Low-dose ultra-high-pitch computed tomography coronary angiography: identifying the optimum combination of iteration strength and radiation dose reduction strategies to achieve true submillisievert scans

PURPOSE: To identify the optimum strength of advanced modeled iterative reconstruction (ADMIRE) to achieve the best subjective and objective image quality when combining three-dose reduction strategies, ultra-high-pitch computed tomography coronary angiography (FLASH CTCA; with single-dose ivabradine to lower heart rate), low tube voltage, and ADMIRE. METHODS: Sixty consecutive patients underwent FLASH CTCA at 100 kVp in this single-center prospective study. Single-dose ivabradine was administered to patients whose heart rate was above 75 bpm. Images were reconstructed using the three highest strengths of ADMIRE (A3, A4, and A5). Objective and subjective image quality (using a Likert scale) were evaluated in the three datasets. RESULTS: The signal strength remained unchanged but mean noise significantly reduced across the increasing strengths of ADMIRE [signal: 513.78 ± 101.7 Hounsfield units (HU) at A3, 515.6 ± 100.5 HU at A4, and 519.7 ± 107.9 HU at A5; noise: 23.4 ± 4.5 HU at A3, 20.2 ± 3.6 HU at A4, and 17.2 ± 3.3 HU at A5]. Signal-to-noise and contrast-to-noise ratios were the highest at A5, and A5 offered significantly higher Likert scores in image noise, vessel sharpness, and overall image quality than A3 or A4. Additionally, A5 did not interfere with image interpretation in any patient. CONCLUSION: Using all three dose reduction strategies during FLASH CTCA along with single-dose ivabradine administration ensures minimal radiation exposure in daily practice. In this study, A5 datasets had the best overall subjective and objective image quality despite their "plastic appearance". In the future, enhanced dose reduction can be obtained by further lowering tube voltages.

Role of Cardiac MRI Including LGE, T1 and T2 Mapping in the Assessment of Cardiac Involvement in Patients of Nonspecific Aorto-arteritis: A Prospective Study.

Objective Nonspecific aorto-arteritis (NSAA) may involve the myocardium in the form of edema and fibrosis. We conducted this study to investigate role of cardiac MRI including late gadolinium enhancement (LGE), T1 and T2 mapping in the assessment of cardiac involvement in NSAA. Methods and Materials Over the period between 2016 and 2019, 36 patients with NSAA presenting with uncontrolled hypertension, left ventricular dysfunction, congestive cardiac failure, or tachyarrhythmia were included in the study. We also had 16 voluntary control patients for providing normal T1 and T2 mapping values. Results The average age of patients was 27.1 years and the majority were females. MRI is more sensitive than echocardiography in the detection of LV dysfunction and RWMA. Out of 36 patients, 10 (27.8%) had LGE. The most common pattern of midmyocardial enhancement was present in 5 out of 10 patients. Five (13.8%) patients show mid-myocardial enhancement, followed by epicardial enhancement, which was seen in four (11.11%) patients. The values of post-gad T1 mapping values were significantly lower than pre-gad T1 mapping values. At a cut-off global native T1 mapping value of 1019 milliseconds had the sensitivity of 83.3% and specificity of 81.2% in detecting an abnormal T1 map. No significant association of MRI contrast enhancement with elevated ESR and CRP levels. There was no significant relation of myocardial T2 mapping values between NSAA and control groups. Conclusion Quantitative tissue characterization in the myocardium with native T1 mapping values help in the detection of cardiac involvement in patients with NSAA. T1 mapping may provide incremental value in the assessment of myocardial involvement in NSAA in addition to LGE imaging.

Detection of cardiac allograft vasculopathy on dual source computed tomography in heart transplant recipients: comparison with invasive coronary angiography.

