Radiol med (2014) 119:27–32 DOI 10.1007/s11547-013-0304-9
CHEST RADIOLOGY
Assessment of 64-row computed tomographic angiography for diagnosis and pretreatment planning in pulmonary sequestration Jian-Zhuang Ren • Kai Zhang • Guo-Hao Huang • Meng-Fan Zhang • Peng-Li Zhou • Xin-Wei Han • Xu-Hua Duan • Zhen Li
Received: 22 April 2012 / Accepted: 25 September 2012 / Published online: 15 November 2013 Ó Italian Society of Medical Radiology 2013
Abstract Purpose This study was done to evaluate the clinical implications and results of a prospective protocol using 64-row computed tomographic angiography (CTA) for diagnosis and pre-treatment planning in pulmonary sequestration (PS). Materials and methods Forty-five patients with suspected PS were referred for CTA examination. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of measures used to detect PS were determined by patient-based and aberrant systemic artery-based evaluations. The location, the size and the number of aberrant systemic arteries, and the feasibility of endovascular treatment were analysed. The capability of CTA to provide a working view and the accuracy of measurements in choosing a coil were also assessed. Results Digital subtraction angiography and/or surgery revealed PS in 38 patients, and 7 patients had no PS. The patient-based evaluation yielded an accuracy of 97.8 %, sensitivity of 97.4 %, specificity of 100 %, PPV of 100 % and NPV of 87.5 %, in the detection of PS. CTA clearly depicted the PS in all 38 patients, and the aberrant systemic artery was accurately demonstrated in 37 out of 38 patients where endovascular treatment was possible. Working views for endovascular treatment were found in all patients with PS, and the choice of coil was correct in 37 out of 38 patients using CTA. K. Zhang is the Co-first author. J.-Z. Ren (&) K. Zhang G.-H. Huang M.-F. Zhang P.-L. Zhou X.-W. Han X.-H. Duan Z. Li Department of Interventional Radiology, The First Affiliated Hospital, Zhengzhou University, No.1, East Jian She Road, Zhengzhou 450052, Henan, Republic of China e-mail: [email protected]
Conclusions 64-row CTA appears to be effective in terms of supporting accurate diagnosis and pre-treatment planning in PS. CTA is not only able to provide clear visualisation of aberrant systemic arteries but also provides detailed images of abnormal lung parenchyma and the airways. Keywords Pulmonary sequestration Angiography DSA Endovascular
Introduction Pulmonary sequestration (PS) is a rare congenital pulmonary disorder defined by an area of dysplastic and nonfunctioning pulmonary tissue which has an anomalous systemic blood supply [1]. Conventional digital subtraction angiography (DSA) is considered the gold standard for the diagnosis of PS [2]. In recent years, less invasive imaging techniques, particularly helical multislice computed tomographic angiography (CTA), have proved to be equally effective and safer alternatives to DSA [3–13]. CTA can provide the precise visualisation of the site, size and number of aberrant systemic arteries and their relationship to the aorta, which are fundamental factors that must be assessed before choosing between endovascular and neurosurgical treatments. Previous reports in the literature have assessed the sensitivity and specificity of CTA compared with DSA [3– 13]. However, these investigations have not analysed the clinical implications of a protocol that replaces DSA with CTA as the only diagnostic and pre-treatment planning tool for patients with PS. Therefore, the purpose of the current study was to evaluate the clinical implications and clinical results of a prospective protocol using 64-row CTA for the diagnosis and endovascular treatment of PS.
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Materials and methods Study design The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent before participation. From May 2008 to December 2011, patients with suspected PS detected by CTA underwent coil embolisation, surgical resection, or conservative treatment. DSA or surgery was performed after CTA to confirm the diagnosis of PS. A total of 45 consecutive patients were enrolled in the study. The patients included 28 males and 17 females with a mean age of 4.95 ± 9.00 years (range, 1 day to 45 years). The basic characteristics of the study patients are summarised in Table 1. 14 patients presented with recurrent fever, cough, and pulmonary infection, 3 with recurrent haemoptysis, and the remaining 28 patients were asymptomatic. Image acquisition CTA All CTA examinations were performed using a 64-row CT scanner (light speed VCT or Discovery CT750 HD, GE Healthcare) with a bolus tracking system. The smart
Table 1 Baseline characteristics of 45 patients with pulmonary sequestration (PS) Characteristic
All patients (n = 45)
PS (n = 38)
Non-PS (n = 7)
Age (years)
4.95 ± 9.00
3.78 ± 8.64
11.28 ± 8.90
Male sex-no. (%)
28 (62.2.2)
24 (63.2.5)
4 (57.1)
Location-no. (%) Left lower lobe
28 (62.2)
25 (65.8)
3 (42.9)
17 (37.8)
13 (34.2)
4 (57.1)
Intralobar
–
22 (4.2)
-
Extralobar
-
16 (4.2)
-
Right lower lobe Classification-no. (%)
Aberrant systemic artery-no. (%) Descending aorta
-
28
-
Abdominal aorta
-
10
-
Single artery
-
32
-
Multiple artery
-
6
-
Draining vein-no. (%) Pulmonary vein
-
26
-
Azygos vein
-
9
-
Hemiazygos vein
-
1
-
Portal vein
-
2
-
123
