International Journal of Current Medical And Applied Sciences, 2017, August, 15(3),157-161.

IJCMAAS,E-ISSN:2321-9335,P-ISSN:2321-9327. Page | 157

Imaging of Associations with Tetralogy of Fallot by 256 Slice Multidetector CT

Jawahar Rathod1, Prajwalit Gaur1 & Kiran Chavan2

1Associate Professor, 2Resident, Department of Radiology, Government Medical College & Hospital, Nagpur, {MS} India.

--------------------------------------------------------------------------------------------------------------------------------------- Abstract:

Purpose: To demonstrate the superior role of 256 Slice Multidetector computed tomography (MDCT) in delineation of the common associations with Tetralogy of Fallots mainly extracardiac vascular abnormalities including the pulmonary arterial anomalies, major aortopulmonary collateral arteries (MAPCAs), patent ductus arteriosus (PDA), and also the detection of uncommon findings in Fallot Tetralogy cases for proper pre-surgical evaluation. Material and Methods: A retrospective study of all 256 multidetector CT images studied to evaluate suspected cases of Tetralogy of Fallot Referred from Medicine & Pediatrics Department to Department of Radiology, Government Medical College& Hospital, Nagpur [MS], India between December 2014 to November 2016. A total of 21 cases were included in this study. Results: 256 slice MDCT imaging findings in the 21 cases with Tetralogy of Fallot evaluated in detail in respect to the common and uncommon associations with TOF like pulmonary artery anamolies, MAPCAs, PDA, Atrial septal defects (ASDs), Right sided aortic arch and SVC related i.e. double SVC. Conclusion : 256 Slice MDCT examinations genuinely play superior role for optimum and tailored pre-surgical planning where Echocardiography data was insufficient for pre-operative surgical planning. Keywords: Tetralogy of fallot, 256 MDCT, Associations with TOF.

Introduction:The Tetralogy of Fallot was first described by Louis Arthur Etienne Fallot in 1888 as ‘‘La Maladie Bleue’’ [1]. It consists of following components namely ventricular septal defect, biventricular connection of the aortic root, overriding of aorta, right ventricular outflow tract obstruction and right ventricular hypertrophy. Common associations of Tetralogy of Fallot are Pulmonary artery atresia, Pulmonary artery stenosis, Right-sided aortic arch, Atrial septal defect (ASD) (so called Pentalogy of Fallot) and Coronary artery abnormalities. Other less common associations include persistent left superior vena cava (SVC) and aberrant right subclavian artery. The pulmonary valve is often abnormal, with a variably hypoplastic annulus and thickened, fused, and doming leaflets producing valvular stenosis [2]. The main or branch pulmonary arteries may be hypoplastic or atretic

and may be affected by discrete peripheral stenosis. A substantial percentage of patients with TOF have atresia instead of stenosis of the pulmonary valve, with no physiologic ante grade pulmonary blood flow. Pulmonary blood flow may come from PDA or aortopulmonary collateral arteries. The VSD is typically large, unrestrictive, and subaortic, involving the membranous septum. The extent of the aortic override is variable, and the overriding aortic root is typically enlarged. MDCT can show the size of the pulmonary arteries and are also useful for showing the origin and size of aortico-pulmonary collateral vessels and PDA. Surgical correction is done by closure of the VSD and relief of right ventricular outflow obstruction when patients are young.

Address for correspondence:

Dr. Kiran Chavan, Resident,

Department of Radiology, Government Medical College & Hospital, Nagpur [MS], India Email: dckrc01@gmail.com

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How to cite this article: Jawahar Rathod, Prajwalit Gaur & Kiran Chavan : Imaging of Associations with Tetralogy of Fallot by 256 Slice Multidetector CT. International Journal of current Medical and Applied sciences; 2017, 15(3),157-161.

Jawahar Rathod, Prajwalit Gaur & Kiran Chavan

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So for precise preoperative planning, the surgeon needs the best perception of the malformation [3, 4]. The development of 256 -section MDCT, with its high scanning speed, superior spatial resolution, and improved capabilities for concurrent assessment of cardiovascular structures and lung parenchyma, has proved its superior role for evaluation of patients even in small infants. The purpose of this study is to demonstrate the superior role of 256 MSCT in delineation of the various common associations in TOF namely extracardiac vascular abnormalities including the pulmonary arterial tree, MAPCAs & patent ductus arteriosus (PDA) and also the detection of uncommon association for proper pre-surgical evaluation.