OBJECTIVE: We aimed to evaluate the diagnostic accuracy (DA) of dual-source CT coronary angiography (DSCTCA) against invasive coronary angiography (ICA) in assessing stenotic cardiac allograft vasculopathy (CAV) in heart transplant (HTX) recipients. METHODS: Consecutive HTX recipients(n = 38) on annual surveillance, underwent DSCTCA prior to ICA on a 192-detector 384-slice DSCT scanner. Cases were classified as no CAV (no stenosis), any CAV (any degree of stenosis) or significant CAV (>50% stenosis). RESULTS: Mean age was 33.66 ± 11.45 years (M:F = 27:11, median time from HTX-23.5 months). Prevalence of any CAV on DSCTCA and ICA was 44.7%(n = 17) and 39.5%(n = 15), respectively and that of significant CAV was 21.1%(n = 8) and 15.8%(n = 6), respectively. 557 (96.7%) segments were interpretable on DSCTCA. Mean radiation dose was 4.24 ± 2.15 mSv. At patient-level, the sensitivity, specificity, positive-predictive value, negative-predictive value (NPV), and DA of DSCTCA for detection of any CAV and significant CAV were 100%, 91.3%, 88.2%, 100%, 94.73% and 100%, 94%, 75%, 100%, 95% respectively. The same on segment-based analysis were 96%, 97.6%, 80%, 99.6%, 97.5% and 100%, 99.6%,86.7%,100%, 99.6%, respectively. There was excellent agreement between the two modalities for detection of any CAV and significant CAV [κ = 0.892 and 0.826 (patient-level), 0.859 and 0.927 (segment-level)]. CAC score correlated significantly with the presence of any CAV on both modalities. A diagnosis of rejection on biopsy did not correlate with any/significant CAV on DSCTCA or ICA. CONCLUSION: High sensitivity and NPV of DSCTCA in the evaluation of stenotic CAV suggests that it can be an accurate and non-invasive alternative to ICA for routine surveillance of HTX recipients. ADVANCES IN KNOWLEDGE: DSCTCA detects the stenotic CAV non-invasively in transplant recipients with high sensitivity, specificity and NPV when compared with catheter coronary angiography, at lower radiation doses. There is excellent agreement between CT angiography and catheter coronary angiography for detection of any CAV and significant CAV. A diagnosis of rejection on biopsy does not correlate with any/significant CAV on CT angiography or catheter angiography.

Clarifying the anatomy of the superior sinus venosus defect.

OBJECTIVES: We sought to clarify the variations in the anatomy of the superior cavoatrial junction and anomalously connected pulmonary veins in patients with superior sinus venosus defects using computed tomographic (CT) angiography. METHODS: CT angiograms of 96 consecutive patients known to have superior sinus venosus defects were analysed. RESULTS: The median age of the patients was 34.5 years. In seven (7%) patients, the defect showed significant caudal extension, having a supero-inferior dimension greater than 25 mm. All patients had anomalous connection of the right superior pulmonary vein. The right middle and right inferior pulmonary vein were also connected anomalously in 88 (92%) and 17 (18%) patients, respectively. Anomalous connection of the right inferior pulmonary vein was more common in those with significant caudal extension of the defect (57% vs 15%, p=0.005). Among anomalously connected pulmonary veins, the right superior, middle, and inferior pulmonary veins were committed to the left atrium in 6, 17, and 11 patients, respectively. The superior caval vein over-rode the interatrial septum in 67 (70%) patients, with greater than 50% over-ride in 3 patients. CONCLUSION: Anomalous connection of the right-sided pulmonary veins is universal, but is not limited to the right upper lobe. Not all individuals have over-riding of superior caval vein. In a minority of patients, the defect has significant caudal extension, and anomalously connected pulmonary veins are committed to the left atrium. These findings have significant clinical and therapeutic implications.

Comparison of 68Ga-DOTANOC PET/CT with cardiac MRI in patients with clinical suspicion of cardiac sarcoidosis.

