Intimal Dissection

The sonographic image of intimal dissection in the aorta or in aneurysms is similar to that of an endovascular stent; however, most often the patient’s history is known, which then facilitates the differential diagnosis. Furthermore, the intima tends to be thicker and presents as

a solitary echogenic intraluminal band. The origin of the dissection can be identified in only a few cases. An undulating membrane is a typical sign. True and false lumina can be differentiated by contrast-enhanced ultrasound (CEUS): a true lumen presents an early

contrast flow, while a false one presents late. The most important preoperative questions can be answered by CEUS: Are the renal arteries running out of the false lumen and is the kidney perfused? Are the liver and kidneys perfused (Fig.1.51).

1

Aorta, Arteries

Perivascular Mass

Pseudoaneurysm

Arteriovenous Fistula/Arteriovenous Malformation

Suture-line Aneurysm

Suture-line Breakdown, Graft Infection

Hematoma, Abscess

Lymphomas, Metastases

Retroperitoneal Fibrosis

Horseshoe Kidney

Intestinal Loop

Perivascular masses may originate from the vessel itself (pseudoaneurysm, suture-line breakdown, graft infection) or arise completely independently of it. Ultrasound plays a vital

role in the differential diagnosis of these diseases. The diagnosis cannot be confirmed in all cases; quite often the clinical picture will yield important clues, and sometimes additional

imaging modalities are required or other diagnostic measures such as ultrasound-guided needle aspiration for cytology and histology.

Pseudoaneurysm

thrombosed, thus making open surgery a thing of the past. This does not apply to arteriovenous fistulas.14 The arterial influx can be occluded more rapidly with an ultrasoundguided injection of fibrin glue (Fig.1.52).

As is true for pseudoaneurysms, the most common cause of arteriovenous fistulas is iatrogenic (e. g., catheterization); shrapnel injuries have become quite rare. The sonographic diagnosis is derived from the B-mode image and

the arterial signal detected in the vein during duplex scanning.

An arteriovenous malformation is a congenital vascular anomaly in which an artery and vein are interconnected by undifferentiated

vessels without a capillary network. The tangled vessels can be made visible by color duplex and spectral analysis in the presence of a high shunt volume (Fig.1.53, Fig.1.54, see also Fig. 2.69, p. 95).

1

Aorta, Arteries

1

Vessels

Retroperitoneal Fibrosis

In rare cases a hyperechoic periaortic and pericaval “encasing” mass may be due to retroperitoneal fibrosis, a disease associated with other manifestations (Fig.1.58, also see Chapter 11 “Urinary Tract,” Fig.11.28, p. 391).

Fig. 1.58 Retroperitoneal fibrosis: hypoechoic masses (calipers) encasing the aorta (AO). WS = spine; VC = compressed vena cava.

A hypoechoic mass anterior to the aorta, round or oval (in the transverse diameter), will confirm the diagnosis of a horseshoe kidney, if the study is continued into the flanks and a connection with the kidney becomes evident (Fig.1.59).

Fig. 1.59 Hypoechoic mass resembling lymph nodes anterior to the large abdominal vessels: horseshoe kidney

(N). AO = aorta; VC = vena cava.

Intestinal Loop

Differential diagnosis of a para-aortic mass has to include the possibility of a hypoechoic intestinal loop distended by fluid. If the mass is observed over a period of time and shows signs of peristalsis, this will settle any doubts (Fig.1.60).

Fig. 1.60 Periaortic “mass”: fluid-filled intestinal loop, differentiation from a true intra-abdominal mass is possible only by its motion. AO = aorta; D = small bowel.