ABSTRACT
Transcatheter embolization is a well-established treatment for renal arteriovenous fistula (AVF) in selected cases. Transarterial approach has been the conventional route of access of the AVF. In large arteriovenous shunts, however, transarterial approach inherits the risk of distal migration of embolization material with subsequent pulmonary embolism. We report a case of giant high-flow renal arteriovenous fistula treated with coil embolization. Arterial approach was attempted with double catheter technique, however complicated with coil mass dislodgement. We have retrieved the coil mass via transvenous route with simultaneous pulmonary circulatory protection and subsequent successful transvenous coil embolization with complete obliteration of the AVF was performed.
ABSTRACT
PURPOSE: The objective of this study is to assess artifact reduction and image quality using dual-energy computed tomography (DECT) and metal artifact reduction techniques in patients with metallic implants. METHODS: Forty patients with metallic implants, who had targeted CT performed by DECT during March to September 2018, were prospectively recruited. Post-processing with monoenergetic extrapolation at 70 and 150 keV was performed. Forty matched controls with metallic implants with single-energy CT (SECT) performed were selected. Attenuation value, noise, and signal-to-noise ratio (SNR) at the site of maximal artifact were measured at muscle and fat areas. Image quality of three sets of images (70 keV, 150 keV, and SECT) was assessed by two independent reviewers using a 5-point Likert-type scale. Statistical analysis of measured values, Likert-type scales, and radiation doses (volume CT dose index (CTDIvol)) of DECT and SECT were performed with Mann-Whitney U test. RESULTS: As compared to SECT, high keV reconstruction of DECT show (1) significantly higher values within muscle and fat surrounding the implant (DECT vs. SECT-muscle: -96 Hounsfield units (HU) vs. -405 HU, fat: -115 HU vs. -301 HU; p < 0.001), (2) significantly lower mean image noise (75 HU vs. 129 HU; p = 0.02), and (3) higher SNR (-0.8 vs. -4.3; p < 0.001). In addition, image quality of high keV reconstruction was rated superior to the other two groups on Likert-type scales ( p < 0.001). The mean radiation doses (CTDIvol) were comparable between DECT and SECT (14.2 mGy vs. 19.3 mGy; p = 0.08). CONCLUSION: For patients with metallic implants, monoenergetic extrapolation of DECT at high keV can reduce metal artifacts, increase SNR, and improve qualitative image quality at comparable radiation dose.
