTA was performed. A random group of 47 CCTA patients with SR formed the control group. The presence, number, size, location and morphology of LAA and AD in each group were analysed. Result(s): Twenty one patients had 25 LAA /AD in the AF group and 22 patients had 24 LAA /AD in the SR group. N=4 and N=5 patients had LAA in the AF and SR groups, respectively. Twenty-one AD were identified in 19 patients in the AF group and 19 AD in 17 patients in the SR group. The median length and width of accessory left atrial appendage in the AF group was 6.9 (5-18) mm and 4.7 (2.3-9)mm respectively and in the SR group these measurements were 12mm (5.2-25) and 4.6 (3.8-7)mm respectively, p=0.41 (length) and 0.99 (width). The median (ranges) length and width of atrial diverticula in the AF group was 4.7 (2.2-11.3)mm and 3.6 (2.1-5.4) mm respectively and in the SR group these measurements were 6.2 (2-13) mm and 5 (1- 8.5) mm respectively, p=0.22 (length) and 0.26(width).Eighty-four % and 96% of the LAA/AD in the AF and SR groups were located along the right anterosuperior left atrial wall. No thrombus was detected in either group. Conclusion(s): Accessory left atrial appendages and diverticula are common structures readily detected with the advent of multidetector CT(MDCT) scanners. Though ectopic activity has been demonstrated within these structures, in our cohort of 47 patients with AF we demonstrated similar prevalence of the

Introduction: This study is a retrospective evaluation of our initial experience using 320 slice CT coronary angiography (320-CCT) for investigation of coronary artery disease (CAD) in patients in atrial fibrillation (AF) at the time of scanning. Positive 320-CCT findings of CAD were correlated against the occurrence of a major adverse coronary event (MACE) including death, myocardial infarction or coronary artery revascularisation in the 6 months following 320-CCT. Method(s): Our population consisted of forty-six consecutive patients in AF at the time of undergoing 320-CCT. 320-CCT findings of CAD were graded from the dual reports signed by either a level two or level three (American College of Cardiology) radiologist and cardiologist respectively. Diagnostic quality of the study and any co-existing pathology have also been recorded. Results were compared against medical records and a targeted patient history for the presence or absence of a MACE in the 6 months following CCT. Result(s): Of the 46 patients, 36 had 320-CCT diagnosed CAD. 8 had a MACE in the 6 months following 320-CCT, all of which had 320-CCT diagnosed coronary artery disease. None of the patients with no CAD on 320-CCT went on to MACE. Conclusion(s): In patients with AF, 320-CCT has demonstrated high accuracy with regard to correlation with MACE in the 6 months following the procedure. Our initial experience suggests that 320-CCT has a high diagnostic accuracy with regard to clinical utility in assessing CAD in patients with AF.

Introduction: CT Myocardial Perfusion imaging is an emerging CT application that uses density measurements of the contrast enhanced Left Ventricular (LV) myocardium. Consistently we have observed lower CT densities in the lateral LV myocardium potentially mimicking perfusion defects. This study aims to evaluate contrast enhancement patterns of the LV myocardium in normal patients. Method(s): Twenty one normal coronary CT Angiography studies, as determined by two qualified readers, were randomly selected for evaluation. Five millimetre contiguous MPR series were generated covering the LV myocardium in the short axis. The middle slice was selected as well as a slice twenty millimetres towards the apex and base. Hounsfield unit measurements were recorded for each slice using identically sized and positioned rectangular regions of interest (ROI's) as displayed in Figure 1. CT Densities (median, ranges) at either the basal, mid and apical slices were compared using Mann Whitney U tests (SPSS, V 16). A p-value of < 0.05 was afforded significance. Result(s): The middle short axis slice demonstrated CT densities of 79.4 (42.3 - 162.7) in the lateral myocardial wall (regions 2,3,4) compared to 103.9 (11.4 - 159.6) in the posterior, septal and anterior walls (regions 1, 5,6,7,8; p <0.001). CT densities for the basal slice were 82.3 (51.5 - 168.4) in the lateral wall compared to 94.9 (35.3 - 144) in the posterior, septal and anterior walls (p <0.001). In the apical slice CT densities were 79.9 (42.3 - 139.3) in the lateral wall compared to 94.9 (35.3 - 144) in the posterior, septal and anterior walls (p <0.001). Conclusion(s): Normal LV myocardial enhancement using a 320 slice CT demonstrates lower CT densities of statistical significance in the lateral wall when compared to the anterior, septal and posterior wall regions in the apical, mid or basal short axis locations. Assessment of the LV myocardium in CT perfusion studies should therefore be undertaken with caution, to pre