John H. Reid

Acute right ventricular dilatation: a new helical CT sign of massive pulmonary embolism

UNLABELLED Acute right heart failure is a principal cause of circulatory collapse and death in patients with massive pulmonary embolism (PE). The purpose of this study was to investigate if helical computed tomography (CT) could contribute to the assessment of the right ventricle (RV) in those with massive PE. Over an 8-month period 79 helical CT pulmonary angiograms were performed to investigate suspected PE. Emboli were demonstrated in 28 (35%) patients and seven (9%) were considered to have had a major thromboembolic event. The CT scans of all patients were evaluated using parameters derived in the axial plane (maximum minor axis RV and LV dimensions, RV:LV minor axis ratio and RV wall thickness). Acute right ventricular dilatation with an RV:LV ratio> 1.5:1 (range 1.6:1-2.3:1, mean 2:1) was found in all seven patients who had sustained major PE. In the remaining group of 21 with lesser degrees of embolism no patient had an RV:LV ratio > 1.1:1 (range 0.8-1.1, mean 1.0). To our knowledge, this CT sign has not been described before. CONCLUSION Helical CT can identify acute RV dilatation in addition to making the primary diagnosis in patients with massive PE. This observation may help identify those at greatest risk of a second fatal event and facilitate therapeutic strategy.

Progressive coronary calcification despite intensive lipid-lowering treatment: a randomised controlled trial

Objectives: To evaluate the effect of intensive lipid-lowering treatment on coronary artery calcification in a substudy of a trial recruiting patients with calcific aortic stenosis. Methods: In a double blind randomised controlled trial, 102 patients with calcific aortic stenosis and coronary artery calcification were randomly assigned by the minimisation technique to atorvastatin 80 mg daily or matched placebo. Coronary artery calcification was assessed annually by helical computed tomography. Results: 48 patients were randomly assigned to atorvastatin and 54 to placebo with a median follow up of 24 months (interquartile range 24–30). Baseline characteristics and coronary artery calcium scores were similar in both groups. Atorvastatin reduced serum low density lipoprotein cholesterol (−53%, p < 0.001) and C reactive protein (−49%, p < 0.001) concentrations whereas there was no change with placebo (−7% and 17%, p > 0.95 for both). The rate of change in coronary artery calcification was 26%/year (0.234 (SE 0.037) log arbitrary units (AU)/year; n  =  39) in the atorvastatin group and 18%/year (0.167 (SE 0.034) log AU/year; n  =  49) in the placebo group, with a geometric mean difference of 7%/year (95% confidence interval −3% to 18%, p  =  0.18). Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r  =  0.05, p  =  0.62). Conclusion: In contrast to previous observational studies, this randomised controlled trial has shown that, despite reducing systemic inflammation and halving serum low density lipoprotein cholesterol concentrations, statin treatment does not have a major effect on the rate of progression of coronary artery calcification.

Aortic Valve Calcification on Computed Tomography Predicts the Severity of Aortic Stenosis

AIM Incidental aortic valve calcification is often detected during computed tomography. The aim was to compare the severity of valvular stenosis and calcification in patients with aortic stenosis. MATERIALS AND METHODS One hundred and fifty-seven patients aged 68+/-11 years (range: 34-85) with aortic valve stenosis underwent multislice helical computed tomography and Doppler echocardiography performed by independent, blinded observers. The aortic valve calcium score was determined using automated computer software calibrated with a phantom. RESULTS Doppler echocardiography demonstrated a post-valve velocity of 3.45+/-0.66 m/s and a peak gradient of 49+/-11 mmHg. Computed tomography showed excellent reproducibility and the median aortic valve calcium score was 5858 AU (interquartile range, 1555-14,596). The computed tomography aortic valve calcium score positively correlated with the Doppler post-valve velocity and peak gradient (r=0.54, p<0.0001 for both) of the aortic valve. All patients with severe aortic stenosis had a calcium score of >3700 AU. CONCLUSION Calcification of the aortic valve is closely associated with the severity of aortic stenosis, and heavy calcification suggests the presence of severe aortic stenosis that requires urgent cardiological assessment. Patients with lesser degrees of aortic valve calcification should be screened for aortic stenosis and monitored for disease progression.

Is the lung scan alive and well? Facts and controversies in defining the role of lung scintigraphy for the diagnosis of pulmonary embolism in the era of MDCT

PurposeThe last decade has seen a changing pattern of utilization of multidetector CT (MDCT) versus lung perfusion scintigraphy in the investigation of pulmonary venous thromboembolism (VTE). In response to this the International Atomic Energy Agency (IAEA) determined that the subject required an overview.MethodThe IAEA has invited a group of five specialists in the relevant fields to review the current status and optimum role of scintigraphy, to explore some of the facts and controversies surrounding the use of both modalities and to make recommendations about the continued role of nuclear medicine for the investigation of pulmonary embolism. This paper identifies the relative merits of each technique, highlights benefits, focuses on complementary roles and seeks a nonadversarial symbiosis.ConclusionThe consultants reached a consensus that the continued use of scintigraphy for diagnosis of thromboembolic disease is recommended, particularly in scenarios where scintigraphy confers specific benefits and is complementary to MDCT.

