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Vascular imaging findings with high-pitch low-dose dual-source CT in atypical Kawasaki disease.

Kawasaki disease (KD) is an acute, febrile, self-limited vasculitis that affects small- and medium-sized arteries, with a predilection for the coronary arteries (1). The disease mainly affects infants and children younger than 5 years of age. The etiology of KD is unknown, and there are no specific diagnostic tests (2). The diagnosis of this disease is ideally made by clinical criteria according to the American Heart Association. Typical or classical Kawasaki (TKD) disease can be diagnosed if a fever lasts longer than 5 days and if a patient has 4 of the 5 clinical features. However, according to the Japanese guidelines, atypical or incomplete Kawasaki disease (AKD) is defined as the presence of 4 or fewer of the main findings of KD regardless of the presence or absence of coronary artery aneurysm (CAA).

In some cases with unexplained prolonged fever, the clinical features may be insufficient for the diagnosis of TKD. In this instance, AKD may be considered. Determining the presence of aneurysms in small- and medium-sized arteries is quite important in the diagnosis of AKD (3). CAAs are seen in up to 25% of cases, and systemic artery aneurysms (SAA) are seen in 2% (4). Especially in atypical cases, cardiac and other vascular complications can be more frequently seen because the diagnosis can be delayed. Therefore, early diagnosis and treatment is very important to prevent complications (5).

There are several imaging modalities for scanning vascular structures, including echocardiography, magnetic resonance imaging (MRI), computed tomography (CT) and ultrasonography (US). In the diagnosis of AKD, each of these imaging techniques has specific handicaps. High-pitch low-dose CT angiography can be very useful in screening for CAA and associated SAA in patients with AKD.

In this article, the diagnosis and clinical features of AKD are presented with high-pitch low-dose dual-source CT angiography.

Methods

Patient selection

The study subjects seen at our institution between 2012 and 2017 with suspected AKD who did not have enough clinical features for a diagnosis of TKD according to the American Heart Association diagnostic guidelines were included in our study. We evaluated 17 consecutive patients who were referred to us by our center or an outside center at the pediatric cardiology clinic. High-pitch low-dose CT angiography was performed in all patients because systemic aneurysms can be present without CAA. Each CT angiography study was examined for aneurysms and occlusive disease. The age of the patients ranged from 2 months to 11.3 years, with a mean age of 3 years. Seven of the patients were male. Six patients did not have any aneurysms and were therefore excluded. This study was approved by our institutional ethics committee (the decision number of ethics committee approval: B.30.2.ATA.0.01.00/91), and informed consent was obtained from the families of all patients.

CT protocol

All high-pitch low-dose CT examinations were performed on a dual source CT system (Definition Flash, Siemens Healthcare). The scans were performed with free-breathing, in a craniocaudal direction. CT parameters were as follows: 0.28 s gantry rotation time, 128x0.6 mm slice acquisition by z-flying focal spot technique, weight adapted setting for tube current (50 effective mAs for patients <5 kg body weight, 80 effective mAs for patients 5-10 kg body weight, 100 effective mAs for patients >10 kg body weight) at 80 kV tube voltage, 411 mm/s table speeds. The high pitch was 3.4 for CT examinations.

Contrast agent (lopromide, 350 mg I/mL, Ultravist, Bayer HealthCare) was injected via the peripheral vein at a volume of 1.5 mL/kg body weight with a chaser saline of 1.0 mL/kg body weight. After the contrast material and saline were injected, the scan was started immediately without delay. Vac-lok cushions were used for the immobilization of patients. A reconstruction of the images was conducted with a slice thickness of 0.75 mm and increment of 0.5 mm.

We evaluated a broad range of anatomic areas on the CT. The examination was usually focused on clinical symptoms of the patients as well as the coronary arteries such as the branches of the abdominal aorta and extremity arteries. Generally positive findings were detected at symptomatic areas and in the different arteries. Each of the scans was finished in 1-1.5s without any complications.

All of the images were assessed in consensus by two radiologists who were blinded to the information about the patients and who had more than 4 years of experience at a workstation (Syngo Via, Siemens Healthcare).

Results

Multiple CAA and several SAA were found in 11 patients (age range, 2 months to 11.3 years; mean age, 4.2 years; median age, 26 months; 7 males), and AKD was diagnosed in these patients (Table). CAA was present in 4 patients without SAA (36%) (Fig. 1). SAA was present in 4 patients without CAA (36%). Three patients had both SAA and CAA (27%).