Materials and Methods: The study was done at the Department of Radio-diagnosis, GMCH, Nagpur from cases between the duration of December 2014 – November 2016 . Institution: - Department of Radio-diagnosis, GMCH, Nagpur. Duration of Study: 2 Years (December 2014 – November2016). Study Design: Retrospective Study We retrospectively reviewed all multidetector CT images acquired to evaluate suspected cases of Tetralogy of Fallot sent by their respective referring physicians between (December 2014 –November 2016) within our Dept. of Radiology, Government Medical College & Hospital, Nagpur [MS], India. This yielded a total of 24 cases, who were examined by MDCT. 3 patients came for post-op follow up after surgical correction by BT shunt. So, not included in results. The findings in these 21 patients of TOF had been evaluated in detail. The MDCT results were correlated with the results of echocardiography (n =21 cases). All MDCT scans were obtained with 256-Slice MDCT scanner (PHILIPS BRILLIANCE iCT). Inclusion Criteria: All patients presenting to the hospital clinically suspected with TOF referred for Cardiac MDCT were included, regardless of whether they were referred to or born in our hospital. Exclusion Criteria: Patients with renal insufficiency, hemodynamic instability. Patient Preparation:

• NBM for 4-6 hours. • Recent Sr. creatinine, ECG and 2D

echocardiography reports. • Patient position—Supine lying with feet first

& Hands to be raised above head and ECG leads are fixed.

• In CT imaging of congenital heart disease, goal is to simultaneously achieve adequate vascular enhancement and minimal perivenous artifacts.

• A protocol employing a saline chaser with using a single- or dual-head power injector allows us to reduce the amount of contrast agent and the perivenous artifacts for thoracic CT.

256 Slice Imaging Protocol: • All patients were scanned with a 256-slice

CT scanner (Philips Brilliance i 256 slice CT) equipped with a new feature in multislice CT technology.

• 2 slices per detector row were acquired: improved spatial resolution.

• The Scanning parameters were kept as :

Scanning parameters Detector collimation 128–0.625 mm Section collimation 128–0.6 mm

Gantry rotation time 330 ms Pitch 0.18

Tube potential 120/100/80 kVp Tube current (mA) Automatic

modulation Contrast volume

(mL/kg) 2ml/kg

Data acquisition was performed in a cranio-caudal direction from the level of the thoracic inlet down to the diaphragm. Modifications in FOV done depending on Clinical indication, FOV increased for assessment of pulmonary vasculature and MAPCA in TOF etc. Retrospective ECG gating was done by applying ECG leads. Suitable anaesthesia was given in children and uncooperative patients. Contrast enhancement was achieved by non-ionic contrastagent (Ultravist 370 – iopromide). Amount of contrast calculated according to the patient weight, with a maximum dose of 2 ml/kg injected at 2 ml/s, pressure 100 through an 22-gauge catheter into peripheral vein. Scanning initiation was triggered by identification of a density of 150 HU in the ascending aorta most commonly and depending on the clinical indication in specific cardiac chamber or great vessel. Images were reconstructed at the optimum phase of the R–R interval with the least motion artifacts. Image Analysis: Review of the axial images was the most important step in image analysis. Multiplanar reformations, Curved planar reformats, MIP images and Volume rendered images were assessed in all patients. Measurements were taken from pulmonary arteries, ascending and descending thoracic aorta and aortic arch. Multiplanar reformation was individually adjusted to the long axis of the structure of interest to obtain accurate measurements. Volume rendering was the most lengthy post processing technique, yet it was helpful for the 3D visualization of complex anatomy.

