Coronary cameral fistula

Ran Xie, RT1; Sheng Wang, MD1; Bin Han, MD1; Pengyun Cheng, MD2; Xinglong Liu, MD2

1 Department of Radiology, Wulanchabu Municipal Central Hospital, Inner Mongolia, P. R. China

2 Siemens Healthineers, China

A 40-year-old female patient, suffering from intermittent palpitations, came to the hospital for a check up. Her medical history was unremarkable except for a known arterial hypertension. A coronary CT Angiography (cCTA) was requested for further evaluation.

cCTA images showed a diffusely dilated right coronary artery (RCA) as well as the first diagonal branch (D1) connecting via tortuous distal segments with a single fistulous connection, draining into the left ventricle (LV) chamber. The fistula had a small caliber with a bulbous change at the entrance. The drainage site was situated below the posterior atrioventricular groove. There were no signs of a LV hypertrophy present.

cVRT images and thin MIP images show the torturous trajectory of the dilated RCA and D1, connecting distally. A single fistula with a bulbous change at the entrance is seen below the posterior atrioventricular groove, draining into the LV chamber.
Courtesy of Department of Radiology, Wulanchabu Municipal Central Hospital, Inner Mongolia, P. R. China
Fig. 1: cVRT images (Figs. 1a & 1b) and thin MIP images (Figs. 1c & 1d) show the tortuous trajectory of the dilated RCA and D1, which are connected distally. A single fistula (arrows) with a bulbous change at the entrance is seen below the posterior atrioventricular groove, draining into the LV chamber.
Coronary cameral fistula, defined as the entry of a coronary artery into any of the cardiac chambers, commonly originates from the RCA and seldomly involves the LV chamber. [1] In this rare case, the fistula originates from the distal connection of the RCA and the D1, and drains directly into the LV chamber. CT images used for assessment are acquired with prospective ECG triggered sequential scanning and reconstructed at the systolic phase. The system is designed to identify the best systolic phase and to reconstruct the images automatically. This has a significant impact on timesaving in the daily workflow. Another helpful technical feature is the adaptive collimation, in 2.4 mm steps according to the defined scan range. This reduces radiation outside the defined scan range, due to the fixed collimation settings. Despite the patient’s elevated and irregular heart rate (76 – 84 bpm), an optimal image quality is achieved, owing to the high temporal resolution of 66 ms granted by the dual source CT scanner, SOMATOM Force. Image post processing, using maximum intensity projection (MIP) and cinematic volume rendering technique (cVRT), facilitate the three-dimensional demonstration of the complex anatomy.

Scanner

Scan area

Heart

Scan mode

Prospective ECG triggered sequential scan

Scan length

131 mm

Scan direction

Cranio-caudal

Scan time

4.4 s

Tube voltage

100 kV

Effective mAs

334 mAs

Dose modulation

CARE Dose4D

CTDIvol

25.3 mGy

DLP

333.7 mGy*cm

Rotation time

0.25 s

Slice collimation

176 x 0.6 mm

Slice width

0.75 mm

Reconstruction increment

0.5 mm

Reconstruction kernel

Bv40

Heart rate

76 - 84 bpm

Contrast

320 mg/mL

Volume

60 mL + 30mL saline

Flow rate

5 mL/s

Start delay

Bolus tracking with 100 HU at ascending aorta + 5 s