preset scan technique was used for enhanced CTA with the following parameters: 0.625 mm 9 64 slice, 120 kVp, 100–600 mA, 1.375:1 helical pitch, and with an acquisition time of 25.6 s. The standard dose for enhanced CTA was 0.7 ml/kg body weight in addition to 40 ml normal saline, and the contrast material was administered using a power injector at a rate of 4 ml/s through a 22-gauge needle in the antecubital vein. When the concentration of contrast medium in the ascending aorta reached 100 HU, the CT device automatically scanned from the apex of the lung to the upper abdomen. The acquired image data sets were then transferred to a workstation (GE AW4.3 or GE AW4.4, GE Medical), where 3D image reconstruction, comprising oblique, coronal and sagittal maximum-intensity projection (MIP), multiplanar reconstruction (MPR), and three-dimensional volume-rendered (VR) images of airway and thoracic vascular structures, was performed with a 732 9 732 matrix. Each patient was assessed for PS after a collateral artery originating from the aorta was identified in the scans. The site of origin, distribution, and course of PS were evaluated on the basis of MPR, MIP, and VR by adjusting the value of translucency or slab thickness. The diameter of PS was measured on MPR. The pulmonary arteries and veins of the affected lung were also evaluated. Each segmental bronchus of the involved lung was reconstructed using MPR and minimum intensity projections (MIP). The number and course of branches and the lung volume were also evaluated. DSA DSA was carried out by an interventional radiologist after CTA examinations. Conventional 2D-DSA was performed on a monoplanar unit (Axiom Artis VB22N, Siemens) with a 1,024 9 1,024 matrix and a 17 9 20 cm field of view. The access routes for angiography were the umbilical artery (neonates) and the femoral artery. After performing a complete haemodynamic evaluation, an initial aortogram was obtained to show the arterial map of the systemic feeders. The abnormal vessels were then selectively catheterised with a 4- or 5-Fr catheter. Angiography was carried out to view the size, location, and venous drainage of the sequestration. Immobilisation of the feeding artery was performed using a stainless steel (Tornado Embolization Coil, Cook Medical). Angiography was repeated at the end of the procedure to check whether the immobilisation of the artery was successful. Two observers (J.Z.R., X.W.H., with 12 and 23 years of experience, respectively, in interventional radiology), who were blinded to all clinical and previous imaging results, identified and analysed all pulmonary sequestration together.
Radiol med (2014) 119:27–32
Assessment method The following parameters were used to assess the anatomy of the PS and the suitability for endovascular treatment: 1.
2.
3.
The visualisation and exact location of the PS, categorised as poor visualisation or misinterpretation, ambiguous visualisation, or precise visualisation. The size and the number of aberrant systemic arteries, which were given a classification of poor visualisation, ambiguous visualisation, or precise visualisation. The feasibility of endovascular treatment on the basis of the PS anatomy. This was classified as insufficient information provided, endovascular treatment probably possible or probably not possible, or endovascular treatment definitely possible, or definitely not possible.
The treatment which was actually carried out was recorded in each case. Three senior radiologists (G.H.H., S.W.Y., and J.B.G., with 11, 16, and 25 years of experience respectively, in radiology) retrospectively analysed these parameters independently using 64-row CTA and resolved differences in assessment by means of consensus. The source images, MIPs, MPR, and VR were presented on-screen, thus allowing for the adjustment of the appropriate threshold of the window width and level. In the presence of interobserver discrepancies in the detection of PS, a consensus or a majority decision was obtained. In the case of surgery, direct confirmation was obtained by means of visualisation of the aneurysm. In the case of endovascular treatment, indirect confirmation was partially provided using the following two additional parameters, which were evaluated using MPR: 1.
2.
The possibility of obtaining a view on CTA of the aberrant systemic artery in PS in relation to the aorta that could be reproduced on the C arm. This was classified as either possible or impossible. Such a view, as used to carry out endovascular treatment, was thus referred to as the working view. The accuracy of measurements of the size of the aberrant systemic artery in choosing the diameter of the first coil to be placed in the PS. This parameter was classified as the correct or incorrect choice of coil.
Statistical analyses The categorical demographic and basic characteristic variables, expressed as numbers and percentages, were compared using the Chi squared test. Continuous variables were expressed as mean (±SD) and compared using an unpaired t test, if normally distributed. Descriptive statistics were performed on two levels: patient by patient (pulmonary sequestration absent or present, per patient)
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and artery by artery. The diagnostic performance parameters of CTA for the diagnosis of pulmonary sequestration compared with those of DSA [that is, accuracy, sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV)] were expressed as percentages (95 % CI). Interobserver reliability with percentages of agreement between the observer evaluations of the CTA images was calculated with kappa (j) statistics. Statistical analyses were performed using SPSS (version 13.0, SPSS Inc., Chicago, IL, USA).