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Results and Observations: In present study, 21 cases were enrolled, out of that 09(42.9%) cases were male and 12(57.1%) were female. Present study was conducted in age group of one day to 12 years of cases, out of that maximum i.e 12(57.1%) were in the age group of 6 months to 2 years. Table: 1 Anomalies Associated with Tetralogy of Fallots (N=21 Patients)

Associated Anomaly No. of Patients Percentage Right sided aortic arch 8 38.0%

Pulmonary Artery Anomalies 19 90.4% PDA 5 23.8%

MAPCAs 10 47.6% ASD 5 23.8%

Coronary artery Anomalies 4 19.0% Persistent left sided superior vena cava 7 33.4%

Pulmonary Artery Anomalies seen in 19 (90.4%) was most found associated anomaly with TOF followed by MAPCA'S 10(47.6%) cases & Right sided aortic arch 08(38.0%) of cases. Anamolies Associated with Tetralogy of Fallot: There were 21 patients with TOF. Pulmonary artery Anomalies is most found associated anomaly with TOF seen in 19 (90.4%) cases followed by MAPCA'S (Fig 1-3) seen in 10 (47.6%) cases & Right sided aortic arch in 8 (38%) cases. DSVC seen in 33% of cases. ASD was associated with 5 cases of TOF which are termed as Pentalogy of Fallot's. PDA seen in 5 (19%) cases with exact delineation of their configuration & diameter. Coronary artery anomalies were seen in 5 (23%) cases which were myocardial bridging, ALCAPA etc. 19 cases had complex Pulmonary artery anatomy (Fig 1-5) with various following combinations (Table: 2). Table 2: Pulmonary Artery Anomalies

Pulmonary Artery Anomalies No. of Patients Percentage

MPA Atresia 2 10.5% MPA & Both Branches Atresia 4 21.0%

MPA Stenosis 4 21.0% MPA & Both Branches Stenosis 4 21.0%

MPA & LPA Stenosis 2 10.5% LPA Stenosis only 2 10.5% RPA Stenosis only 1 5.3%

MAPCA’s are seen in 10 cases of TOF. 4 cases with main pulmonary artery atresia were associated with MAPCA & 6 cases of Pulmonary artery stenosis were associated with MAPCAs.

Figure :1 Figure: 2 Figure 1 & Figure 2: VRT & MIP Image showing Atretic MPA & LPA With MAPCA

Figure :3 Figure :4 Figure :5 Figure 3: VRT Image Showing Atretic MPA Only With Normal LPA & RPA & Tiny Mapcas from Desc Aorta & Arch of Aorta. Figure 4 & 5: VRT & MIP Image respectively showing Narrow MPA & Narrow LPA with Normal sized RPA.

Jawahar Rathod, Prajwalit Gaur & Kiran Chavan

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Discussion: For diagnosing Congenital heart disease, Echocardiography is still the preferred modality for imaging intracardiac anatomy and haemodynamics. However, it has some limitations, namely the small field of view, the variable acoustic window, its inability to penetrate air and bone and the associated difficulty in assessing the extra-cardiac vascular structures [5]. Advantages of 256-SLICE MDCT: [6] 256 Slice Multidetector CT provides superior diagnostic accuracy in assessment of patients with Tetralogy of Fallot regarding the central and peripheral pulmonary arteries, aorto pulmonary collateral vessels as well as in delineation of the abnormal venous anatomy. The 256-slice CT scanner takes only one second to scan the entire heart providing more information with each rotation - compared to four rotations with a 64-slice CT scanner, or 16 rotations with a 16-slice CT scanner. These older generation CT scanners take much longer to image the heart and require administration of medications to slow the heart rate to an accurate picture. Another added benefit to the 256-slice scanner is that patients do not need to hold their breath during the scan. Many patients especially children are struggle to maintain an adequate breath hold, which results in un-interpretable images and possible need to repeat the scan. The 256-slice CT scanner can give cardiologists a picture of the human heart with 60 percent less radiation exposure than older CT scan technology on average and in some patients. In the current study, all the intracardiac and extracardiac vascular associations were clearly diagnosed, even those that were missed or were unvisualised during the 2D-ECHO examination. The complex pulmonary artery anatomy and pulmonary artery anomalies i.e. Pulmonary artery atresia to stenosis in patients with Tetralogy of Fallot's is precisely identified by 256 MSCT, along with the major aorto-pulmonary collateral vessels without missing a single abnormality. In the Present study, MDCT detected 4(20%) cases of Pulmonary artery atresia involving the main trunk as well as the major branches, 02(10%) cases with main pulmonary artery trunk alone. Stenosis of main pulmonary artery seen in 4(20%) cases & stenosis main pulmonary artery along with its both branches seen in another 4 cases of TOF . So various combinations of atresia & stenosis involving main pulmonary artery & it's right /left branch pulmonary artery precisely evaluated by 256 cardiac MDCT as mentioned in observations. MAPCA'S (Major Aorto-Pulmonary Collaterals) found in 10 cases (57.6%), responsible for maintenance for pulmonary circulation were evaluated precisely by MDCT.