Two patients had sterile pyuria, proteinuria and flank pain. CT angiography demonstrated the presence of renal artery aneurysms without CAA (18%) (Fig. 2). Pulmonary artery aneurysm was present in addition to CAA in one patient (9%) (Fig. 3).

Axillary artery aneurysms were found in two patients (18%). In one patient with axillary artery aneurysm, CAA was also present. In the other patient, the axillary artery aneurysm was the only arterial aneurysm that was identified on CT (Fig. 4). This axillary artery was thrombosed, and peripheral gangrenous features were found in this patient.

One patient had an ulnar artery aneurysm with CAA and axillary aneurysm (Fig. 5).

CT angiography showed iliac artery aneurysms in two patients (18%) (Fig. 6). In one patient, a femoral artery aneurysm was accompanied by iliac artery aneurysm and CAA (Fig. 7), and in another patient, a popliteal artery aneurysm was found along with an iliac artery aneurysm (9%) (Fig. 8).

Right iliac artery aneurysm, the largest of these aneurysms, was measured 25 mm in diameter. One of the CAAs was the smallest aneurysm, with a diameter of 4 mm.

The effective radiation dose was measured as 1.2 to 4.3 mGy depending on the patient's body weight.

Discussion

The diagnosis of TKD is easy, and treatment can be started without loss of time, while AKD has an atypical clinical presentation, and its diagnosis is very difficult. When treatment is delayed, the consequences may be disastrous. Thus, in patients with AKD, determining the presence of vascular aneurysms is crucial (4, 6). Coronary arteries are the most common location for aneurysms in patients with KD, but SAAs can also be seen on rare occurrences.

Peripheral arteries, not including abdominal and thoracic arteries, can be demonstrated with ultrasonography (3, 7). All of these peripheral arteries can be scanned with magnetic resonance angiography (MRA). However, the difficulties of showing the coronary artery by MRA are known. Contrary to CT angiography, MRA has low resolution in small aneurysms. In addition, MRA requires anesthesia and more time in young children (8). Invasive catheter angiography can detect both systemic and coronary arteries. However, invasive angiography has some disadvantages such as its invasiveness, possible complications, requirement of anesthesia and radiation exposure (9, 10).

High-pitch low-dose CT angiography is an impressive alternative imaging modality for patients with AKD. CT angiography is free-breathing, does not require anesthesia and does not depend on the user (8, 11). This technique can detect aneurysms that are missed by echocardiography (22) and can also detect more distal aneurysms that are identified with ultrasonography (13) along with SAA in any location in young children. Further, it is a noninvasive technique, and CT angiography can detect vascular aneurysms, occlusions and stenoses previously identified by invasive angiography. In addition, with this modality, the wall of the vessel can be assessed in addition to its lumen. Traditional CT angiography, unlike low dose CT angiography, is more harmful especially for young children. During routine pediatric body CT examinations, the radiation burden is 4.4-8.5 mSv (14). In our study, we used the SAFIR denoising method on work stations that maintain spatial resolution and retain diagnostic quality images. With this technique, the effective radiation dose can be decreased (1.4-4.3 mSv, main 1.9 mSv), and high-resolution images can be obtained easily and quickly (15).

Advice on high-pitch low-dose CT angiography mentions not only the diagnosis of KD but also discusses the follow-up for patients with KD. According to the American Heart Association and the Japanese Circulation Society, patients without aneurysms should be assessed with electrocardiography and echocardiography for cardiovascular risk for 5 years after disease onset. Patients with aneurysms can be examined with CT angiography (3, 16). In the Dietz et al. (17) study, the authors suggested that high-pitch low-dose CT angiography can be used at both early and late stages of monitoring for the development of stenosis.

Our study has several limitations. First, the sample size was small due to the relatively rare incidence of the disease. Second, we were not able to compare our results with other modalities because we wanted to uncover the efficiency of CT angiography. Although the radiation dose is reduced by high pitch, this imaging technique still requires radiation.

In conclusion, high-pitch low-dose CT angiography can be considered to be a noninvasive, robust and safer diagnostic imaging modality, given that this technique shows aneurysms at any location in AKD.

Conflict of interest disclosure

The authors declared no conflicts of interest.