BACKGROUND: 68Ga-DOTA-NaI-octreotide (DOTANOC) is a promising new alternative to 18F-fluorodeoxyglucose (FDG) for imaging inflammation in cardiac sarcoidosis. The aim of the study was to compare 68Ga-DOTANOC positron emission tomography/computed tomography (PET/CT) with cardiac magnetic resonance imaging (CMR) in patients with clinical suspicion of cardiac sarcoidosis. METHODS AND RESULTS: Patients with extracardiac sarcoidosis and clinical suspicion of cardiac involvement underwent 68Ga-DOTANOC cardiac PET/CT, myocardial perfusion single photon emission computed tomography (MPS) and CMR (T2-weighted and delayed gadolinium-enhanced T1-weighted images). The patients were screened using revised criteria of Japanese circulation society. Presence of perfusion defects on MPS, abnormal myocardial uptake on 68Ga-DOTANOC PET/CT and characteristic pattern of late gadolinium enhancement (LGE) with or without T2 hyperintensity on CMR was considered positive. RESULTS: Seventeen patients (13 male and 4 female) were included in the study. Out of the 17 patients, both CMR and PET were positive in 11 and both were negative in 2. In the remaining 4 patients, CMR was positive but PET was normal. Thus, PET and CMR were concordant in 13 (76.5%) patients and discordant in 4 (23.5%). Intermodality agreement was fair (Cohen's kappa = 0.39). CONCLUSION: LGE on CMR is superior to 68Ga-DOTANOC PET/CT for detecting cardiac involvement in sarcoidosis and there is fair concordance between the two. However, since LGE does not specifically differentiate between inflammation and fibrosis, 68Ga-DOTANOC PET/CT may be better than CMR in identifying patients with active inflammation, since it directly targets inflammatory cells and can have a complementary role to CMR.

Comparison Between Time-Resolved Magnetic Resonance Angiography and Diagnostic Digital Subtraction Angiography in the Vascular Assessment of Nonspecific Aorto-Arteritis Patients: A Prospective Study.

PURPOSE: Nonspecific aortoarteritis (NSAA) is a chronic inflammatory vasculitis involving aorta and its branches. We conducted a study prospectively to compare time resolved magnetic resonance angiography (MRA) with diagnostic digital subtraction angiography (DSA) for the vascular assessment in the patients of NSAA. MATERIALS AND METHODS: Seventeen patients of NSAA were recruited in the study over the period of 3 years. Contrast enhanced MRA using Time-resolved angiography With Interleaved Stochastic Trajectories (TWIST) sequence and diagnostic DSA were performed in these 17 patients. RESULTS: The majority of the patients were young (median age was 25 years, range 8 to 46 years) and 11 patients were females. Erythrocyte sedimentation rate (ESR) was elevated in 9 patients and C-reactive protein (CRP) was elevated in 6 patients. Most commonly involved vessels in our patients were right renal artery (14 patients), abdominal aorta (12 patients) and left renal artery (11 patients). Left and right subclavian arteres were involved in 10 and 6 patients respectively. The sensitivity and specificity of time-resolved MRA using TWIST sequence is 100% as compared to DSA in the assessment of major vessels such as aorta, arch vessels, celiac artery and superior mesenteric artery. However, the sensitivity and specificity of time resolved MRA in the evaluation of renal arteries and vertebral arteries were 100%, 71.4% and 85.7%, 33.3% respectively. No significant association of MRI contrast enhancement with erythrocyte sedimentation rate (p = 1.00) and C-reactive protein (p = 0.600). CONCLUSION: Time resolved MRA images obtained using TWIST sequence were as qualitative as DSA images and can noninvasively evaluate the vascular involvement in NSAA patients.

Role of CMR feature-tracking derived left ventricular strain in predicting myocardial iron overload and assessing myocardial contractile dysfunction in patients with thalassemia major.