5(23%) cases were diagnosed with PDA in the current study which is responsible for supply to pulmonary arteries and 256 MDCT could clearly demonstrate their patency, their extensions, their length and diameter as well as their exact location. 8 patients of Tetralogy of Fallot's have an associated Right aortic arch (38%), which causes no major haemodynamic consequence. Persistent left sided superior vena cava i.e. Double SVC found in 7(33.4%) cases. Normally, the right anterior cardinal and common cardinal veins form the SVC and the left anterior cardinal vein regresses. A double SVC is the result of persistence of the left anterior cardinal vein. If, in addition, the normally persistent right cardinal vein regresses, then there is only a left SVC [7]. Atrial septal defect was found in 5 patients & hence classified as Pentalogy of Fallot's. Associated Coronary artery anomalies found in 5 (23%) cases. Out of which 3 cases of myocardial bridging, 1 case of ALCAPA & 1 case of Malignant RCA were detected precisely , all of these anomalies needs to be kept in mind or addressed prior to surgical intervention for TOF. In situs inversus, the morphologic right atrium lies to the left of the morphologic left atrium [8]. All the cases of this study had situs solitus, except for one case which had ventriculo arterial discordance i.e. double outlet right ventricle. Three patients of TOF are postoperatively sent for follow up which are not included statistical data. However, 256 MDCT precisely evaluated status of modified BT (Blalock-Tossing) Shunt. In addition Pulmonary arterial hypertension leading to changes of pulmonary edema, honey combing of lung & other vascular variation like Bovine arch were all commented upon by 256 MDCT. Above observations regarding associations with TOF were in concordance with study done by Rania H. Zakaria et al [9] study in which they retrospectively studied 23 patients of TOF on MDCT Imaging for common & uncommon associations which found Pulmonary artery anomalies as a most found association with TOF & PDA found in 30% of patients. Detailed evaluation of Associated Coronary artery anomalies, Pulmonary artery stenosis & MAPCA in patients of TOF for preoperative decision. Our study evaluated this in detail which found in concordance with study done by Wu lb et al. [10] & Vastel et al. [11].

Conclusion: 256 Slice MDCT examinations genuinely play superior role for optimum and tailored pre-surgical planning where Echocardiography data was insufficient for pre-operative surgical planning. In a suspected cases of Tetralogy of Fallot's, besides diagnosing the condition, it precisely identifies Associated pulmonary artery anomalies, MAPCAs & other vital associations which plays crucial role in

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preoperative planning & gives precise roadmap to operating surgeon. 256 MDCT have enhanced non-invasive imaging of children with TOF by (1) improving temporal and spatial resolution; (2) decreasing scan times; (3) reducing need for sedation; therefore radiation dose too; and (4) generating high-quality, visually accessible, and anatomically meaningful two-dimensional and three-dimensional images of cardiovascular structures (MPR, MIPS and Volume Rendered images).

Acknowledgment: It is a privilege to express our thanks to all those who provided invaluable help and encouragement during the period of the study and without whom this would not have been possible. We deeply indebted to Dr. Aarti Anand, Professor & Head of department of Radio-Diagnosis, Government Medical College & Hospital, Nagpur, for her affectionate guidance, meticulous attention and invaluable co-operation during the study, which helped to proceed in the right direction. We are also grateful to all the staff of our department especially for their unconditional and timely help.

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Conflict of interest: None declared Source of funding: None declared