Contrast-Enhanced Magnetic Resonance Angiography for Diagnosis of Portosystemic Shunts in 10 Dogs

Abstract

Computed tomography angiography, sonography, scintigraphy, and portography can be used to evaluate the portal vasculature to evaluate for a portosystemic shunt (PSS). Time-of-flight magnetic resonance angiography (TOF-MRA) and contrast-enhanced MRA (CE-MRA) are other potentially useful techniques. The aim of this study was to evaluate CE-MRA in 10 dogs suspected of having a PSS. Noncontrast MR images of the abdomen were obtained using a Siemens Symphony MR-scanner (1.5 T) and a T1-weighted FLASH-3D sequence with a very short scan time (about 20 s). After injection of contrast medium, the initial sequence was repeated five times. The sequence with the best contrast medium filling of the portal vasculature was selected subjectively, subtracted from the initial survey image series, and a maximum intensity projection (MIP) of the subtraction data, in multiple views, was created. The cross-sectional and MIP images were evaluated for abnormal portosystemic vasculature. A single PSS was identified and confirmed at surgery in all dogs. A portocaval shunt was found in five dogs, a portophrenic shunt in three dogs, a portoazygos shunt in one, and a central divisional intrahepatic shunt in one other dog. Based on our results, CE-MRA is a useful tool for imaging abdominal and portal vasculature and for the diagnosis of a PSS. r

Computed tomographic and magnetic resonance imaging features of canine segmental caudal vena cava aplasia

“…The detailed differentiation of the different vascular systems is particularly valuable if complex anomalies are present, such as those described here, to avoid unnecessary surgical interventions or to guide the preoperative planning of surgical or radiological interventional portosystemic shunt ligation or occlusion procedures. Abdominal MRA studies have also gained popularity in the diagnosis of canine abdominal vascular disorders, and particularly, the use paramagnetic contrast media has increased lesion conspicuity (Seguin and others 1999, Holmes and others 2006, Bruehschwein and others 2009, Sharpley and others 2008, Cavrenne and Mai 2009, Mai 2009).…”

Knee subchondral bone perfusion and its relationship to marrow fat and trabeculation on multi-parametric MRI and micro-CT in experimental CKD

“…After image acquisition, we measured the signal intensity and vessel diameters of the popliteal artery. The phase of best vascular enhancement was decided subjectively and the image mask was subtracted from the unenhanced series 29, 30 . Images were evaluated using maximum intensity projections (MIP) to assess the bilateral popliteal signal intensity and vessel diameter changes.…”

“…CE-MRA can provide excellent and high resolution morphological coverage of the peripheral vascular anatomy in a short acquisition time 29, 30 . Multi-parametric MRI enables investigation of the changes in subchondral bone marrow parameters, including fat-water content and blood perfusion.…”

Unusual haemodynamics in two dogs and two cats with portosystemic shunt - implications for distinguishing between congenital and acquired conditions

“…Abnormal venous porto-caval connections are widely described in small animal veterinary literature, with majority of cases reported in dogs (Lamb, 1996;Bertolini et al, 2006;Bertolini, 2010aBertolini, , 2010bBruehschwein et al, 2010;Nelson and Nelson, 2011;Fukushima et al, 2014). These vascular anomalies are divided in two main categories according to their origin: congenital PSS (CPSS) deriving from embryogenetic errors in the development of vitelline and cardinal venous systems (Ferrell et al, 2003), and acquired PSS (APSS) deriving from recanalization of pre-existing, vestigial embryonic vascular connections between portal and caval systems as a consequence of portal hypertension (PH) (Fossum, 2002;Szatmari et al, 2004;Bertolini, 2010a).…”