Results Visualisation and location of PS The cases of PS were seen in cystic (n = 5), solid (n = 22), or cystic–solid lesions (n = 11) with a maximum diameter of 1.5–12 cm on plain CT scan. There was no enhancement in two patients with cystic lesions while cystic wall enhancement was seen in the other three patients. Obvious enhancement was present in all patients with solid lesions. The remaining 11 patients with cystic– solid lesions exhibited enhancement in the solid part and no enhancement in the cyst. CTA revealed 38 cases of PS in 38 patients, and 7 patients with no demonstrable PS. The location and classification of the cases of PS are summarised in Table 1. Aberrant systemic arteries originating from the thoracic artery were evident in 38 patients, and no aberrant systemic artery was exhibited in the remaining 7 patients. DSA or surgery results According to the reference standard, PS was detected in 38 patients and 7 patients had no demonstrable PS. DSA revealed 46 aberrant systemic arteries in 38 of the 44 patients: in 2 patients, 3 arteries were detected; 4 patients each had 2 arteries detected; and a single artery was detected in 32 patients. Diagnostic performance of CTA The diagnostic accuracy, sensitivity, specificity, PPV, and NPV of CTA in the patient-based and aberrant systemic artery-based evaluation on CTA are detailed in Table 2. Single-patient sample images acquired with CTA and DSA are shown in Fig. 1. CTA revealed 38 instances of PS in 38 patients, and 7 patients were shown to have no demonstrable PS. CTA also revealed 45 aberrant systemic arteries in 38 of the 45 patients: in 1 patient, 3 arteries were detected; 5 patients each had 2 arteries detected; and a single artery was detected in 32 patients. One of three
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Table 2 Diagnostic performance of CTA for the detection of pulmonary sequestration using DSA or surgery in the patient-based and aberrant systemic artery-based evaluation N
TP
TN
FP
FN
j
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
Accuracy (%)
37
7
0
1
0.89–1.0
97.4 (37/38)
100
100
87.5 (7/8)
97.8 (44/45)
Patient-based evaluation All patients
45
Aneurysm-based evaluation All arteries
53
45
7
0
1
0.89–1.0
97.8 (45/46)
100
100
87.5 (7/8)
98.1 (52/53)
Single artery
39
32
7
0
0
0.87–1.0
100
100
100
100
100
Multiple arteries
21
13
7
0
1
1.0
92.9 (13/14)
100
100
87.5 (7/8)
95.0 (20/21)
TP true-positive, TN true-negative, FP false-positive, FN false-negative, PPV positive predictive value, NPV negative predictive value
Fig. 1 Pulmonary sequestration in the right lower lobe of a 3-day-old boy. a Axial multiplanar reconstruction (MPR) image demonstrates a homogenous solid mass in the posterobasal segment of the right lower lobe with an aberrant systemic artery (arrow). b Coronal maximum intensity projection (MIP) exhibits an aberrant systemic artery (arrow) arising from the hepatic artery supplying the mass in the right lower lobe. c Pre-embolisation aortography shows the aberrant artery (arrow) from the hepatic artery. d Post-embolisation angiography confirms complete occlusion of the aberrant artery with coils (arrow)
aberrant systemic arteries detected in one patient was falsenegative on CTA. Potential for endovascular treatment In 38 patients with PS, MPR images provided sufficient information on the site, number and size of aberrant
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systemic arteries in 37 (97 %) of 38 patients, and insufficient information in one patient with multiple aberrant systemic arteries. According to CTA findings, endovascular treatment was certainly possible in 37 (97 %) of 38 patients and probably possible in one (3 %). In fact, endovascular treatment was performed in 36 patients with PS, and 2 patients opted for surgery due to other complications.
Radiol med (2014) 119:27–32
The surgery carried out in these patients demonstrated that CTA findings about the aberrant systemic arteries had been correct. View for performing endovascular treatment (working view) In 36 patients with PS where endovascular treatment was possible, MPR analysis allowed us to easily find the working view that clearly demonstrated the location of the aberrant systemic artery and could be used to perform endovascular treatment. This working view was then reproduced on the C arm. The resultant CTA series was always similar to the DSA view and satisfactory for performing endovascular treatment. Size of the aberrant systemic artery In the 36 patients with PSs suitable for coil embolisation, measurements the size of the aberrant systemic artery were performed on MPR. These measurements facilitated our choice of coil. The diameter of the coil was chosen according to the largest diameter of the aberrant systemic artery on MPR. The coil selected was appropriate in 35 (97 %) of 36 treated patients with PS.
Discussion This prospective study was based on our hypothesis that CTA could replace DSA as a reliable diagnostic and pretreatment planning tool for patients with PS. In this study, the high accuracy ([95 %) and sensitivity ([95 %) of CTA for detecting PS was equivalent to the gold standard, DSA, indicating that CTA cannot only replace the DSA for the diagnosis of PS but can also differentiate PS from other similar conditions. When compared with actual treatment decisions made using DSA or surgery, CTA provided an effective diagnostic performance, delineating aberrant systemic arteries and enabling appropriate coil selection prior to embolisation in 37 of 38 patients with PS. This suggests the potential of CTA as an effective tool which could be used alone in treatment planning for most patients with PS. Pulmonary sequestration is a rare congenital malformation that represents 0.15–6.4 % of all pulmonary malformations [14, 15]. Traditionally, the diagnosis of PS requires arteriography to identify abnormal systemic vessels feeding the abnormal portion of the lung and to provide valuable information for preoperative planning [2, 16]. Recently, the quality and accuracy of CTA, particularly helical multi-slice CTA, has been seen to be approaching that of catheter DSA, which has been the gold