Iterative reconstruction and individualized automatic tube current selection reduce radiation dose while maintaining image quality in 320-multidetector computed tomography coronary angiography

Aim To assess the effect of two iterative reconstruction algorithms (AIDR and AIDR3D) and individualized automatic tube current selection on radiation dose and image quality in computed tomography coronary angiography (CTCA). Materials and methods In a single-centre cohort study, 942 patients underwent electrocardiogram-gated CTCA using a 320-multidetector CT system. Images from group 1 (n = 228) were reconstructed with a filtered back projection algorithm (Quantum Denoising Software, QDS+). Iterative reconstruction was used for group 2 (AIDR, n = 379) and group 3 (AIDR3D, n = 335). Tube current was selected based on body mass index (BMI) for groups 1 and 2, and selected automatically based on scout image attenuation for group 3. Subjective image quality was graded on a four-point scale (1 = excellent, 4 = non-diagnostic). Results There were no differences in age (p = 0.975), body mass index (p = 0.435), or heart rate (p = 0.746) between the groups. Image quality improved with iterative reconstruction and automatic tube current selection [1.3 (95% confidence intervals (CI): 1.2–1.4), 1.2 (1.1–1.2) and 1.1 (1–1.2) respectively; p < 0.001] and radiation dose decreased [274 (260–290), 242 (230–253) and 168 (156–180) mGy cm, respectively; p < 0.001]. Conclusion The application of the latest iterative reconstruction algorithm and individualized automatic tube current selection can substantially reduce radiation dose whilst improving image quality in CTCA.

The Effect of Graduated Compression Stockings on Long-term Outcomes After Stroke The CLOTS Trials 1 and 2

Background and Purpose— Most randomized controlled trials of venous thromboembolism prophylaxis have focused on reduction of deep vein thrombosis, predominantly asymptomatic deep vein thrombosis, detected on imaging. We aimed to estimate the effects of graduated compression stockings on venous thromboembolism events, survival, and functional status at 6 months after stroke. Methods— The CLOTS Trials adopted an international multicentre, parallel group design, with central randomization and a 1:1 treatment allocation. In CLOTS Trial 1, 2518 immobile stroke patients were allocated thigh-length graduated compression stockings or not, and in CLOTS trial 2, 3014 to thigh-length or below-knee graduated compression stockings. We measured vital status, Oxford Handicap Scale, and quality of life (EQ5D-3 L) at 6 months. Results— We compared survival in patients enrolled in Trials 1 and 2 with a Cox proportional hazards model, including variables included in our minimization algorithm. In both trials, allocation to thigh-length graduated compression stockings was associated with a very slight, but nonsignificant, increased hazard of death in the first 6 months (Trial 1: hazard ratio, 1.087; 95% confidence interval, 0.913–1.295; and Trial 2: hazard ratio, 1.037; 95% confidence interval, 0.892–1.205). There were no statistically significant differences in venous thromboembolism events, Oxford Handicap Scale, or EQ5D-3 L between the treatment groups in CLOTS Trials 1 or 2. Conclusions— Although underpowered to detect clinically important effects on long-term outcomes, our results effectively exclude a >10% relative reduction in the hazard of death within 6 months associated with the use of thigh-length stockings. No other long-term benefits were apparent.

Cardiac and coronary CT comprehensive imaging approach in the assessment of coronary heart disease

Cardiac CT is a rapidly advancing technology. Non-invasive CT coronary angiography is an established technique for assessing coronary heart disease with accuracy similar to invasive coronary angiography. CT myocardial perfusion imaging can now identify perfusion defects in animal models and humans. MRI is the current ‘gold standard’ for the assessment of myocardial viability, but it is now also possible to assess delayed enhancement by CT. This has led to the possibility of a ‘one-stop shop’ for cardiovascular imaging that would provide information on anatomy, function, perfusion and viability in one rapid diagnostic test at a radiation dose equivalent to contemporary nuclear medicine imaging. This review discusses the current status of ‘one-stop shop’ cardiac CT assessment, clinical utility and directions for future research.

