This prospective study enrolled 30 cases; 16 (53.33%) males and 14 (46.67%) females, their ages ranged from 2 days to 18 years with a mean age of 20.223 ± 53.132 month. The most common age group was less than one month including 11 (36.67%) cases followed by age group from 4 months − < 12 months including 8 (26.67%) cases, 1 month − < 4 months including 7 (23.33%) cases and > 12 months including 4 (13.33%) cases.
According to the clinical presentation of the studied cases, 2 of them were asymptomatic and the other 28 cases were symptomatic presented with cyanosis (n = 15), dyspnea (n = 8), poor feeding (n = 7), tachypnea (n = 13), recurrent chest infection (n = 5) and failure to thrive (n = 2).
All the patients had Echocardiographic reports of suspected or diagnosed PDA and underwent MDCT angiography of the heart and great vessels to confirm the diagnosis. We compared cardiac MDCT findings with the data collected by cardiac catheterization and/or operation (gold standard).
Echocardiography detected PDA in 28 cases (93.3%) while MDCT angiography detected PDA in all studied 30 cases confirmed by cardiac catheterization and/or operation. MDCT angiography had sensitivity 100% and specificity 100% for PDA detection with the advantage of giving precise anatomical details and volume rendered images which are very helpful before surgery for accurate surgery planning.
Qualitative and quantitative assessment of PDA by cardiac MDCT
Twenty six cases had left sided PDA and 4 cases had right sided PDA. PDA originated from aortic isthmus in 15 cases (Fig. 1), inferior surface of aortic arch in 11 cases (Fig. 2, 3) and innominate artery in 4 cases (Fig. 4). The morphological type of PDA was evaluated according to Krichenko et al. classification , it was found that the most common type of PDA was type A (cone) detected in 14 (46.67%) cases followed by type C (tubular) detected in 7 (23.3%) cases (Fig. 2,3), type D (complex) detected in 3 (10%) cases, type E (elongated) detected in 4 (13.33%) cases (Fig. 1) and type B (window) detected in 2 (6.67%) cases (Fig. 5). According to tortuosity of PDA, it was straight (type I) in 15 cases, has one turn (type II) in 9 cases, and has multiple turns and tortuous (type III) in 6 cases.
The size of aortic end of PDA, pulmonary end of PDA, length of PDA, diameter of main pulmonary artery, diameter of aortic isthmus and descending aorta were calculated and compared according to the type of PDA as listed in Table 1.
The spearman correlation coefficient test demonstrated poor correlation between size of aortic end and MPA (P = 0.75), and between size of pulmonary end and diameter of MPA (P = 0.99). Fair correlation between length of PDA and MPA (P = 0.018). Also demonstrated poor correlation between size of aortic end and diameter of RPA (P = 0.57), between size of pulmonary end and diameter of RPA (P = 0.4), and between length of PDA and RPA (P = 0.12). The spearman correlation coefficient test demonstrated poor correlation between size of aortic end and diameter of LPA (P = 0.3), and between size of pulmonary end and diameter of LPA (P = 0.07). Fair correlation between length of PDA and LPA (P = 0.027), the above findings shown in Table 2 and Figs. 6, 7.
Associated cardiac andor extra cardiac anomalies with PDA
Among the studied 30 cases, PDA was isolated in 4 (13.3%) cases and associated with cardiac andor extra cardiac anomalies in 26 (86.6%) cases. Cardiac and extra cardiac anomalies associated with PDA detected by MDCT angiography included; ASD (n = 18), VSD (n = 16) (Figs. 2, 4, 5), pulmonary atresia (n = 7) (Fig. 4), transposition of great arteries (n = 5), teratology of Fallot (n = 4), aortic coarctation (n = 4), persistent truncus arteriosus (n = 3), tricuspid atresia (n = 3), anomalous of pulmonary venous return (n = 3), hypoplastic segment of aorta (n = 2), Ebstein’s anomaly (n = 1), bicuspid aortic arch (n = 1) and left hypoplastic heart syndrome (n = 1).
The associated anomalies were divided according to duct dependent lesions into duct dependent pulmonary circulation lesions (15 cases), duct dependent systemic circulation lesions (7 cases) and duct dependent lesions with combined mixing blood between systemic and pulmonary circulation (5 cases) with TGA. These associated anomalies are illustrated at Table 3.
Intra-cardiac anomalies associated with PDA
The intracardiac defects encountered within the study were classified into atrial and ventricular septal defects. The most common ventricular septal defect (VSD) was perimembranous VSD (8 cases, 26.6%). The most common atrial septal defect (ASD) was ostium secundum ASD (12 cases, 40%).