OBJECTIVE: Myocardial iron overload (MIO) in thalassemia major (TM) may cause subclinical left ventricular (LV) dysfunction which manifests with abnormal strain parameters before a decrease in ejection fraction (EF). Early detection of MIO using cardiovascular magnetic resonance (CMR)-T2* is vital. Our aim was to assess if CMR feature-tracking (FT) strain correlates with T2*, and whether it can identify early contractile dysfunction in patients with MIO but normal EF. METHODS: One hundred and four consecutive TM patients with LVEF > 55% on echocardiography were prospectively enrolled. Those fulfilling the inclusion criteria underwent CMR, with T2* being the gold standard for detecting MIO. Group 1 included patients without significant MIO (T2* > 20 ms) and group 2 with significant MIO (T2* < 20 ms). RESULTS: Eighty-six patients (mean age, 17.32 years, 59 males) underwent CMR. There were 68 (79.1%) patients in group 1 and 18 (20.9%) in group 2. Fourteen patients (16.3%) had mild-moderate MIO, and four (4.6%) had severe MIO. Patients in group 2 had significantly lower global radial strain (GRS). Global longitudinal strain (GLS) and global circumferential strain (GCS) did not correlate with T2*. T1 mapping values were significantly lower in patients with T2* < 10 ms than those with T2* of 10-20 ms; however, FT-strain values were not significantly different between these two groups. CONCLUSION: CMR-derived GRS, but not GLS and GCS, correlated with CMR T2*. GRS is significantly decreased in TM patients with MIO and normal EF when compared with those without. FT-strain may be a useful adjunct to CMR T2* and maybe an early marker of myocardial dysfunction in TM. KEY POINTS: • A global radial strain of < 29.3 derived from cardiac MRI could predict significant myocardial iron overload in patients with thalassemia, with a sensitivity of 76.5% and specificity of 66.7%. • Patients with any myocardial iron overload have significantly lower GRS, compared to those without, suggesting the ability of CMR strain to identify subtle myocardial contractile disturbances. • T1 and T2 mapping values are significantly lower in those with severe myocardial iron than those with mild-moderate iron, suggesting a potential role of T1 and T2 mapping in grading myocardial iron.

Randomized, Double-Blind, Placebo-Controlled Trial to Evaluate Safety and Therapeutic Efficacy of Angiogenesis Induced by Intraarterial Autologous Bone Marrow-Derived Stem Cells in Patients with Severe Peripheral Arterial Disease.

PURPOSE: To evaluate safety and efficacy of angiogenesis induced by intraarterial autologous bone marrow-derived stem cell (BMSC) injection in patients with severe peripheral arterial disease (PAD). MATERIALS AND METHODS: Eighty-one patients with severe PAD (77 men), including 56 with critical limb ischemia (CLI) and 25 with severe claudication, were randomized to receive sham injection (group A) or intraarterial BMSC injection at the site of occlusion (group B). Primary endpoints included improvement in ankle-brachial index (ABI) of > 0.1 and transcutaneous pressure of oxygen (TcPO2) of > 15% at mid- and lower foot at 6 mo. Secondary endpoints included relief from rest pain, > 30% reduction in ulcer size, and reduction in major amputation in patients with CLI and > 50% improvement in pain-free walking distance in patients with severe claudication. RESULTS: Technical success was achieved in all patients, without complications. At 6 mo, group B showed more improvements in ABI of > 0.1 (35 of 41 [85.37%] vs 13 of 40 [32.50%]; P < .0001) and TcPO2 of > 15% at the midfoot (35 of 41 [85.37%] vs 17 of 40 [42.50%]; P = .0001] and lower foot (37 of 41 [90.24%] vs 19 of 40 [47.50%]; P < .0001). No patients with CLI underwent major amputation in group B, compared with 4 in group A (P = .0390). No significant difference was observed in relief from rest pain or > 30% reduction in ulcer size among patients with CLI or in > 50% improvement in pain-free walking distance among patients with severe claudication. CONCLUSIONS: Intraarterial delivery of autologous BMSCs is safe and effective in the management of severe PAD.

Impact of bariatric surgery on carotid intima-medial thickness and cardiovascular risk: results of a prospective study.