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standard diagnostic tool in patients with pulmonary malformations. The advantages of CTA are that, compared with DSA, it is noninvasive, has a much lower risk of complication or morbidity, can be performed much more quickly, requires fewer resources (staffing, equipment, and cost), is not painful to the patient, does not require sedation (in most patients), and is more suitable for critically ill or unstable patients. Conversely, while DSA can clearly identify aberrant feeding arteries in PS, it is invasive, associated with radiation, time-consuming, relatively expensive, and requires hospitalisation. Although there have been many reports in the literature that assess the validity of CTA as a diagnostic technique for the detection of PS, few have evaluated the clinical implications of a protocol that uses CTA instead of DSA as a diagnostic and pre-treatment planning tool. If CTA is to serve as a non-invasive replacement for DSA in pre-treatment planning, it must provide precise visualisation of the site and number of aberrant systemic arteries and their relationships to the aorta. In addition, it is essential to know the shape and the size of the feeding artery before performing endovascular treatment using coil embolisation. Our study showed that therapeutic decisions could be based on information provided by CTA alone in most cases because 64-section CTA is capable of three-dimensional reconstructions in unlimited projections. We found that certain reconstruction algorithms, such as VR reconstructed images and MPRs, may provide useful anatomical information about the PS that closely approximates intraoperative findings. In the investigation of a suspected case of PS, CT, and CTA have two principal objectives: to rule out other pathologies and to confirm the presence of an anomalous arterial supply [4, 9, 16]. CTA is able not only to identify the systemic artery supply, but also yields the maximum information about the lung parenchyma including the airways. Conditions, such as bronchiectasis, atelectasis (including that due to an endobronchial lesion), other bronchopulmonary foregut malformations, and bronchial atresia, can clinically and radiographically resemble sequestration. These are not amenable to diagnosis by colour Doppler sonography, magnetic resonance imaging or DSA, whereas they can be detected with high accuracy by CT [17]. In other words, CTA is the sole diagnostic method which can delineate the origin and course of anomalous systemic arteries and venous drainage accurately as well as evaluating abnormal lung parenchyma and the airways. Recently, endovascular coil embolisation has provided a less invasive alternative to surgery [18–23], especially for neonates or children. These methods can be used to protect the lungs from excessive intraoperative bronchial blood
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flow. Selective coiling is also the preferred treatment for PS at our institution. While CTA facilitates a simple and reproducible angiographic protocol, DSA has been part of our angiographic protocol in undetermined cases. For endovascular treatment, one must use a twodimensional view that clearly depicts the aberrant systemic artery in relation to adjacent vessels and could be used to perform treatment in optimal conditions. In this study, CTA allowed precise analysis of the anatomy of PS in all 22 cases. This two-dimensional working view consistently corresponded well with the DSA findings and was satisfactory in supporting endovascular treatment. In addition, the choice of coil diameter is an important factor in ensuring correct deployment of the coil into the proximal of the aberrant systemic artery. Precise measurements of the size of the aberrant systemic artery that were obtained by using MPRs on CTA imaging helped us in this important and difficult choice, especially in determining the coil diameter. In this study, all patients were successfully treated with coil embolisation without the occurrence of complications. The study had some limitations. First, this is a singlecentre study, and the patient population was small. The small sample prevents us from generalising the results. Second, CTA scanning involves exposure of the patient to ionising radiation and the administration of intravenous contrast material. Last, the dose of the contrast material may be high for paediatric patients; therefore, a more extensive evaluation of patient dose should be performed taking age into consideration. In conclusion, 64-row CTA appears to be effective in terms of supporting accurate diagnosis and pre-treatment planning in PS. CTA is not only able to provide clear visualisation of aberrant systemic arteries but also provides detailed images of abnormal lung parenchyma and the airways. Conflict of interest Jian-Zhuang Ren, Kai Zhang, Guo-Hao Huang, Meng-Fan Zhang, Peng-Li Zhou, Xin-Wei Han, Xu-Hua Duan, Zhen Li declare no conflict of interest.
References 1. Felker RE, Tonkin ILD (1990) Imaging of pulmonary sequestration. AJR 154:241–249 2. Franco J, Aliaga R, Domingo ML, Plaza P (1998) Diagnosis of pulmonary sequestration by spiral CT angiography. Thorax 53:1089–1092 3. Ikezoe J, Murayama S, Godwin JD (1990) Bronchopulmonary sequestration: CT assessment. Radiology 176:375–379
