CT Angiography of the portal venous system:
Techniques and interpretation.

E. Squillaci MD, M. Pocek MD,S. Fosi MD, P. Gamba MD, M.G. Ciolfi MD, F. Maspes MD, M.L.Grandinetti MD, G. Simonetti MD

INTRODUCTION

Spiral CT angiography (CTA) is the latest in a series of technical innovations in vascular imaging which allows for spectacular three-dimensional reconstructions of the blood vessels and organs. Most of the work evaluating the utilityof CTA has been performed in the abdomen, mainly in the aorta and splancnicvessels. With this exibit we demonstrate the technique and the possibilitiesof CTA in the portal venous system.

TECHNIQUE

CM  Injection
-Power injector
-16 -18 G needle antecubital vein
-Non ionic e.v. cm
-Oral cm: water

                                Portal thrombosis    Portal hypertention

Amount	3 ml/s 150ml	2 ml/s  180ml
Delay	60 s	80s
Concentration	370 mgI/ml	300 mgI/ml

 

Acquisition parameters (Philips TOMOSCAN SR 7000)
 

-Kvp=120  -mA=250-300  -Matrix=512 X 512  -Interpolation=180°  -Rec Index=2mm

-Slice thickness=3-5mm  -Table Feed=5mm/s  -Acquisition time=30s  -Coverage=15cm  -Pitch=1-1.6

 

Reconstruction Techniques
Workstation: Easy Vision CT/MR R2
2D (MPR, CPR)  3D(MIP, SSD)

   
                 A                                              B                                                 C

NORMAL ANATOMY OF THE PORTAL VENOUS SYSTEM
  A: CPR, B: MIP, C-D: SSD, after subtraction of the liverparenchyma.  

CTA FINDINGS

Spleno-portal axis

- Stenosis
- Partial  thrombosis
- Complete  thrombosis

                         A                                                B                        

PORTAL VEIN THROMBOSIS
A: CPR reconstruction of partial thrombosis at the confluence between splenic and portal vein.
Residual flow is well demonstrated.
B: MIP recontruction of partial thrombosis of the main portal vein.
 

Collaterals

- Gastro-esophageal
- Spleno-renal
- Porto-hepatic
- Paraumbilical

   

                      A                                           B                                  C                        

COLLATERALS
A: Spleno-renal shunt (MPR).
B-C: Patency of the paraumbilical vein (SSD).

TIPS follow-up

- Patency

 

                      A                                               B                                              C

FOLLOW-UP AFTER  TIPS
A: CPR allow to follow the stent and to evaluate the relationshipbetween hepatic and portal vein. Flow inside the stent is well demonstrated.
B:  SSD demonstrate only stentposition.
C: Stent thrombosis. MPR (top) demonstrate the absence of flow andthethrombus, MIP (bottom) the presence of gastric curve collaterals.

Pre-operatory evaluation

SMALL HEPATIC TUMOR IN A  CIRRHOTIC  LIVER
SSD images demonstrate the relationship of the tumor with the portal system
 

LIMITATIONS

MPR - No significant limitations
CPR - Overlapping of non opacified structures
MIP - Slow venous flow
SSD - Thrombosis

Comparison 2D/3D  technique

                                 MPR - CPR                MIP                    SSD

THROMBOSIS	2	1	0
COLLATERALS	0	2	1
TIPS	2	1	0

 
0 = POOR
1 = GOOD
2 = EXCELLENT

CTA versus MRA

CTA
- Not sensible to turbolent flow
- Visualization of vessels and parenchyma
MRA
- No iodinated cm
- Directional informations

CTA versus color US

CTA
- Large, obese Patients
- Ascites
- Large collaterals

Color US
- Easy and fast
- Quantitative and directional analysis

CONCLUSIONS
Good imaging quality was obtained in all Patients.
Technique of choice for evaluation of PV thrombosis.
Good evaluation of collaterals.
Clinical indications when doppler-US is not conductive, and in casesof very slow flow.