BACKGROUND: The impact of bariatric surgery on atherosclerosis is a relatively less studied subject. Obesity has been identified as an independent risk factor for cardiovascular disease (CVD). Carotid intima-media thickness (CIMT), a surrogate marker for atherosclerosis and risk of CVD, has been found to be associated with obesity. Recent literature has shown that there is significant reduction in CIMT following bariatric surgery. The aim of this study was to evaluate the impact of bariatric surgery on CIMT and risk of CVD in an Indian population. METHODS: This is a prospective study conducted in a tertiary referral centre in India. Patients undergoing bariatric surgery from December 2017 to September 2019 were included. CIMT measurements and American College of Cardiology/American Heart Association (ACC/AHA)-pooled cohort CVD risk scores were done before and at 6 months and 12 months after surgery. RESULTS: Fifty-four patients were enrolled, of which 70% were females. Mean age was 40.8 ± 10.7 years. Mean pre-operative weight and mean BMI were 115.2 ± 21.9 kg and 45.9 ± 6.5 kg/m2, respectively. Patients who completed 12-month follow-up were considered for analysis of outcomes. There was significant reduction in BMI to 33.1 ± 5.7 kg/m2 at 12 months after surgery (p < 0.0001). Mean CIMT reduced significantly from 0.58 ± 0.08 mm at baseline to 0.52 ± 0.10 mm at 12 months. Lipid profile, fasting blood sugar and HbA1C also improved, which resulted in reduction of lifetime and 10-year CVD risk from 42.3 to 26% and 4 to 1.5%, respectively, at 12 months after surgery. CONCLUSIONS: Bariatric surgery results in significant reduction in CIMT and CVD risk in patients with morbid obesity.

Systolic excursion of the leaflets of the truncal valve: An unusual mechanism for pulmonary stenosis in common arterial trunk.

BACKGROUND: Pulmonary stenosis in patients with common arterial trunk protects the pulmonary vasculature. In our recently published prospective study of common arterial trunk, some patients with sinusal origin of the pulmonary arterial segment had pulmonary stenosis induced by systolic excursion of a truncal valvar leaflet. We aimed to determine the detailed morphologic characteristics of this unusual finding. METHODS AND RESULTS: All 70 patients underwent echocardiography and computed tomographic angiography as per predefined study protocol. In selected cases, we also performed cardiac catheterization. Among 27 patients with aortic dominance, we found sinusal origin of the pulmonary arterial segment. In 5 of these patients, pulmonary stenosis was induced by systolic excursion of a truncal valvar leaflet. In all these patients, the truncal valve was trisinusate, albeit with asymmetric sinuses. The pulmonary arterial segment arose from the largest left sinus with its relatively large leaflet obstructing the pulmonary orifice during systole. In the remaining 22 patients, without pulmonary stenosis but with sinusal origin of pulmonary arterial segment, the truncal valve was quadrisinusate in 7, bisinusate in 2, and trisinusate in 13. None of the patients with quadrisinusate and bisinusate truncal valves had pulmonary stenosis. Among the 13 patients with trisinusate valves, the sinuses of the truncal valve were symmetrical in 6, while in 7, the pulmonary orifice originated from a smaller asymmetric sinus. CONCLUSION: Pulmonary stenosis, produced by a relatively large leaflet of an asymmetric truncal sinus, may prevent early development of pulmonary vascular disease. Timely recognition of this unusual mechanism of pulmonary stenosis is important for optimal management.

Circumflex retroesophageal left aortic arch with right ductus arteriosus: A rare complete vascular ring diagnosed on computed tomography angiography.

A circumflex retroesophageal left aortic arch with a right-sided ductus is an extremely rare cause of a complete vascular ring, which may result in severe tracheobronchial compression, leading to respiratory compromise, especially in children. We present a case of a 6-month-old female child with stridor and feeding difficulties since birth with interspersed self-resolving episodes of cyanosis and apnea, secondary to the presence of the above-mentioned vascular ring.