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Radiol med (2014) 119:27–32 4. Kang M, Khandelwal N, Ojili V et al (2006) Multidetector CT angiography in pulmonary sequestration. J Comput Assist Tomogr 30:926–932 5. Wei Y, Li F (2011) Pulmonary sequestration: a retrospective analysis of 2625 cases in China. Eur J Cardiothorac Surg 40:e39–e42 6. Scialpi M, Cappabianca S, Rotondo A et al (2011) Pulmonary congenital cystic disease in adults. Spiral computed tomography findings with pathologic correlation and management. Radiol Med 115:539–550 7. Yu H, Li HM, Liu SY, Xiao XS (2010) Diagnosis of arterial sequestration using multidetector CT angiography. Eur J Radiol 76:274–278 8. Clemente A, Morra A (2007) Use of multidetector CT angiography and 3D postprocessing in a case of pulmonary sequestration. Clin Imaging 31:210–213 9. Schussler JM, Dockery WD, Gilbey JG, Lal VR (2007) An alternate route: 64-slice CT diagnosis of pulmonary pseudosequestration. Am J Med 120:23–25 10. Siegel MJ (2003) Multiplanar and three-dimensional multidetector row CT of thoracic vessels and airways in the pediatric population. Radiology 229:641–650 11. Lee EY, Siegel MJ, Sierra LM, Foglia RP (2004) Evaluation of angioarchitecture of pulmonary sequestration in pediatric patients using 3D MDCT angiography. AJR 183:183–188 12. Hang JD, Guo QY, Chen CX, Chen LY (1996) Imaging approach to the diagnosis of pulmonary sequestration. Acta Radiol 37:883–888 13. Takemura R, Ohnishi S, Takahashi S, Miyagishima T (2010) Pulmonary sequestration diagnosed by three-dimensional reconstruction computed tomography. Intern Med 49:1683–1684 14. Savic B, Birtel FJ, Tholen W et al (1979) Lung sequestration: report of seven cases and review of 540 published cases. Thorax 34:96–101 15. Van Raemdonck D, De Boeck K, Devlieger H et al (2001) Pulmonary sequestration: a comparison between pediatric and adult patients. Eur J Cardiothorac Surg 19:388–395 16. Fumino S, Iwai N, Kimura O et al (2007) Preoperative evaluation of the aberrant artery in intralobar pulmonary sequestration using multidetector computed tomography angiography. J Pediatr Surg 42:1776–1779 17. Frush DP, Donnelly LF (1997) Pulmonary sequestration spectrum: a new spin with helical CT. AJR 1693:679–682 18. Chien KJ, Huang TC, Lin CC et al (2009) Early and late outcomes of coil embolization of pulmonary sequestration in children. Circ J 73:938–942 19. Park ST, Yoon CH, Sung KB et al (1998) Pulmonary sequestration in a newborn infant: treatment with arterial embolization. J Vasc Interv Radiol 9:648–650 20. Leoncini G, Rossi UG, Ferro C, Chessa L (2011) Endovascular treatment of pulmonary sequestration in adults using Amplatzer vascular plugs. Interact Cardiovasc Thorac Surg 12:98–100 21. Curros F, Chigot V, Emond S et al (2000) Role of embolisation in the treatment of bronchopulmonary sequestration. Pediatr Radiol 30:769–773 22. Tokel K, Boyvat F, Varan B (2000) Coil embolization of pulmonary sequestration in two infants: a safe alternative to surgery. AJR 175:993–995 23. Ganeshan A, Freedman J, Hoey ET et al (2010) Transcatheter coil embolisation: a novel definitive treatment option for intralobar pulmonary sequestration. Heart Lung Circ 19:561–565
CHEST RADIOLOGY
Assessment of 64-row computed tomographic angiography for diagnosis and pretreatment planning in pulmonary sequestration Jian-Zhuang Ren • Kai Zhang • Guo-Hao Huang • Meng-Fan Zhang • Peng-Li Zhou • Xin-Wei Han • Xu-Hua Duan • Zhen Li
Received: 22 April 2012 / Accepted: 25 September 2012 / Published online: 15 November 2013 Ó Italian Society of Medical Radiology 2013
Abstract Purpose This study was done to evaluate the clinical implications and results of a prospective protocol using 64-row computed tomographic angiography (CTA) for diagnosis and pre-treatment planning in pulmonary sequestration (PS). Materials and methods Forty-five patients with suspected PS were referred for CTA examination. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of measures used to detect PS were determined by patient-based and aberrant systemic artery-based evaluations. The location, the size and the number of aberrant systemic arteries, and the feasibility of endovascular treatment were analysed. The capability of CTA to provide a working view and the accuracy of measurements in choosing a coil were also assessed. Results Digital subtraction angiography and/or surgery revealed PS in 38 patients, and 7 patients had no PS. The patient-based evaluation yielded an accuracy of 97.8 %, sensitivity of 97.4 %, specificity of 100 %, PPV of 100 % and NPV of 87.5 %, in the detection of PS. CTA clearly depicted the PS in all 38 patients, and the aberrant systemic artery was accurately demonstrated in 37 out of 38 patients where endovascular treatment was possible. Working views for endovascular treatment were found in all patients with PS, and the choice of coil was correct in 37 out of 38 patients using CTA. K. Zhang is the Co-first author. J.-Z. Ren (&) K. Zhang G.-H. Huang M.-F. Zhang P.-L. Zhou X.-W. Han X.-H. Duan Z. Li Department of Interventional Radiology, The First Affiliated Hospital, Zhengzhou University, No.1, East Jian She Road, Zhengzhou 450052, Henan, Republic of China e-mail: [email protected]
Conclusions 64-row CTA appears to be effective in terms of supporting accurate diagnosis and pre-treatment planning in PS. CTA is not only able to provide clear visualisation of aberrant systemic arteries but also provides detailed images of abnormal lung parenchyma and the airways. Keywords Pulmonary sequestration Angiography DSA Endovascular
Introduction Pulmonary sequestration (PS) is a rare congenital pulmonary disorder defined by an area of dysplastic and nonfunctioning pulmonary tissue which has an anomalous systemic blood supply [1]. Conventional digital subtraction angiography (DSA) is considered the gold standard for the diagnosis of PS [2]. In recent years, less invasive imaging techniques, particularly helical multislice computed tomographic angiography (CTA), have proved to be equally effective and safer alternatives to DSA [3–13]. CTA can provide the precise visualisation of the site, size and number of aberrant systemic arteries and their relationship to the aorta, which are fundamental factors that must be assessed before choosing between endovascular and neurosurgical treatments. Previous reports in the literature have assessed the sensitivity and specificity of CTA compared with DSA [3– 13]. However, these investigations have not analysed the clinical implications of a protocol that replaces DSA with CTA as the only diagnostic and pre-treatment planning tool for patients with PS. Therefore, the purpose of the current study was to evaluate the clinical implications and clinical results of a prospective protocol using 64-row CTA for the diagnosis and endovascular treatment of PS.
