Vascular imaging findings with high-pitch low-dose dual-source CT in atypical Kawasaki disease. (2024)

Kawasaki disease (KD) is an acute, febrile, self-limited vasculitisthat affects small- and medium-sized arteries, with a predilection forthe coronary arteries (1). The disease mainly affects infants andchildren younger than 5 years of age. The etiology of KD is unknown, andthere are no specific diagnostic tests (2). The diagnosis of thisdisease is ideally made by clinical criteria according to the AmericanHeart Association. Typical or classical Kawasaki (TKD) disease can bediagnosed if a fever lasts longer than 5 days and if a patient has 4 ofthe 5 clinical features. However, according to the Japanese guidelines,atypical or incomplete Kawasaki disease (AKD) is defined as the presenceof 4 or fewer of the main findings of KD regardless of the presence orabsence of coronary artery aneurysm (CAA).

In some cases with unexplained prolonged fever, the clinicalfeatures 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 andother vascular complications can be more frequently seen because thediagnosis can be delayed. Therefore, early diagnosis and treatment isvery important to prevent complications (5).

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

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

Methods

Patient selection

The study subjects seen at our institution between 2012 and 2017with suspected AKD who did not have enough clinical features for adiagnosis of TKD according to the American Heart Association diagnosticguidelines were included in our study. We evaluated 17 consecutivepatients who were referred to us by our center or an outside center atthe pediatric cardiology clinic. High-pitch low-dose CT angiography wasperformed in all patients because systemic aneurysms can be presentwithout CAA. Each CT angiography study was examined for aneurysms andocclusive disease. The age of the patients ranged from 2 months to 11.3years, with a mean age of 3 years. Seven of the patients were male. Sixpatients did not have any aneurysms and were therefore excluded. Thisstudy was approved by our institutional ethics committee (the decisionnumber of ethics committee approval: B.30.2.ATA.0.01.00/91), andinformed consent was obtained from the families of all patients.

CT protocol

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

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

We evaluated a broad range of anatomic areas on the CT. Theexamination was usually focused on clinical symptoms of the patients aswell as the coronary arteries such as the branches of the abdominalaorta and extremity arteries. Generally positive findings were detectedat symptomatic areas and in the different arteries. Each of the scanswas finished in 1-1.5s without any complications.

All of the images were assessed in consensus by two radiologistswho were blinded to the information about the patients and who had morethan 4 years of experience at a workstation (Syngo Via, SiemensHealthcare).

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; 7males), and AKD was diagnosed in these patients (Table). CAA was presentin 4 patients without SAA (36%) (Fig. 1). SAA was present in 4 patientswithout CAA (36%). Three patients had both SAA and CAA (27%).

Two patients had sterile pyuria, proteinuria and flank pain. CTangiography demonstrated the presence of renal artery aneurysms withoutCAA (18%) (Fig. 2). Pulmonary artery aneurysm was present in addition toCAA in one patient (9%) (Fig. 3).

Axillary artery aneurysms were found in two patients (18%). In onepatient with axillary artery aneurysm, CAA was also present. In theother patient, the axillary artery aneurysm was the only arterialaneurysm that was identified on CT (Fig. 4). This axillary artery wasthrombosed, and peripheral gangrenous features were found in thispatient.

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

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

Right iliac artery aneurysm, the largest of these aneurysms, wasmeasured 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 mGydepending on the patient's body weight.

Discussion

The diagnosis of TKD is easy, and treatment can be started withoutloss of time, while AKD has an atypical clinical presentation, and itsdiagnosis is very difficult. When treatment is delayed, the consequencesmay be disastrous. Thus, in patients with AKD, determining the presenceof vascular aneurysms is crucial (4, 6). Coronary arteries are the mostcommon location for aneurysms in patients with KD, but SAAs can also beseen on rare occurrences.

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

High-pitch low-dose CT angiography is an impressive alternativeimaging modality for patients with AKD. CT angiography isfree-breathing, does not require anesthesia and does not depend on theuser (8, 11). This technique can detect aneurysms that are missed byechocardiography (22) and can also detect more distal aneurysms that areidentified with ultrasonography (13) along with SAA in any location inyoung children. Further, it is a noninvasive technique, and CTangiography can detect vascular aneurysms, occlusions and stenosespreviously identified by invasive angiography. In addition, with thismodality, the wall of the vessel can be assessed in addition to itslumen. Traditional CT angiography, unlike low dose CT angiography, ismore harmful especially for young children. During routine pediatricbody CT examinations, the radiation burden is 4.4-8.5 mSv (14). In ourstudy, we used the SAFIR denoising method on work stations that maintainspatial resolution and retain diagnostic quality images. With thistechnique, the effective radiation dose can be decreased (1.4-4.3 mSv,main 1.9 mSv), and high-resolution images can be obtained easily andquickly (15).

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

Our study has several limitations. First, the sample size was smalldue to the relatively rare incidence of the disease. Second, we were notable to compare our results with other modalities because we wanted touncover the efficiency of CT angiography. Although the radiation dose isreduced by high pitch, this imaging technique still requires radiation.

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

Conflict of interest disclosure

The authors declared no conflicts of interest.

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Mecit Kantarci [iD]

Elif Guven [iD]

Naci Ceviz [iD]

Hayri Ogul [iD]

Recep Sade [iD]

From the Departments of Radiology (M.K. [??] [emailprotected],E.G., H.O., R.S.) and Pediatric Cardiology (N.C.), Ataturk UniversitySchool 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-sourceCT in atypical Kawasaki disease. Diagn Interv Radiol 2019; 25: 50-54.

Main points

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

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

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

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

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

DOI 10.5152/dir.2018.18092

Table. CT angiographic distribution of aneurysms in patients withatypical Kawasaki diseasePatient Coronary Pulmonary Axillary Ulnar Renal Iliacnumber artery artery artery artery artery artery 1 + 2 + + 3 + 4 + 5 + + 6 + + + 7 + 8 9 +1011 + (*)Patient Femoral Poplitealnumber artery artery 1 2 + 3 4 5 6 7 + 8 91011(*) The right axillary artery had thromboses.