Feasibility and Accuracy of Aortic Valve Calcium Quantification on Computed Tomographic Angiography in Aortic Stenosis.

BACKGROUND: Traditionally, quantification of aortic valve calcium (AVC) has been performed with noncontrast computed tomography (NCCT) using the Agatston method. This study sought to derive and validate a systematic method enabling AVC quantification using computed tomographic angiography (CTA) in patients with aortic stenosis (AS). METHODS: The study included 134 consecutive patients with AS who underwent both NCCT and CTA and were subdivided into derivation (n = 71) and validation cohorts (n = 63). AVC on NCCT (AVCNCCT) was quantified using the Agatston method using the software developed for semiautomatic assessment of coronary calcium. On CTA, the mean contrast attenuation of the aorta in Hounsfield units (AortaHU) and SD was measured in the region of interest at the level of the sinotubular junction. RESULTS: Using an adjusted calcium detection threshold of AortaHU + 2 SD, we calculated AVC on CTA (AVCCTA) using the same software without modifying other variables. Correlation between AVCNCCT and AVCCTA in the derivation cohort was excellent (r = 0.9679; P < .001). We used a linear regression model to derive a formula for predicting AVCCTA that enabled conversion of AVCCTA to AVCDerived (AVCDerived = 1.821 × AVCCTA). Applying this formula in validation cohort, we calculated AVCDerived, which showed excellent agreement with AVCNCCT (intraclass correlation coefficient, 0.9648; 95% confidence interval, 0.9427-0.9782). Excellent correlation was also found between categorized AVCNCCT and AVCDerived scores (κ = 0.9044; 95% confidence interval, 0.7989-1.0000), with 95.24% (60 of 63) of scores falling within the same severity category. CONCLUSIONS: AVC quantification on CTA is feasible with high accuracy and reliability and shows excellent agreement with the standard AVCNCCT score. With the systematic approach using "dynamic thresholds" being largely independent of the scan acquisition protocol, AVCDerived can potentially replace AVCNCCT, eliminating the need for separate NCCT acquisition solely for AVC quantification.

Clarifying the anatomy of common arterial trunk: a clinical study of 70 patients.

AIMS: Anatomic variations in hearts with common arterial trunk are well-known, although there is no large study of living patients. Detailed knowledge of the origins of the pulmonary and coronary arteries is vital for surgical management. We sought to clarify the variations using computed tomography. METHODS AND RESULTS: We prospectively studied 70 consecutive patients using echocardiography and computed tomography. In 63 (90%) patients, there was aortic dominance, while 7 (10%) had dominance of the pulmonary component. In 27 (43%) patients with aortic dominance, part of the pulmonary segment arose from a truncal valvar sinus. A long confluent pulmonary channel was more common in patients with sinusal origin compared to those with non-sinusal origin of the pulmonary segment (19 vs. 0; P = 0.0005). Close proximity between the orifices of the coronary arteries and the pulmonary component was also more frequent with sinusal origin (21 vs. 6; P < 0.001) with 5 (19%) patients having pulmonary flow obstructed by a truncal valvar leaflet. CONCLUSION: Sinusal origin of the pulmonary component is common with aortic dominance, frequently in association with a long confluent pulmonary segment, which may be in close proximity to the origin of a coronary artery. One-fifth of patients with sinusal origin of pulmonary component have a truncal valvar leaflet obstructing the pulmonary orifice. These morpho-anatomic findings have important implications for management.

A curious case of impossible coronary sinus cannulation.

A 40-year-old male, diagnosed to have WPW syndrome and symptomatic with recurrent palpitations, was taken up for radiofrequency ablation. There was difficulty in coronary sinus cannulation. Coronary venogram revealed coronary sinus atresia with persistent left superior vena cava, and collateral venous pathways draining into the right atrium. This case is discussed for the rare coronary venous anomaly, its embryology and the difficulties in the management during electrophysiological studies.