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Radiol med (2014) 119:27–32
Materials and methods Study design The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent before participation. From May 2008 to December 2011, patients with suspected PS detected by CTA underwent coil embolisation, surgical resection, or conservative treatment. DSA or surgery was performed after CTA to confirm the diagnosis of PS. A total of 45 consecutive patients were enrolled in the study. The patients included 28 males and 17 females with a mean age of 4.95 ± 9.00 years (range, 1 day to 45 years). The basic characteristics of the study patients are summarised in Table 1. 14 patients presented with recurrent fever, cough, and pulmonary infection, 3 with recurrent haemoptysis, and the remaining 28 patients were asymptomatic. Image acquisition CTA All CTA examinations were performed using a 64-row CT scanner (light speed VCT or Discovery CT750 HD, GE Healthcare) with a bolus tracking system. The smart
Table 1 Baseline characteristics of 45 patients with pulmonary sequestration (PS) Characteristic
All patients (n = 45)
PS (n = 38)
Non-PS (n = 7)
Age (years)
4.95 ± 9.00
3.78 ± 8.64
11.28 ± 8.90
Male sex-no. (%)
28 (62.2.2)
24 (63.2.5)
4 (57.1)
Location-no. (%) Left lower lobe
28 (62.2)
25 (65.8)
3 (42.9)
17 (37.8)
13 (34.2)
4 (57.1)
Intralobar
–
22 (4.2)
-
Extralobar
-
16 (4.2)
-
Right lower lobe Classification-no. (%)
Aberrant systemic artery-no. (%) Descending aorta
-
28
-
Abdominal aorta
-
10
-
Single artery
-
32
-
Multiple artery
-
6
-
Draining vein-no. (%) Pulmonary vein
-
26
-
Azygos vein
-
9
-
Hemiazygos vein
-
1
-
Portal vein
-
2
-
123
preset scan technique was used for enhanced CTA with the following parameters: 0.625 mm 9 64 slice, 120 kVp, 100–600 mA, 1.375:1 helical pitch, and with an acquisition time of 25.6 s. The standard dose for enhanced CTA was 0.7 ml/kg body weight in addition to 40 ml normal saline, and the contrast material was administered using a power injector at a rate of 4 ml/s through a 22-gauge needle in the antecubital vein. When the concentration of contrast medium in the ascending aorta reached 100 HU, the CT device automatically scanned from the apex of the lung to the upper abdomen. The acquired image data sets were then transferred to a workstation (GE AW4.3 or GE AW4.4, GE Medical), where 3D image reconstruction, comprising oblique, coronal and sagittal maximum-intensity projection (MIP), multiplanar reconstruction (MPR), and three-dimensional volume-rendered (VR) images of airway and thoracic vascular structures, was performed with a 732 9 732 matrix. Each patient was assessed for PS after a collateral artery originating from the aorta was identified in the scans. The site of origin, distribution, and course of PS were evaluated on the basis of MPR, MIP, and VR by adjusting the value of translucency or slab thickness. The diameter of PS was measured on MPR. The pulmonary arteries and veins of the affected lung were also evaluated. Each segmental bronchus of the involved lung was reconstructed using MPR and minimum intensity projections (MIP). The number and course of branches and the lung volume were also evaluated. DSA DSA was carried out by an interventional radiologist after CTA examinations. Conventional 2D-DSA was performed on a monoplanar unit (Axiom Artis VB22N, Siemens) with a 1,024 9 1,024 matrix and a 17 9 20 cm field of view. The access routes for angiography were the umbilical artery (neonates) and the femoral artery. After performing a complete haemodynamic evaluation, an initial aortogram was obtained to show the arterial map of the systemic feeders. The abnormal vessels were then selectively catheterised with a 4- or 5-Fr catheter. Angiography was carried out to view the size, location, and venous drainage of the sequestration. Immobilisation of the feeding artery was performed using a stainless steel (Tornado Embolization Coil, Cook Medical). Angiography was repeated at the end of the procedure to check whether the immobilisation of the artery was successful. Two observers (J.Z.R., X.W.H., with 12 and 23 years of experience, respectively, in interventional radiology), who were blinded to all clinical and previous imaging results, identified and analysed all pulmonary sequestration together.
Radiol med (2014) 119:27–32
Assessment method The following parameters were used to assess the anatomy of the PS and the suitability for endovascular treatment: 1.
2.
3.
The visualisation and exact location of the PS, categorised as poor visualisation or misinterpretation, ambiguous visualisation, or precise visualisation. The size and the number of aberrant systemic arteries, which were given a classification of poor visualisation, ambiguous visualisation, or precise visualisation. The feasibility of endovascular treatment on the basis of the PS anatomy. This was classified as insufficient information provided, endovascular treatment probably possible or probably not possible, or endovascular treatment definitely possible, or definitely not possible.
The treatment which was actually carried out was recorded in each case. Three senior radiologists (G.H.H., S.W.Y., and J.B.G., with 11, 16, and 25 years of experience respectively, in radiology) retrospectively analysed these parameters independently using 64-row CTA and resolved differences in assessment by means of consensus. The source images, MIPs, MPR, and VR were presented on-screen, thus allowing for the adjustment of the appropriate threshold of the window width and level. In the presence of interobserver discrepancies in the detection of PS, a consensus or a majority decision was obtained. In the case of surgery, direct confirmation was obtained by means of visualisation of the aneurysm. In the case of endovascular treatment, indirect confirmation was partially provided using the following two additional parameters, which were evaluated using MPR: 1.