Spiral CT in acute non-cardiac chest pain

AIM Spiral CT in acute non-cardiac chest pain is usually requested to diagnose aortic dissection but a spectrum of other cardiovascular diseases may simulate this. The purpose of this study was to assess the impact of spiral computed tomography (CT) in patients with suspected aortic dissection and to determine the nature and frequency of other disorders simulating it. METHODS Over a 26-month period, all patients undergoing CT for suspected acute aortic dissection were recruited. CT was performed using a standard protocol. The CT examinations and reports were reviewed along with other relevant imaging, clinical data, surgical findings and post-mortem results. The pattern of diagnoses and their associations were evaluated. RESULTS Seventy-six CT examinations were performed on 70 patients of whom 47 were male. The age of the patients ranged from 24 to 84. Seven patients had previously undergone cardiothoracic surgery. Twenty-four patients had normal CT findings; 46 patients (66%) had abnormal findings. Seventy-three significant pathologies were identified including thoracic aortic aneurysm (16 cases), aortic dissection (14 cases), acute intramural aortic haematoma (nine cases), aortic rupture (eight cases), atherosclerosis (four cases) and penetrating atheromatous ulcer (two cases), pulmonary embolus (four cases), pericardial disease (12 cases) and complications following surgery (three cases). The majority of patients had a life-threatening disease. Five patients without dissection had CT findings that explained clinical pulse deficits. CONCLUSION Sudden onset non-cardiac, non-pleuritic chest pain is common to several acute cardiovascular disorders. Patients have a high incidence of life-threatening disease. Of this group, classic aortic dissection is the most common diagnosis but comprises a minority of cases. Spiral CT is a reliable diagnostic test but requires conscientious technique for optimum sensitivity and accuracy. Most patients will have abnormal CT findings.

Observer variability in the assessment of CT coronary angiography and coronary artery calcium score: substudy of the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial

Introduction Observer variability can influence the assessment of CT coronary angiography (CTCA) and the subsequent diagnosis of angina pectoris due to coronary heart disease. Methods We assessed 210 CTCAs from the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial for intraobserver and interobserver variability. Calcium score, coronary angiography and image quality were evaluated. Coronary artery disease was defined as none (<10%), mild (10–49%), moderate (50–70%) and severe (>70%) luminal stenosis and classified as no (<10%), non-obstructive (10–70%) or obstructive (>70%) coronary artery disease. Post-CTCA diagnosis of angina pectoris due to coronary heart disease was classified as yes, probable, unlikely or no. Results Patients had a mean body mass index of 29 (28, 30) kg/m2, heart rate of 58 (57, 60)/min and 62% were men. Intraobserver and interobserver agreements for the presence or absence of coronary artery disease were excellent (95% agreement, κ 0.884 (0.817 to 0.951) and good (91%, 0.791 (0.703 to 0.879)). Intraobserver and interobserver agreement for the presence or absence of angina pectoris due to coronary heart disease were excellent (93%, 0.842 (0.918 to 0.755) and good (86%, 0.701 (0.799 to 0.603)), respectively. Observer variability of calcium score was excellent for calcium scores below 1000. More segments were categorised as uninterpretable with 64-multidetector compared to 320-multidetector CTCA (10.1% vs 2.6%, p<0.001) but there was no difference in observer variability. Conclusions Multicentre multidetector CTCA has excellent agreement in patients under investigation for suspected angina due to coronary heart disease. Trial registration number NCT01149590.

Does intermittent pneumatic compression reduce the risk of post stroke deep vein thrombosis?: The CLOTS 3 trial: study protocol for a randomized controlled trial

BackgroundApproximately 80,000 patients each year are admitted to UK hospitals with an acute stroke and are immobile. At least 10% will develop a proximal Deep Vein Thrombosis in the first month and 1.5% a pulmonary embolus. Although hydration, antiplatelet treatment and early mobilisation may reduce the risk of deep vein thrombosis, there are currently no preventive strategies which have been clearly shown to be both effective and safe. Anticoagulation increases the risks of bleeding and compression stockings are ineffective. Systematic reviews of small randomized trials of intermittent pneumatic compression have shown that this reduces the risk of deep vein thrombosis in patients undergoing surgery, but that there are few data concerning its use after stroke. The CLOTS trial 3 aims to determine whether, compared with best medical care, best medical care plus intermittent pneumatic compression in immobile stroke patients reduces the risk of proximal deep vein thrombosis.Methods/DesignCLOTS Trial 3 is a parallel group multicentre trial; with centralized randomisation (minimisation) to ensure allocation concealment. Over 80 centres in the UK will recruit 2800 immobile stroke patients within the first 3 days of their hospital admission. Patients will be allocated to best medical care or best medical care plus intermittent pneumatic compression. Ultrasonographers will perform a Compression Duplex Ultrasound Scan to detect deep vein thrombosis in each treatment group at about 7-10 days and 25-30 days. The primary outcome cluster includes symptomatic or asymptomatic deep vein thrombosis in the popliteal or femoral veins detected on either scan. Patients are then followed up by postal or telephone questionnaire at 6 months from randomisation to detect later symptomatic deep vein thrombosis and pulmonary emboli and to establish their functional outcome (Oxford handicap scale) and quality of life (EQ5D-3 L). The ultrasonographers performing the scans are blinded to treatment allocation, whereas the patients and caregivers are not. The trial has 90% power to detect a 4% absolute difference in risk of the primary outcome and includes a health economic analysis.DiscussionThe trial started recruitment in Dec 2008 and will complete recruitment during 2012. It will report results in 2013.Trial registration numberISRCTN: ISRCTN93529999