Cardiac MDCT missed the diagnosis of ASD in 1 case and VSD in 1 case, hard to interpret ASD in 1 case and VSD in 2 cases due to cardiac motion during the examination and accurately diagnosed other types of ASD and VSD. Chi square test revealed non statistically significant difference between Echo and MDCT angiography in detection of ASD (P = 0. 95) and VSD (P = 0.90) as listed in Table 4.
Extra-cardiac anomalies associated with PDA
Regarding aortic anomalies (Figs. 3, 5), Echocardiography missed aortic coarctation in 1 case, hypoplastic aortic segment in 3 cases, right sided aortic arch in 3 cases. However, MDCT angiography missed one case of aortic valve stenosis due to motion artifact that interfere with good interpretation of aortic valve anatomy as listed in Tables 5 and 6.
Different aortic arch branching patterns were detected by MDCT angiography; left sided aortic arch with normal branching pattern (n = 18), left sided arch with bovine branching pattern (n = 6), right sided aortic arch with mirror image branching pattern (n = 3), left sided with aberrant right subclavian artery (n = 1) (Fig. 1), and right sided aortic arch with aberrant left subclavian (n = 1).
Regarding coronary arteries anomalies, twenty-two cases had no coronary anomalies, 5 cases were hard to be interpretable due to motion artifact (high heart rate), 2 cases had single coronary artery and 1 case had ectatic left coronary artery with cameral fistula end at right ventricle (Fig. 1).
Regarding main pulmonary artery abnormalities (Figs. 1, 2), MDCT angiography detected pulmonary atresia in 4 (13.33%) cases, dilated MPA in 7 (23.33%) cases, MPA hypoplasia in 6 (20%) cases, subpulmonic stenosis in 1 (3.33%) case. While Echocardiography missed detection of two cases with pulmonary atresia, 1 case with sub pulmonic stenosis, 1 case of hypoplastic MPA and 1 case with dilated MPA. Chi square test revealed non statistically significant difference between both Echocardiography and cardiac MDCT in detection of main pulmonary artery anomalies. Regarding right pulmonary artery abnormalities, MDCT angiography reported RPA hypoplasia in 7 (23.3%) cases, ostial stenosis in 3 (10%) cases, dilated RPA in 7 (23.33%) cases. Echocardiography failed to diagnose 3 cases with dilated RPA, 3 cases with RPA hypoplasia and 3 cases with osteal stenosis. Regarding left pulmonary artery abnormalities, MDCT angiography revealed LPA hypoplasia in 8 (26.67%) cases, ostial stenosis in 4 (13.33%) cases, dilated LPA in 7 (23.3%) cases. Echocardiography failed to diagnose 5 cases with hypoplastic LPA, 3 cases with LPA osteal stenosis and 2 cases with dilated LPA.
Chi square test revealed statistically significant difference between Echocardiography and cardiac MDCT in detection of left pulmonary artery and right pulmonary artery anomalies (P = 0.05 for left pulmonary artery and P = 0.043 for right pulmonary artery) as listed in Table 7.
Cardiac MDCT missed diagnosis of one case with pulmonary stenosis and 2 cases with hypoplastic pulmonary artery branches due to cardiac motion which degrade the quality of the image as listed in Table 8.
Regarding pulmonary venous abnormalities, pulmonary veins were normal in 27 cases and venous anomalies were diagnosed in 3 cases; (TAPVR) total anomalous pulmonary venous return detected in 1 (3.33%) case, (PAPVR) partial anomalous pulmonary venous return detected in 2 (6.66%) cases. Echocardiography missed diagnosis of 2 cases with PAPVR. Chi square test revealed non statistically significant difference between both Echocardiography and MDCT in detection of pulmonary venous anomalies (P = 0.262).
Regarding systemic venous anomalies, cardiac MDCT detected four cases with double SVC and one case with left sided SVC. Echocardiography missed detection of double SVC in 3 out of 4 cases.
The MDCT scanner automatically estimated the absorbed radiation dose in the form of dose length product (DLP) (radiation dose for a predetermined scanned length). For transforming the DLP to effective radiation dose in milliSievert, it is agreed to multiply the DLP by conversion coefficient factor according to age. Thirty MSCT examinations were done, and the mean absorbed radiation dose was 91.79 ± 88.45 mGy per scan and the mean effective dose was 2.61 ± 1.38 mSv as illustrated in Table 9.
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