2.
The possibility of obtaining a view on CTA of the aberrant systemic artery in PS in relation to the aorta that could be reproduced on the C arm. This was classified as either possible or impossible. Such a view, as used to carry out endovascular treatment, was thus referred to as the working view. The accuracy of measurements of the size of the aberrant systemic artery in choosing the diameter of the first coil to be placed in the PS. This parameter was classified as the correct or incorrect choice of coil.
Statistical analyses The categorical demographic and basic characteristic variables, expressed as numbers and percentages, were compared using the Chi squared test. Continuous variables were expressed as mean (±SD) and compared using an unpaired t test, if normally distributed. Descriptive statistics were performed on two levels: patient by patient (pulmonary sequestration absent or present, per patient)
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and artery by artery. The diagnostic performance parameters of CTA for the diagnosis of pulmonary sequestration compared with those of DSA [that is, accuracy, sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV)] were expressed as percentages (95 % CI). Interobserver reliability with percentages of agreement between the observer evaluations of the CTA images was calculated with kappa (j) statistics. Statistical analyses were performed using SPSS (version 13.0, SPSS Inc., Chicago, IL, USA).
Results Visualisation and location of PS The cases of PS were seen in cystic (n = 5), solid (n = 22), or cystic–solid lesions (n = 11) with a maximum diameter of 1.5–12 cm on plain CT scan. There was no enhancement in two patients with cystic lesions while cystic wall enhancement was seen in the other three patients. Obvious enhancement was present in all patients with solid lesions. The remaining 11 patients with cystic– solid lesions exhibited enhancement in the solid part and no enhancement in the cyst. CTA revealed 38 cases of PS in 38 patients, and 7 patients with no demonstrable PS. The location and classification of the cases of PS are summarised in Table 1. Aberrant systemic arteries originating from the thoracic artery were evident in 38 patients, and no aberrant systemic artery was exhibited in the remaining 7 patients. DSA or surgery results According to the reference standard, PS was detected in 38 patients and 7 patients had no demonstrable PS. DSA revealed 46 aberrant systemic arteries in 38 of the 44 patients: in 2 patients, 3 arteries were detected; 4 patients each had 2 arteries detected; and a single artery was detected in 32 patients. Diagnostic performance of CTA The diagnostic accuracy, sensitivity, specificity, PPV, and NPV of CTA in the patient-based and aberrant systemic artery-based evaluation on CTA are detailed in Table 2. Single-patient sample images acquired with CTA and DSA are shown in Fig. 1. CTA revealed 38 instances of PS in 38 patients, and 7 patients were shown to have no demonstrable PS. CTA also revealed 45 aberrant systemic arteries in 38 of the 45 patients: in 1 patient, 3 arteries were detected; 5 patients each had 2 arteries detected; and a single artery was detected in 32 patients. One of three
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Table 2 Diagnostic performance of CTA for the detection of pulmonary sequestration using DSA or surgery in the patient-based and aberrant systemic artery-based evaluation N
TP
TN
FP
FN
j
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
Accuracy (%)
37
7
0
1
0.89–1.0
97.4 (37/38)
100
100
87.5 (7/8)
97.8 (44/45)
Patient-based evaluation All patients
45
Aneurysm-based evaluation All arteries
53
45
7
0
1
0.89–1.0
97.8 (45/46)
100
100
87.5 (7/8)
98.1 (52/53)
Single artery
39
32
7
0
0
0.87–1.0
100
100
100
100
100
Multiple arteries
21
13
7
0
1
1.0
92.9 (13/14)
100
100
87.5 (7/8)
95.0 (20/21)
TP true-positive, TN true-negative, FP false-positive, FN false-negative, PPV positive predictive value, NPV negative predictive value
Fig. 1 Pulmonary sequestration in the right lower lobe of a 3-day-old boy. a Axial multiplanar reconstruction (MPR) image demonstrates a homogenous solid mass in the posterobasal segment of the right lower lobe with an aberrant systemic artery (arrow). b Coronal maximum intensity projection (MIP) exhibits an aberrant systemic artery (arrow) arising from the hepatic artery supplying the mass in the right lower lobe. c Pre-embolisation aortography shows the aberrant artery (arrow) from the hepatic artery. d Post-embolisation angiography confirms complete occlusion of the aberrant artery with coils (arrow)
aberrant systemic arteries detected in one patient was falsenegative on CTA. Potential for endovascular treatment In 38 patients with PS, MPR images provided sufficient information on the site, number and size of aberrant
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systemic arteries in 37 (97 %) of 38 patients, and insufficient information in one patient with multiple aberrant systemic arteries. According to CTA findings, endovascular treatment was certainly possible in 37 (97 %) of 38 patients and probably possible in one (3 %). In fact, endovascular treatment was performed in 36 patients with PS, and 2 patients opted for surgery due to other complications.
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The surgery carried out in these patients demonstrated that CTA findings about the aberrant systemic arteries had been correct. View for performing endovascular treatment (working view) In 36 patients with PS where endovascular treatment was possible, MPR analysis allowed us to easily find the working view that clearly demonstrated the location of the aberrant systemic artery and could be used to perform endovascular treatment. This working view was then reproduced on the C arm. The resultant CTA series was always similar to the DSA view and satisfactory for performing endovascular treatment. Size of the aberrant systemic artery In the 36 patients with PSs suitable for coil embolisation, measurements the size of the aberrant systemic artery were performed on MPR. These measurements facilitated our choice of coil. The diameter of the coil was chosen according to the largest diameter of the aberrant systemic artery on MPR. The coil selected was appropriate in 35 (97 %) of 36 treated patients with PS.