References

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(2.) Prondzinski L. Kawasaki Disease. Radiology 1997; 203:218. [CrossRef]

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(5.) Kumar N, Mittal MK, Sinha M, Gupta A, Thukral BB. Unusual imaging presentation of infantile atypical Kawasaki disease. Indian J Radiol Imaging 2016; 26:373-376. [CrossRef]

(6.) Rowley A.H. Incomplete (atypical) Kawasaki disease. Pediatr Infect Dis J 2002; 21:563-565. [CrossRef]

(7.) Mavrogeni S, Papadopoulos G, Karanasios E, Cokkinos DV. How to image Kawasaki disease: a validation of different imaging techniques. Int J Cardiol 2008; 124:27-31. [CrossRef]

(8.) Goo HW, Park I-S, Ko JK, Kim YH. Coronary CT angiography and MR angiography of Kawasaki disease. Ped Radiol 2006; 36:697-705. [CrossRef]

(9.) Aggarwala G, Iyengar N, Burke SJ. Kawasaki disease: role of coronary CT angiography. Int J Cardiovasc Imaging 2006; 22:803-805. [CrossRef]

(10.) Kato H, Ichinose E, Yoshioka F et al. Fate of coronary aneurysms in Kawasaki disease: serial coronary angiography and long-term follow-up study. Am J Cardiol 1982; 49:1758-1766. [CrossRef]

(11.) Ghareep AN, Alkuwari M, Willington F, Szmigielski W. Kawasaki disease: diagnosis and follow-up by CT coronary angiography with the use of 128-slice dual source dual energy scanner. A case report. Pol J Radiol 2015; 80:526-528. [CrossRef]

(12.) Xing Y, Wang H, Yu X, Chen R, Hou Y. Assessment of coronary artery lesions in children with Kawasaki disease: evaluation of MSCT in comparison with 2-D echocardiography. Pediatr Radiol 2009; 39:1209-1215. [CrossRef]

(13.) Duan Y, Wang X, Cheng Z, Wu D, Wu L. Application of prospective ECG-triggered dual-source CT coronary angiography for infants and children with coronary artery aneurysms due to Kawasaki disease. Br J Radiol 2012; 85:1190-1197. [CrossRef]

(14.) Yu L, Fletcher JG, Shiung M, et al. Radiation dose reduction in pediatric body CT using iterative reconstruction and a novel image-based denoising method. AJR Am J Roentgenol 2015; 205:1026-1037. [CrossRef]

(15.) Ghoshhajra BB, Lee AM, Engel LC, et al. Radiation dose reduction in pediatric cardiac computed tomography: experience from a tertiary medical center. Pediatr Cardiol 2014; 35:171-179. [CrossRef]

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(17.) Dietz SM, Tacke CE, Kuipers A, et al. Cardiovascular imaging in children and adults following Kawasaki. Insights Imaging 2015; 6:697-705. [CrossRef]

Mecit Kantarci [iD]

Elif Guven [iD]

Naci Ceviz [iD]

Hayri Ogul [iD]

Recep Sade [iD]

From the Departments of Radiology (M.K. [??] akkanrad@hotmail.com, E.G., H.O., R.S.) and Pediatric Cardiology (N.C.), Ataturk University School of Medicine, Erzurum, Turkey.

You may cite this article as: Kantarci M, Guven E, Ceviz N, Ogul H, Sade R. Vascular imaging findings with high-pitch low-dose dual-source CT in atypical Kawasaki disease. Diagn Interv Radiol 2019; 25: 50-54.

Main points

* Kawasaki disease is a self-limited vasculitis of small- and medium-sized arteries.

* The disease mainly affects infants and children younger than 5 years of age.

* When clinical criteria are insufficient for the diagnosis of typical Kawasaki disease, atypical Kawasaki disease can be considered.

* High-pitch low-dose dual-source CT can detect all types of aneurysms, as well as stenosis and occlusion of vessels in patients with atypical Kawasaki disease.

Received 6 March 2018; revision requested 2 April 2018; last revision received 19 June 2018; accepted 27 June 2018.

DOI 10.5152/dir.2018.18092
Table. CT angiographic distribution of aneurysms in patients with
atypical Kawasaki disease

Patient  Coronary  Pulmonary  Axillary  Ulnar   Renal   Iliac
number   artery    artery     artery    artery  artery  artery

 1       +
 2       +                                              +
 3                                              +
 4       +
 5       +         +
 6       +                    +         +
 7                                                      +
 8
 9       +
10
11                            + (*)

Patient  Femoral  Popliteal
number   artery   artery

 1
 2       +
 3
 4
 5
 6
 7                +
 8
 9
10
11

(*) The right axillary artery had thromboses.
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Title Annotation:ORIGINAL ARTICLE
Author:Kantarci, Mecit; Guven, Elif; Ceviz, Naci; Ogul, Hayri; Sade, Recep
Publication:Diagnostic and Interventional Radiology
Article Type:Report
Date:Jan 1, 2019
Words:2274
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