Discussion This prospective study was based on our hypothesis that CTA could replace DSA as a reliable diagnostic and pretreatment planning tool for patients with PS. In this study, the high accuracy ([95 %) and sensitivity ([95 %) of CTA for detecting PS was equivalent to the gold standard, DSA, indicating that CTA cannot only replace the DSA for the diagnosis of PS but can also differentiate PS from other similar conditions. When compared with actual treatment decisions made using DSA or surgery, CTA provided an effective diagnostic performance, delineating aberrant systemic arteries and enabling appropriate coil selection prior to embolisation in 37 of 38 patients with PS. This suggests the potential of CTA as an effective tool which could be used alone in treatment planning for most patients with PS. Pulmonary sequestration is a rare congenital malformation that represents 0.15–6.4 % of all pulmonary malformations [14, 15]. Traditionally, the diagnosis of PS requires arteriography to identify abnormal systemic vessels feeding the abnormal portion of the lung and to provide valuable information for preoperative planning [2, 16]. Recently, the quality and accuracy of CTA, particularly helical multi-slice CTA, has been seen to be approaching that of catheter DSA, which has been the gold
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standard diagnostic tool in patients with pulmonary malformations. The advantages of CTA are that, compared with DSA, it is noninvasive, has a much lower risk of complication or morbidity, can be performed much more quickly, requires fewer resources (staffing, equipment, and cost), is not painful to the patient, does not require sedation (in most patients), and is more suitable for critically ill or unstable patients. Conversely, while DSA can clearly identify aberrant feeding arteries in PS, it is invasive, associated with radiation, time-consuming, relatively expensive, and requires hospitalisation. Although there have been many reports in the literature that assess the validity of CTA as a diagnostic technique for the detection of PS, few have evaluated the clinical implications of a protocol that uses CTA instead of DSA as a diagnostic and pre-treatment planning tool. If CTA is to serve as a non-invasive replacement for DSA in pre-treatment planning, it must provide precise visualisation of the site and number of aberrant systemic arteries and their relationships to the aorta. In addition, it is essential to know the shape and the size of the feeding artery before performing endovascular treatment using coil embolisation. Our study showed that therapeutic decisions could be based on information provided by CTA alone in most cases because 64-section CTA is capable of three-dimensional reconstructions in unlimited projections. We found that certain reconstruction algorithms, such as VR reconstructed images and MPRs, may provide useful anatomical information about the PS that closely approximates intraoperative findings. In the investigation of a suspected case of PS, CT, and CTA have two principal objectives: to rule out other pathologies and to confirm the presence of an anomalous arterial supply [4, 9, 16]. CTA is able not only to identify the systemic artery supply, but also yields the maximum information about the lung parenchyma including the airways. Conditions, such as bronchiectasis, atelectasis (including that due to an endobronchial lesion), other bronchopulmonary foregut malformations, and bronchial atresia, can clinically and radiographically resemble sequestration. These are not amenable to diagnosis by colour Doppler sonography, magnetic resonance imaging or DSA, whereas they can be detected with high accuracy by CT [17]. In other words, CTA is the sole diagnostic method which can delineate the origin and course of anomalous systemic arteries and venous drainage accurately as well as evaluating abnormal lung parenchyma and the airways. Recently, endovascular coil embolisation has provided a less invasive alternative to surgery [18–23], especially for neonates or children. These methods can be used to protect the lungs from excessive intraoperative bronchial blood
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flow. Selective coiling is also the preferred treatment for PS at our institution. While CTA facilitates a simple and reproducible angiographic protocol, DSA has been part of our angiographic protocol in undetermined cases. For endovascular treatment, one must use a twodimensional view that clearly depicts the aberrant systemic artery in relation to adjacent vessels and could be used to perform treatment in optimal conditions. In this study, CTA allowed precise analysis of the anatomy of PS in all 22 cases. This two-dimensional working view consistently corresponded well with the DSA findings and was satisfactory in supporting endovascular treatment. In addition, the choice of coil diameter is an important factor in ensuring correct deployment of the coil into the proximal of the aberrant systemic artery. Precise measurements of the size of the aberrant systemic artery that were obtained by using MPRs on CTA imaging helped us in this important and difficult choice, especially in determining the coil diameter. In this study, all patients were successfully treated with coil embolisation without the occurrence of complications. The study had some limitations. First, this is a singlecentre study, and the patient population was small. The small sample prevents us from generalising the results. Second, CTA scanning involves exposure of the patient to ionising radiation and the administration of intravenous contrast material. Last, the dose of the contrast material may be high for paediatric patients; therefore, a more extensive evaluation of patient dose should be performed taking age into consideration. In conclusion, 64-row CTA appears to be effective in terms of supporting accurate diagnosis and pre-treatment planning in PS. CTA is not only able to provide clear visualisation of aberrant systemic arteries but also provides detailed images of abnormal lung parenchyma and the airways. Conflict of interest Jian-Zhuang Ren, Kai Zhang, Guo-Hao Huang, Meng-Fan Zhang, Peng-Li Zhou, Xin-Wei Han, Xu-Hua Duan, Zhen Li declare no conflict of interest.
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